JP3040943B2 - Color filter substrate and liquid crystal device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a color filter substrate used for a display element which performs multicolor display by a combination of lighting of respective colors, and a liquid crystal element using the same. More specifically, the present invention relates to a liquid crystal element that performs multicolor display by combining lighting of four colors of red, blue, green, and white.

[0002]

2. Description of the Related Art Conventionally, various types of liquid crystal elements for performing color display have been proposed, but generally, three (3) colors of red (R), blue (B) and green (G) are displayed. There is a type in which one pixel is formed by three dots, and a color display of up to eight colors is performed by a combination of ON and OFF.

However, in recent years, demands for color display quality have been increasing, and liquid crystal elements capable of displaying more colors are expected.

FIG. 1 shows an example of this,
This liquid crystal element 1 (hereinafter, referred to as “liquid crystal display element 1”) includes four color regions 2R, 2B, 2G, and 2W. These color regions 2R, 2B, 2G, and 2W are configured by filters of each color of red, blue, green, and white arranged on a substrate (base material) of the element, and configured to display each color. ing. The liquid crystal display element 1 displays the intermediate colors in addition to the above-described eight colors by a combination of lighting these color regions 2R,.

[0005] Each of these color filters is formed by patterning by photolithography on a substrate (base material) constituting an element. Since only one color filter can be formed by one photolithography, four times of photolithography have been performed at the time of manufacturing. Further, a photosensitive resin in which a coloring material is dispersed is used for forming the red, blue and green filters, and a photosensitive resin in which the coloring material is not dispersed is used for forming a white filter.

[0006]

However, since the white filter is formed of a photosensitive resin in which the coloring material is not dispersed as described above, the in-plane filter is formed in comparison with filters of other colors in which the coloring material is dispersed. The thickness distribution characteristics were significantly different. As a result, the thickness of each dot of the white filter obtained after patterning becomes non-uniform, and the thickness of the white filter and the thickness of filters of other colors become non-uniform,
The film thickness difference was about 1500 to 2000 °, and a large step was formed in one pixel on the liquid crystal side surface of the substrate having the color filter, so that flattening could not be achieved. Therefore, the orientation of the liquid crystal becomes non-uniform within one pixel of the liquid crystal display element, and the driving margin is reduced. In a liquid crystal display device having a small distance (gap) between opposing substrates, such as a display device using a ferroelectric liquid crystal, the problem is remarkable.

On the other hand, in the above-mentioned conventional example, it is necessary to perform patterning four times for each color, so that the manufacturing process becomes more complicated than that in which three color filters are formed, and the material cost and the manufacturing cost increase. There was a problem that would.

The present invention has been made in view of the above circumstances, and provides a color filter substrate capable of improving color display quality and reducing the level difference between filters for each color, and a liquid crystal element using the same. It is intended to provide.

It is another object of the present invention to provide a color filter substrate and a liquid crystal element which can reduce the number of times of patterning to reduce the manufacturing cost.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a first color region composed of a red filter and a second color region composed of a blue filter on a substrate. A third color region composed of a green filter, a red filter smaller in area than the filter in the first color region, a blue filter smaller in area than the filter in the second color region, and a filter in the third color region. And a fourth color region comprising a green filter having a small area. In this case, the ratio of the area of the red filter in the first color area, the area of the blue filter in the second color area, and the area of the green filter in the third color area is 1: 1: 1. It is preferable to do so.
It is preferable that the ratio of the area of the red filter, the area of the blue filter, and the area of the green filter in the fourth color region is 1: 1: 1.

On the other hand, the present invention relates to a liquid crystal device having a liquid crystal sandwiched between a pair of substrates provided with at least a transparent electrode and having pixels composed of at least four color regions partitioned from each other. A first color region in which four color regions are provided with a red filter to display red, and
A second color region in which a blue filter is provided to perform blue display, a third color region in which a green filter is provided to perform green display, and a red filter, a blue filter, and a green filter are provided together. This is a fourth color area for display. In this case, it is preferable that in the fourth color area, areas corresponding to the red, blue and green filters are simultaneously turned on to perform white display. The area of the first color region, the area of the second color region, and the third
It is preferable that the ratio of the areas of the color regions is 1: 1: 1. Furthermore, it is preferable that at least two of the shape of the first color region, the shape of the second color region, and the shape of the third color region are different from each other. Still further, the ratio of the area of the red filter corresponding to the first color region, the area of the blue filter corresponding to the second color region, and the area of the green filter corresponding to the third color region is: Preferably, the ratio is 1: 1: 1. The area of the fourth color area may be smaller than any of the area of the first color area, the area of the second color area, and the area of the third color area. . Further, it is preferable that the ratio of the area of the red filter, the area of the blue filter, and the area of the green filter in the fourth color region is 1: 1: 1. Still further, in the fourth color region, a red filter, a blue filter, and a green filter may be arranged apart from each other. Further, in the fourth color region, a red filter, a blue filter, and a green filter may be adjacent to each other, and display may be performed only through these three color filters. Further, the transparent electrodes of the pair of substrates may form a simple matrix structure. Still further, the distance between the pair of substrates is 3 microns or less.
You may do so. Further, the liquid crystal may be a liquid crystal exhibiting a chiral smectic phase. further,
The liquid crystal may be a liquid crystal exhibiting ferroelectricity.

In addition, based on the above configuration, color display of up to eight colors is performed by a combination of lighting of the first to third color areas. When the fourth color area is turned on, the intermediate colors are further displayed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the same parts as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 2 is a diagram showing an example of a plan configuration of a pixel of a liquid crystal display element (liquid crystal element) 10 on which a color filter substrate according to the present invention is mounted, as viewed from an observer side (color filter substrate side). is there.

The liquid crystal display element 10 according to the present embodiment
As shown in FIG. 2, four color regions (dots) 11R, 11B, and 11 for displaying red, blue, green, and white, respectively.
G, 11W are provided on a base material serving as a base, and a pixel 12 is constituted by a set of these four color regions 11R,.

Here, the above-described four color regions 11R,...
Among them, the first color area (dot) 11R is provided with a red filter 2R corresponding thereto to perform red display, and the second color area (dot) 11B corresponds thereto. Thus, a blue filter 2B is provided to perform blue display. The third color area (dot) 11G is provided with a green filter 2G corresponding to the third color area (dot) 11G to perform green display. These color filters 2R, 2B, 2G are preferably formed on the substrate such that their areas (planar areas) are substantially equal and the area ratio is 1: 1: 1. For example, each color filter 2R, 2B, 2G is
It is formed in a 00 μm square shape.

On the other hand, the fourth color region (dot) 11W has a red / blue / green color filter 3 corresponding thereto.
R, 3B, 3G are arranged together, and the color area 11W
Is preferably configured to display white by simultaneously lighting these three colors. Therefore, preferably, the red / blue / green color filters 3R, 3B,
The area of 3G is smaller than the area of each of the color filters 2R, 2B, 2G, and is set equal to each other. For example, specifically, any of the filters 3R,
... also has a rectangular shape with a length of 200 μm and a width of 50 μm,
The area ratio is set so as to be 1: 1: 1.

FIGS. 3A to 3C show another preferred example of the planar configuration of the pixel (when viewed from the observer side) in the liquid crystal display element 10 on which the color filter substrate according to the present invention is mounted.

In the examples shown in FIGS. 3A and 3B, each of the red, blue, and green colors is used as a color filter corresponding to the fourth color area 11W for displaying white, similarly to the example shown in FIG. Color filters 3R, 3B, 3G are spaced apart from each other and formed in stripes. In the example shown in FIG. 3C, fine color filters 3R, 3B, and 3G for red, blue, and green are adjacent to each other to correspond to the fourth color area 11W that performs white display. Are formed in a stripe shape.

In the liquid crystal display device of the above-described example, specifically, as described later, for example, a light-shielding material such as a metal is provided on the liquid crystal side of the color filter substrate through a flattening layer or a transparent electrode. Color filter 2
By providing a mask excluding portions corresponding to R, 2B, 2G and 3R, 3B, 3G, a color region where light is actually transmitted in each color through these color filters, that is, an actually effective color region 11R , 11B, 11G and 1
The part that can be 1 W is defined. Here, the color area 11
R, 11B and 11G may have different shapes,
In addition, it is preferable that the respective areas be the same. Regarding the color area (dot) 11W, the other color areas 11R, 11B and 1W are taken into consideration in view of the human eyes during multi-color display.
It is preferable to set the area smaller than 1G. As shown in FIGS. 2, 3 (a) and 3 (b), the color region 11W is formed from three color filters 3R, 3B, 3G and a transparent portion of the gap without a color filter, or FIG. As shown in (c), it can be formed only by three color filters (for three colors) 3R, 3B and 3G.

In the liquid crystal display device of the present invention as described above, a color region (dot) 11R for performing red display, a color region (dot 11B) for performing blue display, a color region for performing green display based on the configuration of the color filter and the like. (Dot) 1
It is characteristic in that a fourth color region 11W composed of fine color filters 3R, 3B and 3G for each of red, blue and green is provided in addition to 1G. Thus, compared to a case where a color region for displaying white is formed by providing a white (transparent) filter, red,
Due to the better film thickness controllability of the blue and green filters compared to the white filter, the film thickness step between the fourth color region and the other color regions is suppressed, and the flatness within the pixel is reduced. Is improved. In this case, considering that there is a possibility that the transmittance of the entire pixel is slightly reduced due to the use of the filter colored in the fourth color area, FIGS.
As shown in (c), the sizes of the color filters 3R, 3B and 3G corresponding to the fourth color area 11W are changed according to the required brightness as shown in FIGS. 3 (a) to 3 (c). By changing the transmittance, the transmittance of the fourth color region 11W in white display can be adjusted. In the case where brightness is required, for example, as shown in FIG. 3 (a), by increasing the gap between the color filters 3R, 3B and 3G, the transmitted light increases. However, in order to obtain white color, it is desirable that each area ratio is 1: 1: 1. When the gap is widened, flattening of the color filter and the gap portion in the fourth color region becomes a problem. However, according to the configuration of the present invention, between the colors, that is, the first, second, and third color regions, The difference in thickness from the fourth color region is reduced, and the flatness of the entire color filter is improved. That is,
A fourth region for performing white display in a state where 3R, 3B and 3G are separated from each other as compared with a case where a white region is formed by a W white filter having a different thickness distribution characteristic, thereby improving the overall flatness. .

The above-described color filters 2R, 2R,
, 3R,... Are formed on the surface of the glass substrate G, and form a large number of pixels 12, (FIG. 2 and FIG. 3 show only one pixel). The glass substrate G on which the color filters 2R,..., 3R,.
Is formed with a transparent electrode, an orientation control layer, and other functional layers as necessary, and then bonded to another glass substrate, and liquid crystal is injected into the gap between these substrates to form a liquid crystal display element. Is created.

FIG. 4 shows an example of a cross-sectional structure of the liquid crystal display device having the pixel configuration shown in FIG. 3B (a cross-sectional structure along the line aa 'in FIG. 3B).

In the structure shown in FIG. 1, first, a color filter 2R constituting a color region 11R and a color region 1 are formed on a transparent base material (substrate) 41 such as glass which is a base substrate.
The color filters 3R, 3B, and 3G that constitute 1W, and preferably have the same area as each other, are formed respectively.

These color filter patterns can be formed by various methods. For example, as described later, a photosensitive organic polymer film containing a coloring component of a predetermined color, for example, a polyamide or polyimide film is photolithographically formed. It can be formed by patterning by a method. On these color filters, a flattening layer 42 is formed to correct unevenness between the filters. The flattening layer 42 corrects a step between the color filters,
Further, any material may be used as long as it protects the color filter in the subsequent step and has heat resistance and chemical resistance. For example, polyamide, epoxy resin and organic silane resin are used.
Further, a light-shielding layer is preferably formed (not shown) between the pixels 12 formed of the color regions constituted by these color filters to prevent color mixture.

A barrier layer or the like is formed on the flattening layer 42 if necessary (not shown), and a transparent electrode 4 made of a transparent conductive material such as ITO is formed so as to correspond to a lower color filter layer.
4 are formed in a predetermined pattern.

Further, in order to reduce the resistance of the transparent electrode 44, an auxiliary electrode 45 is formed on the transparent electrode 44 in a predetermined pattern. In the example shown in FIG.
A color region that transmits light can be defined by the pattern (1). As a material of the auxiliary electrode 45, for example, Cr, Mo, Al
Alternatively, metal materials such as alloys thereof can be used.

On the transparent electrode 44 and the auxiliary electrode 45, if necessary, there is a layer for controlling the alignment state of the liquid crystal through a layer for preventing a short circuit with the counter substrate or improving other element functions. An orientation control layer 46 is formed. Orientation control layer 46
Various organic polymer films such as polyimides and polyamides and inorganic films were applied, and a uniaxial orientation treatment such as rubbing was performed as necessary.

On the other hand, an orientation control layer 56 is formed on a transparent substrate (substrate) 51 such as glass via a transparent electrode 54.

The substrates 41 and 51 are arranged to face each other via a spacer having a predetermined shape or an adhesive material (not shown), and a liquid crystal 47 is injected into a gap therebetween. , 54,... Constitute, for example, a simple matrix structure. The distance between the substrates depends on the applied liquid crystal and its mode.
By the spacer, for example, a chiral smectic liquid crystal to be described later is specified to have a size of 3 μm or less.

As the liquid crystal material 47, a chiral smectic liquid crystal exhibiting ferroelectricity, or a twisted nematic (TN) or super twisted nematic (STN) type liquid crystal material can be used.

In the liquid crystal display device of the above-described example, the fourth
Color filters 3R and 3B constituting the color region 11W
In 3G and 3G, the film thickness difference from the color filter 2G constituting another color region 11G is suppressed. Therefore, in the fourth color region 11W, the flatness within the device,
For example, the flatness of the alignment control layer 46 corresponding to the color region 11W is good, and the distance (cell gap) between both substrates in one pixel and in the element is uniformly maintained. Therefore, the configuration of the present invention is particularly preferable in a liquid crystal display element requiring a smaller cell gap, specifically, a liquid crystal display element requiring a cell gap of 3 μm or less. For example, it is particularly effective for a display element using a chiral smectic liquid crystal such as a liquid crystal exhibiting ferroelectricity.

In the liquid crystal display device of the present invention, for example, a simple matrix structure is applied, and color display can be performed by controlling the display (lighting) and non-display (non-lighting) state of each color region in one pixel. For this specific example,
This will be described in detail with reference to FIGS. 5 (a) and 5 (b).

FIG. 5A shows the substrate 4 in one pixel 12 of the liquid crystal display element having the structure shown in FIGS. 3B and 4 described above.
FIG. 5B shows an example of the arrangement of a transparent electrode, a color region and a color filter on one side, and FIG.
2 shows an example of the arrangement of transparent electrodes, color regions, and color filters on the base material 51 side in FIG. Note that the arrangement of the members in the drawing is all viewed from the liquid crystal side, and FIG.
The vertical axis direction (Y) in (a) matches the horizontal direction (X) in FIG. Also, the layers existing on the liquid crystal side from the transparent electrode are omitted. (For example, an auxiliary electrode pattern that defines a color area is omitted.) As shown in FIG. 5A, on the base material 41 side, the color filters 2R, 2B, 2G, and 3R, 3 in one pixel 12 are provided.
A transparent electrode 44 is commonly formed on B and 3G as a first electrode. On the other hand, as shown in FIG.
On the one side, in the pixel 12, the transparent electrodes 54R, 54B, 54G, and 54W correspond to the color filters 2R, 2B, 2G, and 3R, 3B, and 3G on the substrate 41 side.
Are formed as the second electrodes. Thus, the substrate 4
Each of the color regions 11R, 11B, 11G, and 11W is determined in a region where a predetermined portion of the transparent electrode corresponding to the lower color filter on one side intersects with the transparent electrode on the substrate 51 side. Here, when the transparent electrode 44 and the electrode 54R on the side of the base material 51 are selected, the color region 11R provided with the color filter 2R at the intersection thereof is displayed (lighted). When the transparent electrode 44 and the electrode 54W on the side of the base material 51 are selected, the intersection of the color filter 3 and the transparent electrode 44 is selected.
The color area 11W including R, 3B, and 3G enters a white display state by simultaneous display (lighting) of three colors. A combination of the display state and the non-display state of each color region in one pixel performs multicolor display in the pixel.

Next, an example of a method of manufacturing the color filters 2R,..., 3R,... In the above-described example will be described with reference to FIGS.

First, a photosensitive resin solution (PA-101 manufactured by Ube Industries, Ltd.) was applied over the entire surface of a glass substrate G having a thickness of 1.1 mm.
2) is applied by a spinner to form a photosensitive resin layer 15 (see FIG. 6A). This solution contains a polyamide resin as a main component, and for example, a red pigment is dispersed in the solution. Next, the glass substrate G on which the photosensitive resin layer 15 is formed is pre-baked at a temperature of 85 ° C. for only 10 minutes. Thereafter, exposure is performed using a photomask 16 (see FIG. 6B), and only desired portions 15a,... Of the photosensitive resin layer 15 are photo-cured (see FIG. 6C). Next, the photosensitive resin layer 15 is sprayed with a developing solution and is not photocured (portions other than 15a,...).
, And the larger color filters 2R,... And the smaller color filters 3R,... Are formed simultaneously (see FIG. 6D). .., 3B,... And a green filter 2G,
, 3G,... Are repeated to form the pixels 12,.

Next, the operation and effect of the above-described liquid crystal display device will be described.

According to the liquid crystal display device having the above-described configuration, a maximum of eight colors can be displayed by combining the lighting of the three color regions 11R, 11B, and 11G for displaying each color of red, blue, and green in one pixel. When the color area 11W for displaying white is turned on, the intermediate colors are further displayed, and the display quality of the color can be improved.

Further, according to the present embodiment, white display is achieved by simultaneously lighting the red filter 3R, the blue filter 3B and the green filter 3G. It is not necessary to use a filter. That is, since the filters 3R,... Of the three colors having substantially the same characteristics are used, the step between the filters is reduced, and flattening can be achieved. As a result, the inter-substrate distance (cell gap) and the like in the pixels of the liquid crystal display element 10 and between the pixels are made uniform, and the driving margin can be greatly improved. The liquid crystal display element 10 is formed, and the color filters 2R, 2R, in the color regions 11R, 11B, 11G are formed.
When measuring the level difference between the color filters 3R, 3B and 3G in the color regions 11W, 2B and 2G,
The step is 500 for a substrate of 300 × 350 mm size.
Å It was small below.

Further, three color filters 2R,.
, Including a white filter.
The number of times of patterning is reduced as compared with the case where a color filter is formed. As a result, the manufacturing process is simplified, the yield is improved, and material costs and manufacturing costs are reduced.

Further, by setting the area ratio of the red filter 3R, the blue filter 3B and the green filter 3G in the color region 11W to 1: 1: 1,
Appropriate white color is displayed by lighting of W.

[0042]

As described above, according to the present invention,
Since color display is performed by a combination of four colors of red, blue, green, and white, the number of colors displayed is larger than in the case of three colors of red, blue, and green, and the display quality of colors can be improved. it can.

Further, according to the present invention, white display is achieved by simultaneously lighting the red filter, the blue filter, and the green filter. Therefore, it is necessary to use a white filter having greatly different in-plane film thickness distribution characteristics. There is no. In other words, since filters of three colors having substantially the same characteristics are used, a step between the filters in one pixel is reduced, and flattening can be achieved. As a result, the driving margin of a liquid crystal element, particularly, a display element using a ferroelectric liquid crystal having a small distance between substrates can be greatly improved.

Further, since it is only necessary to form filters of three colors, the number of times of patterning is reduced as compared with the case of forming filters of four colors. As a result, the manufacturing process is simplified, the yield is improved, and material costs and manufacturing costs are reduced.

The area ratio of the red, blue and green filters in the fourth color region is set to 1:
When the ratio is set to 1: 1, white is displayed by lighting the color area.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of one pixel in a conventional liquid crystal display element.

FIG. 2 is a plan view illustrating a configuration of one pixel in one embodiment of a liquid crystal display element of the present invention.

FIGS. 3A to 3C are plan views showing the configuration of one pixel in various embodiments of the liquid crystal display device of the present invention.

FIG. 4 is a cross-sectional view showing the structure of the liquid crystal display element along the line aa ′ in FIG. 3 (b).

5 is a plan view showing the arrangement of transparent electrodes and color filters in pixels of the liquid crystal display element shown in FIG.

6A and 6B are schematic views showing a method for manufacturing a liquid crystal display element, particularly a method for manufacturing a color filter, wherein FIG. 6A is a view showing a state in which a photosensitive resin layer is formed on a glass substrate, and FIG. (C) is a diagram for explaining a state after the completion of the exposure process, (d) is a diagram for illustrating a state after the completion of the development process, and (e) is a diagram for illustrating a state after completion of the color filter. FIG.

[Explanation of symbols]

 2R red filter 2B blue filter 2G green filter 3R red color filter 3B blue color filter 3G green color filter 10 liquid crystal display element (liquid crystal element) 11R first color area 11B second color area 11G third color area 11W fourth Color region 12 pixels 41 transparent substrate (substrate) 44 transparent electrode 47 liquid crystal 51 transparent substrate (substrate) 54 transparent electrode G glass substrate

Claims (16)

(57) [Claims] 1. A first filter comprising a red filter on a substrate.
And a second color region comprising a blue filter,
A third color region composed of a green filter, a red filter smaller in area than the filter in the first color region, a blue filter smaller in area than the filter in the second color region, and a filter in the third color region. And a fourth color region comprising a green filter having a small area. 2. A ratio of an area of a red filter in the first color area, an area of a blue filter in the second color area, and an area of a green filter in the third color area is 1: 1. The color filter substrate according to claim 1, wherein: 3. The ratio of the area of the red filter, the area of the blue filter, and the area of the green filter in the fourth color region is 1: 1: 1. 2. The color filter substrate according to 2. 4. A liquid crystal device having a pixel including at least four color regions partitioned by interposing liquid crystal between a pair of substrates provided with at least a transparent electrode, wherein the four color regions in one pixel are provided. A first color region in which a red filter is provided to display red, a second color region in which a blue filter is provided to display blue,
A liquid crystal element comprising: a third color region in which a green filter is provided to perform a green display; and a fourth color region in which a red filter, a blue filter, and a green filter are provided to perform a display. . 5. The liquid crystal device according to claim 4, wherein, in the fourth color region, regions corresponding to a red filter, a blue filter, and a green filter are simultaneously turned on to perform white display. 6. A ratio of the area of the first color area, the area of the second color area, and the area of the third color area,
The liquid crystal device according to claim 4, wherein the ratio is 1: 1: 1. 7. The device according to claim 6, wherein at least two of the shape of the first color region, the shape of the second color region, and the shape of the third color region are different from each other. The liquid crystal element according to the above. 8. A ratio of an area of a red filter corresponding to the first color area, an area of a blue filter corresponding to the second color area, and an area of a green filter corresponding to the third color area. The liquid crystal element according to claim 4, wherein the ratio is 1: 1: 1. 9. The area of the fourth color area may be an area of the first color area, an area of the second color area, and an area of the third color area.
The liquid crystal device according to claim 4, wherein the area is smaller than any one of the areas of the color regions. 10. The method according to claim 5, wherein the ratio of the area of the red filter, the area of the blue filter, and the area of the green filter in the fourth color region is 1: 1: 1. Liquid crystal element. 11. The liquid crystal device according to claim 4, wherein a red filter, a blue filter, and a green filter are arranged apart from each other in the fourth color region. 12. The color filter according to claim 4, wherein a red filter, a blue filter, and a green filter are adjacent to each other in the fourth color region, and display is performed only through these three color filters. Liquid crystal element. 13. The liquid crystal device according to claim 4, wherein the transparent electrodes of the pair of substrates form a simple matrix structure. 14. The liquid crystal device according to claim 4, wherein a distance between the pair of substrates is 3 μm or less. 15. The liquid crystal device according to claim 4, wherein the liquid crystal is a liquid crystal exhibiting a chiral smectic phase. 16. The liquid crystal device according to claim 4, wherein the liquid crystal is a liquid crystal exhibiting ferroelectricity.