JP2002107706A - Liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide a liquid crystal display device excellent in display quality. SOLUTION: A pair of substrates 10 and 20, a liquid crystal layer 30 provided between the pair of substrates 10 and 20, a polarizing plate 15 provided on the viewer side of the liquid crystal layer 30, and a polarizing plate 1
5, a liquid crystal display comprising a plurality of pixels arranged in a matrix, comprising an anti-glare layer 16 provided on the viewer side, and a diffusion layer 14 provided between the liquid crystal layer 30 and the anti-glare layer 16. In the device, the diffusion layer 14 suppresses the occurrence of moire caused by the anti-glare layer 16 and the plurality of pixels.

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 more particularly to a liquid crystal display device having excellent display quality.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display device has been provided with OA equipment such as a word processor and a personal computer, portable information equipment such as an electronic organizer and a game machine, or a liquid crystal monitor by utilizing the characteristics of being thin and having low power consumption. Widely used in camera-integrated VTRs.

A liquid crystal display device is not a self-luminous display device that emits light by itself, unlike a CRT (cathode ray tube) or EL (electroluminescence) device. Therefore, a lighting device such as a fluorescent tube (so-called back light) is provided behind the liquid crystal panel. Light) and display using light incident from it (referred to as “transmission type”), or using a reflector instead of a backlight to display using ambient light (Referred to as “reflection type”).

Further, as a display device having both of the functions of the above-mentioned transmission type and reflection type and performing display using light from a backlight and / or ambient light, a transflective type and a transflective type (hereinafter, referred to as a transmissive type). There is proposed a liquid crystal display device of "double-purpose type").

For example, the transflective liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 7-333598 has a transflective film that reflects and transmits incident light at a certain reflectance and transmittance.

A dual-purpose liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. H11-101992 uses a reflection area for displaying in a reflection mode using external light for each display pixel and light from a backlight. And a transmission area for displaying a transmission mode.

As described above, liquid crystal display devices are roughly classified into a transmission type, a reflection type, a semi-transmission type, and a transmission / reflection type according to the way of using light. Have been.

However, in all of the above-described liquid crystal display devices, ambient light is specularly reflected (specular reflection) on the surface of the liquid crystal panel.
Accordingly, there is a problem that a surrounding image is reflected and visibility is reduced.

As means for solving this problem, an anti-glare layer called an anti-glare (AG) film is generally provided on the surface of the liquid crystal panel on the viewer side. The AG film is a transparent film having irregularities on the film surface, and diffusely reflects (scatters) light, so that the specular reflection of ambient light on the liquid crystal panel surface is suppressed, and the surrounding image is not reflected and visibility. However, a good display is realized. Most liquid crystal display devices currently in practical use include a polarizing plate for performing display in a polarization mode, and the AG film is often formed integrally with the surface of the polarizing plate.

[0010]

However, in recent years, when a liquid crystal display device is remarkably reduced in size and high definition, when an AG film is provided on a small and high definition liquid crystal display device, the reflection of an image of the surroundings is reduced. However, there is a problem that the display is rough, and this display defect becomes more remarkable as the ambient light becomes stronger, so that the display quality is degraded when the device is used outdoors under fine weather.

The inventor of the present application has made intensive studies to solve the above-mentioned problems. As a result, this display defect is caused by an AG film (anti-glare layer) having an uneven surface and a plurality of pixels arranged in a matrix. It was found that it was caused by the occurrence of moire. Moiré is caused by light interference generated when a plurality of periodic structures are superimposed.

Japanese Patent Application Laid-Open No. 9-258013 discloses a diffusion plate having an uneven surface for increasing the viewing angle without deteriorating the display quality of a liquid crystal display device. In a liquid crystal display device provided with a plate, there is a description that moiré fringes due to the diffusion plate and a color filter do not occur. However, there is no description that this diffusion plate suppresses the generation of moire caused by components other than the diffusion plate of the liquid crystal display device.
No mention is made of generation of moire by the G film and the plurality of pixels. Further, the inventor of the present application has confirmed that display roughness occurs in a small and high-definition liquid crystal display device provided with this diffusion plate.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display device having excellent display quality.

[0014]

A liquid crystal display device according to the present invention comprises a pair of substrates, a liquid crystal layer provided between the pair of substrates, and a polarizing plate provided on the viewer side of the liquid crystal layer. An anti-glare layer provided on the viewer side of the polarizing plate, and a diffusion layer provided between the liquid crystal layer and the anti-glare layer, comprising a plurality of pixels arranged in a matrix. In the liquid crystal display device, the diffusion layer suppresses the generation of moiré caused by the antiglare layer and the plurality of pixels, thereby achieving the above object.

[0015] The plurality of pixels may be arranged at a pitch of 120 µm or less.

It is preferable that the anti-glare layer has an uneven surface and is formed of a transparent material.

It is preferable that the diffusion layer is disposed between the liquid crystal layer and the polarizing plate.

[0018] The diffusion layer may be disposed between the polarizing plate and the antiglare layer.

The haze value of the diffusion layer is 20% or more and 70%
The following is preferred.

The total haze value of the diffusion layer and the antiglare layer is preferably 30% or more and 80% or less.

Preferably, the diffusion layer has a flat surface.

The distance between the diffusion layer and the liquid crystal layer is 0.1 mm.
It is preferable that it is 2 mm or more and 1.4 mm or less.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments. (Embodiment 1) FIG. 1 schematically shows a liquid crystal display device 100 according to Embodiment 1 of the present invention.

The liquid crystal display device 100 includes a color filter substrate 10, a TFT substrate 20, and a color filter substrate 10.
And a liquid crystal layer 30 provided between the TFT substrate 20 and a transmission type liquid crystal display device that performs display using light from a backlight 90 provided on the TFT substrate 20 side.

The color filter substrate 10 has a color filter 12 provided on the liquid crystal layer 30 side of a transparent substrate (eg, a glass substrate) 11 and a color filter 12 formed on the color filter 12 using a transparent conductive material (eg, ITO). Electrode 13
And a diffusion layer 14 provided on the viewer side of the transparent substrate 11.
And a polarizing plate 15 provided on the diffusion layer 14 and the polarizing plate 1
And an anti-glare layer 16 provided on the upper surface 5.

The TFT substrate 20 includes a source wiring provided on the liquid crystal layer 30 side of a transparent substrate (for example, a glass substrate) 21,
Gate wiring and TFT (both not shown), TFT
A pixel electrode (not shown) made of a transparent conductive layer (for example, an ITO layer) electrically connected to the drain electrode of FIG. 1, and a polarizing plate 22 provided on the backlight 90 side of the transparent substrate 21.

As the liquid crystal layer 30, a liquid crystal layer capable of displaying a polarization mode is used. For example, a TN (twisted nematic) mode liquid crystal layer is used.

The region where the opposing electrode 12 provided on the color filter substrate 10 and the pixel electrode provided on the TFT substrate 20 oppose each other defines a "pixel".
00 has a plurality of pixels arranged in a matrix. In the present embodiment, the pixel arrangement is a stripe arrangement as shown in FIG. 2, and the pixel pitch H in the horizontal direction (short direction of the pixel) is about 90 μm and the pixel pitch H in the vertical direction (longitudinal direction of the pixel) V is about 270 μm.

The anti-glare layer 16 provided on the observer side surface of the liquid crystal display device 100 is formed of a transparent material.
Since the surface has an uneven shape, external light (ambient light) incident mainly from the observer side is diffusely reflected (scattered). Therefore, the specular reflection of the ambient light on the surface of the liquid crystal display device 100 is suppressed, and as a result, a display with good visibility without surrounding image reflection is realized.

In a conventional liquid crystal display device, particularly a liquid crystal display device having a pixel pitch (either horizontal or vertical pitch) of 120 μm or less, an antiglare layer is provided to realize the above-described display. In such a case, there has been a problem that the display screen is rough. The inventor of the present application has found that this display defect is caused by moiré caused by an antiglare layer having an uneven shape and a plurality of pixels arranged in a matrix, and reached the present invention.

The diffusion layer 14 included in the liquid crystal display device 100 according to the present invention has a function of suppressing the occurrence of moire caused by the anti-glare layer 16 and a plurality of pixels arranged in a matrix. The display without the display is realized.

That is, the liquid crystal display device 100 according to the present invention
, The diffusion layer 1 between the liquid crystal layer 30 and the anti-glare layer 16
Since the light 4 is provided, the light that enters from the backlight 90 and passes through the liquid crystal layer 30 passes through the diffusion layer 14 before being emitted to the viewer side, and is scattered by the diffusion layer 14.
Accordingly, the occurrence of moire by the anti-glare layer 16 and the plurality of pixels arranged in a matrix is suppressed, and as a result, a display without roughness is realized.

The diffusion layer 14 is made of a material obtained by dispersing and mixing fine particles (for example, SiO ₂ ) having a refractive index different from that of the base material in a colorless and transparent base material (for example, acrylic resin). Preferably, it is formed. The average particle diameter of the fine particles is preferably in the range of about 0.5 μm to about 10 μm. If the average particle diameter is smaller than about 0.5 μm, a sufficient diffusion effect cannot be obtained. Since the entire layer 15 is thick, it is difficult to control the film thickness uniformly and control the distribution of fine particles. Addition amount of fine particles (weight)
May be appropriately set so as to obtain a desired diffusivity (haze value) in consideration of a difference in refractive index from a substrate, an average particle diameter, specific gravity, and the like.

The diffusion layer 14 may be formed as a thin film on the surface of another member (for example, a polarizing plate) or may be formed as a self-supporting film. In addition, a diffusion layer and an adhesive layer may be formed using a material having a diffusive property and an adhesive property. When the diffusion layer 14 is formed as both a diffusion layer and an adhesive layer, the thickness of the diffusion layer 14 is
It is preferable that the thickness be in the range of about 5 μm to about 50 μm from the viewpoint of ease of handling (handling properties) of the diffusion layer 14 and reworkability when a defect occurs. Further, the diffusion layer 14 preferably has a flat surface from the viewpoint of improving adhesion to layers or substrates disposed on both sides of the diffusion layer 14 and reducing backscattering. Further, the diffusion layer 14 may have photosensitivity, and may be appropriately patterned by a photolithography process or the like. However, from the viewpoint of workability and the like, it is preferable to provide it on almost the entire display surface, and it is also preferable to double as the adhesive layer.

The diffusion layer 14 has a function of scattering light as described above (hereinafter, referred to as “diffusion function”), and the diffusion function depends on the optical characteristics of the diffusion layer 14. One of the physical properties indicating the optical characteristics of the diffusion layer 14 is a haze value calculated by the following equation. The larger the haze value of the diffusion layer 14, the stronger the diffusion function. Haze value: H (%) = (diffuse transmittance / total light transmittance) · 100 In order to prevent the occurrence of moiré by the antiglare layer 16 and the plurality of pixels and to suppress the occurrence of display roughness, diffusion is required. It is necessary that the diffusion function of the layer 14 is sufficiently strong. However, if the diffusion function is too strong, a displayed image is blurred. By using the diffusion layer 14 having an appropriate diffusion function, that is, having an appropriate haze value, it is possible to realize high-quality display in which display roughness and blurring of a display image are suppressed.

Table 1 shows the results of visual evaluation of display roughness and image blur when the haze value of the diffusion layer 14 is changed in the liquid crystal display device 100. [Table 1] Haze value of diffusion layer (%) Roughness of display Image blur 15 × ◎ 20 ○ ◎ 30 ◎ ◎ 40 ◎ ◎ 50 ◎ ◎ 60 ◎ ○ 70 ◎ × The visual evaluation was performed under the following conditions. I went in. First,
The haze value of the diffusion layer 14 was measured using an integrating sphere type light transmittance measuring device (haze meter) according to JIS K7105. In addition, a type 2 color TFT-LCD module was used as a liquid crystal module, and AGT1 (hazing value: about 15%) manufactured by Nitto Denko Corporation was used as an antiglare layer 16.
The thickness of the transparent substrate 11 on the observer side of the above-mentioned module is about 0.7 mm, and the diffusion layer 14 is provided immediately above the transparent substrate 11 also as an adhesive layer between the transparent substrate 11 and the polarizing plate 15. Therefore, the distance between the liquid crystal layer 30 and the diffusion layer 14 is about 0.7 mm. The light source has a surface brightness of 5000c
A d / m ² mercury-based white backlight was used. In this visual evaluation, the haze value of the diffusion layer 14 was changed by changing the amount of the fine particles mixed with the base material. Then, small pictures and characters are displayed on the display screen, and the subjects are 30 men and women in their 20s to 50s who are randomly selected.

In addition, the criteria for visual evaluation relating to display roughness and image blur in Table 1 are as follows.

<Roughness of display> ：: 70% or more of the subjects “have little or no understanding of the roughness” ○: 40% or more of the subjects “have some roughness but do not mind” ×: 40% or more of the subjects have “roughness” Is clearly observed and cannot be tolerated as display quality. "<Image blur> ◎: 70% or more of the subjects are“ not at all concerned about image blur ”○: 40% or more of the subjects are“ very blurry of the image ” ×: 40% or more of the subjects “observed blurring of the image and cannot bear the display quality” As can be seen from Table 1, the haze value is about 20% or more and about 70%.
When a diffusion layer of not more than% is used, a high-quality display in which display roughness and image blurring are suppressed is realized.
In particular, when a diffusion layer having a haze value of about 30% or more and about 60% or less is used, higher-quality display with further suppressed display roughness and image blur is realized. When a diffusion layer having a haze value of less than about 20% is used, although blurring of an image does not occur, generation of moire by the antiglare layer and the plurality of pixels cannot be sufficiently suppressed, and display roughness occurs. If the haze value exceeds about 70%, the display is not rough, but the image is blurred because the diffusion function is too strong.

As described above, by using the diffusion layer 14 having an appropriate haze value, high-quality display is realized.

Although the optical characteristics of the diffusion layer 14 can be indicated by using the haze value as described above, the optical characteristics of the antiglare layer 16 can also be indicated by using the haze value. In No. 16, the larger the haze value, the stronger the function of diffusely reflecting (or scattering) ambient light.

In general, as the haze value of the anti-glare (AG) film used as the anti-glare layer 16 increases, the pitch (average peak-valley interval) of the irregularities on the surface decreases. For example, the pitch of an AG film having a haze value of 7% has a distribution of about 100 μm to about 150 μm on average, and the pitch of an AG film having a haze value of 25% has an average of about 40 μm.
It has a distribution from μm to about 50 μm. Therefore, when an AG film having a relatively large haze value is used as the anti-glare layer 16, the difference between the pitch of the uneven shape of the anti-glare layer 16 and the pixel pitch becomes large. The roughness of the display due to the occurrence of is relatively low.

Therefore, when an AG film having a relatively large haze value is used as the anti-glare layer 16, even if the diffusion layer 14 having a relatively small haze value (the diffusion function is relatively weak) is used, moiré is generated. Can be sufficiently suppressed. Also, on the contrary,
When an AG film having a relatively small haze value is used as the anti-glare layer 16, it is preferable to use the diffusion layer 14 having a relatively large haze value (having a relatively strong diffusion function).

Table 2 shows the results of visual evaluation of display roughness and image blur when the total haze value of the diffusion layer 14 and the antiglare layer 16 was changed. Also in this visual evaluation, AGT1 (haze value: about 15%) manufactured by Nitto Denko Corporation was used as the antiglare layer 16, and other experimental conditions and criteria were the same as the experimental conditions and criteria in Table 1. [Table 2] Total (%) of haze values of antiglare layer and diffusion layer Roughness of display Image blur 15 × ◎ 20 × ◎ 30 ○ ◎ 35 ◎ ◎ 45 ◎ ◎ 55 ◎ ◎ 65 ◎ ◎ 75 ◎ ○ 80 ◎ ○ 85 ◎ × As can be seen from Table 2, when the total haze value of the diffusion layer 14 and the antiglare layer 16 is about 30% or more and about 80% or less,
A high-quality display in which display roughness and image blurring are suppressed is realized. In particular, the total haze value is about 3
When it is 5% or more and about 65% or less, higher quality display is realized, in which the occurrence of display roughness and image blur is further suppressed. If the total haze value is less than about 30%, the image will not be blurred, but the occurrence of moiré due to the antiglare layer 16 and the plurality of pixels cannot be sufficiently suppressed, resulting in display roughness. Also, the total haze value is about 80%
If it exceeds, the display will not be rough, but the image will be blurred because the diffusion function is too strong.

As described above, by using the diffusion layer 14 having an appropriate haze value according to the antiglare layer 16 to be used, a high-quality display is realized. However, the haze value of the antiglare layer 16 provided on the outermost surface of the liquid crystal display device and having irregularities on the surface is preferably in the range of about 5% to about 30%, and is preferably in the range of about 7% to about 25%. It is more preferred that there be. If the haze value of the anti-glare layer 16 is less than about 5%, the reflection of surrounding images cannot be sufficiently suppressed, and if it exceeds about 30%, the displayed image is blurred. The haze value is about 30.
%, The reflection on the surface of the anti-glare layer 16 becomes large, and the screen becomes white and the contrast ratio is lowered.

The sum of the haze values of the diffusion layer 14 and the anti-glare layer 16 is a haze value measured in an arrangement where light continuously passes through the diffusion layer 14 and the anti-glare layer 16. This value is slightly smaller than the sum of the haze values measured individually for the diffusion layer 14 and the antiglare layer 16. The sum of the haze values in Table 2 is a haze value measured for the arrangement of the diffusion layer 14 / the polarizing plate 15 / the anti-glare layer 16, and is a simple value of the respective haze values of the diffusion layer 14 and the anti-glare layer 16. The sum (arithmetic sum) is about 5% to about 10% larger than the haze value. For example, 20% and 30% shown as the sum of the haze values in Table 2 are about 25% and about 35%, respectively, as a simple sum of the individual haze values.

The distance between the diffusion layer 14 and the liquid crystal layer 30 also has a great effect on suppressing the occurrence of moire. Table 3 shows that when the distance between the diffusion layer 14 and the liquid crystal layer 30 was changed,
The result of performing a visual evaluation on display roughness and image blur is shown. In this visual evaluation, a diffusion layer 14 having a haze value of about 50% and an antiglare layer 16 having a haze value of about 15% were used. The diffusion layer 14 and the liquid crystal layer 30
(In the present embodiment, the color filter 12
(The distance between the black matrix (not shown) and the diffusion layer 14) was changed by adjusting the thickness of the transparent substrate 11. The diffusion layer 14 was disposed between the transparent substrate 11 and the polarizing plate 15 as in the visual evaluation in Table 1. However,
When the distance was about 0 mm, it was arranged between the transparent substrate 11 and the color filter 12. Other experimental conditions and criteria are the same as the experimental conditions and criteria in Table 1.

In this embodiment, the diffusion layer 14
Was arranged on the viewer side of the transparent substrate 11 and the distance between the liquid crystal layer 30 and the diffusion layer 14 was changed by changing the thickness of the transparent substrate 11. The liquid crystal layer 30 may be disposed on the
It is possible to change the distance between and the diffusion layer 14. [Table 3] Distance between diffusion layer and liquid crystal layer (mm) Roughness of display Image blur 0 × ◎ 0.2 ○ ◎ 0.4 ◎ ◎ 0.5 ◎ ◎ 0.7 ◎ ◎ 1.1 ◎ ◎ １ 1.4 ◎ 1.6 ◎ × As can be seen from Table 3, when the distance between the diffusion layer 14 and the liquid crystal layer 30 is not less than about 0.2 mm and not more than about 1.4 mm, display roughness and image blurring occur. , And a high-quality display is realized. In particular, when the distance between the diffusion layer 14 and the liquid crystal layer 30 is about 0.4 mm or more and about 1.1 mm or less,
A higher-quality display in which the occurrence of display roughness and image blur is further suppressed is realized. If the distance between the diffusion layer 14 and the liquid crystal layer 30 is less than about 0.2 mm, the image is not blurred, but the occurrence of moiré due to the antiglare layer 16 and the plurality of pixels cannot be sufficiently suppressed, and Roughness occurs. Further, when the distance between the diffusion layer 14 and the liquid crystal layer 30 exceeds about 1.4 mm, the display is not rough, but the diffusion function is too strong (or the parallax becomes large), and the image is blurred.

As described above, by arranging the diffusion layer 14 and the liquid crystal layer 30 such that the distance between the diffusion layer 14 and the liquid crystal layer 30 is an appropriate distance, a high quality display is realized.

In the liquid crystal display device 100 of the present invention,
Since the diffusion layer 14 is disposed between the liquid crystal layer 30 and the polarizing plate 15, it is easy to adopt a configuration in which the distance between the liquid crystal layer 30 and the diffusion layer 14 is relatively short. Therefore, the occurrence of image blur can be more easily suppressed.

As described above, the diffusion layer 14 serves as the liquid crystal layer 3.
Since the light is disposed between the zero and the polarizing plate 15, part of the incident light is absorbed by the polarizing plate when the ambient light reaches the diffusion layer 14. The backscattered light generated in the diffusion layer 14 also passes through the polarizing plate when emitted, so that backscattered light is considerably reduced. Therefore, display with a high contrast ratio is realized by suppressing backscattering.

In this embodiment, the case where the pixel arrangement is a stripe arrangement as shown in FIG. 2 has been described. Of course, the pixel arrangement may be a delta arrangement as shown in FIG. Is not limited to the value of the present embodiment.

In this embodiment, the case where the diffusion layer 14 is disposed between the liquid crystal layer 30 and the polarizing plate 15 as shown in FIG. 1 has been described. However, as shown in FIG. The diffusion layer 14 may be arranged between the polarizing plate 15 and the anti-glare layer 16. With such a configuration,
Since the diffusion layer 14 is provided closer to the viewer than the polarizing plate 15, light incident from the backlight and transmitted through the liquid crystal layer 30 disturbs the polarization plane by the diffusion layer 14 before entering the polarizing plate 15. Never be. Therefore, light leakage in the black display state is suppressed, and as a result, display with a high contrast ratio is realized.

Further, the diffusion layer 14 may also serve as an adhesive layer for bonding the polarizing plate 15 and the transparent substrate 11 (or may be included in the adhesive layer). Needless to say, an adhesive layer may be provided separately from the diffusion layer 14, or the diffusion layer 14 formed as a film may be integrated with the polarizing plate 15.
Further, the transparent layer 11 provided on the viewer side is provided with the diffusion layer 1.
The one having the function as 4 may be used. (Embodiment 2) FIG. 5 schematically shows a liquid crystal display device 200 according to Embodiment 2 of the present invention. In the following drawings, components having substantially the same function are denoted by the same reference numerals.

The liquid crystal display device 200 includes a color filter substrate 10, a TFT substrate 20, and a color filter substrate 10.
And a liquid crystal layer 30 provided between the TFT substrate 20 and a transflective liquid crystal for performing display using light from a backlight 90 and / or ambient light provided on the TFT substrate 20 side. A display device.

The color filter substrate 10 includes a liquid crystal layer 3 of a transparent substrate (for example, a glass substrate having a thickness of about 0.7 mm).
A color filter 12 provided on the zero side, a counter electrode 13 formed on the color filter 12 using a transparent conductive material (for example, ITO), and a diffusion layer 14 provided on the viewer side of the transparent substrate 11. It has a polarizing plate 15 provided on the diffusion layer 14 and an antiglare layer 16 provided on the polarizing plate 15.

The TFT substrate 20 includes a polarizing plate 22 provided on the backlight side of a transparent substrate (eg, a glass substrate) 21.
A source line, a gate line, and a TFT (not shown) provided on the liquid crystal layer 30 side of the transparent substrate 21;
Pixel electrode 23 electrically connected to the drain electrode of FT
And

As shown in FIGS. 5 and 6, the pixel electrode 23 is formed by using a transparent electrode 24 formed by using a transparent conductive material (eg, ITO) and a metal having a high reflectivity (eg, Al). And the reflective electrode 25,
The reflection electrode 25 has an uneven shape on the surface, and also functions as a diffuse reflection layer. By using the light diffusely reflected on the uneven surface of the reflection electrode 25, a paper white reflection mode display is realized. Further, the thickness of the liquid crystal layer 30 above the reflective electrode 25 is greater than the thickness of the liquid crystal layer 30 above the transparent electrode 24.
The interlayer insulating film 26 below the reflective electrode 25 is formed to be thicker than the interlayer insulating film (not shown) below the transparent electrode 24 so that the thickness of the interlayer insulating film 26 becomes approximately の of the thickness of the transparent electrode 24.

As the liquid crystal layer 30, a liquid crystal layer capable of displaying a polarization mode is used. For example, a liquid crystal layer capable of displaying a TN (twisted nematic) mode or an ECB mode is used.

The area where the opposing electrode 12 provided on the color filter substrate 10 and the pixel electrode 23 provided on the TFT substrate 20 oppose each other defines a pixel.
00 has a plurality of pixels arranged in a matrix. In this embodiment, the pixel arrangement is a stripe arrangement, and the pixel pitch in the horizontal direction (short direction of the pixel) is about 72.5 μm, and the pixel pitch in the vertical direction (longitudinal direction of the pixel) is about 138.5 μm. is there. The length of the transparent electrode 24 in the horizontal direction is about 38 μm, the length in the vertical direction is about 82 μm, and the area ratio between the transparent electrode 24 and the reflective electrode 25 is about 6:
4. Further, the transparent electrode 24 is provided at the center of the pixel.

The anti-glare layer 16 provided on the observer side surface of the liquid crystal display device 200 is formed of a transparent material.
Since the surface has an uneven shape, light is diffusely reflected (scattered). Therefore, specular reflection on the surface of the liquid crystal display device 200 is suppressed, and as a result, a display with no visibility and good visibility is realized.

A conventional liquid crystal display device, in particular, a pixel pitch of 1
In a liquid crystal display device having a size of 20 μm or less, when an antiglare layer is provided in order to realize the above-described display, there is a problem that the display screen is rough. In particular, in a transmissive / reflective liquid crystal display device in which a reflective portion for reflecting external light and a transmissive portion for transmitting light from a backlight are formed for each pixel, this display defect becomes more remarkable. The reason will be described below.

In a transflective liquid crystal display device,
Since a transmission portion and a reflection portion are formed for each pixel, a plurality of pixels are arranged in a periodic pattern, and a plurality of transmission portions (transparent electrodes) and a plurality of reflection portions (reflection electrodes) are also provided. They are arranged in a periodic pattern. Therefore, moire due to the anti-glare layer, the plurality of pixels, the plurality of transmission portions and the plurality of reflection portions occurs, and as a result,
It is considered that the display failure is remarkable. In addition, the fact that the pitch of the periodic structure formed by the transmissive portion and the reflective portion is smaller than the pixel pitch is also considered to be a factor that makes display defects noticeable.

The diffusion layer 14 included in the liquid crystal display device 200 according to the present invention has a function of suppressing the occurrence of the above-described moiré, thereby realizing a display without roughness.

That is, in the transflective liquid crystal display device 200 according to the present invention, the liquid crystal layer 30 and the anti-glare layer 16
Is provided between the light source and the light source, the light incident from the backlight 90 and transmitted through the liquid crystal layer 30 and the light incident from the viewer side and reflected by the reflective electrode 25 and transmitted through the liquid crystal layer 30. The light passes through the diffusion layer 14 before being emitted to the observer side, and is scattered by the diffusion layer 14. Accordingly, moire caused by the anti-glare layer 16 and a plurality of pixels, the anti-glare layer 1
6 and a plurality of transmissive parts, moire and anti-glare layer 16
The generation of moiré due to and the plurality of reflection portions is suppressed, and as a result, a display without roughness is realized.

In the liquid crystal display device 200, the diffusion layer 1
Reference numeral 4 is formed using a light-scattering material having an adhesive property (for example, a diffuser manufactured by Nitto Denko Corporation), and also functions as an adhesive layer for bonding the transparent substrate 11 and the polarizing plate 15. When the diffusion layer 14 is formed to a thickness of about 30 μm using the above-described material, the haze value of the diffusion layer 14 is about 35%.

Table 4 shows the results of visual evaluation of display roughness and image blur when the haze value of the diffusion layer 14 is changed in the liquid crystal display device 200. Table 4
Are the same as those in Table 1 except for the light source used. In a dual-purpose liquid crystal display device,
Visual evaluation of both display in the transmission mode and display in the reflection mode is required, but roughness in the transmission mode is more likely to be noticeable in moire than in the reflection mode. Therefore,
Here, the reflection mode was visually evaluated. As a light source for external light (ambient light), it simulates sunlight and
In order to keep the light source constant, a light source box capable of obtaining an illuminance of 50,000 lux was prepared and used. Table 4 below shows the results of the visual evaluation in the reflection mode. When the visual evaluation in the transmission mode was also performed, similar results were obtained. In the visual evaluation in the transmission mode, the mercury-based white backlight used in the visual evaluation in Table 1 was used. [Table 4] Haze value (%) of diffusion layer Roughness of display Image blur 15 × ◎ 20 × ◎ 30 ◎ ◎ 40 ◎ ◎ 50 ◎ ○ 60 ◎ ○ 70 ◎ × 80 ◎ × The value is about 30% or more and about 60
When a diffusion layer of not more than% is used, a high-quality display in which display roughness and image blurring are suppressed is realized.

In the above-mentioned visual evaluation, an AG film having a haze value of about 15% was used as the antiglare layer 16, but an AG film having a larger haze value (for example, a haze value of about 25%) was used.
% Of AGS1) manufactured by Nitto Denko Corporation, the diffusion layer 14 has a relatively weak diffusion function (has a relatively small haze value).
Is used, moire caused by the anti-glare layer 16 and the plurality of pixels can be sufficiently suppressed. Further, an AG film having a smaller haze value (for example, an AG film having a haze value of about 7% manufactured by Nitto Denko Corporation)
When 30) is used, it is preferable to use the diffusion layer 14 having a relatively strong diffusion function (having a relatively large haze value).

In the present embodiment, the case where the area ratio between the reflective electrode and the transparent electrode is about 6: 4 has been described. However, the present invention is not limited to this, and as shown in FIGS. 7 (a) and 7 (b). Any area ratio may be used.

The inventor of the present application has described the above-described liquid crystal display device 200.
, The transmissive portion (transparent electrode) is smaller, for example, the horizontal length of the transparent electrode is about 31 μm, the vertical length is about 45 μm, and the area ratio between the reflective electrode and the transparent electrode is about 9:
It has been experimentally confirmed that when set to 1, the display failure becomes more remarkable. Therefore, when the size of the transmission part is set as described above, it is preferable to use the diffusion layer 14 having a relatively strong diffusion function (having a relatively large haze value).

Table 5 shows the results of visual evaluation of display roughness and image blur when the haze value of the diffusion layer 14 is changed in the liquid crystal display device 200 in which the transmission portion is set as described above. The experimental conditions and criteria for visual evaluation in Table 5 are the same as the experimental conditions and criteria for visual evaluation in Table 4. [Table 5] Haze value (%) of diffusion layer Roughness of display Image blur 15 × ◎ 20 × ◎ 30 × ◎ 40 ◎ ◎ 50 ◎ ◎ 60 ◎ ◎ 70 ◎ × 80 ◎ × As can be seen from Table 5, transmission. When the portions are set as described above, the use of a diffusion layer having a haze value of about 40% or more and about 60% or less realizes high-quality display in which display roughness and image blur are suppressed.

In this embodiment, the case where the arrangement of the pixels is a stripe arrangement has been described, but of course, the arrangement may be a delta arrangement, and the value of the pixel pitch is not limited to the value of this embodiment. In addition, the transmitting portion may be provided at a position other than the central portion of the pixel, and a plurality of transmitting portions may be provided.

Further, a retardation plate may be provided between the transparent substrate 11 and the polarizing plate 15, and the transparent substrate 11, the adhesive layer, the retardation plate, the adhesive layer, and the polarizing plate 15 are laminated in this order. At least one of the adhesive layers may be the diffusion layer 14 functioning as an adhesive layer.

Further, in this embodiment, the diffusion layer 1
Although the case where No. 4 also functions as an adhesive layer has been described,
Of course, it may not function as an adhesive layer. (Embodiment 3) FIG. 8 schematically shows a liquid crystal display device 300 according to Embodiment 3 of the present invention.

The liquid crystal display device 300 includes a color filter substrate 10, a TFT substrate 20, and a color filter substrate 10.
And a liquid crystal layer 30 provided between the TFT substrate 20 and a reflective liquid crystal display device that performs display using ambient light.

The color filter substrate 10 has a color filter 12 provided on the liquid crystal layer 30 side of a transparent substrate (eg, a glass substrate) 11 and a color filter 12 formed on the color filter 12 using a transparent conductive material (eg, ITO). Electrode 13
And a diffusion layer 14 provided on the viewer side of the transparent substrate 11.
And a polarizing plate 15 provided on the diffusion layer 14 and the polarizing plate 1
And an anti-glare layer 16 provided on the upper surface 5.

The TFT substrate 20 includes a source wiring provided on the liquid crystal layer 30 side of a transparent substrate (for example, a glass substrate) 21,
Gate wiring and TFT (both not shown), TFT
And a pixel electrode (reflection electrode; not shown) made of a high-reflectance metal layer (for example, an Al layer) electrically connected to the drain electrode. The pixel electrode has an uneven surface and has a diffuse reflection characteristic.

As the liquid crystal layer 30, a liquid crystal layer capable of displaying a polarization mode is used. For example, a TN (twisted nematic) mode liquid crystal layer is used.

The region where the counter electrode 12 provided on the color filter substrate 10 and the pixel electrode 23 provided on the TFT substrate 20 face each other defines a pixel.
00 has a plurality of pixels arranged in a matrix. In the present embodiment, the pixel arrangement is a stripe arrangement, and the pixel pitch in the horizontal direction (short direction of the pixel) is about 90 μm, and the pixel pitch in the vertical direction (longitudinal direction of the pixel) is about 270 μm.

The diffusion layer 14 included in the liquid crystal display device 300 according to the present invention has a function of suppressing the occurrence of moire caused by the anti-glare layer 16 and a plurality of pixels arranged in a matrix. The display without the display is realized.

That is, the liquid crystal display device 300 according to the present invention
, The diffusion layer 1 between the liquid crystal layer 30 and the anti-glare layer 16
4, the light that enters from the observer side, is reflected by the reflective electrode, and passes through the liquid crystal layer 30 passes through the diffusion layer 14 before exiting to the observer side, and is scattered by the diffusion layer 14. Is done. Therefore, the occurrence of moire by the anti-glare layer 16 and the plurality of pixels arranged in a matrix is suppressed. As a result, similar to the liquid crystal display devices 100 and 200, a display without roughness is realized.

Table 6 shows the results of visual evaluation of display roughness and image blur when the haze value of the diffusion layer 14 is changed in the liquid crystal display device 300. Table 6
In the visual evaluation in, a light source box for reproducing the sunlight used in the visual evaluation in Table 4 was used as a light source.
Other experimental conditions and criteria are the same as the visual evaluation in Table 1. [Table 6] Haze value (%) of diffusion layer Roughness of display Image blur 15 × ◎ 20 × ◎ 30 ○ ◎ 40 ◎ ◎ 50 ◎ ◎ 60 ◎ ◎ 70 ◎ × 80 ◎ × As can be seen from Table 6, haze The value is about 30% or more and about 60
When a diffusion layer of not more than% is used, a high-quality display in which display roughness and image blurring are suppressed is realized. (Embodiment 4) FIG. 9 schematically shows a liquid crystal display device 400 according to Embodiment 4 of the present invention.

The liquid crystal display device 400 includes a color filter substrate 10, a TFT substrate 20, and a color filter substrate 10.
And a liquid crystal layer 30 provided between the TFT substrate 20 and a reflective liquid crystal display device that performs display using ambient light.

This liquid crystal display device 400 has a TFT substrate 2
It has the same configuration as the liquid crystal display device 300 of the third embodiment except that the surface of the reflective electrode 25 provided on the zero is a mirror surface formed substantially flat.

The diffusion layer 14 included in the liquid crystal display device 400 according to the present invention has a function of suppressing the occurrence of moire caused by the anti-glare layer 16 and a plurality of pixels arranged in a matrix, thereby providing a rough surface. The display without the display is realized.

That is, the liquid crystal display device 400 according to the present invention
, The diffusion layer 1 between the liquid crystal layer 30 and the anti-glare layer 16
4, the light incident from the observer side, reflected by the reflective electrode 25, and transmitted through the liquid crystal layer 30 is:
The light passes through the diffusion layer 14 before being emitted to the observer side,
4 scattered. Therefore, the occurrence of moire by the anti-glare layer 16 and the plurality of pixels arranged in a matrix is suppressed. As a result, similar to the liquid crystal display devices 100, 200, and 300, a display without roughness is realized.

Table 7 shows the results of visual evaluation of display roughness and image blur when the haze value of the diffusion layer 14 is changed in the liquid crystal display device 400. Table 7
The experimental conditions and criteria for the visual evaluation in are the same as the visual evaluation in Table 6. [Table 7] Haze value of diffusion layer (%) Roughness of display Image blur 15 × ◎ 20 × ◎ 30 ○ ◎ 40 ◎ ◎ 50 ◎ ◎ 60 ◎ ◎ 70 ◎ × 80 ◎ × As can be seen from Table 7, haze The value is about 30% or more and about 60
When a diffusion layer of not more than% is used, a high-quality display in which display roughness and image blurring are suppressed is realized.

In the above-mentioned visual evaluation, an AG film having a haze value of about 15% was used as the antiglare layer 16, but an AG film having a larger haze value (for example, a haze value of about 25%) was used.
% Of the AG film), even when the diffusion layer 14 having a relatively small haze value (relatively weak diffusion function) is used, moire caused by the antiglare layer 16 and the plurality of pixels can be sufficiently suppressed. When an AG film having a smaller haze value (for example, an AG film having a haze value of about 7%) is used, the diffusion layer 14 having a relatively large haze value (having a relatively strong diffusion function) may be used. preferable. (Embodiment 5) FIG. 10 schematically shows a liquid crystal display device 500 according to Embodiment 5 of the present invention.

The liquid crystal display device 500 includes a color filter substrate 10, a TFT substrate 20, and a color filter substrate 10.
And a liquid crystal layer 30 provided between the TFT substrate 20 and a transflective liquid crystal for performing display using light from a backlight 90 and / or ambient light provided on the TFT substrate 20 side. A display device.

This liquid crystal display device 500 has a TFT substrate 2
The liquid crystal display device 200 has the same configuration as the liquid crystal display device 200 of the second embodiment except that the surface of the reflective electrode 25 provided on the zero is a mirror surface formed substantially flat.

The diffusion layer 14 included in the liquid crystal display device 500 according to the present invention has a function of suppressing the occurrence of moire caused by the anti-glare layer 16 and a plurality of pixels arranged in a matrix, thereby providing a rough surface. The display without the display is realized.

That is, the liquid crystal display device 500 according to the present invention
, The diffusion layer 1 between the liquid crystal layer 30 and the anti-glare layer 16
4, the light incident from the backlight 90 and transmitted through the liquid crystal layer 30 and the light incident from the observer side and reflected by the reflective electrode 25 and transmitted through the liquid crystal layer 30 are different from those of the observer. The light passes through the diffusion layer 14 before being emitted to the side, and is scattered by the diffusion layer 14. Therefore, the occurrence of moire by the anti-glare layer 16 and the plurality of pixels is suppressed. As a result, the liquid crystal display devices 100, 200, 300 and 400
In this way, a display without roughness is realized.

Table 8 shows the results of visual evaluation of display roughness and image blur when the haze value of the diffusion layer 14 is changed in the liquid crystal display device 500. Table 8
The experimental conditions and criteria for the visual evaluation in are the same as the visual evaluation in Table 4. The area ratio between the transmission part and the reflection part is about 6: 4. [Table 8] Haze value (%) of diffusion layer Roughness of display Image blur 15 × ◎ 20 ○ ◎ 30 ◎ ◎ 40 ◎ ◎ 50 ◎ ◎ 60 ◎ ○ 70 ◎ × 80 ◎ × As can be seen from Table 8, haze Value is about 20% or more and about 60
The use of a diffusion layer of not more than% realizes high-quality display in which display roughness and image blurring are suppressed.

In the above-mentioned visual evaluation, an AG film having a haze value of about 15% was used as the antiglare layer 16, but an AG film having a larger haze value (for example, a haze value of about 25%) was used.
% Of the AG film), the moire caused by the anti-glare layer 16 and the plurality of pixels can be sufficiently suppressed even if the diffusion layer 14 having a relatively small haze value (relatively weak diffusion function) is used. When an AG film having a smaller haze value (for example, an AG film having a haze value of about 7%) is used, the diffusion layer 14 having a relatively large haze value (having a relatively strong diffusion function) may be used. preferable.

[0094]

According to the present invention, the occurrence of moire by the antiglare layer and the plurality of pixels is suppressed, and a liquid crystal display device having excellent display quality is provided. In particular, the pixel pitch is 120 μm
A remarkable effect is exhibited in a high-definition liquid crystal display device having a resolution of about or less.

The present invention can be suitably used for any of a transmission type, a reflection type, a transflective type and a transmission / reflection type liquid crystal display device, and particularly to a liquid crystal display device used in an environment where ambient light is strong. It is preferably used.

[Brief description of the drawings]

FIG. 1 is a liquid crystal display device 100 according to a first embodiment of the present invention.
It is sectional drawing which shows typically.

FIG. 2 is a liquid crystal display device 100 according to a first embodiment of the present invention.
FIG. 3 is a diagram schematically showing an arrangement of pixels.

FIG. 3 is a liquid crystal display device 100 according to a first embodiment of the present invention.
FIG. 6 is a diagram schematically showing another arrangement of the pixel of FIG.

FIG. 4 is a liquid crystal display device 100 according to a first embodiment of the present invention.
FIG. 9 is a cross-sectional view schematically illustrating another configuration of the color filter substrate 10 included in the color filter substrate 10.

FIG. 5 is a liquid crystal display device 200 according to a second embodiment of the present invention.
It is sectional drawing which shows typically.

FIG. 6 shows a liquid crystal display device 200 according to a second embodiment of the present invention.
FIG. 3 is a diagram schematically showing a pixel electrode 23 included in the image forming apparatus.

FIG. 7 is a liquid crystal display device 200 according to a second embodiment of the present invention.
FIG. 4 is a diagram schematically showing another configuration of the pixel electrode 23 included in the pixel electrode 23.

FIG. 8 is a liquid crystal display device 300 according to a third embodiment of the present invention.
It is sectional drawing which shows typically.

FIG. 9 is a liquid crystal display device 400 according to a fourth embodiment of the present invention.
It is sectional drawing which shows typically.

FIG. 10 is a liquid crystal display device 50 according to a fifth embodiment of the present invention.
FIG.

[Explanation of symbols]

2 gate wiring 3 source wiring 4 TFT 5 connection electrode 6 contact hole 7 gate electrode 8 auxiliary capacitance electrode 9 gate insulating film 10 color filter substrate 11 transparent substrate 12 color filter 13 counter electrode 14 diffusion layer 15 polarizing plate 16 antiglare layer 20 TFT Substrate 21 Transparent substrate 22 Polarizer 23 Pixel electrode 24 Transparent electrode 25 Reflective electrode 26 Interlayer insulating film 30 Liquid crystal layer 100, 200, 300, 400, 500 Liquid crystal display

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoji Yoshimura 22-22, Nagaikecho, Abeno-ku, Osaka, Osaka F-term (reference) 2H042 BA02 BA03 BA12 BA20 2H049 BA02 BB63 2H091 FA08X FA08Z FA23Z FA31X FA31Z FA37X FA41Z LA16 5G435 AA01 BB12 CC09 EE25 FF05 FF06 HH03 HH04

Claims (9)

[Claims] 1. A pair of substrates, a liquid crystal layer provided between the pair of substrates, a polarizing plate provided on a viewer side of the liquid crystal layer, and a polarizing plate provided on a viewer side of the polarizing plate. An antiglare layer, a diffusion layer provided between the liquid crystal layer and the antiglare layer,
A liquid crystal display device comprising: a plurality of pixels arranged in a matrix, wherein the diffusion layer suppresses generation of moire by the antiglare layer and the plurality of pixels. 2. The liquid crystal display device according to claim 1, wherein the plurality of pixels are arranged at a pitch of 120 μm or less. 3. The liquid crystal display device according to claim 1, wherein the anti-glare layer has an uneven shape on the surface and is formed of a transparent material. 4. The liquid crystal display device according to claim 1, wherein said diffusion layer is disposed between said liquid crystal layer and said polarizing plate. 5. The liquid crystal display according to claim 1, wherein the diffusion layer is disposed between the polarizing plate and the anti-glare layer. 6. The haze value of the diffusion layer is 20% or more and 70% or more.
The liquid crystal display device according to any one of claims 1 to 5, wherein the content is not more than%. 7. The liquid crystal display device according to claim 1, wherein the total haze value of the diffusion layer and the antiglare layer is 30% or more and 80% or less. 8. The liquid crystal display device according to claim 1, wherein said diffusion layer has a flat surface. 9. The distance between the diffusion layer and the liquid crystal layer is:
9. The liquid crystal display device according to claim 1, which is not less than 0.2 mm and not more than 1.4 mm.