JPH0943610A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good-contrast display picture by improving an opening ratio of a picture element electrode in a liquid crystal display device using TFT. SOLUTION: Instead of a conventional stored capacity line, a scanning line 24 is provided on a boundary of a first area 21a and a second area 21b of which picture element electrodes 21 are oriented in a different direction from each other and both areas 21a, 21b are supplied with a scanning signal, and also disclination line is coated. On the other hand, a stored capacity line 25 is provided at the upper and lower parts of the picture element electrodes 21. Thus, an opening ratio of the picture element electrodes 21 can be improved by resolving a tilt reverse which is generated by a potential difference from conventional picture element electrode parts and unnecessitating its shielding.

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 in which a liquid crystal layer is held between substrates, and more particularly to a liquid crystal display device in which each display pixel is display-controlled by a thin film transistor (hereinafter abbreviated as TFT). .

[0002]

2. Description of the Related Art Recently, in order to obtain high functionality and high definition, TF
In an active matrix type liquid crystal display device that performs display control of display pixels arranged in a matrix using T, one pixel has a different molecular arrangement as a method of improving the viewing angle characteristic which is a problem peculiar to the liquid crystal display device. A method of dividing into two regions has been proposed.

In this active matrix type liquid crystal display device, scanning lines and signal lines are provided on a transparent insulating substrate so as to be orthogonal to each other, and a switching element and a pixel electrode are connected at each intersection. A TFT, which is a semiconductor switch, is usually used for a switching element used as a means for driving and controlling each pixel, because a transmissive display is possible and a large area is easy.

A TFT is a type of insulated gate field effect transistor, in which the gate is connected to the scanning line, the drain is connected to the signal line, and the source is connected to the pixel electrode. In addition to this, the array substrate may be provided with a storage capacitor in order to sufficiently increase the time constant of discharging the capacitance of the liquid crystal serving as the load of the TFT of each pixel. One end of the storage capacitor is the pixel electrode,
The other end is usually connected to the storage capacitance line. An alignment division type liquid crystal display device using this array substrate shields a disclination line appearing at a boundary between regions having different molecular orientations with a storage capacitor line.

[0005]

In an alignment division type liquid crystal display device, a disclination line is generated at a boundary between regions having different alignment directions of the pixel electrodes. Therefore, it is necessary to shield the disclination line. Although it also causes a reduction in the aperture ratio of the pixel electrode, conventionally, the storage capacitor line is provided at the boundary of the region of the pixel electrode and also serves as the shielding means.

Further, in the peripheral portion of the pixel electrode, a tilt reverse occurs due to the relationship between the horizontal electric field generated by the potential difference between the signal line and the scanning line and the direction of the pretilt, and this tilt reverse is converted into a black matrix. Therefore, there is a problem that the aperture ratio is lowered because it is necessary to shield it.

Therefore, the present invention eliminates the above-described problem, prevents the tilt reverse which has conventionally occurred at the end of the pixel electrode due to the potential difference from the scanning line, and improves the aperture ratio of the display area. An object of the present invention is to provide a liquid crystal display device capable of obtaining a clear display image having a high contrast ratio in consideration of the shielding of disclination lines generated in the pixel electrode.

[0008]

In a liquid crystal display device according to a first aspect of the present invention, the pixels arranged in a two-dimensional matrix form a pair of a first pixel electrode and a second pixel electrode, 1 of which the pixel electrode and the second pixel electrode are connected
One or two thin film transistors, a signal line connected to the thin film transistor, and a signal line that is orthogonal to the signal line and that passes through the boundary between the first pixel electrode and the second pixel electrode and is connected to the thin film transistor. A scanning line for supplying a scanning signal is provided, and the alignment direction on the first pixel electrode is different from that on the second pixel electrode.

In another embodiment, the storage capacitance line is
It is characterized in that it is installed at the boundary between adjacent pixel electrodes.

[0010]

As described above, according to the liquid crystal display device of the present invention, a single scanning line is provided at the boundary between the first and second pixels,
By supplying the scanning signal to both pixels, the tilt reverse at the pixel end, which occurs when the conventional scanning line is provided at the pixel electrode end, becomes small, and it is not necessary to shield it with the black matrix. However, it is possible to reduce the shielding means at the pixel end portion, improve the aperture ratio of the pixel electrode, and obtain a good-quality image display with a good contrast ratio. On the other hand, when the orientation division method is used, the disclination line generated at the boundary between two regions having different molecular arrangement directions can be shielded by the scanning line instead of the storage capacitance line. Further, the storage capacitance line is not provided in the display area of the pixel electrode, but is installed at the boundary with the adjacent pixel, and the upper and lower sides of the opening are regulated to improve the aperture ratio and reduce the contrast due to disclination. To prevent.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the first embodiment shown in FIGS. Reference numeral 10 denotes a liquid crystal display device using a TFT, which is Indium-Tin-Oxide.
(Hereinafter abbreviated as ITO) TFT array substrate 20 having matrix-shaped pixel electrodes 21 and ITO
The liquid crystal composition 13 is held between the opposing substrates 30 having the transparent electrodes 31 made of (4) through the alignment films 11 and 12. Reference numeral 14 is a spacer for controlling both substrates 20 and 30 at a predetermined interval.

Next, the signal line 2 is formed on the TFT array substrate 20.
3 and the scanning lines 24 are arranged in a matrix, and TFTs 22 using amorphous silicon are arranged at the respective intersections and connected through contact holes (not shown). Further, a pixel electrode 21 connected to the TFT 22 is formed so as to sandwich the scanning line 24. This pixel electrode 2
One pixel includes a first region 21a having an alignment direction of an arrow s direction and a second region 21 having an alignment direction of an arrow t direction different from the first region 21a by 180 °.
It consists of b pairs.

The TFT array substrate 2 constructed as described above
0 and the alignment films 11 and 12 made of polyimide are formed on the surface of the counter substrate 30, respectively, and then the first rubbing process is performed.

Next, by means of photolithography, the alignment film 11 and the transparent electrode 31 on the side of the position where the scanning line 24 of the TFT array substrate 20 is arranged, which corresponds to a half region of the pixel electrode 21, are described above. The alignment film 12 at a position corresponding to the region opposite to the region is covered with a resist, and a second rubbing treatment different in 180 ° direction from the first rubbing direction is performed.

After the resist is removed, epoxy adhesive 16 is printed along the periphery of the alignment film 12 of the counter substrate 30 except for the injection port, and the surface of the counter substrate 30 has a grain size of 6 μm.
m spacers 14 are sprinkled.

Next, the TFT array substrate 20 and the counter substrate 3
0 is opposed to each other so that the rubbing directions of the alignment films 11 and 12 form 90 °, and then heated to cure the adhesive 16.
Both substrates 20 and 30 are bonded together to form a liquid crystal cell.

After that, E.
After injecting the liquid crystal composition 13 in which 0.18% by weight of S811 is added to ZLI-1565 manufactured by Merck, the injection port is sealed with an ultraviolet curable resin.

Further, the TFT array substrate 20 and the counter substrate 3
Polarizing plates 17 and 18 are attached to the outside of the liquid crystal display device to manufacture a liquid crystal display device.

According to this structure, the first and second regions 21a and 21b of the pixel electrode 21 are provided on both sides of the scanning line 24, and a scanning signal is supplied to both regions 21a and 21b. The tilt reverse generated at the end of the pixel electrode due to the potential difference between and is eliminated, and it is not necessary to shield the tilt reverse part at the end of the pixel electrode. The liquid crystal display device 10 can be enlarged, and thus the aperture ratio of the liquid crystal display device 10 can be enlarged, and an active matrix liquid crystal display device of an alignment division system having a good contrast ratio can be obtained.

The aperture ratio of the liquid crystal display device 10 manufactured in the above embodiment is the same as that of the conventional device in which the scanning line is provided at the end of the pixel electrode and the storage capacitance line is provided at the boundary between the two regions of the pixel electrode. It was improved to about 60% compared to about 45%.
Further, the contrast ratio was remarkably improved to 200 as compared with 90 in the conventional device, and a good display image was obtained.

Next, a second embodiment will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the second embodiment, on the array substrate 20 similar to the first embodiment, the first region 21a and the second region 21a and the second region 21a, which are connected to the TFT 22 so as to sandwich the scanning line 24 like the first embodiment, are provided. The pixel electrode 21 formed of a pair of 21b is formed, and the storage capacitance line is arranged between the adjacent pixel electrodes 21. Then, similarly to the first embodiment, application of an alignment film, rubbing treatment, assembling of a liquid crystal cell, and injection of a liquid crystal composition are carried out to prepare a liquid crystal display device.

According to this structure, as in the first embodiment, the first pixel electrodes 21 provided on both sides of the scanning line 24 are provided.
By supplying the scanning signal to the second regions 21a and 21b, the tilt reverse generated at the end portion of the pixel electrode due to the potential difference from the conventional scanning line is eliminated, and the tilt reverse portion is removed at the end portion of the pixel electrode. Since there is no need to shield, the opening at the edge of the pixel electrode can be enlarged compared to the conventional one, and the reduction in contrast due to disclination can be prevented. As a result, the aperture ratio is high and the contrast is high. A matrix liquid crystal display device can be obtained.

The aperture ratio of the liquid crystal display device manufactured in the second embodiment is the same as that of the conventional liquid crystal display device in which the scanning line is provided at the end of the pixel electrode and the storage capacitance line is provided at the boundary between the two regions of the pixel electrode. The equipment was improved to approximately 50%, compared to approximately 45%. Further, the contrast ratio was remarkably improved to 150 compared with 90 in the conventional apparatus, and a good display image was obtained.

The present invention is not limited to the above-mentioned embodiments, and modifications can be made without departing from the spirit of the invention.
For example, the material of the TFT, the number of pixel electrodes, and the like are arbitrary. Furthermore, the angle and the like of the first and second regions in the pixel electrode are not limited as long as the orientation directions are different.

[0025]

As described above, according to the present invention, T
In the active matrix liquid crystal display device of the alignment division type using FT, the tilt reverse generated at the end portion of the pixel electrode can be reduced, so that the shielding means is unnecessary, the aperture ratio of the pixel electrode can be improved, and the contrast ratio can be improved. It is possible to obtain a high quality display image.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a liquid crystal display device of a first embodiment of the present invention.

FIG. 2 is a TFT of the liquid crystal display device according to the first embodiment of the present invention.
It is a schematic plan view which shows an array substrate.

FIG. 3 is a TFT of a liquid crystal display device according to a second embodiment of the present invention.
It is a schematic plan view which shows an array substrate.

[Explanation of symbols]

 10 ... Liquid crystal display device 21 ... Pixel electrode 21a ... 1st area | region 21b ... 2nd area | region 24 ... Scan line 25 ... Storage capacity line

Claims (2)

[Claims] 1. Pixels arranged in a two-dimensional matrix form a pair of a first pixel electrode and a second pixel electrode, and the first pixel electrode and the second pixel electrode are connected to each other.
One or two thin film transistors, a signal line connected to the thin film transistor, and a signal line that is orthogonal to the signal line and that passes through the boundary between the first pixel electrode and the second pixel electrode and is connected to the thin film transistor. A liquid crystal display device, comprising: a scanning line for supplying a scanning signal, wherein the alignment directions on the first pixel electrode and the second pixel electrode are different. 2. The liquid crystal display device according to claim 1, wherein
A liquid crystal display device, wherein a storage capacitor line is installed at a boundary between adjacent pixel electrodes.