JP2002040407A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal element with uniform liquid crystal layer thickness by devising the arrangement of fixing spacers in a liquid crystal element having a color filter. SOLUTION: Planar positions of the arrangement of the fixing spacers are determined to be on gap parts between the color filters so as to uniformize the liquid crystal layer thickness or are determined to be on regions on the color filter sufficiently far inside from an outer peripheral part of the color filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device having a fixed spacer in which a spacer for regulating the thickness of a liquid crystal layer is fixed on a substrate.

[0002]

2. Description of the Related Art A liquid crystal display device comprises two substrates on which transparent electrodes are formed, and a liquid crystal is sealed between the two substrates with a sealing material. In the case of a color liquid crystal display element, a color filter having a plurality of spectral transmittance characteristics is formed on one substrate. In order to make the liquid crystal layer thickness of the liquid crystal sealed between the two substrates uniform, a spacer for regulating the liquid crystal layer thickness is disposed between the two substrates. This spacer is bonded and fixed to one of the substrates so as not to move between the two substrates.

Hereinafter, a conventional liquid crystal display device will be described in detail with reference to the drawings. 3A and 3B are schematic partial views of a conventional liquid crystal display element, in which FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along the line AA in FIG. A plurality of color filters 2 having different spectral transmittance characteristics are provided on one substrate 1 having an insulating property such as glass. The color filter and the other substrate are provided with a transparent electrode 3 formed of a transparent electrode material made of indium-tin-oxide (ITO) or the like into a desired shape by a photolithography method. Although not shown, an alignment film for aligning liquid crystal molecules in a desired direction is provided on the transparent electrode 3. A fixed spacer 4 is provided on one substrate 1. The fixed spacers 4 are used to make the distance between the transparent electrodes on the two substrates uniform and to make the layer thickness of the liquid crystal 5 filled in the gap between the transparent electrodes uniform. The fixing spacer 4 is formed by applying a fixing spacer material made of a photosensitive polymer resin onto the substrate 1 and then exposing and hardening a region serving as the fixing spacer with an ultraviolet ray through a photomask, and developing an uncured portion other than the region serving as the fixing spacer. It is formed by removing. The two substrates 1 are bonded together by a sealing material (not shown) such as an epoxy resin disposed on the outer periphery of the display screen, and a liquid crystal 5 is filled and sealed in a display screen area surrounded by the sealing material.

At this time, the thickness of the liquid crystal layer is an important factor that affects the display characteristics of the liquid crystal display device. In a liquid crystal display device, linearly polarized light incident on the liquid crystal display device becomes elliptically polarized light in the liquid crystal layer. At this time, since the degree of elliptically polarized light depends on the wavelength, the birefringence of the liquid crystal material, and the thickness of the liquid crystal layer, the light emitted from the liquid crystal display element is colored light. For this purpose, a retardation film for compensating for this or a compensating liquid crystal cell having a reverse twist with respect to the liquid crystal display element is arranged on the emission side of the liquid crystal display element to make the colorless light. The birefringence characteristic of this liquid crystal material is an important factor related to display quality especially in a super twisted nematic (STN) type liquid crystal display element in which the orientation direction of liquid crystal molecules is twisted by 90 degrees or more between substrates. Is an important constituent material that determines the display quality of the liquid crystal display element. In the method in which the fixed spacers are formed by exposing and curing the photosensitive resin as described above, the positions of the fixed spacers arranged on the substrate can be made uniform by layout means such as a photomask. At the same time, since the two substrates are fixedly arranged between the one substrates, the two substrates can be evenly supported by the fulcrum, which is a fixed spacer located at an evenly spaced position, without moving in the liquid crystal display element.

[0005]

However, in a liquid crystal display device having a color filter and a fixed spacer, it is difficult to make the thickness of the liquid crystal layer uniform by the fixed spacer due to the influence of the end shape of the color filter. There is a problem that is reduced. Hereinafter, the problem that the thickness of the liquid crystal layer becomes uneven and the display quality deteriorates will be described in detail with reference to the drawings. FIG. 4 is a schematic cross-sectional view of a liquid crystal display device having a color filter and a fixed spacer, and schematically shows an end of the color filter. In this description, the fixed spacer 4 is formed on the substrate side facing the substrate on which the color filter 2 is formed, but may be formed on the substrate side on which the color filter 2 is formed. In the conventional liquid crystal display element, the fixed spacer 4 is formed in a pixel which is a minimum unit constituting the display screen, that is, in a region other than a region where the transparent electrodes 3 on the two substrates overlap when viewed from a plane. . This is due to the intention of increasing the pixel area contributing to the display screen as much as possible to make the display screen brighter.

[0006] The color filter has a plurality of systems in which a photosensitive polymer resin in which pigments having different spectral characteristics are dispersed is coated on a substrate by a spinner coating method or a laminating coating method and then exposed and cured to develop and remove an unnecessary portion of the polymer resin. It is formed repeatedly. For example, when forming a color filter having two types of spectral transmittance characteristics of red, green, and blue in this order, after forming the red color filter 2R,
A photosensitive polymer resin material having a green spectral transmittance characteristic is applied on the substrate 1 including the red color filter 2R. After exposing and curing the photosensitive polymer resin material having a green spectral transmittance characteristic in a green color filter forming region, the photosensitive polymer resin material having a green spectral transmittance characteristic in an unexposed portion is developed and removed to obtain a green color filter. The filter 2G is formed.
The green color filter 2G thus obtained has a shape in which the red color filter 2R side end has a protrusion. next,
Similarly, for the blue color filter 2B, a photosensitive polymer resin material having a blue spectral transmittance characteristic is applied on the substrate 1 including the red color filter 2R and the green color filter 2G. After exposing and curing a photosensitive polymer resin material having a blue spectral transmittance characteristic in a blue color filter forming region, a photosensitive polymer resin material having a blue spectral transmittance characteristic in an unexposed portion is developed and removed. The filter 2B is formed. The blue color filter 2B thus obtained is the red color filter 2R side and the green color filter 2R.
Both ends on the G side have a shape having projections.

At this time, the heights of the projections of the green color filter 2G and the blue color filter 2B change depending on the relative positional relationship with the color filters of each color. This is because the color filter (2R, 2R,
This is because when the photosensitive polymer material to be formed next is applied on 2R and 2G), the adjacent color filter adjacent side is thicker and becomes thinner as the distance increases. That is, in practice, the height of the protrusion increases when the position of the adjacent color filter is close, and decreases when the position is distant. In the step of exposing the photosensitive polymer resin, the alignment is performed using the alignment pattern of the photomask and the alignment pattern formed on the substrate in order to expose a desired position, but depending on the accuracy of the exposure apparatus, Generally, a displacement of about several μm occurs. This shift occurs between the substrates and in the substrate due to thermal expansion of the substrate and the photomask due to mechanical and optical errors and thermal effects. Therefore, the color filter 2 has a shape in which the heights of the protrusions at the end portions are not uniform between the substrates and within the substrates.

That is, in the conventional liquid crystal display device, since the fixed spacer 4 is formed in the end region of the color filter 2 in which the height of the projection is not uniform, the fixed spacer 4 is formed by the influence of the end shape of the color filter. It is difficult to make the thickness of the liquid crystal layer uniform, and there is a problem that display quality deteriorates.

It is an object of the present invention to provide a liquid crystal display device in which the thickness of a liquid crystal layer is made uniform by a fixed spacer which is not affected by the end shape of a color filter, thereby improving the display quality. .

[0010]

To achieve the above object, the liquid crystal display device of the present invention employs the following constitution.
That is, the first configuration of the present invention provides a liquid crystal device including a color filter having spectral characteristics corresponding to pixels and a fixed spacer for regulating the thickness of a liquid crystal layer on a substrate. The position is a portion of the gap between the color filters. Further, a second configuration of the present invention is a liquid crystal device including a color filter having a spectral characteristic corresponding to a pixel and a fixed spacer that regulates a liquid crystal layer thickness on a substrate.
The planar arrangement position of the fixed spacer is a region on the color filter that is sufficiently inside from the outer peripheral portion of the color filter.

[Operation] The fixed spacer of the liquid crystal display element of the present invention is disposed in a region other than the region where the color filter is disposed. That is, the fixed spacer for regulating the thickness of the liquid crystal layer is directly disposed between the two substrates or between the transparent electrodes without passing through the color filter. Since the rigidity and uniformity are formed between the two substrates or the transparent electrodes, the thickness of the liquid crystal layer in the area that becomes the display screen is affected by the shape of the edge of the color filter by disposing a fixed spacer in this area. Thus, a liquid crystal display element having a uniform thickness over the entire display screen and improved display quality can be obtained. Further, the fixed spacer of the liquid crystal display element of the present invention is provided in a substantially central region on a pixel constituting a display screen, that is, each color filter 2R, 2G, 2B.
Are arranged in a substantially central region. In contrast to the non-uniform shape of the end portion of the color filter, a substantially central portion on the pixel has a color filter thickness over the entire display screen in order to develop a plurality of desired spectral transmittance characteristics in the process of forming the color filter. Are formed uniformly. In particular, it is essential for the STN-type liquid crystal display element to make the thickness of a plurality of color filters uniform. Therefore, by arranging the fixed spacer in a substantially central area on the pixels constituting the display screen, the thickness of the liquid crystal layer in the area to be the display screen becomes uniform over the entire display screen without being affected by the end shape of the color filter. Thus, a liquid crystal display device with improved display quality can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a liquid crystal display device in the best mode for carrying out the present invention will be described below with reference to the drawings. 1 and 2 are schematic partial views of a liquid crystal display device according to the present invention, wherein (a) is a plan view and (b) is AA of (a).
It is sectional drawing in a part.

In FIG. 1, a fixed spacer 4 is arranged in an area other than an area where a color filter 2 is arranged on an insulating substrate 1. After applying a fixed spacer material made of a photosensitive polymer resin on the substrate 1, the fixed spacer 4 is exposed and cured with ultraviolet rays through a photomask in a region other than a region where the color filter 2 is arranged, via a photomask.
The uncured portion other than the region serving as the fixed spacer is formed by developing and removing.

In FIG. 2, a fixed spacer 4 is arranged in a substantially central region of a pixel corresponding to a color filter 2 formed on an insulating substrate 1. The fixing spacer 4 is formed by applying a fixing spacer material made of a photosensitive polymer resin on the substrate 1 and then hardening the area to be the fixing spacer in a substantially central area of a pixel corresponding to the color filter 2 with ultraviolet rays via a photomask. The uncured portion other than the region serving as the fixing spacer is developed and removed.

In the description of FIGS. 1 and 2, the fixed spacer is formed on the substrate facing the substrate on which the color filter is formed, but may be formed on the substrate on which the color filter is formed. Further, the location and number of the fixed spacers are not limited to the examples of FIGS.

Coloring the fixing spacer material to black in order to prevent light leakage from the fixing spacer and light leakage due to alignment disorder around the fixing spacer is an effective means for improving display quality. Further, it is an effective means to prevent the light leakage by disposing a light shielding material such as chromium metal in a region where the fixing spacer is disposed.

[0017]

According to the liquid crystal display device of the present invention, in order to make the liquid crystal layer thickness of the display screen uniform, the arrangement of the fixed spacers requires a color filter which is not affected by the end of the color filter which causes the nonuniformity of the liquid crystal layer thickness. It is arranged in an area other than the area to be arranged.
In addition, the fixed spacers are arranged in a substantially central region of the display pixel which is not affected by the end of the color filter which causes the thickness of the liquid crystal layer to be nonuniform. As a result, the thickness of the liquid crystal layer can be made uniform over the entire display screen, so that a liquid crystal display element with good display quality can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a liquid crystal display device of the present invention, and is a partial view of a liquid crystal display device in which fixed spacers are arranged in a region other than a region where a color filter is formed.

FIG. 2 is a diagram for explaining the liquid crystal display device of the present invention, and is a partial view of the liquid crystal display device in which a fixed spacer is arranged in a substantially central region of a pixel.

FIG. 3 is a diagram for explaining a conventional liquid crystal display device, and is a partial view of the conventional liquid crystal display device.

FIG. 4 is a diagram for explaining a shape of a color filter end portion of the liquid crystal display element, and is a cross-sectional view of a color filter substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Color filter 3 Transparent electrode 4 Fixed spacer 5 Liquid crystal

Claims (2)

[Claims] 1. A liquid crystal device comprising a color filter having a spectral characteristic corresponding to a pixel and comprising a fixed spacer for regulating the thickness of a liquid crystal layer on a substrate. A liquid crystal display element characterized by the following: 2. A liquid crystal device comprising a color filter having a spectral characteristic corresponding to a pixel and a fixed spacer for regulating the thickness of a liquid crystal layer on a substrate, wherein the fixed spacer has a planar arrangement position on the color filter. A liquid crystal display element characterized by being a region sufficiently inside from the outer peripheral portion of the color filter.