JPH05232474A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain a wider angle characteristic having poor dependency on visual angles by providing a plurality of regions varying in the orientation direction of liquid crystals within one picture element and positioning the boundary part within these regions onto such holding capacity line which divides the picture element to a plurality. CONSTITUTION:A liquid crystal material 6 is clamped between two sheets of supporting substrates 5 and the plural regions varying in the orientation directions of the liquid crystals are provided within the one picture element 1 with the holding capacity line 2 as the boundary. Although the directions of the twists are the same in the liquid crystal orientation of the divided region (I)3 and region (II)4, the orientations on the surface of the substrate vary. Further, the parts being called disclination where the orientation of the liquid crystals is discontinuous are generated at the center of the holding capacity line 2 by the structure to position the divided parts 20 of the region on the holding capacity line 2. This holding capacity line 2 is provided by using materials which do not allow the transmission of visible light, i.e., various kinds of metallic materials, such as chromium and aluminum. The inter-region parts where the disturbance in the light transmission by the disclination is generated are thereby prevented from entering the observer's eyes in actual display.

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.

[0002]

2. Description of the Related Art As a conventional liquid crystal display device which realizes a wide viewing angle by dividing an area into a plurality of areas and applying an alignment regulating force in different directions in adjacent areas, for example, Japanese Patent Application Laid-Open No. 63-63242.
There is one disclosed in Japanese Patent Laid-Open No. 106624. Here, this will be described as an example. FIG. 8 shows a plan view of this liquid crystal display element. FIG. 9 shows a sectional view of this liquid crystal display element (a sectional view taken along the line CC ′ of FIG. 7). Further, a schematic view of the rubbing direction is shown in FIG. On one glass substrate 23, a display transparent electrode 25 for each pixel, an alignment film 7, and a thin film transistor 13 for driving this transparent electrode 9-1 are formed. A transparent display electrode 24 and an alignment film 7 are formed on the other glass substrate 22. The alignment film 7 is made of polyimide. Opposing transparent electrodes 24, 25
The pixels B formed between them are, for example, squares of 200 μm in length and width, and are arranged in a matrix. A band-shaped spacer 21 made of polyimide is provided at the center of the display transparent electrode forming the pixel B. As a result, each pixel B has a region I due to the strip spacer 21.
And II. The divided regions I and II are
It is typically formed as shown in FIG. That is, the above-described area division is performed on the other glass substrate 22 facing the one glass substrate 23. This glass substrate 23,
The alignment film 22 on the liquid crystal surface is rubbed in the direction of the arrow shown in FIG.

A liquid crystal display device before this conventional example, for example,
TN with liquid crystal alignment twisted in a 90 ° spiral between the upper and lower substrates
In a (twisted nematic) type liquid crystal display element, when the viewing angle direction is tilted from the vertical direction of the substrate of the display element, the viewing angle dependence of the display appears. In this conventional example, the liquid crystal alignment in each of the divided regions has the same spiral twist direction but different angles with respect to the substrate surface. Since the rising directions of the liquid crystal molecules are different when a voltage is applied due to the difference in the angle with respect to the substrate surface, the respective regions compensate each other for optical characteristics when light is incident from an oblique direction inclined from the vertical direction with respect to the substrate. As a result, the viewing angle dependency at the time of applying a voltage is canceled by the regions having different orientations between the upper and lower substrates, and optical characteristics with little viewing angle dependency are obtained.

[0004]

However, in the above-mentioned conventional example, since the strip-shaped spacer having a thickness of 10 μm is provided by polyimide, the following problems occur.
Since it is difficult to obtain the accuracy of size in forming spacers using polyimide, the thickness of the liquid crystal display element and the area of the display region are changed, and the display uniformity cannot be obtained. Further, since the alignment of the liquid crystal is disturbed in a region of several μm on the wall surface of the spacer made of polyimide, there is a problem in that display uniformity cannot be obtained and at the same time, a sufficient optical compensation effect cannot be obtained. It was Furthermore, when the two polarizers are perpendicular to each other, the spacer part made of polyimide does not transmit light, and when the polarizers are parallel, the light is transmitted, and the transmitted light is colored by the optical characteristics of the polyimide. Resulting in. Therefore, it cannot be handled in the same manner as the light-shielding portion, causing a problem in the optical design of the element.

Further, in order to solve this problem, when a liquid crystal display element having a conventional structure is manufactured without a strip spacer, a voltage is applied to disturb the transmittance of light at the boundary of the regions. There was a problem that it occurred in a width of several μm. This is because the alignment direction of the liquid crystal on the substrate surface is different in each region. That is, when the liquid crystal molecules rise due to the voltage application, a portion called disclination in which the liquid crystal orientation is discontinuous is generated between the regions. Therefore, also in this structure, the area of this disclination disturbs the light transmittance and lowers the contrast between white and black.

An object of the present invention is to provide a liquid crystal display device having a high-angle viewing angle characteristic which does not depend on the viewing angle.

Another object of the present invention is to provide a liquid crystal display device having a wide field of view and good contrast.

[0008]

The present invention provides a liquid crystal display device in which a liquid crystal substance is sandwiched between two supporting substrates,
It is characterized in that one pixel has a plurality of regions having different liquid crystal alignment directions, and the boundary between the regions is located on a storage capacitance line that divides the pixel into a plurality of regions.

[0009]

2 is a plan view of the liquid crystal display device of the present invention, and FIG.
1 is a sectional view taken along the line AA 'in FIG. In the liquid crystal display device of the present invention, a liquid crystal substance 6 is sandwiched between two supporting substrates 5, and a plurality of regions having different alignment directions of liquid crystals are provided in one pixel 1 with the storage capacitor line 2 as a boundary. As a result, the alignment of the liquid crystal in the regions 3 and 4 in FIG. 2 becomes as schematically shown in FIG. 3 ((A) is a plan view and (B) is a cross-sectional view). Here, the area (I) 3 and the area (I
The liquid crystal alignment of I) 4 has the same twist direction, but the alignment direction on the substrate surface is different. With such an alignment direction of the liquid crystal, a liquid crystal display element having less dependence on the viewing angle can be obtained as in the conventional example.

In FIGS. 2 and 3, 7 is an alignment film and 8
Is a counter electrode, 11 is a pixel electrode, 12 is an insulating film, and 20 is an alignment division line.

Further, due to the structure in which the divided regions are located on the storage capacitor line 2, a portion called disclination in which the alignment of the liquid crystal is discontinuous occurs at the center of the storage capacitor line 2. Here, the holding capacitance is a capacitance added to improve the voltage holding characteristics in the active matrix liquid crystal display element. By providing this storage capacity line with a material that does not transmit visible light, that is, with various metal materials such as chromium and aluminum, the area between the areas where the light transmittance is disturbed due to disclination is observed by an observer. Does not see Further, since the storage capacitor line thus provided is similar to the other light-shielding portions on the display, it is not necessary to pay particular attention to the optical design.

[0012]

EXAMPLE An example of the present invention will now be described with reference to FIGS. 4 and 5 are a plan view and a sectional view showing a first embodiment of the present invention. In this example,
A thin film transistor 13 made of an active element and amorphous silicon was used. As shown in FIG. 4, the size of one unit pixel was 100 μm in length and 140 μm in width. Scan electrode line 1
0, the signal electrode line 14, and the storage capacitor line 2 were made of chromium (Cr) formed by a sputtering method and had a thickness of 10 μm. Silicon nitride (S
iNx) was used. The pixel electrode 11 is a transparent electrode IT
It was formed by sputtering using O (indium tin oxide). The storage capacitor 9 was formed of ITO by sputtering, and was formed by a photolithography process to have a size of 82 μm in length (greater than 4 μm in vertical length of pixel electrode) and 50 μm in width.
The glass substrate on which the thin film transistors were formed in an array in this manner was used as the first support substrate 16. Further, on the second support substrate 15 on the opposite side, color filters 17 are formed in an array by a dyeing method, a protective layer 18 made of silica is provided on the upper surface thereof, and a transparent electrode 8 made of ITO is further formed. did.

An alignment film 7 made of polyimide was applied on the first supporting substrate. A positive resist was applied to the surface of the alignment film, and a stripe-shaped mask was used to divide a region between the center lines of the storage capacitor lines 2 of the adjacent pixels into a masked region and an exposed region. After developing the resist in the exposed area,
Rubbed. Furthermore, the resist is applied again, the masked area is reversed from the previous one, and the resist on the surface of the alignment film in the unrubbed area is removed by exposing and developing, and the surface is 180 ° from the previous rubbing direction.
Rubbing is applied in different directions. The second support substrate was also subjected to the alignment treatment in the same manner as the first support substrate, but the rubbing direction was twisted by 90 °. The two substrates were bonded together with an adhesive via a spacer made of silica particles, and nematic liquid crystal 19 was injected as shown in FIG.

In this embodiment, as shown in FIG. 5, the orientation was bisected within one pixel with the storage capacitor line as a boundary. 6 and 11 show the measurement results of the viewing angle dependence of the transmittance in the 225 ° azimuth direction of the liquid crystal display element according to the present invention and the conventional TN type liquid crystal display element during gradation display. As is clear from comparison of these measurement results, a wide-angle viewing angle characteristic having no viewing angle dependency can be obtained even in gradation display.

Further, FIG. 7 shows, as a second embodiment, an example in which the present invention is applied to a liquid crystal display element which functions as a storage capacitor by a scanning electrode line. In the embodiment of FIG. 7, the size of one unit pixel is 100 μm in the vertical direction, as in the first embodiment.
The width was 140 μm. The scanning electrode lines 10 and the signal electrode lines 14 were made of chromium formed by a sputtering method and had a thickness of 10 μm. Further, the pixel electrode 11 is formed of ITO (indium tin oxide) by a sputtering method, and is formed in a height of 66 μm and a width of 130 μm by a photolithography process. The scanning electrode line 10 was provided so as to be located at the center of the pixel. The glass substrate with the thin film transistor array thus configured was used as the first supporting substrate. The second supporting substrate was manufactured by the same process as in the first embodiment. The boundary between the regions for dividing the alignment was positioned at the center of the scanning electrode, and the rubbing process, the exposing process, and the rubbing process were performed in the same manner as in the first embodiment to obtain a substrate having regions having different alignment regulating forces. The substrate was bonded with an adhesive via a spacer, and nematic liquid crystal was injected. Since it is not necessary to separately provide the storage capacitor line, the structure is simplified and the manufacturing yield is increased. In addition, a region where the light transmittance is not uniform due to disclination generated between the regions when a voltage is applied is formed on the scanning electrode line 1.
Since it was covered with 0, the region where the light transmittance was disturbed did not enter the eyes of the observer, and a wide-field liquid crystal display device having good contrast was obtained.

[0016]

According to the present invention, even if the alignment direction of the liquid crystal is changed depending on the strength of the voltage application, optical compensation is performed within the pixel. Also, it is possible to obtain a liquid crystal display element having a wide viewing angle characteristic that does not depend on the viewing angle. Further, the region where the light transmittance is disturbed due to the disclination that occurs between the regions is shielded by the storage capacitance line and therefore does not enter the eyes of the observer.
As a result, a liquid crystal display device having a wide field of view and good contrast can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view of a liquid crystal display element of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG.

FIG. 3 is a plan view and a sectional view schematically showing an example of the liquid crystal display element of the present invention.

FIG. 4 is a plan view showing a first embodiment of a liquid crystal display element according to the present invention.

5 is a cross-sectional view taken along the line BB ′ of FIG.

FIG. 6 is a diagram showing a measurement result of viewing angle dependence of transmittance in an azimuth angle of 225 ° when displaying a gradation of a liquid crystal display device according to the present invention.

FIG. 7 is a plan view showing a second embodiment of the liquid crystal display element according to the present invention.

FIG. 8 is a plan view of a conventional liquid crystal display device in which a region is divided for the purpose of wide field of view.

9 is a cross-sectional view taken along the line CC ′ of FIG.

FIG. 10 is a schematic view of a rubbing direction of a liquid crystal display element in which a conventional area is divided.

FIG. 11 is an azimuth angle 22 of a liquid crystal display element that does not divide a region.
It is a figure showing the viewing angle dependence of the transmittance | permeability in a 5 degree direction.

[Explanation of symbols]

 1 Pixel 2 Storage Capacitance Line 3, 4 Divided Area 5 Supporting Substrate 6 Liquid Crystal Material 7 Alignment Film 9 Storage Capacitance 10 Scanning Electrode 13 Thin Film Transistor 14 Signal Electrode Line

Claims (1)

[Claims] 1. In a liquid crystal display device in which a liquid crystal substance is sandwiched between two supporting substrates, one pixel has a plurality of regions having different liquid crystal alignment directions, and the boundary portion between the regions is a pixel. An active matrix type liquid crystal display element characterized by being positioned on a storage capacitor line which is divided into a plurality of parts.