JPH07104249A - Liquid crystal display device and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] A liquid crystal display element in which the roughness of the display screen is eliminated, the display quality is remarkably improved, and the display quality is improved even when the liquid crystal display element is viewed from any direction. The present invention provides a method for manufacturing a liquid crystal display element, which can significantly improve the display quality of the manufactured liquid crystal display element. [Structure] The liquid crystal display element 11 includes a pair of glass substrates 1
The liquid crystal layer 14 is sandwiched between 2 and 13. A plurality of picture element electrodes 15 are formed in a matrix on one substrate 12, and a common electrode 16 is formed on the other substrate 13. A polymer wall film 1 is provided between the substrates 12 and 13.
7 are formed in a matrix. The picture element electrode 1
5, each picture element 19 includes the common electrode 16 and the liquid crystal layer 14 sandwiched between the picture element electrode 15 and the common electrode 16.
At this time, the refractive index n _p of the polymer wall 17 is set to the liquid crystal molecule 33.
Ordinary refractive index n _o and random state refractive index (n _o + n _e ).
Set between / 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a manufacturing method, and more particularly to a liquid crystal display device having a structure in which a liquid crystal region for each picture element is surrounded by a polymer material,
The polymer material and the liquid crystal in the liquid crystal region for each pixel have a common arrangement, and TN (Twisted Nematic), STN (S
upper Twisted Nematic), ECB (Electrically Conrt)
oled Birefringence), FLC (Ferroelectric Liquid)
A liquid crystal display device in which a conventional mode liquid crystal layer such as Crystal) is substantially surrounded by a polymer wall.

[0002]

2. Description of the Related Art Conventionally, a TN type or STN type liquid crystal display element using a nematic liquid crystal has been put into practical use as a display element utilizing the electro-optical effect. A liquid crystal display element using a ferroelectric liquid crystal has also been proposed. These liquid crystal display elements require a polarizing plate and require an alignment treatment. On the other hand, there is known a method of forming a film by dispersing liquid crystal droplets in a polymer by encapsulating a liquid crystal, which does not require a polarizing plate and does not require an alignment treatment. Here, gelatin, gum arabic, polyvinyl alcohol and the like have been proposed as substances that can be encapsulated (Japanese Patent Publication No. 58-501631, USP 443504).
7).

In this prior art, the ordinary refractive index n _o of the liquid crystal molecules and the refractive index n _{p of the} polymer medium are basically matched, and a transparent state is displayed when a voltage is applied to align the liquid crystals. ,
When the orientation of the liquid crystal molecules when no voltage is applied becomes random, since the refractive index of the liquid crystal droplets is deviated from n _o, the liquid crystal - cause light scattering at the polymer interface, displays the opaque state. Therefore, in order to achieve sufficient translucency when an electric field is applied, the materials of the liquid crystal and the polymer film must be sufficiently selected so that the refractive index of the liquid crystal and the refractive index of the polymer are close to each other. I have to. Regarding such a conventional technique, Japanese Patent Laid-Open No.
In JP-A-3-43993 and JP-A-3-245120, the ratio of the ordinary refractive index of the liquid crystal to the refractive index of the polymer film is 0.98 to
A method of manufacturing a transparent liquid crystal panel by setting the ratio to 1.02 is disclosed.

Recently, the inventors of the present invention have a pair of substrates, at least one of which has a light-transmitting property, of a mixture of a liquid crystal material, a photocurable resin, and a photopolymerization initiator in the peripheral portion thereof. Liquid crystal cell sealed with a sealing material, and then put a photomask so that the picture element part becomes a light-shielding part, and irradiate with ultraviolet rays to collect the liquid crystal area in the picture element part, A liquid crystal display device in which polymer materials were collected was prepared. In the liquid crystal display element of the present invention, when nematic liquid crystal is used and the liquid crystal domain is in a radial or random state within a pixel, the viewing angle characteristics of the liquid crystal display element are significantly improved as compared with the TN liquid crystal display element. It

This is explained as follows. Figure 5
FIG. 3 is a cross-sectional view of a conventional TN type liquid crystal display element 1.
For example, the TN type liquid crystal display element has a structure in which a liquid crystal layer 4 is sandwiched between a pair of substrates 2 and 3 as shown in FIG.
The liquid crystal molecules 5 of the liquid crystal layer 4 have a structure in which the initial orientation is twisted by 90 ° and the liquid crystal molecules rise in one direction at an angle (pretilt angle). Therefore, when the drive voltage is applied from the power source 6, as shown in FIG. 5C, the alignment treatment is performed so that the liquid crystal molecules 5 rise in the same direction. Therefore, when the liquid crystal molecules 5 rise in the halftone display, the liquid crystal molecules 5 are tilted in the same direction as shown in FIG. 5B.

For this reason, when the liquid crystal molecules 5 are viewed from the respective directions indicated by the arrow A and the arrow B having relatively wide angles with each other as shown in the figure, the apparent refractive index is different. become. As a result, the contrasts of the images viewed from the respective directions A and B are greatly different, and in extreme cases, a display abnormality such as an image inversion phenomenon occurs. in this way,
In the conventional display mode, poor viewing angle characteristics pose a problem.

[0007] A liquid crystal display device having a polarizing plate, in which phase separation of a liquid crystal and a polymer material is regularly performed by using a photomask, has a polymer wall made of a polymer material between respective substrates, Liquid crystal drops surrounded by polymer walls are formed. In this liquid crystal droplet, when a voltage is applied, the liquid crystal molecule rises toward each polymer wall due to the interaction between the liquid crystal molecule and the polymer wall. Therefore, the apparent refractive index of the liquid crystal molecules seen from each direction as described above becomes substantially the same, which is a great effect in improving the viewing angle characteristics.

[0008]

In the liquid crystal display element in which liquid crystal droplets are formed in the polymer film, the liquid crystal region is oriented radially or randomly with respect to the pixel center. For this reason, in the liquid crystal display device, when the refractive index difference between the polymer walls arranged in a matrix and the liquid crystal is large, local light scattering occurs at the interface between the polymer wall and the liquid crystal.
Therefore, there is a problem that the display screen is remarkably rough and the display quality is low.

The present invention has been made in order to solve the above problems, and the roughness of the display screen is eliminated, the display quality is remarkably improved, and when the liquid crystal display element is viewed from an arbitrary direction. Another object of the present invention is to provide a liquid crystal display element having improved display quality, and to provide a method for manufacturing a liquid crystal display element capable of significantly improving the display quality of the manufactured liquid crystal display element. Is the purpose.

[0010]

A liquid crystal display element of the present invention comprises a liquid crystal layer sandwiched between a pair of substrates, at least one of which is transparent, and a plurality of picture elements formed including the liquid crystal layer. The pixels are arranged in a matrix, and each pixel has a liquid crystal region surrounded by a polymer film, and the refractive index (n _p ) of the polymer
But ordinary refractive index of the liquid crystal composition (n _o) and extraordinary refractive index with respect to the _{(n e), n o -0.04} ≦ n p ≦ (n e +
n _o ) / 2, which achieves the above object.

In the present invention, at least one liquid crystal domain may exist in the one picture element, and the coordination of each liquid crystal domain may be random or radial.

In the present invention, an insulating film for orienting liquid crystal molecules may be provided on the surfaces of the respective substrates which face each other.

In the present invention, a polarizing plate may be provided on at least one of the pair of substrates.

In the method for manufacturing a liquid crystal display device of the present invention, a liquid crystal layer is sandwiched between a pair of substrates, at least one of which is transparent, and a plurality of picture elements formed including the liquid crystal layer are arranged in a matrix. A method for producing a liquid crystal display element arranged in a pattern, comprising: a photopolymerizable resin, a photopolymerization initiator, and a composite film containing a liquid crystal layer and a polymer film obtained by curing the photopolymerizable resin. refractive index of the molecular film (n _p) is, with respect to the ordinary refractive index of the liquid crystal layer (n _o), the extraordinary refractive index _{(n e), n o -0} .
A mixture containing a liquid crystal compound set to 04 ≦ n _p ≦ (n _e + n _o ) / 2 is caused to undergo phase separation due to a polymerization reaction by light having a regular irradiation intensity unevenness, thereby causing a gap between the pair of substrates. The method includes the step of regularly distributing the polymer and the liquid crystal material, thereby achieving the above object.

In the present invention, a light-shielding portion that substantially weakens the intensity of the irradiated light in the picture element is provided, and then,
The mixture may be irradiated with light.

[0016]

In order to solve the above problems, the present inventors have
In creating a liquid crystal cell surrounded by polymers, we conducted a diligent study to build a high-contrast liquid crystal panel without roughness. As a result, the refractive index (n _p ) of the polymer film after polymerization and curing is expressed by the following inequality regarding the ordinary refractive index (n _o ) and the extraordinary light refractive index (n _e ) of the liquid crystal composition.

[0017]

[Number 1] _{n o -0.04 ≦ n p ≦ (} n e + n o) / 2 liquid crystal was set to satisfy the - phase separation of the polymer composite material, upon polymerization the liquid crystal droplets and the polymer wall It was confirmed that by selectively controlling the process, it is possible to create a liquid crystal display device having high viewing angle characteristics and excellent display quality.

The present invention will be described in more detail below.

In the liquid crystal display device of the present invention, each of a plurality of picture elements arranged in a matrix has at least one liquid crystal domain surrounded by a polymer wall and having different orientations. In a liquid crystal display device having at least one liquid crystal domain having different orientations surrounded by a polymer, when a voltage is applied, liquid crystal molecules stand vertically with respect to the substrate surface, so that an apparent The refractive index is n _o , and when no voltage is applied, the apparent refractive index is (n _e + n _o ) / 2 because the liquid crystal molecules are aligned horizontally with respect to the substrate surface. The eye of the present invention is to suppress the light scattering caused by the difference in refractive index between the liquid crystal and the polymer, so that the roughness of the screen is not noticeable.

The ratio CR (contrast) between the transmittance (T _OFF ) when no voltage is applied and the transmittance (T _ON ) when voltage is applied is
When defined by CR = T _OFF / T _ON , it is very effective to reduce the transmittance T _ON in order to increase the contrast. Then, in the n _p is varied in n _o the vicinity,
As a result of examining the influence on T _ON , as shown in FIG.
It is very effective to suppress the difference between n _p and n _o within 0.04 when producing a liquid crystal display device of the present invention which has a high contrast and has no roughness.

As the refractive index limitation range of the liquid crystal and the polymer in the present invention, in the schematic view of the refractive index between the liquid crystal and the polymer shown in FIG. 4, (A) the refractive index n _{p of the} polymer wall and the liquid crystal When the absolute value of the difference from the ordinary light refractive index n _o is 0.04 or more, the roughness during voltage application becomes noticeable.

(B) When the difference between the refractive index n _{p of the} polymer wall and the refractive index (n _o + n _e ) / 2 in the random state becomes large,
Roughness becomes noticeable when no voltage is applied.

(C) The refractive index n _p of the polymer wall is calculated as _follows:
By setting between -0.04 and the refractive index _{(n o + n e) /} 2, it can reduce the change in refractive index difference with respect to voltage change.

The change in the refractive index of the liquid crystal molecules from n _o to (n _e + n _o ) upon the change from the voltage applied state to the time when no voltage is applied.
/ 2, and the difference in refractive index from the refractive index n _p of the polymer wall is [n _p
-N _o ] to [n _p − (n _e + n _o ) / 2],
The refractive index n _p of the inequality _{n o ≦ n p ≦ (n} e + n o) / 2 With the range satisfying the refractive index difference (n _o -n _{e)
/ 2~ (n e -n o)} / can be minimized in the second range to become. As a result, the roughness of the display screen can be eliminated.

[0025]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto.

(Embodiment 1) FIG. 1 is a sectional view of a TN type liquid crystal display element 11 according to an embodiment of the present invention. For example, TN
The liquid crystal display element 11 has a structure in which a liquid crystal layer 14 is sandwiched between a pair of glass substrates 12 and 13. One substrate 12
A plurality of pixel electrodes 15 are formed in a matrix on the upper side, and a common electrode 16 is formed on the other substrate 13. A polymer wall film 17 is formed in a matrix between the substrates 12 and 13. Each liquid crystal drop 19 is formed by including the picture element electrode 15, the common electrode 16, and the liquid crystal layer 14 sandwiched between the picture element electrode 15 and the common electrode 16, and each picture element 27 includes each liquid crystal drop 19. It is formed.

The method of manufacturing the liquid crystal display element 11 of this embodiment will be described below.

A pair of glass substrates (for example, a plate thickness of 1.1 m
m) a pair of display substrates 20 and 21 each having ITO (a mixture of indium oxide and tin oxide, for example, a film thickness of 50 nm) as transparent pixel electrodes 15 and common electrodes 16 on 12 and 13, respectively. A cell was constructed by keeping the cell thickness with a cylindrical or fibrous spacer (not shown) having a diameter of 6 μm. This cell has a structure in which the pair of display substrates 20 and 21 are arranged with a space therebetween by the spacer, and the display substrates 20 and 21 are sealed with a sealing material at their peripheral portions.

A photomask 25 shown in FIG. 2 is placed on the prepared cell. In this photomask 25,
A plurality of rectangular light-shielding regions 22 are formed in a matrix, a light-transmitting region 23 is formed between each light-shielding region 22, and a circular light-transmitting hole 24 is provided at the center of each light-shielding region 22 as an example. Each has a formed structure.

4 g of ZLI-4792 (manufactured by Merck) in which 0.3% by weight of a chiral agent S-811 (manufactured by Merck) was added as a liquid crystal material into the liquid crystal display cell thus prepared, and as a photocurable resin composition. R-684 (Nippon Kayaku Co., Ltd.)
1 g, p-phenylstyrene 0.05 g, isobornyl methacrylate 0.85 g and photopolymerization initiator Irgacure65
A mixture was prepared by mixing 0.0025 g of 1 (manufactured by Ciba Geigy). When the liquid crystal-polymer mixture thus prepared was heated and observed, the homogenization temperature of the mixture was 32 ° C.

The process of forming the liquid crystal layer 14 will be specifically described. The mixture was injected at 34 ° C., and then kept at a temperature of 10 mW / cm ² under a high-pressure mercury lamp where parallel rays can be obtained from the dot pattern side of the photomask 25 (UV light irradiation for 1 second, 30 seconds). The light irradiation process (without second irradiation) was performed for 20 cycles, and then UV light was irradiated for 5 minutes. Then, in that state, U for 10 minutes at the same UV intensity
After performing V light irradiation, the photomask was removed, and ultraviolet rays were irradiated for 5 minutes to cure the photocurable resin material in the mixture.

FIG. 3 is a plan view of the liquid crystal display cell of this embodiment. In this way, when the liquid crystal display element 11 in which the liquid crystal layer 14 is formed between the pair of display substrates 20 and 21 of the liquid crystal display cell is observed with a polarization microscope, as shown in FIG. In this structure, a plurality of liquid crystal domains 30 are radially or randomly aligned from the central island-shaped portion. In addition, the liquid crystal layer 1 within the range of the picture element 27
In No. 4, the disclination 31 was formed in a radial or random shape in the portion corresponding to the interface of the liquid crystal domain 30.

Before and after the prepared liquid crystal display cell, two polarizing plates whose polarization axes are orthogonal to each other are attached to each other to form a liquid crystal drop 1.
A liquid crystal display element 11 in which 9 was surrounded by a polymer wall 17 was prepared. The electro-optical characteristics of the produced liquid crystal display element 11 were measured as follows using a liquid crystal evaluation device LCD-5000 (manufactured by Otsuka Electronics Co., Ltd.). The same polarizing plate was attached to the liquid crystal display cell in a parallel Nicol state, and the transmittance was set to 100% to be in a normally white state. Halogen lamp light was incident on the liquid crystal display element 11 from a direction perpendicular to the substrates 12 and 13. With the light entering in this way,
As shown in FIGS. 1A to 1C, the electric field in the liquid crystal layer 14 is switched by applying a voltage to the liquid crystal display element 11 or applying no voltage to the liquid crystal display element 11. . At this time, as an example, the emitted light at a position inclined by 40 ° vertically and horizontally from the vertical direction of the liquid crystal display element 11 is measured in each direction using a lens having a converging angle of 24 °, and is measured in each direction. The average value of the respective ratios T ₀ / T _Sat of the light transmittance T _O when the electric field is OFF and the light transmittance T _Sat when the saturation voltage is applied is defined as the contrast ratio.

In order to measure the refractive index of the polymer wall 17, 0.3 g of the photocurable resin composition having the same composition ratio as in this example and 0.0015 g of the photopolymerization initiator Irugacure 651 were mixed, and the thickness of each plate was adjusted. The resin was injected into a liquid crystal display cell composed of a combination of 6 μm glass substrates, and was irradiated with ultraviolet light for 3 minutes at a position where the irradiation light amount by a high pressure mercury lamp was 10 mW / cm ² to cure the resin. Then the cured polymer wall 17
From the glass substrate, using an Abbe refractometer,
The refractive index was measured at room temperature (25 ° C). The results of these measurements are summarized and shown in Table 1 below.

Further, in the present embodiment, since the phase separation between the liquid crystal and the polymer wall 17 is regularly controlled by utilizing the photomask 25, the liquid crystal domain 30 in the liquid crystal droplet 19 is as described above. The structure is oriented radially or randomly, and the rising directions of the liquid crystal molecules are almost omnidirectional when a voltage is applied, so that the viewing angle characteristics of the liquid crystal display element 11 of this embodiment are improved.

That is, as shown in FIG. 1 (2), the interaction between the liquid crystal molecules 33 and the polymer wall 17 when a voltage is applied causes
Since the liquid crystal molecules 33 tilt in any direction, the liquid crystal layer 1
The apparent refractive index of 4 is substantially the same in the directions of the arrow A and the arrow B, and the viewing angle characteristic is improved.

The main point of this embodiment is to suppress the light scattering caused by the difference in the refractive index between the liquid crystal droplet 19 and the polymer wall 17 and eliminate the roughness of the display screen. Therefore, the ratio CR (contrast) between the transmittance (T _OFF ) when no voltage is applied and the transmittance (T _ON ) when voltage is applied is CR =
When defined by T _OFF / T _ON , it is very effective to reduce the transmittance T _ON in order to increase the contrast. Therefore, as a result of examining the influence on T _ON by changing n _p in the vicinity of n _o , as shown in FIG. 6, it is possible to suppress the difference between n _p and n _o within 0.04. The present invention is very effective in producing a high-contrast liquid crystal display device having no roughness realized by the liquid crystal display device of the present invention.

As the refractive index limitation range of the liquid crystal and polymer in the present invention, in the schematic view of the refractive index between the liquid crystal and the polymer shown in FIG. 4, (A) the refractive index n _{p of the} polymer wall and the liquid crystal When the absolute value of the difference from the ordinary light refractive index n _o is 0.04 or more, the roughness during voltage application becomes noticeable.

(B) When the difference between the refractive index n _{p of the} polymer wall and the refractive index (n _o + n _e ) / 2 in the random state becomes large,
Roughness becomes noticeable when no voltage is applied.

(C) The refractive index n _p of the polymer wall is calculated as _follows:
By setting between -0.04 and the refractive index _{(n o + n e) /} 2, it can reduce the change in refractive index difference with respect to voltage change.

Example 2 A chiral agent S as a liquid crystal material
ZLI containing 0.38% by weight of -811 (Merck)
-5080 (manufactured by Merck & Co.) 4 g, as photocurable resin composition n-butyl methacrylate 0.1 g, perfluorooctyl methacrylate 0.85 g, styrene 0.05
g, and a photopolymerization initiator Irugacure 651 (manufactured by Ciba-Geigy) 0.0025 g. Similarly, a mixture of a photocurable resin and a photopolymerization initiator was prepared. Then, a resin film composed of the liquid crystal display element 11 and the polymer wall 17 was prepared in the same manner as in Example 1, and the respective refractive indexes were measured. The measurement results are shown in Table 1 below.

(Comparative Example 1) A chiral agent S as a liquid crystal material
ZLI containing 0.38% by weight of -811 (Merck)
-5048-000 (manufactured by Merck Ltd.) 4 g, R-604 which is a bifunctional acrylate as a photocurable resin composition.
0.95 g (manufactured by Nippon Kayaku Co., Ltd.), 0.05 g of styrene, Irugacure 651 (manufactured by Ciba Geigy) of photopolymerization initiator.
A mixture with 0025 g was made. Similarly, a mixture of a photocurable resin and a photopolymerization initiator was prepared. Then, in the same manner as in Example 1, a liquid crystal display element and the resin film were prepared and the respective refractive indexes were measured. The results are shown in Table 1 below.

(Comparative Example 2) Chiral agent S as a liquid crystal material
ZLI containing 0.38% by weight of -811 (Merck)
-4281 (manufactured by Merck), R-684 (manufactured by Nippon Kayaku Co., Ltd.) 0.95 g as a photocurable resin composition, styrene 0.05 g, and a photopolymerization initiator Irugacure 651 (manufactured by Ciba Geigy) 0.0025 g. A mixture was made. Similarly, a mixture of a photocurable resin and a photopolymerization initiator was prepared. Then, in the same manner as in Example 1, a resin film composed of the liquid crystal display element and the polymer wall 17 was prepared, and each refractive index was measured. The results are shown in Table 1 below.

From Table 1, as in Examples 1 and 2 of the present invention, the refractive index n _p of the polymer wall 17 is determined by the liquid crystal molecule 3
3 of the ordinary refractive index n _o, with respect to extraordinary refractive index n _e, as defined in the number _{1, n o -0.04 ≦ n p} ≦ (n
_e + n _o ) / 2. As a result, the difference in refractive index between the liquid crystal layer 14 and the polymer wall 17 becomes small, and light scattering at the interface between the liquid crystal layer 14 and the polymer wall 17 becomes small. For this reason, the roughness of the display screen becomes inconspicuous,
The contrast was found to be relatively high.

[0045]

[Table 1]

(Comparative Example 3) As the liquid crystal material, the same liquid crystal as that used in Example 1 (ZLI-4792 (manufactured by Merck)), and as the resin material, the resin (R-
684 (0.95 g) and styrene 0.05 g) were mixed with a photopolymerization initiator, and a resin film comprising a liquid crystal display device and the polymer wall was prepared in the same manner as in Example 1. Was prepared, and the electro-optical characteristics of the liquid crystal display device and the refractive index of the resin film were measured. The results are shown in Table 1 above.

Comparing Example 1 and Comparative Example 3, even if the same liquid crystal is used, if the difference between the refractive index of the resin and the refractive index of the liquid crystal is out of the range defined by the present invention, the contrast is increased. It was confirmed that it was significantly reduced.

FIG. 5 is a graph showing the relationship between the refractive index difference | n _o −n _p | between the liquid crystal and the polymer and the light transmittance (T _ON ) of the liquid crystal display element when an electric field is applied in this example. is there. From this graph, the following can be understood. Refractive index difference | n _o
When −n _p | ≦ 0.04, the transmittance T _ON becomes 1 or less, and the effect of increasing the contrast ratio CR (= T _OFF / T _ON ) is great. Meanwhile, the refractive index difference | n _o -n _p |>
In the case of 0.04, the transmittance T _ON becomes larger than 1, and the contrast ratio CR (= T _OFF / T _ON ) decreases. Therefore, in the present embodiment, the refractive index n _p of the polymer wall 17 is set between the ordinary refractive index n _o of the liquid crystal molecules 33 and the random state refractive index (n _o + n _e ) / 2 by the above mathematical expression 1. By defining as shown, the roughness on the display screen is eliminated, and the liquid crystal display element 11 with high display quality can be manufactured.

A modification of this embodiment will be described below.

(Photocurable resin) The polymer material used is, as the photocurable resin, for example, acrylic acid and acrylic acid ester having a long chain alkyl group of C3 or more, or a benzene ring, and more specifically, , Isobutyl acrylate, stearyl acrylate, lauryl acrylate,
Isoamyl acrylate, n-butyl methacrylate, n
-Lauryl methacrylate, tridecyl methacrylate, 2-ethylhexyl acrylate, n-stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-phenoxyethyl methacrylate, isobornyl acrylate, isobornyl methacrylate and further for increasing the physical strength of the polymer.
Functional or higher-functional resin, for example, bisphenol A dimethacrylate, bisphenol A diacrylate,
1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, neopentyl diacrylate, and more preferably, these monomers are halogenated. Especially chlorinated and fluorinated resins, eg 2.2.3.3.4.4-4
Hexafluorobutyl methacrylate, 2.2.3.4.
4.4-Hexachlorobutyl methacrylate, 2.2.
3.3-Tetrafluoropropyl acrylate, 2.2.
3.3-tetrafluoropropyl methacrylate, perfluorooctylethyl acrylate, perchlorooctylethyl methacrylate, perfluorooctylethyl acrylate, and perchlorooctylethyl methacrylate.

(Photopolymerization Inhibitor) In order to increase the shape of the liquid crystal droplets, it is preferable to add a compound that inhibits the polymerization reaction in addition to the above resin material. Specifically, a monomer that stabilizes radicals in a resonance system after radical generation,
And compounds. Specific examples include styrene, p-chlorostyrene, p-methylstyrene, p-phenylstyrene, 4-vinylnaphthalene, and nitrobenzene.

(Photopolymerization Initiator) As the photopolymerization initiator,
Common photoinitiators such as Irugacure 651, 184, 907, Darocure 1173, 1116, 2956 can be used. Also,
In order to improve the retention rate of liquid crystal droplets by the polymer wall, a sensitizer that can be polymerized with visible light may be used.

Further, the addition amount of these polymerization initiators is
It depends on the reactivity of each compound and is not particularly limited in the present invention, but it is preferably 5 to 0.01% with respect to the mixture of the liquid crystal and the photocurable resin (including the liquid crystalline photocurable resin). . When the amount of the photopolymerization initiator added to the mixture is 5% or more, the phase separation speed between the liquid crystal and the polymer film formed by the polymerization reaction is too fast, and the liquid crystal droplets are formed into a predetermined size. Will be difficult. This allows
Liquid crystal droplets become smaller. Therefore, the driving voltage is increased, the alignment control force of the alignment film on the substrate is weakened, and the liquid crystal region is reduced in the pixel. Further, when a photomask is used during the production of the liquid crystal drops, the liquid crystal drops are formed in the inter-pixel region of the liquid crystal display element corresponding to the light-shielding portion of the photomask, and the contrast is lowered. The amount of the photopolymerization initiator added is 0.0
If it is 1% or less, the photocurable resin cannot be sufficiently cured.

(Liquid Crystal Material) The liquid crystal material that can be used in the liquid crystal display device of the present invention is an organic mixture that exhibits a liquid crystal state at around room temperature, and is a nematic liquid crystal (liquid crystal for dual frequency drive, dielectric anisotropy Δε). <Including liquid crystal of <0), cholesteric liquid crystal (in particular, liquid crystal having selective reflection property for visible light), smectic liquid crystal, ferroelectric liquid crystal, discotic liquid crystal and the like. These liquid crystal materials may be mixed and used, and in particular, nematic liquid crystal or nematic liquid crystal to which a cholesteric liquid crystal (chiral agent) is added is preferable in terms of the characteristics of the liquid crystal display device.

More preferably, a liquid crystal excellent in chemical reaction resistance is preferable because it is accompanied by a photopolymerization reaction during processing. Specifically, ZLI-4801-000, ZLI-4801-
001 and ZLI-4792 (manufactured by Merck).

(Polymerizable Liquid Crystal Material) In the case of a mode of displaying by utilizing the orientation state of the substrate surface (F surrounded by polymer walls
LC, ECB, etc.), and photo-curing in a liquid crystal state (alignment state) are preferable. In order to give the mixture of the liquid crystal and the photo-curable resin a liquid crystal state, it is preferable to use a polymerizable liquid crystal material having both properties. In selecting a liquid crystal compound having a polymerizable functional group in the molecule from these liquid crystal materials, it is preferable that the portions expressing the liquid crystallinity are similar from the viewpoint of compatibility and similarity of refractive index. . In particular, an F or Cl liquid crystal material having a unique chemical environment is preferable. In addition, when using a ferroelectric liquid crystal, in order to create a stable smectic phase or when using a ferroelectric liquid crystal, the ferroelectric liquid crystal is used to create a stable smectic phase. It is preferable to use the polymerizable compound contained therein.

Although not particularly limited in the present invention, the compound having a liquid crystalline functional group in the molecule used in the present invention is a compound represented by the following chemical formula 1 or the like, which disturbs the liquid crystallinity of the liquid crystal molecule of the host. It is a difficult compound.

[0058]

A-B-LC A in Chemical Formula 1 represents a polymerizable functional group, and CH ₂ = CH-,
_{CH 2 = CH-COO-, CH} 2 = CH-COO-, or

[0059]

[Chemical 2]

A functional group having an unsaturated bond such as or a heterocyclic structure having a strain is shown. Moreover, B is a linking group connecting the polymerizable functional group and a liquid crystal compound, specifically an alkyl chain _{(- (CH 2) n -} ), an ester bond (-COO
-), an ether bond (-O-), a polyethylene glycol chain (-CH ₂ CH ₂ O-), and a linking group formed by combining these linking groups, to exhibit liquid crystallinity when mixed with the liquid crystal material Since it is preferable, a linking group having a length having 6 or more bonds from the polymerizable functional group to the rigid part of the liquid crystal molecule is particularly preferable.

LC in the above chemical formula 1 represents a liquid crystal compound, and is a compound represented by the following chemical formula 3 or a cholesterol ring and its derivative.

[0062]

Embedded image In the above Chemical Formula 3, G is a polar group that causes dielectric anisotropy of liquid crystal and the like, and is —CN, —OCH ₃ , —F, —Cl,
_{-OCF 3, -OCCl 3, -H,} -R: benzene ring having a functional group (R alkyl group), a cyclohexane ring, para-diphenyl ring, a phenyl cyclohexane ring. E is a functional group that connects D and G, and is a single bond, -C
_{H 2 -, - CH 2 CH} 2 -, - 0 -, - C≡C -, - CH
= CH- and the like. D is a functional group that binds to B in Chemical Formula 1, and is a part that influences the magnitude of dielectric anisotropy and refractive index anisotropy of liquid crystal molecules. , 1,10-diphenyl ring, 1,4-cyclohexane ring, 1,10-phenylcyclohexane ring and the like.

(Mixing ratio of liquid crystal and resin material) When the liquid crystal and the polymerizable compound are mixed, the weight ratio of both is 50:50 to.
97: 3 is preferable, and more preferably, the weight ratio of the both is 70:30 to 90:10. When the amount of the liquid crystal material is less than 50% by weight of the mixture of the liquid crystal and the polymerizable compound, the effect of the polymer wall becomes large, and the driving voltage necessary for driving the display of the liquid crystal display cell is remarkably increased and the practicality is lost. Further, when the liquid crystal material exceeds 93% by weight of the mixture, the physical strength of the polymer wall is lowered, the distance between the substrates is varied, and stable performance cannot be obtained in the liquid crystal display device.

Further, with respect to the polymerization ratio when the compound having liquid crystallinity and the non-liquid crystalline polymerizable compound are mixed within the above weight ratio range, the compound having liquid crystallinity may be 0.5%. . In particular, when a ferroelectric liquid crystal is used, by setting the compound having liquid crystallinity to 100%, two regions of a low molecular weight liquid crystal and a high molecular weight liquid crystal are generated, and the voltage is set to a voltage driven by each compound. As a result, it is possible to create a ferroelectric liquid crystal display capable of gradation display.

(Construction Method of UV (Ultraviolet) Illuminance Distribution) In order to maintain the shape of the liquid crystal droplets corresponding to the shape of the photomask,
It is important to construct the UV illuminance distribution for the mixture sandwiched between the pair of substrates. Specifically, regular UV using a photomask, microlens, interference plate, etc.
It is preferable to configure the distribution of illuminance. The position of the photomask may be inside or outside the liquid crystal display cell, and UV
It suffices if the light and shade can be created regularly.

When the photomask is separated from the liquid crystal cell, the optical image on the liquid crystal cell is blurred by the mask, liquid crystal droplets are not formed with high precision, and the effect of the present invention is reduced. Therefore, it is preferable that the photomask be as close as possible to the mixture of the liquid crystal and the photocurable resin. Further, it is desirable that the light from the UV light source be as parallel as possible. However, in order to improve the impact resistance of the ferroelectric liquid crystal display element, it is effective to dispose a small liquid crystal drop as a buffer around the liquid crystal drop of the same size as the picture element. Therefore, intentionally, in a photomask or the like, the translucent portion where the photomask material between the light-shielding portions is etched is blurred to make the translucency uneven, or the photomask is intentionally separated from the cell body, A light source with a slightly lower degree of parallelism of the emitted light may be used as the UV light source.

According to the examination results of the present inventors, it is preferable that the photomask has a size of uneven illuminance (a weak illuminance region including a light shielding region) of 30% or more of the area of the picture element. When a photomask having an uneven illuminance of less than 30% of the pixel area is used, the generated liquid crystal droplets also have an area of less than 30% of the pixel area. Therefore, the interface between the liquid crystal material and the polymer film is increased in the picture element, and the contrast is greatly reduced due to the scattering of light. More preferably, as the photomask, the interface between the liquid crystal material and the polymer film is extremely reduced in the picture element, and for example, one having a weak illuminance area larger than the area of the picture element is preferable. It is preferable to use a photomask or the like in which only the above portion is irradiated with UV light.

Further, in the liquid crystal display element of the mode that does not use scattering between the polymer film and the liquid crystal material, the shape of the weak illuminance area formed by the light shielding area such as a photomask is
Any material may be used as long as it covers 30% or more of the picture element and locally reduces the UV light intensity. In the present invention, the shape is not particularly limited, but a circle, a rectangle, a trapezoid, a rectangle, a hexagon, a rhombus, a character, a figure separated by a curve and a straight line,
Also, shapes such as a part of these figures cut, a figure combining these figures, and an aggregate of these small figures are possible. More preferably, a photomask or the like in which the pixel portion of the liquid crystal display element is a weak illuminance region is preferable in that the light scattering intensity in the pixel is reduced and the contrast of the liquid crystal display element is improved.

In practicing the present invention, one or more of these figures may be selected and used. Preferably, in order to improve the uniformity of liquid crystal droplets, the shape should be as small as possible.
It is preferable to limit the number to the seeds and arrange them.

The cell prepared by the above method is combined with a polarizing plate or the like to obtain the FL which is a conventional display system.
It is possible to create a liquid phase display device in which C (SSF), ECB system, etc. are confined in a polymer wall or partially partitioned, and a large screen and film (in addition to glass as a substrate material, The film can also be used) and so on.

(Alignment control power) When a mixture of liquid crystal molecules and a photopolymerizable resin is irradiated with light having a light and shade, a thin polymer film may remain on the surface of the substrate even in the liquid crystal region, The alignment control force of the alignment film on the substrate may be reduced. Further, when regularly controlling the phase separation between the liquid crystal and the resin by using a photomask, specifically, the liquid crystal domains in the liquid crystal region have a structure in which they are radially or randomly aligned, and when the voltage is applied, the liquid crystal molecules Since the rising direction is almost omnidirectional, the viewing angle characteristic is improved. That is, when a voltage is applied, the interaction between the liquid crystal molecules and the polymer material causes the liquid crystal molecules to tilt in each direction with respect to the polymer wall that surrounds the liquid crystal droplets. At the positions of A and arrow B, the states are almost the same, and the viewing angle characteristic is improved.

When a vertical alignment film having a high alignment control force is used, the liquid crystal molecules are homeotropically aligned vertically to the substrate. In this case, due to the interaction between the liquid crystal molecule and the polymer material when a voltage is applied, the rising direction of the liquid crystal molecule is in the lateral direction of each wall, and the refractive index is almost the same when viewed from any direction. It will be improved.

It was confirmed that when a material having a high liquid crystal alignment ability such as a ferroelectric liquid crystal is used, the alignment is performed according to the alignment control force of the substrate even in the case of the present invention in which the alignment control force is weakened.

(Driving method) The produced liquid crystal display cell is
Simple matrix drive, TFT (thin film transistor),
It can be driven by a driving method such as active driving using a switching element such as MIM (metal-insulating film-metal transistor). In the present invention, the driving method of the liquid crystal display element is not particularly limited.

[0075]

According to the present invention, it is possible to provide a liquid crystal display element surrounded by a polymer wall, which has a high display quality and is not rough on the display screen. That, combined to optimize the liquid crystal material polymerizable resin composition, the refractive index n _p is the liquid crystal of the ordinary refractive index n _o of the polymerizable resin composition, with respect to the extraordinary refractive index n _e, n _o -0.04 ≤n _p ≤ (n _e +
The polymerizable resin composition is selected so as to satisfy the range of n _o ) / 2. As a result, the difference in refractive index between the liquid crystal layer and the polymer wall can be reduced, the roughness on the display screen of the conventional liquid crystal display element can be eliminated, and a liquid crystal display element with high display quality can be manufactured.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display element 11 according to an embodiment of the present invention.

FIG. 2 is a plan view of a photomask 25 used in this embodiment.

3 is a plan view of a picture element region of the liquid crystal display element 11. FIG.

FIG. 4 is a diagram illustrating a range of a refractive index in this example.

FIG. 5 is a graph showing the relationship between the refractive index of the liquid crystal and the polymer and the light transmittance of the liquid crystal display element when an electric field is applied in this example.

FIG. 6 is a sectional view of a conventional liquid crystal display element 1.

[Explanation of symbols]

 11 liquid crystal display element 12, 13 glass substrate 14 liquid crystal layer 15 picture element electrode 16 common electrode 17 polymer wall 19 picture element 33 liquid crystal molecule

Claims (6)

[Claims] 1. A liquid crystal layer is sandwiched between a pair of substrates, at least one of which is translucent, and a plurality of picture elements formed including the liquid crystal layer are arranged in a matrix and each picture element is arranged. Has a liquid crystal region surrounded by a polymer film, and the refractive index (n _p ) of the polymer is the ordinary light refractive index (n _o ) and the extraordinary light refractive index (n _e ) of the liquid crystal composition, n _o -0.04 ≦ n _p ≦
A liquid crystal display device defined to be (n _e + n _o ) / 2. 2. The liquid crystal display according to claim 1, wherein at least one or more liquid crystal domains are present in the one picture element, and the coordination of each liquid crystal domain is at least either random or radial. element. 3. The liquid crystal display element according to claim 1, further comprising insulating films for orienting liquid crystal molecules on surfaces of the respective substrates which face each other. 4. The liquid crystal display element according to claim 1, further comprising a polarizing plate on at least one of the pair of substrates. 5. A liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates, at least one of which is transparent, and a plurality of picture elements formed including the liquid crystal layer are arranged in a matrix. A method for producing, comprising: a photopolymerizable resin, a photopolymerization initiator, and a refractive index (n _p ) of a polymer film in a composite film including a polymer film obtained by curing the photopolymerizable resin and a liquid crystal layer. but ordinary refractive index of the liquid crystal layer (n _o), with respect to the extraordinary refractive index _{(n e), n o -0.04} ≦ n p ≦ (n e
To the mixture containing the liquid crystal compound set to + n _o ) / 2,
A method for producing a liquid crystal display device, wherein a polymer and a liquid crystal material are regularly distributed between the substrates by causing phase separation accompanying a polymerization reaction by light having a regular irradiation intensity unevenness. 6. The method of manufacturing a liquid crystal display device according to claim 5, wherein a light-shielding portion that substantially weakens the intensity of the irradiated light is provided in the pixel, and then the mixture is irradiated with light.