JPH11212074A - Multi-gap color liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent display unevenness due to unevenness of cell thickness. SOLUTION: The external size of a blue filter 15b is set so small that it does not overlap with a source bus 6 and a gate bus 7 surrounding an opposite pixel electrode 8, and the external size of a green filter 15g is set so large that it overlaps with a couple of source buses 6 and a couple of gate buses 7 surround the opposite display electrode 8. Further, the distance d1 between the green filter 15g and both the buses 6 and 7 and the distance d2 between the blue filter 15b and pixel electrode 8 are set nearly equal to each other. The effective area (hatched area) of a spacer having the least cell thickness becomes much wider than before corresponding to the distances d1 and d2 and spacers arranged in the area can support an TFT array substrate 1 and a common electrode substrate 2 more stably than before.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-gap color liquid crystal display device, and more particularly, to prevention of display unevenness caused by uneven thickness of a liquid crystal cell.

[0002]

2. Description of the Related Art In a color liquid crystal display (hereinafter referred to as LCD), as shown in FIG. 3, an active matrix type TFT array substrate 1 using TFTs (thin film transistors) and a common electrode substrate 2 are arranged close to each other. Then, a liquid crystal (layer) 3 is sealed therebetween. In the TFT array substrate 1, a column-shaped source bus 6 and a row-shaped gate bus 7 intersect with each other to form a mesh, and the projecting surfaces of the source bus 6 and the gate bus 7 (hereinafter also referred to as both buses). Are arranged on substantially the same plane, and the pixel electrode 8 is provided in each mesh formed by both buses.
Are formed much thinner than both buses, and a TFT 9 is formed around each mesh corresponding to the pixel electrode 8 (FIG. 4B).

The TFT 9 is turned on when a scanning gate voltage is applied to the gate bus 7, and electric charges based on a video signal applied to the source bus 6 are formed between the pixel electrode 8 and a common electrode described later. It is stored in the pixel capacitance. FIG. 3B shows an aa ′ cross section of FIG. 3A, and a bb ′ cross section of FIG.
FIGS. 4A, 4B and 4C show cross sections c 'and dd', respectively. In each of these sectional views, the dimensions are appropriately enlarged. The source bus 6 is provided with an IT to improve its conductivity.
It has a three-layer structure of O, Mo and Al, and its protruding surface is almost the same height as that of the gate bus 7. In the place where both buses 6 and 7 are cross, as shown in detail in FIG. 4C, the source bus 6 is formed thin, the gate bus 7 is formed via an insulating film (S _i N _x) 11 thereon , The gate bus 7 is not particularly high at the intersection. As can be seen from FIG. 4C, a gap is created between the two buses, but is omitted in FIG.

In the common electrode substrate 2, a black matrix 14 is formed on the inner surface of the glass substrate 13 in a mesh shape facing the meshes of the TFT array substrate 1. For each mesh of the black matrix 14, R, G, and B color filters (also referred to as color filters) 15 are formed so as to be isolated from each other with a gap therebetween. A common electrode 16 is formed on the entire surface of the glass substrate 13 on which the color filter is formed.

[0005] There are various types of color filters 15, and here, types having different thicknesses for each of R, G, and B are used. In this type of color filter, the transmitted light intensity of the liquid crystal cell differs depending on the wavelengths of R, G, and B. Therefore, the thickness of the color filter is changed for each of R, G, and B for the purpose of correcting this. That is, R, G,
Assuming that the thickness of the color filter of each color B is tr, tg, tb, tb>tg> tr is set. As a result, the LCD using this color filter has a liquid crystal cell thickness of R,
It depends on G and B, and is called a multi-gap structure.

[0006] Other multi-gap color LCDs have other LCs.
As in the case of D, if the thickness of the liquid crystal cell is uneven, display unevenness occurs and visibility is reduced. Therefore, in the LCD, before the two substrates are bonded together, uniform spacers (not shown) having a uniform particle size are uniformly spread on the TFT array substrate 1 or the common electrode substrate 2 and then the liquid crystal is sealed by bonding. ing. The thickness of the liquid crystal cell is defined by the spacer.

[0007]

In a multi-gap color LCD, since the cell thickness is different for each of R, G, and B colors, all the uniformly dispersed spacers function effectively to define the liquid crystal cell thickness. Not necessarily. That is, FIG.
As shown in (2), on the inner surface of the common electrode substrate 2, the blue filter 15b is formed thicker than the red filter 15r and the green filter 15g, and protrudes above the blue filter 15b. On the inner surface of the common electrode substrate, both buses 6 and 7 project most. As a result, the cell thickness d of the region where the blue filter 15b and the buses 6 and 7 overlap, that is, the region hatched in FIG.
Is thinnest, and the glass substrates 1 and 2 are supported only by the spacers dispersed in this region. The effective area of the hatched spacer is very small in the area of each of the substrates 1 and 2. Since the spacer may move, if the effective area is small, the cell thickness cannot be stably maintained, and the cell thickness becomes uneven, which causes display unevenness.

An object of the present invention is to increase the effective area of a spacer in a liquid crystal cell, stably maintain the cell thickness, eliminate the cell thickness unevenness, and prevent display unevenness.

[0009]

(1) According to the first aspect of the present invention, the blue filter has a smaller outer shape so as not to overlap with both buses surrounding the opposing pixel electrodes, and the green filter defines the opposing pixel electrodes. When the outer shape is enlarged so as to overlap with a pair of surrounding source buses and a pair of gate buses, and a distance between the green filter and the two buses facing each other is d1, and a distance between the blue filter and the pixel electrode facing each other is d2, d1 ≒
The film thickness of both buses and the thicknesses tg and tb of the green and blue filters are set so as to be d2.

(2) In the invention according to claim 2, (1)
In, the outer dimensions of the red filter are set equal to the blue filters. (3) In the invention of claim 3, in the above (1), the red filter is formed close to the blue filter and the green filter, and the area thereof is set larger than that of the blue filter.

[0011]

1 and 2 show an embodiment of the present invention.
3, the same reference numerals are given to the portions corresponding to those in FIG. 3, and the duplicate description will be omitted. According to the first aspect of the present invention, the blue filter 15
b has a small outer dimension so as not to overlap with both buses 6 and 7 surrounding the pixel electrode 8 facing each other. Further, the green filter 15g is provided with a pair of source buses 6 surrounding the opposing pixel electrodes 8.
The external dimensions are formed large so as to overlap with the pair of gate buses 7.

Here, the green filters 15g facing each other
Assuming that the distance between the blue filter 15b and the pixel electrode 8 is d2, the distance between the blue filter 15b and the pixel electrode 8 is d1.
The thicknesses of both buses 6 and 7 and the thicknesses tg and tb of the green and blue filters are set so that ≒ d2. In this way, the effective area of the spacer having the smallest cell thickness is the area hatched in FIG. 1A. That is, a first area where the green filter 15g and the buses 6 and 7 overlap, and a second area where the blue filter 15b and the pixel electrode 8 overlap. However, since the thickness of the pixel electrode 8 is sufficiently smaller than the distance d2, the second region may be referred to as a region where the blue filter 15b exists. It can be seen that these hatched areas are considerably larger in area than the effective areas hatched in FIG. In the example of FIG. 1, the red filter 15r has the same outer dimensions as the blue filter 15b. In this way, there is an advantage that the masks used in the manufacturing process of the blue filter 15b can be used without preparing dedicated masks in the manufacturing process of the red filter 15r.

However, if the outer shape of the red filter 15r is the same as that of the blue filter 15b, a relatively large depression 20 appears on the black matrix 14 between the adjacent blue filter 15b and red filter 15r, and the TFT array substrate 1 or The spacers uniformly distributed on the common electrode substrate 2 move and easily accumulate. If the spacers accumulate in the depressions 20, display irregularities may appear. Therefore, in the invention of claim 3, the depressions 20 are formed by extending the outer shape of the red filter 15r to the vicinity of the blue filter 15b as shown in FIG. I try not to. As a result, the red filter 15r
Is closer to the blue filter 15b as well as the green filter 15g and has an area larger than that of the blue filter 15b.

[0014]

According to the present invention, the outer dimensions of the blue filter 15b are set small so as not to overlap with the source bus 6 and the gate bus 7 surrounding the pixel electrodes 8 facing each other, and the outer dimensions of the green filter 15g are set opposite to the display electrodes. 8 is set large so as to overlap with a pair of source buses 6 and a pair of gate buses 7 surrounding the pair. Since the distance d1 between the green filter 15g and the buses 6 and 7 and the distance d2 between the blue filter 15b and the pixel electrode 8 are set substantially equal, the distances d1 and d
2, the effective area of the spacer having the thinnest cell thickness becomes considerably wider than before, and the TFT array substrate 1 and the common electrode substrate 2 are supported more stably by the many spacers arranged in the effective area. Thus, display unevenness caused by uneven cell thickness can be prevented.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of claim 1, wherein A is a plan view, and B is
2 is a sectional view taken along line aa ′ of FIG.

FIG. 2 is a view showing an embodiment of claim 2, wherein A is a plan view, and B is
2 is a sectional view taken along line aa ′ of FIG.

FIG. 3 is a view showing a conventional LCD, wherein A is a plan view and B is A
Aa ′ sectional view of FIG.

4A is a sectional view taken along line bb 'of FIG. 3, and FIG.
3 is a sectional view taken along the line c ′, and FIG.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Leaheim United States 85308 Glendale, Arizona, North Sixty Nines Avenue, 18863 (72) Inventor Takao Undai 4-3-1 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Philips Display Co., Ltd. (72) Inventor Masahiro Yoshiga 4-3-1, Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Hoshiden Philips Display Co., Ltd. (72) Inventor Kazuki Tamoka 4-chome, Takatsukadai, Nishi-ku, Hyogo Prefecture 3-1 Hosiden Phillips Display Co., Ltd.

Claims (3)

[Claims] 1. A source bus and a gate bus (hereinafter, referred to as both buses) are formed on an inner surface of a glass substrate so as to intersect with each other in a mesh shape, and protruding surfaces of both buses are arranged on substantially the same plane. A TFT array substrate in which pixel electrodes are formed considerably thinner than the buses in each mesh formed by both buses, and TFTs (thin film transistors) are formed around the meshes in correspondence with the pixel electrodes; On the inner surface of the substrate, a black matrix composed of a thin film is formed in a mesh shape corresponding to each mesh of the TFT array substrate.
Green and blue color filters are formed separately from each other, and the thicknesses tr, tg and tb of the respective color filters are t
r <tg <tb, and a common electrode substrate formed by forming a common electrode on the entire inner surface of the glass substrate on which the color filters are formed. The TFT array substrate and the common electrode substrate form a spacer. In a multi-gap color liquid crystal display device in which a liquid crystal is sealed between the two substrates, the blue filter has an outer shape so as not to overlap with the buses surrounding the pixel electrodes facing each other. The green filter has a larger outer shape so as to overlap a pair of source buses and a pair of gate buses surrounding the opposing pixel electrodes, and has a distance d1 between the opposing green filter and the two buses, and When the distance between the blue filter and the pixel electrode facing each other is d2, the thickness of both buses and the thickness t of the green and blue filters are set so that d1 ≒ d2. A multi-gap color liquid crystal display device wherein g and tb are set. 2. The multi-gap color liquid crystal display device according to claim 1, wherein an outer dimension of the red filter is set to be equal to that of the blue filter. 3. The method according to claim 1, wherein the red filter is:
A multi-gap color liquid crystal display device, which is formed close to the blue filter and the green filter, and has an area larger than that of the blue filter.