CN101025512A - Display device - Google Patents

Abstract

The present invention provides a display device that can be improved at least in a specific direction without changing the design of the basic structure of the display device, without being limited by a white display state or a black display state, and without impairing display quality in other directions. Viewing angle dependence of contrast ratio. The above-mentioned display device comprises a display device whose contrast ratio has viewing angle dependence, and an anisotropic scattering film having an anisotropic scattering layer, wherein the above-mentioned anisotropic scattering film is inclined at a certain angle from a normal direction of an observation surface of the display device. The contrast ratio in the rear direction substantially coincides with the direction in which the contrast ratio takes an extreme value, has a scattering center axis, and is arranged on the viewing surface side of the display device.

Description

display device

technical field

The invention relates to a display device. More specifically, it relates to a display device including a display device such as a liquid crystal display device and an anisotropic scattering film.

Background technique

A liquid crystal display device represented by a twisted nematic (Twisted nematic: TN) mode is known as a typical example of a display device whose display performance has viewing angle dependence (viewing angle characteristic). The so-called "display performance has viewing angle dependence" refers to the situation observed from the front direction (the normal direction of the viewing surface of the display device, the direction where the viewing angle is 0 degrees) and the situation observed from an oblique direction (the direction where the viewing angle is greater than 0 degrees) Under different conditions, the contrast ratio (contrast ratio), grayscale characteristics, chromaticity and other display performances are different. In general, it is known that these display performances are not as good when viewed from an oblique direction as when viewed from a frontal direction.

In a TN mode liquid crystal display device, the contrast ratio gradually decreases as the viewing angle increases in the up, down, left, and right directions (3 o'clock/6 o'clock/9 o'clock/12 o'clock directions of the clock). For example, even if the contrast ratio is 320 when viewed from the front, when viewed from an angle of view of 75 degrees in the upward direction (direction at 12 o'clock), when viewed from an angle of view of 50 degrees in the downward direction (direction at 6 o'clock) Below, the contrast ratio becomes 10 when viewed from a viewing angle of 65 degrees in the left direction (direction at 9 o'clock) and viewed from a viewing angle of 68 degrees in the right direction (direction at 3 o'clock). In addition, although the display color is neutral (no coloration occurs) when viewed from the front, it appears yellowish when viewed from the up, down, left, and right directions. Especially when viewed from below, an abnormal phenomenon of gradation characteristics called gradation inversion, in which the positive and negative of the displayed image are reversed, is also observed. The viewing angle dependence of the display performance in such a liquid crystal display device is derived from the refractive index anisotropy of the liquid crystal molecules, the polarized light absorption characteristics and polarized light transmission characteristics of the polarizing plate, and the optical anisotropy of the constituent parts. The opposite sex can be said to be the characteristic inherent in the liquid crystal display device.

As a method of improving the viewing angle dependence of the display performance of a liquid crystal display device, various methods have been proposed so far. As such a method, for example, a pixel division method (half-tone gray scale method in which one pixel is divided into a plurality and the voltage applied to each pixel is changed by a certain ratio; or a pixel is divided into multiple domains, control the alignment of liquid crystal for each domain (domain division method, etc.), in-plane switching (In-Plane Switching: IPS) mode that applies a lateral electric field to the liquid crystal, drive vertical alignment when no voltage is applied Display modes such as Multi-domain Vertical Alignment (MVA) mode of liquid crystal, OCB (Optically Compensated Birefringence: Optically Compensated Birefringence) mode in which a bend alignment unit is combined with a retardation film, and the use of phase The optical compensation method of the poor film, etc., have also been studied and used in appropriate combinations, and these methods are often used in commercialized liquid crystal display devices.

However, in the case of using the pixel division method or the above-mentioned display mode, it is necessary to change the structure of the alignment film, the electrode, etc., so it is necessary to establish a manufacturing technology or reinstall the manufacturing equipment, resulting in difficulty in manufacturing and high cost. Improvements have been made in this regard. room for. In addition, the improvement effect of viewing angle dependence is not sufficient. Furthermore, the improvement effect of the optical compensation method using a retardation film is also limited. For example, since the phase difference value most suitable for phase difference compensation of a liquid crystal cell (cell) differs between black display and white display, phase difference compensation of liquid crystal cells cannot be performed for both black display and white display. In addition, on the axis orientation of the polarization axis (transmission axis and absorption axis) of the polarizer, in principle, all the compensation effects based on the retardation film cannot be obtained, and the improvement effect is limited to a specific orientation. In the range of azimuth angle, there is also room for improvement in this regard.

As a method of improving the viewing angle dependence of display performance of a liquid crystal display device other than the above, a method of providing a scattering film on the viewing surface side of a liquid crystal display device to average out emitted light is known. This method is applicable to all display modes and basically does not require structural changes of the display unit. In addition, unlike the above-mentioned optical compensation method using a retardation film, the effect is obtained in both black display and white display, and the effect is also effective in the axial direction of the polarization axis of the polarizing plate.

In addition, as a light source of a general liquid crystal display device, a diffuse backlight system that emits diffuse light is used. The liquid crystal display mode or polarizer basically has the best characteristics for vertically incident light, so the light from the diffuse backlight system is parallelized as much as possible by the lens film, etc., and is vertically incident on the liquid crystal display device (liquid crystal unit) . As a result, an improvement effect of the viewing angle dependence can be further obtained, and techniques related to this are often proposed.

However, since a simple and efficient method for obtaining parallel light has not yet been established, an improved method based on the viewing angle dependence of the scattering film is used in combination with a diffuse backlight system as described above. At this time, as described above, although the improvement effect of the viewing angle dependence can be obtained, in the black display state, the travel path of a part of the leaked light incident obliquely incident on the liquid crystal cell is bent in the front direction by the scattering film, so the light in the front direction The increased light leakage makes the contrast ratio in the frontal direction much lower, and there is room for improvement in this regard. This is because the scattering performance of the scattering film is isotropic, so even if the incident angle is slightly changed, the scattering characteristics of the scattering film for transmitted light do not vary greatly.

In contrast, for a resin composition composed of a plurality of compounds having one or more photopolymerizable carbon-carbon double bonds in molecules with different refractive indices, it is disclosed that the A light control sheet manufactured by irradiating ultraviolet light with a light source to cure the resin composition (for example, refer to JP-A-63-309902, JP-A-64-40903, JP-A-64-40905, JP-A JP-A-64-40906, JP-A-64-77001, JP-1-147405, JP-1-147406, JP-2-51101, JP-2-54201, JP-2 -67501 communique, Japanese patent publication No. 3-87701, Japanese patent publication No. 3-109501, Japanese patent publication No. 6-9714), and a liquid crystal display device equipped with such a light control sheet (for example, refer to Japanese patent publication No. 7-64069 Publication No. 2000-180833 and JP-A-2000-180833.). Such light management sheets selectively scatter light incident from specific angles. Therefore, if this light control sheet is used, it is thought that the fall of the contrast ratio of the front direction mentioned above can be eliminated to some extent.

However, as shown in FIG. 50 , in the cured resin of the light control sheet, it is considered that the longitudinal direction of the linear light source 51 disposed above the light control sheet 50 is consistent with that of the light control sheet 50, and the refractive index and the outer periphery are formed parallel to each other. Plate-like regions 40 of different regions. Therefore, the incident angle dependence of the scattering characteristic shown by the light control sheet 50 is basically invisible when the plate-shaped region 40 in FIG. It can be seen when there is no change in the refractive index and it is rotated around the uniform B-B axis.

FIG. 51 is a schematic diagram showing the incidence angle dependence of the scattering characteristics shown by the light control sheet 50 in FIG. 50 . The vertical axis represents the straight-line transmitted light amount, which is an index showing the degree of scattering, and the horizontal axis represents the incident angle. In addition, the solid line and the dotted line in FIG. 51 respectively represent the case where the light control sheet 50 is rotated around the A-A axis and the B-B axis in FIG. 50 . In addition, the positive and negative of the incident angle means that the direction in which the light control sheet 50 is rotated is opposite.

The solid line in FIG. 51 has a small amount of straight-line transmitted light regardless of the front direction or the oblique direction, which means that in the case of rotation around the A-A axis, the light control sheet 50 is in a scattering state regardless of the incident angle. In addition, the dotted line in FIG. 51 has a small amount of linearly transmitted light in the direction near 0 degrees, which means that the light control sheet 50 scatters light in the front direction when rotating around the B-B axis. In the direction where the incident angle is large, the amount of transmitted light increases in a straight line, which means that the light control sheet 50 transmits light in an oblique direction when it is rotated around the B-B axis.

In this way, in the conventional light control sheet, the anisotropic scattering characteristic (the characteristic that the scattering characteristic changes when the incident angle is changed) can only be obtained in a specific orientation, so the viewing angle-dependent improvement effect can only be obtained in a specific orientation, Light incident from an oblique direction in other directions is scattered substantially uniformly regardless of the incident angle, and thus degrades display quality in other directions, and there is room for improvement in this respect.

Contents of the invention

The present invention is made in view of the above-mentioned current situation, and its purpose is to provide a display device, which can not change the design of the basic structure of the display device, is not limited by the white display state or black display state, and does not impair the display quality in other directions. way to improve the viewing angle dependence of the contrast ratio at least in certain orientations.

The inventors of the present invention have conducted various studies on a display device having a display device having a viewing angle dependence of a contrast ratio and an anisotropic scattering film having an anisotropic scattering layer. First, focusing on the display device Viewing angle dependence of contrast ratio. In addition, focusing on display devices, there are usually azimuths in which the contrast ratio tends to decrease as the polar angle increases (the azimuth with a narrow viewing angle) and azimuths in which the contrast ratio remains high (the azimuth with a wide viewing angle). )Case. For example, in a typical VA-mode liquid crystal display device, in the up direction (the direction with an azimuth angle of 90 degrees), the down direction (the direction with an azimuth angle of 270 degrees), the left direction (the direction with an azimuth angle of 180 degrees) and In the right direction (direction with an azimuth angle of 0 degrees), the contrast ratio remains high even if the polar angle is increased. However, in the upper right direction (direction with an azimuth angle of 45 degrees) direction), the lower left direction (direction with an azimuth angle of 225 degrees), and the lower right direction (direction with an azimuth angle of 315 degrees), the contrast ratio tends to decrease as the polar angle increases compared to the up, down, left, and right directions.

Next, the present inventors paid attention to the scattering characteristics of an anisotropic scattering film having a scattering central axis. The anisotropic scattering characteristics (characteristics in which the scattering characteristics change when the incident angle is changed) of the above-mentioned anisotropic scattering film having a scattering central axis are substantially symmetric about the scattering central axis. Therefore, it is found that by arranging the anisotropic scattering film on the side of the viewing surface of the display device, and making the axis orientation of the scattering central axis and the direction inclined at a certain angle from the normal direction of the viewing surface of the display device, the contrast ratio is taken as The orientation of the extremum (the orientation of the above-mentioned wide or narrow viewing angle. Hereinafter, it is also referred to as "extreme orientation") is approximately the same, so that the light incident along the axial direction of the scattering central axis is approximately parallel (white brightness or black brightness) Scattering (diffusion) is performed in all directions centered on the scattering central axis and averaged, so that the viewing angle dependence of the contrast ratio can be improved at least in the extreme direction substantially coincident with the axial direction of the scattering central axis. For example, in the case where an anisotropic scattering film having a scattering center axis along the normal direction of the viewing surface of the display device is arranged on the viewing surface side of the display device, in the wide orientation centered on the direction of the polar angle 0 degrees On the other hand, the effect of improving the viewing angle dependence of the contrast ratio can be obtained. In addition, an anisotropic scattering film with a scattering central axis in a direction inclined 30 degrees from the normal direction of the viewing surface of the display device is arranged on the viewing surface side of the display device, and the axis orientation of the scattering central axis is consistent with the display When the extreme orientations of the devices are substantially the same, in the extreme orientations, the effect of improving the viewing angle dependence of the contrast ratio can be obtained in a range with a large polar angle centered on a direction with a polar angle of 30 degrees.

It was also found that this anisotropic scattering film exhibits anisotropic scattering characteristics even in directions other than the axial direction of the scattering central axis, unlike conventional anisotropic scattering films that show anisotropic scattering characteristics only in specific directions. Anisotropic scattering characteristics, so light incident from a direction other than the direction approximately parallel to the axis of the scattering central axis is only weakly scattered, and therefore, it is possible to suppress the direction where the contrast ratio is large due to scattering of light incident from this direction. display quality is degraded.

Also, in general display devices, various display properties such as γ curve and chromaticity are optimally designed in the direction where the contrast ratio is the largest, and the viewing angle dependence of these display properties shows the same tendency as the viewing angle dependence of the contrast ratio. Therefore, it was found that the viewing angle dependence of various display performances such as the γ curve and chromaticity can be improved at least in the extreme orientation substantially coincident with the axial orientation of the scattering central axis. In addition, it was found that the effect of improving the viewing angle dependence of the display performance by the above-mentioned anisotropic scattering film can be obtained regardless of the white display state or the black display state, unlike the retardation film. According to this mechanism, it has a positive effect on the display performance. For any display device dependent on the viewing angle, this improvement effect can be realized without performing a design change in the basic structure of the display device. Therefore, the present inventors have thought that the above-mentioned problems can be completely solved, and have achieved the present invention.

That is, the present invention is a display device comprising: a display device having a viewing angle dependence of contrast ratio; The normal direction of the observation surface is tilted at a certain angle in the direction where the contrast ratio takes the extremum value approximately the same orientation, has a scattering central axis, and is arranged on the observation surface side of the display device.

Description of drawings

FIG. 1A is a schematic diagram illustrating the direction of a polar angle Θ of a display device.

FIG. 1B is a schematic diagram illustrating an orientation of a display device.

FIG. 1C is a schematic diagram illustrating the azimuthal dependence of the contrast ratio of a display device in the direction of polar angle Θ (constant).

2A is a schematic perspective view showing an example of the structure of an anisotropic scattering film (anisotropic scattering layer) constituting the display device of the present invention.

Fig. 2B is a diagram illustrating the polar angle and axial orientation of the scattering center axis of the anisotropic scattering film.

2C is a schematic perspective view showing an example of the structure of an anisotropic scattering film (anisotropic scattering layer) constituting the display device of the present invention.

Fig. 3 is a graph showing the azimuth angle dependence of the contrast ratio of a VA mode liquid crystal display device in directions with polar angles of 10 degrees, 20 degrees and 45 degrees.

4 is an explanatory diagram showing the relationship between the axial orientation of the scattering central axis of the anisotropic scattering film constituting the display device of the present invention and the extreme value orientation of the display device.

5 is a graph showing an example of the incident angle dependence of the scattering characteristics of the anisotropic scattering film constituting the display device of the present invention. The solid line and the dotted line in the figure show the incidence angle dependence of the scattering characteristics when rotating about two mutually orthogonal rotation axes (short-side axis and long-side axis).

Fig. 6 is a schematic perspective view showing a method of measuring the scattering characteristics of a scattering film.

Fig. 7 is a graph showing the incidence angle dependence of the scattering characteristics of the first anisotropic scattering film.

8 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 1 of the present invention.

9 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device according to Embodiment 2 of the present invention.

10 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 3 of the present invention.

11 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device according to Embodiment 4 of the present invention.

12 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device according to Embodiment 5 of the present invention.

13 is a schematic perspective view showing the configuration of a TN-mode liquid crystal display device according to Embodiment 6 of the present invention.

14 is a schematic perspective view showing the structure of an IPS mode liquid crystal display device according to Embodiment 7 of the present invention.

Fig. 15 is a graph showing the incidence angle dependence of the scattering characteristics of an isotropic scattering film.

16 is a graph showing the azimuth-angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 degrees of the VA-mode liquid crystal display device manufactured in Example 1 of the present invention.

17 is a graph showing the azimuth-angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 degrees of the TN-mode liquid crystal display device produced in Example 6 of the present invention.

18 is a graph showing the azimuth-angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 degrees of the IPS mode liquid crystal display device manufactured in Example 7 of the present invention.

19 is a graph showing the azimuth-angle dependence of the contrast ratio in the direction of the polar angle Θ = 45 degrees of the OCB mode liquid crystal display device manufactured in Example 8 of the present invention.

20A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 1 of the present invention at azimuth angles Φ=90 and 270 degrees.

20B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 1 of the present invention at the azimuth angle Φ=0, 180°2 directions.

21A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 2 of the present invention at azimuth angles Φ=90 and 270 degrees.

21B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 2 of the present invention at the azimuth angle Φ=0, 180°2 directions.

22A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 3 of the present invention at azimuth angles Φ=90 and 270 degrees.

22B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 3 of the present invention at the azimuth angle Φ=0, 180 degrees 2 directions.

23A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 4 of the present invention at the azimuth angle Φ=90 and 270 degrees.

23B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 4 of the present invention at the azimuth angle Φ=0, 180 degrees 2 directions.

24A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 5 of the present invention at azimuth angles Φ=90 and 270 degrees.

24B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 5 of the present invention at the azimuth angle Φ=0, 180 degrees 2 directions.

25A is a graph showing the polar angle dependence of the contrast ratio of the TN mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) of Example 6 of the present invention at the azimuth angle Φ=45, 225°2 directions.

25B is a graph showing the polar angle dependence of the contrast ratio of the TN mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) of Example 6 of the present invention at the azimuth angle Φ=135, 315 degrees 2 directions.

26A is a graph showing the polar angle dependence of the contrast ratio of the IPS mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 7 of the present invention at the azimuth angle Φ=90, 270°2 directions.

26B is a graph showing the polar angle dependence of the contrast ratio of the IPS mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 7 of the present invention at the azimuth angle Φ=0, 180°2 directions.

27A is a graph showing the polar angle dependence of the contrast ratio of the OCB mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) of Example 8 of the present invention at the azimuth angle Φ=45, 225 degrees 2 directions.

27B is a graph showing the polar angle dependence of the contrast ratio of the OCB mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Example 8 of the present invention at azimuth angles Φ=135 and 315°2.

28A is a graph showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 1 at azimuth angles Φ=90 and 270 degrees.

28B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 1 at the azimuth angle Φ=0 and 180 degrees.

29A is a graph showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 2 at azimuth angles Φ=90 and 270 degrees.

29B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 2 at the azimuth angle Φ=0, 180 degrees.

30 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 9 of the present invention.

31 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 10 of the present invention.

32 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 11 of the present invention.

33 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device according to Embodiment 12 of the present invention.

34 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 13 of the present invention.

35 is a schematic perspective view showing the configuration of a TN-mode liquid crystal display device according to Embodiment 14 of the present invention.

36 is a schematic perspective view showing the configuration of a TN-mode liquid crystal display device according to Embodiment 15 of the present invention.

37 is a schematic perspective view showing the configuration of an IPS mode liquid crystal display device according to Embodiment 16 of the present invention.

38A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 9 of the present invention at the azimuth angle Φ=45, 225 degrees 2 directions.

38B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 9 of the present invention at azimuth angles Φ=135 and 315°2.

39A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 10 of the present invention at the azimuth angle Φ=45, 225°2.

39B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 10 of the present invention at azimuth angles Φ=135 and 315°2.

40A is a diagram showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) in Example 11 of the present invention at the azimuth angle Φ=45, 225 degrees 2 directions.

40B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 11 of the present invention at azimuth angles Φ=135 and 315 degrees.

41A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 12 of the present invention at the azimuth angle Φ=45, 225 degrees 2 directions.

41B is a graph showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 12 of the present invention at azimuth angles Φ=135 and 315 degrees.

42A is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 13 of the present invention at the azimuth angle Φ=45, 225 degrees 2 directions.

42B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) in Example 13 of the present invention at azimuth angles Φ=135, 315°2.

43A is a diagram showing the polar angle dependence of the contrast ratio of the TN mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) in Example 14 of the present invention at the azimuth angle Φ=90, 270°2 directions.

43B is a diagram showing the polar angle dependence of the contrast ratio of the TN mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) in Example 14 of the present invention at the azimuth angle Φ=0, 180°2 directions.

44A is a graph showing the polar angle dependence of the contrast ratio of the TN mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) of Example 15 of the present invention at azimuth angles Φ=90 and 270 degrees.

44B is a graph showing the polar angle dependence of the contrast ratio of the TN mode liquid crystal display device (dotted line) and the liquid crystal display device (solid line) of Example 15 of the present invention at the azimuth angle Φ=0, 180 degrees 2 directions.

45A is a diagram showing the polar angle dependence of the contrast ratio of the IPS mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Example 16 of the present invention at the azimuth angle Φ=45, 225 degrees 2 directions.

45B is a diagram showing the polar angle dependence of the contrast ratio of the IPS mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Example 16 of the present invention at azimuth angles Φ=135 and 315°2.

46A is a diagram showing the polar angle dependence of the contrast ratio of the OCB mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Example 17 of the present invention at the azimuth angle Φ=90, 270°2 directions.

46B is a diagram showing the polar angle dependence of the contrast ratio of the OCB mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Example 17 of the present invention at the azimuth angle Φ=0, 180°2 directions.

47A is a graph showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 1 at azimuth angles Φ=45 and 225 degrees.

47B is a graph showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 1 at azimuth angles Φ=135 and 315 degrees.

48A is a graph showing the polar angle dependence of the contrast ratio of the VA mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 3 at azimuth angles Φ=45 and 225 degrees.

48B is a graph showing the polar angle dependence of the contrast ratio of the VA-mode liquid crystal display device (dotted line) and liquid crystal display device (solid line) of Comparative Example 3 at azimuth angles Φ=135 and 315 degrees.

49A is a schematic perspective view showing an example of the scattering characteristics of the anisotropic scattering film constituting the display device of the present invention. In the figure, P represents the direction of the incident angle of 0 degrees, S represents the scattering central axis, and P(S) represents the axial direction in which the direction of the incident angle of 0 degrees coincides with the scattering central axis. In addition, the length of the arrow extending from the intersection point of the scattering center axis and the anisotropic scattering film to the bell-shaped curved surface (dotted line in the figure) indicates the amount of linearly transmitted light in each direction.

FIG. 49B is a schematic plan view of the bell-shaped curved surface that defines the amount of light transmitted through a straight line in FIG. 49A viewed from the front.

Fig. 50 is a schematic perspective view showing the structure of a conventional anisotropic scattering film.

Fig. 51 is a schematic diagram showing the scattering characteristics of a conventional anisotropic scattering film.

Symbol Description

3: Polarizer film

3a, 3b: Polarizing elements

4: WV film

10: Anisotropic scattering layer

10a: The first anisotropic scattering film

10b: The second anisotropic scattering film

11a: VA mode liquid crystal unit

11b: TN mode liquid crystal unit

11c: IPS mode liquid crystal unit

12a: The first retardation film

12b: The second retardation film

12c: The third retardation film

12d: The fourth retardation film

12e: The fifth retardation film

12f: The 6th retardation film

12g: The seventh retardation film

12h: The 8th retardation film

12j: The ninth retardation film

13a: The first polarizer

13b: The second polarizer

13c: The third polarizer

13e: The fifth polarizer

13f: 6th polarizer

13g: The seventh polarizer

13h: The 8th polarizer

13i: Polarizer with WV film

13j: The 9th polarizer

15: display device

15a: VA mode liquid crystal display device

15b: TN mode liquid crystal display device

15c: IPS mode liquid crystal display device

20: A region with a different refractive index from the peripheral region (rod-shaped solidified region)

30: Light receiving part

40: Plate-like region with a different refractive index than the peripheral region

50: light control sheet

51: Linear light source

100: display device

100a: VA mode liquid crystal display device

100b, 200b: TN mode liquid crystal display device

100c: IPS mode liquid crystal display device

a: absorption axis

A: The angle formed by the extremum azimuth M ₁ of the display device and the azimuth of the display device at an azimuth angle of 0 degrees

b: Alignment control direction of discotic liquid crystal in WV film

C: Equivalent line of light transmitted by a straight line

d: Liquid crystal alignment control direction in the liquid crystal cell

D: The direction after tilting Θ from the normal direction of the viewing surface of the display device

M ₁ : display the extremum orientation of the device

s: slow axis

S: Scattering central axis

S ₁ : Axis orientation of scattering central axis S

δ: The angle formed by the extremum orientation M ₁ of the display device and the axial orientation S ₁ of the scattering central axis

Φ: Azimuth

ω: Polar angle of scattering central axis S

Detailed ways

Next, the present invention is described in detail.

The display device of the present invention includes a display device whose contrast ratio has viewing angle dependence, and an anisotropic scattering film having an anisotropic scattering layer. The contrast ratio of the above display device has viewing angle dependence. In the present specification, the term "display device" is not particularly limited as long as it is used for display, for example, a liquid crystal display device is mentioned. The so-called contrast ratio is one of the display properties of a display device, and is usually expressed by dividing the maximum brightness by the minimum brightness. The so-called viewing angle dependence refers to the case of viewing from the front direction (the normal direction of the viewing surface of the display device, the direction with a polar angle of 0 degrees) and the case of viewing from an oblique direction (a direction with a polar angle greater than 0 degrees), In addition, even if the polar angle is the same, the display performance of the display device differs when viewed from a certain direction and when viewed from another direction. Therefore, the so-called "contrast ratio has viewing angle dependence" refers to the case of viewing from the front direction and the case of viewing from an oblique direction, and also the case of viewing from a certain direction and the case of viewing from another direction even if the polar angle is the same. case, the contrast ratio is different.

The contrast ratio of the above-mentioned display device is generally larger as it gets closer to the front direction, but it may also be reversed.

The above-mentioned anisotropic scattering film has an anisotropic scattering layer. In this specification, the term "anisotropic scattering layer" is not particularly limited as long as it exhibits anisotropic scattering characteristics (a characteristic in which the scattering characteristics change when the incident angle is changed) at least in one direction. The azimuth refers to the in-plane direction of the film surface of the anisotropic scattering film or the observation surface of the display device, and is represented by the azimuth angle Φ (0°≤Φ<360°). In addition, the term "incident angle" refers to the angle formed by the normal direction of the film surface of the anisotropic scattering film and the incident direction. Examples of the form of the above-mentioned anisotropic scattering film include a form consisting of only an anisotropic scattering layer, a form of laminating a transparent substrate on one side (observation side or back side) of an anisotropic scattering layer, A method in which transparent substrates are laminated on both sides of the anisotropic scattering layer (observation side and back side). In addition, the above-mentioned anisotropic scattering layer may have a single-layer structure or a laminated structure.

As the above-mentioned transparent substrate, it is preferable that the transparency is high. Therefore, the total light transmittance (JIS K7361-1) of the above-mentioned transparent base is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more. In addition, the haze (JIS K7136) of the above-mentioned transparent substrate is preferably 3.0 or less, more preferably 1.0 or less, still more preferably 0.5 or less. Examples of the above-mentioned transparent substrate include transparent plastic films and glass plates, but plastic films are preferable in terms of thinness, light weight, impact resistance and productivity. Examples of materials for the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetate (TAC), polycarbonate (PC), poly Aryl ester, polyimide (PI), aromatic polyamide, polysulfone (PS), polyethersulfone (PES), cellophane, polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA ), cycloolefin resin, etc. Examples of the form of the above-mentioned plastic film include a form in which the above-mentioned materials are thinned alone or mixed, and a form in which the above-mentioned film-formed materials are laminated. In consideration of application and productivity, the thickness of the transparent substrate is preferably 1 micron to 5 mm, more preferably 10 to 500 microns, and even more preferably 50 to 150 microns.

In the present invention, the above-mentioned anisotropic scattering film has a scattering central axis. In this specification, the so-called scattering center axis is an axis showing approximately symmetry about the axis direction of the anisotropic scattering characteristic. In addition, in this specification, as shown in FIG. 2B, the axial direction of the scattering central axis is directed from the back side to the observation side, and the normal direction (Z-axis direction) of the film surface is also directed from the back side to the observation side. . At this time, the angle ω formed by the axial direction of the scattering central axis S and the normal direction (Z-axis direction) of the film surface is also referred to as the polar angle of the scattering central axis S. When the above-mentioned scattering center axis S is inclined from the normal direction of the film surface (ω≠0 degree), as shown in _FIG . In the case of coincidence (ω≈0 degrees), it is considered that there is an axis orientation S ₁ in all orientations. In addition, the axial orientation _S1 of the scattering center axis also has a predetermined direction, and the direction of the axial orientation is determined corresponding to the axial direction.

The aforementioned anisotropic scattering film having a scattering center axis exhibits anisotropic scattering characteristics in all directions. Therefore, although the scattering characteristics of an anisotropic scattering film cannot be expressed uniquely, when the amount of linearly transmitted light is used as an index of scattering characteristics, for the anisotropic scattering film constituting the display device of the present invention, the linear transmission The amount of light changes approximately symmetrically around the axial direction of the scattering central axis. The linear transmission light amount is the light amount of parallel rays emitted in the same direction as the incident direction when a predetermined amount of parallel rays is made incident. As a method of measuring the amount of light transmitted in a straight line, for example, the method shown in FIG. 6 can be mentioned. In the method shown in FIG. 6 , a light receiving unit (for example, a goniophotometer) 30 is fixed at a position for receiving straight light from a light source (not shown), and a test piece 10 a is placed between the light source and the light receiving unit 30 . According to this method, for example, by rotating the test piece 10a around the L-L axis (rotation axis), the incident angle is changed in the M-M orientation (measurement orientation) perpendicular to the L-L axis in the film surface, and the linear transmitted light amount is measured. The above-mentioned measurement orientation can be appropriately changed by changing the rotation axis. Therefore, according to this method, it is possible to measure the amount of straight-line transmitted light in various directions.

In the present invention, the above-mentioned anisotropic scattering film has a scattering effect in an orientation approximately identical to an orientation (extreme orientation) in which the contrast ratio in a direction inclined at a certain angle from the normal direction of the viewing surface of the display device takes an extreme value. The central axis is arranged on the side of the viewing surface of the display device. Accordingly, since the extremum orientation of the display device is roughly consistent with the axial orientation of the scattering central axis of the anisotropic scattering film, in this extremum orientation, the scattering central axis can be the center, so that the axis approximately parallel to the scattering central axis Since the incident light is scattered in all directions and averaged, the viewing angle dependence of the contrast ratio can be improved at least in the extreme direction. In addition, the above-mentioned anisotropic scattering film shows anisotropic scattering characteristics in all directions as described above, so the light in the axial direction deviated from the scattering center axis or in the direction with a large incident angle is only weakly scattered, and basically Therefore, it is possible to suppress the deterioration of the display quality due to scattering of incident light in the direction where the contrast ratio is high.

Furthermore, in general display devices, various display properties such as γ curve and chromaticity are optimally designed in the direction where the contrast ratio is the largest, and the viewing angle dependence of these display properties shows the same tendency as the viewing angle dependence of the contrast ratio. Therefore, according to the present invention, the viewing angle dependence of various display properties such as the gamma curve and chromaticity can also be generally improved. In addition, according to this mechanism, the effects of the present invention are not limited by the white display state or the black display state, and can be obtained without changing the design of the basic structure of any display device whose display performance has viewing angle dependence.

Hereinafter, "the direction in which the contrast ratio takes an extreme value (extreme value direction)" in a direction inclined by a certain angle from the normal direction of the viewing surface of the display device will be described in detail with reference to FIGS. 1A to 1C.

FIG. 1A is a schematic diagram illustrating “the direction inclined at a certain angle from the normal direction of the viewing surface of the display device”.

In FIG. 1A , the dotted line shows the direction of the polar angle Θ, and the dotted line arrow shows the normal direction of the viewing surface of the display device 15 . The so-called "direction inclined by a certain angle Θ from the normal direction of the viewing surface of the display device" refers to all directions D with a polar angle Θ, and the direction D points from the back side to the viewing surface side.

The normal direction of the viewing surface of the display device 15 is generally consistent with the normal direction of the viewing surface (Z-axis direction) of the display device and the normal direction of the film surface of the anisotropic scattering film.

FIG. 1B is a schematic diagram illustrating an orientation of a display device.

As shown in FIG. 1B , the azimuth of the display device 15 is represented by an azimuth Φ (0°≤Φ<360°). In addition, in this specification, the direction of Φ=0 degrees is called the right direction, the direction of Φ=90 degrees is called the upward direction, the direction of Φ=180 degrees is called the left direction, and the direction of Φ=270 degrees is called the downward direction . In addition, as can be seen from Figures 1A and 1B, the direction of the azimuth Φ and the polar angle -Θ (0 degrees ≤ Θ <90 degrees) is the same as the direction of the azimuth Φ+180 degrees (the direction opposite to the orientation of the azimuth Φ) and the polar angle Θ direction is exactly the same. In this specification, the value range of the polar angle is usually set above 0 degrees, thereby distinguishing the direction of the azimuth Φ and the direction of the azimuth Φ+180 degrees, and each direction is specified by specifying the azimuth Φ (0 degrees≤Φ< 360 degrees) and polar angle Θ (0 degrees ≤ Θ <90 degrees).

FIG. 1C is a schematic diagram illustrating extremum orientations of a display device.

The so-called "extreme orientation of the display device" refers to the orientation corresponding to the apex of the mountain-shaped curve ( The orientation where the contrast ratio takes the maximum value. The following is also referred to as the "maximum orientation" or "the maximum orientation of the display device."), or the orientation equivalent to the bottom of the valley-shaped curve (the orientation where the contrast ratio takes the minimum value. Below Also known as "minimum orientation" or "minimum orientation of a display device".). For example, in FIG. 1C , A1 to A4 correspond to maximum azimuths, and B1 to B4 correspond to minimum azimuths.

The number of maximal orientations of the above-mentioned display device is not particularly limited, but as shown in FIG. 1C , it is usually four. The number of minimal orientations of the display device is not particularly limited, but as shown in FIG. 1C , it is usually four. For example, in a liquid crystal display device in which a pair of polarizers are arranged on the back of the liquid crystal cell in such a way that their absorption axes (transmission axes) are perpendicular to each other (Cross-Nicol configuration), In the case of observing the axial direction of the absorption axis (transmission axis), even if the viewing angle is increased (even if the polar angle is increased), the angle formed by the absorption axes (transmission axes) does not deviate from 90 degrees, so the contrast ratio can be maintained higher and unchanged. Therefore, in this case, four axial orientations of the absorption axis (transmission axis) of the polarizing plate are considered to be maximum orientations. On the contrary, in the case of viewing from four directions of the angle formed by the absorption axis and the transmission axis of the bisected polarizer, if the viewing angle is increased, the angles formed by the absorption axes (transmission axes) deviate from each other by 90° degree, so the contrast ratio becomes lower. These four orientations are considered to be the orientation corresponding to the bottom of the valley-shaped curve (minimum orientation) in the curve showing the azimuth angle dependence of the contrast ratio in the direction inclined by a certain angle from the normal direction of the viewing surface of the display device. .

In addition, in this specification, the term "substantially coincides" includes not only a state of coincidence, but also a state that can be regarded as a state of coincidence in view of the effect of the present invention. In addition, in this specification, the term "approximately parallel" includes not only a parallel state, but also a state that can be regarded as a parallel state in view of the effect of the present invention.

As mentioned above, the scattering center axis (i) can be roughly consistent with the normal direction of the viewing surface of the display device, and (ii) can also be roughly consistent with the extremum orientation of the display device from the normal direction of the viewing surface of the display device. Azimuth tilt. Therefore, the polar angle ω of the scattering central axis is not particularly limited as long as it is 0° or more and less than 90°, but is preferably 0° or more and less than 60°. In addition, from the viewpoint of improving the display quality of TN-mode liquid crystal display devices, etc., the polar angle ω of the scattering central axis is preferably approximately 0 degrees, and from the viewpoint of improving the display quality in the direction with a large polar angle in a specific orientation See, it is preferably not less than 30 degrees and not more than 50 degrees.

In the anisotropic scattering film having a scattering center axis in a direction inclined from the normal direction of the observation surface of the above-mentioned display device, usually on the axial direction of the scattering center axis, the amount of light transmitted by a straight line is within the angle of incidence η (-90 degrees <η<90 degrees) is greater than the polar angle ω of the scattering central axis (0 degrees≤ω<90 degrees) (ω<η<90 degrees) and smaller (-90 degrees<η<ω), depending on The angle of incidence varies roughly similarly. For example, according to an anisotropic scattering film having a scattering central axis in the direction of a polar angle of 30 degrees, as shown in FIG. When the incident angle increases, the amount of light changes as shown by drawing a small hill. Conversely, in the direction where the polar angle is smaller than 30 degrees, it changes as shown by drawing a large mountain while the incident angle decreases.

In addition, in the above-mentioned anisotropic scattering film having a scattering center axis in the direction inclined from the normal direction of the viewing surface of the display device, usually in the direction perpendicular to the axis orientation of the scattering center axis, at the incident angle η(- 90°<η<90°) in the direction greater than 0° and in the direction smaller than 0°, the amount of transmitted light in a straight line depends on the incident angle and changes approximately symmetrically. For example, according to an anisotropic scattering film having a scattering central axis in the direction of a polar angle of 30 degrees, as shown in FIG. In the small direction, the amount of transmitted light in a straight line changes approximately symmetrically depending on the incident angle.

The arrangement state of the above-mentioned anisotropic scattering film and the display device is not particularly limited, but it is preferable to bond the anisotropic scattering film to the display device. The method of bonding the above-mentioned anisotropic scattering film to the display device is not particularly limited, and examples thereof include a method using an adhesive and a method using an adhesive.

The configuration of the display device of the present invention is not particularly limited as long as it has the above-mentioned display device and the anisotropic scattering film as constituent elements, and may or may not have other constituent elements.

From the viewpoint of effectively obtaining the effects of the present invention, the smaller the amount of light transmitted in a straight line in the axial direction of the scattering central axis of the above-mentioned anisotropic scattering film, the better.

Next, preferred embodiments of the display device of the present invention will be described in detail.

The aforementioned extreme value is preferably a maximum value. That is, the orientation in which the contrast ratio in a direction inclined at a certain angle from the normal direction of the viewing surface of the display device takes an extreme value is preferably the maximum orientation of the display device. Accordingly, by disposing the anisotropic scattering film on the viewing surface side of the display device, the axis orientation of the scattering central axis is approximately consistent with the maximum orientation of the display device, thereby making the axial direction approximately parallel to the scattering central axis The incident light (white luminance) is scattered (diffused) in all directions centered on the scattering center axis and averaged, so that the contrast ratio can be improved at least in the maximum direction approximately coincident with the axis orientation of the scattering center axis. Viewpoint dependence.

When the above-mentioned display device is a liquid crystal display device of VA mode or IPS mode, it is preferable that the maximum azimuths are four directions such as azimuth angle Φ=0, 90, 180, and 270 degrees. When the above-mentioned display device is a liquid crystal display device of TN mode or OCB mode, it is preferable that the maximum azimuths are four directions such as azimuth angle Φ=45, 135, 225, and 315 degrees. In addition, when the above-mentioned display device has two or more maximum orientations, the above-mentioned anisotropic scattering film only needs to have a scattering center axis in an orientation substantially coincident with one of the maximum orientations of the display device.

The aforementioned extreme value is preferably a minimum value. That is, the orientation in which the contrast ratio in a direction inclined at a certain angle from the normal direction of the viewing surface of the display device takes an extreme value is preferably the minimum orientation of the display device. Accordingly, by arranging the anisotropic scattering film on the viewing surface side of the display device so that the axis orientation of the scattering central axis is approximately consistent with the minimum orientation of the display device, the axis approximately parallel to the scattering central axis can be made Directly incident light (black luminance) is scattered (diffused) in all directions centered on the scattering center axis and averaged, so the contrast ratio can be improved at least in the minimum orientation that roughly coincides with the axis orientation of the scattering center axis viewing angle dependence.

When the above-mentioned display device is a liquid crystal display device of VA mode or IPS mode, it is preferable that the minimum azimuth is four directions such as azimuth angle Φ=45, 135, 225, and 315 degrees. When the above-mentioned display device is a liquid crystal display device of TN mode or OCB mode, it is preferable that the minimum azimuth is four directions such as azimuth angle Φ=0, 90, 180, and 270 degrees. In addition, when the display device has two or more minimum orientations, the anisotropic scattering film only needs to have a scattering center axis in an orientation substantially coincident with one of the minimum orientations of the display device.

When the display device has a plurality of extremum orientations, which extremum orientation is preferably substantially coincident with the axial orientation of the scattering central axis varies depending on the arrangement location of the display device and the like. For example, a display device having a display device having four orientations of the azimuth angles Φ=0, 90, 180, and 270 degrees in the maximum azimuth and 4 orientations of the azimuth angles Φ=45, 135, 225, and 315 degrees in the minimum azimuth is being used. When used in a car navigation that requires high visibility in a specific direction such as the direction of the driver's seat (right direction), the anisotropic scattering film is preferably used in conjunction with the display in a car navigation that is placed at the driver's eye level. There is a scattering central axis in an azimuth in which the maximum azimuth of the device (the azimuth angle Φ=0 degrees) is substantially the same. In addition, in the type of car navigation that is placed at a position lower than the driver's line of sight, etc., the anisotropic scattering film is preferably in an orientation that approximately coincides with the minimum orientation of the display device (the orientation of the azimuth angle Φ = 45 degrees). Has a scatter central axis.

The above-mentioned anisotropic scattering film preferably has a scattering central axis in an orientation substantially coincident with an orientation in which the contrast ratio in a direction inclined at a fixed angle of 20 degrees or more from the normal direction of the viewing surface of the display device takes an extreme value. In addition, the above-mentioned anisotropic scattering film more preferably has a scattering central axis in an orientation substantially coincident with an orientation in which the contrast ratio in a direction inclined at 45 degrees from the normal direction of the viewing surface of the display device takes an extreme value. By measuring the contrast ratio in the direction inclined by a certain angle (hereinafter referred to as "measurement angle") from the normal direction of the viewing surface of the display device, a curve representing the azimuth angle dependence of the contrast ratio as shown in FIG. 1C is made, Thus, the extremum orientation of the display device can be obtained. In the present invention, the measurement angle is not particularly limited as long as it is larger than 0° and smaller than 90°. However, as shown in FIG. 3 , in general display devices such as liquid crystal display devices, when the measurement angle is about 10 degrees, the contrast ratio is uniformly high in all directions, and it may be difficult to judge whether the contrast ratio is maximum or extreme. Small. From this point of view, the measurement angle is preferably 20 degrees or more, more preferably 45 degrees.

Therefore, in the present invention, although the axial orientation of the above-mentioned scattering central axis should roughly coincide with any one of the extreme orientations of the display device, it is preferable that the axis orientation of the display device obtained at a certain angle at which the measurement angle is 20 degrees or more The extremum azimuth of is approximately the same, and more preferably substantially coincides with the extremum orientation of the display device obtained at a measurement angle of 45 degrees.

The extremum azimuth of the display device can also vary in number or azimuth depending on the measurement angle.

The anisotropic scattering layer preferably cures a composition containing a photocurable compound. This makes it possible to easily manufacture an anisotropic scattering film having the above-mentioned anisotropic scattering property, that is, an anisotropic scattering film showing anisotropic scattering property in all directions. When the cross-section of the anisotropic scattering layer cured by the above-mentioned composition is observed under a microscope, for example, a fine structure extending in an oblique direction may be observed. At this time, as shown in FIG. 2A , it is considered that in the interior of the anisotropic scattering layer 10 , many minute rod-shaped solidified regions 20 having a refractive index slightly different from those of the peripheral regions are formed in oblique directions. In addition, at this time, as shown in FIG. 2B , the scattering center axis S of the anisotropic scattering film constituting the display device of the present invention is inclined relative to the normal direction (Z-axis direction) of the viewing surface of the display device, but it is considered that the axis direction is different from that in FIG. The extending directions of the rod-shaped solidified regions 20 in 2A are in a parallel relationship. Also, in this case, the inclined scattering _center axis S has an axial orientation S ₁ projected on the XY plane as shown in FIG. The directions of the shadows at the time of up are in a parallel relationship. Therefore, it is considered that the anisotropic scattering properties of the above-mentioned anisotropic scattering film originate from the internal structure of the anisotropic scattering layer. Although the shape of the rod-shaped solidified region 20 is shown as a column in FIG. 2A , it is not particularly limited. In addition, in FIG. 2A, as one of the preferred examples, the rod-shaped solidified region 20 extends in an oblique direction, but the extending direction of the rod-shaped solidified region 20 is the same as the axial direction of the scattering central axis, and is not particularly limited. In addition, although the shape of the anisotropic scattering layer is shown as flakes in FIG. 2A , it is not particularly limited.

Examples of the form of the composition containing the photocurable compound include (A) a form in which a photopolymerizable compound is alone, (B) a form in which a plurality of photopolymerizable compounds are mixed, (C) a form in which a single or multiple photopolymerizable compounds are mixed, A photopolymerizable compound and a non-photopolymerizable polymer resin, etc. According to the aspects (A) to (C) above, as a result of forming micron-order microstructures (rod-shaped solidified regions) with different refractive indices in the anisotropic scattering layer by light irradiation as described above, it is considered that The incident angle dependence of the amount of transmitted light in the above-mentioned straight line was found.

Therefore, the individual photopolymerizable compounds in the above (A) and (C) embodiments have a large change in refractive index before and after photopolymerization. Moreover, as several photopolymerizable compounds in the aspect of said (B) and (C), it is preferable that it is the combination which differs in the refractive index after hardening. In addition, as the photopolymerizable compound and the non-photopolymerizable polymer resin in the above-mentioned (C) embodiment, a combination having a different refractive index after curing is preferable. In addition, from the viewpoint of effectively obtaining the effects of the present invention, the change in refractive index and the difference in refractive index are preferably 0.01 or more, more preferably 0.05 or more, and still more preferably 0.10 or more.

In addition, the photocurable compound is preferably a photopolymerizable compound (radical polymerizable compound or cation polymerizable compound) containing a polymer, an oligomer, or a monomer having a radical polymerizable or cationic polymerizable functional group and a photoinitiator. (photopolymerization initiator), which has the property of polymerizing and curing by irradiating ultraviolet rays and/or visible rays.

The above-mentioned radical polymerizable compounds mainly contain one or more unsaturated double bonds in the molecule. Specifically, examples thereof include epoxy acrylates, urethane acrylates, polyester acrylates, and silicone-acrylates. Name of acrylic oligomer (acrylicoligomer), and 2-ethylhexyl acrylate, phenoxyethyl acrylate, iso-norbornyl (isonorbornyl) acrylate, 2-hydroxyethyl acrylic acid, 2,2,2 - Trifluoroethyl methacrylate, 2-perfluorooctyl-ethyl acrylate, triethylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, tri Acrylate monomers such as methylolpropane triacrylate, ethylene oxide (EO)-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, etc. .

As the above-mentioned cationically polymerizable compound, a compound containing one or more epoxy groups, vinyl ether groups and/or oxetane groups in the molecule can be used. Examples of compounds containing an epoxy group in the molecule include bisphenol A, hydrogenated bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, Diglycidyl ethers of bisphenols such as tetrachlorobisphenol A and tetrabromobisphenol A, novolac (phenol novolac), cresol novolac, novolac bromide, o-cresol novolac Polyglycidyl ethers of novolak resins, ethylene glycol, butanediol, 1,6-hexanediol, neopentyl glycol, trimethylolpropane, ethylene oxide (EO) of bisphenol A Additives such as diglycidyl ethers of alkylene glycols, glycidyl esters of cyclohexanephthalic acid, glycidyl esters such as diglycidyl esters of dimer acids, and the like. In addition, alicyclic epoxy compounds such as 3,4-epoxycyclohexanemethyl-3',4'-epoxycyclohexylcarboxylate, 1,4-bis[(3-ethyl Oxetane compounds such as 3-oxetanylmethoxy)methyl]benzene, 3-ethyl-3-(hydroxymethyl)-oxetane, diethylene glycol divinyl Ether, vinyl ether compounds such as trimethylolpropane trivinyl ether, etc.

The above-mentioned photopolymerizable compound is not limited to the above-mentioned ones. In addition, in order to generate a sufficient refractive index difference, fluorine atoms (F) can also be introduced into the above-mentioned photopolymerizable compound to achieve a low refractive index. Sulfur atoms (S), bromine atoms (Br), and various metals can be introduced. atoms to achieve high refractive index. In addition, in order to increase the refractive index of the above-mentioned anisotropic scattering layer, high refractive index metals such as titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and tin oxide (SnO _x ) are added to the photopolymerizable compound. Functional ultrafine particles in which photopolymerizable functional groups such as acrylic groups or epoxy groups are introduced into the surface of ultrafine particles made of oxides are also effective.

As a photoinitiator capable of polymerizing the above radical polymerizable compound, for example, benzophenone, 2,4-diethylthiazolone, benzoin isopropyl ether, 2,2-diethoxyacetophenone, Benzyl dimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-Hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1,1-[4-(2-hydroxyethoxy )-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, bis(cyclopentadienyl)-bis(2,6-difluoro-3-pyrrolysine (pyl) -1-yl)titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2,4,6-trimethylbenzoylbiphenyl Phosphate Hydroxide etc.

The photoinitiator capable of polymerizing the cationically polymerizable compound is a compound that generates oxygen by light irradiation and polymerizes the above-mentioned cationically polymerizable compound by using the generated oxygen. Usually, onium salt (onium salt) and metallocene complex are preferably used. compound. As the onium salt, diazonium salt, sulfonium salt (sulfonium salt), iodonium salt, phosphorus salt, selenium salt, etc. are used, and among these counter ions, tetrafluoroborate ion (BF ₄ ⁻ ), hexafluorophosphate ion Anions such as (PF ₆ ^- ), hexafluoroarsenate ion (AsF ₆ ^- ), hexafluoroantimonate ion (SbF ₆ ^- ). As the photoinitiator of the cationic polymerizable compound, for example, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-methoxyphenyl)phenyliodonium hexafluoroantimonate, Bis(4-tert-butylphenyl)iodonium hexafluorophosphate, (η5-cumene)(η5-cyclopentadienyl)iron(II) hexafluoropyrophosphate, etc.

The photoinitiator is preferably blended in an amount of not less than 0.01 parts by weight and not more than 10 parts by weight with respect to 100 parts by weight of the photopolymerizable compound. If the above-mentioned photoinitiator is less than 0.01 parts by weight, the photocurability may be low, and if it exceeds 10 parts by weight, only the surface may be cured and the internal curability may be low. The photoinitiator is more preferably blended in an amount of 0.1 to 7 parts by weight, more preferably 0.1 to 5 parts by weight, relative to 100 parts by weight of the photopolymerizable compound.

Examples of polymer resins that do not have photopolymerization in the above (C) embodiment include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, Vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, etc. These polymer resins must have sufficient compatibility with the photopolymerizable compound before photopolymerization, and various organic solvents, plasticizers, etc. may be used in order to ensure such compatibility. When using acrylate as the photopolymerizable compound, it is preferable to select a polymer resin from acrylic resins from the viewpoint of compatibility.

The method of curing the above-mentioned composition is not particularly limited, but for example, the above-mentioned composition is provided in a sheet form on a substrate and irradiated with parallel rays (ultraviolet rays, etc.) from a predetermined direction. Thereby, an aggregate of a plurality of rod-shaped cured regions extending in parallel along the irradiation direction of parallel light rays can be formed (for example, refer to FIG. 2A ).

As a method of forming the above-mentioned composition in a sheet form on a substrate, a usual painting method (coating) or printing method can be used. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse roll coating, transfer roll coating can be used. Transfer roll coating, gravure roll coating, kiss roll coating, cast coating, spray coating, slotorifice coating, calender Application methods such as calendar coating, dam coating, dip coating, die coating, etc., gravure printing such as gravure printing, screen printing, etc. Printing methods such as stencil printing. In addition, when the viscosity of the above-mentioned composition is low, a method of providing a structure with a predetermined height around the substrate and applying a liquid composition to the region surrounded by the structure may be used.

As a light source for irradiating the above-mentioned parallel rays (ultraviolet rays, etc.), a short-arc ultraviolet lamp is generally used, and specifically, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like can be used. The device for irradiating parallel rays (ultraviolet rays, etc.) from a predetermined direction is not particularly limited, but a device capable of irradiating parallel rays (ultraviolet rays, etc.) of uniform intensity to a certain area can be selected from commercially available devices. It is preferable to use an exposure apparatus for resist exposure. When forming an anisotropic scattering layer having a small size, a method of using an ultraviolet spot light source as a point light source and irradiating it from a sufficiently separated distance may be used.

The parallel light irradiated to the material for forming the above-mentioned composition into a sheet must include wavelengths capable of polymerizing and curing the photopolymerizable compound, and light having a wavelength centered at 365 nm of a mercury lamp is generally used. When the anisotropic scattering layer is formed using light in this wavelength band, the emission intensity is preferably not less than 0.01 mW/cm ² and not more than 100 mW/cm ² . If the luminous intensity is less than 0.01mW/cm ² , it will take a long time to cure, so there is a concern that the production efficiency will deteriorate. If it exceeds 100mW/cm ² , the curing of the photopolymerizable compound will be too fast and no structure will be formed. Anisotropic scattering properties. The above-mentioned emission intensity is more preferably not less than 0.1 mW/cm ² and not more than 20 mW/cm ² .

The above-mentioned anisotropic scattering film preferably has a direction in which the amount of linearly transmitted light is equal to or less than the amount of linearly transmitted light in the axial direction of the scattering central axis. The contrast ratio in the direction inclined at a certain angle is consistent with the orientation of the extreme value. Directions in which the amount of linear transmitted light is equal to or less than the amount of linear transmitted light in the axial direction of the scattering central axis are generally close to the axial direction of the scattering central axis, and are arranged approximately radially around the axial direction of the scattering central axis. Accordingly, it is possible to obtain the same or better effects than the case where the axis orientation of the scattering center axis coincides with the extreme orientation of the display device.

4 is an explanatory diagram showing the relationship between the axial orientation of the scattering central axis of the anisotropic scattering film constituting the display device of the present invention and the extreme value orientation of the display device. The two solid arrows in the figure represent the extremum orientation M ₁ of the display device and the axial orientation S ₁ of the scattering central axis respectively. A represents the angle formed by the extremum azimuth _M1 of the display device and the azimuth of the display device at an azimuth angle of 0 degrees, and δ represents the angle formed by the extremum azimuth _M1 of the display device and the axis azimuth _S1 of the scattering central axis.

Next, the display device of the present invention will be described with reference to FIG. 4 , but the display device of the present invention is not limited to the structure shown in FIG. 4 . For example, the arrangement relationship between the extremum orientation M ₁ of the display device and the axial orientation S ₁ of the scattering central axis is not limited to the relationship shown in FIG. 4 .

The angle (δ) formed between the axis orientation of the above-mentioned scattering central axis and the orientation in which the contrast ratio in the direction inclined by a certain angle from the normal direction of the viewing surface of the display device takes an extreme value (extreme orientation) is preferably 15 degrees or less. If the angle formed by the axial orientation of the scattering central axis and the maximum orientation of the display device exceeds 15 degrees, the black luminance in the direction of high black luminance will be scattered, and the black luminance in the direction of high contrast ratio will become high, which may increase the contrast ratio. The direction of the contrast ratio decreases. Also, if the angle formed by the axis orientation of the scattering central axis and the minimum orientation of the display device exceeds 15 degrees, the amount of scattered black luminance decreases, and it may be difficult to obtain the effect of improving the contrast ratio.

For example, the anisotropic scattering film showing the scattering characteristics of FIG. 5 shows the same axis direction as the scattering center axis (the direction where the incident angle is 0 degrees) or The amount of light transmitted through the line below it. Therefore, by setting the angle (δ) formed by the axial orientation of the scattering central axis and the extreme orientation of the display device to be 15 degrees or less, the anisotropic scattering film can be formed at the extremes of the display device approximately in line with the axial orientation of the scattering central axis. In the value direction, sufficient diffusion performance can be exhibited, so the effect of the present invention can be obtained. Also, as shown in FIG. 5 , the amount of linearly transmitted light in a direction in which the incident angle exceeds the range of -15° to 15° is larger than that in the axial direction of the scattering central axis. Therefore, if the axis orientation of the scattering central axis and the extreme orientation of the display device form an angle (δ) of more than 15 degrees, the anisotropic scattering film is on the extreme orientation of the display device that is approximately consistent with the axis orientation of the scattering central axis. , cannot exert sufficient diffusion performance, and worry that in this extreme orientation, the viewing angle dependence of the contrast ratio of the display device still appears as the viewing angle dependence of the contrast ratio of the display device.

The angle (δ) formed by the axis orientation of the above-mentioned scattering central axis and the orientation (extreme orientation) in which the contrast ratio in the direction inclined by a certain angle from the normal direction of the viewing surface of the display device is more preferably 10 degrees or less, Even more preferably, it is 5 degrees or less. Therefore, since the axial orientation of the scattering central axis is more consistent with the extreme orientation of the display device, the maximum contrast ratio or the contrast ratio of orientations other than the extreme orientation approximately coincident with the axial orientation of the scattering central axis will not be greatly reduced. The viewing angle dependence of the contrast ratio can be further improved in the extreme orientation of the display device, which at least substantially coincides with the axial orientation of the scattering central axis.

The angle (δ) formed by the axis orientation of the above-mentioned scattering central axis and the orientation of the extreme value of the contrast ratio in the direction inclined by more than 20 degrees from the normal direction of the viewing surface of the display device is preferably 15 degrees or less, which is consistent with the observation from the display device. The angle (δ) formed by the azimuths where the contrast ratio in the direction inclined by 45 degrees to the surface normal direction takes an extreme value is preferably 15 degrees or less.

In the above-mentioned anisotropic scattering film, the angle formed between the direction with the smallest amount of straight-line transmitted light and the axial direction of the scattering center axis is preferably smaller than the angle formed between the direction with the largest amount of straight-line transmitted light and the axial direction of the scattering center axis. This assumes that the angle formed by the direction of the minimum amount of light transmitted by a straight line and the axial direction of the scattering central axis is α, and the angle formed by the direction of the largest amount of transmitted light by a straight line and the axial direction of the scattering central axis is β, with 0 degrees ≤ α < β said. In general, the polar angle of a display device in a direction with a large contrast ratio is smaller than that in a direction with a small contrast ratio. Therefore, according to this, the light in the direction with a high contrast ratio of the display device is scattered more strongly than the light in a direction with a small contrast ratio, so that the effects of the present invention can be more effectively obtained.

As a more preferable form of the above-mentioned anisotropic scattering film, in the graph showing the incident angle-linear transmitted light amount, the curve (i) showing the incident angle dependence of the scattering characteristic becomes substantially W-shaped. Form (for example, refer to FIG. 5.), (ii) becomes the form of a substantially U-shape. Next, an anisotropic scattering film having the mode (i) and having a scattering central axis in the direction normal to the film surface will be described as an example.

In the case of the anisotropic scattering film having the mode (i) above, in which the scattering center axis is in the normal direction of the film surface, although the amount of transmitted light in a straight line is in the axial direction of the scattering center axis (the normal direction of the film surface) It is sufficiently small, but gradually decreases as the angle (magnitude of incident angle) with the axial direction of the scattering central axis becomes larger, and shows the minimum value in the direction of the incident angle of 5 to 20 degrees (α). In the direction where the incident angle is larger than α, the larger the incident angle is, the larger the amount of straight light transmission is, and the maximum value is shown in the direction where the incident angle is 40 to 65 (β). In addition, in the direction in which the magnitude of the incident angle is larger than β, the amount of light transmitted in a straight line decreases as the magnitude of the incident angle increases. The incidence angle dependence of such scattering characteristics is obtained approximately the same in all directions, that is, the graph showing the incidence angle-linear transmitted light quantity is centered on the scattering center axis (the axis where the incidence angle is 0 degrees), and shows approximately Symmetry (see, for example, Figure 5.).

In addition, the axial direction of the above-mentioned scattering center axis and the range of the incident angle in which the amount of straight-line transmitted light shows the minimum value or the maximum value are examples and are not limited thereto. In the aspect (i), the linear transmitted light amount in the axial direction of the scattering center axis is preferably as small as possible, and the above-mentioned embodiment (ii) has the smallest linear transmitted light amount in the axial direction of the scattering central axis.

The incidence angle dependence of the scattering characteristics of the anisotropic scattering film having the above-mentioned (ii) mode is represented by a vector starting from one emission point to represent the amount of transmitted light and its advancing direction on a straight line, and connecting the top parts of the vector to represent all directions In the case of incident light rays, as shown in FIGS. 49A and 49B , it is preferable to obtain a bell-shaped curved surface with the axial direction of the scattering central axis as the central axis of symmetry (dotted line in the figure). By exhibiting the above-mentioned anisotropic scattering characteristics in the anisotropic scattering film, the viewing angle dependence of the contrast ratio can be improved in a wide range of directions including the extreme value direction while reducing the decrease in the maximum contrast ratio particularly. In addition, the effect of improving the viewing angle dependence of the contrast ratio can be obtained uniformly in all azimuths. And, the above-mentioned effect can be obtained by making the normal direction of the viewing surface of the display device coincide with the normal direction of the film surface of the anisotropic scattering film, that is, bonding the display device and the anisotropic scattering film, so the above-mentioned Effect.

In the aspects (i) and (ii) above, the range of the incident angle in which the amount of linearly transmitted light is equal to or less than a predetermined value may be wide. According to this, since the light in the broad direction with a high contrast ratio of the display device is scattered more intensively than the light in a direction with a small contrast ratio, the effects of the present invention can be more effectively obtained.

In the case of an anisotropic scattering film, the angle formed by the direction in which the amount of light transmitted through the straight line is the smallest and the axial direction of the scattering central axis is preferably close to 0 degrees. In addition, the minimum value of the above-mentioned linear transmitted light amount is preferably 50% or less of the maximum value, more preferably 30% or less, and still more preferably 20% or less.

In the above-mentioned anisotropic scattering film, it is preferable that the polar angle in the direction in which the amount of linearly transmitted light is the smallest is smaller than the polar angle in the direction in which the amount of linearly transmitted light is the largest in any direction. In general, the direction in which the contrast ratio of the above-mentioned display device is high is smaller than the direction in which the contrast ratio is small. Accordingly, in the above orientation, the light in the direction with a high contrast ratio of the display device is more strongly scattered than the light in a direction with a low contrast ratio, so that the effect of the present invention can be more effectively obtained.

From the viewpoint of more effectively obtaining the effects of the present invention, the anisotropic scattering film preferably has a smaller polar angle in the direction in which the amount of linearly transmitted light is the smallest than in the direction in which the amount of linearly transmitted light is the largest in all directions.

The above-mentioned anisotropic scattering film is preferably in the axial direction of the scattering central axis, and the maximum value of the transmitted light amount of a straight line in a direction with a polar angle larger than the scattering central axis is smaller than that of a straight line transmitted light in a direction with a polar angle smaller than the scattering central axis. the maximum value. In this method, the so-called "direction with a larger polar angle than the scattering central axis" is a direction whose orientation is the same as that of the scattering central axis and whose polar angle is larger than that of the scattering central axis, and "a direction with a polar angle smaller than the scattering central axis" The "direction" is not only a direction whose orientation is the same as the axial orientation of the scattering central axis and whose polar angle is smaller than that of the scattering central axis, but also a direction whose orientation is opposite to the axial orientation of the scattering central axis. In the present invention, the above-mentioned anisotropic scattering film is arranged such that the axial orientation of the scattering central axis substantially coincides with the extreme value orientation of the display device. Therefore, according to this, without impairing the display quality in the direction opposite to the axial direction of the scattering central axis, by scattering the light (white luminance or black luminance) in a direction with a high contrast ratio centering on the scattering central axis, it can be compared with the scattering. The viewing angle dependence of the contrast ratio is further improved in the extreme value orientation of the display device in which the axial orientations of the central axes are approximately the same.

As a more preferable form of the above-mentioned anisotropic scattering film, (iii) in the direction perpendicular to the axis direction of the scattering center axis, the polar angle of the direction in which the amount of light transmitted through the line is the smallest is greater than that in the direction in which the amount of light transmitted through the line is the largest. The way the polar angle is small. According to this aspect, the display quality in the extreme direction of the display device whose axial direction substantially coincides with the scattering central axis can be improved without impairing the display quality in the direction perpendicular to the scattering central axis. The above method (iii) will be described by taking FIG. 7 as an example. The axial direction of the above-mentioned scattering central axis and the range of incident angles in which the amount of straight-line transmitted light shows a minimum value or a maximum value are examples and are not limited to those shown in FIG. 7 .

Fig. 7 is a graph showing an example of the incident angle dependence of the scattering characteristics of the anisotropic scattering film constituting the display device of the present invention.

In the anisotropic scattering film shown in FIG. 7, the polar angle ω of the scattering central axis is 30 degrees. That is, in the anisotropic scattering film of FIG. 7, since the polar angle ω of the scattering central axis is large, the incident angle dependence of the amount of light transmitted in a straight line is large in the axial direction of the scattering central axis and the direction perpendicular to the axis. Are not the same.

First, the incident angle dependence of the scattering characteristics in the axial direction of the scattering central axis will be described. In the direction where the polar angle is larger than the central axis of scattering, although the amount of transmitted light in a straight line is sufficiently small in the axial direction of the central axis of scattering (the direction where the incident angle is 30 degrees), it gradually decreases as the incident angle increases. The angle is the smallest in the direction of 30-40 degrees. In the direction where the incident angle is larger than 30 to 40 degrees, the larger the incident angle is, the larger the amount of straight light transmission is, and the maximum is in the direction where the incident angle is 50 to 60 degrees. In addition, in the direction where the incident angle is larger than 50 to 60 degrees, the larger the incident angle is, the smaller the amount of linearly transmitted light is. In addition, in the direction where the polar angle is smaller than the scattering central axis, it gradually decreases as the incident angle becomes smaller, and becomes the smallest in the direction where the incident angle is 15 to 25 degrees. In the direction where the incident angle is smaller than 15 to 25 degrees, the smaller the incident angle is, the larger the amount of straight light transmission is, and the maximum is in the direction where the incident angle is -55 to -45 degrees. In addition, in the direction where the incident angle is smaller than -55 to -45 degrees, the smaller the angle is, the smaller the amount of light transmitted in a straight line is.

Next, the incidence angle dependence of the scattering characteristics in the azimuth on the axis direction perpendicular to the above-mentioned scattering central axis will be described. In this orientation, since the amount of linear transmitted light shows a similar tendency in the direction with the incident angle larger than 0 degrees and the direction with the incident angle smaller than 0 degrees, only the direction with the incident angle larger than 0 degrees will be described. The amount of transmitted light in a straight line is the smallest in the direction where the incident angle is 0 to 10 degrees. In the direction where the incident angle is larger than 0 to 10 degrees, the larger the incident angle is, the larger the amount of straight light transmission is, and the maximum is in the direction where the incident angle is 55 to 65 degrees. In addition, in the direction where the incident angle is larger than 55 to 65 degrees, the larger the angle is, the smaller the amount of light transmitted in a straight line is.

From the viewpoint of effectively obtaining the effect of the present invention, the smaller the amount of linearly transmitted light in the axial direction of the scattering center axis, the better. The linearly transmitted light amount is preferably the smallest in the axial direction of the scattering center axis.

The above-mentioned display device is preferably a liquid crystal display device. Thereby, the viewing angle dependence of the contrast ratio can be improved in the extreme orientation of the liquid crystal display device that substantially coincides with the axial orientation of the scattering center axis while achieving thinner, lighter, and lower power consumption of the display device. Therefore, the display device of the present invention can be applied to car navigation, etc. that require high visibility in a specific direction such as the direction of the driver's seat.

The above-mentioned liquid crystal display device may be a transmissive liquid crystal display device, a transflective dual-purpose (semi-transmissive) liquid crystal display device, or a reflective liquid crystal display device.

The liquid crystal display device described above preferably has a liquid crystal cell including a liquid crystal sandwiched between a pair of substrates, and a polarizing plate including a supporting film and a polarizing element. The liquid crystal display device having such a method is at least derived from the refractive index anisotropy of the liquid crystal or the polarized light absorption and polarized light transmission characteristics of the polarizer, and the viewing angle dependence of the contrast ratio is found. Therefore, by arranging the aforementioned anisotropic scattering film on the observation side of such a liquid crystal display device, the viewing angle dependence of the contrast ratio of the liquid crystal display device can be improved. As described above, in a liquid crystal display device in which a pair of polarizers are arranged (crossed Nicol arrangement) on the front and back surfaces of a liquid crystal cell so that their absorption axes (transmission axes) are perpendicular to each other, usually the poles of the liquid crystal display device The large orientation is consistent with the four absorption axes (transmission axes) of the polarizer, and the minimum orientation of the liquid crystal display device is consistent with the four orientations that bisect the absorption axis and the transmission axis of the polarizer.

The form of the liquid crystal cell is not particularly limited, and examples include a form having a liquid crystal sandwiched between a thin film transistor array substrate and a color filter substrate. In addition, the form of the above-mentioned polarizer is not particularly limited, and examples include a form in which a polarizer and a support film are included in the order from the liquid crystal cell side, and a form in which the support film and the polarizer are included in the order from the liquid crystal cell side. The mode of inclusion is the mode of including the first support film, the polarizing element, and the second support film in this order from the liquid crystal cell side. As the above-mentioned support film, the same material as the transparent substrate of the anisotropic scattering film can be used. In addition, the above-mentioned polarizing plate is usually arranged on both the observation surface side and the rear surface side of the liquid crystal cell, but may be arranged only on the observation surface side or only on the rear surface side. The above polarizing plate preferably further includes a retardation film. Thereby, viewing angle dependence such as chromaticity of the liquid crystal display device can also be improved.

The display mode of the liquid crystal display device is not particularly limited, but for example, VA (Vertical Alignment: Vertical Alignment) mode, TN (Twisted Nematic: Twisted Nematic) mode, and IPS (In-Plane Switching: In-plane switching) mode are preferable. , or OCB (Optically Compensated Birefringence: Optically Compensated Birefringence) mode.

The VA mode is a method in which liquid crystal molecules are aligned approximately perpendicular to the substrate surface when no voltage is applied, and display is performed by inclining the liquid crystal molecules by applying a voltage. Examples of the VA mode include the MVA (Multi-domain Vertical Alignment: Multi-domain Vertical Alignment) mode in which a liquid crystal cell is divided into multiple domains by providing a protrusion structure and/or slits on the substrate. In a VA-mode liquid crystal display device, the liquid crystal preferably has negative dielectric constant anisotropy.

The so-called TN mode is a method in which, when no voltage is applied, the long axis of the liquid crystal molecules is approximately parallel to the substrate surface, and between a pair of substrates, they are continuously twisted at a predetermined angle (twist angle). Display is performed by rearranging the major axes parallel to the direction of the electric field. The TN mode includes not only a normal TN mode with a twist angle of 90 degrees, but also an STN mode with a twist angle of 180 degrees or more. In addition, in a TN mode liquid crystal display device, the liquid crystal preferably has positive dielectric constant anisotropy.

The so-called IPS mode is a method in which liquid crystal is rotated in the plane of a substrate by a transverse electric field applied to a pair of comb-shaped electrodes provided on one substrate to perform display. In the case of liquid crystal molecules having negative dielectric constant anisotropy, when no voltage is applied, the long axis of the liquid crystal molecules is arranged in a direction approximately perpendicular to the direction of the comb teeth of the comb-shaped electrode, and by applying a voltage, the long axis of the liquid crystal molecules is arranged in a direction approximately parallel to the direction of the comb teeth of the comb electrode. Rotate in the direction of the comb-tooth direction of the shaped electrode. In addition, when the liquid crystal molecules have positive dielectric constant anisotropy, when no voltage is applied, the long axes of the liquid crystal molecules are arranged in a direction approximately parallel to the comb-tooth direction of the comb-shaped electrodes, and are arranged approximately vertically by applying a voltage. Rotate in the direction of the comb-tooth direction of the comb-shaped electrode. In addition, when no voltage is applied, the long axes of the liquid crystal molecules are arranged approximately parallel to the substrate surface and the polarization axis of one polarizer regardless of whether the dielectric anisotropy of the liquid crystal molecules is positive or negative.

The so-called OCB mode is a method in which an optically complementary alignment structure (bend alignment) is provided in the thickness direction of the liquid crystal, and at the same time, three-dimensional optical compensation is performed using a retardation film.

According to the display device of the present invention, it is possible to improve the display quality in at least a specific direction without changing the design of the basic structure of the display device, without being limited by the white display state or the black display state, and without impairing the display quality in other directions. The viewing angle dependence of the ratio.

Examples are suggested below, and the present invention will be described in more detail, but the present invention is not limited only to these Examples.

1. Fabrication of liquid crystal display devices of Examples 1 to 8 and Comparative Examples 1 and 2

<Example 1>

(Fabrication of the first anisotropic scattering film)

First, a polyethylene terephthalate (PET) film (trade name: COSMOSHINE (registered trademark), model: A4300, manufactured by Toyobo Co. ) after the liquid resin was ejected from the edge portion, the liquid resin was solidified to form a partition wall with a height of 0.2 mm. Then, after dropping the photopolymerizable composition of the following composition in the area|region surrounded by a partition, it covered with another PET film.

"Composition of Photopolymerizable Composition"

2-(perfluorooctyl)-ethyl acrylate 50 parts by weight

1,9-nonanediol diacrylate 50 parts by weight

2-Hydroxy-2-methyl-1-phenylpropan-1-one 4 parts by weight

Afterwards, for the liquid film with a thickness of 0.2mm sandwiched between the upper and lower sides by the PET film, the UV spot light source (trade name: L2859-01, manufactured by Hamamatsu Photonics Co., Ltd.) for epi-radiation irradiation unit was tilted at an angle of 30 degrees from the vertical direction. The first anisotropic scattering film was obtained by irradiating ultraviolet rays with an irradiation intensity of 30 mW/cm ² for one minute. In the first anisotropic scattering film, when the cross-section was observed under a microscope, it was confirmed that there were rod-shaped solidified regions 20 extending at an inclination of 30 degrees with respect to the normal direction of the film surface as shown in FIG. 2A .

(Measurement of the scattering properties of the first anisotropic scattering film)

Fig. 6 is a schematic perspective view showing a method of measuring the anisotropic scattering characteristic of the first anisotropic scattering film.

According to the method shown in FIG. 6, by rotating the test piece 10a with a predetermined direction as the rotation axis, not only the amount of linearly transmitted light when the optical axis coincides with the normal direction of the test surface (when the incident angle is 0 degrees) can be measured, It is also possible to measure the amount of straight-line transmitted light when the optical axis does not coincide with the normal direction of the test surface (when the incident angle is other than 0 degrees). Specifically, first, using a goniophotometer (trade name: automatic variable goniophotometer GP-5, manufactured by Murakami Color Technology Laboratory Co., Ltd.), as shown in FIG. The position of the light was fixed to the light receiving unit 30, and the first anisotropic scattering film was mounted on a sample holder (not shown) between the light source and the light receiving unit 30 to form a test piece 10a. Thereafter, as shown in FIG. 6, the first anisotropic scattering film 10a is rotated (hereinafter also referred to as "short-side axis rotation") with the short-side direction of the first anisotropic scattering film 10a as the rotation axis (L). .), while measuring the amount of light transmitted through a line corresponding to each incident angle. Thereafter, the first anisotropic scattering film 10a is rotated (hereinafter also referred to as "longitudinal axis rotation") with the longitudinal direction of the first anisotropic scattering film 10a as the axis of rotation (M), and the corresponding The amount of light transmitted through a straight line at each incident angle.

The direction of the short axis of the first anisotropic scattering film 10 a coincides with the direction perpendicular to the direction in which the rod-shaped solidified regions 20 extend, and the direction of the long axis coincides with the direction of the direction in which the rod-shaped solidified regions 20 extend. That is, by rotating the short axis of the first anisotropic scattering film 10a, the anisotropic scattering characteristic in the direction of extension of the rod-shaped solidified region 20 is measured, and by rotating the long axis of the first anisotropic scattering film 10a, the vertical Anisotropic scattering properties in the orientation of the extension orientation of the rod-shaped solidified region 20 .

Fig. 7 is a graph showing the relationship between the incident angle and the amount of linearly transmitted light when the first anisotropic scattering film is rotated about the above-mentioned two rotation axes. The positive and negative of the incident angle indicate that the direction of rotation of the first anisotropic scattering film is opposite.

As can be seen from FIG. 7 , in the extension direction of the rod-shaped solidified region 20 , it is in the shape of a deep valley including hills at an incident angle of 30 degrees. In addition, in the azimuth perpendicular to the extension azimuth of the rod-shaped solidified region 20 , an incident angle of 0 degrees is the deepest valley shape. Therefore, it can be seen that the first anisotropic scattering film 10 a has a scattering central axis in a direction that coincides with the extending direction of the rod-shaped hardened regions 20 , that is, the polar angle of the scattering central axis is 30 degrees.

8 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 1 of the present invention. The relationship between the lamination of each film and the axial direction is shown in Figure 8 and Table 1.

[Table 1]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 90 degrees 1st polarizer 13a-observation side (absorption axis a) 0～180 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 1st retardation film 12a (slow axis s) 0～180 degrees 1st polarizer 13a-back side (absorption axis a) 90～270 degrees

(Fabrication of VA Mode Liquid Crystal Display Device 15a)

First, a VA-mode liquid crystal cell 11a is trial-manufactured, and the relationship between the birefringence Δn of the liquid crystal material and the cell thickness d is adjusted to Δnd=300nm. When a voltage is applied, the liquid crystal is divided along four directions such as azimuth angles of 45, 135, 225, and 315 degrees. The tilted orientation of the molecule. Afterwards, the first retardation film 12a is pasted on the backlight side of the VA mode liquid crystal unit 11a, and the support film on the VA mode liquid crystal unit 11a side is the first polarizing plate 13a of TAC (triacetate fiber) film. The backlight side of the first retardation film 12a and the viewing surface side of the VA mode liquid crystal cell 11a constitute a VA mode liquid crystal display device 15a.

The retardation of the first retardation film 12a is Re=3nm, Rth=250nm. When the two main refractive indices in the plane of the three main refractive indices of the refractive index ellipsoid are defined as nx, ny (nx≥ny), one main refractive index in the normal direction is defined as nz, and the phase difference film is defined as When the thickness is defined as d, the above-mentioned Re is represented by the following formula (1).

Re＝(nx-ny)×d (1)

When nx, ny, nz, and d are defined as above, Rth is represented by the following formula (2).

Rth＝(nx-nz)×d (2)

The calculation methods of Re and Rth are the same in the following Examples and Comparative Examples. In addition, the performance of the polarizing element constituting the first polarizing plate 13a is that the parallel transmittance is 36.25%, the orthogonal transmittance is 0.005%, and the polarization degree is 99.99%.

(Measurement of Optical Characteristics of VA Mode Liquid Crystal Display Device 15a)

Using a viewing angle measuring device (trade name: EZContrast160R, manufactured by ELDIM), the azimuth angle dependence of the contrast ratio of the VA-mode liquid crystal display device 15a produced in Example 1 in the direction of polar angle Θ = 45 degrees was measured. The result is shown in Figure 16. As can be seen from FIG. 16, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of the polar angle Θ=45 degrees is the maximum azimuth (maximum azimuth) is the azimuth angle Φ=0, 90, 180, 270 degrees and other four directions. . The contrast ratio of the VA mode liquid crystal display device 15a in the direction of the polar angle Θ=45 degrees is the minimum azimuth (minimum azimuth) in four directions such as azimuth angles Φ=45, 135, 225, and 315 degrees.

(Fabrication of VA Mode Liquid Crystal Display Device 100a)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15a so that the VA mode liquid crystal display device 15a is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=90 degrees. The axial directions _S1 of the scattering central axis of the anisotropic scattering film 10a are approximately the same, constituting the VA mode liquid crystal display device 100a.

<Example 2>

FIG. 9 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 2 of the present invention. The relationship between the lamination of each film and the axial direction is shown in Figure 9 and Table 2.

[Table 2]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 90 degrees Polarizer 3a-observation side (absorption axis a) 0～180 degrees Second retardation film 12b (slow axis s) 90～270 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 3rd retardation film 12c (slow axis s) 0～180 degrees Polarizing element 3a-back side (absorption axis a) 90～270 degrees

(Fabrication of VA Mode Liquid Crystal Display Device 15a)

First, the support film on the side of the liquid crystal cell 11a is attached to the viewing surface side of the VA mode liquid crystal cell 11a made in Example 1, and the second polarizer 13b of the second retardation film 12b is attached to the side of the liquid crystal cell 11a. The support film is the third polarizer 13c of the third retardation film 12c, which is attached to the backlight side to form a VA mode liquid crystal display device 15a.

The retardation of the second retardation film 12b is Re=140nm, Rth=138nm. The retardation of the third retardation film 12c is Re=2nm, Rth=190nm. The performance of the polarizing element 3a is the same as that of the polarizing element of the first embodiment.

(Measurement of Optical Characteristics of VA Mode Liquid Crystal Display Device 15a)

Using a viewing angle measuring device (trade name: EZContrast160R, manufactured by ELDIM), the azimuthal dependence of the contrast ratio of the VA mode liquid crystal display device 15a produced in Example 2 in the direction of polar angle Θ = 45 degrees was measured, and the results were compared with those in the implementation. As in Example 1, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of polar angle Θ = 45 degrees is the maximum azimuth (maximum azimuth) in four directions such as azimuth angles Φ = 0, 90, 180, and 270 degrees. In addition, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of the polar angle Θ = 45 degrees is the minimum azimuth (minimum azimuth) in four directions such as azimuth angles Φ = 45, 135, 225, and 315 degrees.

(Fabrication of VA Mode Liquid Crystal Display Device 100a)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15a so that the VA mode liquid crystal display device 15a is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=90 degrees. The axial directions _S1 of the scattering central axis of the anisotropic scattering film 10a are approximately the same, constituting the VA mode liquid crystal display device 100a.

<Example 3>

FIG. 10 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 3 of the present invention. Figure 10 and Table 3 show the relationship between the lamination of each film and the axial direction.

[table 3]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 90 degrees 1st polarizer 13a-observation side (absorption axis a) 0～180 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 4th retardation film 12d (slow axis s) 0～180 degrees 1st polarizer 13a-back side (absorption axis a) 90～270 degrees

(Fabrication of VA Mode Liquid Crystal Display Device 15a)

First, the 4th retardation film 12d is pasted on the backlight side of the VA mode liquid crystal cell 11a made in embodiment 1, and the support film on the liquid crystal cell 11a side is the first polarizer 13a made of a TAC film. A VA-mode liquid crystal display device 15a is formed on the backlight side of the fourth retardation film 12d and the viewing surface side of the liquid crystal cell 11a.

The retardation of the fourth retardation film 12d is Re=50nm, Rth=220nm. The performance of the first polarizer 13a is the same as that of the first embodiment.

(Measurement of Optical Characteristics of VA Mode Liquid Crystal Display Device 15a)

Using a viewing angle measuring device (trade name: EZContrast160R, manufactured by ELDIM), the azimuth dependence of the contrast ratio of the VA mode liquid crystal display device 15a produced in Example 3 in the direction of the polar angle Θ = 45 degrees was measured, and the results were compared with those in the implementation. As in Example 1, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of polar angle Θ = 45 degrees is the maximum azimuth (maximum azimuth) in four directions such as azimuth angles Φ = 0, 90, 180, and 270 degrees. In addition, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of the polar angle Θ = 45 degrees is the minimum azimuth (minimum azimuth) in four directions such as azimuth angles Φ = 45, 135, 225, and 315 degrees.

(Fabrication of VA Mode Liquid Crystal Display Device 100a)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15a so that the VA mode liquid crystal display device 15a is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=90 degrees. The axial directions _S1 of the scattering central axis of the anisotropic scattering film 10a are approximately the same, constituting the VA mode liquid crystal display device 100a.

<Example 4>

FIG. 11 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 4 of the present invention. Figure 11 and Table 4 show the relationship between the lamination of each film and the axial direction.

[Table 4]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 90 degrees Polarizer 3a-observation side (absorption axis a) 0～180 degrees Fifth retardation film 12e (slow axis s) 90～270 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 6th retardation film 12f (slow axis s) 0～180 degrees Polarizing element 3a-back side (absorption axis a) 90～270 degrees

(Fabrication of VA Mode Liquid Crystal Display Device 15a)

First, the support film on the side of the liquid crystal cell 11a is bonded to the viewing surface side of the VA-mode liquid crystal cell 11a made in Example 1, and the fifth polarizer 13e of the fifth retardation film 12e is bonded to the side of the liquid crystal cell 11a. The supporting film is the sixth polarizing plate 13f of the sixth retardation film 12f, which is attached to the backlight side to form the VA mode liquid crystal display device 15a.

The retardation of the fifth and sixth retardation films 12e and 12f are both Re=60nm and Rth=90nm. The performance of the polarizing element 3a is the same as that of the polarizing element of the first embodiment.

(Measurement of Optical Characteristics of VA Mode Liquid Crystal Display Device 15a)

Using a viewing angle measuring device (trade name: EZContrast160R, manufactured by ELDIM), the azimuth dependence of the contrast ratio of the VA mode liquid crystal display device 15a produced in Example 4 in the direction of polar angle Θ = 45 degrees was measured, and the results were compared with those in the implementation. As in Example 1, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of polar angle Θ = 45 degrees is the maximum azimuth (maximum azimuth) in four directions such as azimuth angles Φ = 0, 90, 180, and 270 degrees. In addition, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of the polar angle Θ = 45 degrees is the minimum azimuth (minimum azimuth) in four directions such as azimuth angles Φ = 45, 135, 225, and 315 degrees.

(Fabrication of VA Mode Liquid Crystal Display Device 100a)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15a so that the VA mode liquid crystal display device 15a is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=90 degrees. The axial directions _S1 of the scattering central axis of the anisotropic scattering film 10a are approximately the same, constituting the VA mode liquid crystal display device 100a.

<Example 5>

FIG. 12 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 5 of the present invention. Figure 12 and Table 5 show the relationship between the lamination of each film and the axial direction.

[table 5]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 90 degrees Polarizer 3a-observation side (absorption axis a) 0～180 degrees 7th retardation film 12g (slow axis s) 90～270 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees Eighth retardation film 12h (slow axis s) 0～180 degrees Polarizing element 3a-back side (absorption axis a) 90～270 degrees

(Fabrication of VA Mode Liquid Crystal Display Device 15a)

First, the support film on the side of the liquid crystal cell 11a is bonded to the viewing surface side of the VA-mode liquid crystal cell 11a made in Example 1, and the support film on the side of the liquid crystal cell 11a is made to be the seventh polarizer 13g of the seventh retardation film 12g. The support film is the eighth polarizer 13h of the eighth retardation film 12h, which is pasted on the backlight side to form the VA mode liquid crystal display device 15a.

The retardation of the seventh retardation film 12g is Re=90nm, Rth=100nm, and the retardation of the eighth retardation film 12h is Re=3nm, Rth=100nm. The performance of the polarizing element 3a is the same as that of the polarizing element of the first embodiment.

(Measurement of Optical Characteristics of VA Mode Liquid Crystal Display Device 15a)

Using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM), the azimuth dependence of the contrast ratio of the VA mode liquid crystal display device 15a produced in Example 5 in the direction of polar angle Θ=45 degrees was measured, and the results were compared with those in the implementation. As in Example 1, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of polar angle Θ = 45 degrees is the maximum azimuth (maximum azimuth) in four directions such as azimuth angles Φ = 0, 90, 180, and 270 degrees. In addition, the contrast ratio of the VA mode liquid crystal display device 15a in the direction of the polar angle Θ = 45 degrees is the minimum azimuth (minimum azimuth) in four directions such as azimuth angles Φ = 45, 135, 225, and 315 degrees.

(Fabrication of VA Mode Liquid Crystal Display Device 100a)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15a so that the VA mode liquid crystal display device 15a is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=90 degrees. The axial directions _S1 of the scattering central axis of the anisotropic scattering film 10a are approximately the same, constituting the VA mode liquid crystal display device 100a.

<Example 6>

FIG. 13 is a schematic perspective view showing the configuration of a TN-mode liquid crystal display device 100b according to Embodiment 6 of the present invention. Figure 13 and Table 6 show the relationship between the lamination of each film and the axial direction.

[Table 6]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 225 degrees Polarizer 3b-observation side (absorption axis a) 45～225 degrees WV film 4-observation surface side (orientation control direction of liquid crystal b) 45 degree TN mode liquid crystal cell 11b (alignment control direction d of liquid crystal) 45 degrees (observation side), 315 degrees (rear side) WV film 4-back side (alignment control direction b of liquid crystal) 315 degrees Polarizing element 3b-back side (absorption axis a) 90～270 degrees

(Fabrication of TN Mode Liquid Crystal Display Device 15b)

At first, the TN mode liquid crystal cell 11b is trial-manufactured, the relationship between the birefringence Δn of the liquid crystal material and the cell thickness d is adjusted to Δnd=350nm, and the polarizer (trade name: attached) with a wide view angle (wide view) (WV) film 4 is made The polarizer NWF-KD·EG of the viewing angle compensation film, manufactured by Nitto Denko Co., Ltd.) 13i is pasted on both outer sides thereof to form a TN mode liquid crystal display device 15b.

The polarizing element 3b is different from the polarizing element 3a. In addition, the performance of the polarizer 13i is that the parallel transmittance is 36.10%, the orthogonal transmittance is 0.005%, and the polarization degree is 99.99%.

(Measurement of Optical Characteristics of TN Mode Liquid Crystal Display Device 15b)

Using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM), the azimuth angle dependence of the contrast ratio of the TN mode liquid crystal display device 15b in the direction of polar angle Θ = 45 degrees was measured. The results are shown in Figure 17. As can be seen from FIG. 17, the contrast ratio of the TN mode liquid crystal display device 15b in the direction of the polar angle Θ=45 degrees is the maximum orientation (maximum orientation) is the four orientations such as the azimuth angle Φ=45, 135, 225, and 315 degrees. . The contrast ratio of the TN mode liquid crystal display device 15b in the direction of the polar angle Θ = 45 degrees is the minimum azimuth (minimum azimuth) in four directions such as the azimuth angle Φ = 0, 90, 180, and 270 degrees.

(Fabrication of TN Mode Liquid Crystal Display Device 100b)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15b so that the TN mode liquid crystal display device 15b is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=225 degrees. The axis orientation _S1 of the scattering central axis of the anisotropic scattering film 10a is approximately the same, constituting the TN mode liquid crystal display device 100b.

<Example 7>

FIG. 14 is a schematic perspective view showing the configuration of an IPS mode liquid crystal display device 100c according to Embodiment 7 of the present invention. Figure 14 and Table 7 show the relationship between the lamination of each film and the axial direction.

[Table 7]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 90 degrees 9th polarizer 13j-observation side (absorption axis a) 0～180 degrees IPS mode liquid crystal cell 11c (alignment control direction d of liquid crystal) 90～270 degrees Ninth retardation film 12j (slow axis s) 90～270 degrees 9th polarizer 13j-back side (absorption axis a) 90～270 degrees

(Manufacturing of IPS mode liquid crystal display device 15c)

First, the polarizers attached to the observation side and the backlight side of a commercially available IPS mode liquid crystal TV (trade name: TH-26LX50, manufactured by Panasonic Corporation) were peeled off to prepare the IPS mode liquid crystal cell 11c. Afterwards, the 9th retardation film 12j is pasted on the backlight side of the liquid crystal cell 11c, and the 9th polarizer 13j is pasted on the backlight side of the 9th retardation film 12j and the observation surface of the liquid crystal cell 11c On one side, an IPS mode liquid crystal display device 15c is formed.

The retardation of the ninth retardation film 12j is Re=140nm, Rth=45nm. In addition, the performance of the ninth polarizer 13j is that the parallel transmittance is 35.95%, the orthogonal transmittance is 0.004%, and the degree of polarization is 99.99%.

(Measurement of Optical Characteristics of IPS Mode Liquid Crystal Display Device 15c)

Using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM), the azimuth angle dependence of the contrast ratio of the IPS mode liquid crystal display device 15c in the direction of the polar angle Θ = 45 degrees was measured. The results are shown in Figure 18. It can be seen from FIG. 18 that the contrast ratio of the IPS mode liquid crystal display device 15c in the direction of the polar angle Θ=45 degrees is the maximum orientation (maximum orientation) is the azimuth angle Φ=0, 90, 180, 270 degrees and other four orientations. . The contrast ratio of the IPS mode liquid crystal display device 15c in the direction of the polar angle Θ=45 degrees is the minimum azimuth (minimum azimuth) in four directions such as azimuth angles Φ=45, 135, 225, and 315 degrees.

(Manufacturing of IPS mode liquid crystal display device 100c)

Next, the first anisotropic scattering film 10a is bonded to the viewing surface side of the liquid crystal display device 15c so that the IPS mode liquid crystal display device 15c is aligned with the first each in the orientation (maximum orientation) of the azimuth angle Φ=90 degrees. The axis orientation _S1 of the scattering central axis of the anisotropic scattering film 10a is approximately the same, constituting the IPS mode liquid crystal display device 100c.

<Embodiment 8>

(Manufacturing of OCB mode liquid crystal display devices and measurement of optical properties)

A commercially available OCB-mode liquid crystal TV (trade name: VT23XD1, manufactured by Nanao Co., Ltd.) was peeled off from a part of the polarizer on the backlight side and bonded to the observation side to form an OCB-mode liquid crystal display device. The performance of the partially peeled polarizer is that the parallel transmittance is 36.30%, the orthogonal transmittance is 0.005%, and the polarization degree is 99.99%. Thereafter, using a viewing angle measuring device (trade name: EZContrast 160R, manufactured by ELDIM Corporation), the azimuth angle dependence of the contrast ratio of the OCB mode liquid crystal display device in the direction of polar angle Θ = 45 degrees was measured. The result is shown in Figure 19. As can be seen from FIG. 19, the contrast ratio of the OCB mode liquid crystal display device 15c in the direction of the polar angle Θ=45 degrees is the maximum orientation (maximum orientation) is the four orientations such as the azimuth angle Φ=45, 135, 225, and 315 degrees. . In addition, the contrast ratio of the OCB mode liquid crystal display device 15c in the direction of the polar angle Θ = 45 degrees is the minimum azimuth (minimum azimuth) in four directions such as the azimuth angle Φ = 0, 90, 180, and 270 degrees.

(Manufacturing of OCB mode liquid crystal display device)

Then, the first anisotropic scattering film 10a is pasted on the viewing side surface of the OCB mode liquid crystal display device, so that the orientation (maximum orientation) of the OCB mode liquid crystal display device is at the orientation angle (maximum orientation) of 45 degrees and the first orientation. The axial directions _S1 of the scattering central axis of the anisotropic scattering film 10a are approximately the same, constituting an OCB mode liquid crystal display device.

<Comparative example 1>

(Production of isotropic scattering film)

On one side of a PET film (trade name: COSMOSHINE (registered trademark), model: A4300, manufactured by Toyobo Co., Ltd.) with a thickness of 75 μm, a UV coating of the following formulation was coated with a wire bar. Thereafter, the film coated with the UV coating was dried and UV irradiated (cured) to obtain an isotropic scattering film having a coating layer having a film thickness of about 3 micrometers.

《UV paint》

UV curable resin (trade name: BEAMSET (registered trademark) 575CB, 100% non-volatile content, manufactured by Arakawa Chemical Industry Co., Ltd.) 98 parts by weight

Polystyrene microparticles (trade name: SX350H, average particle diameter: 3.5 micrometers, Soken Chemical Co., Ltd. product) 12 parts by weight

MIBK (methyl isobutyl ketone) 100 parts by weight

(Measurement of Scattering Properties of Isotropic Scattering Films)

The measurement method is the same as that of the first anisotropic scattering film. The scattering properties of the isotropic scattering film are shown in FIG. 15 . In the case of an isotropic scattering film, as shown in FIG. 15 , the curve showing the incident angle dependence of the scattering characteristic is in a convex shape centered on the incident angle of 0°. This is due to the fact that the greater the angle of incidence, the greater the distance through the film. In addition, the positive and negative angles of incidence indicate that the direction of rotation is opposite.

(Manufacturing of liquid crystal display devices)

On the viewing side of the VA-mode liquid crystal display device 15a trial-produced in Example 1, a turbidity meter (trade name: NDH-2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.)) was bonded to an isotropic glass with a turbidity of 30%. Homotropic scattering film constitutes a VA mode liquid crystal display device. In addition, it is the same as that of Example 1 except that an isotropic scattering film is used instead of the first anisotropic scattering film.

<Comparative example 2>

(Manufacturing of liquid crystal display devices)

On one side of the observation surface of the VA mode liquid crystal display device 15a trial-produced in embodiment 3, a viewing angle control film (product name: LUMISTY (registered trademark), model: MFY-1060, manufactured by Sumitomo Chemical Co., Ltd.) is attached to form a VA mode liquid crystal display. device. LUMISTY (registered trademark) is a thin film showing anisotropic scattering properties in a specific direction. In this comparative example, LUMISTY (registered trademark), which scatters light incident at a polar angle Θ = 10 to 60 degrees in a certain direction (hereinafter referred to as "scattering direction"), was bonded to a VA mode liquid crystal display device. 15a so that the direction of scattering substantially coincides with the azimuth (maximum azimuth) of the azimuth angle Φ=90 degrees of the VA mode liquid crystal display device 15a. Therefore, the configuration of this comparative example is the same as that of Example 3 except that LUMISTY (registered trademark) is used instead of the first anisotropic scattering film.

2. Measurement of Optical Properties of the Liquid Crystal Display Devices of Examples 1 to 8 and Comparative Examples 1 and 2

Using a viewing angle measuring device (trade name: EZContrast160R, manufactured by ELDIM Corporation), in the liquid crystal display devices of Examples 1 to 8 and Comparative Examples 1 and 2, the black display time (gray value: 0) when performing 256 gray scale display was measured. ), halftone display (grayscale value: 128), and white display (grayscale value: 225) viewing angle dependence of brightness and chromaticity. The viewing angle is represented by the polar angle Θ and the azimuth angle Φ.

<Evaluation of viewing angle-dependent improvement of contrast ratio>

In each liquid crystal display device, the polar angle dependence of the contrast ratio of the liquid crystal display device was evaluated in an azimuth (maximum azimuth) in which the contrast ratio in the direction of polar angle Θ = 45 degrees was maximized. That is, in the liquid crystal display devices of VA mode and IPS mode, the azimuth angles Φ=0, 90, 180, and 270 degrees were evaluated, and in the liquid crystal display devices of TN mode and OCB mode, the azimuth angles Φ=45, 135, and 225 degrees were evaluated. Polar angle dependence of the contrast ratio in 4 directions such as , 315 degrees, etc. In addition, the contrast ratio was obtained by the following formula (3) from the measured luminance at the time of black display (gradation value: 0) and the time of white display (gradation value: 255).

(Contrast Ratio) = (White Display Brightness)/(Black Display Brightness) (3)

The polar angle dependence of the contrast ratio of the liquid crystal display devices and liquid crystal display devices of Examples 1 to 8 and Comparative Examples 1 and 2 in the maximum orientation is shown in FIGS. 20A to 29A and 20B to 29B. The solid line in each figure shows the polar-angle dependence of the contrast ratio of the liquid crystal display device, and the dotted line shows the polar-angle dependence of the contrast ratio of the liquid crystal display device.

FIGS. 20A to 27A show the polar angle dependence of the contrast ratio on two maximum azimuths of the axial orientation approximately parallel to the scattering central axis of the first anisotropic scattering film 10a, and FIGS. Polar angle dependence of the contrast ratio on the 2 azimuth.

In the VA-mode liquid crystal display devices of Examples 1 to 5 of the present invention, as can be seen from FIGS. 20A to 24A , in the maximum orientation (orientation with an azimuth angle Φ=90 degrees) approximately coincident with the axial orientation of the scattering central axis, In the vicinity of the axial direction of the scattering central axis (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the viewing angle dependence of the contrast ratio is improved. In addition, under the azimuth opposite to the maximum azimuth (the azimuth angle Φ=270 degrees) and two directions perpendicular to the maximum azimuth (the azimuth angles Φ=0, 180 degrees), from FIGS. 20A to 24A As can be seen from 20B to 24B, there is no influence such as a decrease in the contrast ratio.

However, in the VA mode liquid crystal display device of Comparative Example 1, as shown in FIGS. 28A and 28B , the contrast ratio was not improved in any direction. In addition, in the VA mode liquid crystal display device of Comparative Example 2, as shown in FIG. 29A , although the viewing angle is improved in the maximum azimuth (the azimuth angle Φ = 90 degrees) substantially coincident with the scattering direction, the viewing angle is improved. However, as shown in FIG. 29B As shown, the contrast ratio is very low in a wide range in the two azimuths approximately perpendicular to the scattering direction (the azimuth angle Φ=0 and the azimuth of 180 degrees), and in the frontal direction (the direction of the polar angle Θ=0 degrees) The resulting maximum contrast ratio is also very low.

In addition, in the TN-mode liquid crystal display device according to Example 6 of the present invention, it can be seen from FIG. 25A that in the maximum azimuth (orientation with azimuth angle Φ=225 degrees) approximately coincident with the axial azimuth of the scattering central axis, the scattering central axis In the vicinity of the axial direction (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the effect of improving the viewing angle dependence of the contrast ratio is obtained. In addition, under the orientation opposite to the maximum orientation (azimuth angle Φ = 45 degree orientation) and two orientations perpendicular to the maximum orientation (azimuth angle Φ = 135, 315 degree orientation), from Figures 25A and 25B It can be seen that there is no influence such as a decrease in the ratio.

In addition, in the IPS mode liquid crystal display device according to Example 7 of the present invention, it can be seen from FIG. 26A that at the maximum orientation (the orientation at which the azimuth angle Φ=90 degrees) approximately coincides with the axial orientation of the scattering central axis, the scattering central axis In the vicinity of the axial direction (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the effect of improving the viewing angle dependence of the contrast ratio is obtained. In addition, under the orientation opposite to the maximum orientation (azimuth angle Φ = 270 degree orientation) and 2 orientations perpendicular to the maximum orientation (azimuth angle Φ = 0, 180 degree orientation), from Figs. 26A and 26B It can be seen that there is no influence such as a decrease in the ratio.

In addition, in the OCB mode liquid crystal display device of Example 8 of the present invention, it can be seen from FIG. 27A that in the maximum azimuth (the azimuth angle Φ = 45 degrees) approximately coincident with the axial direction of the scattering central axis, the scattering central axis In the vicinity of the axial direction (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the effect of improving the viewing angle dependence of the contrast ratio is obtained. In addition, under the orientation opposite to the maximum orientation (azimuth angle Φ = 225 degree orientation) and two orientations perpendicular to the maximum orientation (azimuth angle Φ = 135, 315 degree orientation), from Figures 27A and 27B It can be seen that there is no influence such as a decrease in the ratio.

This is explained below as follows. According to the liquid crystal display devices of Embodiments 1 to 8 of the present invention, since the first anisotropic scattering film is bonded on the viewing surface side of the liquid crystal display device, the axis orientation of the scattering central axis is consistent with the observation from the liquid crystal display device. The contrast ratio in the direction after the surface normal direction is inclined by 45 degrees is approximately the same in the maximum direction (maximum direction), and the incident light (white brightness) in the axial direction approximately parallel to the scattering central axis can be made along the scattering central axis Scattering (diffusion) in all directions centered on the center is averaged, so that the viewing angle dependence of the contrast ratio can be improved in the maximum direction that at least approximately coincides with the axis direction of the scattering center axis. In addition, the first anisotropic scattering film exhibits the scattering characteristics shown in FIG. 7, and since light incident from a direction other than the direction approximately parallel to the axial direction of the scattering center axis is only weakly scattered, it is possible to suppress light incident from this direction. Scattering of incident light degrades display quality in directions such as directions with a high contrast ratio. That is, the first anisotropic scattering film can improve the width around the scattering center axis without affecting the contrast ratio in other directions compared with the conventional anisotropic scattering film showing anisotropic scattering characteristics only in a specific direction. The viewing angle dependence of the azimuthal contrast ratio.

In contrast, according to the liquid crystal display device of Comparative Example 1, since the isotropic scattering film used instead of the first anisotropic scattering film exhibits the scattering characteristics shown in FIG. Averaging, so the viewing angle dependence of the contrast ratio cannot be improved in either orientation. In addition, according to the liquid crystal display device of Comparative Example 2, since LUMISTY (registered trademark) used in place of the first anisotropic scattering film shows anisotropic scattering characteristics only in a specific direction, it does not show anisotropic scattering characteristics. In the azimuth, incident light in a direction with a low contrast ratio is strongly scattered, and as a result, the maximum contrast ratio obtained in a frontal direction or the like is lowered due to scattering of incident light in that direction.

<Evaluation of improvement in gamma curve deviation>

Find the gamma curve on the front direction (the direction of polar angle Θ=0 degree) and the oblique direction (polar angle Θ=40 degree, the orientation is that the contrast of each liquid crystal display device on the direction of polar angle Θ=40 degree is The γ curve in the direction of the maximum azimuth) normalizes the luminance in each grayscale display, and makes the white display luminance 1, and calculates the normalized luminance in the front direction and each oblique direction when the halftone is displayed (grayscale value: 128) The difference (bias) of the normalized luminance of . Table 8 shows the ratio of improvement effects from liquid crystal display devices. That is, the larger the numerical value described in the table, the larger the effect of improvement.

[Table 8]

Φ＝0 degree Φ＝90 degrees Φ＝180 degrees Φ＝270 degrees Example 1 19 48 twenty one twenty three Example 2 20 52 19 twenty one Example 3 18 49 20 18 Example 4 19 50 twenty one twenty three Example 5 twenty two 55 twenty two 19 Comparative example 1 11 12 12 15 Comparative example 2 15 38 10 14

It can be seen from Table 8 that in the liquid crystal display devices of Examples 1 to 5 of the present invention, in the maximum orientation (the orientation of the azimuth angle Φ = 90 degrees) approximately consistent with the axial orientation of the scattering central axis, the γ curve deviation improvement effect big. In addition, in the three maximum azimuths (azimuth angles Φ=0, 180, and 270 degrees) other than the maximum azimuth, the effect of improving the deviation of the γ curve can also be obtained. However, in the liquid crystal display device of Comparative Example 1, the effect of improving deviation of the γ curve was small in any maximum orientation. In addition, in the liquid crystal display device of Comparative Example 2, although the effect of improving the deviation of the γ curve is large in the maximum azimuth (the azimuth angle Φ = 90 degrees) that substantially coincides with the scattering direction, the viewing angle of the above-mentioned contrast ratio As shown in the evaluation results of dependency improvement, the maximum contrast ratio decreased significantly.

This is explained below as follows. The γ curve of a VA mode liquid crystal display device is usually optimally designed in the direction in which the contrast ratio is the largest, and its viewing angle dependence shows the same tendency as that of the contrast ratio. According to the liquid crystal display devices of Examples 1 to 5 of the present invention and Comparative Example 2, since the first anisotropic scattering film and LUMISTY (registered trademark) show anisotropic scattering characteristics in at least one direction, when each film is pasted When combined on the side of the viewing surface of the VA mode liquid crystal display device, by making the directions representing the anisotropic scattering characteristics of each film roughly consistent with the maximum direction of the VA mode liquid crystal display device, in this maximum direction, it can be greatly improved. Improve viewing angle dependence of gamma curve. According to the liquid crystal display devices of Examples 1 to 5 of the present invention, since the first anisotropic scattering film exhibits anisotropic scattering characteristics in all directions, even in the directions approximately corresponding to the directions showing the anisotropic scattering characteristics of each film, Also in the three maximum orientations other than the maximum orientation, the viewing angle dependence of the γ curve can be improved. In contrast, according to the liquid crystal display device of Comparative Example 1, since the isotropic scattering film used instead of the first anisotropic scattering film did not show anisotropic scattering characteristics, it was not possible to scatter only incident light in a specific direction in all directions and Averaging is performed, and as a result, viewing angle dependence of the γ curve cannot be improved.

3. Fabrication of liquid crystal display devices of Examples 9 to 17 and Comparative Example 3

<Example 9>

30 is a schematic perspective view showing the structure of a VA-mode liquid crystal display device according to Embodiment 9 of the present invention. The relationship between the lamination of each film and the axial direction is shown in Fig. 30 and Table 9.

The VA mode liquid crystal display device of the present embodiment is shown in Figure 30, except that the first anisotropic scattering film 10a is pasted on one side of the observation surface of the liquid crystal display device 15a, so that the VA mode liquid crystal display device 15a is at an azimuth angle Φ The azimuth (minimum azimuth) of =45 degrees is substantially identical to the axial orientation _S1 of the scattering central axis of the first anisotropic scattering film 10a, and has the same configuration as the VA mode liquid crystal display device of Example 1.

[Table 9]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 45 degree 1st polarizer 13a-observation side (absorption axis a) 0～180 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 1st retardation film 12a (slow axis s) 0～180 degrees 1st polarizer 13a-back side (absorption axis a) 90～270 degrees

<Example 10>

FIG. 31 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 10 of the present invention. Figure 31 and Table 10 show the relationship between the lamination of each film and the axial direction.

The VA mode liquid crystal display device of the present embodiment is as shown in Figure 31, except that the first anisotropic scattering film 10a is pasted on the viewing surface side of the liquid crystal display device 15a, so that the VA mode liquid crystal display device 15a is at an azimuth angle Φ The azimuth (minimum azimuth) of =45 degrees is substantially identical to the axial orientation _S1 of the scattering central axis of the first anisotropic scattering film 10a, and has the same configuration as the VA mode liquid crystal display device of Example 2.

[Table 10]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 45 degree Polarizer 3a-observation side (absorption axis a) 0～180 degrees Second retardation film 12b (slow axis s) 90～270 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 3rd retardation film 12c (slow axis s) 0～180 degrees Polarizing element 3a-back side (absorption axis a) 90～270 degrees

<Example 11>

FIG. 32 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 11 of the present invention. Figure 32 and Table 11 show the relative relationship between the lamination of each film and the axial direction.

The VA mode liquid crystal display device of the present embodiment is shown in Figure 32, except that the first anisotropic scattering film 10a is pasted on one side of the observation surface of the liquid crystal display device 15a, so that the VA mode liquid crystal display device 15a is at an azimuth angle Φ The azimuth (minimum azimuth) of =45 degrees is substantially identical to the axial orientation _S1 of the scattering center axis of the first anisotropic scattering film 10a, and has the same configuration as the VA mode liquid crystal display device of Example 3.

[Table 11]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 45 degree 1st polarizer 13a-observation side (absorption axis a) 0～180 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 4th retardation film 12d (slow axis s) 0～180 degrees 1st polarizer 13a-back side (absorption axis a) 90～270 degrees

<Example 12>

FIG. 33 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 12 of the present invention. Figure 33 and Table 12 show the relative relationship between the lamination of each film and the axial direction.

The VA-mode liquid crystal display device of the present embodiment is shown in Figure 33, except that the first anisotropic scattering film 10a is pasted on the viewing surface side of the liquid crystal display device 15a, so that the VA-mode liquid crystal display device 15a is positioned at the azimuth angle Φ The azimuth (minimum azimuth) of =45 degrees is substantially the same as the axial azimuth _S1 of the scattering central axis of the first anisotropic scattering film 10a, and has the same configuration as the VA mode liquid crystal display device of Example 4.

[Table 12]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 45 degree Polarizer 3a-observation side (absorption axis a) 0～180 degrees Fifth retardation film 12e (slow axis s) 90～270 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees 6th retardation film 12f (slow axis s) 0～180 degrees Polarizing element 3a-back side (absorption axis a) 90～270 degrees

<Example 13>

FIG. 34 is a schematic perspective view showing the configuration of a VA-mode liquid crystal display device 100a according to Embodiment 13 of the present invention. Figure 34 and Table 13 show the relationship between the lamination of each film and the axial direction.

The VA-mode liquid crystal display device of the present embodiment is shown in Figure 34, except that the first anisotropic scattering film 10a is pasted on the viewing surface side of the liquid crystal display device 15a, so that the VA-mode liquid crystal display device 15a is positioned at the azimuth angle Φ The azimuth (minimum azimuth) of =45 degrees is substantially identical to the axial orientation _S1 of the scattering center axis of the first anisotropic scattering film 10a, and has the same configuration as the VA-mode liquid crystal display device of Example 5.

[Table 13]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 45 degree Polarizer 3a-observation side (absorption axis a) 0～180 degrees 7th retardation film 12g (slow axis s) 90～270 degrees VA mode liquid crystal cell 11a (tilt orientation of liquid crystal molecules) 45, 135, 225, 315 degrees Eighth retardation film 12h (slow axis s) 0～180 degrees Polarizing element 3a-back side (absorption axis a) 90～270 degrees

<Example 14>

FIG. 35 is a schematic perspective view showing the configuration of a TN-mode liquid crystal display device 100b according to Embodiment 14 of the present invention. Figure 35 and Table 14 show the relationship between the lamination of each film and the axial direction.

The TN-mode liquid crystal display device of the present embodiment is shown in Figure 35, except that the first anisotropic scattering film 10a is pasted on the viewing surface side of the liquid crystal display device 15b, so that the TN-mode liquid crystal display device 15b is at the azimuth angle Φ The azimuth (minimum azimuth) of =270 degrees is substantially the same as the axial orientation _S1 of the scattering center axis of the first anisotropic scattering film 10a, and has the same configuration as the TN mode liquid crystal display device of Example 6.

[Table 14]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 270 degrees Polarizer 3b-observation side (absorption axis a) 45～225 degrees WV film 4-observation surface side (orientation control direction of liquid crystal b) 45 degree TN mode liquid crystal cell 11b (alignment control direction d of liquid crystal) 45 degrees (observation side), 315 degrees (rear side) WV film 4-back side (alignment control direction b of liquid crystal) 315 degrees Polarizing element 3b-back side (absorption axis a) 135～315 degrees

<Example 15>

(Production of the second anisotropic scattering film)

The production method of the first anisotropic scattering film was the same as that of the first anisotropic scattering film, except that ultraviolet light was irradiated vertically for one minute from the epi-radiation irradiation unit of the UV spot light source (trade name: L2859-01, manufactured by Hamamatsu Photonics Co., Ltd.) with an irradiation intensity of 30 mW/ ^cm2 . Thus, a second anisotropic scattering film was obtained. In the second anisotropic scattering film, when the cross-section was observed with a microscope, it was confirmed that there were rod-shaped solidified regions 20 extending in the normal direction of the film surface as shown in FIG. 2C .

(Measurement of the scattering characteristics of the second anisotropic scattering film)

Fig. 5 is a graph showing the relationship between the incident angle and the amount of linearly transmitted light when the second anisotropic scattering film is rotated around two mutually orthogonal rotation axes (longitudinal axis and short-side axis). The solid line in the figure shows the case where the short-side axis is rotated, and the broken line shows the case where the long-side axis is rotated. In addition, the positive and negative angles of incidence indicate that the direction of rotation is opposite.

The scattering characteristics of the second anisotropic scattering film were measured in the same manner as the first anisotropic scattering film. It can be seen from FIG. 5 that the second anisotropic scattering film is in the shape of a deep valley including hills at an incident angle of 0 degrees, showing roughly bilaterally symmetrical anisotropy in both the cases where the short-side axis is rotated and the case where the long-side axis is rotated. Anisotropic scattering properties. In addition, it can be seen that the second anisotropic scattering film exhibits substantially the same anisotropic scattering characteristics when the short-side axis is rotated and when the long-side axis is rotated. From this, it can also be seen that the second anisotropic scattering film has a scattering center axis along the normal direction of the film surface. In addition, the rate of change of the linear transmitted light amount was 0.90 both in the case of rotating the short-side axis and in the case of rotating the long-side axis.

(Fabrication of TN Mode Liquid Crystal Display Device 200b)

FIG. 36 is a schematic perspective view showing the structure of a TN-mode liquid crystal display device 200b according to Embodiment 15 of the present invention. Figure 36 and Table 15 show the relative relationship between the lamination of each film and the axial direction.

Example 14 is the same as that of Example 14 except that the second anisotropic scattering film 10b is attached to the observation surface side of the TN mode liquid crystal display device 15b instead of the first anisotropic scattering film 10a. In addition, since the second anisotropic scattering film 10b has a scattering center axis in the normal direction of the film surface, it is considered to have the axis orientation S ₁ of the scattering center axis in all directions.

[Table 15]

Components Azimuth Φ Second Anisotropic Scattering Film 10b (Axial Orientation S ₁ of Scattering Central Axis) All directions Polarizer 3b-observation side (absorption axis a) 45～225 degrees WV film 4-observation surface side (orientation control direction of liquid crystal b) 45 degree TN mode liquid crystal cell 11b (alignment control direction d of liquid crystal) 45 degrees (observation side), 315 degrees (rear side) WV film 4-back side (alignment control direction b of liquid crystal) 315 degrees Polarizing element 3b-back side (absorption axis a) 90～270 degrees

<Example 16>

FIG. 37 is a schematic perspective view showing the configuration of an IPS mode liquid crystal display device 100c according to Embodiment 16 of the present invention. Figure 37 and Table 16 show the relationship between the lamination of each film and the axial direction.

The IPS mode liquid crystal display device of the present embodiment is as shown in Figure 37, except that the first anisotropic scattering film 10a is pasted on the viewing surface side of the liquid crystal display device 15c, so that the IPS mode liquid crystal display device 15c is at an azimuth angle Φ The azimuth (minimum azimuth) = 45 degrees is approximately the same as the axial orientation _S1 of the scattering central axis of the first anisotropic scattering film 10a, and has the same configuration as the IPS mode liquid crystal display device of Example 7.

[Table 16]

Components Azimuth Φ First Anisotropic Scattering Film 10a (Axial Orientation S ₁ of Scattering Central Axis) 45 degree 9th polarizer 13j-observation side (absorption axis a) 0～180 degrees IPS mode liquid crystal cell 11c (alignment control direction d of liquid crystal) 90～270 degrees Ninth retardation film 12j (slow axis s) 90～270 degrees 9th polarizer 13j-back side (absorption axis a) 90～270 degrees

<Example 17>

In the OCB mode liquid crystal display device of this embodiment, the first anisotropic scattering film is pasted on the viewing side of the OCB mode liquid crystal display device, so that the OCB mode liquid crystal display device is in the orientation of the azimuth angle Φ=0 degree (polar Small orientation) has the same configuration as the OCB mode liquid crystal display device of Example 8, except that the axis orientation _S1 of the scattering central axis of the first anisotropic scattering film is approximately the same.

<Comparative example 3>

The VA mode liquid crystal display device of this comparative example is except that LUMISTY (registered trademark) is pasted on the viewing surface side of the VA mode liquid crystal display device 15a, so that the VA mode liquid crystal display device 15a is at the orientation of the azimuth angle Φ=45 degrees (polar Small azimuth) and the viewing angle control film (product name: LUMISTY (registered trademark), model: MFY-1060, manufactured by Sumitomo Chemical Co., Ltd.) approximately coincide with the scattering direction, and have the same configuration as the VA mode liquid crystal display device of Comparative Example 2.

4. Measurement of Optical Properties of the Liquid Crystal Display Devices of Examples 9 to 17 and Comparative Examples 1 and 3

Using a viewing angle measuring device (trade name: EZContrast160R, manufactured by ELDIM Corporation), in the liquid crystal display devices of Examples 9 to 17 and Comparative Examples 1 and 3, the black display time (gray value: 0 ), halftone display (grayscale value: 128), and white display (grayscale value: 225) viewing angle dependence of brightness and chromaticity. The viewing angle is represented by the polar angle Θ and the azimuth angle Φ.

<Evaluation of viewing angle-dependent improvement of contrast ratio>

In each liquid crystal display device, the polar angle dependence of the contrast ratio of the liquid crystal display device in the direction in which the contrast ratio of the liquid crystal display device is extremely small in the direction of polar angle Θ = 45 degrees (minimum azimuth) was evaluated. That is, in the liquid crystal display devices of VA mode and IPS mode, the azimuth angles Φ=45, 135, 225, and 315 degrees were evaluated, and in the liquid crystal display devices of TN mode and OCB mode, the azimuth angles Φ=0, 90, Polar angle dependence of the contrast ratio in four directions such as 180 and 270 degrees.

In addition, the contrast ratio was obtained by the above formula (3) from the measured luminance at the time of black display (gradation value: 0) and the time of white display (gradation value: 255).

The polar angle dependence of the contrast ratio of the liquid crystal display devices and liquid crystal display devices of Examples 9 to 17 and Comparative Examples 1 and 3 in extremely small orientations is shown in FIGS. 38A to 48A and 38B to 48B. The solid line in each figure shows the polar-angle dependence of the contrast ratio of the liquid crystal display device, and the dotted line shows the polar-angle dependence of the contrast ratio of the liquid crystal display device.

FIGS. 38A to 48A show the polar angle dependence of the contrast ratio in two minimal azimuths of the axial orientation substantially parallel to the scattering central axis of the first anisotropic scattering film 10a or the second anisotropic scattering film 10b. FIG. 38B ˜48B represent the polar angle dependence of the contrast ratio in two azimuths perpendicular to the minimum azimuth.

In the VA-mode liquid crystal display devices of Examples 9 to 13 of the present invention, it can be seen from FIGS. 38A to 42A that in the minimum orientation (orientation with an azimuth angle Φ=45 degrees) approximately coincident with the axis orientation of the scattering center axis, In the vicinity of the axial direction of the scattering central axis (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the viewing angle dependence of the contrast ratio is improved. In addition, under the orientation opposite to the minimum orientation (the orientation of the azimuth angle Φ=225 degrees) and the two orientations perpendicular to the minimum orientation (the orientations of the azimuth angles Φ=135 and 270 degrees), from FIGS. 38A to 42A From 38B to 42B, it can be seen that there is no influence such as a decrease in the contrast ratio.

However, in the VA mode liquid crystal display device of Comparative Example 1, as shown in FIGS. 47A and 47B , the contrast ratio was not improved in any direction. In addition, in the VA mode liquid crystal display device of Comparative Example 3, as shown in FIG. 48A , although the viewing angle is improved in the extremely small azimuth (the azimuth angle Φ = 45 degrees) that substantially coincides with the scattering direction, the viewing angle is improved. However, as shown in FIG. 48B As shown, the contrast ratio is very low in a wide range in the two azimuths approximately perpendicular to the scattering direction (the azimuth angles Φ=135 and 270 degrees), and in the frontal direction (the direction of the polar angle Θ=0 degrees) The resulting maximum contrast ratio is also very low.

In addition, in the TN mode liquid crystal display device according to Example 14 of the present invention, it can be seen from FIG. 43A that in the minimum azimuth (orientation with azimuth angle Φ=270 degrees) approximately coincident with the axial orientation of the scattering central axis, the scattering central axis In the vicinity of the axial direction (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the effect of improving the viewing angle dependence of the contrast ratio is obtained. In addition, on the direction opposite to the minimum direction (the direction with the azimuth angle Φ=90 degrees) and the two directions perpendicular to the minimum direction (the direction with the direction angle Φ=0 and 180 degrees), from FIGS. 43A and 43B It can be seen that there is no influence such as a decrease in the ratio.

In addition, in the TN-mode liquid crystal display device of Example 15 of the present invention, it can be seen from FIGS. 44A and 44B that the maximum contrast obtained in the direction inclined by 10 degrees from the normal direction of the observation surface to the azimuth angle of 180 degrees is basically not obtained. The ratio drops, improving the viewing angle dependence of the contrast ratio in the 4 minimal azimuths (azimuth angles Φ = 0, 90, 180, 270 degrees).

In addition, in the IPS mode liquid crystal display device according to Example 16 of the present invention, it can be seen from FIG. 45A that in the minimum azimuth (the azimuth angle Φ = 45 degrees) that roughly coincides with the axial orientation of the scattering central axis, the scattering central axis In the vicinity of the axial direction (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the effect of improving the viewing angle dependence of the contrast ratio can be obtained. In addition, on the direction opposite to the minimum direction (the direction with the azimuth angle Φ=225 degrees) and the two directions perpendicular to the minimum direction (the direction with the direction angles Φ=135 and 315 degrees), from FIGS. 45A and 45B It can be seen that there is no influence such as a decrease in the ratio.

In addition, in the OCB mode liquid crystal display device according to Example 17 of the present invention, it can be seen from FIG. 46A that at the minimum orientation (the orientation at which the azimuth angle Φ=0 degrees) approximately coincides with the axial orientation of the scattering central axis, the scattering central axis In the vicinity of the axial direction (the direction of the polar angle Θ = 30 degrees), the contrast ratio is improved, and the effect of improving the viewing angle dependence of the contrast ratio can be obtained. In addition, in the direction opposite to the minimum direction (the direction with the azimuth angle Φ = 180 degrees) and the two directions perpendicular to the minimum direction (the direction with the azimuth angle Φ = 90 and 270 degrees), from Figs. 46A and 46B It can be seen that there is no influence such as a decrease in the ratio.

This is explained below as follows. According to the liquid crystal display devices of Examples 9 to 17 of the present invention, since the first anisotropic scattering film or the second anisotropic scattering film is pasted on the viewing surface side of the liquid crystal display device, the axis of the central axis of scattering The orientation is approximately the same as the orientation (minimum orientation) in which the contrast in the direction inclined 45 degrees from the normal direction of the observation surface of the liquid crystal display device is the minimum orientation (minimum orientation), and the light incident in the axial direction approximately parallel to the scattering central axis ( Black luminance) is diffused (diffused) in all directions centered on the central axis of scattering and averaged, so that the viewing angle dependence of the contrast ratio can be improved at least in an extremely small orientation that approximately coincides with the axis of the central axis of scattering. In addition, the first anisotropic scattering film shows the scattering characteristics shown in FIG. 7, and the second anisotropic scattering film shows the scattering characteristics shown in FIG. The light incident in the direction from the direction is only weakly scattered, so it is possible to suppress the deterioration of the display quality in the direction where the contrast ratio is high due to the scattering of the light incident from the direction.

On the contrary, according to the liquid crystal display device of Comparative Example 1, since the isotropic scattering film used instead of the first anisotropic scattering film or the second anisotropic scattering film exhibits the scattering characteristics shown in FIG. The incident light is scattered in all directions and averaged, so the viewing angle dependence of the contrast ratio cannot be improved. In addition, according to the liquid crystal display device of Comparative Example 3, since LUMISTY (registered trademark) used instead of the first anisotropic scattering film or the second anisotropic scattering film shows anisotropic scattering characteristics only in a specific orientation, it is not In a direction showing anisotropic scattering characteristics, incident light in a direction with a low contrast ratio is strongly scattered, and as a result, the maximum contrast ratio obtained in the frontal direction or the like decreases due to scattering of incident light in this direction.

<Evaluation of improvement in gamma curve deviation>

Obtain the gamma curve on the front direction (the direction of polar angle Θ=0 degree) and the oblique direction (polar angle Θ=40 degree, and the orientation is the contrast ratio of each liquid crystal display device on the direction of polar angle Θ=40 degree γ curves in 4 directions of the minimum orientation), normalize the luminance under each grayscale display, set the white display luminance to 1, and calculate the normalized luminance in the front direction when the halftone display (grayscale value: 128) and each The difference (deviation amount) of the normalized luminance in the oblique direction. Table 17 shows the ratio of the improvement effect from the liquid crystal display device. That is, the larger the numerical value described in the table, the larger the effect of improvement.

[Table 17]

Φ＝45 degrees Φ＝135 degrees Φ＝225 degrees Φ＝315 degrees Example 9 40 20 18 twenty one Example 10 37 19 20 17 Example 11 43 16 25 twenty three Example 12 39 20 twenty four 26 Example 13 48 25 16 20 Comparative example 1 8 12 11 14 Comparative example 3 42 10 15 13

It can be seen from Table 17 that in the liquid crystal display devices of Examples 9 to 13 of the present invention, the γ-curve deviation improvement effect is achieved in the minimum orientation (orientation with an azimuth angle Φ=45 degrees) that is roughly consistent with the axis orientation of the scattering center axis. big. In addition, in the three minimum azimuths (azimuth angles Φ = 135, 225, and 315 degrees) other than the minimum azimuth, the deviation-improving effect of the γ curve can also be obtained. However, in the liquid crystal display device of Comparative Example 1, the effect of improving deviation of the γ curve was small in any minimum orientation. In addition, in the liquid crystal display device of Comparative Example 3, although the effect of improving the deviation of the γ curve is large in the extremely small azimuth (the azimuth angle Φ = 45 degrees) that substantially coincides with the scattering direction, the viewing angle of the above-mentioned contrast ratio As shown in the evaluation results of dependency improvement, the maximum contrast ratio decreased significantly.

This is explained below as follows. The γ curve of a VA mode liquid crystal display device is usually optimally designed in the direction in which the contrast ratio is the largest, and its viewing angle dependence shows the same tendency as that of the contrast ratio. According to the liquid crystal display devices of Examples 9 to 13 of the present invention and Comparative Example 3, since the first anisotropic scattering film and LUMISTY (registered trademark) show anisotropic scattering characteristics in at least one direction, when the respective films are attached When combined on the viewing surface side of the VA mode liquid crystal display device, by making the orientation representing the anisotropic scattering characteristics of each film roughly consistent with the minimum orientation of the VA mode liquid crystal display device, in this minimum orientation, it can be greatly improved. Improve viewing angle dependence of gamma curve. According to the liquid crystal display devices of Examples 9 to 13 of the present invention, since the first anisotropic scattering film exhibits anisotropic scattering characteristics in all directions, even in the directions approximately corresponding to the directions showing the anisotropic scattering characteristics of each film, The viewing angle dependence of the γ curve can also be improved in the three minimum orientations other than the minimum orientation. In contrast, according to the liquid crystal display device of Comparative Example 1, since the isotropic scattering film used instead of the first anisotropic scattering film did not show anisotropic scattering characteristics, it was not possible to scatter incident light from a specific direction in all directions and Averaging is performed, and as a result, viewing angle dependence of the γ curve cannot be improved.

"Above" and "below" in the specification of this application include the numerical value.

This application is based on Japanese Patent Application No. 2006-41456 filed on February 17, 2006, Japanese Patent Application No. 2006-41457 and Japanese Patent Application No. 2007-15240 filed on January 25, 2007, and Japanese Patent Application No. 2007-15241 No. 1, claiming priority based on the Paris Convention. The entire content of this application is incorporated in this application by reference.

Claims (17)

1. display device possesses: the anisotropic scattering film that contrast ratio has the display device of view angle dependency and has anisotropic scattering layer, it is characterized in that,

This anisotropic scattering film with direction behind the sightingpiston normal direction inclination certain angle of display device on contrast ratio get on the roughly consistent orientation, the orientation of extreme value, have the scattering center axle, and be disposed at sightingpiston one side of display device.

2. display device according to claim 1 is characterized in that, described extreme value is a maximum value.

3. display device according to claim 1 is characterized in that, described extreme value is a minimal value.

4. display device according to claim 1 is characterized in that, described scattering center axle is roughly consistent with the normal direction of the sightingpiston of display device.

5. display device according to claim 1 is characterized in that, described scattering center axle with direction behind the sightingpiston normal direction inclination certain angle of display device on contrast ratio get roughly consistent orientation, the orientation of extreme value and tilt.

6. display device according to claim 1, it is characterized in that, described anisotropic scattering film with the certain angle that tilts from the sightingpiston normal direction of display device more than 20 degree after direction on contrast ratio get on the roughly consistent orientation, the orientation of extreme value, have the scattering center axle.

7. display device according to claim 1, it is characterized in that, described anisotropic scattering film with 45 degree that tilt from the sightingpiston normal direction of display device after direction on contrast ratio get on the roughly consistent orientation, the orientation of extreme value, have the scattering center axle.

8. display device according to claim 1 is characterized in that, described anisotropic scattering layer solidifies the constituent that comprises photocurable compound and makes.

9. display device according to claim 1 is characterized in that,

The straight line that described anisotropic scattering film has on the direction of principal axis that straight line is the scattering center axle through light quantity sees through the following direction of light quantity,

It is consistent to see through the orientation that the orientation of the direction below the light quantity and the contrast ratio on the direction behind the sightingpiston normal direction inclination certain angle of display device get extreme value as this straight line.

10. display device according to claim 9 is characterized in that, the axle orientation of described scattering center axle is below 15 degree with the orientation angulation that the contrast ratio on the direction behind the sightingpiston normal direction inclination certain angle of display device is got extreme value.

11. display device according to claim 10 is characterized in that, the axle orientation of described scattering center axle is below 10 degree with the orientation angulation that the contrast ratio on the direction behind the sightingpiston normal direction inclination certain angle of display device is got extreme value.

12. display device according to claim 1, it is characterized in that, in the described anisotropic scattering film, the direction that straight line sees through the light quantity minimum and the direction of principal axis angulation of scattering center axle are littler than the direction of principal axis angulation that straight line sees through the direction of light quantity maximum and scattering center axle.

13. display device according to claim 1 is characterized in that, described anisotropic scattering film is on any one orientation, and straight line is littler through the polar angle of the direction of light quantity maximum than straight line through the polar angle of the direction of light quantity minimum.

14. display device according to claim 1, it is characterized in that, described anisotropic scattering film is on the axle orientation of scattering center axle, and polar angle sees through the maximal value of light quantity than the straight line on the little direction of scattering center axle less than polar angle through the maximal value of light quantity than the straight line on the big direction of scattering center axle.

15. display device according to claim 1 is characterized in that, described display device is a liquid crystal display device.

16. display device according to claim 15 is characterized in that, described liquid crystal display device has: clamping has the liquid crystal cells of liquid crystal and comprises support film and the polarized light piece of polarization element between a pair of substrate.

17. display device according to claim 15 is characterized in that, the display mode of described liquid crystal display device is VA pattern, TN pattern, IPS pattern or ocb mode.

Images