JP2000056307A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the liquid crystal display device which has a high aperture rate by having an area where alignment is disordered at a non-display part. SOLUTION: A liquid crystal layer 11 is interposed between a couple of substrates 1 and 2, many pixel electrodes 5 are formed in matrix on the opposite surface of the substrate 2 at given intervals, and a common electrode 6 is formed on the opposite surface of the other substrate 1. On the pixel electrodes 5, a 1st alignment control layer 7 in a projection shape having a slope surface from on a light shield film 12 sectioning adjacent two pixel electrodes 5 to the outside end edges of the adjacent pixel electrodes 5 is formed. On the common electrode 6, a 2nd alignment control layer 8 in a recessed shape complying with the protrusion of the 1st alignment control layer 7 is formed opposite the protrusion of the 1st alignment control layer 7. On the 1st and 2nd alignment control layers 7 and 8, alignment layers 9 and 10 are formed, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device of a split alignment type capable of displaying bright and high definition.

[0002]

2. Description of the Related Art As a recent liquid crystal display device, a liquid crystal display device having a wider viewing angle than a commonly used TN type liquid crystal display device has been used. The most frequently used one is a liquid crystal split alignment system. FIG. 12 to FIG. 14 show such an example, and such a split alignment liquid crystal display device has a pair of transparent substrates 101 and 102 made of glass which are vertically opposed to each other, and a sealing member ( (Not shown), and polarizing plates 103 and 104 outside of both transparent substrates. On the outer and inner sides of the transparent substrates 101 and 102, mountain-shaped alignment control films 107 and 108 made of resin, transparent electrodes 105 and 106 made of ITO, and alignment films 109 and 110 are laminated on these electrodes. Note that these alignment films 109 and 110 are not shown in FIG.

[0003] The transparent electrode 106 is composed of a large number of pixel electrodes arranged in a matrix.
Are defined by the black mask 112, respectively. The other electrode 105 is a common electrode. FIG. 13 shows a state in which no voltage is applied to the electrodes 105 and 106, and the liquid crystal molecules 111a in the liquid crystal layer 111 are in a state of standing between the pair of substrates. On the other hand, FIG.
6 shows a state where a voltage is applied to the liquid crystal layer 11.
The liquid crystal molecules 111a in 1 are tilted by the alignment controlled by the alignment films 107 and 108.

[0004]

In the liquid crystal divided alignment wide viewing angle liquid crystal display device shown in FIG. 12 to FIG. 14, since one pixel electrode 106 has two divided alignment regions by the alignment control film 108. The viewing angle dependency in the pixel is averaged, and a wide viewing angle display can be realized.However, since the alignment is disturbed at the boundary between adjacent divided alignment regions, light leakage occurs. A black mask must be provided at a position facing the above-mentioned alignment disorder. As a result, the aperture ratio of the pixel portion is reduced, and the display becomes dark. In particular, in the case of high definition display, the pixel aperture ratio may be considerably reduced. The present invention has been made in view of these problems, and an object of the present invention is to provide a liquid crystal display device having a high aperture ratio by arranging the above-mentioned region in which alignment is disturbed in a non-display portion.

[0005]

In the liquid crystal display device according to the present invention, a liquid crystal layer is interposed between a pair of substrates, and a large number of pixel electrodes are arranged in a matrix at predetermined intervals on the opposing surface of one of the pair of substrates. And forming a common electrode on the opposing surface of the other substrate, and, on the plurality of pixel electrodes, from the light-shielding film defining the space between two adjacent pixel electrodes to the outer edges of the adjacent pixel electrodes. The first alignment control film having a convex shape having an inclined surface directed toward the first electrode is formed, and a concave shape having an outer shape adapted to the convex shape is formed on the common electrode at a position facing the convex portion of the first alignment control film. Forming a second orientation control film of
An alignment film is formed on each of the second and second alignment control films.

In the structure of the present invention, the liquid crystal is divided and aligned between adjacent pixel electrodes, that is, one pixel electrode has only one alignment region. Therefore, since alignment disorder does not occur in the pixel electrode region, a light-shielding film serving as a black mask may be provided not between the common electrode of the opposing substrate but between the pixel electrodes in the conventional manner. The corner can be enlarged. Therefore, the present invention overcomes the conventional problem of a low aperture ratio by providing a division boundary line of the alignment domain in a portion other than the display pixel electrode, and can obtain a high-definition, wide viewing angle, and bright liquid crystal display device. .

In the liquid crystal display device according to the present invention, a first alignment control film over two adjacent pixel electrodes and a first alignment control film over at least two pixel electrodes adjacent to a pair of adjacent pixel electrodes at least in parallel. And may be formed by connecting these tops. In such a structure, it is easier to manufacture than to separately manufacture the first alignment control film over two adjacent pixel electrodes.

Further, in the liquid crystal display device according to the present invention, a liquid crystal layer is interposed between a pair of substrates, and a large number of pixel electrodes are formed in a matrix at predetermined intervals on a facing surface of one of the pair of substrates. A common electrode is formed on the opposing surface of the other substrate, and on the plurality of pixel electrodes, from the intersection of two light-shielding films defining four adjacent pixel electrodes to the outer edge of each pixel electrode. While forming a convex first alignment control film having an inclined surface toward the surface, the common electrode has an outer shape conforming to the convex shape at a position facing the convex portion of the first alignment control film. Forming a concave second alignment control film,
An alignment film may be formed on each of the first and second alignment control films. In such a liquid crystal display device, similarly to the above-described liquid crystal display device, the liquid crystal is divided and aligned between adjacent pixel electrodes, that is, one pixel electrode has only one alignment region. Therefore, since alignment disorder does not occur in the pixel electrode region, a light-shielding film serving as a black mask is provided not between the common electrode but between the pixel electrodes in the conventional manner, and the viewing angle is increased without lowering the aperture ratio. be able to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the liquid crystal display device according to the present invention will be described with reference to the drawings. The active matrix type liquid crystal display device according to the first embodiment is
As shown in FIG. 1 to FIG. 3, a pair of transparent substrates 1 and 2 made of glass arranged vertically facing each other, a liquid crystal layer 11 sealed between them by a sealing body, It comprises polarizing plates 3 and 4. A large number of pixel electrodes 5 are defined on the inner surface of the lower substrate 2 by a light-shielding film 12 such as a black matrix, are formed in a matrix at predetermined intervals, and are turned on and off by switching elements (not shown). It has become so. A common electrode 6 is formed on the opposite surface of the other substrate.

On a large number of pixel electrodes 5, adjacent two
A convex first alignment control film 7 having a gentle inclined surface 7a is formed on the light-shielding film 12 between the two pixel electrodes 5 and 5 toward the outer edges of these adjacent pixel electrodes. The inclination angle of the inclined surface 7a with respect to the electrode surface is 0.2 degrees to 5 degrees.
Degrees, preferably about 1 degree. On the other hand, a concave second alignment control film 8 having an outer shape corresponding to the convex shape is formed on the common electrode 6 at a position facing the convex portion of the first alignment control film 7. Orientation films 9 and 10 (not shown in FIG. 1) are formed on the first and second orientation control films 7 and 8, respectively.

The first orientation control film 7 is formed as follows. For example, the size (width × length) of the pixel electrode 5 is 46 μm
When the space between pixels is 10 μm, a 2 μm thick film of a photosensitive material is applied on the glass substrate 2 by a spin coater, prebaked at 90 ° C. for 2 minutes, and then subjected to a gradation mask (transmission method). Exposure is performed using a mask whose rate changes stepwise, the transmittance repetition cycle is 138 μm, corresponding to two pixels in the pixel vertical direction), and then developed. Thereafter, the remaining photosensitive agent is hardened by post-baking (200 ° C./60 minutes). After that, a flattening film having a thickness of 1 μm is again applied with a flattening material by a spin coater, and prebaked (80 ° C./1 minute),
By performing post-baking (180 ° C./60 minutes), the step-like portion on the surface is made a flat inclined surface, and the first orientation control film 7 is formed. Similarly, a second orientation control film 8 can be formed. Then, a vertical alignment agent is applied to a thickness of 1000 ° to form alignment films 9 and 10.
To form

[0012] The first pixel electrode straddling the two adjacent pixel electrodes 5, 5.
The alignment control film 7 has a color filter R (not shown).
(Red), G (Green), and B (Blue) are formed so as to straddle pixel electrodes of the same color. That is, it is formed so as to extend over the R pixel electrodes, the G pixel electrodes, or the B pixel electrodes. In that case, there is no color mixing due to the average of the transmittance between pixels. In such a liquid crystal display device, when no electric field is applied as shown in FIG. 2, the liquid crystal molecules 11a in the liquid crystal layer 11 are vertically aligned with respect to the respective inclined surfaces of the alignment films 9, 10. Since the boundary portions of the respective tilt alignment domains are all arranged in regions other than the pixel electrode 5 and the light-shielding film 12 is provided in those portions, there is no need to worry about light leakage due to disorder in alignment.

When an electric field is applied, the electric field is applied in a direction perpendicular to the substrate surface as shown in FIG.
It falls in different directions depending on the direction of the 0 slope. In this way, a divided orientation between pixels is realized, and the viewing angle characteristics are averaged between adjacent pixels. There is almost no concern that the definition from an angle will be reduced by the average between pixels. In FIG. 5, which shows the relationship between the viewing angle and the effective pixel pitch in the liquid crystal display device, when the display surface of the liquid crystal display device is viewed obliquely, the effective pixel density tends to increase.
In other words, while the oblique visibility is the same as before,
The aperture ratio increases.

When this liquid crystal display device performs 1024 × 708 XGA display using a TFT driving method,
Since the split orientation is performed with respect to the vertical viewing angle, the viewing angle (the vertical viewing angle of 50) is almost the same as the conventional split orientation in the pixel.
Degree) was obtained. On the other hand, the aperture ratio is remarkably improved to 40% in this liquid crystal display device from the conventional in-pixel division method shown in FIGS. In the device, it improved to 3.3%.

Next, a second embodiment of the liquid crystal display device according to the present invention will be described with reference to FIGS. The first embodiment shown in FIGS. 1 to 3 is an example in which the first alignment control film 7 and the second alignment control film 8 are formed independently for each of two adjacent pixel electrodes 5 and 5. However, in the second embodiment shown in FIGS. 5 to 7, since the first alignment control film and the second alignment control film are formed in series, the second embodiment shown in FIGS. 1 to 3 are denoted by the same reference numerals, and description of these members will be omitted.

In the second embodiment, adjacent pixel electrode pairs 5,
5 extend in the column direction adjacent to each other in parallel, and form a first alignment control film 17 so as to straddle two pixel electrodes. The second orientation control film 18 is also formed in a concave shape in accordance with the convex shape of the first orientation control film 17. In FIG. 5, the alignment films 9 and 10 formed on the first and second alignment control films 17 and 18 are not shown. FIG. 6 shows a cross section along the light shielding film 12 between the adjacent electrodes 5 and 5 in this liquid crystal display device when no voltage is applied, and FIG. 7 shows a cross section along the adjacent direction of the adjacent electrodes 5. . In this liquid crystal display device, the same operation and effect as those of the first embodiment were obtained.

Next, a third embodiment of the liquid crystal display device according to the present invention will be described with reference to FIGS.
This embodiment is different from the first embodiment shown in FIGS. 1 to 3 in that a first alignment control film and a second alignment control film are formed over four adjacent pixels. Therefore, in FIGS. 8 to 11, the same members as those in FIGS. 1 to 3 are denoted by the same reference numerals, and description of these members will be omitted.

In the third embodiment, the inclined surfaces 27 a, 27 b, 2 a from the intersection of the two light-shielding films 12 defining four adjacent pixel electrodes 5 to the outer edge of each pixel electrode 5 are formed.
While the convex first alignment control film 27 having 7c and 27d is formed, the external shape conforming to the convex shape is formed on the common electrode 6 at a position facing the convex portion of the first alignment control film 27. A second alignment control film 28 having a concave shape is formed. In addition,
In FIG. 8, the first and second alignment control films 27, 28
The alignment films 9 and 10 formed thereon are not shown.

FIG. 10 is a cross-sectional view taken along the line XX of FIG. 8 along the vertical light-shielding film 12 between the adjacent electrodes 5 and 5 in this liquid crystal display device when no electrode is applied. 11 is a cross-sectional view taken along the line XI-XI of FIG. 8 along the lateral light-shielding film 12 between the adjacent electrodes 5 and 5. In this liquid crystal display device, the same operation and effect as those of the first embodiment were obtained.

[0020]

As described above, the liquid crystal display device according to the present invention can avoid the influence on the aperture ratio and transmittance due to the disturbance of the liquid crystal alignment near the divisional alignment boundary line while realizing a wide viewing angle. Thus, a liquid crystal display device having a high aperture ratio, bright, and a wide viewing angle could be obtained.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display device shown in FIG. 1, taken along line II-II.

FIG. 3 is a cross-sectional view showing a state where a voltage is applied to the liquid crystal display device shown in FIG.

FIG. 4 is a graph showing a relationship between a viewing angle and an effective pixel pitch in the liquid crystal display device shown in FIG.

FIG. 5 is a partially cutaway perspective view showing a liquid crystal display device according to a second embodiment of the present invention.

6 is a cross-sectional view of the liquid crystal display device shown in FIG. 5, taken along the line VI-VI.

7 is a cross-sectional view of the liquid crystal display device shown in FIG. 5, taken along line VII-VII.

FIG. 8 is a partially cutaway perspective view showing a third embodiment of the liquid crystal display device according to the present invention.

9 is a partially cutaway perspective view showing a pixel electrode substrate of the liquid crystal display device shown in FIG.

FIG. 10 is a cross-sectional view of the liquid crystal display device shown in FIG. 8, taken along line XX.

11 is a cross-sectional view of the liquid crystal display device shown in FIG. 8, taken along line XI-XI.

FIG. 12 is a partially cutaway perspective view showing a conventional liquid crystal display device.

FIG. 13 is a cross-sectional view of the liquid crystal display device shown in FIG.
It is sectional drawing along the I line.

14 is a cross-sectional view showing a state where a voltage is applied to the liquid crystal display device shown in FIG.

[Explanation of symbols]

 1, 2 substrate 3, 4 polarizing plate 5 pixel electrode 6 common electrode 7 first alignment control film 8 second alignment control film 9, 10 alignment film 11 liquid crystal layer 12 light shielding film

Claims (3)

[Claims] 1. A liquid crystal layer is interposed between a pair of substrates, and a large number of pixel electrodes are formed in a matrix at predetermined intervals on a surface facing one substrate of the pair of substrates. Form a common electrode and, on the plurality of pixel electrodes, a convex first surface having an inclined surface extending from a light-shielding film defining between two adjacent pixel electrodes to an outer edge of the adjacent pixel electrodes. On the other hand, while forming the alignment control film, a concave second alignment control film having an outer shape conforming to the convex shape is formed on the common electrode at a position facing the convex portion of the first alignment control film. And an alignment film formed on each of the first and second alignment control films. 2. The method according to claim 1, wherein the first alignment control film extends over two adjacent pixel electrodes, and the first alignment control film extends over at least two pixel electrodes adjacent to the adjacent pixel electrode pair at least in parallel. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is formed continuously. 3. A liquid crystal layer is interposed between a pair of substrates, a large number of pixel electrodes are formed in a matrix at predetermined intervals on a surface facing one substrate of the pair of substrates, and a plurality of pixel electrodes are formed on a surface facing the other substrate. Form a common electrode and, on the plurality of pixel electrodes, a convex shape having an inclined surface extending from an intersection of two light-shielding films defining four adjacent pixel electrodes to an outer edge of each pixel electrode. While the first alignment control film is formed on the common electrode, a concave second alignment control film having an outer shape conforming to the convex shape is provided at a position facing the convex portion of the first alignment control film. And an alignment film is formed on each of the first and second alignment control films.