JPH06110082A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal device which is improved in contrast by preventing a disclination line from being formed intruding a pixel electrode greatly and improving the aperture rate of the pixel electrode. CONSTITUTION:Scanning signal lines 1 and image signal lines 2 are provided in matrix on a substrate and pixel electrodes 3 are provided at the intersections of the scanning signal lines 1 and image signal lines 2; and a transistor 4 for switching has its gate electrode 4a connected to a scanning signal line 1 and its source and drain electrodes 4b and 4c connected to an image signal line 2 and the pixel electrode 3. Further, a projection part 3a and the switching transistor 4 are provided at the disclination line generation part of the pixel electrode 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device, and more particularly to a liquid crystal device used for a display device such as a personal computer, a word processor, a small television and a light control device such as a liquid crystal shutter.

[0002]

2. Description of the Related Art A conventional liquid crystal device is shown in FIGS. 3 is a sectional view of the pixel electrode portion, and FIG. 4 is a plan view. In this conventional liquid crystal device, scanning signal lines 12 and image signal lines 13 are provided in a matrix on a transparent substrate 11 such as glass, and pixel electrodes 14 are provided at respective intersections of the scanning signal lines 12 and image signal lines 13. The gate electrode 15a is connected to the scanning signal line 12, and the source / drain electrodes 15b are connected to the image signal line 13 and the pixel electrode 14, respectively.
One pixel is configured by providing the switching transistor 15 to which 15c is connected. A second transparent substrate 16 such as glass is provided in a portion facing the substrate 11, and a counter electrode 17 is formed on the second transparent substrate 16. Further, on the substrate 11 and the substrate 16, an alignment film 18 rubbed in a certain direction,
19 is formed. The liquid crystal 20 is sandwiched between the first substrate 11 and the second substrate 16. Although not shown, a polarizing plate is provided outside the substrates 11 and 16.

In such a liquid crystal device, when no voltage is applied to the pixel electrode 14, the liquid crystal 20 has the alignment films 18 and 1.
Light radiated from one side of the substrate 11 or the substrate 16 is dominated by the rubbing direction of 9 and twisted and arranged at a certain angle, and is transmitted through the liquid crystal 20 to be extracted from the other side of the substrate.

Further, when an image signal voltage is applied to the pixel electrode 14 through the switching transistor 15, the liquid crystal molecules 20 in the pixel electrode 14 portion are covered by the first substrate 1.
Lights radiated from one side of the substrate 11 or the substrate 16 are arranged almost vertically to the first and second substrates 16 and are blocked by the polarizing plate and do not pass through.

[0005]

However, in this conventional liquid crystal, the area of the pixel electrode 14 is very small with respect to the counter electrode 17, and the pixel electrode 14 and the scanning signal line 12 are provided. Therefore, a lateral electric field is generated in the vicinity of the pixel electrode 14 and the scanning signal line 12 due to the influence of the potentials of the pixel electrode 14 and the scanning signal line 12. This transverse electric field
In a region different from the molecular axis direction Y of the liquid crystal molecules 20, the liquid crystal molecules 20 act so as to stand upright, and disclination occurs in which the orientation of the liquid crystal molecules 20 is disturbed. Since the light transmission intensity is different between the region where the disclination occurs and the other region, the disclination line Z appears near the boundary. The disclination line Z is generated so as to largely penetrate from one corner of one side of the pixel electrode 14 to the other corner. Pixel electrode 1
When such a disclination line Z appears in 4, the light leaks, for example, even when black display is performed. Therefore, the contrast, which is the ratio of the transmitted light amount in black display and the transmitted light amount in white display, becomes As well as the deterioration, the display quality is significantly impaired.

In order to eliminate such an influence of the disclination line Z, conventionally, a light-shielding film 21 made of black paint or the like is applied to the peripheral portion of the pixel electrode 14 where the disclination line Z appears, to form a disc. Although the lineation line Z was concealed, when the light shielding film 21 is applied to the peripheral edge of the pixel electrode 14, the aperture ratio of the pixel electrode 14 becomes small, resulting in a dark display panel as a whole. There was a problem that the contrast was lowered.

[0007]

The liquid crystal device according to the present invention has been made in view of the above problems of the prior art. The feature of the invention described in claim 1 resides in that Scan signal lines and image signal lines are provided in a matrix, pixel electrodes are provided at respective intersections of the scan signal lines and image signal lines, and gate electrodes are connected to the scan signal lines, and the image signal lines and the pixels are connected to each other. In a liquid crystal device provided with a switching transistor in which a source / drain electrode is connected to an electrode, a convex portion is provided at a disclination line generating portion of the pixel electrode. Also,
The feature of the invention described in claim 2 is that a switching transistor is provided in the disclination line generating portion of the pixel electrode.

[0008]

As described above, when the disclination line generating portion of the pixel electrode is provided with the convex portion or the switching transistor, the influence of the horizontal electric field of the scanning signal line is reduced, and the disc electrode is formed on the pixel electrode. It is possible to prevent the occurrence of a large penetration of the line, and thus to improve the aperture ratio of the pixel electrode portion to improve the contrast.

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram of a pixel electrode portion showing an embodiment of a liquid crystal device according to the invention described in claim 1.
Is a scanning signal line, 2 is an image signal line, 3 is a pixel electrode, and 4 is a switching transistor.

A plurality of the scanning signal lines 1 and the image signal lines 2 are provided, and a plurality of the scanning signal lines 1 and the image signal lines 2 are provided.
Are provided in a matrix so as to intersect each other.

The scanning signal line 1 and the image signal line 2 are each formed of a metal thin film such as aluminum (Al), tantalum (Ta), or chromium (Cr), and silicon nitride (SiN _x ) or silicon nitride (SiN _x ) is formed at the intersection. Tantalum oxide (Ta
O _X) electrical insulating film such as a (not shown) is interposed.

A pixel electrode 3 is provided at each intersection of the scanning signal line 1 and the image signal line 2. The pixel electrode 3 is formed of a transparent conductive film such as tin oxide or indium tin oxide.

A switching transistor 4 is provided at a corner portion of the pixel electrode 3, and a gate electrode 4a of the switching transistor 4 has a scanning signal line 1a.
Source / drain electrodes 4b, 4c
Are connected to the image signal line 2 and the pixel electrode 3. That is, the switching transistor 4 is turned on / off by the scanning signal supplied via the scanning signal line 1, and supplies the image signal voltage supplied via the image signal line 2 to the pixel electrode 3.

The pixel electrode 3 and the counter electrode (not shown)
An alignment film for regulating the alignment direction of the liquid crystal material is provided on the top. The alignment film on the pixel electrode 3 is rubbed in the A direction in FIG. 1, for example, and the alignment film on the counter electrode is rubbed in the B direction in FIG. When the alignment film is rubbed in such a direction, the disclination line largely penetrates into the lower left corner of the pixel electrode 3 and is generated. However, in the present invention, a convex portion is formed at the lower left corner of the pixel electrode 3. 3a is provided,
By generating the disclination line Z in the convex portion 3a, the disclination line Z
The invasion distance into the pixel electrode 3 becomes shorter. That is, since the scanning signal line 1 and the pixel electrode 3 are closest to each other in the convex portion 3a, the influence of the lateral electric field is strongest in the convex portion 3a, and the disclination is applied to the convex portion 3a.・ Line Z will be generated. Although not shown, this convex portion 3a may be covered with a light shielding film made of black resin or the like. The position of the disclination line Z generated by being dominated by the rubbing direction of the alignment film on the pixel electrode 3 and the alignment film on the counter electrode is different. For example, when rubbing in the directions A and B opposite to each other in FIG. 1, the disclination line Z
Is generated by greatly penetrating into the upper right corner of the pixel electrode 3. Therefore, it is important to provide the convex portion 3a at a portion where the disclination line Z is generated based on the rubbing direction of the alignment film.

FIG. 2 is a diagram showing an embodiment of a liquid crystal device according to the invention described in claim 2. The scanning signal line 1, the image signal line 2, and the pixel electrode 3 are the same as those in the liquid crystal device shown in FIG. In addition, in the liquid crystal device shown in FIG.
The upper alignment film is rubbed in the A direction in FIG. 2, and the alignment film on the counter electrode (not shown) is rubbed in the B direction in FIG. Therefore, the disclination line Z
Occurs so as to enter the lower left corner of the pixel electrode 3.

Therefore, in the invention described in claim 2, the switching transistor 4 is provided at the lower left corner of the pixel electrode 3 so that the disclination line becomes the pixel electrode 3
To prevent intrusion into. That is, it is possible to prevent a disclination line from being generated on the pixel electrode 3 due to the influence of the electric field generated on the drain electrode 4c of the switching transistor 4. Also in the liquid crystal device of FIG. 2, when the rubbing direction of the alignment film is changed, the generation position of the disclination line is different, but it is essential to provide the switching transistor 4 in accordance with this generation position.

[0017]

As described above, in the liquid crystal device according to the present invention, the disclination line generating portion of the pixel electrode is provided with the convex portion or the switching transistor. It is possible to prevent the nation line from penetrating into the liquid crystal display device, and the aperture ratio of the pixel electrode is improved, resulting in a liquid crystal device having improved contrast.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a liquid crystal device according to the invention described in claim 1.

FIG. 2 is a diagram showing an embodiment of a liquid crystal device according to the invention described in claim 2.

FIG. 3 is a cross-sectional view of a pixel electrode portion showing a conventional liquid crystal device.

FIG. 4 is a plan view of a pixel electrode portion showing a conventional liquid crystal device.

[Explanation of symbols]

1 ... Scan signal line, 2 ... Image signal line, 3 ... Pixel electrode, 3a ... Convex part, 4 ... Switching transistor.

Claims (2)

[Claims] 1. A scanning signal line and an image signal line are provided in a matrix on a substrate, a pixel electrode is provided at each intersection of the scanning signal line and the image signal line, and a gate electrode is connected to the scanning signal line, Further, in the liquid crystal device in which the switching transistor in which the source / drain electrodes are connected to the image signal line and the pixel electrode is provided, the disclination line generating portion of the pixel electrode is provided with a convex portion. Liquid crystal device. 2. A scanning signal line and an image signal line are provided in a matrix on a substrate, a pixel electrode is provided at each intersection of the scanning signal line and the image signal line, and a gate electrode is connected to the scanning signal line, Further, in the liquid crystal device in which the switching transistor in which the source / drain electrodes are connected to the image signal line and the pixel electrode is provided, the switching transistor is provided in the disclination line generating portion of the pixel electrode. And liquid crystal device.