JPH08152635A - Production of liquid crystal display panel - Google Patents

Abstract

PURPOSE: To facilitate stages and to reduce a cost by forming resist patterns on an oriented film subjected to a rubbing treatment, then peeling these resist patterns and forming regions of different sizes in pretilt angle according to these resist patterns. CONSTITUTION: The oriented film 31 consisting of an orienting material of an org. system, such as polyimide, is formed on a substrate 11. Next, this film is subjected to the rubbing treatment in a specified direction. The rubbing is executed by progressing a rubbing roller 80 wound with buffing cloth of rayon, etc., while revolving the roller on the oriented film 31. Next, the resist 40 is applied on the oriented film 31 and the resist patterns are formed according to microregions by a photolithography technique. The resist 40 is removed by using an org. solvent. Two sheets of the substrates 11 subjected to the orientation treatment in such a manner are superposed on each other in such a manner that the rubbing treatment directions to the respective substrates are made perpendicular to each other. Liquid crystals are inserted between the substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display panel having a liquid crystal alignment state having different surfaces for each minute region.

[0002]

2. Description of the Related Art In a twisted nematic liquid crystal display panel, liquid crystals are twisted and aligned in a spiral shape from one substrate toward the other substrate, and liquid crystal molecules near the surfaces of the alignment films of both substrates are aligned. The orientations are almost perpendicular to each other. Further, liquid crystal molecules near the surface of the alignment film are pretilt with respect to each substrate. The alignment direction and pretilt direction of the liquid crystal molecules near the surfaces of the respective substrates are determined according to the rubbing direction of the alignment films on both substrates. The alignment direction of the liquid crystal can also be controlled by oblique vapor deposition of the alignment film.

In such a twisted nematic liquid crystal display panel, the transmittance of incident light can be controlled by controlling the voltage applied to the liquid crystal, and gradation display from the bright state to the dark state can be performed. However, since the brightness of each gradation changes depending on the viewing direction of the screen, there is a problem that the viewing angle range in which the display can be accurately recognized is narrow. That is, when viewed from a certain direction, the entire display is whitish, when viewed from the opposite direction, the entire display is blackened, and gradation inversion occurs.

The above is due to the asymmetry of the alignment state of the liquid crystal. The rising direction of liquid crystal molecules when a voltage is applied to the liquid crystal is determined by the pretilt direction. Further, the rising angle depends on the magnitude of the applied voltage, and by controlling the magnitude of this voltage, the gradation display described above can be performed. The movement of liquid crystal molecules due to the applied voltage is small near the surfaces of both substrates and large in the intermediate region between both substrates. Therefore, the rising angle of the liquid crystal molecules mainly existing in the intermediate region of both substrates with respect to the substrate is
Contributes to the brightness of the display. In the state where the liquid crystal molecules in this region stand up at a certain angle from the substrate, that is, in the halftone display state, when the liquid crystal display panel is observed from the rising direction of the liquid crystal molecules, the screen looks whitish and from the opposite direction. It looks black when observed.

In order to solve such a problem of the viewing angle characteristic, Japanese Patent Publication No. 58-43723 proposes a structure in which regions in which the alignment treatment directions of the alignment film are different from each other are formed with a fine pitch. FIG. 2 shows the above Japanese Patent Publication No. 58-4372.
The structure of the cross section of the liquid crystal panel based on Japanese Patent No. 3 is shown. Figure 2
In the structure, the minute regions A and B have different alignment treatment directions of the alignment film. Therefore, the small area A,
In B, the rising direction of liquid crystal molecules when a voltage is applied is different,
The observer recognizes the visual angle characteristics of each minute region after averaging them. As a result, the viewing angle characteristics are improved.

In order to form such regions having different alignment treatment directions on the same substrate, for example, a resist is applied on the alignment film which has been rubbed in one direction and patterned into a predetermined shape by a photolithography technique. However, it is necessary to perform a step of performing rubbing again in the direction opposite to the rubbing direction of the first time and removing the resist. In this step, since the alignment treatment directions are divided, it is necessary to perform rubbing treatment twice for one substrate.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 5-210099, by forming the alignment film partially in a two-layer structure according to a predetermined pattern, minute regions A having different pretilt angles on the same substrate, It is proposed to form B. According to this proposal, it is not necessary to divide the alignment treatment direction, and the same effect of improving the viewing angle characteristics can be obtained by rubbing once for one substrate. FIG. 3 shows a cross-sectional structure of a liquid crystal panel based on the above-mentioned Japanese Patent Laid-Open No. 5-210099. In FIG. 3, the alignment film 3 of both substrates 11 and 12
Reference numerals 1 and 32 have a two-layer structure of a first-layer orientation agent layer 51 and a second-layer orientation agent layer 52.

In the alignment film 31 of the lower substrate 11, the second alignment agent layer 52 is opened in the minute region B,
The first orientation layer 51 is exposed. In the minute area A, the second orientation agent layer 52 is exposed. Although the minute regions A and B have the same alignment direction and pretilt direction, the first alignment agent layer 51 and the second alignment agent layer 52 are
Different pretilt angles α ° and β °
Since (<α °) is given, the pretilt angle in the minute region A is α ° and the pretilt angle in the minute region B is β ° in the vicinity of the alignment film surface of the lower substrate.

On the other hand, in the alignment film 32 of the upper substrate 12, in the minute area A, the second alignment agent layer 52 is opened and the first alignment agent layer 51 is exposed. In the minute region B, the second alignment agent layer is exposed. Therefore, in the vicinity of the surface of the alignment film on the upper substrate, a small area A
The pretilt angle in the area B is β °, and the pretilt angle in the minute area B is α °.

In the structure shown in FIG. 3, the alignment direction of the liquid crystal is twisted in both the minute regions A and B from the vicinity of the alignment film surface of the lower substrate to the vicinity of the alignment film surface of the upper substrate. Further, the pretilt directions near the surfaces of both substrates are opposite to each other, and during that time, spray deformation is performed so that the angle with respect to the plane parallel to the substrate surfaces gradually changes. That is, as a whole, it is in a splay type twisted nematic type alignment state. When attention is paid to each of the minute regions A and B, the magnitudes of the pretilt angles of the liquid crystal molecules near the alignment film surfaces of the upper and lower substrates are different. In a liquid crystal panel of splay orientation in which the magnitudes of the pretilt angles on the upper and lower substrates are different, when a voltage is applied, the liquid crystal rises according to the pretilt direction with the larger pretilt angle. That is, in the minute region A, the rise occurs according to the pretilt direction near the alignment film surface of the lower substrate, and in the minute region B, the rise occurs according to the pretilt direction near the alignment film surface of the upper substrate. In this way, the rising directions of the liquid crystal molecules when a voltage is applied are different in the minute regions A and B, and the viewing angle characteristics of the respective minute regions are averaged and recognized by the observer. That is, JP-A-5-21009
The structure according to Japanese Patent Publication No. 9 can also obtain the same effect as the structure according to Japanese Patent Publication No. 58-43723.

Such a structure in which the magnitude of the pretilt angle is different for each minute region can be formed by a series of alignment treatment methods shown in FIG. FIG. 4A shows the first layer of the aligning agent layer 51 formed, and FIG. 4B shows the second layer of the aligning agent layer 52 formed.
(C) shows the second alignment film layer 52 according to the pattern formed of the resist material 40 by the photolithography technique.
Is partially removed, FIG. 4 (d) is where the resist pattern is removed, and FIG. 4 (e) is where the rubbing process is performed.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 6-148641, only the alignment film on one of the substrates has a two-layer structure partially according to a predetermined pattern, and the magnitudes of the pretilt angles are different between the minute regions A and B. Thus, it is proposed that the alignment film on the other substrate be subjected to uniform pretilt as a structure consisting of a single layer. FIG. 7 shows a cross-sectional structure of a liquid crystal panel based on the above-mentioned JP-A-6-148641.

In FIG. 7, the alignment film 31 of the lower substrate 11 is formed.
Is configured similarly to the case of the liquid crystal panel shown in FIG.
It has been oriented. Therefore, in the vicinity of the alignment film surface of the lower substrate, the pretilt angle in the minute area A is α °,
The pretilt angle in the minute area B is β °.

On the other hand, the alignment film 32 of the upper substrate 12 is composed of a single layer and is uniformly aligned. In the vicinity of the alignment film surface of the upper substrate, the pretilt angle is γ ° (α °> γ
°> β °).

In the structure shown in FIG. 7, as in the case of the liquid crystal panel shown in FIG. 3, the liquid crystal 20 is in the splay type twisted nematic type alignment state as a whole. Focusing on each of the microscopic regions A and B, since the magnitude of the pretilt angle of the liquid crystal molecules near the alignment film surfaces of the upper and lower substrates is different, in the microscopic region A, the alignment film surface of the lower substrate is According to the pretilt direction in the vicinity, in the minute area B, it rises according to the pretilt direction in the vicinity of the alignment film surface of the upper substrate. In this way, the rising directions of the liquid crystal molecules when a voltage is applied are different in the minute regions A and B, and the viewing angle characteristics of the respective minute regions are averaged and recognized by the observer. That is, JP-A-6-14
Even with the structure according to Japanese Patent No. 8641, there is a problem with Japanese Patent Laid-Open No. 5-210009.
It is possible to obtain the same effect as that of the structure according to Japanese Patent Publication No. 9 or the structure according to Japanese Patent Publication No. 58-43723.

[0016]

As described above, for the purpose of improving the viewing angle characteristics of a liquid crystal panel, a liquid crystal display in which an alignment film is subjected to an alignment treatment so that the alignment state of the liquid crystal is different for each minute region. In order to manufacture a panel, conventionally, it was necessary to form a finely patterned alignment film having a two-layer structure as described above. For this purpose, the first layer of the alignment film material is applied, the second layer of the alignment film material is applied, and a predetermined resist pattern is formed by the photolithography technique.
The aligning agent layer of the layer is partially removed according to the resist pattern,
There is a problem that many steps are required such as resist stripping.

[0017]

According to the method for manufacturing a liquid crystal display panel of the present invention, a resist pattern is formed on a rubbing-treated alignment film and then the resist pattern is peeled off. It is based on the newly found experimental fact that regions having different corner sizes can be formed. That is, the method for manufacturing a liquid crystal display panel according to the present invention is directed to the alignment films 31 and 3
First and second opposing substrates 11, 12 provided with 2
And a nematic liquid crystal 20 in a splay-type twisted nematic alignment state inserted between the substrates. The alignment film of at least one of the substrates has a large pretilt angle of the liquid crystal near the alignment film surface for each minute region. A method for manufacturing a liquid crystal display panel, wherein the liquid crystal display panel is aligned so that
A step of applying a resist 40 after rubbing the alignment film 31 or 32 of at least one of the substrates, and exposing the resist 40 through a mask having a predetermined pattern, and then removing the exposed or unexposed part of the resist 40 with a developer. And a step of removing the unexposed portion or the exposed portion of the resist 40 with a stripping solution, the step of forming a fine alignment region.

In the method of manufacturing a liquid crystal display panel according to the present invention, the pretilt angle of the liquid crystal near the surface of the alignment film in each of the minute regions of the alignment films 31 and 32 of the first and second substrates by the above steps. Regions having a large pretilt angle near the surface of the alignment film 31 of the first substrate and a region having a small pretilt angle near the surface of the alignment film 32 of the second substrate. , Again
Of the first substrate 11 and the second substrate 12 such that a region having a small pretilt angle near the surface of the alignment film 31 of the second substrate faces a region having a large pretilt angle near the surface of the alignment film 32 of the second substrate. Is characterized by performing a step of overlapping.

In the method of manufacturing a liquid crystal panel according to the present invention, the pretilt angle of the liquid crystal 20 near the surface of the alignment film in the microscopic region of only the alignment film of one substrate (for example, the alignment film 31 of the first substrate 11). Of the liquid crystal 20 in the vicinity of the surface of the alignment film is uniform in the alignment film of the other substrate (for example, the alignment film 32 of the second substrate 12). You may. in this case,
Of the pretilt angles near the surface of the alignment film 31 of the first substrate 11, the larger one is α ° and the smaller one is β °,
When the pretilt angle in the vicinity of the surface of the alignment film 32 of the second substrate 12 is γ °, the relationship of α>γ> β can be established. That is, it is possible to obtain a structure in which the alignment state of the liquid crystal is different for each minute region, and it is not necessary to partially form the alignment film into a two-layer structure so as to correspond to the minute region. Therefore, cost reduction can be achieved.

[0020]

【Example】

[Embodiment 1] FIG. 1 shows a liquid crystal panel 1 according to an embodiment of the present invention.
00, and polarizing plates (not shown) are arranged on both sides of the liquid crystal panel 100. The liquid crystal panel 100 is one in which a liquid crystal 20 is sealed between a pair of transparent substrates 11 and 12. A pixel electrode 71 and an alignment film 31 are provided on the inner surface of the lower substrate 11 shown in FIG. The pixel electrode 71 is connected to an active matrix circuit (not shown). A common electrode 72 of ITO is provided inside the upper substrate. Common electrode 7
An alignment film 32 is provided on the surface 2.

FIG. 5 shows a substrate orientation treatment method in this embodiment. Although FIG. 5 shows only the substrate 11 of FIG. 1, it is needless to say that the substrate 12 can be similarly subjected to the alignment treatment. First, as shown in FIG. 5A, an alignment film 31 made of an organic alignment agent such as polyimide is formed on the substrate 11.
To form. Next, as shown in FIG. 5B, a rubbing process is performed in a fixed direction. The rubbing is performed by advancing the rubbing roller 80 wound with a buff cloth such as rayon on the alignment film 31 while rotating. Next, as shown in FIG. 5C, a resist 40 is applied on the alignment film 31 and a resist pattern is formed in accordance with a minute region by a photolithography technique. Next, as shown in FIG. 5D, the resist is removed using an organic solvent. In this example, Toray K-100b was used as the aligning agent, and ethyl lactate was used to remove the resist.

As shown in FIG. 6, the substrates thus oriented are stacked so that the rubbing directions of the substrates are substantially perpendicular to each other, and a counterclockwise chiral agent is placed between the substrates. Added nematic liquid crystal 20
Inserted. At this time, the alignment film 3 shown in FIG.
The region where the resist 40 was present on the surface 1 and the region where the resist 40 was not present on the alignment film 32 face each other, and the region where the resist 40 was not present on the alignment film 31 and the region where the resist 40 was present on the alignment film 32 were Both substrates are stacked so that they face each other. The liquid crystal 20 is twisted and aligned by approximately 90 degrees between the substrates 11 and 12 according to the above-described alignment treatment.
In addition, the spray deformation is performed such that the pretilt direction with respect to a plane parallel to the substrate surface gradually changes from one substrate to the other substrate and the pretilt directions near both substrate surfaces are opposite to each other. . That is, as a whole, it is in a splay type twisted nematic type alignment state.

In this liquid crystal display panel, the pretilt angles on the surfaces of both substrates were measured. The measurement result of the pretilt angle is shown in (c) of FIG.
5 degrees in the area where there was, 1 in the area where there was no resist 40
It was found that the magnitude of the pretilt angle was different.

As described above, in this embodiment, the alignment state of the liquid crystal 20 is different for each of the minute regions A and B shown in FIG. That is, in the small area A, the pretilt angle near the surface of the lower substrate 11 is larger than the pretilt angle near the surface of the upper substrate 12, and in the small area B near the surface of the upper substrate 12. The pretilt angle is larger than the pretilt angle near the surface of the substrate 11 on the lower side. Then, at the time of applying the voltage, for each of the minute regions A and B,
It was confirmed that the liquid crystal rises according to the pretilt direction with the larger pretilt angle on the surfaces of both substrates. That is, in the minute area A, the rise occurs according to the pretilt direction near the surface of the lower substrate 11, and in the minute area B, the rise occurs according to the pretilt direction near the surface of the upper substrate 12. In this way, the rising directions of the liquid crystal molecules when a voltage is applied are different in the minute areas A and B, and the asymmetrical viewing angle characteristics of the respective minute areas are averaged and recognized by the observer. The viewing angle characteristic that the display can be recognized from a wider viewing angle range than the conventional one was obtained.

[Embodiment 2] SE-7210 manufactured by Nissan Chemical Industries, Ltd. is used as an alignment film material, and a structure having different pretilt angles for each minute region can be obtained by the same steps as in Embodiment 1. It was confirmed. In this case, FIG.
The pretilt angle in the region where the resist 40 is on the alignment film 31 shown in (c) is 4 degrees, and in the other regions it is 7 °.
It was degree. Therefore, the rising directions of the liquid crystal molecules when a voltage is applied are different in each of the minute regions A and B, and the asymmetrical viewing angle characteristics of the respective regions are averaged. The viewing angle characteristic that the display can be recognized from the range was obtained.

[Example 3] RN-715 manufactured by Nissan Chemical Industries, Ltd. was used as the alignment film material, and a structure having different pretilt angles for each minute region was obtained by the same steps as in Example 1. It was confirmed. In this case, FIG.
The pretilt angle in the region where the resist 40 is on the alignment film 31 shown in (c) is 9 degrees, and is 1 in the other regions.
It was twice. Therefore, the rising directions of the liquid crystal molecules when a voltage is applied are different in each of the minute regions A and B, and the asymmetrical viewing angle characteristics of the respective regions are averaged. The viewing angle characteristic that the display can be recognized from the range was obtained.

[Embodiment 4] FIG. 8 shows a liquid crystal panel 100 according to an embodiment of the present invention, and polarizing plates (not shown) are arranged on both sides of the liquid crystal panel 100. Liquid crystal panel 10
0 is a liquid crystal 20 enclosed between a pair of transparent substrates 11 and 12. A pixel electrode 71 and an alignment film 31 are provided on the inner surface of the lower substrate 11 shown in FIG. The pixel electrode 71 is connected to an active matrix circuit (not shown). A common electrode 72 of ITO is provided inside the upper substrate. The alignment film 32 is provided on the common electrode 72.

The alignment treatment method for the first substrate 11 in this embodiment is exactly the same as the alignment treatment method for the liquid crystal panel of Embodiment 1 shown in FIG. On the other hand, the method of aligning the second substrate 12 is simpler than this.
That is, after the alignment film 32 made of an organic alignment agent such as polyimide is formed on the substrate 12, a rubbing process is performed in a fixed direction. As the alignment film material in this embodiment, as the alignment film 31 of the first substrate 11, K-100b manufactured by Toray Industries, Inc. is used as in the first embodiment, and the alignment film 32 of the second substrate 12 is used.
As the product, SE-7331 manufactured by Nissan Chemical Industries, Ltd. was used.

In the same manner as in Example 1, the substrates thus oriented were stacked, and a counterclockwise chiral agent-added nematic liquid crystal 20 was inserted between the substrates. The liquid crystal 20 is in a splay type twisted nematic type alignment state as a whole.

In this liquid crystal display panel, the pretilt angles on the surfaces of both substrates were measured. The measurement result of the pretilt angle is the same as that of the first embodiment for the first substrate 11,
As shown in FIG. 5C, it was 5 degrees in the region where the resist 40 was present on the alignment film, and 1 degree in the region where the resist 40 was not present. On the other hand, for the second substrate, it was 3 degrees uniformly.

As described above, in this embodiment, the alignment state of the liquid crystal 20 is different for each of the minute regions A and B shown in FIG. That is, in the small area A, the pretilt angle near the surface of the lower substrate 11 is larger than the pretilt angle near the surface of the upper substrate 12, and in the small area B near the surface of the upper substrate 12. The pretilt angle is larger than the pretilt angle near the surface of the substrate 11 on the lower side. Then, at the time of applying the voltage, for each of the minute regions A and B,
It was confirmed that the liquid crystal rises according to the pretilt direction with the larger pretilt angle on the surfaces of both substrates. That is, in the minute area A, the rise occurs according to the pretilt direction near the surface of the lower substrate 11, and in the minute area B, the rise occurs according to the pretilt direction near the surface of the upper substrate 12. In this way, the rising directions of the liquid crystal molecules when a voltage is applied are different in the minute areas A and B, and the asymmetrical viewing angle characteristics of the respective minute areas are averaged and recognized by the observer. The viewing angle characteristic that the display can be recognized from a wider viewing angle range than the conventional one was obtained.

[0032]

As described above, according to the present invention,
A liquid crystal panel that has been subjected to an alignment treatment in which the alignment state of liquid crystal is different for each minute region does not have to have a two-layer structure for the alignment film to correspond to the minute region, and only once for one substrate. Can be realized by rubbing. Therefore, the process is facilitated and cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a conventional liquid crystal display panel in which an alignment state is different for each minute region.

FIG. 3 is a cross-sectional view showing another structure of a conventional liquid crystal display panel in which the alignment state is different for each minute region.

4 (a) to 4 (e) are cross-sectional views showing an alignment treatment step of the liquid crystal display panel of FIG.

5A to 5D are cross-sectional views showing an alignment treatment of the liquid crystal display panel of FIG.

6 is a diagram showing a rubbing direction of the substrate of FIG.

FIG. 7 is a cross-sectional view showing another structure of a conventional liquid crystal display panel in which the alignment state is different for each minute region.

FIG. 8 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 11, 12 substrate 20 liquid crystal 31, 32 alignment film layer 40 resist material 51 first layer alignment agent layer 52 second layer alignment agent layer 71 pixel electrode 72 common electrode 80 rubbing roller 100 liquid crystal panel

Claims (2)

[Claims] 1. Alignment of at least one substrate, which comprises first and second opposing substrates provided with alignment films and nematic liquid crystals in a splay type twisted nematic alignment state inserted between the substrates. A method for manufacturing a liquid crystal display panel, wherein the film is subjected to an alignment treatment such that the size of the pretilt angle of the liquid crystal in the vicinity of the alignment film surface is different for each minute region, the method comprising: rubbing the alignment film on at least one of the substrates. A step of applying a resist, a step of exposing the resist through a mask having a predetermined pattern and then removing the exposed or unexposed portion of the resist with a developer, and an unexposed or exposed portion of the resist being removed with a peeling solution. A method of manufacturing a liquid crystal panel, comprising the step of forming a fine alignment region including the step of: 2. The alignment films of the first and second substrates are subjected to alignment treatment so that the magnitude of the pretilt angle of liquid crystal near the alignment film surface is different for each minute region, and then the alignment of the first substrate is performed. The region with a large pretilt angle near the surface of the film is the second
A region having a small pretilt angle in the vicinity of the surface of the alignment film of the first substrate and a region having a small pretilt angle in the vicinity of the surface of the alignment film of the first substrate have a large pretilt angle in the vicinity of the surface of the alignment film of the second substrate. 2. The method of manufacturing a liquid crystal panel according to claim 1, wherein the step of stacking the first substrate and the second substrate is performed so as to face the area having the.