JP4599903B2 - Liquid crystal display, color filter for liquid crystal display, array substrate for liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display of a multi-orientation division type vertical alignment mode, a color filter used for manufacturing a liquid crystal display, and an array substrate.

In recent years, liquid crystal displays (LCDs) have attracted attention as flat displays, and due to their thinness, light weight, low power consumption, and flickerless characteristics, the market is growing rapidly, mainly for notebook personal computers (PCs) and PC monitors. Expanded. Recently, large LCDs have also been used for TVs for which CRT has been the mainstream.
When considering a large LCD as described above, uniform brightness and contrast regardless of the viewing angle are required over the entire screen. However, in the TN alignment mode widely used conventionally, the narrow viewing angle has been a big problem.

Therefore, in recent years, many viewing angle improvement modes such as an In Plane Switching mode (IPS mode) and an optical compensation TN mode have been developed. One of such viewing angle improvement modes, the multi-orientation division type vertical alignment mode (MVA mode) is currently widely used because of its advantages of (1) wide viewing angle, (2) high contrast, and (3) high-speed response. It attracts attention. In particular, the contrast characteristic can be up to about 500: 1, which is remarkably higher quality than other modes.
This MVA mode is a method in which protrusions are provided in the liquid crystal panel to control the tilt direction of the liquid crystal molecules without using the rubbing technique in order to divide the plurality of alignments (the liquid crystal molecules are aligned in a plurality of directions). Yes (see, for example, Patent Document 1).

  The protrusions that control the alignment of the liquid crystal molecules can be, for example, 45 ° zigzag stripes, and are designed so that the alignment direction in one pixel is divided into four and the divided areas are equal. Yes. The protrusions can be provided on both the color filter side and the array substrate side. In this case, when the two substrates are opposed to form a cell, both protrusions are arranged alternately. Such protrusions have a role of imparting a pretilt angle to the liquid crystal molecules and distorting the lines of electric force. Due to these two effects, the liquid crystal molecules are aligned in a plurality of different directions when a voltage is applied. . At this time, when the voltage is turned off, the liquid crystal stands black with respect to the substrate, and when the voltage is turned on, all the liquid crystal molecules including those on the protrusions are horizontally tilted to display white.

Here, the problem of the liquid crystal display is the efficiency of light used for display. The LCD performs display by light transmitted through a liquid crystal display such as a backlight and external light. As a measure for improving the light efficiency, a measure for reducing the area of the light shielding portion and increasing the aperture ratio of the pixel is taken.
The protrusion is formed on the pixel opening, and its exclusive area is about 20% of the opening. If the projection transmittance is low at this time, the brightness of the liquid crystal display and the display quality are deteriorated.
Japanese Patent No. 2947350

The present invention has been made in view of the above problems, and an object thereof is to provide a liquid crystal display with high display quality easily and inexpensively in a liquid crystal display using the MVA mode.

  In the liquid crystal display of a multi-orientation division type vertical alignment mode, at least one substrate includes protrusions for controlling the alignment directions of liquid crystal molecules of a liquid crystal layer formed between a pair of opposing substrates. The liquid crystal display is characterized in that the transmittance of the protrusion in the visible light region is 80% or more.

  Further, the present invention is the liquid crystal display according to the above invention, wherein the protrusion is a protrusion formed by a photolithography method using a photosensitive resin.

  The present invention is the liquid crystal display according to the invention, wherein the protrusion is a protrusion irradiated with ultraviolet rays before post-baking in a photolithography method.

  Further, the present invention is a color filter for a liquid crystal display of a multi-orientation division type vertical alignment mode, comprising a protrusion for controlling the alignment direction of liquid crystal molecules in the liquid crystal layer to a plurality, and the transmittance of the protrusion in the visible light region is 80 % Is a color filter for a liquid crystal display.

  The present invention is the color filter for a liquid crystal display according to the above invention, wherein the protrusion is a protrusion formed by a photolithography method using a photosensitive resin.

  The present invention also provides the color filter for a liquid crystal display according to the above invention, wherein the protrusion is a protrusion irradiated with ultraviolet rays before post-baking in a photolithography method.

  The present invention also provides a multi-orientation-divided vertical alignment mode liquid crystal display array substrate having protrusions for controlling the alignment direction of liquid crystal molecules in the liquid crystal layer to a plurality, and having a transmittance in the visible light region of 80. % Or more of the liquid crystal display array substrate.

  According to the present invention, in the array substrate for a liquid crystal display according to the above invention, the projection is a projection formed by a photolithography method using a photosensitive resin.

  Further, the present invention is the array substrate for a liquid crystal display according to the above invention, wherein the protrusion is a protrusion irradiated with ultraviolet rays before post-baking in a photolithography method.

  According to the present invention, the transmittance of the alignment control protrusions is remarkably improved, and the liquid crystal display using the MVA mode can be easily and inexpensively made into a liquid crystal display with high display quality.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partial sectional view showing an embodiment of a liquid crystal display according to the present invention. In addition, FIG.
These are top views of the color filter 11 which comprises the liquid crystal display 1 shown in FIG. A cross section taken along line XX ′ in FIG. 2 corresponds to a cross section of the color filter 11 in FIG.

As shown in FIGS. 1 and 2, the liquid crystal display 1 has a color filter 11 and an array substrate 21 facing each other at a predetermined interval, a peripheral portion is sealed with a seal member (not shown), and a liquid crystal is disposed in the gap portion. This is a transmissive liquid crystal display in which the layer 2 is formed.
Although not shown, polarizing plates are disposed outside the color filter 11 and the array substrate 21, respectively.

  In the color filter 11 of the present invention constituting the liquid crystal display 1 of the present invention, a common transparent electrode 15 is formed so as to cover the black matrix 13 and the colored layer 14 formed on the transparent substrate 12, and the common transparent electrode 15 is further formed. A plurality of protrusions 16 are formed on the liquid crystal layer 2 to control the alignment direction of the liquid crystal molecules in a plurality of directions, and an alignment film 17 is formed so as to cover these protrusions 16.

As the photosensitive resin for forming the protrusions 16, a known negative resist or positive resist can be used. For example, a photosensitive resin made of an acrylic resin, a novolac resin, or the like can be used.
The protrusion 16 is formed in a stripe shape or a dot shape on the colored layer 14 at the opening of the black matrix 13, and the cross-sectional shape of the protrusion 16 can be a semicircle, a triangle, or the like, and the height of the protrusion 16 is 0. The width can be set to about 8.0 to 2.0 μm and the width can be set to about 4.0 to 25.0 μm.

  The area occupied by the protrusion 16 with respect to the opening is set to about 5 to 25%, and the light transmittance in the visible light region is 80% or more, more preferably 90% or more. If it is lower than this, the color purity of the colored layer will be lowered and the light transmittance will be lowered, leading to a reduction in display quality.

FIG. 3 is a partial cross-sectional view showing another embodiment of the liquid crystal display of the present invention. In FIG. 3, the liquid crystal display 31 is a transmission type in which the color filter 41 and the array substrate 51 are opposed to each other at a predetermined interval, the peripheral portion is sealed with a seal member (not shown), and the liquid crystal layer 32 is formed in the gap portion. It is a liquid crystal display.
The array substrate 51 of the present invention includes a TFT 53 for driving liquid crystal and a transparent pixel electrode 54 on a transparent substrate 52, and a projection 55 is formed on the transparent electrode 54 so as to cover the transparent pixel electrode 54 and the projection 55. An alignment film 56 is formed.

The projections 55 constituting the array substrate 51 can control the alignment direction of the liquid crystal molecules of the liquid crystal layer 32 in a plurality of directions in cooperation with the projections 46 of the color filter 41.
Similar to the protrusion 16 described above, the protrusion 55 has a light characteristic such that the light transmittance in the visible light region is 80% or more, more preferably 90% or more. If it is lower than this, the color purity of the colored layer will be lowered and the light transmittance will be lowered, leading to a reduction in display quality.

  Further, the protrusion in the present invention is a protrusion formed by a photolithography method using a photosensitive resin. Further, the protrusion is characterized in that it is decolored by being irradiated with ultraviolet rays before post-baking (thermosetting treatment) in the photolithography method. As the photosensitive resin used for forming the protrusions, either a negative resist or a positive resist can be used. In the case of a negative resist, at the time of exposure through a photomask, the portion that becomes a projection is cured by ultraviolet rays irradiated from the opening of the photomask, and a projection is formed after development. That is, before the post-baking (thermosetting process) to be performed after development, the protrusions are irradiated with ultraviolet rays and decolorized.

On the other hand, in the case of a positive resist, during exposure through a photomask, the portion is photodegraded by ultraviolet rays irradiated from the opening portion of the photomask, and the unexposed portion remains after development to form protrusions. Is done.
In this unexposed portion, the photosensitive agent remains. Prior to post-baking (thermosetting) after development, the unexposed areas where the photosensitizer remains are irradiated with ultraviolet rays to decompose the photosensitizer, so that the protrusions during post-baking (thermosetting) The coloring can be suppressed and the transmittance can be improved.

Hereinafter, the present invention will be described in detail by Example 1.
(UV irradiation effect with VA resist alone)
As a glass substrate for a color filter, a glass substrate (Corning 1737 glass) having a size of 300 × 400 mm and a thickness of 0.7 mm was prepared. After this substrate was washed according to a conventional method, a novolac resin VA (Vertical Alignment) resist as a positive photosensitive resin was applied to a thickness of 1.3 μm by spin coating.
Sample 1 was prepared by performing a thermosetting treatment at 230 ° C. for 1 hr without irradiating ultraviolet rays before the thermosetting treatment.
Sample 2 was produced by irradiating ultraviolet light corresponding to 1/2 of the resolvable exposure amount of the VA resist, and then performing a thermosetting treatment at 230 ° C. for 1 hour.
Sample 3 was produced by irradiating the same amount (1/1) of ultraviolet light as the resolvable exposure amount of the VA resist, followed by thermosetting treatment at 230 ° C. for 1 hr.
Sample 4 was prepared by irradiating UV light twice as much as the resolvable exposure amount of the VA resist (2/1), followed by thermosetting treatment at 230 ° C. for 1 hr.

After the heat curing treatment, the appearance of Sample 1 was changed to brown, Sample 2 was pale yellow, and Samples 3 and 4 were transparent.
As shown in FIG. 4, when the spectral transmittance of each sample is compared, the change in the spectral transmittance of 400 to 600 nm in the visible light region is remarkable, and the transmittance in the vicinity of 435 nm of the blue peak region of the color filter is The transmittance of Sample 1 was 30%, Sample 2 was 80%, and Samples 3 and 4 had a transmittance of about 90%. In the comparison of the wavelength ranges of the green and red peaks of the color filter, the samples 1, 2, 3, and 4 showed about 80%. Spectral transmittance was measured using a microspectroscope. (Ultraviolet irradiation effect when a VA resist is formed on the colored layer)
As a glass substrate for a color filter, a glass substrate of 300 × 400 mm and a thickness of 0.7 mm (Corning 1737 glass) was prepared. This substrate was washed according to a conventional method to form a black matrix and R, G, B colored layers. After that, a novolak resin VA resist was applied as a positive photosensitive resin so as to have a thickness of 1.3 μm by spin coating.
Sample 5 was prepared by performing a thermosetting treatment at 230 ° C. for 1 hour without irradiating ultraviolet rays before the thermosetting treatment.
Sample 6 was prepared by irradiating with UV light twice as much as the resolvable exposure amount of the VA resist (2/1), followed by thermosetting treatment at 230 ° C. for 1 hr.
After the thermosetting treatment, the spectral transmittance was measured using a microspectroscope.

As shown in FIG. 5, the transmittance in the vicinity of 435 nm of the blue peak region of the color filter was 20% or less for sample 5 and 85% for sample 6. In comparison of the wavelength ranges of the green and red peaks of the color filter, both samples 5 and 6 showed 80% or more.
That is, it was recognized that the effect of the present invention was remarkable in the blue wavelength region.
At the time of color display, the display color is designed based on the transmittance balance of Blue, Green, and Red. However, in the sample 5, the display color is shifted to the yellow side because the transmittance of only Blue is reduced. Become. In the present invention, this transmittance is remarkably improved.
When a liquid crystal display was produced using this sample 6, the brightness of white display was improved by about 5% compared with the conventional method.

It is a fragmentary sectional view which shows one Example of the liquid crystal display by this invention. It is a top view of the color filter which comprises the liquid crystal display shown in FIG. It is a fragmentary sectional view which shows the other form of the liquid crystal display of this invention. It is explanatory drawing which compares the spectral transmittance of each sample in a VA resist single-piece | unit. It is explanatory drawing at the time of forming VA resist on a colored layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 31 ... Liquid crystal display 2, 32 ... Liquid crystal layer 11, 41 ... Color filter 12, 22, 52 ... Transparent substrate 13 ... Black matrix 14 ... Colored layer 15 ... Common transparent electrodes 16, 55, 46 ... projections 17, 56 ... alignment films 21, 51 ... array substrate 53 ... TFT
25, 54 ... Transparent pixel electrode

Claims (9)

In a liquid crystal display of a multi-orientation division type vertical alignment mode, at least one substrate has a semicircular or triangular cross section for controlling the alignment direction of liquid crystal molecules in a liquid crystal layer formed between a pair of opposing substrates to a plurality. In preparation for
This substrate has a black matrix on one side,
The area occupied by this protrusion with respect to the opening of this black matrix is 5 to 25%,
The transmittance of the protrusion in the blue region is about 90%,
The transmittance in the green region and red region of this protrusion is about 80%,
LCD height of the protrusions, wherein the Ru 0.8~2.0μm der.   The liquid crystal display according to claim 1, wherein the protrusion is a protrusion formed by a photolithography method using a photosensitive resin.   The liquid crystal display according to claim 2, wherein the protrusion is a protrusion irradiated with ultraviolet rays before post-baking in a photolithography method. In a color filter for a liquid crystal display of a multi-orientation division type vertical alignment mode, a protrusion having a semicircular or triangular cross section for controlling the alignment direction of the liquid crystal molecules of the liquid crystal layer to a plurality,
The area occupied by this protrusion with respect to the opening of this black matrix is 5 to 25%,
The transmittance of the protrusion in the blue region is about 90%,
The transmittance in the green region and red region of this protrusion is about 80%,
Color filters for liquid crystal display height of the protrusions, wherein the Ru 0.8~2.0μm der.   5. The color filter for a liquid crystal display according to claim 4, wherein the protrusion is a protrusion formed by a photolithography method using a photosensitive resin.   6. The color filter for a liquid crystal display according to claim 5, wherein the protrusion is a protrusion irradiated with ultraviolet rays before post-baking in a photolithography method. In an array substrate for a liquid crystal display of a multi-orientation division type vertical alignment mode, a projection having a semicircular or triangular cross section for controlling the alignment direction of the liquid crystal molecules in the liquid crystal layer to a plurality is provided.
The area occupied by this protrusion with respect to the opening of this black matrix is 5 to 25%,
The transmittance of the protrusion in the blue region is about 90%,
The transmittance in the green region and red region of this protrusion is about 80%,
An array substrate for a liquid crystal display height of the protrusions, wherein the Ru 0.8~2.0μm der.   8. The array substrate for a liquid crystal display according to claim 7, wherein the protrusion is a protrusion formed by a photolithography method using a photosensitive resin.   9. The array substrate for a liquid crystal display according to claim 8, wherein the projection is a projection irradiated with ultraviolet rays before post-baking in a photolithography method.

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