JPH1020313A - Active matrix type liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody a desired orientation state in the respective regions within respective pixels of an orientation division type panel and to improve its visual field angle characteristic. SOLUTION: This liquid crystal display element is formed by sealing liquid crystals between an active matrix substrate 1B having active elements 3 in the plural pixels 2 and a substrate 1A having common electrodes facing the same. In such a case, at least one substrate 1B has the plural regions varying in the orientation bearing or pretilt angle of the liquid crystal molecules. These regions are so formed that their boundaries do not overlap on the signal lines 14 of either row direction or column direction of the active matrix substrate 1B. The boundaries of the plural regions described above can exist within the pixels 2 in which the ruggedness of the stabler orientation state does not exits. The orientation of the respective regions are, therefore, stabilized and the divided orientations uniform over the entire part of the screen of the wide visual field angle panel having the plural orientation states in the pixels 2 are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices are thin, lightweight, and low power consumption display devices, and are widely used in image display devices such as televisions and videos and OA equipment such as word processors and personal computers. Among the liquid crystal display elements, most of the active matrix type liquid crystal display elements in which a number of switching elements are arranged on an array substrate use a twisted nematic (TN) mode in which the orientation direction of the liquid crystal is twisted almost 90. It is being developed as a display capable of high-speed response and high definition.

[0003] However, the TN mode liquid crystal display element has a major drawback that the color tone and contrast differ depending on the angle at which the panel is viewed, since the display is performed using the optical rotation of the liquid crystal. For this reason, the viewing angle range in which a good display can be obtained is considerably narrower than that of a cathode ray tube (CRT).
Display performance equal to or higher than RT has not yet been realized.

In general, in an active matrix type liquid crystal display device, a normally white mode (hereinafter, NW mode) in which white display is performed in a state where no voltage is applied, and a normally black mode (hereinafter, referred to as NW mode) in which black display is performed without application of a voltage. NB mode). The NB mode has a relatively wide viewing angle range defined by contrast and gradation display performance, but has a strong wavelength dependence in display characteristics and has difficulty in uniform hue display.
In addition, since the color tone is greatly different due to a slight difference in the panel gap, there are many problems in the construction method.

On the other hand, in the NW mode, a polarizing plate is arranged orthogonally on both sides of a panel, and a black display is performed by applying a voltage, so that the contrast can be easily increased. Further, even if the panel gap is slightly different, the hue does not largely change, so that the method is excellent in terms of construction method. However, the viewing angle range is N
It is much narrower than B mode. Among these display modes, in recent years, NW has been considered from the viewpoint of panel contrast and color tone.
Mode display is widely used, but has an essential problem of a narrow viewing angle range.

As a technique for widening the viewing angle of such a NW mode TN type liquid crystal display element, an electrode division method and an alignment division method having a plurality of different alignment regions in a pixel are known. Electrode splitting method (for example, A. Lien et.al., Society of
Information Display 93 digest P.269) is to create a plurality of areas in a pixel by disposing a rectangular hole in a part of the counter electrode of the pixel and distorting the electric field distribution in the panel. By averaging the angular azimuth, a wide viewing angle can be realized.

The electrode division method includes a method in which the liquid crystal layer forms a homeotropic arrangement and a method in which the liquid crystal layer forms a twisted nematic (TN) arrangement. The former has the advantage that rubbing is not required, but the TN alignment is used because the development of the n-type liquid crystal to be used is insufficient and there is a problem in the reliability of the alignment agent. R & D is more active.

On the other hand, in the orientation division method, a plurality of regions with different pre-tilt angles or orientations are provided in a pixel to produce a plurality of regions in different orientations, and a wide viewing angle is realized by averaging the viewing angles of the liquid crystal. Is what you do. In order to obtain a plurality of alignment regions in a pixel, there are methods such as mask exposure by ultraviolet light, mask rubbing by photolithography, and electric field assist.

In recent years, the fineness of the panel has been improved even in a small panel, and accordingly, the pixel size has been reduced. When one pixel is divided into a plurality of alignment regions by the pixel division method, the area of one region is very small. On the other hand, the viewing angle characteristics when a plurality of alignment regions are provided in a pixel by the alignment division method are symmetric in the upper and lower directions and the left and right directions when the pixel is vertically divided into two, but the vertical direction is different. It is narrower than the left-right direction and is not symmetric in all directions. In order to further increase the symmetry (reduce the viewing angle dependency), it is preferable to divide each pixel into more regions having different orientations.

Conventionally, when dividing an alignment region in a pixel, for example, as described in Japanese Patent Application Laid-Open No. Hei 5-173135, a pixel is used as a repetition unit based on a signal line in both a row direction and a column direction. The method was common.

[0011]

When a pixel is divided on the basis of a signal line, the boundaries of regions having different orientations or pretilt angles inevitably overlap on the signal line. However, in the case of an active matrix type liquid crystal display element, a step is large on a signal line, particularly on a TFT, and it is difficult to perform a uniform rubbing treatment, and the alignment state tends to be unstable. If there is a boundary between regions having different orientations in this portion, there is a problem that each region is difficult to exist stably.

Further, when the number of divisions in one pixel is increased in order to further reduce the viewing angle dependence, the area of one region is reduced. When regions with different twist directions are mixed, each region tends to expand to stabilize the alignment state, so that the region with a low pretilt angle, the region with a small alignment regulating force, the region with a high pretilt angle, or It is easily eroded in a region having a large alignment regulating force. Therefore, when the pixel size is small, there is a problem that it is difficult to obtain a desired divided orientation.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an active matrix type liquid crystal display device which realizes a desired alignment state in each region in each pixel and has good viewing angle characteristics in view of the conventional problems. To provide.

[0014]

According to a first aspect of the present invention, there is provided an active matrix type liquid crystal display device in which liquid crystal is sealed between an active matrix substrate having an active element in a plurality of pixels and a substrate having an opposing common electrode. A matrix type liquid crystal display element, in which at least one of the substrates has a plurality of regions having different alignment directions or pretilt angles of liquid crystal molecules, and a boundary between these regions is either a row direction or a column direction of the active matrix substrate. It does not overlap with a signal line.

The vicinity of the signal line is a portion where a large difference in level and uniform rubbing treatment is difficult to be performed, and the alignment state is likely to be unstable. However, as described above, the boundary between a plurality of regions having different alignment directions or pretilt angles of liquid crystal molecules. Does not overlap with the signal lines of the active matrix substrate, so that the boundary can exist in a more stable pixel without unevenness in the alignment state. For this reason, the orientation of each region is also stabilized, and a uniform divided orientation over the entire screen can be obtained in a wide viewing angle panel having a plurality of orientation state regions in a pixel. Further, it is possible to obtain a stable and high-quality image display without causing uneven brightness unevenness in the screen.

An active matrix type liquid crystal display element according to a second aspect is an active matrix type liquid crystal display element in which liquid crystal is sealed between an active matrix substrate having active elements in a plurality of pixels and a substrate having a common electrode facing the active matrix substrate. Each of the two substrates has a plurality of regions having different alignment directions or pretilt angles of liquid crystal molecules, and the intersections of the signal lines in the row direction and the column direction of the active matrix substrate are aligned with a plurality of different alignments formed by the two substrates. It is characterized by being included in one of the orientation regions.

The intersection of the signal lines is a TF having a larger step.
Since there is also T, the alignment state is more likely to be non-uniform than in the vicinity of the signal line. However, as described above, the intersection of the signal line in the row direction and the column direction of the active matrix substrate is set to one of a plurality of different alignment regions. Since it is included in the region, the boundary between the different alignment regions is in the pixel without unevenness. For this reason,
Since the alignment state in the vicinity of the boundary is stable, each alignment region can also exist stably. As in the case of claim 1, uniform divided alignment is obtained over the entire screen, and uneven brightness unevenness occurs in the screen. No stable, high-quality video display can be obtained.

According to a third aspect of the present invention, there is provided an active matrix type liquid crystal display element according to the second aspect, wherein the regions of one substrate having different orientation directions or pretilt angles of the liquid crystal molecules include the signal lines in the row direction, and the other substrate has the same structure. The region includes a signal line in a column direction, and four alignment regions having different twist directions are arranged in a checkered pattern. As described above, regions of one substrate having different orientation directions or pretilt angles of liquid crystal molecules include signal lines in the row direction, and regions of the other substrate include signal lines in the column direction, and four regions having different twist directions. Since the two alignment regions are arranged in a checkered pattern, the boundaries of the alignment regions extend almost straight up, down, left, and right, and the alignment state is as designed in almost all pixels, and a uniform alignment division pattern is obtained over the entire screen. Can be In addition, since the intersection of the signal lines is included in each alignment region, the region size can be increased,
The orientation of the liquid crystal molecules becomes more stable.

An active matrix type liquid crystal display element according to a fourth aspect of the present invention is an active matrix type liquid crystal display element in which liquid crystal is sealed between an active matrix substrate having active elements in a plurality of pixels and a substrate having a common electrode facing the active matrix substrate. The two substrates have a plurality of stripe-shaped regions each having a different orientation direction or pretilt angle of liquid crystal molecules, and an intersection of signal lines in a row direction and a column direction of an active matrix substrate is formed by the two substrates. In one of the different alignment regions, and the alignment region has a stripe shape substantially parallel to the signal line in either the row direction or the column direction.

As described above, the intersection of the signal lines in the row direction and the column direction of the active matrix substrate is included in one of a plurality of different alignment regions.
Similarly, the boundaries between different alignment regions are present in pixels without unevenness. For this reason, since the alignment state near the boundary becomes stable,
Each alignment region can also exist stably. In addition, since the alignment region has a stripe shape substantially parallel to the signal line in either the row direction or the column direction, the upper and lower pixels sandwiching the signal line have regions of the same alignment state, and the alignment state becomes unstable. A large area can be formed in the easy part. For this reason, the area of one region can be made larger than that of a liquid crystal display element of a type in which the boundary between the two substrates intersects, so that each region can exist very stably.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An active matrix type liquid crystal display device according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1 and FIG. 2 which is a cross section taken along line FF of FIG. 1, this active matrix type liquid crystal display element has an active matrix array substrate 1B having a plurality of pixels 2 having a thin film transistor (TFT) element 3 as an active element. The liquid crystal is sealed between the glass substrate 1A having the common electrode 11 opposed thereto. A plurality of regions having different pretilt angles are formed on the active matrix array substrate 1B, and the boundaries of these regions are configured not to overlap the signal lines 14 in the row direction of the active matrix array substrate 1B.

Next, the manufacturing process of this active matrix type liquid crystal display device will be described. First, the glass substrate 1 on which the transparent electrode 11 shown in FIGS.
A was offset-printed on A with an alignment film 12A exhibiting a medium pretilt angle (for example, Optmer AL5417 manufactured by Nippon Synthetic Rubber Co., Ltd.). On the other hand, the pixels 2 are arranged in a matrix as shown in FIGS. 2 and 4, and a thin film transistor (TFT) element 3 is formed in each pixel 2 on an active matrix array substrate 1B.
B (for example, Optmer AL3046 manufactured by Nippon Synthetic Rubber Co., Ltd.)
Was offset printed. By this printing method, the alignment film 1
2A and 12B were uniformly formed on the entire screen. These substrates 1A and 1B are heated at 190 ° C. for one hour,
A and 12B were cured. Thereafter, rubbing treatment was performed on both substrates 1A and 1B with rayon cloth in rubbing directions 9 and 10 indicated by arrows shown in FIGS.

Next, a positive photoresist (for example, OFPR-5000 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to the substrate 1B on which the high pretilt alignment film 12B is formed by spin coating, and heated on a hot plate at 90 ° C. for 10 minutes. To cure. At this time, the thickness of the photoresist was 1 μm. Next, the substrate 1B was irradiated with ultraviolet rays using a striped photomask in which light shielding portions were formed at the same pitch 5 as the pixel pitch in the row direction. At this time, the arrangement method of the photomask is such that the upper and lower halves of each pixel are shielded from light by the light-shielding portion sandwiching the signal lines 14 in the row direction every other row.

The substrate 1B is washed with an alkali developing solution (for example,
Immerse in NMD-3) manufactured by Tokyo Ohka Kogyo for 1 minute and rock,
The photoresist in the exposed part 16 was dissolved. as a result,
A resist pattern as shown by the hatched portion in FIG. 5 was formed. Then, it is immersed in acetone and rocked, and the non-exposed portion 17
Of the photoresist 8 was also removed. The substrate 1B and the substrate 1A that has not been subjected to photolithography are opposed so that the electrodes 11 face each other and the rubbing directions 9 and 10 of the substrates 1A and 1B are orthogonal to each other as shown in FIG. Laminated. At this time, the direction of the twist regulated by the rubbing process of the substrate 1A and the substrate 1B is to the left. A liquid crystal material (for example, MLC-2019 manufactured by Merck) whose chiral pitch was adjusted to 80 μm by adding a right-twisted chiral material (for example, R-811 manufactured by Merck) to the panel by a vacuum injection method was sealed. Polarizing plates were stuck on both sides of the liquid crystal panel produced as described above so as to be in a crossed Nicols state, and a normally white mode liquid crystal display element A was obtained.

On the other hand, the liquid crystal material (MLC-2019)
In order to know the pretilt angle when the two types of alignment films 12A and 12B are combined with each other,
A and 12B were used to prepare a homogeneous cell, and the measurement was performed by the crystal rotation method. The homogeneous cell is obtained by coating and curing each of the alignment films 12A and 12B, rubbing, and subjecting the alignment film Optmer AL3046 to a substrate 1B that has been subjected to photolithography in the same manner as described above with full exposure and full non-exposure. Thickness 2
The layers were bonded so as to have a thickness of 0 μm. A liquid crystal material (MLC-2019) containing no chiral material was sealed in this cell. The pretilt angle was about 6 ° in the non-exposed part 17 of Optmer AL3046, about 2 ° in the exposed part 16, and about 4 ° in AL5417. High pretilt alignment film Optmer AL3
It is conceivable that the exposed portion 16 of No. 046 was damaged due to direct contact with the alkali developing solution during the development processing in the photolithography process, and the pretilt angle was reduced.

FIG. 2 is a structural sectional view (sectional view taken along line FF of FIG. 1) showing the orientation of liquid crystal molecules of the liquid crystal display element A. Alignment film 1
The pretilt angle on the substrates 2A and 12B is higher in the non-exposed portion 17 than in the substrate 1A in the pre-tilt angle θP (H) of the substrate 1A, and conversely in the exposed portion 16 in the pre-tilt angle θP of the substrate 1B. The pretilt angle θP (M) of the substrate 1A is higher than (L). This liquid crystal display element A
Is the twist direction regulated by the rubbing process (left)
And the twisting direction (right) of the enclosed liquid crystal material is opposite, and the chiral pitch is relatively short, 80 μm.
The entire surface has a right-twisted spray TN orientation. as a result,
The direction in which the tilt of the liquid crystal molecules 13 of the midplane is reversed between the exposed portion 16 and the non-exposed portion 17 and the contrast becomes highest when an electric field is applied (hereinafter referred to as the principal viewing angle direction) is also changed between the exposed portion 16 and the non-exposed portion 17. In the opposite direction. As a result of applying a voltage to the liquid crystal display element A having both the upper and lower regions of the main viewing angle direction in each pixel and measuring the viewing angle characteristics of the contrast, a vertically symmetric equicontrast curve as shown in FIG. 6 was obtained. Was. CR5 in the figure has a black-and-white contrast ratio of 5,
CR10 indicates that the contrast ratio is 10.

Since the boundary between the regions of the liquid crystal display element A having different alignment states is within the pixel 2 having almost no irregularities, the boundary is straight without any disturbance, and the alignment on the signal line 14 in FIG. The orientation of each region was also very stable. Next, as a comparative example, a liquid crystal display element B was manufactured in the same manner as the liquid crystal display element A using a photomask having a stripe pattern pitch of 1/2. The liquid crystal display element B has boundaries of regions having different alignment states on the signal line. The vicinity of the signal line is a portion where the orientation tends to be unstable, for example, a portion where the step is shadowed during rubbing is not sufficiently processed. In the liquid crystal display element B, this portion had a boundary between regions having different alignment states, the alignment at the boundary portion was disturbed, and the alignment in each region was unstable.

In the description of this embodiment, the orientation division method is performed by patterning only the one-side substrate 1B and spraying.
As described in the example using the N orientation, both the substrates 1A and 1B are patterned so that the boundaries of the respective regions come within the pixel 2, mask rubbing is performed, and a type having a different twist direction or a spray having the same twist direction is used. Similar effects can be obtained with a TN alignment type alignment division panel.

An active matrix type liquid crystal display device according to a second embodiment will be described with reference to FIGS. As shown in FIG. 13, this active matrix type liquid crystal display element includes an active matrix array substrate 21B having a plurality of pixels 22 having a thin film transistor (TFT) element 23 as an active element, and a glass substrate 21A having a common electrode opposed thereto. The liquid crystal is sealed in.
A plurality of regions having different orientations of liquid crystal molecules are formed on the two substrates 21A and 21B, respectively. A region of one substrate 21A having different orientations of liquid crystal molecules includes a signal line 34 in a row direction, and the other substrate 21B has a different orientation. Include the signal lines 35 in the column direction. Thus, the intersection of the signal lines 34 and 35 in the row direction and the column direction of the active matrix substrate 21B is included in one of a plurality of different alignment regions formed by the substrates 21A and 21B.

Next, the manufacturing process of the active matrix type liquid crystal display device will be described. Pixels 22 are arranged in a glass substrate 21A on which a transparent electrode is formed as shown in FIG. 7 and in a matrix as shown in FIG.
An alignment film (for example, Optmer AL8534 manufactured by Nippon Synthetic Rubber Co., Ltd.) is formed on an active matrix array substrate 21B having a thin film transistor (TFT) element 23 formed thereon.
Was offset printed. With this printing method, the alignment film was uniformly formed on the entire screen. These two substrates 21A, 21
B was heated at 190 ° C. for 1 hour to cure the alignment film. Thereafter, both substrates 21A and 21B were subjected to a rubbing treatment with a rayon cloth in a rubbing direction 24 shown by arrows in FIGS.

Next, a positive type photoresist (for example, OFPR-5000) is applied to both substrates 21A and 21B by spin coating, and is applied on a hot plate at 90 ° C. for 1 hour.
Cured by heating for 0 minutes. At this time, the thickness of the photoresist was 1 μm. Next, the glass substrate 21A was irradiated with ultraviolet rays by using a stripe-shaped first photomask in which a light-shielding portion was formed at the same pitch 25 (about 300 μm) as the pixel pitch in the row direction. At this time, the first photomask was arranged such that the upper and lower halves of each pixel 22 were shielded by the light-shielding portion with the signal lines 34 in the row direction interposed every other row as shown in FIG. On the other hand, the substrate 21B was irradiated with ultraviolet rays using a stripe-shaped second photomask on which a light-shielding portion was formed at the same pitch 26 (about 100 μm) as the pixel pitch in the column direction. At this time, the second photomask was arranged such that the right and left halves of each pixel 22 were shielded by the light-shielding portion with the signal lines 35 in the column direction interposed every other column.

Thereafter, each of the substrates 21A and 21B is placed in an alkali developing solution (for example, NMD-3 manufactured by Tokyo Ohka Kogyo Co., Ltd.) for one hour.
It was immersed for a minute and rocked to dissolve the photoresist in the exposed area. As a result, a resist pattern as shown by hatched portions in FIGS. 9 and 10 was formed. Next, both substrates 21
A and 21B were each subjected to a rubbing process in a rubbing direction 27 opposite to that before the photolithography step. Then, it was immersed in acetone and rocked to remove the photoresist 28 in the non-exposed area. The rubbing patterns of both substrates 21A and 21B thus formed are as shown in FIGS.

The two substrates 21A and 21B are opposed to each other so that the electrode side faces each other so that the boundary in the rubbing direction on the substrate 21A coincides with the center of each pixel of the substrate 21B in the row direction. Laminated. As a result, the rubbing directions of the upper and lower substrates in each pixel of the panel were as shown in FIG. As shown in FIG.
4 different regions were formed in the pixel by the combination of the rubbing directions 24 and 27 of the substrate 21B and the rubbing directions 24 and 27 of the substrate 21B. A liquid crystal material (for example, MLC-2019 manufactured by Merck) was sealed in this panel by a vacuum injection method.
After annealing at 110 ° C. for 1 hour at a temperature sufficiently higher than the NI point of the liquid crystal material enclosed in the liquid crystal panel, the liquid crystal material was rapidly cooled. As a result, fine domains having different twist directions were mixed in each pixel.

A polarizing plate was attached to both sides of the liquid crystal panel manufactured as described above so as to be in a crossed Nicols state, and a normally white mode liquid crystal display element C was obtained. After applying a voltage of 5 V to the liquid crystal display element C for 5 minutes, the liquid crystal display element C was observed under a microscope with no voltage applied. As a result, it was confirmed that regions having different twist directions were arranged in a checkered pattern. When the panel was tilted and observed while a voltage of 2 V was applied, it was confirmed that four alignment states existed in each pixel 22 due to the difference in the main viewing angle direction. The boundaries between the regions extend almost straight up, down, left, and right, and the alignment state is as designed in almost all pixels, and a uniform alignment division pattern is obtained over the entire screen. This liquid crystal display element C
As a result of applying a voltage to and measuring the viewing angle characteristics of the contrast, an isocontrast curve as shown in FIG. 14 was obtained. In addition, no reversal from white to black level occurred within the range of the inclination angle of each direction up to 60 °.

For comparison, a liquid crystal display element D was formed using the same material and the same method as the liquid crystal display element C by using a photomask having a half pitch with respect to the pixel pitch in both the row and column directions.
Was prepared. The rubbing directions of the upper and lower substrates in each pixel of the liquid crystal display element D are as shown in FIG. In the liquid crystal display element D, the area of one region in the same alignment state is one fourth that of the liquid crystal display element C. Although the alignment state of the liquid crystal display element D immediately after the annealing treatment is almost the same as that of the liquid crystal display element C, a desired divided alignment can be obtained only by about 70% of all the pixels by applying a voltage of 5 V. Needed a higher voltage. When viewed from an oblique direction, the portions that are not in the desired alignment state have different brightness, and the unevenness appears to be emphasized. 7 V is applied to the liquid crystal display element D.
Did not result in a uniform orientation-divided panel over the entire surface.

On the other hand, the rubbing process is difficult to be uniform near the signal lines in the row and column directions due to the steps, but the intersections of the signal lines are more improper than those near the signal lines because some TFTs have larger steps. It tends to be in a uniform alignment state. Since the liquid crystal display element C includes this intersection portion in one area, the boundary between different alignment regions is in a pixel having almost no unevenness, and the boundary substantially coincides with the signal line in both the row and column directions. Since the alignment state in the vicinity of the boundary is more stable than in the case of the above, each region can also exist stably.
In addition, the liquid crystal display element C capable of increasing the region size is excellent because the orientation of the liquid crystal molecules becomes more stable, which leads to a larger monodomain.

Since a very high voltage is required to reverse the twist only by applying a voltage, it is desirable that each region contains a desired twist domain in order to obtain a desired orientation. There is a merit that one area can be enlarged also in terms of probability. In the description of this embodiment, the signal lines 3 are used for both the substrates 21A and 21B.
Although the stripe pattern is parallel to the lines 4 and 35, the same effect can be obtained if the intersection of the signal lines 34 and 35 in the row and column directions is included in one region.

An active matrix type liquid crystal display device according to a third embodiment will be described with reference to FIGS. As shown in FIG. 22, this active matrix type liquid crystal display element includes an active matrix array substrate 41B having a plurality of pixels 22 having a thin film transistor (TFT) element 43 as an active element, and a glass substrate 41A having a common electrode opposed thereto. The liquid crystal is sealed in.
A plurality of regions having different orientations of liquid crystal molecules are formed in stripes on both substrates 41A and 41B.
In addition, the intersection of the signal lines 54 and 55 in the row and column directions of the active matrix substrate 41B is defined by the two substrates 41A and 41B.
In one of a plurality of different alignment regions formed by the above, and the alignment region has a stripe shape substantially parallel to the signal line 54 in the row direction.

Next, the manufacturing process of this active matrix type liquid crystal display device will be described. As in the second embodiment, photolithography is performed in the steps shown in FIGS. As shown in FIGS. 16 and 17, a positive photoresist (OFPR-5000) is applied by spin coating to substrates 41A and 41B which have been subjected to a rubbing treatment after applying and curing an alignment film (Optmer AL-8534), Cured by heating on a plate at 90 ° C. for 10 minutes. Next, the glass substrate 41A was irradiated with ultraviolet rays by using a third photomask in the form of stripes in which the light-shielding portions were formed at a pixel pitch with a width 45 that is half the pixel width in the row direction. At this time, the third photomask was arranged such that the light-shielding portion shielded the light at the center of the pixel width in the row direction as shown in FIG. On the other hand, the substrate 41B was irradiated with ultraviolet rays using a first photomask having a stripe pattern having the same pitch in the row direction as used in manufacturing the liquid crystal display element C in the second embodiment. At this time, the first photomask was arranged such that the upper and lower halves of each pixel were shielded from light by interposing the signal lines 54 in the row direction at every other column.

Next, the same development processing as that of the second embodiment is applied to both substrates 41A and 41B as shown in FIGS.
A resist pattern as shown by the hatched portion was formed.
Further, after performing the rubbing process in the rubbing direction 47 opposite to that before the photolithography process, the photoresist 48 in the non-exposed portion was removed.
0 and FIG.

The two substrates 41A and 41B are positioned such that the centers of the regions in the rubbing directions different from each other on the substrate 41A are aligned with the center of each pixel of the substrate 41B in the row direction and the signal line so that the electrode sides face each other as shown in FIG. And bonded together via a spacer. As shown in FIG. 22, four rubbing directions 44 and 47 of the substrate 41A and rubbing directions 44 and 47 of the substrate 41B are combined into four pixels.
Two different areas were formed. A liquid crystal material (MLC-2019 manufactured by Merck) was sealed in this panel by a vacuum injection method. The liquid crystal material NI that encapsulates this liquid crystal panel
After annealing for 1 hour at 110 ° C., which is sufficiently higher than the temperature, the substrate was rapidly cooled. As a result, fine domains having different twist directions were mixed in each pixel 42.

A polarizing plate was attached to both sides of the liquid crystal panel manufactured as described above so as to be in a crossed Nicols state, and a normally white mode liquid crystal display element E was obtained. By applying a voltage of 5 V to the liquid crystal display element E, almost all pixels were in desired alignment states in four different alignment regions in each pixel 42, and a uniform alignment division pattern was obtained over the entire screen. . As a result of applying a voltage to the liquid crystal display element E and measuring the viewing angle characteristics of the contrast, an equal contrast curve similar to that of the liquid crystal display element C was obtained.

The liquid crystal display element E has regions of the same alignment state in the upper and lower pixels 42 sandwiching the signal line 54 in the row direction, and a large region can be formed in a portion where the alignment state tends to be unstable. Further, since the area of one region can be made larger than that of the liquid crystal display element C in which the boundary between the two substrates 41A and 41B intersects, each region can exist very stably.

In this embodiment, the case where each alignment region is parallel to the row direction has been described. However, the same effect can be obtained if the alignment regions are parallel to the column direction. Further, an orientation division panel of a type in which each substrate is subjected to mask rubbing a plurality of times, the twist direction of the entire region is the same, and the orientation direction is different.

[0045]

According to the active matrix type liquid crystal display device of the first aspect of the present invention, the vicinity of the signal line is a portion where the step is large and it is difficult to perform a uniform rubbing treatment, and the alignment state tends to be unstable. As described above, since the boundaries of the plurality of regions having different orientation directions or pretilt angles of the liquid crystal molecules do not overlap with the signal lines of the active matrix substrate, the boundaries can be present in a more stable alignment state in a pixel without unevenness. For this reason, the orientation of each region is also stabilized, and a uniform divided orientation over the entire screen can be obtained in a wide viewing angle panel having a plurality of orientation state regions in a pixel. Further, it is possible to obtain a stable and high-quality image display without causing uneven brightness unevenness in the screen.

According to the active matrix type liquid crystal display element of the second aspect of the present invention, since there is a TFT having a larger step at the intersection of the signal lines, the alignment state is more likely to be more non-uniform than near the signal lines. As described above, the intersection of the signal line in the row direction and the column direction of the active matrix substrate is included in one of the plurality of different alignment regions, so that the boundary between the different alignment regions is within a pixel having no unevenness. is there. For this reason, since the alignment state near the boundary becomes stable, each alignment region can also exist stably. As in the case of claim 1, a uniform divided alignment can be obtained over the entire screen, and uneven brightness can be obtained within the screen. It is possible to obtain a stable and high-quality image display without unevenness.

According to a third aspect of the present invention, the regions of one substrate having different alignment directions or pretilt angles of the liquid crystal molecules include the signal lines in the row direction, and the regions of the other substrate include the signal lines in the column direction. Since the four alignment regions having different directions are arranged in a checkered pattern, the boundaries of the alignment regions extend almost straight up, down, left, and right, and the alignment state is as designed in almost all pixels, and uniform alignment is achieved over the entire screen. A division pattern is obtained. In addition, since each alignment region includes the intersection of the signal line and the size of the region can be increased, the alignment of the liquid crystal molecules becomes more stable.

According to the active matrix type liquid crystal display element of the present invention, the intersection of the signal lines in the row direction and the column direction of the active matrix substrate is set within one of a plurality of different alignment regions. Therefore, the boundary of the different alignment regions is within the pixel without unevenness as in the second aspect. For this reason, since the alignment state near the boundary becomes stable, each alignment region can also exist stably. In addition, since the alignment region has a stripe shape substantially parallel to the signal line in either the row direction or the column direction, the upper and lower pixels sandwiching the signal line have regions of the same alignment state, and the alignment state becomes unstable. A large area can be formed in the easy part. For this reason, the area of one region can be made larger than that of a liquid crystal display element of a type in which the boundary between the two substrates intersects, so that each region can exist very stably.

[Brief description of the drawings]

FIG. 1 is a plan view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line FF of FIG. 2;

FIG. 3 is a process chart of a rubbing process of a glass substrate in the liquid crystal display device of the first embodiment.

FIG. 4 is a process chart of a rubbing process of the active matrix array substrate in the liquid crystal display device of the first embodiment.

FIG. 5 is a process chart of patterning the active matrix array substrate in the liquid crystal display device according to the first embodiment.

FIG. 6 is a viewing angle characteristic diagram of the liquid crystal display element of the first embodiment.

FIG. 7 is a process chart of a rubbing process of a glass substrate in a liquid crystal display device according to a second embodiment of the present invention.

FIG. 8 is a process chart of a rubbing process on an active matrix array substrate in a liquid crystal display device according to a second embodiment.

FIG. 9 is a process chart of patterning a glass substrate in the liquid crystal display device according to the second embodiment.

FIG. 10 is a process chart of patterning the active matrix array substrate in the liquid crystal display device according to the second embodiment.

FIG. 11 is a process diagram of a rubbing process on a glass substrate after a photolithography process in the liquid crystal display element of the second embodiment.

FIG. 12 is a process chart of a rubbing process of an active matrix array substrate after a patterning process in the liquid crystal display element of the second embodiment.

FIG. 13 is a plan view of a liquid crystal display device according to a second embodiment.

FIG. 14 is a viewing angle characteristic diagram of the liquid crystal display element of the second embodiment.

FIG. 15 is a plan view of a liquid crystal display device of a comparative example.

FIG. 16 is a process chart of a rubbing treatment of a glass substrate in a liquid crystal display device according to a third embodiment of the present invention.

FIG. 17 is a process chart of a rubbing process for an active matrix array substrate in the liquid crystal display device according to the third embodiment.

FIG. 18 is a process chart of patterning a glass substrate in the liquid crystal display device according to the third embodiment.

FIG. 19 is a process chart of patterning the active matrix array substrate in the liquid crystal display device according to the third embodiment.

FIG. 20 is a process chart of a rubbing process on a glass substrate after a patterning process in the liquid crystal display element of the third embodiment.

FIG. 21 is a process diagram of a rubbing process of an active matrix array substrate after a patterning process in a liquid crystal display device according to a third embodiment.

FIG. 22 is a plan view of a liquid crystal display device according to a third embodiment.

[Explanation of symbols]

1A, 21A, 41A Glass substrate 1B, 21B, 41B Active matrix array substrate 2, 22, 42 Pixel 3, 23, 43 Thin film transistor element 24, 44 Rubbing direction before photolithography process 5, 25, 46 Pitch in row direction 8, 28, 48 Photoresist 9 Rubbing direction of glass substrate 10 Rubbing direction of active matrix array substrate 11 Transparent electrode 12 Alignment film 13 Liquid crystal molecule 14, 34, 54 Signal line in row direction 26 Pitch in column direction 27, 47 Rubbing after patterning Direction 35,55 Column direction signal line

Claims (4)

[Claims] An active matrix type liquid crystal display device in which liquid crystal is sealed between an active matrix substrate having active elements in a plurality of pixels and a substrate having a common electrode facing each other, wherein at least one of the substrates has liquid crystal molecules. An active matrix type liquid crystal display element comprising a plurality of regions having different orientations or pretilt angles, and a boundary between the regions does not overlap with either a signal line in a row direction or a column direction of the active matrix substrate. . 2. An active matrix type liquid crystal display device in which liquid crystal is sealed between an active matrix substrate having an active element in a plurality of pixels and a substrate having a common electrode facing each other. It has a plurality of regions having different orientations or pretilt angles, and sets the intersection of the signal lines in the row direction and the column direction of the active matrix substrate to one of a plurality of different orientation regions formed by the two substrates. An active matrix type liquid crystal display device characterized by being included in a liquid crystal display. 3. A region of one substrate having different orientation directions or pretilt angles of liquid crystal molecules includes a row-direction signal line, and the other substrate includes a column-direction signal line,
3. The active matrix liquid crystal display device according to claim 2, wherein four alignment regions having different twist directions are arranged in a checkered pattern. 4. An active matrix type liquid crystal display device in which liquid crystal is sealed between an active matrix substrate having an active element in a plurality of pixels and a substrate having a common electrode facing each other. A plurality of regions having different orientations or pretilt angles are formed in a stripe shape, and an intersection of a signal line in a row direction and a column direction of the active matrix substrate is set to one of a plurality of different orientation regions formed by the two substrates. An active matrix type liquid crystal display device which is included in one alignment region and which has a stripe shape substantially parallel to the signal line in either the row direction or the column direction.