JP2853629B2 - Liquid crystal alignment film material and method of manufacturing liquid crystal display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment film material suitable for an alignment film of a liquid crystal display panel and a method of manufacturing a liquid crystal display panel, and more particularly to a liquid crystal alignment film having a surface in which the alignment state of liquid crystal is different for each minute region. The present invention relates to a material and a method for manufacturing a liquid crystal display panel.

[0002]

2. Description of the Related Art Liquid crystal display panels have characteristics such as thinness and light weight and low power consumption, and are now widely used. This liquid crystal display panel has a structure in which liquid crystal is injected between two upper and lower transparent substrates having electrodes, controls the voltage applied to the electrodes, and changes the orientation of the liquid crystal by the action of an electric field. Display is performed by utilizing changes in optical properties.

[0003] The operation principle of a liquid crystal display panel utilizes a change in liquid crystal alignment due to the action of an electric field.
The uniformity and stability of the liquid crystal alignment are particularly important.

Conventionally, oblique evaporation of silicon oxide or rubbing of an organic polymer film has been used as a means for obtaining uniformity of liquid crystal alignment. Film is the mainstream.

[0005] Among these organic polymer films, a polyimide film is particularly excellent in consideration of heat resistance and insulation.

As the polyimide film material, a polyimide polymer compound or a polyamic acid polymer compound is mainly used. Each of them is used as a solvent dissolved in an appropriate solvent, but the former (polyimide-based polymer compound) is a polyimide-based polymer compound which is soluble in a solvent by introducing a polar group, and after applying the solvent, , A solvent that evaporates upon firing to produce a polyimide film (soluble polyimide type), and the latter (polyamic acid-based polymer compound) is a polyamic acid-based polymer compound that is a precursor of polyimide. After applying a solvent, a dehydration reaction is caused by firing to imidize the polyamic acid to produce a polyimide film (polyamic acid type).

In a liquid crystal display panel of the most commonly used twisted nematic type (also referred to as a “twisted nematic type”), the liquid crystal is twisted and aligned in a spiral form from one substrate to the other. Thus, the alignment of the liquid crystal molecules near the surface of the alignment film of both substrates is substantially perpendicular to each other.

The liquid crystal molecules near the surface of the alignment film are pretilted with respect to each substrate.

[0009] The orientation direction and pretilt direction of the liquid crystal molecules in the vicinity of each substrate surface are determined according to the rubbing direction with respect to the alignment films of both substrates as described above.

In such a twisted nematic liquid crystal display panel, by controlling the voltage applied to the liquid crystal, the transmittance of incident light can be controlled, and gradation can be displayed from a bright state to a dark state.

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 display becomes whitish as a whole, and when viewed from the opposite direction, the display is entirely blackened or the gradation is inverted.

The above-described viewing angle dependence of the liquid crystal display panel is caused by the asymmetry of the alignment state of the liquid crystal.

The direction in which liquid crystal molecules rise when a voltage is applied to the liquid crystal is determined by the direction of pretilt.
Also, the angle at which the liquid crystal molecules rise depends on the magnitude of the voltage applied to the electrodes, and the above-described gradation display can be performed by controlling the magnitude of this voltage.

The movement of the liquid crystal molecules due to the applied voltage is small near the surfaces of the two substrates and large in the intermediate region between the two substrates.
Therefore, mainly of the liquid crystal molecules existing in the intermediate region between the two substrates,
The rising angle with respect to the substrate contributes to the brightness of the display.

In a state where the liquid crystal molecules in this region rise from the substrate at a certain angle, that is, in a halftone display state, when the liquid crystal display panel is observed from the direction in which the liquid crystal molecules rise, the screen looks blackish. When viewed from the opposite direction, it appears white.

In order to solve such a problem of the viewing angle characteristics, for example, Japanese Patent Publication No. 58-43723 proposes a structure in which regions in which the alignment treatment directions of the alignment films are different from each other are formed at a fine pitch. I have. That is, the gazette states that
In a liquid crystal element in which an alignment performance is imparted to an inner surface and a nematic liquid crystal is sandwiched between a pair of transparent electrode plates facing each other such that the alignment performance is substantially orthogonal to each other, the alignment performance on the liquid crystal plate surface is visually checked. A liquid crystal element has been proposed in which liquid crystal elements are alternately provided in a reverse direction at a fine pitch that cannot be distinguished.

FIG. 5 shows a cross-sectional structure of a conventional liquid crystal display panel based on the proposal of Japanese Patent Publication No. 43723/1983. In FIG. 5, 11 and 12 are substrates, 20 is a liquid crystal,
Reference numerals 31 and 32 denote alignment films, 71 denotes a pixel electrode, 72 denotes a common electrode, and 100 denotes a liquid crystal display panel.

Referring to FIG. 5, this conventional liquid crystal display panel has a structure in which each of minute regions A and B has a different alignment processing direction of an alignment film. Therefore, the minute areas A and B
, The rising direction of the liquid crystal molecules when a voltage is applied is different, so that the observer can recognize and average the viewing angle characteristics of each minute area. As a result, an improvement in viewing angle characteristics can be obtained.

In order to form such regions having different orientation directions on the same substrate, for example, a resist is applied on an orientation film which has been subjected to a rubbing process in one direction, and is formed into a predetermined shape by a photolithography technique. Patterning,
It is necessary to perform a process of performing rubbing again in a direction opposite to the first rubbing direction and removing the resist. In this step, since the orientation direction is divided, two rubbing processes are required for one substrate.

Further, in order to eliminate the problem that many steps are required to perform the alignment treatment so that the alignment state of the liquid crystal is different for each minute region, both substrates are subjected to a single rubbing treatment step. As a device for realizing a liquid crystal display device having two micro regions having different alignment states, for example, Japanese Patent Application Laid-Open No. H5-210099 discloses a method in which an alignment film is partially formed into a two-layer structure according to a predetermined pattern. There has been proposed a liquid crystal display device in which minute regions A and B having mutually different pretilt angles are formed on a substrate.
That is, according to the liquid crystal display device proposed in the publication,
There is no need to divide the orientation direction, and one substrate
The same effect of improving the viewing angle characteristics can be obtained by rubbing a number of times.

FIG. 6 shows a cross-sectional structure of a liquid crystal display panel based on the above-mentioned Japanese Patent Application Laid-Open No. 5-210099.

Referring to FIG. 6, the alignment films 31 and 32 of both substrates 11 and 12 have a two-layer structure of a first alignment film layer 51 and a second alignment film layer 52.

The alignment film 31 of the lower substrate 11 has an opening in the second alignment film layer 52 in the minute region B.
The first alignment film layer 51 is exposed, and in the minute region A, the second alignment film layer 52 is exposed.

Although the minute regions A and B have the same orientation direction and pretilt direction, the first and second orientation film layers 51 and 52 have different pretilt angles α ° and β ° respectively. ° (<α °), the lower substrate 11
In the vicinity of the surface of the alignment film 31, the pretilt angle in the minute area A is α °, and the pretilt angle in the minute area B is β °.

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

In the structure shown in FIG. 6, the orientation of the liquid crystal is changed from the vicinity of the surface of the alignment film 31 of the lower substrate 11 to the vicinity of the surface of the alignment film 32 of the upper substrate 12 in both the minute regions A and B. Twisted. In addition, both substrates 1
The pretilt directions near the surfaces 1 and 12 are opposite to each other, and the splay deformation is performed so that the angle with respect to a plane parallel to the substrate surface gradually changes between them. That is, the whole is in a splay type twisted nematic type alignment state.

Focusing on the minute regions A and B, the magnitude of the pretilt angle of the liquid crystal molecules near the surfaces of the alignment films 32 and 31 of the upper and lower substrates 12 and 11 is different. In a splay-aligned liquid crystal display panel in which the magnitudes of the pretilt angles of the upper and lower substrates 12 and 11 are different, when a voltage is applied, the liquid crystal rises according to the pretilt direction having the larger pretilt angle.

That is, in the minute region A, the pretilt direction near the surface of the alignment film 31 of the lower substrate 11 is determined, and in the minute region B, the pretilt direction near the surface of the alignment film 32 of the upper substrate 12 is determined. Stand up, respectively.

As described above, the rising directions of the liquid crystal molecules at the time of applying a voltage are different between the minute regions A and B, and the observer recognizes the viewing angle characteristics of each minute region by averaging. That is, even with the structure disclosed in JP-A-5-210099, it is possible to obtain the same operation and effect as the structure described in JP-B-58-43723.

Such a structure in which the size of the pretilt angle differs for each minute region can be formed by a series of alignment treatment methods shown in the sectional views of the steps in FIG.

FIG. 7A is a view showing a state in which the first alignment film layer 51 is formed on the pixel electrode 71. FIG.
FIG. 7B is a diagram in which a second alignment film layer 52 is formed, and FIG. 7C is a diagram in which a second alignment film layer 52 is formed according to a pattern formed of a resist material 40 by photolithography.
7D is a view showing a state in which the resist pattern is partially removed, and FIG. 7D is a view showing a state in which the resist pattern is removed.
(E) is a diagram schematically showing a state in which a rubbing process is performed by the rubbing roller 80.

Japanese Unexamined Patent Publication (Kokai) No. 6-148641 discloses that only the orientation film of one substrate is partially formed into a two-layer structure according to a predetermined pattern, and the magnitude of the pretilt angle is mutually different for each of the minute regions A and B. 2. Description of the Related Art A liquid crystal display panel has been proposed in which an alignment process is performed differently, and an alignment process is performed so that the alignment film of the other substrate is uniformly pretilted as a single-layer structure. FIG.
1 shows a cross-sectional structure of a liquid crystal display panel based on Japanese Patent Application Laid-Open Publication No. H10-209,878.

Referring to FIG. 8, alignment film 31 of lower substrate 11 has the same configuration as that of the liquid crystal display panel shown in FIG. 6, and has been subjected to alignment processing. Therefore, near the surface of the alignment film 31 of the lower substrate 11, the pretilt angle in the minute area A is α °, and the pretilt angle in the minute area B is β °.
It has become.

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 surface of the alignment film 32 of the upper substrate 12, the pretilt angle is γ °.
(Α °> γ °> β °).

In the structure shown in FIG. 8, as in the case of the liquid crystal display panel shown in FIG. 6, the liquid crystal 20 is in a splayed twisted nematic alignment state as a whole. Focusing on each of the minute regions A and B, the magnitude of the pretilt angle of the liquid crystal molecules near the surfaces of the alignment films 32 and 31 of the upper and lower substrates 12 and 11 is different. The micro region B rises in accordance with the pretilt direction near the surface of the alignment film 32 of the upper substrate 12 according to the pretilt direction near the surface of the alignment film 31 of the substrate 11.

As described above, the rising directions of the liquid crystal molecules upon application of a voltage are different between the minute regions A and B, and the observer recognizes the viewing angle characteristics of each minute region by averaging. That is, the structure according to Japanese Patent Application Laid-Open No. 6-186441 can provide the same effect as the structure according to Japanese Patent Application Laid-Open No. 5-210099 or the structure according to Japanese Patent Publication No. 58-43723.

[0037]

As described above, the purpose of the present invention is to improve the viewing angle characteristics of a liquid crystal display panel, and a liquid crystal in which an alignment film is subjected to an alignment treatment so that the alignment state of the liquid crystal is different in each minute region. Conventionally, to manufacture display panels,
As described above, it was necessary to form an alignment film that was finely patterned in a two-layer structure.

For this purpose, a first layer of an alignment film material is applied,
Many steps are required, such as application of a second layer of alignment film material, formation of a predetermined resist pattern by photolithography technology, partial removal of the second layer of alignment film according to the resist pattern, and resist stripping. There was a problem.

Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and realizes a structure in which the alignment state of the liquid crystal is different for each minute region with less man-hour than the conventional technology. It is an object of the present invention to provide a liquid crystal display panel that achieves a wide viewing angle.

[0040]

In order to achieve the above object, a liquid crystal alignment film material according to the present invention comprises at least polyimide or a polyimide precursor, a photocrosslinking agent, and a low molecular compound having a long-chain alkyl group. mixture only free, photosensitive
The pretilt angle can be selectively adjusted for each minute area using
The alignment treatment can be performed differently .

This mixture is dissolved in an organic solvent such as N-methyl-2-pyrrolidinone, applied to a substrate, and dried by heating.

In the liquid crystal alignment film material according to the present invention,
As the photocrosslinking agent, a compound having at least two azide groups can be used, and as the low-molecular compound having a long-chain alkyl group, a compound having an unsaturated bond such as a long-chain alkyl acrylate can be used.

Further, according to the present invention, the first and second opposed substrates (1) provided with alignment films (31, 32; see FIG. 1) are provided.
1, 12) and a nematic liquid crystal (20) in a splay type twisted nematic type alignment state inserted between substrates
A method of manufacturing a liquid crystal display panel, wherein the alignment film of at least one substrate has been subjected to an alignment treatment so that the magnitude of the pretilt angle of the liquid crystal in the vicinity of the alignment film surface differs for each minute region, (a Coating the liquid crystal alignment film material according to the present invention on at least one of the first and second opposing substrates to form a liquid crystal alignment film;
(b) irradiating the liquid crystal alignment film with ultraviolet light through a photomask having a predetermined pattern, (c) sintering the liquid crystal alignment film, and (d) setting the surface of the liquid crystal alignment film in a certain direction. A method of manufacturing a liquid crystal display panel, comprising: a step of performing a rubbing process;

Further, in the method of manufacturing a liquid crystal display panel according to the present invention, the alignment film (31, 32) of each of the first and second substrates is formed in a minute area for each of the alignment films (31, 32) by the above-described process. After the alignment treatment is performed so that the magnitude of the pretilt angle is different, a region having a large pretilt angle near the surface of the alignment film (31) of the first substrate is formed near the surface of the alignment film (32) of the second substrate. A region facing the region having a small pretilt angle and having a small pretilt angle near the surface of the alignment film (31) of the first substrate has a large pretilt angle near the surface of the alignment film (32) of the second substrate. The method is characterized in that a step of superposing the first substrate (11) and the second substrate (12) so as to face the region is provided.

In the method of manufacturing a liquid crystal display panel of the present invention, of course, only the alignment film of one substrate (for example, the first
Of the liquid crystal (20) in the vicinity of the surface of the alignment film in each of the minute regions, and the alignment film of the other substrate (for example, the second substrate). 12 of the alignment film 32) is a liquid crystal (2) near the alignment film surface.
Orientation processing may be performed so that the pretilt angle of 0) becomes uniform. In this case, the alignment film (31) of the first substrate (11)
When the larger one of the pretilt angles near the surface is α °, the smaller one is β °, and the pretilt angle near the surface of the alignment film (32) of the second substrate (12) is γ ° In addition, it is also possible to configure so that the relationship α>γ> β is satisfied. 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. And cost reduction can be achieved.

[0046]

The principle and operation of the present invention will be described in detail below.

The liquid crystal alignment film material according to the present invention can be prepared very simply by mixing a polyimide or a polyimide precursor, a photocrosslinking agent, and a low molecular compound having a long-chain alkyl group. .

The liquid crystal alignment film material according to the present invention is dissolved in an organic solvent such as N-methyl-2-pyrrolidinone, applied to a substrate, heated and dried to form an alignment film, and has a predetermined pattern. When the alignment film surface is irradiated with ultraviolet light through a photomask, and then the liquid crystal alignment film is baked,
A region where the alignment film surface has not been irradiated with ultraviolet rays according to the pattern of the photomask exhibits a lower pretilt angle when the liquid crystal is brought into contact with the surface, as compared with a region where ultraviolet rays have been irradiated.

The mechanism by which such a phenomenon in which the pretilt angle is different occurs is not yet clearly understood, but can be presumed as follows. That is, after applying the liquid crystal alignment film material according to the present invention to a substrate to form an alignment film, the alignment film surface is irradiated with ultraviolet rays through a photomask having a predetermined pattern, and then the liquid crystal alignment film is baked. In the area where the ultraviolet light was not irradiated,
The low-molecular compound having a long-chain alkyl group evaporates because it is heated at a temperature considerably higher than its boiling point, but in the region irradiated with ultraviolet light, the low-molecular compound having a long-chain alkyl group is crosslinked by a photocrosslinking agent. Due to the reaction, it does not evaporate because it is chemically bonded to the polymer chain of the polyimide film material.

When a large number of long-chain alkyl groups are present on the substrate surface, vertical alignment is known from the literature (Frederic. J. Kahn, “O
rientation of liquid crystals by surface coupling
agents ”, Applied Physics Letters, Vol. 22, No. 8,
386, 1973). Therefore, when the long-chain alkyl group component is present on the surface of the liquid crystal alignment film, the pretilt angle of the liquid crystal molecules when the liquid crystal is brought into contact with the surface is larger than when the long-chain alkyl group component is not present. According to the above-mentioned method, by treating the distribution density of the long-chain alkyl group component on the surface of the liquid crystal alignment film to be different for each of the minute regions, the liquid crystal molecules on the surface of the alignment film for each of the minute regions can be predicted. It is considered that the pretilt angle could be made different.

In the present invention, the rubbing treatment is performed by irradiating the liquid crystal alignment film with ultraviolet rays, firing the liquid crystal alignment film,
You only have to do it once. That is, according to the present invention, simply adding an ultraviolet irradiation step to the conventional manufacturing process can provide 1
Since the effect of widening the viewing angle can be obtained by performing only one rubbing process on one substrate, it is not necessary to partially form the liquid crystal alignment film into two layers. Therefore, the manufacturing process is facilitated, and the cost can be reduced.

In the present invention, when a compound having at least two azide groups is used as a photo-crosslinking agent, the photosensitive azide group at the terminal is decomposed by light irradiation to produce a reactive nitrene, The low-molecular compound having a long-chain alkyl group can be efficiently fixed to the polymer chain of the polyimide film material, and the above-described effects can be obtained.

As such a photocrosslinking agent, in addition to 2,6-bis (4′-azidobenzal) 4-methylcyclohexanone represented by the chemical formula 1, for example,
-Diazidochalcone, 1,3-bis (4'-azidobenzal) -2-propanone shown in Chemical Formula 3, Chemical Formula 4
1,3-bis (4'-azidocinnamylidene)-
2-propanone, 4,4-diazidostilbene-2,2′-disulfonic acid represented by Chemical Formula 5, and 1,1 represented by Chemical Formula 6
3-bis (4'-azidobenzal) -2-propanone-
2; 2-disulfonic acid, 2,6-bis (4′-azidobenzal) cyclohexanone-2;
Azide groups such as disulfonic acid, 2,6-bis (4′-azidobenzal) methylcyclohexanone-2 shown in Chemical Formula 8; 2-disulfonic acid, 2,6-bis (4′-azidobenzal) cyclohexanone shown in Chemical Formula 9; Can be used. Of course, compounds having three or more azide groups can be used in the same manner.

[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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[0062]

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In the present invention, when a compound having an unsaturated bond, such as a long-chain alkyl acrylate or a long-chain alkyl methacrylate, is used as the low-molecular compound having a long-chain alkyl group, photocrosslinking occurs. The fixing of the alkyl group component by the agent can be performed very efficiently.

If the carbon number of the long-chain alkyl is too short, there is no effect of increasing the pretilt angle, the boiling point is low, and it is easy to evaporate together with the solvent. Therefore, the carbon number of the alkyl group is preferably 12 or more. . On the other hand, if the carbon number of the long-chain alkyl is too long, the compatibility with the polyimide precursor deteriorates. As a low-molecular compound having such a long-chain alkyl group,
In addition to stearyl acrylate represented by Chemical Formula 10, for example, lauryl acrylate represented by Chemical Formula 11, Chemical Formula 1
2, tridecyl acrylate represented by Chemical Formula 13, myristyl acrylate represented by Chemical Formula 13, pentadecyl acrylate represented by Chemical Formula 14, cetyl acrylate represented by Chemical Formula 15,
Heptadecyl acrylate represented by Chemical Formula 16, Chemical Formula 1
7, nonadecyl methacrylate represented by chemical formula 18, stearyl methacrylate represented by chemical formula 19, nonadecyl methacrylate represented by chemical formula 20, and the like can be used.

[0065]

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[0066]

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[0067]

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[0068]

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[0069]

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[0070]

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[0071]

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[0072]

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[0073]

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[0074]

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[0075]

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In the present invention, in order to secure a sufficient difference in pretilt angle between the photosensitive portion and the non-photosensitive portion,
It is preferable to mix the photocrosslinking agent in the same amount as the polyimide film material and the low-molecular compound having a long-chain alkyl group in a ratio of about 1/10 of the alignment film material.

The present invention is characterized in that the pretilt angle is increased by irradiating ultraviolet rays. Therefore, the base polyimide film material itself is characterized by a relatively low pretilt angle. Needless to say, it is preferable.

[0078]

Embodiments of the present invention will be described below.

[0079]

Embodiment 1 To 100 g of Nissan Chemical Industries, Ltd. polyimide varnish SE-1180 (0322), a photocrosslinking agent represented by Chemical Formula 1, that is, 2,6-bis (4′-azidobenzal) 4-methylcyclohexanone was added. 3 g (3% by weight), 0.3 g of a low-molecular compound having a long-chain alkyl group represented by the chemical formula 10, ie, stearyl acrylate
(0.3% by weight) to adjust the material of the liquid crystal alignment film.

SE-1180 (0322) is a polyimide varnish of a soluble polyimide type containing a polyimide-based polymer compound as a main component (3% by weight), and has a pretilt angle of a liquid crystal alignment film formed by a usual method. Is
About 1 degree.

FIG. 1 shows a liquid crystal display panel 100 according to one embodiment of the present invention. Note that polarizing plates (not shown) are arranged on both sides of the liquid crystal display panel 100 shown in FIG.

Referring to FIG. 1, a liquid crystal display panel 100 according to the present embodiment has liquid crystal 20 sealed between a pair of transparent substrates 11 and 12.

The pixel electrode 71 and the alignment film 31 are provided on the inner surface of the lower substrate 11. The pixel electrode 71 is connected to an active matrix circuit (not shown).

The upper substrate 12 has an ITO (Indium)
-Tin-Oxide) common electrode 72 is provided.
An alignment film 32 is provided thereon.

FIG. 2 schematically shows a method of aligning a substrate in this embodiment in order. With reference to FIG. 2, the alignment processing method in the present embodiment will be described below. Note that FIG. 2 shows only the alignment processing on the lower substrate 11 in FIG. 1, but the alignment processing is similarly performed on the upper substrate 12.

First, as shown in FIG.
Is coated with the liquid crystal alignment film material described above to form an alignment film 31.
To form

Next, as shown in FIG.
1 is irradiated with ultraviolet rays through a photomask 60 having a predetermined pattern in a nitrogen atmosphere.

Thereafter, the substrate 11 is placed in an oven for 200 minutes.
The alignment film 31 was baked by heating at 1 ° C. for 1 hour, and then rubbed in a certain direction as shown in FIG. At that time, the rubbing treatment was performed by rotating a rubbing roller 80 wound with a rayon buff cloth on the alignment film 31.

As shown in FIG. 3, the rubbing directions of the substrates 11 and 12 are substantially perpendicular to each other as shown in FIG. The rubbing directions of the substrates 12 are indicated by solid arrows), and a nematic liquid crystal 20 to which a counterclockwise chiral agent is added is inserted between the substrates.

At this time, the photosensitive portion on the surface of the alignment film 31 and the non-photosensitive portion on the surface of the alignment film 32 in the exposure process shown in FIG. The two substrates are overlapped so that the portion and the photosensitive portion on the surface of the alignment film 32 face each other.

The liquid crystal 20 is formed according to the above-described alignment treatment.
The orientation is twisted approximately 90 degrees between the substrates 11 and 12.

Further, as one goes from one substrate to the other, the pretilt direction with respect to a plane parallel to the substrate surface gradually changes, and the spray deformation is performed so that the pretilt directions near both substrate surfaces become opposite to each other. doing.
That is, the whole is in a splay type twisted nematic type alignment state.

In this liquid crystal display panel, the pretilt angles on both substrate surfaces were measured.

The result of the measurement of the pretilt angle was obtained at the photosensitive portion on the alignment film surface during the exposure treatment shown in FIG.
The degree was 1 degree in the unexposed area, indicating that the magnitude of the pretilt angle was different.

As described above, in the present embodiment, FIG.
The alignment state of the liquid crystal 20 is different for each of the small regions A and B shown in FIG. That is, in the minute area A, the lower substrate 11
The pretilt angle α near the surface of the upper substrate 12 is larger than the pretilt angle γ near the surface of the upper substrate 12, and in the minute region B, the pretilt angle γ near the surface of the upper substrate 12 is lower. It is larger than the pretilt angle β near the surface of the substrate 11.

When a voltage is applied, the minute area A,
For each B, it was confirmed that the liquid crystal rises in accordance with the larger pretilt direction of the pretilt angles α and β on the surfaces of both substrates 11 and 12.

That is, in the minute region A, the rising occurs in the pretilt direction near the surface of the lower substrate 11, and in the minute region B, it rises in the pretilt direction near the surface of the upper substrate 12.

As described above, the rising directions of the liquid crystal molecules when voltage is applied are different between the minute regions A and B, and the observer can recognize and recognize the asymmetrical viewing angle characteristics of each minute region by averaging them. Symmetrically, it is possible to perceive the display from a wider viewing angle range as compared with the above-mentioned prior art, and good viewing angle characteristics are obtained.

[0099]

Embodiment 2 FIG. 4 shows a liquid crystal display panel 100 according to a second embodiment of the present invention.
Polarizers (not shown) are arranged on both sides of the zero.

The liquid crystal display panel 100 has a liquid crystal 20 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 in FIG. The pixel electrode 71 is connected to an active matrix circuit (not shown). An ITO common electrode 72 is provided inside the upper substrate 12. The alignment film 32 is provided on the common electrode 72.

The method for aligning the first substrate 11 in this embodiment is exactly the same as the method for aligning the liquid crystal display panel of the first embodiment shown in FIG.

On the other hand, the method of aligning the second substrate (upper substrate) 12 is simpler.

That is, SE-7210 (0321) manufactured by Nissan Chemical Industries, Ltd. was applied on the substrate 12, baked in an oven at 200 ° C. for 1 hour, and then rubbed in a certain direction. SE-7210 (0321) is a liquid crystal alignment film material containing polyamic acid as a main component, and is used in a normal usage, that is, in a usage similar to that performed on the second substrate 12 according to the present embodiment. When the liquid crystal molecules are brought into contact with the alignment film surface, the pretilt angle of the liquid crystal molecules is about 6 degrees.

In this manner, the substrates subjected to the alignment treatment were overlaid in the same manner as in the first embodiment, and a nematic liquid crystal 20 to which a counterclockwise chiral agent was added 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 both substrate surfaces were measured. The measurement result of the pretilt angle was 10 degrees in the exposed portion of the alignment film surface and 1 degree in the unexposed portion during the exposure treatment shown in FIG. 2B. On the other hand, the angle of the second substrate was uniformly 6 degrees.

As described above, in the present 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 minute area A, the lower substrate 1
The pretilt angle α near the surface of the upper substrate 12
Is larger than the pretilt angle γ near the surface of the substrate 12, and in the minute area B, the pretilt angle γ near the surface of the upper substrate 12
Is larger than the pretilt angle β near the surface of the lower substrate 11.

When a voltage is applied, the minute area A,
For each B, it was confirmed that the liquid crystal rises according to the pretilt direction having the larger pretilt angle on the surfaces of both substrates 11 and 12. That is, in the minute region A, the rising occurs in accordance with the pretilt direction near the surface of the lower substrate 11, and in the minute region B, the rising occurs in accordance with the pretilt direction near the surface of the upper substrate 12.

As described above, the rising directions of the liquid crystal molecules when voltage is applied are different between the minute regions A and B, and the observer can recognize and recognize the asymmetrical viewing angle characteristics of each minute region by averaging them. Symmetrical viewing angle characteristics that allow display to be perceived from a wider viewing angle range than in the past were obtained.

[0110]

Embodiment 3 A third embodiment of the present invention is the same as the first embodiment, except that SE-1180 (0322) is used.
The liquid crystal alignment film material was adjusted by changing the mixing ratio of the photocrosslinking agent and the low-molecular compound having a long-chain alkyl group to the above. That is, 100 g of SE-1180 (0322)
To 2,6-bis (4'-azidobenzal) 4-
3 g to 1 g of methylcyclohexanone and 0.3 g to 0.1 g of stearyl acrylate were added to prepare a liquid crystal alignment film material.

A liquid crystal display panel was prepared by using the liquid crystal alignment film material of each mixing ratio in the same process as the process described in the first embodiment, and the pretilt angles on both substrate surfaces were measured. Table 1 shows the measurement results of the pretilt angle.

[0112]

[Table 1]

[0113]

Embodiment 4 3 g of a polyamic acid (chemical formula 21) synthesized from pyromellitic anhydride and 4,4′-diaminodiphenyl ether as raw materials is dissolved in 100 g of N-methyl-2-pyrrolidinone. As in 2,6
3 g (3% by weight) of -bis (4'-azidobenzal) 4-methylcyclohexanone and 0.3 g (0.3% by weight) of stearyl acrylate were added to prepare a liquid crystal alignment film material.

[0114]

Embedded image

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those described in the first embodiment, and the pretilt angles on the surfaces of both substrates 11 and 12 were measured. The measurement result of the pretilt angle was 12 degrees in the photosensitive portion on the surface of the alignment film and 2 degrees in the unexposed portion, indicating that the magnitude of the pretilt angle was different.

[0116]

Embodiment 5 3 g of a polyamic acid (chemical formula 21) synthesized from pyromellitic anhydride and 4,4′-diaminodiphenyl ether as raw materials was dissolved in 100 g of N-methyl-2-pyrrolidinone. , 3-bis (4'-azidocinnamylidene) -2-propanone
g (3% by weight), 0.3 g of stearyl acrylate
(0.3% by weight) to adjust the material of the liquid crystal alignment film.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those described in the first embodiment, and the pretilt angles on the surfaces of both substrates were measured. The measurement result of the pretilt angle was 12 degrees in the photosensitive portion on the surface of the alignment film and 2 degrees in the unexposed portion, indicating that the magnitude of the pretilt angle was different.

[0118]

Embodiment 6 3 g of a polyamic acid (chemical formula 21) synthesized from pyromellitic anhydride and 4,4'-diaminodiphenyl ether are dissolved in 100 g of N-methyl-2-pyrrolidinone. 3 g of 3,3-bis (4′-azidobenzal) -2-propanone (3 g
% By weight) and 0.3 g (0.3% by weight) of lauryl acrylate represented by Chemical Formula 11 were added to prepare liquid crystal alignment film materials.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those described in the first embodiment, and the pretilt angles on both substrate surfaces were measured.
The measurement result of the pretilt angle was 5 at the photosensitive portion on the alignment film surface.
The degree was 2 degrees in the unexposed area, indicating that the magnitude of the pretilt angle was different.

[0120]

Embodiment 7 3 g of a polyamic acid (chemical formula 21) synthesized from pyromellitic anhydride and 4,4'-diaminodiphenyl ether as raw materials is dissolved in 100 g of N-methyl-2-pyrrolidinone. 3g (3% by weight) of 3,6-bis (4'-azidobenzal) 4-methylcyclohexanone and 0.3g (0.3% by weight) of stearyl methacrylate represented by the chemical formula 18 were added to adjust the liquid crystal alignment film material. did.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those described in the first embodiment, and the pretilt angles on both substrate surfaces were measured.

The measurement result of the pretilt angle was 10 degrees at the photosensitive portion on the surface of the alignment film and 1 degree at the non-photosensitive portion, indicating that the magnitude of the pretilt angle was different.

[0123]

Embodiment 8 20 g of polyimide varnish LQ-2200 manufactured by Hitachi Chemical Co., Ltd. was diluted with N-methyl-2-pyrrolidinone to make a total amount of 100 g.
3 g (3% by weight) of 6-bis (4'-azidobenzal) 4-methylcyclohexanone and 0.3 g (0.3% by weight) of stearyl acrylate represented by the chemical formula 10 were added to prepare a liquid crystal alignment film material. . Note that LQ-2
200 is mainly composed of a polyamic acid-based polymer compound (1
5% by weight), and the pretilt angle of the liquid crystal alignment film formed by ordinary use is about 2 degrees.

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those described in the first embodiment, and the pretilt angles on both substrate surfaces were measured. The measurement result of the pretilt angle was 10 degrees at the photosensitive portion on the surface of the alignment film and 2 degrees at the unexposed portion, indicating that the magnitude of the pretilt angle was different.

[0125]

Comparative Example 1 3 g of a polyamic acid (chemical formula 21) synthesized from pyromellitic anhydride and 4,4'-diaminodiphenyl ether as raw materials was dissolved in 100 g of N-methyl-2-pyrrolidinone. , 6-bis (4 '
-Azidobenzal) 3 g of 4-methylcyclohexanone
(3% by weight) and 0.3 g (0.3% by weight) of undecyl acrylate represented by Chemical Formula 22 were added, respectively, to prepare a liquid crystal alignment film material.

[0126]

Embedded image

Using this liquid crystal alignment film material, a liquid crystal display panel was prepared by the same steps as those described in the first embodiment, and the pretilt angles on both substrate surfaces were measured. The measurement result of the pretilt angle was 3 degrees at the photosensitive portion on the alignment film surface.
Although the degree of the pretilt angle was different in the unexposed area and the pretilt angle was different, the liquid crystal alignment divided for each minute area was different from that in the first embodiment because the difference in the pretilt angle was small. Was not obtained, and the effect of widening the viewing angle was not obtained.

[0128]

Comparative Example 2 3 g of a polyamic acid (chemical formula 21) synthesized from pyromellitic anhydride and 4,4′-diaminodiphenyl ether were dissolved in 100 g of N-methyl-2-pyrrolidinone. , 6-bis (4 '
-Azidobenzal) 3 g of 4-methylcyclohexanone
(3% by weight) and 0.3 g (0.3% by weight) of eicosyl acrylate represented by Chemical Formula 23 were added, respectively, to prepare a liquid crystal alignment film material.

[0129]

Embedded image

When this liquid crystal alignment film material was applied to the substrate 11 to form a liquid crystal alignment film 31, a uniform film could not be obtained due to poor compatibility between polyamic acid and eicosyl acrylate.

[0131]

As described above, according to the present invention,
For the purpose of widening the viewing angle, a liquid crystal display panel that has been subjected to an alignment treatment so that the alignment state of the liquid crystal is different for each of the microscopic regions is changed to an ordinary process by simply adding an ultraviolet irradiation step to the alignment film. Correspondingly, it is possible to realize one substrate by one rubbing process without partially forming a two-layer structure, thereby facilitating the manufacturing process and reducing the cost. ing.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

2 (A) to 2 (C) are cross-sectional views schematically showing alignment processing of the liquid crystal display panel of FIG.

FIG. 3 is a view showing a rubbing direction of the substrate of FIG. 1;

FIG. 4 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a structure of a conventional liquid crystal display panel in which the alignment state differs for each minute region.

FIG. 6 is a cross-sectional view showing another structure of a conventional liquid crystal display panel in which the alignment state differs for each minute region.

FIGS. 7A to 7E are cross-sectional views schematically illustrating an alignment process of the liquid crystal display panel of FIG. 6 in order.

FIG. 8 is a cross-sectional view showing another structure of a conventional liquid crystal display panel in which the alignment state differs for each minute region.

[Explanation of symbols]

 11, 12 Substrate 20 Liquid crystal 31, 32 Alignment film 40 Resist material 51 First alignment film layer 52 Second alignment film layer 60 Photomask 71 Pixel electrode 72 Common electrode 80 Rubbing roller 100 Liquid crystal display panel

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1337

Claims (7)

(57) [Claims] A first and a second substrate provided with an alignment film and facing each other, and a nematic liquid crystal in a splay type twisted nematic type alignment state inserted between the first and second substrates. Wherein the alignment film of at least one of the first and second substrates has an alignment treatment such that the magnitude of the pretilt angle of the liquid crystal in the vicinity of the alignment film surface is different for each minute region. A method for manufacturing a liquid crystal display panel, comprising: (a) having at least one of the first and second substrates, a polyimide or a polyimide precursor, a photocrosslinking agent, and a long-chain alkyl group. the via and forming a liquid crystal alignment film by applying a low molecular compound, a mixture comprising at liquid crystal alignment film material, a photomask having a pattern of a plurality of micro-regions (b) the liquid crystal alignment film Liquid crystal alignment film Multiple micro territories on
Area is irradiated with ultraviolet light, and the liquid crystal alignment film is irradiated with ultraviolet light.
The plurality of micro regions and the other plurality not irradiated with ultraviolet rays
A step of forming a minute domains, a step of firing (c) said liquid crystal alignment film, (d) a step of the alignment film surface is rubbed in a predetermined direction, comprising the, the small alignment regions A method for manufacturing a liquid crystal display panel, comprising a forming step. 2. The liquid crystal alignment film material, wherein the polyimide precursor is a polyamic acid.
2. The method for manufacturing a liquid crystal display panel according to 1 . 3. The liquid crystal alignment film material, wherein the photo-crosslinking agent is
The process according to claim 1 or a liquid crystal display panel of claim 2, wherein the a compound having at least two azido groups. Wherein said liquid crystal alignment film material, a low molecular compound having a long chain alkyl group, according to any one of claims 1 to 3, characterized in that a compound having an unsaturated bond Of manufacturing a liquid crystal display panel. According to claim 5, wherein the liquid crystal alignment film material, the length low molecular weight compound having an alkyl group, as claimed in claims 1 to 4 any one of, wherein the long chain alkyl acrylate A method for manufacturing a liquid crystal display panel. 6. The method for manufacturing a liquid crystal display panel according to claim 5 , wherein the number of carbon atoms of the long-chain alkyl group in the liquid crystal alignment film material is 12 or more and 19 or less. 7. The alignment film of the first and second substrates is subjected to an alignment process so that the magnitude of the pretilt angle of the liquid crystal in the vicinity of the alignment film surface differs for each minute region. A region having a large pretilt angle near the surface of the alignment film on the substrate is opposed to a region having a small pretilt angle near the surface of the alignment film on the second substrate, and the surface of the alignment film on the first substrate is formed. Superimposing the first substrate and the second substrate such that a region having a small pretilt angle in the vicinity faces a region having a large pretilt angle in the vicinity of the surface of the alignment film of the second substrate. the method for manufacturing a liquid crystal display panel according to claim 1, further comprising.