JP2001242465A - Method for manufacturing liquid crystal alignment layer, light irradiation device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid crystal alignment layer, using an optical alignment technology wherein light irradiation with high light utilizing efficiency is realized, even when using a light source having a wavelength distribution and the like, and a plurality of irradiated regions can be controlled with high precision and superior uniformity and dividability of alignment and easy operations are attained. SOLUTION: An alignment layer 12, in which an isotropic liquid crystal alignment capability is generated by light irradiation, is manufactured on a substrate 11. Light 31 from a light source is refracted, by making the light pass through a light refraction element 21 to convert it into light 32 going into another direction, and the alignment layer 12 is irrandiated with light 32. The use of the light refracting element 21 enables easy change of the light incidence angle on the substrate 11, by changing only the position of the light refraction element 21, while the positions of the light source and the substrate 11 remain fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a liquid crystal alignment film for imparting liquid crystal alignment ability by light irradiation, a light irradiation device used in this method, and a liquid crystal alignment film produced by this method. The present invention relates to a liquid crystal display device used.

[0002]

2. Description of the Related Art In a liquid crystal display device, an alignment film for aligning liquid crystal molecules in one direction at a substrate interface is provided between a substrate and a liquid crystal layer. A method of manufacturing a liquid crystal alignment film that is widely used at present is a rubbing method in which a thin film of a polymer such as polyimide is formed on a substrate, and the surface of the thin film is mechanically rubbed with a rayon cloth, a nylon cloth, or the like. However, the rubbing method is a technique of mechanically rubbing the surface of a polymer,
A part of the alignment film or the rubbing cloth is peeled off, resulting in minute dust. Therefore, the manufacturing environment is polluted by these minute dusts, and a washing and drying process for removing the dusts is indispensable. In the rubbing method,
TF is generated by generating static electricity when rubbing the alignment film.
There are also problems such as that active elements such as T are destroyed and that it is difficult to uniformly orient evenly on a large substrate.

As a method for overcoming such a disadvantage of the rubbing method, a method for producing a non-contact type liquid crystal alignment film using light is known. For example, a method using an anisotropic absorbing molecule such as an azo dye disclosed in Nature 351, P.49 [1991] or Japanese Patent Application Laid-Open No. 2-277025, and using a polyimide disclosed in Proc. IDRC 94 P.213. Method, Jpn. J. Appl. Phys., 31, P.
A method using a polymer having a photoreactive group in a side chain such as polyvinyl cinnamate disclosed in 2155 [1992] and JP-A-5-232473 is known.

On the other hand, a liquid crystal alignment film generally requires a pretilt angle. In a TN (twisted nematic) type or STN (super twisted nematic) type liquid crystal display device, a pretilt angle of about 1 ° to 10 ° is required in order to prevent occurrence of reverse tilt. In addition, the vertical alignment film needs to be slightly tilted, that is, the pretilt angle is slightly smaller than 90 °, in order to avoid random orientation of the liquid crystal molecules when a voltage is applied. In the horizontal orientation rubbing method, pretilt generally occurs at the same time as rubbing, but there is a problem inherent in the above rubbing method. On the other hand, by rubbing the vertical alignment film,
It is known that a pretilt angle can be provided in one direction, but it is difficult to obtain a uniform pretilt angle by the rubbing method.

In the method of manufacturing a liquid crystal alignment film using light, a pretilt can be applied by irradiating the alignment film with light in an oblique direction. For example, Japanese Patent Application Laid-Open No. 8-304828 discloses a method of imparting a pretilt to a horizontal alignment film by irradiating twice. Japanese Patent Application Laid-Open No. 9-211468 discloses a method of imparting a pretilt by irradiating a vertical alignment film with light obliquely.

Further, from the viewpoint of improving the viewing angle, there is known a pixel division type liquid crystal display device in which the alignment state of liquid crystal molecules in each pixel is changed. As a method of irradiating light by dividing as described above, a method of irradiating light by using a mask is disclosed in JP-A-8-30.
No. 4828 and Japanese Patent Application Laid-Open No. 9-211468 (hereinafter, referred to as "first prior art"). As a method of irradiating light at one time, a method of irradiating light from a plurality of directions through a holographic diffraction grating is disclosed in Japanese Unexamined Patent Publication (Kokai) No. Heisei 9 (1999).
It is disclosed in Japanese Patent Application Laid-Open No. 10-123521 (hereinafter, referred to as "second conventional technique").

FIG. 5 is an explanatory diagram showing the first conventional technique. Hereinafter, description will be made based on this drawing.

First, an alignment film 12 on which anisotropic liquid crystal alignment ability is generated by light irradiation is formed on a substrate 11. Subsequently, the light 31 from the light source is passed through the mask 22 at an angle. Thereby, the alignment film 12 is irradiated with the light 32 that has passed through the light transmitting portion 22 a of the mask 22. At this time, the light shielding portion 22b of the mask
As a result, a portion where the alignment film 12 is not irradiated with light is generated. Subsequently, this portion is irradiated with light 32 using light 31 from another light source inclined in reverse and another mask 22.

FIG. 6 is an explanatory view showing a second conventional technique. Hereinafter, description will be made based on this drawing.

First, an alignment film 12 on which anisotropic liquid crystal alignment ability is generated by light irradiation is formed on a substrate 11. Subsequently, the light 31 from the light source is inclined and passed through the holographic diffraction grating 23. Thereby, the holographic diffraction grating 23
The light 32a passing through the light transmitting part 23a and the light 32b passing through the refraction part 23b of the holographic diffraction grating 23 are irradiated on the alignment film 12 at different angles.

[0011]

However, the first prior art has the following problems.

Since half or more of the illuminating light is shielded by the light-shielding portion of the mask, there is a problem that the light use efficiency is significantly reduced to 以下 or less. Further, since a plurality of irradiations using different masks are required, a plurality of masks and a plurality of mask alignment steps are required. Furthermore, since light irradiation from different directions is necessary, it is necessary to perform irradiation using a plurality of light sources, or to perform light irradiation a plurality of times by changing the position of the light source or the inclination or direction of the substrate. For this reason, there are problems such as an increase in the complexity of the apparatus, a decrease in productivity and an increase in cost accompanying the apparatus.

On the other hand, the second prior art has the following problems.

A holographic diffraction grating is an element based on the principle of wave optics, and is designed to function for a specific wavelength incident thereon. However, the light source used for light irradiation is better than a single wavelength light source such as laser light.
Light sources that cover a wide wavelength range, such as high-pressure mercury lamps and xenon lamps, are common. Therefore, when light from a light source having such a wavelength distribution is irradiated through a diffraction grating, the diffraction angle varies depending on the wavelength, and it is difficult to selectively irradiate a predetermined area. Therefore, especially when the irradiation from different directions is mixed at the boundary between the regions having different light irradiation angles, the boundary becomes unclear,
There are problems such as uneven irradiation intensity. To avoid these problems, light from a light source having a wavelength distribution can be passed through a diffraction grating by narrowing the wavelength range by passing the light through a band-pass filter or the like.
In this case, light other than a specific wavelength is cut by the bandpass filter, so that the light use efficiency is significantly reduced.

In a transmission type holographic diffraction grating or the like, light is generally transmitted in response to irradiation from the front, that is, zero-order diffracted light is generated. It is difficult to convert the light into irradiation light. A phase grating having a rectangular cross section can be designed so that transmitted light in the front direction, which is the 0th-order diffracted light, is zero. However, in order to accurately reduce the transmitted light in the front direction to zero, it is necessary to control the depth of the rectangular shape with high accuracy in the order of wavelength. Further, the intensity of the 0th-order diffracted light is 0
Again, only for specific wavelengths. Therefore, when a light source having a wavelength distribution is used, transmitted light, that is, 0th-order diffracted light cannot be reduced to zero.

Even when a single-wavelength light source such as a laser beam is used, in a transmission type diffraction grating, high-order diffracted light is generally generated simultaneously in accordance with the expression of the diffraction grating (see FIG. 7). ). Then, the incident light is diffracted by the plurality of diffracted lights in a direction different from the intended direction, and is irradiated on the alignment film. As described above, it is extremely difficult to control the direction of irradiation of the alignment film with light, including high-order diffracted light. On the other hand, it is also possible to design a diffraction grating so that a plurality of diffracted lights do not occur. However, since the degree of freedom in designing the diffraction grating is significantly reduced,
Designing a diffraction grating that irradiates light in any direction and area is also extremely difficult. As described above, even when a single-wavelength light source is used, it is difficult to irradiate the alignment film with light only from a desired direction and to provide a highly accurate divided alignment structure even when a single-wavelength light source is used.

Further, the pixel size in the liquid crystal display device is on the order of 100 μm to 10 μm.
It is difficult to fabricate holographic diffraction gratings of this size and having different structures on the same substrate. Further, even if a diffraction grating of such a size is manufactured, it is difficult to perform advanced control of a boundary portion in the divided structure because light of different diffraction grating regions causes disturbance of diffracted light due to interference. .

[0018]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a liquid crystal alignment film using an optical alignment technique which has no problem such as generation of minute dust in a rubbing method and generation of static electricity due to friction. Even when a light source or the like is used, it is possible to irradiate light with high light use efficiency, and it is possible to control a plurality of irradiation areas with high accuracy, and it is excellent in uniformity and division of orientation and easy to operate. An object of the present invention is to provide a method for manufacturing a liquid crystal alignment film.

[0019]

According to a method of manufacturing a liquid crystal alignment film according to the present invention, an alignment film in which anisotropic liquid crystal alignment ability is generated by light irradiation is formed on a substrate, and a light refraction for refracting light is performed. Light from a light source is applied to the alignment film through the element.

The light refracting element may be one that refracts light in a plurality of directions, one that forms a plurality of (for example, two) regions with different light irradiation directions for one pixel of the alignment film, a triangular prism, It may be a pyramid, a curved surface, a portion having a different refractive index, or the like.

Polarized light may be used as light to be applied to the alignment film, and light may be incident on the inclined surface of the photorefractive element so as to be p-polarized light. A polarization plane changing element that changes the plane may be used. Further, the alignment film may be a vertical alignment film, a horizontal alignment film, or the like.

The light irradiation device according to the present invention is used in the method of manufacturing a liquid crystal alignment film according to the present invention, and includes a light source and a light refracting element for refracting light. The light source and the light refraction element are arranged so that the light from the light source is refracted through the light refraction element and then applied to the liquid crystal alignment film. In addition, a light source and a polarization plane changing element are added so that a light from the light source is refracted through the polarization plane changing element and the light refraction element, and then irradiates the liquid crystal alignment film by adding a polarization plane changing element for changing the polarization plane. And a light refracting element.

In the liquid crystal display device according to the present invention, a liquid crystal layer is provided between two substrates, and an interface between at least one of the two substrates and the liquid crystal layer is formed by the method for manufacturing a liquid crystal alignment film according to the present invention. The manufactured alignment film is provided.

[0024]

FIG. 1 is an explanatory view showing a first embodiment of a method for producing a liquid crystal alignment film according to the present invention. Hereinafter, description will be made based on this drawing.

An alignment film 12 on which anisotropic liquid crystal alignment ability is generated by light irradiation is formed on a substrate 11. Subsequently, the light 31 from the light source is refracted by being transmitted through the light refraction element 21, converted into light 32 traveling in different directions, and irradiated to the alignment film 12. In FIG. 1, the vertically incident light is converted into light in an oblique direction. However, it is also possible to convert incident light from an oblique direction into light in a vertical direction.

By using such a light refracting element 21 that refracts light and changes the traveling direction of the light, the position of the light refracting element 21 is fixed while the position of the light source (not shown) and the substrate 11 is fixed. By changing only the incident angle, the incident angle of light on the substrate 11 can be easily changed.

FIG. 2 is an explanatory view showing a second embodiment of the method for producing a liquid crystal alignment film of the present invention. Hereinafter, description will be made based on this drawing. However, the same parts as those in FIG.

A half-wave plate 41 serving as a polarization plane changing element for changing the polarization plane is provided between a polarization element (not shown) and the light refraction element 21 such as a prism. Light 33 from the light source is polarized by the polarizing element. Thus, as shown in FIGS. 2A and 2B, only the half-wave plate 41 and the photorefractive element 21 are moved and rotated while the position of the light source (not shown) and the substrate 11 are fixed. By doing so, it is possible to change the plane of polarization and the irradiation angle on the alignment film 12 (see irradiation light 34a, 34b).

FIG. 3 is an explanatory view showing a third embodiment of the method for producing a liquid crystal alignment film of the present invention. Hereinafter, description will be made based on this drawing. However, the same parts as those in FIG.

The light refracting element 21a converts the light 31 from the light source into a plurality of lights 32a to 32d having different traveling directions.
Therefore, the alignment films 12 are irradiated with the light beams 32a to 32d in such a manner as to be divided into a plurality of regions having different irradiation directions.
By setting the size of the slope of the photorefractive element 21a to half the pixel size, the alignment film 12 in which one pixel is divided into two regions can be obtained. When the light refracting element 21a is a pyramid-shaped quadrangular pyramid, the alignment film 12 obtained by dividing one pixel into four is obtained.

Next, the configuration and operation of the method for producing a liquid crystal alignment film of the present invention will be described in more detail.

1. In the method for manufacturing a liquid crystal alignment film of the present invention as described above, since there is no light-shielding portion unlike the method using a mask, most of the incident light reaches the alignment film, so that the light use efficiency is high. In addition, since a plurality of irradiations using different masks are unnecessary, a plurality of masks and a plurality of mask alignment steps are not required. Further, there is no need for a step of sequentially irradiating light from different directions using a plurality of light irradiations or a plurality of light sources, and a step of changing the irradiation direction by changing the position of the light source or the inclination of the substrate, thereby increasing the apparatus cost. rare. Furthermore, there are no problems such as an increase in the number of steps and a positional shift between the aligned mask and the substrate in these steps.

2. In the method for producing a liquid crystal alignment film of the present invention,
After an alignment film in which anisotropic liquid crystal alignment ability is generated by light irradiation is formed on a substrate, light from a light source is irradiated to the alignment film through a photorefractive element. Since the refraction phenomenon generally follows Snell's law (n1 · sin θ1 = n2 · sin θ2),
The wavelength dependence of the refraction angle of the incident light is determined by the refractive indices n1,
It only affects indirectly through n2. Therefore, since there is no large wavelength dependency unlike a holographic diffraction grating based on the principle of wave optics, the chromatic dispersion in the traveling direction of light is smaller than that of the conventional method. Therefore, even when using a light source having a wide wavelength distribution such as a high-pressure mercury lamp widely used for light irradiation, a xenon lamp, or the like, the light irradiation angle is different, and it is difficult to selectively irradiate a predetermined region.
There is no problem such as inconsistency of the mixed portion at the boundary between regions having different irradiation angles, which makes the boundary unclear or uneven irradiation intensity.

3. Since the chromatic dispersion is small and can be used for a wide range of wavelength distribution, it is not necessary to narrow the wavelength range by passing a light from a light source having a wide wavelength distribution through a band-pass filter, etc. It does not drop. Further, by using a material having a small wavelength dependence of the refractive index, the wavelength dependence can be reduced. Further, by using a photorefractive element having more appropriate wavelength dependency, chromatic dispersion can be completely suppressed.

4. In the method for producing a liquid crystal alignment film of the present invention,
Since there is no generation of higher-order diffracted light as in the case of using a diffraction grating, light is not diffracted in a direction different from the intended direction. Thereby, a desirable division structure is obtained, and there is no difficulty in controlling the design of the diffraction grating. Since a diffraction grating generates higher-order diffracted light, it is difficult to determine the direction of irradiation on the alignment film.

5. In FIG. 3, by irradiating light with the tip of the prism-shaped light refracting element sufficiently close to the alignment film, it is possible to completely eliminate mixing of light from an adjacent region. Further, by setting the vertex of the prism to be at the center of the pixel electrode, an effect of collecting light at the pixel portion can be obtained. Furthermore, there is an advantage that alignment is easy by matching the vertex of the prism or the most engraved portion to the electrode of the pixel.

6. In the method for producing a liquid crystal alignment film of the present invention,
There is no problem of generation of transmitted light in the front direction, which is a problem in transmission type diffraction gratings, and no high-precision processing technology such as controlling the depth of a rectangular shape in a wavelength order as seen in a phase grating is required. .

7. The shape of the photorefractive element has a pixel size of 1
Even in the case of the order of 00 μm to 10 μm, the production is easy because only one or a pair of slopes need to be produced at this size. In addition, since light in different diffraction grating regions causes interference and diffracted light is disturbed, there is no problem that it is difficult to control the boundary of the divided structure.

8. In the method for producing a liquid crystal alignment film of the present invention, polarized light can be used as the irradiation light.
The light transmittance and reflectance at the interface are given by the Fresnel equation. Therefore, when using polarized light,
The light is transmitted most effectively when the polarized light incident on the inclined surface of the photorefractive element or the polarized light emitted from the inclined surface is p-polarized light.

9. The “light” used in the present invention refers to an electromagnetic wave for generating anisotropic alignment ability in an alignment film, and includes infrared rays and X-rays in addition to visible light and ultraviolet light. In particular, the light that causes a reaction or the like in the alignment film is preferably ultraviolet light, and more preferably light in a wavelength region that is absorbed by the alignment film. KrF, Ar as a light source for generating such light
An ultraviolet laser light source such as F, a visible light laser light source, an infrared laser light source, or light obtained by wavelength-converting light from these light sources using a nonlinear element or the like can be used. In the method for producing a liquid crystal alignment film of the present invention, in addition to the single-wavelength light source as described above, a light source having a wavelength distribution such as a mercury lamp, a xenon lamp, or the like having an ultra-high pressure, a high pressure, or a low pressure, an excimer having a relatively narrow wavelength range. A UV lamp such as a lamp can be used without any problem.

10. The light irradiation may be irradiation in an oblique direction, irradiation twice or more, simultaneous irradiation from two or more light sources, or the like, in addition to irradiation in the vertical direction to the substrate. In particular, irradiation of the alignment film from an oblique direction or irradiation twice is effective for generating pretilt.

11. “Light” used in the present invention may be polarized light. Polarized light includes partial polarized light in addition to linearly polarized light. In addition, even in the case of non-polarized light such as natural light, by irradiating the light refraction element from an oblique direction, the intensity of polarized light components in two orthogonal directions will be different. It will have the same effect. Therefore, such light is also included.

12. The polarized light is a laminated type in which light from an unpolarized light source is arranged at a Brewster angle with respect to the incident angle of the polarizing film, the polarizing prism, and the laminated quartz substrate, in addition to the already polarized light such as a laser light source. It can be obtained by transmitting a polarizing plate or the like.

13. The photorefractive element needs to have a property of transmitting predetermined light. The higher the transmittance, the better, but it can be used as long as light is transmitted. As such a light refracting element, quartz,
An inorganic material such as glass, an organic material such as a polymer material, or the like can be used. In particular, when using short-wavelength light such as ultraviolet light, a material such as quartz that does not absorb light up to the short-wavelength region,
It is desirable to use a polymer material that absorbs relatively little in the short wavelength region. From the viewpoint of ease of processing and the like, an organic material such as a polymer material is desirable.

14. “Refraction” refers to changing the traveling direction of light when passing through a different medium (substance). It may have a clear interface, or may have a medium in which the refractive index changes continuously to continuously change the traveling direction of light. In the case of refraction at the interface,
The interface may be flat or curved. Examples of the flat surface include a prism-shaped one, a pyramid-shaped one, one in which these are continuously repeated, and one in which these shapes are formed on the substrate surface. Examples of the curved surface include a concave or convex curved lens or Fresnel lens, a lens in which these are continuously repeated, and a lens in which these shapes are formed on a substrate surface. In these materials, the light incident on the photorefractive element can be irradiated in a plurality of directions, or can be divided into two, four, or more directions.

15. In the method of manufacturing a liquid crystal alignment film of the present invention, the region corresponding to each pixel may be processed into a single region, but each pixel is divided into a plurality of regions having different alignment directions. It may be a split type. Examples of such a pixel division type include two divisions and four divisions. Further, each of the upper and lower substrates may be divided into two parts, and these may be combined into four parts.

16. In the photorefractive element shown in FIG.
FIG. 4 shows the relationship between the apex angle on the lower side of the prism structure and the irradiation angle on the alignment film obtained by calculation. Here, the refractive indices of the light refraction element and air were 1.5 and 1.0, respectively.
From this figure, it can be seen that the angle of incidence on the alignment film can be controlled from 0 ° to 40 ° by controlling the vertex angle of the prism from 180 ° to 100 °.

17. When a light refracting element having a prism shape as shown in FIG. 3 is used, there is also an effect that incident light is condensed at the center, and there is also an advantage that irradiation intensity is improved. Usually, in a liquid crystal display device, an opaque wiring or the like is provided on a part of a substrate, and since this part does not contribute to display, alignment is unnecessary. Therefore, by setting the apex angle portion of the prism shape in FIG. 3 at the center of the pixel, light that would otherwise hit the wiring portion around the pixel is focused on the pixel portion. Accordingly, there is an effect that the light use efficiency is improved and a two- or four-part alignment structure can be obtained.

18. Even when a light refracting element having a curved surface such as a lens is used, an effect of bending light in a predetermined direction and an effect of condensing light to increase light use efficiency can be obtained. In addition, by appropriately controlling the refraction direction and the light collecting effect of light using a curved surface, the alignment effect can be partially changed. Such high-precision control suppresses the influence of horizontal electrolysis from wiring other than the pixels, and is thus effective in preventing the occurrence of discrimination.

19. As long as the light refracting element is uniformly oriented over a wide range, an ordinary or large prism or the like having a plane or a curved surface with a size of several cm to several tens cm can be used. On the other hand, when performing a divisional orientation or the like in a pixel size, it is necessary to produce a shape in the same pixel size. Examples of the manufacturing method include cutting using diamond or the like, injection processing such as microblasting and sandblasting, processing using laser or ultrasonic waves, processing using etching, and the like. Furthermore, it is also possible to prepare a prototype by the above method, and copy and use this by another method such as a polymer material. Note that the unevenness of the light refracting element used in the present invention has a pixel size even when pixel division is performed, and is therefore much larger than the unevenness of the diffraction grating, which facilitates fabrication.

20. As the polarization plane changing element, for example, 1
/ 2 wavelength plate. For example, by installing a half-wave plate as shown in FIG. 2 between a polarizing element and a light refracting element such as a prism, by rotating only the half-wave plate and the polarizing element, etc. The irradiation angle can be changed.

21. The “alignment film that generates anisotropic liquid crystal alignment ability by light irradiation” in the present invention includes, but is not limited to, an alignment film generally called a photo-alignment film. Even when a normal alignment film is used, some liquid crystal alignment ability is generated by light irradiation, and one in which the substrate itself has liquid crystal alignment ability. Of the alignment film.

22. The alignment film in which anisotropic liquid crystal alignment ability is generated by light irradiation includes both a horizontal alignment film and a vertical alignment film. In the horizontal alignment film, the pretilt is generated by the oblique irradiation, so that the rising direction of the liquid crystal molecules is controlled. In the vertical alignment film, pretilt is attached so that it falls slightly in either direction,
The direction in which liquid crystal molecules fall when voltage is applied is limited.

23. As described above, the present invention has been described as a method for manufacturing a liquid crystal alignment film, but these contents can be regarded as a light irradiation device as it is. Therefore, the present application also discloses such a light irradiation device.

24. Examples of the vertical alignment film used in the present invention include a polyimide alignment film having a side chain such as a long alkyl chain, other polymer alignment films, and a silane coupling agent. Even if it does not have an optically reactive functional group or the like, most of the vertical alignment films have a pretilt anisotropy due to light irradiation from an oblique direction. Can be used.

25. As the horizontal alignment film used in the present invention, an alignment film using an anisotropic absorbing molecule such as an azo dye (JP-A-2-77025), a film using a molecule having photoisomerization characteristics such as azobenzene, An alignment film (such as PROC. IDRC 94 P.213) that irradiates polyimide with ultraviolet light or other light to make use of decomposition and photoreaction, etc., and photoreactive groups such as polyvinyl cinnamate and chalcone monomers Any of polymers having a chain (JP-A-5-232473, etc.) and polymers such as polyester, polyamide, polyurethane, polyetherimide (IDW'99 P.21 [1999], IDW'99 P.85 [1999]) Can also be used.

26. Various liquid crystals such as a nematic liquid crystal, a smectic liquid crystal, and a bistable liquid crystal can be aligned using the liquid crystal alignment film manufactured in the present invention, and a liquid crystal display device can be manufactured using these liquid crystals. In this case, the alignment film according to the manufacturing method of the present invention may be used on one of the substrates or on both.

27. The liquid crystal may contain an additive such as a chiral agent, or may contain a polymer solid such as a polymer-dispersed liquid crystal or a polymer network. Such a polymer network can also be produced by a method in which a photocurable monomer, a thermosetting monomer, an oligomer thereof, or the like is dissolved in a liquid crystal material, injected between substrates, and then reacted.

28. The liquid crystal display device using the organic thin film of the present invention as a liquid crystal alignment film is not limited to a TN type, but can be used for any of an STN type, an in-plane switching (IPS) type, a ferroelectric liquid crystal, and the like. In these liquid crystal display devices, a method of applying a voltage to the electrodes of both substrates may be a static drive for applying a constant voltage or a dynamic drive for applying a changing voltage. The dynamic drive may be a simple matrix or an active matrix such as a TFT or MIM. Further, the liquid crystal display device of the present invention is not limited to a transmission type, but may be a reflection type or the like. In this case, one of the substrates does not need to be transparent, and when the substrate is opaque, when the substrate is a mirror surface or other reflective surface, or when the substrate also serves as an electrode, the liquid crystal display of the present invention can be used. Included in the device.

[0060]

Next, the method for producing a liquid crystal alignment film of the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following embodiments, and various modifications or changes can be made without departing from the spirit of the present invention.

Example 1 First, a solution of polyvinyl cinnamate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) in methylcellosolve acetate (concentration: 4 wt%) was added to ITO (indium tin oxide).
Glass substrate (25 mm) with transparent electrode (10 mm width)
X 35 mm) by spin coating (rotational speed 200
0 rpm), heated at 100 ° C for 1 hour, thin film (alignment film)
I got Next, use a UV light source (Ushio SPOTCURE VIS2510
0: high-pressure mercury) was polarized through a laminated polarizer in which 20 pieces of quartz glass were laminated at a polarization angle, and then irradiated for 4 minutes from the direction perpendicular to the substrate. The irradiation amount is 254 nm
It was 1.0 J / cm ² in conversion. Subsequently, the substrate is
(4) The film was rotated and polarized light similarly obtained from the same light source was irradiated onto the thin film on the substrate for 2 minutes through a photorefractive element (prism) as shown in FIG. The cross section of the prism is a right-angled isosceles triangle, and the angle of the slope is 45 °. The light passing through the photorefractive element was applied to the thin film on the substrate in an oblique direction, and the irradiated light was p-polarized with respect to the plane of the substrate.

Subsequently, a sealant was applied to the periphery of the substrate together with another substrate produced in the same manner as described above. Subsequently, the pretilt was adjusted so as to match the twisting direction of the right-handed liquid crystal, and these substrates were bonded together while applying pressure so that the orientation directions of both substrates were 90 °. The cell gap is 5 μm using latex spheres as a spacer.
Was adjusted to Subsequently, the produced empty cell was placed in a vacuum chamber, and after evacuation, a liquid crystal material was injected. The liquid crystal is nematic liquid crystal (ZLI4792: Merck) and chiral material S81
The one to which 1 was added was used. After the injection of the liquid crystal material was completed, the injection port was sealed.

When the manufactured liquid crystal cell was observed by crossed Nicols with a polarizing microscope, it was found to be a TN type liquid crystal cell. When a voltage was applied to the manufactured liquid crystal cell, the liquid crystal molecules were observed to rise from one direction, and no discrimination was observed. Further, two substrates irradiated with light in the same manner as described above were bonded so that the rubbing directions were reversed, and a liquid crystal containing no chiral agent was injected to form a cell. The pretilt angle was measured using the crystal rotation method (using Central Seiki OMS). The pretilt angle was 3.0 °.

Comparative Example 1 A cell was manufactured in the same manner as in Example 1 except that the second irradiation from a diagonal direction using a prism was not performed. When a voltage was applied, the liquid crystal molecules started to rise in two directions, white discrimination occurred at the boundary, and good contrast could not be obtained. When the pretilt angle was measured by the same method as in Example 1, the pretilt angle was 0.1%.
Was ゜.

Example 2 A thin film was formed on a substrate in the same manner as in Example 1. Then, a UV light source (Ushio SPOTCURE VI
UV light from S25100: high pressure mercury) was polarized through a laminate polarizer, and then irradiated through a half-wave plate for 4 minutes from the direction perpendicular to the substrate. Subsequently, the thin film on the substrate was irradiated with polarized light similarly obtained from the same light source through a half-wave plate and a prism for 2 minutes as shown in FIG. The half-wave plate has been rotated by 45 ° since the first irradiation, and the polarization plane is 1
The film was irradiated as p-polarized light at 90 ° different from the first irradiation. In this embodiment, only by moving the prism and the half-wave plate, etc., two irradiations, vertical irradiation and oblique irradiation, are possible with the state of the substrate and the light source fixed.

A cell into which liquid crystal was injected was manufactured in the same manner as in Example 1. Observation of the produced liquid crystal cell by crossed Nicols with a polarizing microscope revealed a TN liquid crystal cell.
When a voltage was applied to the manufactured liquid crystal cell, the liquid crystal molecules were observed to rise from one direction, and no discrimination was observed.

Example 3 A solution of polyvinyl cinnamate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) in methylcellosolve acetate (concentration: 4 wt%) was prepared using an ITO (indium tin oxide) transparent electrode (10 mm width) with an alignment marker. Spin coating method on glass substrate (2000 rpm)
m) and heating at 100 ° C. for 1 hour to obtain a thin film. Subsequently, after UV light from a UV light source (Ushio SPOTCURE VIS25100) was polarized through a laminated plate polarizer, irradiation was performed for 4 minutes from a direction perpendicular to the substrate. Subsequently, the substrate was rotated by 90 °, and the polarized light similarly obtained from the same light source was irradiated on the thin film on the substrate for 2 minutes through a prism sheet-like light refracting element as shown in FIG. The prism sheet-shaped light refracting element is obtained by digging a large number of grooves in one direction on a surface of a quartz substrate by cutting using diamond. The cross section of the groove is an isosceles triangle as shown in FIG.
The repetition period of the groove is 400 μm. Light was irradiated in a state where the prism sheet-shaped light refracting element was almost in contact with the substrate. The light transmitted through the photorefractive element was applied to the substrate as p-polarized light from two oblique directions.

A sealant was applied to the periphery of the substrate together with another substrate produced in the same manner as described above, and they were bonded together while applying pressure so that the orientation directions of both substrates were 90 °. The cell gap was adjusted to 5 μm using a latex sphere as a spacer. The produced empty cell was placed in a vacuum chamber, and after evacuation, a liquid crystal material was injected. In the liquid crystal,
Nematic liquid crystal (ZLI4792: manufactured by Merck) was used. No chiral material was added. After the injection of the liquid crystal material was completed, the injection port was sealed.

When the fabricated liquid crystal cell was observed by crossed Nicols with a polarizing microscope, it was found to be a split-type TN type liquid crystal cell. Observation while applying a voltage to the produced liquid crystal cell revealed that the liquid crystal cell was formed into a four-divided liquid crystal layer having a different liquid crystal twist direction and a rising direction corresponding to the occurrence of a predetermined pretilt at a period of 200 μm.

Example 4 A polyimide solution for vertical alignment (JALS-682: manufactured by JSR) was spin-coated on a glass substrate having an alignment marker having a transparent electrode (10 mm width) of ITO (indium tin oxide). Apply (30 rotations)
00 rpm), heating at 90 ° C. for 10 minutes, and then heating at 200 ° C. for 60 minutes.
By calcining for a minute, a polyimide thin film (alignment film) was obtained. continue,
A UV light from a UV light source (Ushio SPOTCURE VIS25100) was irradiated with a non-polarized light through a prism sheet-like photorefractive element similar to that in Example 3 to the thin film on the substrate for 20 minutes. The irradiation amount was 4.0 J / cm ² in terms of 254 nm.
By irradiating the light with the prism sheet-shaped light refracting element approaching a state almost in contact with the substrate, the light transmitted through the light refracting element was irradiated on the substrate as p-polarized light from two oblique directions.

A sealant is applied to the periphery of the substrate together with another substrate produced in the same manner as above, and both substrates are aligned while pretilt directions of both substrates are the same (shifted by 200 μm). These were bonded together under pressure. The cell gap was adjusted to 5 μm using a latex sphere as a spacer. The produced empty cell was placed in a vacuum chamber, and after evacuation, a liquid crystal material was injected. In the liquid crystal,
Nematic liquid crystal with negative dielectric anisotropy (MLC660
8: Merck). After the injection of the liquid crystal material was completed, the injection port was sealed.

When the fabricated liquid crystal cell was observed by crossed Nicols with a polarizing microscope, it was found to be a vertically aligned liquid crystal cell. When the prepared liquid crystal cell was observed while applying a voltage, it was observed that the liquid crystal cell fell in two directions at a period of 200 μm.

(Example 5) A liquid crystal cell was manufactured in the same manner as in Example 4, except that the two substrates were bonded with the directions shifted by 90 °. When the produced liquid crystal cell was observed by crossed Nicols with a polarizing microscope, the liquid crystal cell was found to be a vertically aligned liquid crystal cell. Observation while applying a voltage to the produced liquid crystal cell showed a 200 μm square repetition period, and it was observed that the liquid crystal fell in four directions.

Example 6 A liquid crystal cell was manufactured in the same manner as in Example 4 except that the prism used in Example 1 was used instead of the prism sheet-shaped light refracting element. When the produced liquid crystal cell was observed by crossed Nicols with a polarizing microscope, the liquid crystal cell was found to be a vertically aligned liquid crystal cell. When observation was performed while applying a voltage to the manufactured liquid crystal cell, it was observed that the liquid crystal uniformly fell in one direction. The pretilt angle of the cell was measured using a crystal rotation method.
The pretilt angle was 88 °.

(Example 7) As a photorefractive element, an element having a pyramid-shaped projection formed by digging a large number of grooves in two directions on a surface of a quartz substrate by cutting using diamond. A substrate was prepared by irradiating the alignment film with light in the same manner as in Example 4 except that this photorefractive element was used. By combining this substrate with a substrate not irradiated with light,
A liquid crystal cell was prepared in the same manner as described above.

When the manufactured liquid crystal cell was observed by crossed Nicols with a polarizing microscope, it was found that the liquid crystal cell had a vertical alignment. Observation while applying a voltage to the produced liquid crystal cell showed a 200 μm square repetition period, and it was observed that the liquid crystal fell in four directions.

[0077]

As described above, according to the present invention,
In a method of manufacturing a liquid crystal alignment film using an optical alignment technology that does not have problems such as generation of minute dust and generation of static electricity due to friction in a rubbing method, light is used with high light use efficiency even when a light source having a wavelength distribution is used. And a plurality of irradiation areas can be controlled with high accuracy. Therefore, the orientation uniformity and the division property are excellent, and the operability is also good.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first embodiment of a method for producing a liquid crystal alignment film of the present invention.

FIG. 2 is an explanatory view showing a second embodiment of the method for producing a liquid crystal alignment film of the present invention, and FIG. 2 [1] shows a first state;
FIG. 2B shows the second state.

FIG. 3 is an explanatory view showing a third embodiment of the method for producing a liquid crystal alignment film of the present invention.

FIG. 4 is a graph showing a relationship between a vertex angle below a prism structure and an irradiation angle to an alignment film in the photorefractive element shown in FIG.

FIG. 5 is an explanatory diagram showing a first related art.

FIG. 6 is an explanatory diagram showing a second conventional technique.

FIG. 7 is an explanatory diagram illustrating a diffraction phenomenon caused by a diffraction grating.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Substrate 12 Alignment film 21, 21a Light refraction element 41 Polarization plane changing element 31 Incident light 32, 32a-32d Irradiation light 33 Incident light (polarized) 34a, 34b Irradiated light (polarized)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Daisaku Nakata Inventor F-term (reference) 2H042 BA04 BA14 BA20 CA12 CA17 2H049 BC05 BC22 2H090 HB08Y HB12Y HB13Y HC05, 5-7-1 Shiba, Minato-ku, Tokyo HC16 HC18 KA05 KA11 KA14 KA15 LA07 LA09 LA11 LA16 MA01 MA02 MA03 MA15 MB12 MB14

Claims (16)

[Claims] 1. An alignment film that generates anisotropic liquid crystal alignment ability by light irradiation is formed on a substrate, and light from a light source is applied to the alignment film through a light refraction element that refracts light. Manufacturing method of membrane. 2. The method according to claim 1, wherein the photorefractive element refracts light in a plurality of directions. 3. The method for manufacturing a liquid crystal alignment film according to claim 2, wherein the photorefractive element forms a plurality of regions having different light irradiation directions in one pixel of the alignment film. 4. The method according to claim 3, wherein the plurality of regions are two. 5. The method according to claim 1, wherein the photorefractive element has a triangular prism shape. 6. The method for manufacturing a liquid crystal alignment film according to claim 1, wherein the photorefractive element has a quadrangular pyramid shape. 7. The method according to claim 1, wherein the photorefractive element has a curved surface. 8. The method for manufacturing a liquid crystal alignment film according to claim 1, wherein the photorefractive element includes portions having different refractive indexes. 9. The method for producing a liquid crystal alignment film according to claim 1, wherein polarized light is used as light for irradiating the alignment film. 10. The method for producing a liquid crystal alignment film according to claim 1, wherein light is incident on the inclined surface of the photorefractive element so as to be p-polarized light. 11. The method for manufacturing a liquid crystal alignment film according to claim 1, wherein a polarization plane changing element that changes a polarization plane of light applied to the alignment film is used. 12. The method according to claim 1, wherein the alignment film is a vertical alignment film. 13. The method for manufacturing a liquid crystal alignment film according to claim 1, wherein said alignment film is a horizontal alignment film. 14. A light source, comprising: a light refraction element for refracting light; wherein the light from the light source is refracted through the light refraction element and then applied to a liquid crystal alignment film. A light irradiation device in which a refractive element is arranged. 15. A light source comprising: a light source; a polarization plane changing element for changing a plane of polarization; and a light refraction element for refracting light, wherein light from the light source is refracted through the polarization plane change element and the light refraction element. After that, the light source, the polarization plane changing element and the photorefractive element are arranged so as to irradiate the liquid crystal alignment film. 16. The production of a liquid crystal alignment film according to claim 1, wherein a liquid crystal layer is provided between two substrates, and at an interface between at least one of the two substrates and the liquid crystal layer. A liquid crystal display device provided with an alignment film manufactured by the method.