JP3092899B2 - Liquid crystal display device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TN (Twisted Nematic) mode, a STN (Super Twisted Nematic) mode, and an ECB (Electrically Control) in which liquid crystal droplets are surrounded by polymer walls.
1. Field of the Invention The present invention relates to a liquid crystal display device using an lled birefringence mode, a ferroelectric liquid crystal (FLC) display mode, a light scattering mode, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there are liquid crystal display devices utilizing various display modes. For example, in a liquid crystal display device using an electro-optic effect, a twisted nematic (TN) mode or a super twisted nematic (STN) mode liquid crystal display device using a nematic liquid crystal has been put to practical use. Recently, a liquid crystal display device using a ferroelectric liquid crystal (FLC) has also reached a practical use level.

Recently, utilizing the birefringence of liquid crystal,
A type in which a transparent or opaque state is electrically controlled has been proposed. This type of liquid crystal display device has a display medium in which liquid crystal droplets are dispersed in a polymer between a pair of opposed substrates, and is called a so-called polymer dispersion type liquid crystal display device. In the polymer dispersed liquid crystal display element, basically, when a voltage is applied, the orientation of the liquid crystal molecules becomes uniform in the direction of the electric field, and the ordinary light refractive index of the liquid crystal molecules and the polymer (polymer) serving as a support medium are changed. A display state is obtained by obtaining a transparent state by matching the refractive index, and when no voltage is applied, a light scattering state is generated due to disorder of the orientation of liquid crystal molecules to obtain an opaque state.

However, in the production of the above-mentioned polymer-dispersed liquid crystal display element, liquid crystal droplets are formed by utilizing the phase separation between polymer and liquid crystal in the production method, so that the shape of the liquid crystal droplet is uniform. In addition, it is difficult to accurately control the arrangement of the liquid crystal droplets in the direction along the substrate surface. For this reason, the driving voltage for each liquid crystal droplet is different, the steepness of the threshold in the electro-optical characteristics is inferior, and the driving voltage is relatively high.

On the other hand, in the manufacture of a liquid crystal display element, a substrate gap control material such as a spacer is used to keep a cell gap (substrate gap) constant. This spacer has a distribution density of 25 to maintain the cell gap.
Although it is necessary to use the spacer at about 100 / mm ² , the presence of the spacer in the picture element adversely affects the display quality. For this reason, the following method is considered as a method of reducing the substrate gap control material in the picture element.

(1) A method in which a substrate gap control material is mixed into a seal material, and only the seal material portion is pressed to bond the substrates (Japanese Patent Laid-Open No. 64-61729); Mix the substrate gap control material,
A method in which a substrate is bonded by pressing using a jig having an elastic body so that strong pressure is not applied to the center of the panel (Japanese Patent Application Laid-Open No. 2-139518); Method of patterning so that a wall is formed outside the part (JP-A-60-13152)
No. 1); (4) A method of injecting liquid crystal into cells to which a substrate gap control material has been sprayed, and then moving the spacers remaining in the picture element by static electricity to guide the spacer out of the picture element portion.

In the above-mentioned polymer type liquid crystal display device, during the manufacturing process, a mixture containing a liquid crystal and a photo-curable resin is injected into a gap between a pair of substrates, and the mixture is irradiated with ultraviolet rays so that a liquid crystal is applied to a pixel portion. Form a drop. For this reason, at the time of injecting the mixture, a substrate gap control material such as a spacer needs to be arranged between the substrates, but after the liquid crystal droplet is formed, the liquid crystal droplet itself serves as the substrate gap control material. Therefore, a substrate gap controlling material such as a spacer is substantially unnecessary.

[0008]

In the above-mentioned conventional configuration,
Unnecessary spacers and the like still remain in the picture element, which adversely affects the image quality and contrast of the display picture element.

For example, when a liquid crystal display element in which a spacer remains in a picture element is used in a normally white mode, light passing through the spacer is always blocked, resulting in a reduction in aperture ratio. When the liquid crystal display device is used in a normally black mode, light passing through the spacer is not always blocked, so that light leakage occurs during black display. As described above, in any case, there is a problem that the contrast is reduced. Therefore, in order to obtain a liquid crystal display device with high image quality and high contrast, it is necessary to eliminate spacers in picture elements or reduce them as much as possible.

When the above-mentioned conventional method for reducing the material for controlling the substrate gap existing in the picture element is applied to such a polymer-dispersed liquid crystal display device, the following problems arise.

In the methods (1) and (2) in which the substrate gap controlling material is mixed into the sealing material, there is no spacer in the picture element even when the mixture is injected. For this reason, it is not possible to withstand the volume change of the mixture slightly generated during the ultraviolet irradiation process. In the method of (3), in which the resist film is patterned so that a wall is formed outside the picture element portion, the resist film is It is not applicable because it is an exposure film and its manufacturing method is different. The method (4) of moving the spacers remaining in the picture element by static electricity simply moves the spacers and the like to the periphery of the liquid crystal droplet. For this reason, the spacer remains around the picture element and the aperture ratio is reduced, so that the image quality of the liquid crystal display element is reduced.

As described above, in the conventional method, it is difficult to reduce the number of spacers in the picture element of the polymer dispersed liquid crystal display device.

The present invention solves the above-mentioned conventional problems, and eliminates or reduces a substrate gap control material such as a spacer in a picture element of a polymer-dispersed liquid crystal display element to improve contrast and image quality. An object of the present invention is to provide a liquid crystal display device capable of achieving the above and a method for manufacturing the same.

[0014]

The liquid crystal display element of the present invention comprises a liquid crystal region constituting each picture element or a plurality of picture elements surrounded by a polymer wall in a gap between a pair of substrates arranged opposite to each other. in the liquid crystal display device in which the display medium is sandwiched, the pair of substrates gap control material which is disposed on the substrate gap than the liquid crystal region is composed of easy material present in the polymer in the wall,
Thereby, the above object is achieved.

[0015]

Further, an alignment film made of a material which facilitates the presence of the substrate gap control material in the polymer wall may be provided on at least one of the pair of substrates on the display medium side. Further, a granular spacer can be used as the substrate gap controlling material. Further, a material made of a polymer resin, for example, a material obtained by cutting an optical fiber into a fixed length can be used as the substrate gap controlling material.

Further, the polymer wall may be composed of one kind or a mixture of two or more kinds of fine particles having a different refractive index from the material.

In the method of manufacturing a liquid crystal display element according to the present invention, a surface medium comprising a liquid crystal region constituting each picture element or a plurality of picture elements is surrounded by a polymer wall in a gap between a pair of substrates arranged opposite to each other. A method of manufacturing the sandwiched liquid crystal display element, wherein the pair of substrates are disposed to face each other with a substrate gap control material made of a material that is more likely to be present in the polymer wall than the liquid crystal region therebetween. Injecting a mixed material containing at least a liquid crystal material, a photopolymerizable compound and a photopolymerization initiator into the gap between the pair of substrates; and selectively irradiating the mixed material with ultraviolet light to form a liquid crystal region on a polymer wall. Forming a display medium surrounded by the liquid crystal region, and distributing the substrate gap controlling material more in the polymer wall than in the liquid crystal region, thereby achieving the above object.

[0019]

[0020]

Further, when irradiating the mixed material with ultraviolet rays, a portion corresponding to the picture element portion of the mixed material is covered with a photomask, and the irradiation intensity is selectively varied between the picture element portion and the portion other than the picture element portion. You may. Further, when irradiating the mixed material with ultraviolet light, an irradiation light distribution may be selectively generated by an organic film, an inorganic film, or a metal film formed on the display medium side of at least one of the substrates.

[0022]

In the liquid crystal display device of the present invention, the substrate gap control member disposed between the pair of substrates is made of a material which is more likely to be present in the polymer wall than in the liquid crystal region.
Since the substrate gap control material can be unevenly distributed inside the polymer wall compared to the liquid crystal region, the substrate gap control material in the picture element is eliminated or reduced, and the image quality and contrast of the display picture element are reduced. Improvement is achieved.

In the method of manufacturing a liquid crystal display element according to the present invention, a pair of substrates are opposed to each other with a substrate gap control material made of a material that is more likely to be present in a polymer wall than a liquid crystal region. Then, a mixed material containing at least a liquid crystal material, a photopolymerizable compound and a photopolymerization initiator is injected into the gap between the substrates. When this mixed material is selectively irradiated with ultraviolet light, the photopolymerization reaction speed is high in the part where the ultraviolet light intensity is strong,
Since the photopolymerization reaction speed is slow in the part with low UV intensity,
The liquid crystal is extruded to a portion where the intensity of ultraviolet light is weak, and a liquid crystal droplet is generated. As a substrate gap controlling material, a material that is more likely to be present in the polymer wall than the liquid crystal region and is made of a polymer resin or a granular spacer is used. Is ejected from the liquid crystal region by the surface tension of the polymer, and is taken into the polymer wall made of the photocurable resin.

Further, when irradiating the mixed material with ultraviolet light, a portion corresponding to the pixel portion is covered with a photomask, and the irradiation intensity is selectively changed between the pixel portion and the portion other than the pixel portion. With such a configuration, a liquid crystal region is easily formed in a picture element portion, and a polymer wall is formed in portions other than the picture element portion. In this way, the substrate gap control material can be eliminated or reduced within the picture element. In addition, when an organic film, an inorganic film, or a metal film formed on at least one substrate on the display medium side, such as a transparent electrode, is used instead of the photomask, the irradiation light distribution can be selectively generated more easily. Can be done.

Further, when an alignment film of a material that facilitates the presence of the substrate gap control material in the polymer wall is formed on at least one of the substrates on the display medium side, the alignment film is free of the substrate gap control material. In addition, the substrate gap control material in the picture element is eliminated or further reduced, so that the image quality and contrast of the display picture element are further improved.

Further, by performing phase separation using a material in which a photopolymerizable compound material and fine particles having different refractive indices are mixed, the fine particles are also taken into the polymer wall, and the polymer wall scatters light. Becomes Thereby, it is possible to suppress a decrease in the brightness of the panel. The reason is, for example, 2
In the case of the liquid crystal display mode in which the polarizing plates are set to be orthogonal to each other, there is a problem that the polymer wall portion becomes black because the polymer wall portion is in an isotropic state, and the entire panel becomes blackish and dark. However, in the present invention, since the polymer walls are in a state of scattering light, reduction in panel brightness can be suppressed.

In another method of manufacturing a liquid crystal display device according to the present invention, a large number of substrate gap control members are disposed in at least one of the substrates in a non-picture element region on the substrate, and a pair of substrates are disposed to face each other. A mixed material containing at least a liquid crystal material, a photopolymerizable compound and a photopolymerization initiator is injected into the gap between the substrates. When selectively irradiating this mixed material with ultraviolet light, the portion corresponding to the pixel portion is covered with a photomask, and the irradiation intensity is selectively varied between the pixel portion and the non-pixel portion. As a result, a polymer wall is formed in a non-picture element portion where a large amount of the substrate gap control material is arranged, and a liquid crystal region is formed in a picture element portion where the substrate gap control material is small. Many can be unevenly distributed inside. In addition, when an organic film, an inorganic film, or a metal film formed on at least one substrate on the display medium side, such as a transparent electrode, is used instead of the photomask, the irradiation light distribution can be selectively generated more easily. Can be done.

Further, by performing phase separation using a material in which a photopolymerizable compound material and fine particles having different refractive indices are mixed, the fine particles are also taken into the polymer wall and the polymer wall scatters light. Becomes As a result, for the same reason as before, it is possible to suppress a decrease in the brightness of the panel.

[0029]

Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments and specific examples.

In this specification, the “substrate gap control material made of a material that is more likely to be present in the polymer wall than in the liquid crystal region” is defined as follows. First, a 1 g sample is prepared by mixing a liquid crystal and a photopolymerizable monomer at a ratio of 1: 1. Next, after mixing and stirring the gap control material (0.05 g) to the sample, the mixture is heated at 100 ° C. for 1 hour to obtain a mixed solution. Next, after allowing to cool to room temperature, the mixed solution was dropped on a glass plate (about 2 cmφ), and selectively exposed to a high-pressure mercury lamp for ultraviolet irradiation at an irradiation intensity of 10 mW / cm ² for 20 minutes. And liquid crystal. Next, the ratio of the number of the substrate gap control materials in the polymer wall to the number of the substrate gap control materials in the liquid crystal layer, which has the following relationship, is set in the polymer wall rather than in the liquid crystal region. Is defined as a substrate gap control material made of a material which is easily present in the substrate.

(Number of substrate gap control materials in polymer wall) / (Number of substrate gap control materials in liquid crystal layer)
1 "Orientation film of a material that facilitates the presence of the substrate gap control material in the polymer wall" is defined as follows. First, a liquid crystal and an alignment film material are mixed at a ratio of 1: 1 to prepare a 2 g sample and put it into a bottle. Next, after mixing and stirring the substrate gap control material (0.1 g) with the above sample, the sample is heated at 100 ° C. for 1 hour. Next, after allowing to cool to room temperature, it is allowed to stand for 6 hours to separate into an upper layer (liquid crystal region) and a lower layer (alignment film region). Next, a part of the solution of the upper layer and the lower layer is sucked up with a pipette or the like, and each solution is dropped on a glass plate (about 1 cmφ), and the number of the substrate gap controlling material existing in the alignment film portion and the liquid crystal layer portion are reduced. The one in which the ratio of the number of the existing substrate gap control materials has the following relationship is defined as an alignment film of a material that facilitates the presence of the substrate gap control material in the polymer wall.

(The number of substrate gap controlling materials existing in the alignment film portion) / (the number of substrate gap controlling materials existing in the liquid crystal layer portion) <1.0 That is, when such an alignment film is used, When assembled as a display element, the substrate gap controlling material can be present more in the polymer wall than in the liquid crystal region.

(Embodiment 1) FIG. 1 is a sectional view showing the structure of a liquid crystal display device according to an embodiment of the present invention. In FIG.
The liquid crystal display element includes a pair of substrates 1 made of a glass plate or the like.
a and 1b are disposed to face each other, and a liquid crystal region 6 surrounded by a polymer wall 7 is interposed therebetween to serve as a display medium. Substrate 1
The transparent electrodes 2a, 2b are formed on the display medium side surfaces of the a, 1b.
b is formed, and electrically insulating films 3a, 3
b is formed thereon, and the alignment films 4a and 4b are further formed thereon. The portion where the transparent electrodes 2a and 2b face each other is a picture element portion 12, in which the liquid crystal region 6 is present. Substrates 1a and 1b disposed opposite to each other
Are bonded together by a sealing material 5. Also,
In the gap between the substrates 1a and 1b, there is a spacer 9 as a substrate gap control material. As shown in the plan view of FIG. 2, the spacer 9 has a pixel portion 12 including the liquid crystal region 6.
Are unevenly distributed in the polymer wall 7.

This liquid crystal display element can be manufactured, for example, as follows.

First, an ITO (Indium Tin Oxide) film is deposited to a thickness of 2000 Å on the substrates 1a and 1b by a sputtering method to form strip-shaped transparent electrodes 2a and 2b. Electrical insulating films 3a and 3b are formed by sputtering so as to cover the transparent electrodes 2a and 2b. Further, alignment films 4a and 4b are formed thereon,
Perform rubbing treatment with a nylon cloth or the like. Here, as the substrate material, any material can be used as long as at least one of the substrates is a transparent material that transmits light, and examples thereof include glass and plastic films. Also,
If one substrate is transparent, the other may be a substrate provided with a metal film or the like. As the material of the alignment films 4a and 4b, a material that facilitates the presence of the spacer 9 in the polymer wall is used.

The substrates 9a and 1b in this state are opposed to each other so that the transparent electrodes 2a and 2b are orthogonal to each other, and the spacer 9 is dispersed. As a material of the spacer 9,
It is preferably made of a polymer resin, and more easily conforms to the polymer resin layer than the liquid crystal layer and is easily present in the polymer wall. Examples thereof include spacers made of divinyl, acrylic, styrene, melamine, and the like. . That is, conversely,
Spacers that do not easily exist in the polymer wall, such as silica beads and acrylic beads, are not preferred. Further, it is preferable to use a granular spacer, and it is preferable to use a spacer other than the fixed spacer that is in close contact with the alignment films 4a and 4b of the substrates 1a and 1b.

Then, the ends of the substrates 1a and 1b are adhered to each other with the sealing material 5 to produce a liquid crystal cell.

A mixed material containing at least a liquid crystal material, a photopolymerizable compound, and a photopolymerization initiator is injected into a gap (a gap between the substrates 1a and 1b) of the liquid crystal cell manufactured as described above.

Here, as the liquid crystal material, any of conventional liquid crystal materials used for liquid crystal display devices such as TN mode, STN mode, ECB mode, ferroelectric liquid crystal display mode and light scattering mode can be used. For example, ZLI-4 to which 0.3% of a chiral agent (S-811) is added
792 (Merck). As the photocurable resin, various resins such as R-684 (manufactured by Nippon Kayaku), P-phenylstyrene, isobornyl methacrylate, perfluoromethacrylate, and the like can be used. Further, as a photopolymerization initiator, Irugacu
re651 (made by Ciba Geigy) or the like can be used. In addition, the injection hole at this time is sealed with an ultraviolet (UV) curable resin so that light does not hit the display portion of the substrate in a subsequent ultraviolet irradiation step.

Next, ultraviolet rays are applied to the mixed material from outside the liquid crystal cell. At this time, the substrate to be irradiated with light is covered with a photomask having a light-shielding portion in a portion corresponding to a picture element, and ultraviolet irradiation is performed through the photomask.
For example, a high-pressure mercury lamp for ultraviolet irradiation that can obtain parallel light is used as a light source, and the irradiation position is set at an irradiation intensity of 10 mW / cm ² under the high-pressure mercury lamp. The substrate temperature at the time of this ultraviolet irradiation may be room temperature, or may be a temperature range where the liquid crystal is in an isotropic liquid state between the substrates. In that case, the alignment of the liquid crystal can be stabilized.

By selectively irradiating ultraviolet rays through the photomask in this way, the picture element portion covered by the photomask becomes a light weak irradiation area, and the other part becomes a light strong irradiation area. In the part other than the picture element which is the strong light irradiation area, since the polymerization rate of the photopolymerizable resin is faster than the picture element part which is the light weak irradiation area, the liquid crystal gathers in the picture element part,
The polymer gathers in portions other than the picture elements, and the liquid crystal and the polymer undergo phase separation. As a result, a display medium in which the liquid crystal droplet 6 is surrounded by the polymer wall 7 is formed between the two substrates 1a and 1b.

Therefore, in this phase separation process, the spacer 9 that is likely to be present inside the photopolymerizable resin is repelled from the liquid crystal region by the surface tension of the liquid crystal, and is taken into the polymer resin. As a result, the spacers 9 are unevenly distributed in the polymer wall 7 as compared with the liquid crystal droplets 6, and the amount of the spacers 9 in the picture element can be reduced.

It is to be noted that, instead of the photomask in the ultraviolet irradiation step of the above embodiment, an organic film, an inorganic film, a metal film, or the like formed in the cell.
By using a transparent electrode such as TO or the like, it is possible to easily generate an irradiation light distribution (intensity of irradiation light) easily. Further, when ultraviolet light irradiation is performed at a high substrate temperature in order to stabilize the orientation of the liquid crystal, the substrate is gradually cooled to room temperature in a cooling oven. Slow cooling speed is 3 ℃ / h
To 20 ° C / h, more preferably 5 ° C / h to
10 ° C./h. Further, after the polymer wall 7 is formed, the non-reacted material is cured to seal the spacer 9 in the polymer wall 7 or to sufficiently crosslink the polymer. You may go.

Hereinafter, the phenomenon in which the spacer 9 is incorporated into the polymer wall 7 will be described with reference to FIGS. 3 (a) to 3 (e). As the spacer 9, a granular spacer made of a polymer resin, which is easily present inside the photocurable resin, is used. In addition, the case where the substrate temperature at the time of irradiation is set to a temperature at which the liquid crystal becomes an isotropic liquid state will be described.

FIG. 3A shows a panel before exposure in which the mixed material 13 is injected into the gap between the substrates 1a and 1b. The spacer 9 is scattered over the entire surface of the substrate as a substrate gap control material. In this state, the spacer 9 is in close contact with both substrates.

FIG. 3B shows an ultraviolet irradiation step. A photomask 14 is formed on the light-irradiated side of the substrate 1a so as to cover the picture elements, and is irradiated with ultraviolet rays 8. The light-shielding part 10 as a formation part in the photomask 14 is a light weak irradiation area, and the light transmitting part 11 where the photomask 14 is not formed is a light strong irradiation area. The high light irradiation region has a higher polymerization rate than the low light irradiation region, and the polymer wall 7 as shown by the hatched portion is formed. The substrate temperature at this time is a temperature at which the liquid crystal becomes an isotropic liquid state. When the panel is heated to a temperature close to the liquid crystal phase transition point, the mixed material containing liquid crystal expands, and a space is formed between the spacer and the substrate, which has been in close contact as described above, so that the spacer can move. Then, perform exposure in this state,
By performing slow cooling described below, the spacer can be moved to a target position. This principle of moving the spacer is similarly adopted in other embodiments.

FIG. 3C shows a slow cooling step after ultraviolet (UV) irradiation. At this stage, the phase separation between the liquid crystal and the polymer proceeds, and the liquid crystal region 6 grows. At the same time, due to the surface tension of the liquid crystal, the spacer 9 that is likely to exist inside the photocurable resin is pushed out of the liquid crystal region 6.

When the cooling is further advanced, as shown in FIG. 3D, the liquid crystal region 6 expands, and at the same time, the spacer 9 is further pushed out and gathers on the polymer wall 7. At this point, since the polymer wall 7 is not completely cured and is soft, the spacer 9 which is easily present inside the photocurable resin is taken into the polymer wall 7.

FIG. 3E shows an ultraviolet (UV) irradiation step, in which the unreacted material is cured and the polymer is sufficiently crosslinked. By irradiating the entire surface with ultraviolet light (UV) in this manner, the spacer 9 is confined within the polymer wall 7 indicated by the hatched portion.

The liquid crystal display device thus obtained is
Since the spacers 9 are unevenly distributed in the polymer wall 7, the spacers in the picture element can be eliminated or reduced. Therefore, a liquid crystal display device with high image quality and high contrast can be obtained.

In this liquid crystal display device, the T type is changed by changing the type of liquid crystal injected into the cell and the type of alignment film.
A liquid crystal display element of N mode, STN mode, FLC mode or ECB mode can be used. In addition, a liquid crystal display device using a light scattering mode can be provided, and by providing a polarizing plate or a reflecting plate on both sides of the cell,
A transmissive or reflective liquid crystal display device can also be used.

Hereinafter, a specific example of the above embodiment will be described.

(Specific Example) On the substrates 1a and 1b, ITO
2000 angstrom transparent electrode 2
a and 2b were formed by a sputtering method. This transparent electrode 2
a, an electrically insulating film 3 made of SiO ₂ so as to cover
Was formed by a sputtering method. An alignment film 4 was formed thereon, and this alignment film 4 was rubbed with a nylon cloth. The substrates 1a and 1b in this state are opposed to each other so that the transparent electrodes 2a and 2b are orthogonal to each other, and between them, about 130 granular spacers 9 (micropearl: manufactured by Sekisui Fine Chemical) /
Spray at 1 mmφ. The edge of this substrate was sealed with sealant 5 (Structbond XN-21S, firing temperature: 140 to 15).
(0 ° C./2 h) to produce a liquid crystal cell.

In the gap between the substrates 1a and 1b of this liquid crystal cell,
4 g of ZLI-4792 (manufactured by Merck) containing 0.3% of a chiral agent (S-811) as a liquid crystal material, 0.1 g of R-684 (manufactured by Nippon Kayaku) and P-
0.07 g of phenylstyrene, 0.8 g of isobornyl methacrylate and 0.1 g of perfluoromethacrylate, and Irgacure 651 as a photopolymerization initiator.
A mixed material obtained by mixing 0.03 g (manufactured by Ciba Geigy)
The injection was performed at an ambient temperature of about 30 ° C.

Next, one of the substrates is covered with a photomask 14 so that the picture element portion becomes a light-shielding portion, and an irradiation intensity of 10 mW / c is obtained using a high-pressure mercury lamp capable of obtaining parallel rays.
In the position of the under lamps m ^2, and irradiated with ultraviolet light from the photomask side. After this irradiation, it was gradually cooled in a slow cooling oven. Further, in order to cure the unreacted material and sufficiently perform crosslinking of the polymer, ultraviolet light (UV) irradiation was performed for a short time at a low illuminance.

Finally, a polarizing plate was attached to both outer sides of the liquid crystal cell to produce a TN type liquid crystal display device.

When the thus obtained liquid crystal display device was observed with a microscope, as shown in FIG.
The liquid crystal region was concentrated on 2, and the spacer 9 did not remain in the picture element portion 12. In addition, by using an alignment film made of a material that facilitates the presence of the spacer 9 in the polymer wall, there is no polymer or spacer remaining at the interface between the liquid crystal region and the alignment film, thereby improving the alignment state of the liquid crystal. I was able to. The polymer wall 7 is formed substantially along the photomask pattern in a state where the spacer 9 is taken in the inside, and liquid crystal is taken in the polymer wall 7 or the polymer wall 7 is Did not enter. When the contrast of this liquid crystal display device was measured, it was 30. The contrast was measured by transmitting light through a liquid crystal display element, and was represented by the ratio of the light transmittance when no voltage was applied to the light transmittance when a saturation voltage was applied.

(Comparative Example 1) A TN liquid crystal display device was manufactured in the same manner as in Examples and Specific Examples, except that an adhesive spacer was used as a spacer.

When the thus obtained liquid crystal display device was observed with a microscope, as shown in FIG.
The liquid crystal area was concentrated on the
2 remained within. Further, at the interface between the liquid crystal region and the alignment film, the polymer resin caught by the spacer remained, and the alignment state of the liquid crystal was not good. Polymer wall 7
In some cases, due to the effect of the spacers 9 remaining around the wall, there were portions deviated from the photomask pattern. When the contrast of this liquid crystal display device was measured, it was 23.

(Comparative Example 2) A TN-type liquid crystal display device was produced in the same manner as in Examples and Specific Examples, except that silica beads (manufactured by Kasei Kasei Co., Ltd.) were used as spacers.

When the thus obtained liquid crystal display device was observed with a microscope, as shown in FIG.
However, a part of the spacer 9 was left in the picture element portion 12, and a block of the spacer 9 was formed in the picture element portion 12. Further, in the picture element portion 12, a line of the polymer resin which was caught by the spacer and left a tail remained in some places, and the alignment state of the liquid crystal was not good. The contrast of this liquid crystal display element was measured, and was 20.

Further, when a TN type liquid crystal display device was manufactured using alumina (Alphait: manufactured by Showa Denko) as a spacer, the same result as that obtained by using silica beads was obtained.

In the above-described embodiments and specific examples, the liquid crystal display element in which display is performed by simple matrix driving has been described. However, a TFT (thin film transistor) or a MIM (Metal Insulator Met) is used.
al) can be applied to a liquid crystal display element in which display is performed by active driving or the like, and the driving method is not limited. Further, color display can be performed by forming a color filter or a black mask. In addition to TN mode, STN mode, FLC
The present invention can be similarly applied to a liquid crystal display element in which a liquid crystal used in a mode, an ECB mode, a light scattering mode, etc. is surrounded by a polymer wall, and is applied to both a transmission type liquid crystal display element and a reflection type liquid crystal display element. be able to.

Embodiment 2 An STN-type liquid crystal display device according to Embodiment 2 has the same configuration as that of FIG. In FIG. 1, a liquid crystal display device has a pair of substrates 1a and 1b made of glass plates disposed opposite to each other, and a polymer wall 7 therebetween.
A liquid crystal region 6 surrounded by is sandwiched between them to form a display medium. Strip-shaped transparent electrodes 2a and 2b are formed on the display medium side surfaces of the substrates 1a and 1b, and electric insulating films 3a and 3b are formed so as to cover the transparent electrodes 2a and 2b. These transparent electrodes 2a,
The portion facing 2b is a picture element portion 12, in which the liquid crystal region exists.

The ends of the substrates 1a and 1b provided opposite to each other are adhered by a sealing material 5. Also, the substrate 1a,
A spacer 9 is used as a substrate gap control material in the gap 1b.
Exists. As shown in the plan view of FIG. 2, the spacers 9 are more unevenly distributed in the polymer wall 7 than the picture element portions 12 including the liquid crystal region 6.

This STN type liquid crystal display device can be manufactured, for example, as follows.

First, an ITO (Indium Tin Oxide) film is deposited to a thickness of 2000 Å on the substrates 1a and 1b by a sputtering method, and an electrical insulating film made of SiO _{2 is} formed so as to cover the strip-shaped transparent electrodes 2a and 2b. 3a and 3b are formed by a sputtering method.

Next, polyimide (San Ever 150: manufactured by Nissan Chemical Industries, Ltd.) is applied thereon by spin coating to form alignment films 4a and 4b, and a nylon cloth or the like is unidirectionally applied to the alignment films 4a and 4b. Was rubbed. Each of the transparent electrodes 2a and 2b was four per 1 mm in the width direction, and the interval between adjacent ones was 25 μm.

Next, the two substrates 1a and 1b which have been subjected to the rubbing treatment are opposed to each other so that the orientation treatment directions cross each other at 60 °, and a granular spacer (Hayabeads L11: manufactured by Hayakawa Rubber Co., Ltd.) is interposed therebetween. Spray at 50 pieces / 1 mm ² .

Next, the ends of the two substrates were sealed with a sealing material (Structbond XN-21S, firing temperature: 140 ° C.).
To 150 ° C./2 h) to produce a liquid crystal cell.

Next, a mixed material for a display medium was injected into the gap between the substrates 1a and 1b of the liquid crystal cell at an ambient temperature of about 30.degree. The mixed material for the display medium was 4 g of a liquid crystal material ZLI-4427 (including S-811 manufactured by Merck).
And R-684 (made by Nippon Kayaku Co., Ltd.) as a photocurable resin.
0.1 g, p-phenylstyrene 0.07 g, isobornyl methacrylate 0.8 g, perfluoromethacrylate 0.1 g (the above four are photocurable resins) and photopolymerization initiator , Irgacure6
51 (made by Ciba-Geigy). Here, another curable resin can be used for forming the polymer wall 7. The injection hole is sealed with a commercially available UV curable resin so that light does not hit the display portion of the substrate.

Next, a photomask is placed on one of the substrates so that the picture element portion becomes a light-shielding portion on the liquid crystal cell produced as described above, and the mixed material is irradiated with UV light from the photomask side. In this irradiation, as an example, a high-pressure mercury lamp is used for ultraviolet irradiation that can obtain parallel light from a light source, and the irradiation position is set at 10 mW / cm ² below the high-pressure mercury lamp. The substrate temperature at this time may be set in a temperature range where the liquid crystal state between the substrates becomes an isotropic liquid state. As a means for selectively irradiating light, instead of a photomask, a method of selectively generating irradiation light distribution by using an organic film, an inorganic film, or a metal film formed inside a liquid crystal cell may be used. good.

After the irradiation, if the irradiation is performed at a high temperature in order to stabilize the orientation, the film is gradually cooled to room temperature in a cooling oven. The slow cooling speed may be 3 ° C / h to 20 ° C / h, preferably 5 ° C / h to 10 ° C / h. After the formation of the polymer wall, the substrate is irradiated with UV light for a short period of time at a low intensity to cure the unreacted material, seal the spacer in the polymer wall, and sufficiently crosslink the polymer. You may. The liquid crystal part and the polymer wall part were formed in this way, but the liquid crystal part was 240
° twisted STN orientation.

As shown in FIG. 6, a polarizing plate 17 is bonded to the panel manufactured as shown in FIG. At this time, the polarization direction of the polarizing plate 17 is 45 ° with respect to the rubbing direction as shown in FIG.
The directions were aligned so as to be 60 ° with each other. Thus, a yellow mode transmission type STN liquid crystal display element is manufactured.

In the second embodiment, the transmission type STN liquid crystal display device without a retardation plate is shown. However, the present invention is not limited to this. Can also be adapted. Further, a phase difference plate may be provided to make the display color black and white or the like. Further, a high-contrast liquid crystal display mode can be manufactured by installing a phase difference plate patterned for each picture element in the mode. Further, the material of the substrate is not particularly limited, but a transparent solid that transmits light, for example, glass or a plastic film, and a substrate having one of the substrates including a metal can also be used.

Further, by using a substrate gap control material in which a photopolymerizable compound material and fine particles having different refractive indices are mixed, the fine particles are taken into the polymer wall, and the polymer wall is in a state of scattering light. Can be done.

When the four picture elements (the range shown in FIG. 2) of the liquid crystal cell were observed with a microscope and an SEM, almost no polymer or spacer 9 remained at the interface between the liquid crystal region 6 and the alignment films 4a and 4b. And a good orientation state was obtained.
In addition, since the spacer 9 is incorporated into the polymer wall 7, liquid crystal is not incorporated into the polymer wall 7 and the polymer wall 7 does not enter into the picture element, so that the pattern substantially corresponds to the pattern of the photomask. The polymer wall 7 was formed along. In addition, one of the electro-optical characteristics of the manufactured liquid crystal display element is
One contrast was 15. The contrast was measured by transmitting light through a liquid crystal display element and measuring the contrast. The contrast was represented by the ratio of the light transmittance when no voltage was applied to the light transmittance when a saturation voltage was applied.

When the value used to define the substrate gap control material made of a material that is more likely to be present in the polymer wall than the liquid crystal region described above was examined, it was found that (the number of substrate gap control materials present in the polymer) ÷ The value of (the number of substrate gap control materials present in the liquid crystal portion) was 1.32.

(Comparative Example 3) A liquid crystal display device having the above configuration was produced by replacing the granular spacers of Example 2 with those shown in Table 1 below. Table 1 also shows the contrast of the liquid crystal display element for each of the above configurations.

[0080]

[Table 1]

In the liquid crystal display device described above, the number of spacers present in the picture element is small, the polymer wall is less likely to enter the picture element, and the polymer wall is formed along the photomask pattern. There were many.

In the liquid crystal display device described above, the number of spacers present in the picture element is large, and the spacers around the polymer wall cause the spacers to be caught by the spacers at portions deviating from the photomask pattern. The polymer resin remained.

Further, when the value used for defining the substrate gap controlling material made of a material that is more likely to be present in the polymer wall than in the liquid crystal region was examined, it was found that (the number of substrate gap controlling materials present in the polymer) ÷ The value of (the number of substrate gap control materials present in the liquid crystal portion) was 1.14, 0.53, 0.61, 0.58, and 1.17.

As described above, when a spacer made of a material that is more likely to be present in the polymer wall than in the liquid crystal region is used, the number of spacers present in the picture element is reduced, and the polymer wall enters the picture element. However, since the polymer wall is formed substantially along the photomask pattern, a liquid crystal display device with good contrast can be obtained.

(Embodiment 3) In the present embodiment, the substrate gap controlling member is arranged at an arbitrary position. That is, this is a case where the substrate gap control material is arranged by spacer printing. Also in this case, description will be made in the STN type liquid crystal display mode.

A sectional view of the STN type liquid crystal display element according to the third embodiment is the same as that of FIG.

In FIG. 1, the liquid crystal display element is a display medium in which a pair of substrates 1a and 1b made of glass plates are disposed to face each other, and a liquid crystal region 6 surrounded by a polymer wall 7 is interposed therebetween. ing. Strip-shaped transparent electrodes 2a and 2b are formed on the display medium side surfaces of the substrates 1a and 1b, and electric insulating films 3a and 3b are formed so as to cover them. The portion where the transparent electrodes 2a and 2b face each other is a picture element portion 12, in which the liquid crystal region 6 is present.

The ends of the substrates 1a and 1b provided opposite to each other are adhered by a sealing material 5. Further, the substrates 1a,
A spacer 9 exists as a substrate gap control material in the gap 1b. By arranging the spacers 9 at positions as shown in the plan view of FIG. 7, for example, the spacers 9 can be unevenly distributed in the polymer wall 7.

This STN type liquid crystal display device can be manufactured, for example, as follows.

First, an ITO (Indium Tin Oxide) film is deposited to a thickness of 2000 Å on the substrates 1a and 1b by a sputtering method, and an electrical insulating film made of SiO _{2 is} formed so as to cover the strip-shaped transparent electrodes 2a and 2b. 3a and 3b are formed by a sputtering method.

Next, polyimide (San Ever 150: manufactured by Nissan Chemical Industries, Ltd.) is applied thereon by spin coating to form alignment films 4a and 4b. Since the alignment films 4a and 4b are made of nylon cloth in one direction. A rubbing treatment was performed. Each of the transparent electrodes 2a and 2b had a width of 4 per 1 mm in the width method, and the distance between adjacent ones was 25 μm.

Next, on one of the two substrates 1a and 1b subjected to the rubbing treatment, a granular spacer (Micropearl: manufactured by Sekisui Fine Chemical Co., Ltd.) is dispersed in a versatile UV resin. (Spacer content 3
0 wt%), and printed through a metal screen plate, for example, in one of the patterns shown in FIGS. At this time, either the rubbing step or the spacer printing step may be performed first. When the spacers are printed first, light irradiation or heat application is performed before the rubbing step is performed to cure the UV curable resin or the thermosetting resin containing the spacers. For the printing, a spacer positioner (manufactured by ICTEC Corporation) was used. FIG. 8 shows a printing state when the pattern of FIG. 7B is used. In the printing in FIG. 8, a metal screen plate having holes (10 μmφ) for providing spacers in the pattern of FIG. 7B is placed on a substrate, and the spacers are placed on the screen plate. U
This is performed by moving the V-cured resin or thermosetting resin in the printing direction with a squeegee.

Next, by irradiating with UV, the spacer was fixed on the substrate with a pattern corresponding to those shown in FIGS. 7 (a) to 7 (d).

In this embodiment, the printing patterns shown in FIGS. 7A to 7D are used. However, any pattern may be used as long as it is unevenly distributed more in the polymer wall portion than in the picture element region. Further, in the present embodiment, the spacer is printed on one of the two substrates, but may be printed on both substrates. The type and material of the spacer used may be any.

Next, the two substrates 1a,
1b are opposed to each other so that the rubbing alignment treatment directions are at 60 ° to each other.
(Structbond XN-21S, firing temperature: 140-
(150 ° C./2 h) to produce a liquid crystal cell.

Next, a mixed material for a display medium was injected into the gap between the substrates 1a and 1b of the liquid crystal cell at an ambient temperature of about 30.degree. The mixed material for the display medium was 4 g of a liquid crystal material ZLI-4427 (including S-811 manufactured by Merck), and 0.1 g of R-684 (manufactured by Nippon Kayaku) as a photocurable resin. 0.07 g of p-phenylstyrene,
0.8 g of isobornyl methacrylate and 0.1 g of perfluoromethacrylate (the above four correspond to photocurable resins), and Irgaccu as a photopolymerization initiator
re651 (Ciba Geigy) 0.03 g.

Here, another hardening resin can be used for forming the polymer wall 7. The injection hole is sealed with a commercially available UV curable resin so that light does not hit the display portion of the substrate.

Next, the liquid crystal cell manufactured as described above is
A photomask is placed on one of the substrates so that the picture element portion becomes a light-shielding portion, and the mixed material is irradiated with UV light from the photomask side. For this irradiation, as an example, a high-pressure mercury lamp for ultraviolet irradiation that can obtain parallel light from a light source is used,
The irradiation is performed at a position of 10 mW / cm ² under a high-pressure mercury lamp. The substrate temperature at this time may be set in a temperature range where the liquid crystal state between the substrates becomes an isotropic liquid state. Also,
As a means for selectively irradiating light, a method of selectively generating irradiation light distribution using an organic film, an inorganic film, or a metal film formed inside the liquid crystal cell instead of the photomask may be used.

After the irradiation, if the irradiation is performed at a high temperature to stabilize the orientation, the film is gradually cooled to room temperature in a cooling oven. The slow cooling speed may be 3 ° C / h to 20 ° C / h, preferably 5 ° C / h to 10 ° C / h. After the formation of the polymer wall, the substrate may be irradiated with UV light for a short period of time at low illuminance in order to cure the unreacted material and sufficiently crosslink the polymer. The liquid crystal part and the polymer wall part were formed in this way,
The liquid crystal section had a 240 ° twisted STN orientation.

As shown in FIG. 6, a polarizing plate 17 is bonded to the liquid crystal panel manufactured as shown in FIG. At this time, the polarization directions of the polarizing plates 17 were adjusted to 45 ° with respect to the rubbing direction and 60 ° with each other as shown in FIG. Thus, a yellow mode transmission type STN liquid crystal display element is manufactured.

When the four picture elements of the liquid crystal panel were observed with a microscope and an SEM, it was found that the spacer was present at a position substantially in accordance with the pattern of the screen plate, and a polymer wall was formed substantially along the photomask pattern. The contrast, which is one of the electro-optical characteristics of the manufactured liquid crystal panels, is 15 for the liquid crystal panels manufactured using the patterns shown in FIGS. 7A, 7B, 7C, and 7D. The contrast was the same as that of the liquid crystal panel of Example 2. The contrast was measured by a method in which light was transmitted through a liquid crystal panel and measured. The contrast was represented by the ratio of the light transmittance when no voltage was applied to the light transmittance when a saturation voltage was applied.

In this embodiment, the transmission type S without a retardation plate is used.
Although the embodiment of the TN liquid crystal display element has been described, the present invention is not limited thereto, and the present invention can be applied to a reflection type STN liquid crystal display element by providing a reflection plate. Furthermore, by providing a phase difference plate,
The display color may be black and white or the like. Further, a high-contrast liquid crystal display mode can be manufactured by installing a phase difference plate patterned for each picture element in the mode. The material of the substrate is not particularly limited, but a transparent solid that transmits light, for example, glass or a plastic film, and a substrate having one of the substrates including a metal can also be used.

Further, by using a substrate gap control material in which a photopolymerizable compound material and fine particles having different refractive indices are mixed, the fine particles are taken into the polymer wall, and the polymer wall is in a state of scattering light. can do.

Example 4 Example 4 is a case where the polymer wall contains fine particles having a different refractive index from that of the material.

In this example, an STN-type liquid crystal display device was manufactured in the same manner as in Example 2 except for the mixed material injected into the gap between the liquid crystal cells composed of a pair of substrates.

The above mixed material is composed of 4 g of a liquid crystal material ZLI-
4427 (including S-811 manufactured by Merck) and 0.1 g of R-684 (manufactured by Nippon Kayaku) as a photocurable resin.
0.07 g of p-phenylstyrene, 0.8 g of isobornyl methacrylate, 0.1 g of perfluoromethacrylate (the above four correspond to photocurable resins), and Irgacure 651 as a photopolymerization initiator.
0.03 g (manufactured by Ciba-Geigy) and niobium oxide sol as fine particles (particle diameter 0.5 μm, refractive index n = 1.43)
2) A mixture of 0.6 g was used. Note that the refractive index of the polymer resin is n = 1.174.

In the liquid crystal display device manufactured in this embodiment, the fine particles exist in the entire panel. However, since the fine particles have a small particle size, they do not affect the image quality and contrast of the panel even if they exist in the picture element portion. Therefore, the fine particles also exist inside the polymer wall. Brightness of liquid crystal display element of this configuration (L ^* value)
Was measured with a Minolta spectrophotometer (CM-1000), and the L ^* value was 41.3. Example 2
In place of the L ^* value of the produced panel, were measured by Minolta spectrophotometer (CM-1000), L ^* value = 38.
It was one. Therefore, in the case of the present embodiment, the mixing of the fine particles can improve the L ^* value by about 8%. As a result, the brightness of the panel can be improved by mixing fine particles having a different refractive index from the polymer resin in the mixed material.

As the fine particles, other than the materials used in the above examples, any fine particles may be used as long as the refractive index is different from that of the polymer resin and the particle size is smaller than that of the spacer. In this embodiment, one kind of fine particles is used. However, the present invention is not limited to this.
Of course, the same effect can be obtained by using more than one kind of fine particles.

[0109]

As described above, according to the present invention, the substrate gap controlling material is unevenly distributed in the polymer wall, and the substrate gap controlling material in the picture element is eliminated or reduced. Image quality and contrast can be improved. In addition, as a means for unevenly distributing the substrate gap control material in the polymer wall, a method using a substrate gap control material that is more easily present in the polymer wall than the liquid crystal region, and a method in which the substrate gap control material is arranged by printing There is.

In the case of using a substrate gap controlling material which is more likely to be present in the polymer wall than in the liquid crystal region, the liquid crystal can be used even if the substrate gap controlling material is a polymer resin or a granular spacer is used. In the phase separation process between the polymer and the polymer, the substrate gap control material is repelled from the liquid crystal region by the surface tension of the liquid crystal, and the substrate gap control material can be taken into the polymer wall made of the photocurable resin.
Furthermore, when an alignment film of a material that facilitates the presence of the substrate gap control material in the polymer wall is formed on at least one of the substrates on the display medium side, the substrate gap control material can be eliminated from remaining in the alignment film. In addition, the substrate gap control material in the picture element is eliminated or further reduced, so that the image quality and contrast of the display picture element can be further improved.

When the substrate gap controlling material is arranged by printing, the substrate gap controlling material can be arranged at an arbitrary position. Can be unevenly distributed.
Further, the substrate gap controlling material can be used more effectively than the spraying method.

Further, when irradiating the mixed material of the liquid crystal and the photopolymerizable resin with ultraviolet rays, the portion corresponding to the pixel portion is covered with a photomask, and the irradiation intensity is selected between the pixel portion and the portion other than the pixel portion. If they are different from each other, a liquid crystal region can be easily formed in a picture element portion with a simple configuration, and a polymer wall can be easily formed in portions other than the picture element portion. In this way, the substrate gap control material can be eliminated or reduced within the picture element. In addition, when an organic film, an inorganic film, or a metal film formed on at least one substrate on the display medium side, such as a transparent electrode, is used instead of the photomask, the irradiation light distribution can be selectively generated more easily. Can be done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to one embodiment of the present invention.

FIG. 2 is a plan view showing the liquid crystal display device of FIG.

3 (a) to 3 (e) are cross-sectional views of the liquid crystal display device for explaining a phenomenon in which a spacer is taken into a polymer wall in the method of manufacturing the liquid crystal display device of FIG.

FIG. 4 is a plan view showing a liquid crystal display device of Comparative Example 1.

FIG. 5 is a plan view showing a liquid crystal display device of Comparative Example 2.

FIG. 6 is a cross-sectional view showing a state in which a polarizing plate is attached to the panel manufactured in Example 2.

FIGS. 7A to 7D are plan views showing various patterns when printing is performed using a screen plate in the third embodiment.

FIG. 8 is a perspective view showing a printing state when printing is performed in the pattern of FIG. 7B.

FIG. 9 is a plan view showing a polarization axis and a rubbing direction of panels manufactured in Examples 2 and 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1a, 1b Substrate 2a, 2b Transparent electrode 3a, 3b Electric insulating film 4a, 4b Alignment film 5 Sealing material 6 Liquid crystal region 7 Polymer wall 8 Ultraviolet 9 Spacer 10 Light shielding part 11 Light transmitting part 12 Picture element 13 Mixed material 14 Photo mask 17 Polarizing plate

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-281558 (JP, A) JP-A-5-188383 (JP, A) JP-A-5-297382 (JP, A) JP-A-1- 266509 (JP, A) JP-A-6-175109 (JP, A) JP-A-6-301040 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1339 500 G02F 1/1334

Claims (8)

(57) [Claims] 1. A liquid crystal display device in which a display medium in which a liquid crystal region constituting each picture element or a plurality of picture elements is surrounded by a polymer wall is sandwiched between a pair of opposed substrates. A substrate gap control member disposed in the pair of substrate gaps,
A liquid crystal display device made of a material that is more likely to be present in the polymer wall than the liquid crystal region. 2. An alignment film is provided on a display medium side of at least one of the pair of substrates, and the alignment film is made of a material that facilitates the presence of the substrate gap control material in the polymer wall. Item 2. A liquid crystal display device according to item 1. 3. The liquid crystal display device according to claim 1, wherein the substrate gap controlling material is a granular spacer. 4. The liquid crystal display device according to claim 1, wherein the substrate gap controlling material is made of a polymer resin. 5. The liquid crystal display device according to claim 3, wherein the polymer wall is made of one kind or a mixture of two or more kinds of fine particles having a different refractive index from the material of the polymer wall. 6. A liquid crystal display device having a display medium in which a liquid crystal region constituting each picture element or a plurality of picture elements is surrounded by a polymer wall in a gap between a pair of substrates arranged opposite to each other. In the method, a step of disposing the pair of substrates to face each other with a substrate gap control material made of a material that is more likely to be present in the polymer wall than the liquid crystal region interposed therebetween; Injecting a mixed material containing at least a material, a photopolymerizable compound and a photopolymerization initiator, and selectively irradiating ultraviolet light to the mixed material to form a display medium in which a liquid crystal region is surrounded by polymer walls. And unevenly distributing the substrate gap control material inside the polymer wall compared to the liquid crystal region. 7. When irradiating the mixed material with ultraviolet light,
7. The method according to claim 6, wherein a portion corresponding to the pixel portion of the mixed material is covered with a photomask, and the irradiation intensity is selectively changed between the pixel portion and the portion other than the pixel portion. 8. When irradiating the mixed material with ultraviolet light,
The method according to claim 6 , wherein the irradiation light distribution is selectively generated by an organic film, an inorganic film, or a metal film formed on at least one of the substrates on the display medium side.