JPH0784244A - Liquid crystal display element and its production - Google Patents

Abstract

PURPOSE:To improve brightness of an image and display quality by arranging plural pixels formed as containing a liquid crystal layer in a matrix state and forming several projections on the electrode in each pixel. CONSTITUTION:A TN liquid crystal display element 11 has a liquid crystal layer 14 between a pair of glass substrates 12, 13. Plural pixel electrodes 15 are formed in a matrix on the one substrate 12, while the substrate 13 has a common electrode 16. Polymer films 17, 18 are formed on the substrates 12, 13, respectively. Each pixel 19 consists of the picture element electrode 15, common electrode 16, and liquid crystal layer 14 interposed between the picture element electrode 15 and the common electrode 16. Further, the polymer films 17, 18 in each pixel 19 have projections formed almost in the center of the picture element and a projected part substantially continuous along the edge of the pixel. Several projections radially or rather randomly arranged are formed from the center projection to the peripheral projected part.

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
urperTwisted 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, as a display element utilizing the electro-optical effect, a TN type or STN type display element using nematic liquid crystal has been put into practical use. A display element using a ferroelectric liquid crystal has also been proposed. These display elements require a polarizing plate and an alignment treatment. On the other hand, as a display element that does not require a polarizing plate and utilizes liquid crystal scattering for display, there is a display element that uses a dynamic scattering (DS) effect and a phase transition (PC) effect. Recently, as a display element that does not require a polarizing plate and does not require an alignment treatment, a display method has been proposed in which the transparent or cloudy state is electrically controlled by utilizing the birefringence of liquid crystal. This display method basically matches the ordinary refractive index of liquid crystal molecules with the refractive index of the supporting medium,
When a voltage is applied and the liquid crystal is aligned, the transparent state is displayed, and when no voltage is applied, the light scattering state due to the disorder of the alignment of the liquid crystal molecules is displayed.

[0003]

As the above-mentioned method proposed, a liquid crystal and a light- or thermosetting resin are mixed in JP-B No. 61-502128, and the resin is cured to form a space between a pair of substrates. A method of depositing liquid crystals to form liquid crystal droplets in a resin is disclosed. Japanese Patent Application Laid-Open No. 4-338923 discloses an element that improves the viewing angle by using a polarizing plate.
JP-A-4-212928 discloses a display element in which the polymer dispersion type liquid crystal element is sandwiched between orthogonal polarizing plates. The display element has a large effect of improving the viewing angle characteristics, but since the depolarization due to scattering is utilized in principle, the brightness of the image is about 1/2 of that of the TN mode liquid crystal display element. However, there is a problem that the image is dark. Therefore, the utility value is low. Further, Japanese Patent Laid-Open No. 27242/1993 discloses a method in which the alignment state of liquid crystal is disturbed by polymer walls and protrusions to form random domains to improve the viewing angle.
However, this method has a problem that the contrast is low and the display quality is low since the domains are random and the polymer material also enters the pixel portion.

A conventional liquid crystal display device using a polarizing plate has poor viewing angle characteristics and is unsuitable for a liquid crystal display device viewed at a large viewing angle. FIG. 6 is a 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 are
The structure is such that the initial alignment is twisted by 90 ° and the liquid crystal molecules stand up at an angle (pretilt angle) in one direction. Therefore, when the drive voltage is applied from the power source 6, as shown in FIG. 6C, the alignment process is performed so that the liquid crystal molecules 5 rise in the same direction.
Therefore, when the liquid crystal molecule 5 rises during the halftone display, the liquid crystal molecule 5 tilts in the same direction as shown in FIG. 6B. 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 a relatively wide angle with each other as shown in the figure, the apparent refractive indexes are different. Thereby, the respective directions A and B
The contrast of the image as seen from above differs greatly, and in an extreme case, a display abnormality such as an image inversion phenomenon occurs. As described above, in the conventional display mode, poor viewing angle characteristics pose a problem.

As shown in FIG. 7, a liquid crystal display element 1a having a polarizing plate, which regularly causes phase separation of a liquid crystal and a polymer material by using a photomask, is provided between the substrates 2 and 3. And a liquid crystal droplet 9 surrounded by the polymer wall 7 is formed. In the liquid crystal droplet 9, the liquid crystal molecule 5 rises in the direction of each wall 7 due to the interaction between the liquid crystal molecule 5 and the polymer wall 7 when a voltage is applied. Therefore, the apparent refractive index of the liquid crystal molecules 5 viewed from the respective directions of the arrow A and the arrow B becomes substantially the same, which is a great effect in improving the viewing angle characteristics. On the other hand, since the polymer wall 7 that connects the pair of substrates 2 and 3 is present, the interaction between the liquid crystal molecules 5 and the polymer wall 7 is large. As a result, there is a problem that the response speed of the liquid crystal molecules 55 is slow and the hysteresis characteristic regarding the state change of the liquid crystal molecules 5 is deteriorated.

The present invention has been made in order to solve the above problems, and provides a liquid crystal display device capable of improving the brightness of an image and significantly improving the display quality, and the manufacturing method is simplified. It is an object of the present invention to provide a method for manufacturing a liquid crystal display device that can be realized.

[0007]

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 elements are arranged in a matrix, and a plurality of protrusions are provided on the electrodes in one picture element, whereby the above object can be achieved.

In the present invention, the plurality of protrusions may be regularly arranged for each of the picture elements, and may be formed radially or randomly within the one picture element.

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

According to the method for producing a liquid crystal display device of the present invention, a mixture containing a liquid crystal compound, a photocurable resin and a photopolymerization initiator is provided between a pair of substrates, at least one of which is translucent, at a regular irradiation intensity. A step of causing a phase separation in the mixture due to the polymerization reaction of the photocurable resin by the light having unevenness, and regularly distributing the polymer part and the liquid crystal material on the horizontal plane between the pair of substrates. Including, by which, the above-mentioned object can be achieved.

In the present invention, the resin content of the mixture of the liquid crystal material and the photocurable resin is 10% by weight to 0.1% by weight.
May be.

[0012]

In order to solve the above problems, the present inventors have
In a liquid crystal display device having a liquid crystal region surrounded by a polymer, attention is paid to a horizontal portion where liquid crystal domains are radially or randomly arranged in the liquid crystal region to reduce the formation of polymer walls and reduce the liquid crystal domain. It has been found that they can be arranged radially or randomly. Hereinafter, the present invention will be described in more detail.

In the present invention, a mixture of a liquid crystal material, a photocurable resin and a photopolymerization initiator is photocurable by light having a weak illuminance region having an area approximately corresponding to each picture element of the liquid crystal display element. Light cure the resin. The present invention, by reducing the addition amount of the photocurable resin, during the photocuring, between the upper and lower substrates of a liquid crystal cell composed of a pair of substrates and a liquid crystal layer sandwiched between the pair of substrates, The liquid crystal display device is a method for manufacturing a liquid crystal display device, in which a liquid crystal display device is produced without forming a polymer wall made of a polymer material.

At this time, in the mixture between the pair of substrates, the photocurable resin causes a polymerization reaction in the light irradiation region. This reduces the concentration of unreacted resin in the mixture in the irradiated area. Mass transfer is performed according to the concentration gradient in the mixture. During the movement of the mixture, a partial polymerization reaction occurs due to scattered light and reflected light. Therefore, the alignment film is formed on the pair of substrates while the mass transfer is performed from the center of the pixel toward the irradiation region in the peripheral portion of the pixel.

In the present invention, the liquid crystal molecules are randomly or radially aligned. Therefore, it is possible to prevent the liquid crystal molecules from being aligned in one direction when a voltage is applied, unlike the conventional TN type liquid crystal cell. In particular, when performing a halftone display, since the apparent refractive index is substantially uniform in all directions in which the liquid crystal display device of the present invention is viewed, the viewing angle characteristics of the liquid crystal cell are significantly improved.

Further, in the liquid crystal display device of the present invention, since the polymer wall extending between the pair of substrates is not formed, the amount of interaction between the liquid crystal and the polymer material can be reduced. As a result, the response speed of the liquid crystal molecules can be increased and the hysteresis characteristic can be improved.

(Photocurable Resin) The polymer material used is a photocurable resin. Examples of the photocurable resin include acrylic acid and acrylate 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 a polyfunctional resin having two or more functional groups, such as R, to increase the physical strength of the polymer.
-684 (Nippon Kayaku Co., Ltd.), 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 such as 2.2.3.4.4.4-hexafluorobutylmethacrylate, 2.2.3.4.4.4-.
Hexachlorobutyl methacrylate, 2.2.3.3-
Tetrafluoropropyl methacrylate, 2.2.3.
3. -Tetrafluoropropyl methacrylate, perfluorooctylethyl methacrylate, perchlorooctylethyl methacrylate, perfluorooctylethyl acrylate, perchlorooctylethyl acrylate.

(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, it is a monomer or compound that stabilizes a radical in a resonance system after radical generation, and specifically, styrene, p-chlorostyrene, p-methylstyrene, p-phenylstyrene, nitrobenzene, etc. Is.

(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 the liquid crystal droplets by the polymer wall, a sensitizer that can be polymerized with visible light may be used.

When a plastic substrate having an absorption characteristic in the ultraviolet wavelength range is used, Lucirin TPO (manufactured by BASF) having the absorption characteristic in the ultraviolet wavelength range, KAYACURE
DETX-S (manufactured by Nippon Kayaku Co., Ltd.), CGI369 (manufactured by Ciba Geigy), etc. can be used.

Further, the addition amount of these photopolymerization initiators depends on the reactivity of each compound and is not particularly limited in the present invention, but the liquid crystal and the photocurable resin (including the liquid crystal photocurable resin). It is preferably 5 to 0.01% with respect to the mixture with. 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. As a result, the liquid crystal droplet becomes 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,
If it is 0.01% 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 near room temperature, and is a nematic liquid crystal (liquid crystal for dual frequency drive,
Included are liquid crystals having a dielectric anisotropy Δε <0), cholesteric liquid crystals (particularly liquid crystals having selective reflection characteristics for visible light), smectic liquid crystals, ferroelectric liquid crystals, and discotic liquid crystals. 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, it is a liquid crystal having a functional group such as a fluorine atom in the compound. Specifically, ZLI-4801, ZLI-48
01-001, ZLI-4792 (manufactured by Merck) and the like.

(Polymerizable Liquid Crystal Material) In the case of a liquid crystal display element of a display mode such as an FLC mode or an ECB mode in which liquid crystal droplets are surrounded by a polymer wall and the orientation state of the substrate surface is used for display, the liquid crystal state (orientation It is preferable that it is photocured in a state. In order to give the mixture of the liquid crystal and the photocurable resin a liquid crystal state, it is preferable to use a polymerizable liquid crystal material having both properties. In selecting these liquid crystal materials and liquid crystal compounds such as the above polymerizable liquid crystal materials having a polymerizable functional group in the molecule, the fact that the respective portions expressing the liquid crystallinity are similar means that the compatibility is high. It is preferable from the viewpoint. In particular, regarding the F and Cl liquid crystal materials having a unique chemical environment, the liquid crystal compound having a polymerizable functional group is also preferably the F and Cl liquid crystal materials. Also in the case of using a ferroelectric liquid crystal, it is preferable to use a polymerizable compound having a ferroelectric liquid crystal in its molecule in order to form a stable smectic phase.

Although not particularly limited in the present invention, the compound having a liquid crystalline functional group in the molecule used in the present invention, that is, the polymerizable liquid crystal material is a compound represented by the following chemical formula 1, A compound that does not disturb the liquid crystallinity of the liquid crystal molecules of the host.

[0026]

Embedded image A-B-LC A in the above Chemical Formula 1 represents a polymerizable functional group, and CH ₂ ═CH
_{-, CH 2 = CH-COO-} , CH 2 = CH-COO-,
A functional group having an unsaturated bond such as CH ₂ —CH— or a heterocyclic structure having strain is shown.

B is a connecting group connecting the polymerizable functional group and the liquid crystal compound, and specifically, an alkyl chain (-(C
H ₂₎ n-), an ester bond (-COO-), ether bond (-O-), a polyethylene glycol chain (-CH ₂
CH ₂ O-), and a linking group formed by combining these linking groups. When the polymerizable liquid crystal material and the liquid crystal material are mixed, it is preferable that the mixture exhibits liquid crystallinity, so that the mixture has a length having 6 or more bonds from the polymerizable functional group to the rigid part of the liquid crystal molecule. Linking groups are particularly preferred.

LC in the above chemical formula 1 represents a liquid crystal compound, and is a compound represented by the following chemical formula 2 or a cholesterol ring and its derivative.

[0029]

Embedded image In the above Chemical Formula 2, 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,-
_{CH 2 -, - CH 2 CH} 2 -, - O -, - C≡C -, - C
H = 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. Specifically, it is a paraphenyl ring, a 1,10-diphenyl ring, a 1,4-cyclohexane ring, a 1,10-phenylcyclohexane ring or the like.

(Mixing ratio of liquid crystal and polymerizable compound) When the liquid crystal and the polymerizable compound are mixed, the weight ratio of both is preferably such that the content of the polymerizable compound is 10 to 0.1% by weight. . When the content of the polymerizable compound exceeds 10% by weight,
As described in the prior art, the polymer wall is formed between the pair of substrates, which increases the interaction between the liquid crystal and the polymer material,
Hysteresis characteristics and liquid crystal response speed deteriorate. on the other hand,
When the content of the polymerizable compound is less than 0.1% by weight, the polymer film for aligning the liquid crystal molecules, that is, the alignment film is not sufficiently formed on the substrate. Therefore, the alignment control force of the alignment film on the liquid crystal is reduced. The content of the polymerizable compound is more preferably 7 to 1% by weight.

(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, it is preferable to form a regular UV illuminance distribution for the mixture by using a photomask, a microlens, an interference plate, or the like. The position of the photomask may be either inside or outside the liquid crystal cell as long as it can regularly create a shade in UV light.

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 results of examination by the present inventors, the size of uneven illuminance as a photomask (a weak illuminance region including a light shielding region)
Is preferably 30% or more of the area of the picture element. If a photomask having an uneven illuminance of less than 30% of the area of the picture element is used, the alignment control force becomes weaker for each picture element, and the display uniformity is impaired. Therefore, a photomask having a weak illuminance area larger than the area of the picture element is preferable, and a photomask or the like in which only the portion other than the picture element is irradiated with UV light is preferable.

Further, in the liquid crystal display element of the mode which does not use the 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.

Further, in carrying out the present invention, one or more kinds of these figures may be selected and used. Preferably, in order to improve the uniformity of the liquid crystal droplets, the shape should be limited to one kind as much as possible. Is preferred.

A feature of the present invention is that the liquid crystal droplets are regularly arranged in a direction parallel to the substrate, that is, they are arranged according to the arrangement state of the picture elements. Specifically, the arrangement of the weak illuminance region in the liquid crystal display element becomes a problem. With respect to the arrangement of the weak illuminance areas, it is preferable to match the pitch of the picture elements, and it is preferable to arrange one weak illuminance area in one picture element.

The weak illuminance areas may be arranged over several picture elements, and the weak illuminance areas may be arranged for each column or row of a plurality of picture elements arranged in a matrix, or may be arranged adjacent to each other. The entire weak illuminance region of the liquid crystal display element may be arranged for each set of picture elements.

A polarization microscope was used to measure the shape of the liquid crystal droplets. The liquid crystal cell was peeled off between the two substrates, the liquid crystal molecules were removed with a solvent, and the local portion of the polymer matrix, which was the polymer film remaining on the substrates, was removed. The specific shape was measured. The observation of the polymer matrix was performed by selecting 20 liquid crystal droplet regions having the most regularity in the sample, because there is a portion where the structure is destroyed during sample preparation. The photomask is required to have the same regularity as the regularity of the arrangement of the weak illuminance region of the liquid crystal display element. In addition, the weak illuminance regions do not need to be independent of each other, and may be connected to adjacent weak illuminance regions at the peripheral edge thereof.
It suffices if the region that effectively blocks V light has the above-described shape and arrangement.

The liquid crystal cell produced by the above method and having the above configuration is combined with a polarizing plate or the like to obtain FLC (SSF (Surface Stab) which is an example of the conventional display system.
ilized Ferroelectric)), an ECB method, or the like in which a liquid crystal material is confined in a polymer wall, or a liquid crystal layer is partially partitioned. This makes it possible to increase the screen size and film of the liquid crystal display element. In particular, when a liquid crystal display element is formed into a film, a film can be used as a substrate material in addition to glass.

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

[0041]

EXAMPLES Examples of the present invention will be shown below.
It is not limited to this. (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, the TN type liquid crystal display element 11 has a liquid crystal layer 1 between a pair of glass substrates 12 and 13.
4 is sandwiched between them. 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. Each board 1
Polymer films 17 and 18 are formed on the films 2 and 13, respectively. The shapes of the polymer films 17 and 18 will be described later. The picture element electrode 15, the common electrode 16 and the picture element electrode 15
Each picture element 19 is configured to include the liquid crystal layer 14 sandwiched between the picture element 19 and the common electrode 16.

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

A pair of glass substrates (plate thickness 1.1 mm) 1
A pair of display substrates 20 and 21 having ITO (a mixture of indium oxide and tin oxide, film thickness 50 nm) as transparent electrodes for the pixel electrode 15 and the common electrode 16, respectively, are spherical and cylindrical on 2 and 13 respectively. Alternatively, a cell was formed by keeping the cell thickness with a 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.

The photomask 25 shown in FIG. 2 is arranged on the cell upper surface on the cell thus prepared. This photomask 2
In FIG. 5, 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 portion is formed at the center of each light-shielding region 22 as an example. The light transmission holes 24 are formed respectively.

Further, in the cell, a photocurable resin material (for example, R-684 (manufactured by Nippon Kayaku Co.): styrene:
Isobornyl methacrylate = 10: 5: 85) 0.1
g, a liquid crystal material, for example, ZLI-4792 (manufactured by Merck & Co., Inc .: S-811 0.4 wt% content) 1.9 g, and a photopolymerization initiator, for example, 0.0025 of Irugacure 651.
A mixture was prepared by mixing with g. Specifically, the mixture was poured into a cell in a transparent state (35 ° C.), and then the same temperature was maintained to obtain parallel rays from the dot pattern side of the photomask 25 at 10 mW under a high-pressure mercury lamp.
At the position of / cm ² , 20 cycles of irradiation cycle (1 second UV light irradiation, 30 second irradiation not performed) were performed. afterwards,
UV light was irradiated for 10 minutes, and further, the photomask 25 was removed for 10 minutes, and UV light was irradiated to cure the photocurable resin material in the mixture.

When the liquid crystal display element 11 in which the liquid crystal layer 14 was formed between the pair of display substrates 20 and 21 of the cell was observed with a polarization microscope in this manner, the display substrates 20 and 21 above and below were partially formed. Although there is a region in which a polymer wall formed by curing the photocurable resin material is formed, the liquid crystal display element 11 as a whole is, as shown in FIG. The structure was such that the polymer wall was not formed. Moreover, as shown in FIGS. 3 and 4, the liquid crystal domains were partially radially formed.

The configuration of each picture element of the liquid crystal display element 11 will be described in detail below. 3 is a plan view of a part of the liquid crystal display element 11, FIG. 4 (1) is a sectional view taken along the section line AA of FIG. 3, and FIG. It is sectional drawing seen from the surface line BB. Each picture element 19 is formed in a range substantially covering the picture element electrode 15. Further, the projections 26 are formed on the polymer films 17 and 18 within the range of each picture element 19 substantially at the center of each picture element 19, and at the periphery of each picture element 19, the peripheral edge is formed. A ridge 27 having ridges that are substantially continuous is formed along the portion. Further, the protrusion 26
A plurality of radial ridges 28 having a radial or relatively random shape are formed between the ridges 27 to 27. A relatively thin film portion 29 is formed on the electrodes 15 and 16 between the protrusions 26, the protrusions 27 and the radial protrusions 28. The thin film portion 29 serves as an alignment film for the liquid crystal molecules of the liquid crystal layer 14.

Further, in the liquid crystal layer 14 within the range of the picture element 19, the liquid crystal domains 30 are respectively formed in the portions corresponding to the thin film portion 29, and the projections 26, the protrusions 27 and the radial protrusions 28 are formed. Disclinations 31 are formed in corresponding portions in a radial or random shape corresponding to these shapes.

Before and after the prepared liquid crystal display element 11, two polarizing plates whose polarization axes are orthogonal to each other are bonded respectively, and the liquid crystal display element 11 in which the liquid crystal layer 14 is sandwiched between the polymer films 17 and 18 is formed. Created. The electro-optical characteristics of the produced liquid crystal display element 11 are shown in Table 1 below. In Table 1, in the item of reversal phenomenon in the halftone, ◯: a state where the reversal phenomenon does not occur, ×: a state where the reversal phenomenon can be easily observed
Mark: Shows a state where the reversal phenomenon is barely observed.

Comparative Example 1 In the cell used in Example 1, 0.15 g of a photocurable resin (R-684 (manufactured by Nippon Kayaku): styrene: isobornyl methacrylate = 10: 5: 85) was added. And 0.85 g of a liquid crystal material ZLI-4792 (manufactured by Merck: S-811 0.4% by weight),
The mixture was injected with 0.0025 g of the photoinitiator Irugacure 651. Then, as in the first embodiment,
A liquid crystal display device in which the liquid crystal layer 14 was sandwiched between the polymer films 17 and 18 was prepared. The characteristics are shown in Table 1 below.

Comparative Example 2 A liquid crystal was prepared by using a mixture of 0.001 g of a photo-curing resin, 1.2 g of a liquid crystal material and 0.0025 g of a photopolymerization initiator Irugacure 651 in the above cell. A display element was created.

In Table 1 below, the hysteresis is the difference between the voltage values of the driving voltage to the liquid crystal layer 14 at the time of increasing and decreasing the driving voltage at which the transmittance change becomes 50% in the transmittance curve. Define in.

The light transmittance was measured as 100% when the two polarizing plates were aligned so that the polarization axes were parallel to each other.

[0054]

[Table 1]

FIG. 5 is a sectional view of the liquid crystal display element 11 of this embodiment. For example, in the TN type liquid crystal display element 11,
In the picture element 19, the liquid crystal molecules 14a of the liquid crystal layer 14 are radially or randomly aligned as described above.
Therefore, when the drive voltage is applied from the power source 32, the liquid crystal molecules 14a rise along the protrusions 27 in the alignment state as shown in FIG. 5C. Therefore, when the liquid crystal molecules 14a rise during the halftone display, as shown in FIG. 5B, the liquid crystal molecules 14a are radially or randomly arranged with respect to the center of the picture element 19.
Tilts. For this reason, as shown in the figure, when the liquid crystal molecules 14a are viewed from the respective directions indicated by arrow A and arrow B having relatively wide angles with each other, the apparent refractive index is made uniform. It will be. As a result, the contrasts of the images viewed from the respective directions A and B are made uniform, display abnormalities such as the image inversion phenomenon described in the related art can be prevented, and the viewing angle characteristics are significantly improved. can do.

As described above, in the present embodiment, the liquid crystal display element is mixed with the mixture of the liquid crystal material, the photocurable resin and the photopolymerization initiator between the pair of display substrates 20 and 21 of the liquid crystal display element 11. The photo-curable resin was cured by light having a weak illuminance region having an area substantially corresponding to each of the picture elements 19 of 11. At this time, in the present embodiment, by reducing the addition amount of the photocurable resin in the mixture to be smaller than the addition amount in the prior art, at the time of photocuring, the display substrates 20 above and below the liquid crystal display cell, The liquid crystal display element 1 is formed without forming a polymer wall made of a polymer material between the two.
1 can be created.

At this time, the pair of display substrates 20 and 21
In the mixture in the middle, the photocurable resin causes a polymerization reaction in the light irradiation region. This reduces the concentration of unreacted resin in the mixture in the irradiated area. Mass transfer is performed according to the concentration gradient in the mixture. During the movement of the mixture, a partial polymerization reaction occurs due to scattered light and reflected light. Therefore, the polymer films 17 and 18 are formed on the pair of substrates 20 and 21 while mass transfer is performed from the center of the picture element 19 toward the irradiation area in the peripheral portion of the picture element 19.

In the liquid crystal layer 14 of the picture element 19 of the liquid crystal display element 11 of this embodiment, the liquid crystal molecules 14a are randomly or radially oriented. Therefore, it is possible to prevent the liquid crystal molecules from being aligned in one direction when a voltage is applied, unlike the conventional TN type liquid crystal cell. In particular, when performing a halftone display, since the apparent refractive index is substantially uniform in all directions in which the liquid crystal display device of the present invention is viewed, the viewing angle characteristics of the liquid crystal cell are significantly improved.

Further, in the liquid crystal display device 11 of the present embodiment, since the polymer wall extending between the pair of substrates 20 and 21 is not formed, the interaction between the liquid crystal molecules 14a and the polymer material can be prevented. The amount can be reduced. As a result, the response speed of the liquid crystal molecules 14a can be increased and the hysteresis characteristic can be improved.

In this way, the liquid crystal display element 1 of this embodiment
In No. 1, the brightness of the image can be improved, and the display quality is remarkably improved. Further, the manufacturing method can be simplified.

Specifically, the liquid crystal display device of the present invention can be used for a flat display utilizing a wide viewing angle, for example, a personal computer, a word processor, an amusement machine and a television receiver, and has a shutter effect. It can be used for various display boards, windows, walls, etc.

Further, the liquid crystal display element of this embodiment has a characteristic that it is strong against external pressure because there are micro liquid crystal cells surrounded by a large number of polymer walls in the cell. Therefore,
It can be used as a liquid crystal display element for a pen input device.

[0063]

INDUSTRIAL APPLICABILITY The present invention is an invention relating to an element having an alignment film capable of aligning liquid crystal molecules in multiple directions within one picture element. Since the liquid crystal molecules are oriented in all directions, a conventional liquid crystal display element is provided. It is possible to improve the drastic change in contrast depending on the viewing angle direction, and to improve the hysteresis that is probably caused by the polymer wall because the polymer wall is not substantially formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a TN type 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.

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

FIG. 4 is a cross-sectional view taken along section line AA and section line BB of FIG.

FIG. 5 is a cross-sectional view illustrating the operation of the liquid crystal display element 11 of this example.

FIG. 6 is a cross-sectional view of a conventional TN type liquid crystal display element 1.

FIG. 7 is a cross-sectional view of another conventional liquid crystal display device.

[Explanation of symbols]

 11 liquid crystal display element 12, 13 glass substrate 14 liquid crystal layer 14a liquid crystal molecule 15 picture element electrode 16 common electrode 17, 18 polymer film 19 picture element

Claims (5)

[Claims] 1. 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 to form one picture element. Liquid crystal display device having a plurality of protrusions on electrodes inside thereof 2. The liquid crystal display device according to claim 1, wherein the plurality of protrusions are regularly arranged for each of the picture elements, and are radially or randomly formed in the one picture element. 3. The liquid crystal display element according to claim 1, wherein a polarizing plate is mounted on at least one of the pair of substrates. 4. A mixture containing a liquid crystal compound, a photocurable resin, and a photopolymerization initiator between a pair of substrates, at least one of which is translucent, is exposed to the mixture by light having a regular irradiation intensity unevenness. A method for producing a liquid crystal display device, wherein phase separation is generated due to a polymerization reaction of a photocurable resin, and a polymer portion and a liquid crystal material are regularly distributed on a horizontal plane between the pair of substrates. 5. The method for producing a liquid crystal display device according to claim 4, wherein the resin content of the mixture of the liquid crystal material and the photocurable resin is 10% by weight to 0.1% by weight.