JP2778516B2 - Liquid crystal display device and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device for displaying characters, figures and the like, and a method for manufacturing the same.
It is used as a liquid crystal display device having excellent image quality and viewing angle characteristics.

[0002]

2. Description of the Related Art A conventional liquid crystal display device has an inherent problem that a viewing angle is narrow due to a characteristic behavior of liquid crystal molecules when a voltage is applied. The reason why the viewing angle of a liquid crystal display device is narrow will be described with reference to a twisted nematic (TN) mode which is often used in a liquid crystal display device driven by a thin film transistor (TFT) (FIG. 2).

[0003] Liquid crystal molecules are considered to be rod-like molecules.
In the N mode, as shown in FIG. 2, liquid crystal molecules are sandwiched between two glass substrates. That is, the liquid crystal molecules 2
Is oriented substantially parallel to the glass substrate in both the upper substrate 3 and the lower substrate 4 (however, it is oriented at a small pretilt angle 11 with the glass substrate interface). Actually, the liquid crystal molecules are arranged so that the azimuthal direction in the upper substrate surface and the azimuthal direction in the lower substrate surface are substantially 90 °. In FIG. Is not shown. In this state where no voltage is applied, there is no noticeable viewing angle dependency.

When a voltage is applied to the TN arrangement, the arrangement of the liquid crystal molecules is changed so as to be parallel to the electric field as shown in FIG. At this time, the liquid crystal molecules tend to rise from the pretilt angle direction (in FIG. 3, the twist of the liquid crystal molecules is omitted as in FIG. 2). The birefringence of liquid crystal molecules is determined by the angle between the long axis of the liquid crystal molecules and the light beam. Looking at the liquid crystal molecules at the center of the cell in FIG. 3, the light rays 13 make a large angle with the long axis of the liquid crystal molecules at the cell center, while the light rays 12 make a small angle. For this reason, the line of sight change to the left and the line of sight to the right in FIG. 3 show different optical characteristics. In a normal liquid crystal display device, the horizontal direction in FIG. 3 is set to the vertical direction of the screen. For this reason, a change in the viewing angle in either the upper or lower direction is recognized as image inversion in which the negative / positive is inverted. Further, with respect to a change in the line of sight in another direction, the image is recognized as whitening, in which the image becomes whitish and the contrast is reduced.

[0005] A liquid crystal display device for solving this problem is disclosed in Japanese Patent Application Laid-Open No. 4-149410. FIG. 4 shows the configuration of the liquid crystal display device disclosed in the publication (the liquid crystal molecules are not shown twisted for easy viewing). Compared to FIG. 2, in the liquid crystal alignment structure in FIG. 4, the pretilt angle directions on the glass substrate interface do not match for the upper and lower substrates. The liquid crystal having this alignment structure is said to have “splay distortion” because the pretilt angle direction is in a mismatched relationship. At this time, the angle of the liquid crystal molecules at the center of the cell cross section is almost 0 ° with respect to the substrate. In this liquid crystal display device, the common electrode 8 is formed continuously on the entire surface of the upper substrate, and the pixel electrode 6 is formed so as to have a fixed section on the lower substrate.

When a voltage is applied to the liquid crystal display device, an electric field disturbance occurs at the edge of the pixel electrode as shown in FIG. 5 because the areas of the common electrode 5 and the pixel electrode 6 are different. As shown in FIG. 5, in the liquid crystal region in the left half of the pixel, the liquid crystal molecules in the center of the cell cross section rise from the left, and in the liquid crystal region in the right half of the pixel, the liquid crystal molecules in the center in the cell cross section rise from the right. Become. In other words, the domain where the liquid crystal molecules at the center of the cell rise from the left (domain 1, FIG.
The pixel is divided into a middle 14) and a domain rising from the right (domain 2, 15 in FIG. 5). If the ray is tilted to the left,
The angle between the liquid crystal molecules in the domain 1 and the light beam increases, and the angle between the liquid crystal molecules in the domain 2 and the light beam decreases. On the other hand, when the light ray is tilted to the right, the magnitude relationship between the light ray and the angles formed by the domains 1 and 2 is reversed. Therefore, the optical characteristics of the entire pixel are symmetrical with respect to the left and right inclinations of the light beam, and the above-described image inversion and whitening due to the viewing angle are suppressed.

A liquid crystal display device having a structure similar to the above disclosed technology is disclosed in Japanese Patent Application Laid-Open No. Hei 6-43461 (FIG. 6, in which the twist of liquid crystal molecules is omitted for easy viewing). ). In the disclosed technology, the common electrode 5 is provided with an opening 7. When a voltage is applied to the liquid crystal display device, a liquid crystal alignment structure as shown in FIG. 6 is obtained due to the electric field disturbance 16 near the common electrode opening 7 in addition to the electric field disturbance 16 at the end of the pixel electrode 6. As a result, when a voltage is applied, a liquid crystal alignment structure similar to that in FIG. 5 is obtained, and the viewing angle dependency is suppressed.

On the other hand, in these liquid crystal display devices, the liquid crystal molecules at the boundary between domain 1 and domain 2 (hereinafter referred to as “domain boundary”) remain horizontal to the substrate when no voltage is applied even when voltage is applied. It is. Therefore, for example, in an element in a normally white mode (white display when no voltage is applied, black display when a voltage is applied), this boundary portion remains white even when a voltage is applied, and is black when a voltage is applied (when a voltage is applied). , The contrast ratio (= transmittance for white display / transmittance for black display) is reduced, and color saturation in color display is reduced. In order to remedy this drawback, a technique has been known in which a light-blocking layer is provided at the domain boundary to block transmitted light from the domain boundary.

[0009]

However, these conventional liquid crystal display devices have a problem that it takes a long time until the domain shape is stabilized when a voltage is applied to the pixel electrode.
This will be described below by taking a case where the common electrode has an opening as an example.

The liquid crystal inside the pixel is replaced with a liquid crystal X near the end of the pixel.
And a liquid crystal Y near the opening of the common electrode and a liquid crystal Z between the two liquid crystals (FIG. 7). Immediately after the voltage is applied, the liquid crystals X and Y
As described above, the state H shown in FIG.
Alternatively, the state L is uniquely taken. However, in the vicinity of the liquid crystal Z, the electric field is almost perpendicular to the substrate, so that a region taking the state H and a region taking the state L coexist, and a domain boundary is formed in the boundary region. As time elapses from the application of the voltage, the domains in the state H or the state L in X, Y, and Z merge, and the domain boundary moves accordingly. Eventually, the domain boundary disappears and becomes stable. FIG. 9 illustrates the time lapse of the above domains.

FIG. 9 shows, as an example, the lapse of time in a pixel having an opening 7 diagonally on the common electrode. When a voltage is applied, the liquid crystal around the electrodes responds to states H and L. However, in a region far from the periphery of the electrode, states H and L
Coexistence. Over time, domain fusion occurs, the L domain in the H domain and the H domain in the L domain disappear, and the pixel enters a steady state. However, the time T when the L domain in the H domain completes disappearing
L and the time TH at which the H domain in the L domain disappears do not always match. When viewed from the front, the H domain and the L domain show black display and cannot be distinguished.
However, when viewed obliquely, the H domain looks bright and the L domain looks dark, or vice versa. Therefore, when TL> TH and obliquely viewed, the disappearance process of the L domain is visible. This L
The disappearance process of the domain is recognized such that a bright state becomes dark or a dark state becomes bright. In addition, since light is transmitted through these domain boundaries, the contrast of pixels is reduced. Further, there is a problem that the domain boundary moves due to the fusion of the domains, and the light-blocking layer does not effectively contribute to blocking the transmitted light from the domain boundary. Further, since it takes a long time of one second or more immediately after voltage application until the fusion process between domains is completed, when displaying an image with fast movement, a phenomenon that a line is drawn after a moving image ( (Afterimage) is observed. A similar situation occurs in a pixel having the structure of FIG. 5 having no opening in the common electrode.

Further, in a device having an opening provided in the center of a rectangular pixel in parallel with one side of the rectangle, a domain boundary is formed in a diagonal direction of the rectangle immediately after voltage application due to the influence of a lateral electric field of the device. This has the problem that the domain boundary does not move to the position of the opening unless the time has elapsed on the order of seconds and the light cannot be effectively shielded (FIG. 1).
0).

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of a liquid crystal display device comprising a twisted nematic liquid crystal having a splay distortion when no voltage is applied. An object of the present invention is to provide a liquid crystal display device having a high speed, a high contrast ratio, and a wide viewing angle. For this purpose, the liquid crystal display device of the present invention achieves the above object by adopting a structure in which a small amount of polymer is dispersed in a liquid crystal layer. That is, the position of the domain boundary is fixed by the presence of a small amount of polymer dispersed in the liquid crystal, and the response speed and the contrast ratio do not decrease.

In addition, the present invention provides a method in which a small amount of a monomer or oligomer (hereinafter referred to as "monomer") is provided between a substrate having a common electrode and a substrate having a pixel electrode in which injected liquid crystal is combined so as to generate spray distortion when no voltage is applied. The present invention provides a method for manufacturing a liquid crystal display device, which achieves the above object by a method for manufacturing a liquid crystal display device in which a liquid crystal containing) is injected and then a monomer or the like is reacted. Further, in the present invention,
The above object is achieved by controlling the position of the domain boundary to the position of the light-shielding layer or the like by reacting such a monomer or the like under voltage application.

[0015]

The structure and operation of the present invention will be described with reference to FIG. FIG. 1 shows one embodiment in which the common electrode has an opening. The substrates 3 and 4 used in the liquid crystal display device of the present invention are subjected to an alignment treatment so that the liquid crystal molecules 2 have a splay distortion. Also, a small amount of polymer 1 is contained in the liquid crystal.
For example, distributed over a network.

When a voltage is applied, the liquid crystal molecules rise from two directions according to the same theory as that described with reference to FIG. 6, and a liquid crystal display device having little viewing angle dependence even in a halftone can be obtained. In a conventional liquid crystal display device in which no polymer is present in a liquid crystal layer, as described with reference to FIG. 9, two domain regions (domains H and L) having different rising directions change with time, and a domain boundary portion is changed. Move gradually. On the other hand, in the device of the present invention, the movement of the liquid crystal molecules 2 is restricted due to the polymer 1 existing in a small amount in the liquid crystal layer, and as a result, the domain boundary is fixed. As described with reference to FIG. 6, the rising direction of the liquid crystal molecules is unique in the X and Y portions, but is arbitrary in the Z portion. Actually, since the polymer existing in a small amount memorizes the rising direction when the voltage is first applied, the liquid crystal molecules also rise in the first rising direction thereafter, and the domain boundary does not move.

The present invention also provides a method for manufacturing such a liquid crystal display device. That is, in the present invention, the injected liquid crystal is subjected to an alignment treatment so as to generate a splay distortion when no voltage is applied, and a liquid crystal containing a small amount of monomer or the like is injected between the substrate having the combined common electrode and the substrate having the pixel electrode.
Thereafter, a method for manufacturing a liquid crystal display device in which a domain boundary does not move by reacting a monomer or the like is provided.

Another example provides a production method in which a monomer or the like is dissolved in a liquid crystal, and the monomer or the like is reacted after a liquid crystal solution is injected. In particular, by reacting a monomer or the like in a state where a low voltage that does not significantly change the initial transmittance is applied, an appropriate pretilt is generated in each domain portion, and the position of the domain boundary portion can be fixed.

In the present invention, a light-shielding layer can be arranged so as to match the opening 7 of the common electrode. Thus, it is possible to prevent light leakage from a domain boundary portion that does not enter a black display state when a voltage is applied. When a substrate provided with a light-shielding layer in such an opening is used, a low voltage that does not significantly change the initial transmittance is applied, and after a sufficient time elapses, the domain boundary moves and coincides with the opening. By curing the monomer as shown in the lower part of FIG. 10, the domain boundary can be fixed at a position corresponding to the light-shielding layer. In this case, light leakage from the domain boundary is blocked by the light shielding layer, and a liquid crystal display device with high contrast can be obtained. In particular, in a rectangular pixel, a domain boundary is likely to be generated in a diagonal direction immediately after voltage application, and providing a light-shielding layer at this position reduces the aperture ratio of the pixel. In contrast, in the case of the present invention, the application of a low voltage causes the domain boundary to move to the vertical opening at the center of the pixel, and then fixes the domain boundary, thereby increasing the aperture ratio and improving contrast. A high liquid crystal display device can be obtained.

Although FIG. 1 illustrates the case where the common electrode has no opening, it is apparent that these inventions can be applied to the case where the common electrode has no opening.

Hereinafter, the materials constituting the present invention will be described.

As the polymer dispersed in the liquid crystal layer in the present invention, a polymer obtained by dissolving and dispersing a polymer in a liquid crystal can be introduced between substrates, or a liquid crystal in which a monomer or the like is dissolved is introduced between substrates. Later, a monomer or the like may be reacted to form a polymer.

The polymer used in the present invention may have a structure similar to that of liquid crystal molecules. However, since it is not used for the purpose of aligning liquid crystals, the polymer has flexibility such as having an alkylene chain. May be provided.
In particular, in the method of dissolving and dispersing a polymer in a liquid crystal, the polymer chain has a certain degree of flexibility and is easily dissolved in the liquid crystal because it is not easy to dissolve and disperse the polymer in the liquid crystal. Things are desirable.

The liquid crystal display device of the present invention can be manufactured by a method of dissolving and dispersing a polymer in a liquid crystal. However, in view of easiness of injection of a liquid crystal solution and stabilization of initial alignment, etc. A method of reacting a monomer or the like is more preferable.

As the monomers and oligomers used in the present invention, any of photo-curable monomers, thermo-curable monomers, and oligomers thereof can be used, and if they contain these, they contain other components. You may go out. The "photocurable monomer or oligomer" used in the present invention includes not only those which react with visible light but also ultraviolet curable monomers which react with ultraviolet light, and the latter is particularly desirable from the viewpoint of easy operation. Also, monomers,
The oligomer may be a monofunctional one, a difunctional one, or a monomer having a trifunctional or higher polyfunctionality.

The light or ultraviolet curable monomer used in the present invention includes, for example, 2-ethylhexyl acrylate, butyl ethyl acrylate, butoxyethyl acrylate, 2-cyanoethyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, Ethoxyethyl acrylate, N, N-diethylaminoethyl acrylate,
N, N-dimethylaminoethyl acrylate, dicyclopentenyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, isobonyl acrylate, isodecyl acrylate, lauryl acrylate, morpholine acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 2,2,3,4
Monofunctional acrylate compounds such as 4,4-hexafluorobutyl acrylate, 2-ethylhexyl methacrylate, butylethyl methacrylate, butoxyethyl methacrylate, 2-cyanoethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 2
-Hydroxypropyl methacrylate, 2-ethoxyethyl acrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, glycidyl methacrylate,
Tetrahydrofurfuryl methacrylate, isobonyl methacrylate, isodecyl methacrylate, lauryl methacrylate, morpholine methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate Monofunctional methacrylate compounds such as 2,2,3,4,4,4-hexafluorobutyl methacrylate, 4,4'-biphenyl diacrylate, diethylstilbestrol diacrylate, 1,4-bisacryloyloxybenzene, 4,4'-bisacryloyloxydiphenyl ether, 4,4'-bisacryloyloxydiphenylmethane, 3.9-bis [1,1-
Dimethyl-2-acryloyloxyethyl] -2,4,
8,10-tetraspiro [5,5] undecane, α,
α'-bis [4-acryloyloxyphenyl] -1,
4-diisopropylbenzene, 1,4-bisacryloyloxytetrafluorobenzene, 4,4′-bisacryloyloxyoctafluorobiphenyl, diethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, Dicyclopentanyl diacrylate, glycerol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ditrimethylol Propane tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol mono Mud carboxy pentaacrylate, 4,
4'-diacryloyloxystilbene, 4,4'-diacryloyloxydimethylstilbene, 4,4'-diacryloyloxydiethylstilbene, 4,4'-diacryloyloxydipropylstilbene, 4,4'-
Diacryloyloxydibutylstilbene, 4,4'-
Diacryloyloxydipentylstilbene, 4,4 '
-Diacryloyloxydihexylstilbene, 4,
4'-diacryloyloxydifluorostilbene,
2,2,3,3,4,4-hexafluoropentanediol 1,5-diacrylate, 1,1,2,2,3
Polyfunctional acrylate compounds such as 3-hexafluoropropyl-1,3-diacrylate, urethane acrylate oligomer, diethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,3
-Butylene glycol dimethacrylate, dicyclopentanyl dimethacrylate glycerol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, pentaerythritol Trimethacrylate, ditrimethylolpropane tetramethacrylate,
Polyfunctional methacrylate compounds such as dipentaerythritol hexamethacrylate, dipentaerythritol monohydroxypentamethacrylate, 2,2,3,3,4,4-hexafluoropentanediol 1,5-dimethacrylate, and urethane methacrylate oligomer;
Examples include, but are not limited to, styrene, aminostyrene, vinyl acetate, and the like.

The driving voltage of the device of the present invention is also affected by the interfacial interaction between the polymer material and the liquid crystal material. Therefore, the driving voltage may be a polymer containing elemental fluorine. As such a polymer, 2,2,3,3,4,4-hexafluoropentanediol 1,5-diacrylate, 1,1,
2,2,3,3-hexafluoropropyl-1,3-diacrylate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2,2 3,3-tetrafluoropropyl acrylate, 2,2,3,4,4,4-hexafluorobutyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, Examples include, but are not limited to, polymers synthesized from compounds including 2,2,3,4,4,4-hexafluorobutyl methacrylate, urethane acrylate oligomers, and the like.

When a light or ultraviolet curable monomer is used as the polymer used in the present invention, an initiator for light or ultraviolet light is generally used. Various initiators can be used, for example, 2,2-diethoxyacetophenone, 2-hydroxy-2-methyl-1
-Phenyl-1-one, 1- (4-isopropylphenyl-)-2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-
Acetophenones such as 2-methylpropan-1-one,
Benzoin compounds such as benzoin methyl ether, benzoin ethyl ether and benzyl dimethyl ketal, benzophenone compounds such as benzophenone, benzoyl benzoic acid, 4-phenylbenzophenone and 3,3-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone , A thioxanthone such as 2-methylthioxanthone, a diazonium salt, a sulfonium salt,
Iodonium salts, selenium salts and the like can be used.

In the liquid crystal optical device of the present invention, a sufficient effect can be obtained even if the amount of the polymer material is considerably reduced.
More specifically, depending on the type of the polymer material and the interaction with the liquid crystal molecules, if the amount of the polymer material is 5% by weight or more of the entire liquid crystal layer, the alignment disorder and scattering are caused by the polymer and the contrast occurs. Is unfavorable because it causes a decrease in the density. If the content is 0.5% by weight or less, the domain boundary is not fixed even when a voltage is applied. Therefore, the amount of the polymer material is preferably 0.5% by weight or more and 5% by weight or less, and more preferably about 2% by weight, based on the total amount of the polymer material and the liquid crystal material.

Since the liquid crystal display device of the present invention has a small amount of a polymer, it can be easily mixed with a liquid crystal material, has a high degree of freedom in combination of a polymer and a liquid crystal, and has an advantage that element characteristics can be easily controlled. is there. Further, since the amount of the polymer is small, the increase in the viscosity of the solution when a monomer or the like is mixed with the liquid crystal material is small, and the solution can be introduced between the substrates by a liquid crystal injection technique similar to that of a normal TN liquid crystal panel. Can be easily produced.

The liquid crystal material used in the present invention is mainly a nematic liquid crystal containing a small amount of a chiral agent, but may not contain a chiral agent. The device of the present invention is a TFT
In order to drive the liquid crystal as an active element, it is required that the liquid crystal has a large electric resistance and a large charge retention rate. Therefore, it is a high-resistance liquid crystal material such as fluorine-based and chlorine-based,
It is also desirable that the charge retention characteristics do not decrease due to irradiation with visible light or ultraviolet light.

The light-shielding layer constituting the liquid crystal display device of the present invention can be disposed on the same substrate as the common electrode, or can be disposed on the same substrate as the TFT.
In the former case, if the light-shielding layer is formed of the same layer as the light-shielding layer for the TFT, the number of steps for forming the color filter substrate does not increase. In the latter case, if a layer used during the TFT forming process is used, the TFT substrate forming process is not complicated. For example, the light-shielding layer of the present invention can be formed while leaving a part of the gate layer or the drain layer of the TFT.

By using the present invention as described above,
The response speed is fast because the domain boundary is fixed,
It is possible to obtain a high-contrast wide-viewing-angle liquid crystal display device with no afterimage and no light leakage during black display.

[0034]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

(Embodiment 1) The size of one pixel is 50 μm ×
An amorphous silicon thin film transistor array having a size of 150 μm, a number of pixels of 480 × 640 × 3, and a diagonal size of a display screen of 120 mm was used. This amorphous silicon thin film transistor was formed on a glass substrate by repeating a film forming step and a lithography step.

On the other hand, a color filter substrate having a TFT light-shielding layer made of a chromium thin film, a color filter layer, an overcoat agent, and a common electrode layer made of an ITO thin film was used. The common electrode layer has a size of 40 μm × 5 μm.
Openings were provided.

After washing both substrates, a polyimide solution (AL1051 manufactured by Nippon Synthetic Rubber Co., Ltd.) was printed with an offset printing machine and baked at 90 ° C. and 200 ° C. Thereafter, a rubbing treatment was performed using a buff cloth made of rayon. The rubbing direction of each substrate is the direction shown in FIG.
Thereafter, an adhesive was applied to the periphery of the display screen on the TFT substrate 19, and latex balls having a diameter of 6 μm were sprayed on the color filter substrate 18 as spacers. Subsequently, the positions were adjusted so that the pixel structures on both substrates were aligned, and the substrates were bonded together under pressure. FIG. 11 shows the direction in which the two substrates are bonded to each other.

The bonded substrate is placed in a vacuum chamber, and after evacuation, a nematic liquid crystal (ZLI4792 manufactured by Merck) is used.
And a mixed solution of 4,4'-diacryloyloxybiphenyl acrylate (1 wt% based on liquid crystal) and benzoin methyl ether (1 wt% based on monomer). The left chiral agent is mixed in the nematic liquid crystal so that the natural pitch length is 70 μm. After sealing the injection hole, ultraviolet rays were irradiated. It remained transparent after irradiation.
A driving IC was connected to the produced cell to perform a display operation.

The state of domain generation in the manufactured liquid crystal display device was observed under an optical microscope. Domain boundaries were fixed and no migration was observed. In addition, a transmittance measuring device (viewing angle 30 ° measured using Otsuka Electronics LCD-5000)
Was 30 ms (5 V) when turned on and 40 ms when turned off.

After the manufactured liquid crystal display device was set on a rotating stage, a color luminance meter (BM-5 manufactured by Topcon Corporation) was placed in front of the device.
A) was installed, and the viewing angle dependence of the liquid crystal display device was examined. Eight gradations were displayed on the liquid crystal display screen, and the viewing angle dependence at each gradation display was measured. There was no reversal of the order of brightness between gray levels within a viewing angle range of 40 ° (the brightness order between gray levels was inverted within a viewing angle of 10 ° in a conventional twisted nematic liquid crystal).

Example 2 Nematic liquid crystal (ZLI47)
92) to polymethyl methacrylate (Tokyo Kasei Co., Ltd.)
Was added at 2% by weight and heated at 100 ° C. for 30 minutes under nitrogen substitution, whereby the polymethyl methacrylate was completely dissolved. A liquid crystal display device was manufactured in the same manner as in Example 1 except that this polymer-liquid crystal solution was used instead of the liquid crystal of Example 1 (however, no ultraviolet light was irradiated). The domain boundary of the liquid crystal display after voltage application hardly moved. Response speed at a viewing angle of 30 ° is 30 m when on
s (5V), 40 ms off.

Comparative Example 1 A liquid crystal display was produced in the same manner as in Example 1, except that no monomer was added to the liquid crystal.
The state of domain generation in the liquid crystal display device was observed under an optical microscope. The domain boundaries moved over time for over a second. The response speed measured using the LCD-5000 was 100 ms when turned on and 120 ms when turned off.

(Example 3) A cell was produced in the same manner using the same substrate as in Example 1 except that a light-shielding layer was provided in the opening. The same liquid crystal solution as in Example 1 was injected and sealed. Under the optical microscope, a voltage of 2.0 V higher than the threshold voltage by 0.1 V was applied to the obtained liquid crystal display device. Immediately after the application of the voltage, the domain boundary generated on the diagonal gradually moved to the opening. In this state, ultraviolet rays were irradiated.
Thereafter, even when the voltage was turned ON and OFF, the domain boundary did not move, and the domain boundary did not protrude from the light shielding portion. The contrast of the liquid crystal display was 150: 1.

An embodiment of the fifth invention will be described. In this embodiment, a color filter substrate 20 having the structure shown in FIG. 17 was used. The color filter substrate includes a light-shielding layer 11 made of a chrome thin film for a TFT, a color filter layer 21 containing a pigment, a light-shielding layer 24 containing a black pigment for a domain boundary portion, an overcoat layer 22 for planarizing the surface, and A common electrode 8 made of an ITO thin film having an opening 10 is provided. Opening width of common electrode is 5μm
And the width of the light shielding layer is 8 μm. Except for the color filter structure, a liquid crystal display device was manufactured in the same process as the embodiment of the first invention. Thereafter, display driving was performed between the orthogonal polarizing plates under a polarizing microscope, and the pixels were observed. It was confirmed that the bright line observed in the embodiment of the fourth invention was hidden by the light shielding layer 24.

Example 4 A liquid crystal display was produced in the same manner as in Example 2 except that hexanediol diacrylate was used as a monomer. Microscopic observation revealed that the domain boundary was fixed, and was 50 ms (5 V) when turned on and 55 ms when turned off.

[0046]

As described above, according to the present invention, a liquid crystal display device having a high response speed, an excellent contrast ratio and a wide viewing angle can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a liquid crystal display device of the present invention.

FIG. 2 is a cross-sectional view illustrating a conventional TN liquid crystal display device.

FIG. 3 is a cross-sectional view for explaining the viewing angle dependence of a conventional TN liquid crystal display device.

FIG. 4 is a cross-sectional view illustrating a conventional liquid crystal display device.

FIG. 5 is a cross-sectional view illustrating a conventional liquid crystal display device.

FIG. 6 is a cross-sectional view illustrating a conventional liquid crystal display device.

FIG. 7 is a cross-sectional view for explaining a problem of a conventional liquid crystal display device.

FIG. 8 is a cross-sectional view for explaining a problem of a conventional liquid crystal display device.

FIG. 9 is a plan view showing movement of a domain boundary line of a conventional liquid crystal display device.

FIG. 10 is a plan view showing movement of a domain boundary line of a conventional liquid crystal display device.

FIG. 11 is a perspective view showing a rubbing direction of the liquid crystal display device.

[Explanation of symbols]

 Reference Signs List 1 polymer 2, 14, 15 liquid crystal molecule 3 upper substrate 4 lower substrate 5 common electrode 6 pixel electrode 7 opening 11 pretilt angle 12, 13 light beam 16, 17 electric field disturbance 18 color filter substrate 19 TFT substrate 20 rubbing direction

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-40281 (JP, A) JP-A-4-149410 (JP, A) JP-A-6-43461 (JP, A) JP-A-6-43461 250160 (JP, A) JP-A-2-29488 (JP, A) JP-A-4-212931 (JP, A) JP-A-5-88151 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) G02F 1/137 G02F 1/13 101 G02F 1/1333 G02F 1/1337

Claims (8)

(57) [Claims] 1. A liquid crystal display device having a structure in which a liquid crystal having a splay distortion when no voltage is applied is sandwiched between two electrode substrates, wherein a liquid crystal layer has a small amount of a polymer. apparatus. 2. The liquid crystal display device according to claim 1, wherein the polymer is a polymer formed by reacting a photocurable monomer or oligomer. 3. The method according to claim 1, wherein the polymer is 0.5% by weight or more of the whole liquid crystal layer.
% By weight or less.
The liquid crystal display device as described in the above. 4. A substrate having a common electrode and a pixel electrode
A tool that has splay distortion when no voltage is applied to the substrate
Liquid crystal with structure sandwiching isted nematic liquid crystal
The display device has a small amount of polymer in the liquid crystal layer.
Wherein the common electrode has an opening. 5. The liquid crystal display device according to claim 4, further comprising a light shielding layer aligned with the opening of the common electrode. 6. A liquid crystal containing a small amount of a monomer or an oligomer is injected between a substrate having a common electrode and a substrate having a pixel electrode combined so that the injected liquid crystal causes a splay distortion when no voltage is applied. Alternatively, a method for manufacturing a liquid crystal display device, comprising reacting an oligomer to form a polymer. 7. The method according to claim 6, wherein after the voltage is applied, the boundary of the domain is moved to the opening of the common electrode or the light-shielding portion, and then the monomer or oligomer is reacted to fix the boundary of the domain. Of manufacturing a liquid crystal display device. 8. The method according to claim 6, wherein the monomers or oligomers are reacted by irradiating them with ultraviolet rays.
The manufacturing method of the liquid crystal display device according to the above.