JP2003280000A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the shadow of rubbing causes an orientation defect and lowers display quality in a liquid crystal display device using a columnar spacer. <P>SOLUTION: The area of a green color layer is deformed to the area of the other color layer and the columnar spacer is installed at the deformed part. Thus, an accurate cell gap is supplied to the green pixel of the highest visual sensitivity, the shadow of rubbing is separated from the green pixel, and the liquid crystal display device of excellent display quality is realized. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device in which a liquid crystal cell gap is formed by columnar spacers.

[0002]

2. Description of the Related Art A liquid crystal display device has a structure in which liquid crystal is sealed between two substrates. In order to define a distance between the substrates, that is, a cell gap, a spacer such as plastic beads having a uniform particle diameter is conventionally used. It was scattered between the substrates. However, in such a method in which the spacers are randomly dispersed, the spacers located in the display area, that is, the pixels disturb the alignment of the liquid crystal to cause light leakage, or the structure such as wiring or color filters is formed in the substrate surface. If there is unevenness due to the above, there is a problem that the cell gap becomes non-uniform depending on the arrangement position of the spacer.

As a method for solving these problems, it has been proposed to form columnar spacers using a photoresist or the like. As a result, the positions of the spacers can be restricted to the outside of the display area (pixels) and the arrangement density can be made constant, so that light leakage and nonuniformity of cell gaps can be eliminated.

However, since the columnar spacers are usually required to have a height of several microns, when the alignment film is formed after the spacers have been erected and the rubbing alignment treatment is performed, the portions which are not rubbed by the protrusions of the spacers (that is, the shadow of the alignment). Occurs, and that portion becomes an alignment disorder region, which impairs display quality, which is a new problem.

To address this problem, for example, Japanese Unexamined Patent Application Publication No. Hei 9
According to Japanese Patent Laid-Open No. 73088, a spacer is arranged at a position where the shadow of the alignment with the spacer as a starting point does not reach the pixel region, and an alignment defect is caused within a range that does not affect the pixel by using wiring on the substrate or a black matrix. A solution to hold down is disclosed.

[0006]

However, in order to prevent the shadow of the orientation from the spacer as the starting point from reaching the pixel region, the position where the spacer is arranged is restricted. Since it is desirable to arrange it so that it does not affect the green pixel, which has particularly high visibility, the spacer should be placed away from the green color layer.
For example, it may be necessary to dispose it in the position of the blue color layer. In this case, the cell gap of the liquid crystal layer is determined by the thickness of the blue color layer and the thickness of the spacer. If the thickness of the blue color layer varies, the size of the cell gap also varies. As a result, there arises a problem that the optimum cell gap of the green pixel varies and the display characteristics change. Further, depending on the mode of the liquid crystal used, it is necessary to perform rubbing in a specific direction, and it may be difficult to arrange the spacer at a position where the shadow of the alignment does not reach the pixel region. For example, OCB (Optically Compensa)
In the case of the ted Birefringence mode,
It is desirable that the rubbing direction is the vertical direction of the screen in order to secure a wide viewing angle, and the IPS (InPla
In the case of (ne Switching) mode, the rubbing direction needs to be a direction slightly inclined from the vertical direction of the screen. Normally, three color layers of red, green, and blue are arranged in a vertical stripe pattern in the color layer, and in order to accurately define the cell gap in the green pixel having the highest visibility, the spacer is formed in the green color layer as shown in FIG. It is desirable to place it at the position. FIG. 9 shows one pixel unit (centering on a green pixel) of the active matrix array substrate including the TFT 12 used in the OCB liquid crystal mode, and the pixel electrode is formed in a region separated by the gate wiring 4 and the source wiring 5. 6 and the TFT 12 are formed. Further, stripe-shaped red, green, and blue color layers 8R, 8G, and 8B are formed for each pixel. The columnar spacers 10 are arranged on the gate wiring 4, but the rubbing direction is the vertical direction, that is, the direction of the source wiring 5. As a result, the shadow of the rubbing is cast on the green pixel electrode, and the display due to the misalignment occurs. The unevenness will be noticeable.

The present invention was devised in view of the inconveniences of the above-mentioned conventional liquid crystal display device, and in particular, in the OCB mode or IPS mode liquid crystal display device having excellent viewing angle characteristics, it is possible to secure a reliable cell gap and An object of the present invention is to provide a liquid crystal display device of high display quality, which eliminates the influence of the shadow of the spacer.

[0008]

A liquid crystal display device according to the present invention has a columnar spacer which keeps a constant distance and sandwiches a liquid crystal to face each other. On the side, there are provided at least gate wirings and source wirings arranged in a matrix, and pixel electrodes provided corresponding to respective intersections of the gate wirings and source wirings, and red, green, and blue color layers are provided for each pixel electrode. In a liquid crystal display device in which stripes are provided, the green color layer region is
Transform to the adjacent blue or red color layer area,
A columnar spacer is formed in the deformed green color layer portion.

This makes it possible to isolate the shadow of the rubbing of the columnar spacers from the green pixel having high visibility to suppress the influence on the display due to the alignment failure, and to provide an accurate cell gap for the green pixel. It has the effect of giving.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal display device of the present invention will be described below more specifically with reference to the drawings.

(Embodiment 1) FIG. 1 is a plan view showing the structure of one pixel on an active matrix array substrate in a liquid crystal display device according to Embodiment 1, and FIG. 2 shows a portion A-B in FIG. 1 (a). FIG. FIG. 1A shows a plan view of the configuration of the active matrix array on the first substrate 1, and FIG. 1B shows the first substrate 1.
And the red, green, and blue color layers 8R, 8 formed on the second substrate 2.
The state where G and 8B are overlapped is shown. As shown in FIGS. 1 and 2, in the liquid crystal display device of the present invention, the first substrate 1 and the second substrate 2 are opposed to each other, and the distance therebetween is defined by a columnar spacer 10. The liquid crystal layer 11 operates in the OCB mode. On the inner surface of the first substrate 1, the TFT 1 including the gate wiring 4, the gate insulating film 3, the semiconductor layer 7, the source wiring 5, and the pixel electrode 6 is formed.
An active matrix array including 2 is configured. On the inner surface of the second substrate 2, a striped color layer 8R,
8G and 8B, a black matrix 9 for light shielding, and a transparent counter electrode 16 made of ITO or the like are formed, and columnar spacers 10 that define a cell gap of liquid crystal are further formed thereon. Although not shown in the figure, an alignment film is further applied to these substrates, and rubbing alignment treatment is performed by rubbing the alignment film with a rubbing cloth or the like. The rubbing direction is set to be substantially parallel to the source wiring 5 on both substrates. This is because it is generally desired in liquid crystal display devices to secure good viewing angle characteristics in the left-right direction.
This is because the viewing angle characteristics of the CB mode liquid crystal are better in the direction perpendicular to the rubbing than in the rubbing direction (the direction in which the liquid crystal molecules bend). Note that FIG.
In order to avoid complication of the drawing, the semiconductor layer 7, the black matrix 9 and the like are not shown in (a) and (b). Also,
Actually, the surface of the active matrix array is covered with a protective insulating layer, but this is also omitted in the drawing for simplicity.

The point of the present invention lies in the shape of the green color layer 8G and the position where the columnar spacer 10 is installed. That is,
As shown in FIG. 1B, a part of the green color layer 8G is expanded and deformed toward the region of the red color layer 8R or the blue color layer 8B, and the columnar spacer 10 is expanded. The point is that it is formed in the region of the green color layer 8G.
With this configuration, the cell gap is first set to the correct value by surely being determined by the spacer thickness (height) for the green pixel with the highest visibility even if the thickness of each color layer varies. Since the columnar spacers 10 can be kept away from the green pixel electrode 6, the region of poor alignment due to rubbing shadows can be kept away from at least the green pixels. This makes it possible to realize a liquid crystal display device with stable display quality.

If the shape of the green color layer 8G is not changed, only the position of the columnar spacer 10 is separated from the green pixel, for example, a spacer is provided at the boundary between the green and blue color layers or in the region of the blue color layer 8B. When installed, the variation in the thickness of the blue color layer 8B directly becomes the variation in the cell gap of the green pixel, resulting in the variation in display quality.

In this example, the cross-sectional shape of the spacer has an elliptical shape that is long in the rubbing direction, so that the shadow of the rubbing is narrowed and the mechanical strength is maintained. In addition, the cross-sectional shape of the spacer may be a rectangle long in the rubbing direction. In the following examples, the cross-sectional shape of the spacer is shown as a circle for simplicity.

Although FIG. 1 shows an example in which the spacers are placed at the boundary between the green and red pixel regions, in FIG. 3, the green color layer 8G is enlarged toward the blue color layer 8B. An example of expanding and forming a spacer in the expanded region will be shown. In this configuration, the rubbing shadow of the spacer is present in the blue pixel, but blue has the lowest luminosity, so even if some misalignment exists, it is not noticeable.

Further, as an extension of the present invention, as shown in FIG. 4, the island 8G-a of the green color layer is formed near the boundary between the blue and red color layers separated from the green color layer 8G. However, the columnar spacer 10 can be installed there.

As described above, according to the present invention, the green color layer is formed so that the correct cell gap can be formed for the green pixel having the highest visibility and that the rubbing shadow of the spacer does not exist in the green pixel. The shape and the installation position of the spacer are devised. In these, the spacer is the gate wiring,
It is desirable to install the wiring in a wiring portion such as a source wiring, or in an element that shields light such as a black matrix. Further, as shown in FIG. It is desirable to devise so that the cell gap does not change even if the positions of the spacers slightly vary by widening or widening the width of the black matrix. In addition to this, in many cases, since the storage capacitance line is usually installed in parallel with the gate wiring, it is also effective to form a spacer on it. Further, as shown in FIG. 5, if the red, green, and blue color layers are formed in the same shape in consideration of the concept of the present invention, the mask for color layer processing can be shared. As shown in FIG. 6, when the color layer is not expanded except the position where the spacer of the green color layer is installed, even if the rubbing shadow is generated by the edge of the expansion area, the effect is not displayed. It is possible to prevent the entire spread.

(Second Embodiment) FIG. 7 is a sectional view of a liquid crystal display device according to a second embodiment. As shown in FIG. 7, in the second embodiment, elements (gate wiring 4, pixel electrode 6, TF) that form an active matrix are formed on the inner surface of the first substrate 1.
In addition to T12), color layers 8R, 8G, 8B, a black matrix 9 and columnar spacers 10 are formed.
It suffices to uniformly form the transparent counter electrode 16 on the second substrate 2.

In this case as well, the shape of the green color layer 8G is deformed and the columnar spacers 10 are installed in the deformed portion as in the first embodiment, and in such a structure as well. The effects of the present invention are exhibited similarly. By forming the color layer on the active matrix substrate side, the requirement for alignment accuracy between the first and second substrates is relaxed, and it is also effective for cost reduction.

Although the liquid crystal display mode is the OCB mode in the above embodiment, the IPS shown in FIG.
Even in the mode, the display quality can be stabilized by applying the same configuration. In the case of using the IPS mode, the pixel electrode 6 and the common counter electrode 13 are provided on the first substrate so as to face each other, and the rubbing alignment process is performed in a direction slightly inclined from the direction parallel to them. The color layer and the columnar spacer may be installed on the first substrate or the second substrate.

The configurations of the active matrix shown in FIGS. 2 and 7 are merely examples, and the present invention is not limited to this structure.

[0022]

As described above, according to the present invention, a columnar spacer is used to realize an accurate cell gap, and
A liquid crystal display device with high display quality can be provided by suppressing the influence of alignment failure caused by the shadow of rubbing.

[Brief description of drawings]

FIG. 1A is a view of a liquid crystal display device 1 according to a first embodiment.
Plan view showing an electrode configuration of a pixel (b) Plan view including the same color layers

FIG. 2 is a sectional view of a portion AB in FIG. 1A of the first embodiment.

FIG. 3 is a plan view showing an electrode configuration of one pixel showing another configuration example in the liquid crystal display device of the first embodiment.

FIG. 4 is a plan view showing an electrode configuration of one pixel representing still another configuration example in the liquid crystal display device of the first embodiment.

FIG. 5 is a plan view showing an electrode configuration of one pixel representing still another configuration example in the liquid crystal display device of the first embodiment.

FIG. 6 is a plan view showing an electrode configuration of one pixel representing still another configuration example in the liquid crystal display device of the first embodiment.

FIG. 7 is a cross-sectional view of one pixel showing the configuration of the liquid crystal display device according to the second embodiment.

FIG. 8 is a plan view showing an electrode configuration when the present invention is applied to an IPS mode liquid crystal display device.

FIG. 9 is a plan view showing an electrode configuration of one pixel in a conventional liquid crystal display device.

[Explanation of symbols]

1 First substrate 2 Second substrate 3 Gate insulation film 4 gate wiring 5 Source wiring 6 pixel electrodes 7 Semiconductor layer 8 color layers (red: 8R, green: 8G, blue: 8B) 9 Black matrix 10 Column spacer 11 Liquid crystal layer 12 TFT 13 Common counter electrode 16 Transparent counter electrode

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/30 338 G09F 9/30 338 9/35 9/35 (72) Inventor Hiroshi Shimano Kadoma City, Osaka Prefecture Daiji Kadoma 1006 Matsushita Electric Industrial Co., Ltd. F-term (reference) 2H089 LA09 LA12 QA05 QA15 TA02 TA04 TA12 TA13 2H090 KA07 KA18 LA01 LA02 LA15 MA07 MB01 2H091 FA02Y FA35Y FD04 GA02 GA06 GA08 HA09 HA18 LA16 2H092 GA04 GA02 GA02 GA14 GA23 QA09 QA18 5C094 AA03 BA03 BA43 BA46 CA19 DA13 EC03 FA01 FB15 HA08

Claims (12)

[Claims] 1. A gate wiring arranged in a matrix on a facing surface side of a first substrate among first and second substrates facing each other with a liquid crystal sandwiched therebetween by keeping a constant distance by a columnar spacer. A liquid crystal display device including at least a source wiring, pixel electrodes provided corresponding to the intersections of the gate wiring and the source wiring, and red, green, and blue color layers provided in stripes for each pixel electrode. 2. A liquid crystal display device according to claim 1, wherein a region of the green color layer is deformed toward an adjacent region of the blue or red color layer, and a columnar spacer is formed in the deformed green color layer portion. 2. The liquid crystal display device according to claim 1, wherein the columnar spacer is formed in a region where a gate wiring or a source wiring exists. 3. The liquid crystal display device according to claim 2, wherein the shape of the region of the gate wiring or the source wiring in which the columnar spacer is formed is modified. 4. The liquid crystal display device according to claim 1, wherein the color layer is formed on the first substrate. 5. The liquid crystal display device according to claim 1, wherein the color layer is formed on the second substrate. 6. The rubbing orientation treatment is performed on the substrate in a direction substantially parallel to the source wiring.
6. The liquid crystal display device according to any one of 5 to 5. 7. The liquid crystal display according to claim 6, wherein the installation position of the columnar spacer is such that the shadow of the columnar spacer in the rubbing alignment treatment does not cover the pixel electrode corresponding to the green color layer. apparatus. 8. A green color layer region is cut into a part of an adjacent blue or red color layer region to form an island shape, and a columnar spacer is formed on the island-shaped green color layer portion. It formed, The liquid crystal display device in any one of Claims 1-7. 9. The liquid crystal display device according to claim 1, wherein the green, blue and red color layers have the same shape. 10. The liquid crystal display device according to claim 1, wherein the width of the black matrix is larger than that of the columnar spacer. 11. The cross-sectional shape of the columnar spacer is elongated in the direction of the rubbing alignment treatment.
11. The liquid crystal display device according to any one of 10. 12. The liquid crystal mode is OCB or IPS
The liquid crystal display device according to claim 1, wherein: