JP2007248803A - Liquid crystal image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress grayscale variations and color variation related to a viewing angle, while suppressing lowering of the luminance, lowering of contrast, and blurring in a liquid crystal display device, in particular, in a vertically aligned mode liquid crystal television. <P>SOLUTION: In a liquid crystal image display device which is constituted by applying a light-scattering film, having particulate regions (inner surface scattering body) with a diameter size of 0.1-0.5 μm, and with mutually different refractive indexes more intensely scattering (Mie scattering) light of the visible ray wavelength region, corresponding to the particle diameters in combination with a polarizing film to a liquid crystal display element, and which defines a display image with a vertically aligned mode or a twisted nematic (TN) aligned mode liquid crystal display element, equipped with the light-scattering film on the observer's side of the polarizing plate of the observer's side, when it is observed within the range of (-45°)-(+45°) with respect to a screen normal, fluctuation of γ is 0.5 or smaller, and the fluctuations in the luminance when input luminance signal value is 50% of the full range is 40% or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a color-correctable diffuser that can suppress a decrease in luminance of a liquid crystal display device by diffusing light and can form a liquid crystal display device with little color change depending on the viewing angle, and is particularly vertically aligned. When used with a liquid crystal cell, it compensates for color changes due to changes in gamma characteristics when the liquid crystal display is viewed from an oblique direction, scatters light on the short wavelength side more strongly, and has high parallel light transmittance and high backscattering. The present invention relates to a diffuser having a small scattering angle (Mie scattering), and further to a polarizing element using this diffuser, and applying this, there is little blur, high contrast, bright, gradation change, color The present invention relates to a liquid crystal display device with little change, and more particularly to a liquid crystal image display device such as a liquid crystal television that can easily view high-quality images.

Conventionally, CRT video display devices have been used for viewing video.
However, in order to use at home, a certain amount of installation area is required due to restrictions on weight and thickness, and the installation location is limited.

For this reason, flat panel displays that are light in weight and thin have been used in recent years.
Since flat panel displays such as liquid crystal display devices are light and thin, they have been widely used in mobile phones, personal computer monitors, notebook PCs, FAs, car navigation systems, and the like.
These mobile phone monitors and personal computer monitors mainly consist of character information, so there was little need for a clear halftone.
However, in recent years, liquid crystal display devices have been widely used as video display devices, liquid crystal televisions, or photo viewers.
In such a television, since not only text information but also images with many intermediate gradations such as images of human faces and landscapes are viewed from various angles, the image can be viewed from any angle. It is required that the impression does not change.

  In order to satisfy the above conditions as a liquid crystal system, liquid crystal of a system using various orientations such as a TN system, an OCB system, a VA system, and an IPS system has been invented so far. (Reference 1)

<TN method>
Among them, the TN liquid crystal display has a liquid crystal aligned to be twisted about 90 degrees, the charge direction is vertical, the transmittance is high, and the liquid crystal material itself is also horizontally aligned with a chiral agent mixed. It can be manufactured relatively inexpensively and easily.
In addition, the response is relatively high, and in recent years, products that are less than 10 msec have been commercialized.
However, even when the polarization is corrected in the retardation film, tone reversal occurs in the dark part, and there is a drawback that there is an observation angle that gives an impression that the negative of the photographic film is seen.

<OCB method>
In the TN mode, the liquid crystal is oriented by twisting by 90 °. On the other hand, there is an OCB mode in which the orientation is twisted by 180 °.
In this method, by using phase difference compensation, the color change due to the viewing angle is small, and gradation inversion is also eliminated.
Some responsiveness is less than 5 msec, which is higher than TN type.
However, since it has two stable states of bent orientation and splay orientation, it is difficult to produce a stable operation.
Further, although it is difficult to cause a decrease in luminance in the left-right direction, it tends to cause a decrease in luminance due to a decrease in transmittance in the vertical direction, and it seems that the vertical viewing angle is narrow.

<IPS method>
In the IPS-type liquid crystal display, the liquid crystal is aligned horizontally in the plane without twisting.
IPS has little change in gradation characteristics when observed from the front and when observed from an angle, and there are also little changes in hue and saturation.
Due to problems such as coloring, it is necessary to use a multi-domain, and it is necessary to form an electrode pattern only on one side of the glass. Since it is complicated, the aperture ratio is likely to decrease, and the electrode is difficult to form.
Moreover, although high responsiveness has been obtained in recent years, it is difficult to increase the responsiveness and the video tends to have a tail.
Although the transmittance of the liquid crystal is small regardless of the angle, the backlight unit light is high in the front direction and relatively low in the oblique direction, so viewing the video at an angle with respect to the screen normal The video looks dark, and the skin of a light-skinned female skin feels like sunburned skin.
In order to improve this, it is necessary to increase the luminance of light emitted obliquely from the backlight unit. However, if this is increased, the brightness of the backlight unit must be particularly increased.

<VA method>
Similarly, in order to solve the problem of the viewing zone, a VA liquid crystal display is known.
This liquid crystal is aligned vertically while the TN method and IPS method are aligned horizontally.
Even in this orientation, the gradation characteristics greatly change depending on the observation angle, so it is necessary to use a multi-domain.
This makes it difficult for inversion to occur, but when observed at an angle with respect to the screen normal, the gamma decreased by about 1.0 compared to when viewed from the front, and the image was blurred white. As a result, the skin color of a light-skinned female is negatively affected.
This is a characteristic that depends on the orientation itself, and it is very difficult to improve it by the cell itself.
In order to improve this point, there is a method of dividing a pixel further to produce a gradation, but the change in gradation characteristics is not sufficiently suppressed.
Furthermore, it is necessary to perform pixel division corresponding to the above viewing angle and pixel division for gradations, and it is necessary to perform different driving for each pixel division of gradations. As a result, the aperture ratio also decreases.
However, in this vertical alignment type liquid crystal, when the liquid crystal is viewed at an angle, the transmittance is high in the middle of the signal level, so even if a backlight unit with relatively high front brightness is used, The tangled image looks bright.
Regarding responsiveness, it is inferior to TN type, but better than IPS, and it is easy to obtain relatively high response.
If an attempt is made to use the signal level up to a high level in order to increase the transmittance, the gradation will be greatly disturbed depending on the viewing angle in a bright part, so that the transmittance cannot be increased much.

<Retardation film>
Attempts have been made to widen the viewing zone by using a film having negative uniaxial refractive index anisotropy for the vertically aligned liquid crystal.
However, this film is effective when the liquid crystal is oriented in the vertical direction, and is not corrected for halfway gradations, so that the gradation changes depending on the viewing angle. It is hard to say that it is effective.
In addition, it is very difficult to solve the problem that the color change is large in the middle gradation, particularly with respect to blue having a short wavelength (400 to 500 nm).

<Diffusion film>
Moreover, the technique which expands a visual field by arrange | positioning a diffusion film in the front surface of a liquid crystal display device is known (patent document 1).
However, although these techniques have a viewing zone expansion effect or an inversion prevention effect, they do not sufficiently suppress color change.

In addition, in order to suppress a decrease in contrast due to the light passing through in an oblique direction coming to the front, there is known one that strongly collects the light from the backlight in the front direction (Patent Document 2).
However, in such a technique, since it is necessary to collect light more strongly in the front direction, the structure of the backlight is complicated and expensive, and the efficiency tends to decrease.
In addition, these do not particularly specify the portion of the diffusion film, do not refer to the color correction effect, and cannot be considered to sufficiently suppress the color change.

<Tone brightness adjustment>
In order to compensate for this, the front gamma was increased to compensate for the decrease in brightness caused by the increase in front brightness. The bright colors are so painful to the eyes.
This is more noticeable as the screen becomes larger.
2004 Liquid Crystal Volume 8 Issue 2 Japanese Patent Laid-Open No. 10-10513 JP 20044763 A

The present invention relates to a liquid crystal display device, particularly a vertically-aligned liquid crystal television, capable of color correction that suppresses changes in gradation and color depending on viewing angle while suppressing a decrease in brightness, a decrease in contrast, and blurring. Furthermore, it aims at providing the polarizing element and liquid crystal display device using the same.
In particular, the main solution is to prevent the difference between the image viewed from the front and the image viewed from an angle with respect to the screen normal.

The liquid crystal image display device according to the present invention comprises:
Light scattering film having a particulate region (inner surface scatterer) having a size of 0.1 to 0.5 μm and having a different refractive index that scatters light in the visible light wavelength region more strongly (Mie scattering) depending on the particle size Is applied to a liquid crystal display element in combination with a polarizing film,
In a liquid crystal image display device that defines a display image by a vertical alignment type or twisted nematic (TN) alignment type liquid crystal display element provided with the light scattering film on the observer side of the polarizing plate on the observer side,
When observed within a range of ± 45 degrees with respect to the screen normal, the change in gamma is within 0.5, and the change in luminance when the input luminance signal value is 50% of the full range is within 40%. To do.

According to the present invention, in an environment such as a normal home living room, the liquid crystal image is such that the image does not fade, the color changes little, the image does not become dark, and the impression of the image does not change. A display device is possible.
In addition, when trying to obtain such an image by the above method, the light use efficiency generally decreases and the power consumption increases, but the use efficiency is increased by means such as the above solution. Therefore, a liquid crystal image display device useful for reducing the environmental load can be obtained at low cost.

  As the liquid crystal display device used here, the polarizing plate is crossed Nicol, and the liquid crystal is tilted in various directions, such as being made into multi-domain with normal black. A liquid crystal panel can be used.

In addition, the polarizing plate is crossed Nicol, a normal white, twisted nematic type liquid crystal. By applying an electric charge, the twist of the liquid crystal is eliminated, and the polarized light passing through the liquid crystal does not rotate and blocks the light. Such a TN liquid crystal panel can also be used.
In this case, as the diffuser, a material that strongly scatters is used, and a haze value of 60 or more is desirable.

As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable.
In addition, when providing a protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.
The polarizer and the protective film are usually in close contact with each other via an aqueous adhesive or the like.
Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, water-based polyurethane, water-based polyester, and the like.
You may give a scattering characteristic by disperse | distributing a spherical body in these adhesive agents.
In this way, since the adhesive layer and the diffusion layer can be used together, the cost can be reduced by omitting the steps.

  Further, the opposite surface of the protective film may be subjected to a hard coat layer, antireflection treatment, antisticking, antifouling, antistatic treatment, or treatment for diffusion or antiglare.

The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc., by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film.
The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art.
In addition, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.

The anti-glare treatment is performed for the purpose of preventing the external light from being reflected on the surface of the polarizing plate and obstructing the visual recognition of the light transmitted through the polarizing plate. For example, a rough surface by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a conversion method or a method of blending transparent fine particles.
The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used.
When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure.
The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

<Viewing environment>
When watching TV images, a common installation method is to install it at the corner of a room.
In many homes, the corner of a room is about 90 degrees, and it is common to install it at an angle of 45 degrees.
In such a case, it can be assumed that the observer is in a range of 45 degrees with respect to the normal of the screen. Therefore, since it is assumed that the image is observed within a range of ± 45 degrees with respect to the screen normal, it is desirable that a clear image is observed within this range. For public displays, master monitors, etc., it is preferable to assume a wider range, for example, a range of 60 degrees with respect to the normal of the screen. Of course, there are cases where observation is performed in other cases as well, but even in this case, it is desirable that there is no failure such as gradation inversion and that observation can be performed generally satisfactorily.

Usually, when enjoying video at home, a lot of people appear, and they are particularly sensitive to changes in facial impressions.
In particular, the impression of the skin color of women and children is important.
The inventors have observed images on various commercially available liquid crystal display devices or improved liquid crystal display devices, and when the gamma changes and becomes soft, the skin color looks worse and the skin color becomes darker. I found out that I received the impression of being tanned.
Also, from various experiments, by limiting the change in the gradation characteristics and brightness of the liquid crystal display device within a certain range, the change in the impression of the image will not be a problem for practical viewing at home. I found.
Conventionally, since a self-luminous video display device such as a CRT television has been used, such knowledge has not been obtained.
Further, in the conventional liquid crystal display device, the gradation characteristic and the brightness change of the intermediate color due to the change of the viewing angle have not been realized so that the impression of the image is not practically problematic in normal home viewing. It was.

<Change in gamma>
In the gradation characteristics, the gamma value greatly affects the impression of the video.
For example, NTSC, which is a broadcasting standard in Japan, is set to 2.2 as a standard for the amount of change, and PAL standard used in Europe and the United States is set to 2.6. The difference in video due to the difference in these standards is not so much that the user feels a sense of incongruity or a difference in impression, and from these facts, changes within about 0.5 are considered not to affect the impression of the video.
This gamma is considered to be appropriate when the input signal level, which is a signal that is often used other than highlighting, is up to 50% of the full range, except for the portion of 10 cd / m ² or less that is particularly dark and easily crushed. It is done.
When measuring, for example, in a normal liquid crystal, the gamma change is severe in the direction of 45 degrees obliquely in the screen, and it is desirable to perform along this.

<Color change>
With such a display, there was no impression that the image became white as if the entire image was hazy, and the reproducibility of the human skin color was also good.
Also, in a normal video display device, with such gradation characteristics, there is color adaptation of the eyes, and color changes are not particularly noticeable, but as color changes, changes in the U'V 'color system As the amount ΔU'V ', (U'xU' + V'xV ') ^1/2 index, and by making ΔU'V' 0.04 or less in the above observation angle range, the color change is substantially reduced. An unperceived display can be obtained.
For those demanding more stringent quality, ΔU′V ′ is preferably 0.02 or less.
As the test color at this time, for example, a color in the vicinity of 8 test colors defined in CIE 1974, a color in the vicinity of 15 test colors in JISZ8726, or a color in the vicinity of the Munsell color chart may be used.

<Brightness change>
As for the brightness of the screen, the input brightness value is frequently used up to 50%, and the bright skin color is also in the vicinity of this. Therefore, the change in the brightness value in the bright part up to 50% should be small. It is difficult to recognize changes in image brightness.
As a reference for the allowable value of this change amount, if the V value in the Munsell color chart is referenced, if it is a luminance difference of about 5 and 4, it is classified as gray as defined in JIS, and usually the same It can be recognized as a color.
However, when it changes to about 3, the color classification itself is defined as dark gray, and it is easy to recognize that the color is different.
Therefore, since the Yc value as the luminance difference is 19.27 and 11.70, it is considered appropriate to define 40% as the amount of change from the ratio. Even when viewing the video with the degree of change, the difference in the impression that the skin color tans could not be recognized.
Further, as a more severe application, the ratio between 19.27 and 15.19 may be suppressed to about 20% from the difference between about 5 and 4.5.

<With diffusion film>
In order to realize such a liquid crystal display device, a diffusion film is arranged on the front polarizing plate of the liquid crystal in a vertical alignment type liquid crystal in which the input signal is about 50% and the luminance does not change from any angle but the gamma value changes. By doing so, the light in each direction is sufficiently mixed, and the above-described liquid crystal display device can be realized.
At this time, by having a diffuser having a size of 0.1 to 0.5 μm that is a Mie scattering region as a diffuser, the wavelength dependency that corrects the wavelength dependency of the liquid crystal and the retardation film is effectively improved. Color correction is performed.

  In addition, when such a film is used for a vertically aligned liquid crystal, the change in gamma is usually too large to be used at a signal level that provides a high transmittance. By inserting, there is a possibility that such high transmittance can be used.

<Attachment function>
The surface of the protective film opposite to the diffusion layer may be subjected to a hard coat layer, antireflection treatment, anti-sticking, antifouling, antistatic, or treatment for diffusion or antiglare.
Further, it can be used together with a retardation film having negative uniaxial anisotropy.

<Required brightness>
In Japan's living environment, the average illuminance is about 100 lux, so the brightest white luminance can be the most efficient and gentle to the eyes by using a backlight unit so that the luminance is 30 cd / m ² .
When the highlight portion is taken into consideration, if the luminance is about 60 cd / m ^{2, the} expressive power can be further increased.
Further, since the illuminance is about 1000 lux when considering store sales, the brightest white luminance needs to be set to 300 cd / m ² .

  Furthermore, in the case of a conventional monitor, a good image display device was obtained by collecting light on the front side for observation from the front side of the monitor. In such a television, there is not always a display device in front of the viewer. Therefore, high brightness is required to obtain a good image with sufficient brightness at various angles.

On the other hand, in recent years, in order to reduce the load on the environment or improve the carrying of the battery when carrying it, there is an increasing demand for increasing the light use efficiency of the backlight unit.
Therefore, in order to achieve both of these, the light use efficiency of the backlight unit becomes important.

<Brightness varies with illuminance>
Since the human eye changes the brightness that it feels optimal according to the brightness of the surroundings, it is desirable to change the brightness of the screen according to the surrounding illuminance.
For example, since there is an illuminance of about 1000 Lux at a storefront, in this case, the front luminance of the ideal white plate is 1000 / 3.14≈about 300 cd / m 2, so this luminance should be white.
Usually, indoor artificial lighting does not watch images and environments brighter than this, so the specs are sufficient.
In Japan's living environment, the average illuminance is about 100 lux. By controlling the backlight unit so that the brightest white luminance is 30 cd / m ² , it is the most efficient and gentle to the eyes. .
In consideration of the highlight portion, if the luminance is about 60 cd / m ^{2, the} expressive power can be further increased.
In addition, when it is supposed to be used outdoors, it is better to devise special measures under strong sunlight.
For example, a low reflection coating or a liquid crystal display device incorporating a reflection component using external light may be employed.

Power consumption can be suppressed by using a mechanism that includes a sensor that measures illuminance and changes the brightness of the backlight unit according to the sensor value in accordance with the ambient brightness.
In addition, this makes it possible to reduce the black luminance at the same time in a dark environment, so that it is possible to obtain an image in which black is tightened.

<Highlight gamma reduction>
Further, in the LCD, it is necessary to adjust the brightness of the backlight unit to the brightest screen, so that the brightness of the backlight unit can be suppressed if the brightness of the brightest part can be suppressed.
By the way, the brightest part like this is a part of the highlight.
Even if the brightness of such a portion is somewhat reduced, the overall brightness of the image is not affected.

For example, for NTSC, the original gamma is 2.2. For an input signal of 75%, the luminance is 53% for 100% and 47% for PAL.
On the other hand, a signal above 75% can be considered as a highlight, so even if it is expressed with a beautiful gradation, the image is hardly affected.
In order to maintain the brightness of the entire image, it is only necessary to set the gamma so that the luminance is higher than the maximum of about 50%. Therefore, when the input signal is 50 to 75%, the gamma value is decreased. In a frequently used signal range of about 0 to 50%, the luminance can be increased from 1.5 times to about 2 times.
For example, if 75% of the maximum luminance is set when the input is 75% of the full range, an image in which the luminance is about 50% brighter can be obtained.
As a numerical value, this level is good empirically, but it is not particularly limited to this luminance value, and a value lower than gamma of a lower signal level may be used above about 75%.

  Such a situation can only be achieved by suppressing the change in gamma because the setting is very difficult in a liquid crystal display device in which gamma changes depending on the viewing angle.

<High transmission color filter>
In addition, since the color filter for performing full color display on the liquid crystal display device has low transmittance, the luminance of display can be increased by increasing the transmittance.
In a normal monitor or the like, characters and the like are displayed using the primary color, so even if a bright filter with low saturation is used, the image quality does not improve.
However, in a display that mainly inputs video, especially in a bright part, it becomes like a highlight with reduced saturation, so a bright filter with low saturation is used to express that part. Thus, a color filter with higher transmittance can be obtained.
As a result, the luminance can be increased by about 50 to 100%.
As such a filter, if white whose transmittance does not change depending on the wavelength is used, a filter having a high transmittance can be obtained easily.
If an emerald green filter is used, the transmittance can be increased and the color gamut can be expanded.

Similarly, it is also possible to improve the luminance by using a reflective polarizing plate or an optical sheet that condenses light on the front surface.
With these devices, it is possible to increase the light use efficiency of the lamp of the backlight unit to about three times as compared with the case where there is nothing.
A normal liquid crystal television has a rating of about 100 W for a 20-inch television, and can be reduced to about 50 W to 75 W at a minimum.
In addition, in the store display, the illuminance is very high, and may be about 1000 Lux.

On the other hand, the illuminance of a normal living room is about 100 lux, and even in a bright living room is about 300 lux. Even with a TV set to about / m 2, sufficient video can be obtained, so that the rated output can be further reduced to about 17 to 25 W without degrading the video quality, and the power supply circuit The cost of the backlight unit can be reduced.
Furthermore, by using a mechanism that changes the brightness of the backlight unit in accordance with the ambient brightness, it is possible to reduce power consumption to about several watts in a normal living environment.

In addition, the liquid crystal image device as described above is perceived as a screen that is not covered by the above-mentioned range, the impression that the skin is dark, the skin color is poor, or the color impression due to the decrease in brightness is recognized differently. Depending on the eye characteristics, it is indispensable and not just a design value to achieve the object of the present invention.
It should be noted that further suppressing the change from the above numerical values is uneconomical because the effect is hardly recognized.
Further, in the conventional invention, there is one in which a diffusion film is arranged on the front surface of the liquid crystal panel for the purpose of expanding the viewing area for a monitor or the like that mainly displays characters, etc. It is not the main purpose, it is an invention whose main purpose is to provide a liquid crystal image display device that has little change in gradation and brightness from any point of view and does not change the appearance. For example, if there is no blurring of characters and the conventional way of capturing the viewing angle, the idea itself is different because it focuses on expanding the range where characters can be read and colors close to the primary color can be recognized. It cannot be easily conceived from technology.

M-110, which is an acrylic monomer, is mixed with SN-12T of vinyl acetate dissolved in MEK at a ratio of 5: 1 by weight, and applied to Fuji Photo Film's TAC (80 μm thick) Fujitac. Then, the solvent was volatilized by heating, the film was applied to a film thickness of about 18 μm, and after irradiation with about 500 mJ / cm ^{2 of} ultraviolet rays, the film was heated at 120 ° C. for 10 minutes to obtain a phase-separated light diffuser. This film was bonded to the surface of KLV-15AP of a 15-screen type liquid crystal television.
When the change in the vertical direction of color was measured using Ezlite manufactured by ELDIM, the change in gamma was 1.3 on the front and 1.8 and 45 degrees.
The color change was suppressed to 0.04 by ΔU'V '.
Further, the decrease in luminance with a full-range input signal due to the mounting was about 20%.
In addition, at this time, the change in luminance when the input signal was about 50% of the full range could be suppressed to about 20%.

The graph showing the gradation characteristic when it measures at 0 degree | times, 30 degree | times, and 45 degree | times with respect to the screen normal in the diagonal direction of the video display apparatus of this invention. The graph showing the gradation characteristic when it measures at 0 degree | times, 30 degree | times, and 45 degree | times with respect to the screen normal in the diagonal direction of the VA system video display apparatus. The graph showing the gradation characteristic when it measures at 0 degree | times, 30 degree | times, and 45 degree | times with respect to the screen normal in the diagonal direction of the video display apparatus of an IPS system.

Claims (4)

Light scattering film having a particulate region (inner surface scatterer) having a size of 0.1 to 0.5 μm and having a different refractive index that scatters light in the visible light wavelength region more strongly (Mie scattering) depending on the particle size Is applied to a liquid crystal display element in combination with a polarizing film,
In a liquid crystal image display device that defines a display image by a vertical alignment type or twisted nematic (TN) alignment type liquid crystal display element provided with the light scattering film on the observer side of the polarizing plate on the observer side,
When observed within a range of ± 45 degrees with respect to the screen normal, the change in gamma is within 0.5, and the change in luminance when the input luminance signal value is 50% of the full range is within 40%. LCD image display device.   It has a measuring instrument that can measure the illuminance of the viewing environment, and has the function of adjusting the display brightness by adjusting the brightness of the backlight unit and the transmittance of the liquid crystal panel according to the measured illuminance of the viewing environment The liquid crystal image display device according to claim 1.   3. The liquid crystal image display device according to claim 1, wherein when the input luminance signal value is 75% of the full range, the luminance value is 75% or more of the full range.   4. The liquid crystal image according to claim 1, wherein the pixels of the liquid crystal cell are composed of four or more cells of red, green, blue, and white having higher transmission luminance than the red or green pixel. Display device.

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