JP2003279988A - Liquid crystal display and electronic equipment - Google Patents

Abstract

(57) [Problem] To provide a liquid crystal display device capable of securing a certain level of visibility even in a bright use environment. SOLUTION: The liquid crystal display device of the present invention has a liquid crystal cell 15 in which a liquid crystal layer 27 is sandwiched between a counter substrate 3 and an element substrate 2.
And the backlight 1 arranged on the outer surface side of the liquid crystal cell 15
8 is provided. An upper polarizing plate 20 is provided on the outer surface side of the counter substrate 3.
The lower polarizing plate 23, the forward scattering layer 28, and the prism sheets 31 and 32 are provided in this order between the element substrate 2 and the backlight 18 from the substrate side. In addition, a reflection plate 29 is provided on the outer surface side of the light guide plate 16 of the backlight 18. The absolute value of the intersection angle between the extension direction of the light refraction surface 31a of the prism sheet 31 and the transmission axis of the lower polarizing plate is less than 45 degrees.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and an electronic apparatus, and more particularly to the structure of a liquid crystal display device mainly including a transmissive display, which includes an illumination device.

[0002]

2. Description of the Related Art As a liquid crystal display device capable of displaying even in a dark place, an illuminating device (hereinafter also referred to as a backlight) is provided on the back side of a liquid crystal cell, and display is performed by utilizing light emitted from the illuminating device. There is a transmissive liquid crystal display device. The illuminator used here is generally a cold cathode fluorescent lamp (C
CFL), a light emitting diode (LED), and the like, and a light guide plate having a structure for emitting the light incident from the light source to the liquid crystal cell side while propagating inside.

An active matrix type liquid crystal display device is known as a liquid crystal display device having high definition and excellent display quality. As a display method of an active matrix type liquid crystal device, Twisted Nema
The tic (hereinafter abbreviated as TN) mode display method is currently the mainstream. The reason is that the TN mode liquid crystal device balances various characteristics basically required for a display, such as bright, high contrast, relatively fast response speed, low drive voltage, and easy gradation display. This is because they are well equipped. In the case of a TN mode liquid crystal cell, a structure is adopted in which the major axis direction of liquid crystal molecules is twisted by 90 ° between the element substrate and the counter substrate, and polarizing plates are respectively provided on the outer surfaces of these substrates so that their transmission axes are orthogonal to each other. It is arranged.

FIG. 11 shows a schematic structure of the above-mentioned conventional liquid crystal display device. In this device, the upper polarizing plate A, the upper substrate B, the liquid crystal layer C, the
A lower substrate D, a lower polarizing plate E, and a prism sheet F are arranged,
Further, a backlight having a light source G and a light guide plate H is arranged behind it, and a reflector J is arranged behind the light guide plate H.

Here, by disposing the prism sheet F between the liquid crystal cell and the backlight, light having a large emission angle with respect to the normal line of the surface of the light guide plate H out of the light emitted from the backlight. The prism sheet F allows light to be condensed, and the amount of light of the backlight that contributes to display is increased.

However, in this type of liquid crystal display device, due to the display principle, the light R emitted from the backlight is in an indefinite polarization state.
Among b, only the polarized light having one oscillating direction is taken out by the lower polarizing plate E and the upper polarizing plate A to be transmitted light Rt, which is used for display. In the case of the conventional liquid crystal display device, since the polarizing plates A and E arranged above and below the liquid crystal cell are absorption type polarizing plates, polarized light not used for display is absorbed by the polarizing plates. That is, the conventional liquid crystal display device has a problem that only about half of the light emitted from the backlight contributes to the display and the utilization efficiency of the irradiation light of the backlight is low.

In order to deal with this problem, a liquid crystal display device having a reflective polarizing plate (hereinafter simply referred to as "reflective polarizing plate") R shown by a dotted line in FIG. was suggested. In the case of this liquid crystal display device, the polarized light Rc which is not used for display among the light emitted from the light guide plate H is reflected by the reflective polarizing plate R, and the polarized light Rc is provided on the outer surface of the light guide plate H of the backlight. Then, it will be reflected by the light source and returned to the reflective polarizing plate R again. However, even if some depolarization occurs during that time, the light returns almost in the polarization state reflected by the reflective polarizing plate R at the beginning, so that it is transmitted through the reflective polarizing plate R and used for display. The light that becomes is only a little, and it has not been possible to sufficiently improve the utilization efficiency of the light of the backlight.
Generally speaking, in the conventional transmissive liquid crystal display device, the display is dark relative to the brightness of the backlight, and it has been required to realize brighter transmissive display by increasing the utilization efficiency of the light of the backlight. .

Therefore, as a method of improving the utilization efficiency of the light of the backlight, a liquid crystal display device having a quarter wavelength plate behind the reflective polarizing plate R has been proposed. When a quarter wavelength plate is arranged behind the reflection polarizing plate R, when linearly polarized light Rc in one polarization direction reflected by the reflection polarizing plate R passes through the quarter wavelength plate, it is converted into, for example, clockwise circular polarization. To be done.
When this right-handed circularly polarized light is reflected by a reflector installed on the outer surface of the light guide plate of the backlight, this time it returns as left-handed (reverse) circularly polarized light and passes through the quarter-wave plate. After passing through the / 4 wavelength plate, it is converted into linearly polarized light whose polarization axis is orthogonal to that before transmission. Then, since this linearly polarized light is transmitted through the reflective polarizing plate R this time, it can be used for display. As described above, when the quarter-wave plate is used, a large amount of light emitted from the backlight and reflected by the reflective polarizing plate R can be reused, and thus bright transmissive display can be obtained. This technique is disclosed in, for example, Japanese Unexamined Patent Publication No. 10-162619 and Japanese Unexamined Patent Publication 2000-98.
No. 372, etc.

[0009]

By the way, in recent years, this type of transmissive liquid crystal display device has been adopted for an image display section of a mobile phone, an image display section of a digital camera, etc., and has the advantages of small size and light weight. It is widely used mainly for various portable electronic devices. Since the utilization efficiency of the light of the backlight is improved by the above technique, the brightness of the transmissive display is also improved year by year. However, the transmissive liquid crystal display device has the following major drawbacks when applied to portable electronic devices. That is, depending on the environment in which the portable electronic device is used, the brightness of the backlight is much weaker than sunlight, for example, in the outdoors where the sunlight is strong, so the image displayed on the liquid crystal screen is very dark and very difficult to see. There was a problem.

As a method for solving this problem, for example, increasing the output of a backlight that illuminates the liquid crystal panel can be considered. However, when the output of the backlight is increased, the power consumption of the backlight is increased, so that a large capacity power supply device is required. This is not practical for electronic devices where portability is important.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to obtain a bright display by increasing the light utilization efficiency and to secure a certain degree of visibility even in a bright use environment. It is an object of the present invention to provide a liquid crystal display device that can be manufactured. In particular, it aims to obtain a bright display by increasing the substantial reflection efficiency of external light.

[0012]

In order to achieve the above object, a liquid crystal display device of the present invention comprises a liquid crystal cell in which a liquid crystal is sandwiched between a first substrate and a second substrate which are arranged to face each other. ,
A liquid crystal display device comprising a light source and a light guide plate, and an illuminating device arranged on the outer surface side of the second substrate of the liquid crystal cell, wherein a first polarized light is provided on the outer surface side of the first substrate. A plate is provided, and a prism sheet having a second polarizing plate, a light scattering layer, and an inclined light refracting surface is provided in this order from the second substrate side between the second substrate and the lighting device. A reflection plate is provided on a surface of the light guide plate opposite to the side where the liquid crystal cell is arranged, and a crossing line with respect to a virtual plane orthogonal to an optical axis of the light refracting surface and a transmission axis of the second polarizing plate. The crossing angle θ between and is set within the range of −45 ° <θ <45 °.

In the conventional liquid crystal display device, as shown in FIG. 11, when the prism sheet F is arranged behind the liquid crystal cell after the external light Ro is incident and transmitted through the liquid crystal cell, the prism Since the light is dissipated by the sheet F and does not return to the observation side, the brightness of the outside light Ro cannot be used for display. In addition, since the external light Ro is often incident obliquely at an angle from a direction different from the observer, the incident angle with respect to the display surface becomes large.
Is a reflected light Rr (that is, light returning by regular reflection) that is reflected by a reflector J disposed behind the light guide plate H.
However, since the light is inclined with respect to the display surface, there is a problem that it does not return to the observer's side and is not used for display.

On the other hand, in the present invention, as shown in FIG. 10, the upper polarizing plate A, the upper substrate B, the liquid crystal layer C, the lower substrate D,
The light scattering layer S was arranged behind the liquid crystal cell having the lower polarizing plate E. Further, the crossing angle θ between the line of intersection of the light refracting surface f of the prism sheet F arranged further on the backlight side of the light scattering layer S and the plane orthogonal to the optical axis and the transmission axis of the lower polarizing plate E is It is set within the range of −45 ° <θ <45 °. As a result, a part of the external light that has entered the liquid crystal cell can be efficiently reflected on the surface of the prism sheet F, and the reflected light can be used for display, so that the contrast is improved particularly in a bright place. Have an effect on.

For example, in the above structure, of the illumination light Rb emitted from the light source G, the illumination light obliquely emitted from the light guide plate H is condensed by the prism sheet F and then passes through the light scattering layer S. Then, after being scattered, it becomes the transmitted light Rt that exits the liquid crystal cell toward the observation side, that is, along the optical axis. This is the same as the conventional structure except for the presence or absence of scattering by the light scattering layer S.

When external light enters the liquid crystal cell due to a bright place or the like, the external light Ro passes through the liquid crystal cell and is scattered by the light scattering layer S. Part of the scattered light is a prism sheet. After passing through F, it is reflected by the reflector J through the light guide plate H and becomes reflected light Rr, which again passes through the light guide plate H, the prism sheet F, and the light scattering layer S, and then passes through the liquid crystal cell to cause reflected light Rr1. Is emitted as. As described above, the external light reflected by the reflection plate J is rarely directed to the viewing side and is rarely used as a part of the display in the conventional structure. However, in the present invention, the light scattering layer is used. Since S is arranged, a part thereof contributes to the display as reflected light Rr1.

Further, a part of the scattered light generated when the incident external light Ro reaches the light scattering layer S is orthogonal to the light refracting surface f of the prism sheet F and the optical axis with respect to the transmission axis of the lower polarizing plate E. The intersection angle θ of the intersection line with the virtual plane is −45 ° <θ <45
Since the angle is 0, the light is reflected on the surface of the prism sheet S, and then is transmitted through the liquid crystal cell again as reflected light Rr2 and emitted. This is because, of the external light Ro incident on the liquid crystal cell, only the polarized component having the vibration direction parallel to the transmission axis of the lower polarizing plate E passes through the liquid crystal cell, and this polarized component is The line of intersection between the light refracting surface f and the virtual plane orthogonal to the optical axis is −4 with respect to the transmission axis of the lower polarizing plate E.
This is because when the light beams intersect at a crossing angle θ of 5 ° <θ <45 °, they are efficiently reflected and the reflected light Rr2 can sufficiently contribute to display.

Consider, for example, a case where a line of intersection between the light refracting surface f of the prism sheet F and an imaginary plane orthogonal to the optical axis is parallel to the transmission axis of the lower polarizing plate E. The light transmitted through the liquid crystal cell is linearly polarized light having a vibration direction parallel to the transmission axis of the lower polarizing plate E, and after being scattered by the light scattering layer S, is reflected on the light refracting surface f of the prism sheet F. Incident. At this time, the above-mentioned linearly polarized light becomes s-polarized light that is incident on the light refracting surface f, and therefore is reflected more efficiently than when it is p-polarized light. Then, most of the reflected light passes through the lower polarizing plate E. By the way, if the incident angle of the linearly polarized light incident from the lower polarizing plate with respect to the light refracting surface f is the Brewster angle, the reflected light is only s-polarized light,
All the reflected light composed of this s-polarized light passes through the lower polarizing plate E again. Therefore, under this condition, the light transmitted through the liquid crystal cell can be reflected most efficiently on the light refracting surface f of the prism sheet F.

Further, the intersection line between the light refracting surface f of the prism sheet F and the virtual plane orthogonal to the optical axis is not limited to the case where it is parallel to the transmission axis of the lower polarizing plate E as described above. If the absolute value of the intersection angle θ with the transmission axis is less than 45 degrees as described above, the polarized light entering the prism sheet F from the observation side has an s-polarized component larger than a p-polarized component. The intensity of the reflected light Rr2 can be increased.

In the present invention, the intersection angle θ is -30 °.
It is preferably set within a range of ≦ θ ≦ 30 °.

According to the present invention, since the absolute value of the intersection angle θ is 30 degrees or less, the reflected light Rr2 is
Since the intensity of is increased, the display can be brightened especially in a bright place.

In the present invention, it is preferable that the light refracting surface is provided on the surface of the prism sheet on the liquid crystal cell side.

According to this invention, since the light refracting surface is provided on the liquid crystal cell side surface of the prism sheet,
Light caused by external light can be more efficiently reflected on the surface.

In the present invention, the prism sheet is
It is preferable that the plurality of light refraction surfaces are formed in a stripe shape extending in a predetermined direction and are inclined in a direction orthogonal to the predetermined direction.

According to the present invention, the plurality of light refracting surfaces are formed in stripes extending in a predetermined direction and are inclined in a direction orthogonal to the predetermined direction, so that the light refracting surface is virtually orthogonal to the optical axis. Since the line of intersection with the plane extends in the predetermined direction, which is constant, the intensity of the reflected light Rr2 can be further increased.

In the present invention, the prism sheet is
It is preferable that the light refracting surface is arranged so as to extend left and right when used.

According to the present invention, in a normal use state, external light incident from above is stronger than external light incident from other directions (for example, illumination and sunlight are emitted from above). ), The scattered light generated in the light-scattering layer S based on the external light Ro incident from the strong oblique upper direction is directed to the observation side by the prism sheet F arranged so that the stripe-shaped light refracting surface f extends to the left and right. Since the effect of collecting light is obtained, the visibility can be further improved.

In the present invention, the prism sheet is
It is preferable to have a function of condensing the light emitted from the illumination device on the observation side.

According to the present invention, by having the function of condensing the light emitted from the illuminating device to the observation side, the utilization efficiency of the illuminating device in displaying the illuminating light can be increased and the display can be made brighter. You can Here, the observation side means the normal direction (optical axis direction) of the display screen of the device.

In the present invention, it is preferable that another prism sheet having a light refracting surface inclined in a direction different from the light refracting surface of the prism sheet is further disposed on the side of the prism sheet facing the illuminating device.

According to the present invention, by disposing another prism sheet having a light refracting surface inclined in different directions, it becomes possible to collect the light emitted from the illumination device also in the different directions. Therefore, the utilization efficiency of the irradiation light of the lighting device can be further improved. Further, since another prism sheet is arranged on the side of the prism sheet on the illuminating device side, the effect of the reflected light Rr2 can be maintained.

In the present invention, it is preferable that the light scattering layer is a forward scattering layer that mainly causes forward scattering.

According to the present invention, since the light scattering layer is a forward scattering layer which mainly produces forward scattering, the reflector J
Since it is possible to scatter to the observation side, any of the reflected light Rr1 that is reflected by, the reflected light Rr2 that is reflected by the light refracting surface of the prism sheet, and the irradiation light Rb from the light guide plate H of the illumination device. It is possible to suppress the decrease in the brightness of the display and improve the contrast by increasing the whiteness of the display.

In the present invention, the haze of the forward scattering layer is preferably 60% or more.

According to the present invention, since the haze (cloudiness value) of the forward scattering layer is 60% or more, the deviation of the emission angles of the reflected lights Rr1 and Rr2 due to the external light can be reduced, and the display can be achieved. It is possible to increase the light component that contributes to the display to brighten the display, and it is possible to further increase the whiteness of the display. Further, any material having a haze of 60% or more can be easily obtained. In particular, it is preferable that the numerical value range of haze is within the range of 60 to 80% because the availability can be ensured and the reduction of light utilization efficiency can be suppressed.

The "haze" used herein is a measure showing the light transmission property generally called "haze" or haze value in the field of optics, and it is within a cone of 8 degrees around the normal of the substance. It is a value expressed in% by dividing the diffuse transmittance of the angle portion excluding the area by the total light transmittance. A larger haze value means more scattered light, and a smaller haze value means less scattered light. The function of the forward scattering layer of the present invention is desirable in that the larger the haze, the higher the effect of reducing the display unevenness caused by the light guide plate, but on the other hand, the emitted light from the lighting device is scattered. , The transparent display will be dark. Therefore, it is necessary to optimize the balance. When the haze value is 60% or more, the display unevenness caused by the light guide plate can be sufficiently reduced without significantly reducing the display brightness.

It is desirable that the forward scattering layer has an adhesive and particles mixed in the adhesive and having a refractive index different from that of the adhesive. With this configuration, the layers disposed before and after the forward scattering layer function as an adhesive layer that bonds the layers to each other, and at the same time, the layer has a forward scattering function. Can be simplified.

In the present invention, the retardation value of the light scattering layer is preferably 10 nm or less.

According to the present invention, the retardation value of the light scattering layer, that is, the value of Δn · d (where Δn is the optical anisotropy and d is the thickness) is 10 nm or less. Since the change in the polarization state due to the retardation is suppressed to a negligible degree, the light loss in the external light reflection process due to the change in the polarization state due to the light scattering layer can be reduced. For example, when the linearly polarized light generated after the outside light Ro has passed through the liquid crystal cell passes through the light scattering layer, if the polarization state of the scattered light generated by the light scattering layer changes, the light of the second polarizing plate is correspondingly changed. Since the amount of transmission decreases, the reflected light Rr1
However, according to the present invention, the light amount of Rr2 and Rr2 decreases.
A reduction in the amount of reflected light can be substantially suppressed.

The light scattering layer is preferably a filler-type scattering material in which fillers having different refractive indexes are dispersed in the base material. This makes it possible to easily form the forward scattering layer and suppress the retardation value thereof to a low value.

In the present invention, it is preferable that a reflective polarizing plate is arranged between the second polarizing plate and the illuminating device.

According to the present invention, of the light emitted from the backlight, the polarized component not directly used for display can be reflected to the backlight side by the reflective polarizing plate, so that at least a part of the polarized component can be reflected. It can be used for display in some form.

In the present invention, it is preferable that the first retardation plate is arranged on the side opposite to the side where the liquid crystal cell is arranged with respect to the reflective polarizing plate.

According to the present invention, with respect to the light emitted from the illuminating device, the polarization component in the direction orthogonal to the transmission axis of the reflection polarizing plate is reflected by the reflection polarizing plate.
About half of that becomes impossible to transmit to the observation side, but by disposing the first retardation plate, it is possible to change the polarization state of the polarization component reflected by the reflection polarizing plate, and thus the polarization component After the light is reflected by the reflection plate, at least a part of the light can be allowed to pass through the reflection polarizing plate, so that the brightness of the display can be further increased.

In the present invention, the first retardation plate is
It is preferable to include at least a quarter wave plate.

According to the present invention, in the process in which the above-mentioned polarized component reflected by the reflective polarizing plate is reflected by the reflective plate and returns to the reflective polarizing plate again, 1/4 before and after the reflection by the reflective plate. By passing through the wave plate twice, the polarized component can be rotated by 90 degrees and converted into polarized light having a polarization direction that coincides with the transmission axis of the reflective polarizing plate, so that the reflective polarizing plate is efficiently transmitted. Will be able to.

Further, in the present invention, it is desirable that the first retardation plate includes a quarter wave plate and a half wave plate. However, in this case, it is necessary to dispose a half-wave plate on the reflective polarizing plate side.

According to the present invention, a quarter wave plate and a half wave plate are used.
A wave plate in combination with a wave plate is known as a broadband quarter wave plate, and according to this configuration, the illumination light can be reused in a wide wavelength band.

In the present invention, it is desirable that the retardation value of the first retardation plate is in the range of 100 nm to 180 nm.

According to this structure, the wavelength is 380 to 780.
Most of the visible light band of nm can be covered, and the function as the first retardation plate in the liquid crystal display device of the present invention can be fulfilled with respect to visible light.

In the present invention, it is desirable that the wavelength dispersion of the first retardation plate has a value of 1 or less.

For example, when the wavelength dispersion is represented by the ratio of the retardation value at the wavelength of 450 nm and the retardation value at the wavelength of 590 nm, the retardation plate commercially available in the past usually has a wavelength dispersion of more than 1. On the other hand, in recent years, a retardation plate having a wavelength dispersion of 1 or less has been provided. When this retardation plate is used, the fact that the chromatic dispersion takes a value of 1 or less means that the retardation value increases as the wavelength becomes longer. For example, in the case of a 1/4 wavelength plate, the incident light 1 even if the wavelength changes
It will function as a quarter-wave plate. Therefore, according to this configuration, the first aspect of the present invention can be applied to light of different wavelengths.
Can function as a retardation plate.

In the present invention, it is preferable that the first retardation plate is arranged closer to the lighting device than the prism sheet.

According to the present invention, since the first retardation plate is arranged closer to the illuminating device than the prism sheet, the polarization state of the light incident on the prism sheet from the second polarizing plate is not changed. Since the light can be reflected by the light refracting surface of the prism sheet, the effect of the present invention is not affected, and the effect can be prevented from lowering.

In the present invention, it is desirable that the reflecting surface of the reflecting plate disposed on the outer surface side of the light guide plate of the illuminating device should be a mirror surface.

The reflecting plate in the present invention not only guides the light emitted from the illuminating device to the liquid crystal cell side first, but also functions to reuse the reflected light from the reflecting polarizing plate in the transmissive display. In addition, in the reflective display, a function of reflecting external light that has passed through the light diffusion layer is fulfilled. Therefore, it is required to reflect more light, and in that sense, it is desirable to make the reflecting surface a mirror surface.

Further, it is desirable to provide a second retardation plate between the first polarizing plate and the first substrate or between the second polarizing plate and the second substrate. .

According to this structure, for example, STN (Super
Twisted Nematic) Even if the display is colored, such as when a liquid crystal is used, the coloring can be compensated.

By the way, there are the following two possible relations between the transmission axis of the second polarizing plate and the transmission axis of the reflecting polarizing plate.

First, the transmission axis of the second polarizing plate and the transmission axis of the reflecting polarizing plate are parallel to each other. According to this structure, all the light transmitted through the reflective polarizing plate in the transmissive display can be transmitted through the transmission axis of the second polarizing plate, so that the light use efficiency in the transmissive display can be maximized.

On the other hand, the transmission axis of the second polarization plate and the transmission axis of the reflection polarization plate are made to intersect each other in a plane, and the arrangement is made so that the angle ψ between them is in the range of 0 ° <ψ <10 °. You can also In the case of this configuration, contrary to the above configuration, part of the light transmitted through the reflective polarizing plate in the transmissive display cannot pass through the transmission axis of the second polarizing plate, so that the light utilization efficiency in the transmissive display is high. It is slightly lower than the configuration. On the other hand, in the reflective display, a part of the light transmitted through the transmission axis of the second polarizing plate is reflected by the reflective polarizing plate, so that the reflective display can be slightly brightened. The reason why the angle ψ formed by the transmission axis of the second polarizing plate and the transmission axis of the reflective polarizing plate is preferably 0 ° <φ <10 ° will be described later.

The display mode of the liquid crystal display device of the present invention is preferably a normally white mode.

According to this structure, a black display screen on a white background can be realized with low power consumption.

It is desirable to use absorption type polarizing plates as the first polarizing plate and the second polarizing plate.

According to this structure, a high contrast display can be obtained.

An electronic apparatus of the present invention is characterized by including the liquid crystal display device of the present invention.

According to this structure, by providing the liquid crystal display device of the present invention, it is possible to realize a portable electronic device having a bright display screen suitable for use outdoors, for example, in strong sunlight. it can.

[0068]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. The liquid crystal display device of the present embodiment is a thin film transistor (Thin Film).
Transistor, abbreviated as TFT hereinafter) is an example of an active matrix type transmissive liquid crystal display device using a switching element, and FIG. 1A is a perspective view showing the entire configuration of the liquid crystal display device. 2) is an enlarged view of one pixel in FIG. 1A, and FIG. 2 is a sectional view of the liquid crystal display device. In all of the following drawings, in order to make the drawings easy to see, the film thicknesses, the dimensional ratios, and the like of the respective constituent elements are appropriately changed. In addition, in FIG. 2, wirings, switching elements, electrodes, alignment films, etc. on the inner surface side of each substrate are omitted.

The liquid crystal display device 1 of the present embodiment is similar to that shown in FIG.
As shown in (a), it is roughly composed of a liquid crystal cell 15, a light guide plate 16 arranged on the outer surface side thereof, and a backlight 18 (illumination device) having an LED 17 (light source). In the liquid crystal cell 15, the element substrate 2 (second substrate) on the side where the TFT is formed and the counter substrate 3 (first substrate) are arranged to face each other, and a liquid crystal layer (not shown) is provided between these substrates 2 and 3. Is enclosed. On the inner surface side of the element substrate 2, a large number of source lines 4 and a large number of gate lines 5 are provided in a grid pattern so as to intersect each other. TFTs 6 are formed near the intersections of the source lines 4 and the gate lines 5, and the pixel electrodes 7 are connected via the TFTs 6, respectively. That is,
One TFT 6 and one pixel electrode 7 are provided for each pixel arranged in a matrix. On the other hand, one common electrode 8 is formed on the entire inner surface of the counter substrate 3 over the entire display area in which a large number of pixels are arranged in a matrix. In this specification, the surface of each substrate constituting the liquid crystal cell 15 on the liquid crystal layer side is referred to as an “inner surface”, and the opposite surface is referred to as an “outer surface”.

As shown in FIG. 1B, the TFT 6 has a gate electrode 10 extending from the gate line 5 and a gate electrode 10.
An insulating film (not shown) covering the semiconductor layer, a semiconductor layer 11 formed on the insulating film and made of polycrystalline silicon, amorphous silicon, or the like, and a source line 4 electrically connected to a source region in the semiconductor layer 11. It has a source electrode 12 and a drain electrode 13 electrically connected to a drain region in the semiconductor layer 11. The drain electrode 13 of the TFT 6 is electrically connected to the pixel electrode 7. The pixel electrode 7 is formed of a transparent conductive film such as ITO, and the common electrode 8 on the counter substrate 3 side is also formed of a transparent conductive film such as ITO.

Looking at the sectional structure of the liquid crystal display device 1, FIG.
As shown in, the upper glass substrate 19 constituting the counter substrate 3
An upper polarizing plate 20 (first polarizing plate) is provided on the outer surface of the above, and a color filter 21 having R (red), G (green), and B (blue) color material layers is provided on the inner surface side. Although not shown, a common electrode and an alignment film are formed on the color filter 21.

On the other hand, on the outer surface of the lower glass substrate 22 forming the element substrate 2, the lower polarizing plate 23 is provided from the lower glass substrate 22 side.
(Second Polarizing Plate), Forward Scattering Layer 28, Prism Sheet 3
1, 32 are provided in this order. Further, although not shown, the above-mentioned gate line 5, source line 4, TFT 6, pixel electrode 7 are formed on the inner surface side of the lower glass substrate 22, and an alignment film is formed. A liquid crystal layer 27 made of TN liquid crystal having a positive dielectric anisotropy is enclosed between the substrates 2 and 3. Further, specifically, both the upper polarizing plate 20 and the lower polarizing plate 23 are constituted by absorption type polarizing plates.

The forward scattering layer 28 is a transparent base material in which transparent and fine particles having a different refractive index from the base material are dispersed, whereby light is scattered mainly forward. Have a function. That is, most of the scattered light generated by the forward scattering layer 28 becomes forward scattered light. The forward scattering layer 28 is made of, for example, an acrylic resin having a thickness of about 10 to 50 μm, preferably about 20 to 30 μm (for example, a photorefractive index = 1.55) and an acrylic resin having a different photo-curing state. A large number of fine particles or beads (for example, optical refractive index = 1.6) of 2 to 3 μm are dispersed.

By disposing the front scattering layer 28 as described above, the external light transmitted through the liquid crystal cell 15 can be scattered toward the prism sheet 31. Therefore, the incident angle of external light on the prism sheet 31 can be dispersed. Further, by configuring the forward scattering layer with a filler-type scattering material as described above, forward scattering can be easily realized and the retardation value described later can be suppressed to be small.

Further, the retardation value (Δn · d; Δn is optical anisotropy, d is thickness) of the forward scattering layer 28 is 10 nm.
The following are desirable. Since the forward scattering layer 28 is disposed between the liquid crystal cell 15 and the prism sheet 31, if the retardation value is large, the linearly polarized state emitted from the liquid crystal cell 15 is canceled and the effect of the present invention is reduced. Because.

The haze (cloudiness value) of the forward scattering layer 28 is 6
It is preferably 0% or more. A particularly practical range of haze is 60 to 80%. If the haze is less than 60%, the effect of reducing display unevenness due to the light guide plate is reduced, and if it exceeds 80%, the amount of light that can contribute to the display is affected and the display becomes dark.

The forward scattering layer 28 preferably has an adhesive property. In this case, for example, an acrylic resin-based pressure-sensitive adhesive mixed with fine particles (beads) having a refractive index different from that of the pressure-sensitive adhesive and having a particle diameter of, for example, 2 to 3 μm is used. Since the front scattering layer 28 has adhesiveness, it can also have a function as an adhesive for adhering the members arranged on both front and back sides to each other. For example, the liquid crystal cell 15 and the prism sheet 3
1 and 1 can be bonded.

The prism sheets 31 and 32 are provided with light refracting surfaces 31a and 32a on the surface on the observation side (upper side in the drawing). These light refracting surfaces 31a and 32a are surfaces inclined with respect to the optical axis (vertical direction in the drawing) and are configured to refract light entering from the backlight 18 side and light entering from the observing side. ing. Prism sheet 31,
The contour of the surface of 32 is formed in a saw-tooth shape as a whole, and a plurality of light refracting surfaces 31a and 32a are provided in stripes extending in a predetermined direction. That is, strip-shaped light refracting surfaces 31a and 32a inclined on opposite sides are alternately arranged to form a stripe shape as a whole.

The light refracting surface 31a of the prism sheet 31 is
The prism sheet 32 extends in a direction orthogonal to the paper surface of FIG.
The light refracting surface 32a extends in a direction parallel to the paper surface of FIG. That is, the extending direction of the light refracting surface 31a and the extending direction of the light refracting surface 32a are orthogonal to each other.

As shown in FIG. 3A, the extension direction of the light refracting surface 31a of the prism sheet 31, that is, the extension direction D of the line of intersection between the light refracting surface 31a and a virtual plane orthogonal to the optical axis is below. It intersects the transmission axis T of the polarizing plate 23 at a crossing angle θ. Here, the intersection angle θ is ideally 0, but it may be in the range of −45 ° <θ <45 °.
Among these, it is desirable that the range is −30 ° ≦ θ ≦ 30 °. Here, the extension direction D corresponds to the light refraction surface 31.
It is the direction in which the line of intersection between a and a virtual plane orthogonal to the optical axis (that is, a plane parallel to the paper surface of FIG. 3A) extends.

Returning to FIG. 2 again, the liquid crystal display device 1 will be described. The backlight 18 has a light guide plate 16 and a light source 17 such as an LED arranged on the incident end face thereof, and the light guide plate 16 has, on the outer surface side thereof, a reflector plate 2 having a mirror-finished surface.
9 is provided. Here, the light guide plate 16 is the liquid crystal cell 1.
5 and the light source 17 are arranged so as to overlap each other in a plane.
Are arranged beside the light guide plate 16.

Regarding the axial arrangement of the respective polarizing plates, the upper polarizing plate 20 and the lower polarizing plate 23 are arranged so that their transmission axes are orthogonal to each other. The alignment films formed on the element substrate 2 and the counter substrate 3 are subjected to a rubbing process in a direction orthogonal to each other, and the liquid crystal layer 27 sandwiched between these alignment films is 9
It is in a 0 ° twisted state. Further, in the following description, the intersection angle θ = 0, that is, the prism sheet 31.
Direction of the light refracting surface 31a, that is, the light refracting surface 31a
Extension direction D of the line of intersection between a and a virtual plane orthogonal to the optical axis
Will be described respectively for a case where it is configured to be parallel to the transmission axis T of the lower polarizing plate 23 and a case where θ is not 0 but within the above range.

In this embodiment, of the light emitted from the backlight 18, for example, linearly polarized light having a vibration direction perpendicular to the paper surface passes through the lower polarizing plate 23 and enters the liquid crystal layer 27. In the state in which no voltage is applied, the light transmitted through the liquid crystal layer 27 has its polarization direction rotated by 90 °, is converted into linearly polarized light having a vibration direction parallel to the paper surface, and is transmitted through the upper polarizing plate 20 to display white (normally). White mode). On the other hand, when a voltage is applied, the polarization direction remains perpendicular to the plane of the paper even though it passes through the liquid crystal layer 27, so that this polarization cannot pass through the upper polarizing plate 20, resulting in black display. In the present embodiment, by adopting the normally white mode, a black display screen on a white background can be realized with low power consumption.

In this case, since the light emitted from the backlight 18 passes through the prism sheets 32 and 31 and is condensed in the direction along the optical axis, the light visually recognized on the observation side, that is, the display is displayed. The light utilized can be increased. Here, the prism sheet 31 has a function of condensing light inclined in the left-right direction in the drawing (direction parallel to the paper surface of the drawing), and the prism sheet 32 has a function of condensing light inclined in a direction orthogonal to the paper surface. Have.

The light emitted from the backlight 18 passes through the prism sheets 31 and 32 and is then scattered forward (that is, on the observation side) by the front scattering layer 28. This has the effect of reducing variations in brightness caused by the light collected by the prism sheets 31 and 32.

On the other hand, when the liquid crystal display device 1 is used in a bright place, the outside light mainly enters from the upper side of the liquid crystal cell 15 in the drawing (including the observation direction, but normally, it is slightly inclined with respect to the observation direction. External light is incident from. Of this incident light, linearly polarized light having a vibration direction parallel to the paper surface passes through the upper polarizing plate 20 and enters the liquid crystal layer 27. In the state where no voltage is applied, the light transmitted through the liquid crystal layer 27 has its polarization direction rotated by 90 degrees, is converted into linearly polarized light having a vibration direction perpendicular to the paper surface, passes through the lower polarizing plate 23, and is then scattered by the forward scattering layer 28. Receive. Then, the forward scattered light from the forward scattering layer 28 enters the surface of the prism sheet 31. Figure 3
(B) is an enlarged cross-sectional view of the prism sheet 31.

Here, the above scattered light Rs is reflected by the lower polarizing plate 23.
Is a linearly polarized light parallel to the transmission axis of, and the crossing angle is θ = 0.
If it is, since the surface of the prism sheet 31, that is, the light refracting surface 31a is s-polarized Ps, at least a part thereof is mainly reflected by the light refracting surface 31a, and the liquid crystal is again reflected. The light passes through the cell 15 and returns to the observation side.
In this case, since the scattered light Rs is almost s-polarized with respect to the light refracting surface 31a, it is efficiently reflected by the light refracting surface 31a. Here, if the incident angle of the scattered light Rs on the light refracting surface 31a coincides with the Brewster's angle, only the s-polarized light Ps reflects on the light refracting surface 31a, so that all the reflected light is transmitted through the lower polarizing plate 23.

When the intersection angle θ is not 0,
The scattered light Rs has s-polarized light Ps with respect to the light refracting surface 31a.
Not only that, but the p-polarized light Pp is also included, but if the crossing angle θ is a value in the above range (absolute value is less than 45 degrees), half or more of it is s-polarized light Ps, so the crossing angle θ is in the above range. The amount of light reflected by the light refracting surface 31a is increased and the amount of light transmitted through the lower polarizing plate 23 is also increased as compared with the case of being outside. Here, the point that the reflected light of the scattered light Rs whose incident angle to the light refracting surface 31a matches the Brewster's angle is only the s-polarized light Ps is the same as above.

The light refracting surface 31 of the prism sheet 31 described above.
The reflected light generated by the light reflection by a is reflected by the forward scattering layer 28.
In addition to being based on scattered light that has been scattered by and scattered angularly, the surface of the prism sheet 31 also has a condensing function. Therefore, for example, when a large amount of external light enters from a direction that is inclined to some extent with respect to the optical axis. However, the reflected light contains many components emitted in the direction along the optical axis. Therefore, the display becomes bright, and it is possible to prevent the display from becoming difficult to see even in a bright place where the external light is particularly strong.

In this embodiment, as shown in FIG. 3A, a plurality of light refracting surfaces 31a are formed on the surface of the prism sheet 31.
Are arranged in a stripe pattern. In this case, as the liquid crystal display device 1, the light refracting surface 31 of the prism sheet 31 is used.
It is preferable that the extension direction D of a is the left-right direction of the display screen. This is because when the left and right direction of the display screen is the extension direction D, when the external light is incident obliquely from above the display screen (that is, when the external light is obliquely incident from the left side in the drawing), the prism sheet 31 is exposed. Due to the condensing action, the reflected light from the surface of the prism sheet 31 based on the external light can be efficiently emitted to the observing side (optical axis direction, that is, the direction normal to the display surface), and the normal use state. In, the sun and lighting fixtures are placed above,
This is because the light is incident from diagonally above the display screen, and the strongest external light can be used as the reflected light that contributes to the display.

As described above, according to the liquid crystal display device 1 of the present embodiment, most of the external light having a high incident angle can be returned to the observation side, so that it is possible to obtain some visibility even in a bright environment of use. A color liquid crystal display device that can be secured can be realized.

Further, in this embodiment, since the forward scattering layer 28 is arranged to scatter light, the brightness of the display can be increased and the contrast can be improved. In particular, since the action of the forward scattering layer 28 is mainly for forward scattering, light can be efficiently used for display. Further, by setting the haze of the forward scattering layer 28 to 60% or more as described above, the effect of improving the contrast can be particularly enhanced.

Further, as the color filter 21, the spectral characteristic of G, which has the highest visibility for human eyes, has a minimum transmittance of 10% or more in the visible light range, and an average transmittance of R, G, and B colors of 40% or more. As described above, by using a color filter having a relatively high transmittance and a light color, it is possible to realize both bright transmissive display and reflective display.

[Second Embodiment] Next, referring to FIG.
A second embodiment according to the present invention will be described. In this embodiment, the upper polarizing plate 20, the upper glass substrate 19, the color filter 21, the lower glass substrate 22, the lower polarizing plate 23, the front scattering layer 28, and the prism sheets 31 and 3 shown in FIG.
2, the light source 17, the light guide plate 16 and the reflection plate 29 are exactly the same as in the first embodiment, and the structure not shown in FIG. 4 is also exactly the same as in the first embodiment.
These same parts are designated by the same reference numerals, and description thereof will be omitted.

In this embodiment, the reflection polarizing plate 24 is arranged between the front scattering plate 28 and the prism sheet 31. As the reflective polarizing plate 24, for example, a so-called DBEF (trade name, manufactured by 3M) is used. The reflective polarizing plate 24 transmits a polarization component having a vibration direction in the transmission axis direction, and reflects a polarization component having a vibration direction in a direction orthogonal to the transmission axis.

Here, the lower polarizing plate 23 and the reflective polarizing plate 24 are arranged so that their transmission axes are parallel to each other. Since the reflective polarizing plate 24 is arranged, the polarized component of the light emitted from the backlight 18 and having the vibration direction parallel to the paper surface of the drawing is reflected without being absorbed. This reflected light is reflected on the surface of the prism sheet 31, or passes through the prism sheets 31 and 32 and returns to the inside of the light guide plate 16 and is reflected by the reflection plate 29. And
In a part of this reflected light, the prism sheet 31,
If the polarization state changes due to refraction, reflection, etc. by 32, part of the reflected light may eventually pass through the lower polarization plate 23 and the reflection polarization plate 24 and become light that contributes as part of the display.

In this embodiment, the transmission axis of the lower polarization plate 23 and the transmission axis of the reflection polarization plate 24 are parallel to each other, but the transmission axis of the lower polarization plate 23 and the transmission axis of the reflection polarization plate 24 are planar. They may be crossed and arranged so that the angle ψ between them is in the range of 0 ° <ψ <10 °. In the case of this configuration, in the transmissive display, part of the light transmitted through the reflective polarizing plate 24 is part of the lower polarizing plate 2.
3 cannot pass through the transmission axis, and the light use efficiency in transmissive display is slightly reduced, but in reflective display, the lower polarizing plate 23
Since a part of the light transmitted through the transmission axis is reflected by the reflective polarizing plate 24, the reflective display can be made slightly brighter.

Further, in this embodiment, the forward scattering layer 2
8 and the reflective polarizing plate 24 may be arranged on the prism sheet 31 side.

[Third Embodiment] Next, referring to FIG.
A third embodiment according to the present invention will be described. In this embodiment, the upper polarizing plate 20, the upper glass substrate 19, the color filter 21, the lower glass substrate 22, the lower polarizing plate 23, the front scattering layer 28, the reflecting polarizing plate 24, the prism sheets 31 and 32 shown in FIG. The light source 17, the light guide plate 16 and the reflection plate 29 are exactly the same as those in the second embodiment, and
Since the structure not shown in FIG. 5 is completely the same as that of the second embodiment, these same parts are designated by the same reference numerals,
These explanations are omitted.

In this embodiment, as shown in FIG. 5, a quarter wavelength plate 26 (first retardation plate) is arranged further on the backlight 18 side of the reflective polarizing plate 24. In particular, it is preferable that the prism sheet 31 is arranged closer to the backlight 18 side. More specifically, in the present embodiment, the quarter wave plate 26 is the prism sheet 3
It is arranged on the backlight 18 side with respect to 1, 32.

In this embodiment, of the light emitted from the backlight 18, the linearly polarized light having the vibration direction parallel to the paper surface reflected by the reflection polarizing plate 24 is the quarter wavelength plate 2
By passing through 6, the light is converted into clockwise circularly polarized light, for example. This right-handed circularly polarized light is reflected by the reflection plate 29 or the like and then returns as left-handed circularly polarized light to pass through the quarter-wave plate 26. Therefore, after passing through the quarter-wave plate 26, it is perpendicular to the paper surface. It is converted into linearly polarized light having a vibration direction. Since this linearly polarized light can pass through the reflective polarizing plate 24 and the lower polarizing plate 23, it can be used for display. Thus, by reusing the reflected light from the reflective polarizing plate 24, the transmissive display can be made brighter. Particularly in the case of the present embodiment, since the transmission axis of the lower polarizing plate 23 and the transmission axis of the reflecting polarizing plate 24 are parallel to each other, the reflecting polarizing plate 24 is used in the transmissive display.
Since all the light transmitted through the lower polarizing plate 23 can be transmitted, it is possible to maximize the light utilization efficiency in the transmissive display.

In order to obtain the above effect, 1 /
The four-wave plate 26 has a liquid crystal cell 15 rather than the prism sheet 31.
May be arranged on the side of. However, when the quarter wave plate is arranged closer to the liquid crystal cell 15 than the prism sheet 31, external light enters the liquid crystal cell 15,
The linearly polarized light transmitted through the liquid crystal cell 15 is a quarter wavelength plate 2
Since the polarization state of the prism sheet 31 changes, such as circularly polarized light, the amount of reflected light reflected by the light refracting surface 31a of the prism sheet 31 may decrease, and the effect peculiar to the present invention may be impaired. Therefore, it is preferable that the quarter-wave plate 26 is disposed at least on the backlight 18 side of the prism sheet 31.

As the quarter-wave plate 26, a normal one made of polycarbonate or the like may be used, but if possible, it is preferable to use one having a wavelength dispersion of 1 or less. Or
A ½ wavelength plate may be further inserted on the inner surface side of the ¼ wavelength plate 26. The retardation value of the quarter-wave plate 26 is 1
It is preferably in the range of 00 nm to 180 nm. In that case, it can function as a quarter-wave plate for all visible light.

In the above embodiment, the first retardation plate was described as a quarter wave plate, but the first retardation plate may be, for example, a quarter wave plate or a half wave plate. Various phase plates other than the wave plate can be used. However, it is desirable to include at least a quarter wave plate.

That is, the first retardation plate is not necessarily 1 /
Even if it is not a four-wave plate, when the polarized light that is once reflected on the lower surface of the reflective polarization plate is reflected by the reflective plate on the outer surface of the lighting device and then returns, polarization conversion occurs at the first retardation plate and the reflected polarized light is generated. Since some component that can be transmitted through the plate is generated, the effect of reusing the reflected light is inevitably produced as compared with the case where the first retardation plate is not provided, regardless of the magnitude of the effect. However, as described above, when the first retardation plate is a quarter-wave plate, when the polarized light that was once reflected on the lower surface of the reflective polarizing plate is reflected again and then returned, theoretically, Since 100% of polarized light can pass through the reflective polarizing plate, all can contribute to display. Therefore, the reuse efficiency can be maximized, and brighter transmissive display can be obtained as compared with the case where another retardation plate is used.

[Fourth Embodiment] Next, referring to FIG.
A fourth embodiment according to the present invention will be described. In this embodiment, the upper polarizing plate 20, the upper glass substrate 19, the color filter 21, the lower glass substrate 22, the lower polarizing plate 23, the reflective polarizing plate 24, the quarter wavelength plate 26, and the forward scattering layer 28 shown in FIG. The prism sheets 31 and 32, the light source 17, the light guide plate 16 and the reflection plate 29 are exactly the same as those in the third embodiment, and the structure not shown in FIG. 6 is also exactly the same as that in the third embodiment. The same parts are designated by the same reference numerals, and the description thereof will be omitted.

This embodiment is different from the third embodiment in that the forward scattering layer 28 is arranged closer to the backlight 18 than the reflective polarizing plate 24. However, it is the same as the third embodiment in that the forward scattering layer 28 is arranged closer to the liquid crystal cell 15 than the prism sheet 31. In this embodiment, only the scattering position by the forward scattering layer 28 is different, and the polarization state is the same as that in the third embodiment. Therefore, also in the liquid crystal display device of the present embodiment, it is possible to obtain the same effect as described above such that it is possible to realize a liquid crystal display device that can secure a certain degree of visibility even in a bright use environment.

Further, in this embodiment, the phase difference plate (1/4 wavelength plate 26) may not be interposed as in the second embodiment.

[Electronic Equipment] Lastly, examples of electronic equipment equipped with the liquid crystal display device of each of the above embodiments will be described. FIG. 7 is a perspective view showing an example of a mobile phone. In FIG. 7, reference numeral 1000 indicates a mobile phone body, and reference numeral 100.
Reference numeral 1 denotes a display unit using the above liquid crystal display device.

FIG. 8 is a perspective view showing an example of a wrist watch type electronic device. In FIG. 8, reference numeral 1100 indicates a watch body, and reference numeral 1101 indicates a display section using the above liquid crystal display device.

FIG. 9 is a perspective view showing an example of a portable information processing device such as a word processor or a personal computer. In FIG. 9, reference numeral 1200 is an information processing apparatus, reference numeral 1202 is an input unit such as a keyboard, reference numeral 1204 is the information processing apparatus main body, and reference numeral 1206 is a display unit using the above liquid crystal display device.

Since the electronic apparatus shown in FIGS. 7 to 9 is equipped with the liquid crystal display device of the above-mentioned embodiment, it is equipped with a bright (color) liquid crystal display unit suitable for use outdoors, for example, in strong sunlight. It is possible to realize a portable electronic device.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, a retardation plate (second retardation plate) may be provided between the upper polarizing plate and the upper glass substrate or between the lower polarizing plate and the lower glass substrate. Although the TN liquid crystal is used in the above-described embodiment, even when the display is colored, especially when the STN liquid crystal is used, the color difference can be compensated by providing the retardation plate.

Example Next, the present inventor actually made a prototype of the TFT transmissive color liquid crystal display device of the first embodiment shown in FIG. 2 and observed the display in order to prove the effect of the present invention. At the same time, the display contrast (value obtained by dividing the brightness of white display by the brightness of black display) was measured. Less than,
The results will be reported. Here, the prism sheet 3
The contrast was measured by changing the crossing angle θ between the groove direction 1 (extension direction D above) and the transmission axis T of the lower polarizing plate 23 as follows.

In this liquid crystal display device, a filler type scattering plate having a haze value of 80% and a retardation value of 10 nm or less was used as the forward scattering layer 28. The brightness of the backlight 18 is 2000 [cd / m ² ],
The brightness of this liquid crystal display device is 200 [cd / m
2], the display contrast in the dark room was 200. Further, with the groove direction of the prism sheet 31 aligned with the left-right direction of the display screen, the contrast was measured at a place (about 100,000 lux) having the same brightness as in the field on a sunny day. The results are shown in Table 1 below.

[0116]

[Table 1]

As described above, in a bright place, the intersection angle θ
Although the display is recognizable at −45 ° <θ <45 °, the display cannot be recognized beyond this range. Further, in the range of the intersection angle θ of −30 ° <θ <30 °, sufficient contrast was obtained as the display quality.

Next, with the above intersection angle θ = 0, a plurality of front scattering layers having different hazes were replaced and the contrast was measured in the same manner as above. The results are shown in Table 2.

[0119]

[Table 2]     Haze value of the forward scattering layer Contrast          10 1.8          30 2.1          45 2.6          60 5.2          80 15.1          95 15.0

As shown in Table 2, when the haze value of the forward scattering layer was 60 or more, the contrast capable of visually confirming the display was obtained.

Although the embodiments described above exemplify the active matrix type liquid crystal display device, the present invention can be similarly applied to the passive matrix type liquid crystal display device.

[0122]

As described above in detail, according to the present invention, it is possible to realize a liquid crystal display device capable of ensuring a certain degree of visibility even in a bright environment where the sun is strong, such as outdoors.

[Brief description of drawings]

FIG. 1 is a diagram showing a liquid crystal display device according to a first embodiment of the present invention, FIG. 1 (a) is a perspective view showing the entire configuration of the liquid crystal display device, and FIG. 1 (b) is FIG. 1 (a). 3 is an enlarged view of one pixel in FIG.

FIG. 2 is a cross-sectional view showing the liquid crystal display device.

FIG. 3 is an enlarged sectional view (a) showing an enlarged sectional structure of a prism sheet used in the liquid crystal display device and a plan view (b) showing the structure of the prism sheet and its back side.

FIG. 4 is a sectional view schematically showing a liquid crystal display device according to a second embodiment of the present invention.

FIG. 5 is a sectional view schematically showing a liquid crystal display device according to a third embodiment of the present invention.

FIG. 6 is a sectional view schematically showing a liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing an example of an electronic apparatus using the liquid crystal display device of the present invention.

FIG. 8 is a perspective view showing another example of an electronic device.

FIG. 9 is a perspective view showing still another example of an electronic device.

FIG. 10 is a schematic explanatory diagram for explaining a display principle of the liquid crystal display device of the present invention.

FIG. 11 is a schematic explanatory diagram for explaining a display principle of a conventional liquid crystal display device.

[Explanation of symbols]

1. Liquid crystal display device 2 ... Element substrate (second substrate) 3 ... Counter substrate 15 ... Liquid crystal cell 16 ... Light guide plate 17 ... Light source 18 ... Backlight (illumination device) 20 ... Upper polarizing plate (first polarizing plate) 21 ... Color filter 23 ... Lower polarizing plate (second polarizing plate) 24 ... Reflective polarizing plate 26 ... Quarter-wave plate (first retardation plate) 27 ... Liquid crystal layer 28 ... Forward scattering layer 29 ... Reflector 31, 32 ... Prism sheet 31a, 32a ... Photorefractive surface D: Extension direction of light refracting surface of prism sheet T: Transmission axis of lower polarizing plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 5/30 G02B 5/30 G02F 1/1335 G02F 1/1335 510 510 510 520 520 1/13363 1/13363 / / F21Y 101: 02 F21Y 101: 02 F term (reference) 2H042 AA26 BA04 BA12 BA20 CA12 DA01 DA11 DA21 2H049 BA02 BA05 BA06 BA07 BA43 BB03 BB62 BB63 BB66 BC22 2H091 FA08X FA08Z FA02ZFA45Z FA23Z FA45 LA18

Claims (24)

[Claims] 1. A liquid crystal cell in which a liquid crystal is sandwiched between a first substrate and a second substrate which are arranged to face each other, a light source and a light guide plate, and the liquid crystal cell is provided on the outer surface side of the second substrate. A liquid crystal display device provided with an illuminating device arranged, wherein a first polarizing plate is provided on an outer surface side of the first substrate, and the first polarizing plate is provided between the second substrate and the illuminating device. A second polarizing plate, a light scattering layer, and a prism sheet having an inclined light refracting surface are provided in this order from the second substrate side, and are reflected on the surface of the light guide plate opposite to the side where the liquid crystal cell is arranged. A plate is provided, and an intersection angle θ between an intersection line with respect to an imaginary plane orthogonal to the optical axis of the light refracting surface and a transmission axis of the second polarizing plate is within a range of −45 ° <θ <45 °. A liquid crystal display device characterized by being set. 2. The liquid crystal display device according to claim 1, wherein the intersection angle θ is set within a range of −30 ° ≦ θ ≦ 30 °. 3. The liquid crystal display device according to claim 2, wherein the light refracting surface is provided on a surface of the prism sheet on the liquid crystal cell side. 4. The prism sheet, wherein the plurality of light refracting surfaces are formed in a stripe shape extending in a predetermined direction and are inclined in a direction orthogonal to the predetermined direction. 4. The liquid crystal display device according to any one of item 3. 5. The liquid crystal display device according to claim 4, wherein the prism sheet is arranged such that the light refracting surface extends to the left and right during use. 6. The liquid crystal display according to claim 1, wherein the prism sheet has a function of condensing light emitted from the illumination device on an observation side. apparatus. 7. A further prism sheet having a light refracting surface inclined in a direction different from the light refracting surface of the prism sheet is arranged on the side of the prism sheet facing the illuminating device. Item 7. The liquid crystal display device according to any one of items 1 to 6. 8. The liquid crystal display device according to claim 1, wherein the light scattering layer is a forward scattering layer that mainly causes forward scattering. 9. The liquid crystal display device according to claim 8, wherein the haze of the forward scattering layer is 60% or more. 10. The retardation value of the light scattering layer is 1
It is 0 nm or less, The liquid crystal display device of any one of Claim 1 thru | or 9 characterized by the above-mentioned. 11. The liquid crystal display device according to claim 1, wherein a reflective polarizing plate is arranged between the second polarizing plate and the lighting device. . 12. The liquid crystal display device according to claim 11, wherein a first retardation plate is arranged on the side opposite to the side where the liquid crystal cell is arranged with respect to the reflective polarizing plate. 13. The liquid crystal display device according to claim 12, wherein the first retardation plate includes at least a quarter-wave plate. 14. The liquid crystal display device according to claim 12, wherein the first retardation plate includes a quarter-wave plate and a half-wave plate. 15. The liquid crystal display device according to claim 12, wherein the retardation value of the first retardation plate is in the range of 100 nm to 180 nm. 16. The chromatic dispersion of the first retardation plate has a value of 1 or less, as claimed in claim 12.
5. The liquid crystal display device according to any one of item 5. 17. The liquid crystal display device according to claim 12, wherein the first retardation plate is arranged closer to the lighting device than the prism sheet is. . 18. The liquid crystal display device according to claim 1, wherein the reflection surface of the reflection plate is in a mirror surface state. 19. A second retardation plate is provided between the first polarizing plate and the first substrate or between the second polarizing plate and the second substrate. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device. 20. The transmission axis of the second polarizing plate and the transmission axis of the reflective polarizing plate are parallel to each other.
20. The liquid crystal display device according to claim 19. 21. The transmission axis of the second polarization plate and the transmission axis of the reflection polarization plate intersect each other in a plane, and an angle ψ formed by the transmission axis is in the range of 0 ° <ψ <10 °. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device. 22. The liquid crystal display device according to claim 1, wherein the display mode is a normally white mode. 23. The first polarizing plate and the second polarizing plate are absorption type polarizing plates.
23. The liquid crystal display device according to claim 22. 24. Any one of claims 1 to 23.
An electronic device comprising the liquid crystal display device according to item.