JPH10311972A - Liquid crystal display device, liquid crystal projector using the same and production of the liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent display luminance unevenness and to ameliorate color irregularity when three colors are synthesized as a liquid crystal display device by varying the network structure of polymers in first and second polymer-contg. liquid crystal regions. SOLUTION: The examples of the polymer materials of the liquid crystals 7 in a first region which is a polymer network liquid crystal layer include polyacrylate, polymethacrylate, etc. The examples of the liquid crystalline material include nematic liquid crystals, cholesteric liquid crystals, etc. On the other hand, spacers 4 for controlling the thickness of the polymer network liquid crystal layer are evenly mixed with sealants 3 which are the liquid crystals of the second region and a uniform pressure is applied thereon in such a manner that display characteristics are made uniform within the panel, by which the device is formed. As a result, the second region turns to be a stress relieving layer with respect to the first region enclosed by light shielding members and irradiated in first and second two stages, by which the network of the display section is made uniform.

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 formed by mixing a polymer with liquid crystal, a liquid crystal projector using the same, and a method of manufacturing the liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices, such as a direct-view display having a diagonal size exceeding 10 inches, have been used in a wide range of devices because of their advantages such as thinness, low voltage driving, and power saving. In addition, with the spread of computers, liquid crystal projectors that can arrange a liquid crystal panel together with an optical system and perform enlarged projection to obtain a large-screen display are also available as practical products with high resolution and high brightness. It is starting to appear.

The liquid crystal used in these liquid crystal panels is generally a TN (Twisted Nematic) type liquid crystal, and has a faster response and higher contrast than STN (Super Twisted Nematic) type liquid crystal, which has conventionally been mainstream. Since it is high, a higher-quality image can be displayed.

However, in a display device using a TN liquid crystal, there is a limit in brightness due to a large light loss caused by a polarizing plate. In particular, in a projection type liquid crystal display device requiring high luminance, the drawback of the TN type liquid crystal display device was remarkable.

[0005] One solution to this problem is to incorporate T in a liquid crystal continuous phase or a sponge-like polymer network.
Polymer Network Liquid Crystal (PN
LC: Polymer Network Liquid Crystal), or “Polymer / Liquid Crystal Composite Film” that can form a bright large-area display that does not use a polarizing plate by using the electro-optic effect with light scattering, and a polymer between transparent electrodes When the liquid crystal molecules have a structure in which spherical liquid crystal particles are dispersed in the matrix and the liquid crystal molecules are aligned along the polymer matrix wall inside the particles and there is a difference between the average refractive index of the liquid crystal particles and the refractive index of the polymer matrix. When the incident light is scattered and a voltage is applied to the polymer dispersion cell, the difference in the refractive index of the liquid crystal increases, and the liquid crystal moves away from the constraint of the wall of the polymer matrix, becomes perpendicular to the transparent electrode surface, and is refracted by the polymer matrix. Liquids that are expressed in various ways, such as "polymer-dispersed liquid crystals" that can transmit incident light without scattering when the refractive index and the refractive index of the liquid crystal molecules in the minor axis direction are close to each other Display device has been proposed.

One of the reasons is that when a voltage is applied, the refractive index of the TN liquid crystal substantially matches the refractive index of the polymer network, so that light is transmitted with a high transmittance, and when no voltage is applied, the TN liquid crystal and the polymer network are arranged randomly. There is PNLC as a device that performs black display by scattering incident light due to the refractive index difference of the PNLC. Since a display device using PNLC (polymer network liquid crystal) does not use a polarizing plate, a light display efficiency is higher than that of a TN liquid crystal display device, that is, a bright display is obtained. These phenomena and utilization are the same for the “polymer / liquid crystal composite film” and the “polymer dispersed liquid crystal”.

It is effective to make the active matrix substrate a reflection type in order to make the high light use efficiency such as “polymer network liquid crystal” more effective. The reflection type substrate can embed an active element under the reflection electrode and also function as a light shield. Therefore, the aperture ratio can be increased to nearly 100%. It has the potential that the usage efficiency does not decrease.

Here, when a liquid crystal display device is manufactured using a reflective polymer network liquid crystal, a polymer / liquid crystal composite film, or a polymer dispersed liquid crystal, an active element is reflected on a reflective substrate. It is known that a liquid crystal panel is formed by embedding under an electrode, injecting a polymer and a liquid crystal between the substrate and the transparent electrode and sealing the resultant, and then irradiating ultraviolet rays (UV).

[0009] In particular, a method for producing the above-mentioned "polymer-dispersed liquid crystal" is described in JP-A-5-61016. According to this publication, an acrylate-based ultraviolet-polymerizable composition (Darocur 1116, a photopolymerization initiator used by Merck) and a liquid crystal composition (E8, manufactured by BDH) are uniformly dissolved to have an ITO electrode. After being injected into the glass cell, ultraviolet rays are irradiated (1 mW, 500 seconds), and the polymer dispersed liquid crystal (P
DLC (Polymer Dispersed Liquid Crystal) cells are manufactured. The particle diameter of the liquid crystal composition in the PDLC material is 0.1 to 10 μm, and the particle diameter of the liquid crystal composition is adjusted by the content of the liquid crystal composition. That is, with respect to the total weight of the polymer matrix and the liquid crystal composition, 6
Samples having different particle sizes are prepared using a liquid crystal composition of 5 to 75% by weight.

[0010]

However, it has been found that display unevenness occurs in the case of a conventional liquid crystal panel irradiated with ultraviolet rays. In particular, when parallel ultraviolet rays are applied to the entire surface of the liquid crystal region, a phenomenon in which the amount of reflected light falls concentrically on the central portion and the peripheral portion of the liquid crystal panel, that is, a phenomenon in which the transmittance decreases. In the case of the color three-plate type, color unevenness occurs concentrically. The reason for this is due to the non-uniformity of the polymer polymerization state or the non-uniformity of the liquid crystal particle diameter, which can be predicted to be due to the stress during the polymer polymerization reaction. It is also predicted that another cause is that the influence of the seal during polymer polymerization varies depending on the distance from the seal.

It has also been found that there is a problem with the stability of the liquid crystal. That is, it was found that the stability of the liquid crystal phase was lacking due to the presence of the unreacted liquid crystal phase at the time of preparation with ultraviolet rays.

A sectional view of a liquid crystal display device into which liquid crystal is injected will be described with reference to FIG. The present applicant has disclosed a method of manufacturing an active matrix substrate as disclosed in Japanese Patent Application No. 7-1864.
No. 73 has been filed. The active matrix substrate is configured as follows. An n-type silicon semiconductor substrate 201 having an impurity concentration of 10 ¹⁵ cm ⁻³ or less;
And 202, the impurity concentration of 10 ¹⁶ cm ^-3 of about a p-type impurity regions PWL203, NLD206 is n-type impurity region of about impurity concentration 10 ¹⁶ cm ^-3, impurity concentration 1
Source and drain regions 207 and 20 of about 0 ¹⁹ cm ^-3
7 ', Al electrode 209, PSG 211, SiN2
The lower part of the liquid crystal 214 is constituted by 10 and the pixel electrode 213.

Next, a transparent substrate 220, a color filter 221, a black matrix 222, and a common electrode 223 made of ITO or the like are provided above the liquid crystal 214. However, for the purpose of the present invention, the color filter 221 and the black matrix 222 that do not transmit ultraviolet light are not used, and the layers thereof are unnecessary. The active matrix substrate used in the present invention has one color per color.
This is because sheets are used and the color filter does not transmit ultraviolet light. Therefore, for the purposes of the present invention, the liquid crystal 2
A transparent substrate 220 such as glass having a transparent electrode deposited on the liquid crystal 214 side or a common substrate 22 such as ITO
3 and a transparent substrate 220. However, when applying the R, G, B matrix liquid crystal display device, it is necessary that each color filter and the black matrix transmit ultraviolet rays to some extent. Note that, in the active matrix substrate having the above structure, the surface of the pixel electrode 213 is smooth, and an insulating layer is buried in a gap between adjacent pixel electrodes. I have.

Here, a plan view of the liquid crystal display device will be described with reference to FIG. The figure shows the relationship between the seal structure and the panel structure. 7, 51 is a seal part,
52 is an electrode pad, 53 is a clock buffer circuit, 5
4 is an amplifier. This amplifier 54 is used as an output amplifier at the time of panel electrical inspection. 55 is an Ag paste part for taking the potential of the counter substrate, 56 is a display part, 57
Reference numeral denotes a peripheral circuit unit such as a horizontal / vertical shift register (HSR, VSR). As shown in FIG. 6, both inside and outside the seal, so that the total chip size is small,
A circuit is provided. In this embodiment, the pad drawers are concentrated on one side of the panel. However, both sides on the long side can be taken out from multiple sides instead of one side. It is valid.

[0015]

SUMMARY OF THE INVENTION The present invention has been achieved through the results of extensive trial production and repeated experiments in order to solve the above-mentioned problems of uneven display luminance and stability of liquid crystal.

The liquid crystal display device of the present invention comprises: a first polymer-containing liquid crystal region constituting a first region including a display region;
A second polymer-containing liquid crystal region constituting a second region outside the first region; and wherein the first and second polymer-containing liquid crystal regions have different polymer network structures. And

Further, in the method of manufacturing a liquid crystal display device according to the present invention, a liquid crystal material and a prepolymer material are disposed between a pair of transparent substrates, and a polymerization reaction is caused in the prepolymer material. In a method of manufacturing a liquid crystal display device configured by irradiating light to polymerize the prepolymer material, a first region including a display region is irradiated with first light, and then a first region outside the first region is irradiated. The second region and the first region are irradiated with second light.

In the liquid crystal display device of the present invention, the second region is a stress relaxation region, and the polymer network in the first region including the display region is made uniform. Thereby, display unevenness and luminance unevenness are prevented.

Further, according to the present invention, since the second region functions as a layer for alleviating the alignment regulating force from the seal portion, the display region is less likely to be affected by the seal portion, and the display brightness unevenness and color unevenness are reduced. Is greatly improved.

Further, by performing the first and second two-step irradiation, all the liquid crystal mixture is reacted, the instability of the liquid crystal is eliminated, and the reliability of the liquid crystal display device can be improved.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal panel in which a polymer and a liquid crystal are sealed is provided with a seal frame including at least a display area and is irradiated with intense ultraviolet rays (hereinafter referred to as “ultraviolet rays” or “UV”) for a short time. The present invention has been made based on the finding that display unevenness is reduced by irradiating the entire liquid crystal region of the liquid crystal panel with weak ultraviolet rays for a long time thereafter.

According to the present invention, by irradiating only the display area (or the area including the display area) with ultraviolet light during ultraviolet irradiation, the stress caused by the polymer polymerization reaction occurring at the time of ultraviolet irradiation is released outside the ultraviolet irradiation area. . Therefore, the polymerization reaction (polymer formation or network formation) becomes uniform in the irradiation area, and is not directly affected by the surface of the sealant, so that the unevenness of display characteristics is improved. It was also found that the hysteresis and response speed of the display area were improved by the two irradiation steps.

In addition, after the above-mentioned relatively strong first-stage ultraviolet irradiation that causes the polymer polymerization reaction, the entire surface is relatively weakly subjected to the second-stage ultraviolet irradiation.
In the first stage, it causes a weak polymerization reaction in the non-irradiated area,
The reliability is secured, and the hysteresis and the response speed of the display area are improved as compared with the case where the first-stage irradiation is not performed.

Depending on the irradiation of the ultraviolet rays, a fine polymer network structure is formed in the ultraviolet irradiation region in the first stage, and a large polymer network structure is formed in regions other than the ultraviolet irradiation region.

FIG. 8 is a sectional view of a liquid crystal layer used in the liquid crystal display device of the present invention. In the figure, A indicates a polymer material portion, and B indicates a liquid crystal material portion. The prepolymer material forms a network structure shown in FIG. 8 by photopolymerization. In the ultraviolet irradiation region of the first stage, the average diameter of the mesh holes formed by the polymer becomes small, and outside the ultraviolet irradiation region, the average diameter of the mesh holes becomes relatively large.

The present invention includes an embodiment in which the first stage and the second stage of the irradiation with the illuminance are changed. According to this, the process of forming the network and the process of removing the residual monomer during the formation of the polymer network liquid crystal can be controlled independently, so that the characteristics of the polymer network liquid crystal can be optimized comprehensively.

According to the present invention, it is possible to obtain a liquid crystal characteristic having a high response speed and a small hysteresis without sacrificing the contrast ratio. Therefore, an overall improvement in image quality as a display device can be realized.

Embodiment 1 (1: Configuration of Liquid Crystal Display) A liquid crystal panel according to a first embodiment of the present invention will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes an active matrix substrate manufactured using a semiconductor process and having a reflective electrode on the surface. The reflective electrode of the active matrix substrate preferably has a high flatness and a high reflectance with respect to visible light. For example, in the present embodiment, aluminum or another element (for example, silicon, copper, titanium, or the like) is used as a material for an electrode in a trace amount (0.
(About 5-3.0%). Since the substrate surface in contact with the liquid crystal layer is almost completely flat,
The effect of eliminating unevenness in display characteristics due to a difference in liquid crystal thickness and unevenness in injecting liquid crystal due to a step difference was observed. Each pixel electrode in the active matrix substrate 1 is connected to a drain of a switching element. As the switching element, a MIM switch, a Diode switch, a three-terminal thin film transistor, a single crystal silicon transistor using bulk silicon, or the like, which is a two-terminal device, is preferable. Further, as a thin film transistor, an amorphous silicon transistor, a polysilicon transistor, an SOI (Silicon On Insulator) single crystal transistor and the like are known. Any of the switching elements described above is possible in this embodiment. In the present embodiment, the switching element is configured using single crystal silicon transistors using bulk silicon.

Further, a light-shielding layer (for example, titanium) for shielding incident light is provided between the switching element and the reflective electrode to prevent the element from malfunctioning due to light.

Further, the active matrix substrate has a built-in drive circuit including an on-chip horizontal and vertical shift register, and realizes high-speed signal processing corresponding to many pixels and high definition at low cost. .

In this embodiment, the reflection type active matrix substrate is used. However, the present invention can be applied to a transmission type active matrix substrate, and the same excellent effects can be obtained.

Next, reference numeral 2 denotes an opposite glass. It is desired that the glass has a thickness of about 0.5 mm to 3.0 mm, a high flatness, and a thermal expansion close to that of the active matrix substrate.
For example, in this embodiment, a non-alkali glass (NH-35, manufactured by NH Techno Glass) having a thickness of 1.0 mm was used. In a reflection type liquid crystal panel, the surface reflection of the facing glass and the interface reflection at the liquid crystal / glass interface cause a decrease in contrast. As a countermeasure, in the present embodiment, an anti-reflection coating is applied to the surface side, and the film configuration on the interface side with the liquid crystal is considered. That is, ITO (In) in contact with the liquid crystal surface
(dium-Tin-Oxide) ITO, a transparent film having a lower refractive index than glass (for example, MgF ₂ : n = 1.3) between the transparent electrode and the glass
8), the film thickness is selected so that the reflection is minimal at the wavelength of the incident light.

The present liquid crystal panel can be used as a component of a single-plate color display device by providing an on-chip color filter on the active matrix substrate 1. When the present liquid crystal panel is used as a three-panel projection display, it is desirable to prevent reflection in accordance with the light wavelengths of R, G, and B colors.

Reference numeral 3 denotes a main sealant for keeping a parallel distance between the opposing glass 2 and the active matrix substrate 1 and for sealing the polymer network liquid crystal. As the main sealant 3, thermosetting resin, UV curing resin, UV
A thermosetting resin is used. Main sealant 3
Is manufactured by uniformly mixing a spacer agent 4 for controlling the thickness of the polymer network liquid crystal layer and applying uniform pressure so that the display characteristics become uniform in the panel. Examples of the material of the spacer 4 include silica and resin. Further, the shape of the spacer 4 includes a cylindrical shape and a spherical shape, and any of them can be used. In order to accurately form the gap, a columnar spacer made of silica was used while paying attention to damage to the base. The seal area is formed on the outer periphery of the display area 5 with a reasonable space margin, and is formed such that the second area having large liquid crystal grains works effectively.

Reference numeral 6 denotes a liquid crystal injection port. The inlet is sealed with an end seal. As the end seal, for example, allyl resin, modified epoxy resin, epoxy acrylate, or the like can be used.

Reference numeral 7 denotes a polymer network liquid crystal layer. Examples of the polymer material include polyacrylate and polymethacrylate. The liquid crystal material includes a nematic liquid crystal and a cholesteric liquid crystal, and examples thereof include a biphenyl-based, phenylbenzoate-based, and phenylcyclohexane-based liquid crystal composition. Also, the structure may be controlled by photopolymerization using a three-component premixture of liquid crystal / monomer / oligomer, and the liquid crystal has a large dielectric anisotropy and a large refractive index anisotropy.
In E-8 ", the monomer may be 2-ethylhexyl acrylate, and the oligomer may be a urethane acrylate oligomer.

(2: Projection type liquid crystal display device and evaluation device)
A system for evaluating a projector using the polymer network liquid crystal display device described above will be conceptually described.

By arranging three panels for liquid crystal panels R, G and B in an optical system to constitute a projector,
A high-brightness, high-resolution, high-quality projection display can be realized.

In this embodiment, the manufactured liquid crystal panel is arranged in the optical system of the projector of the projection type liquid crystal display device shown in FIG.
In FIG. 7, a light source 71 that emits parallel light from a point light source such as a metal halide lamp or a xenon lamp, a condenser lens 72 that collects the parallel light, and a Fresnel lens 73 that converts the collected lens into parallel light And Fresnel lens 7
A reflecting mirror 74 that reflects the parallel light from the third mirror 3, a Fresnel lens 75 that collects the reflected light of the reflecting mirror 74, a reflecting mirror 76 that reflects the collected light to the liquid crystal panel side, and a reflection from the reflecting mirror 76. A field lens 77 for converting light into parallel light, a liquid crystal panel 78 to be evaluated, a projection lens and a color separation mirror for condensing and enlarging reflected light of the liquid crystal panel 78 through the stop 78 via the field lens 77 are provided. And a screen 81 for projecting an image driven by the liquid crystal panel 78.

Here, the F value of the parallel light projection optical system for the liquid crystal panel is 8.0. Light emitted from the light source 71 is modulated and reflected by the liquid crystal panel 78, expanded by the projection lens 80, and projected on the screen 81. 250 for the light source 71
Although evaluation was performed using the metal halide lamp (W), a high-pressure mercury lamp, a xenon lamp, or the like can be used as a projection display device. The output power is not limited to the above. The evaluation was performed on the G channel unless otherwise specified, and the center wavelength was 550 (nm).

When a projection type display device is formed by using R, G, and B plates, light from a light source is color-separated by a dichroic mirror or the like, and liquid crystal panels corresponding to each color are spatially arranged. It is sufficient that they overlap on 81. In this case, even if three liquid crystal panels are used for R, G, and B, a light source system such as a light source and a condensing lens and an optical system including a projection lens and a screen are commonly used.
It is possible to form a small full-screen projection type liquid crystal display device or a thin rear projection type liquid crystal display device including a large reflecting mirror on a screen.

(3: Method of Manufacturing Liquid Crystal Panel) A method of manufacturing the present liquid crystal panel will be described below.

An active matrix substrate 1 cut for each panel and an opposing glass 2 corresponding to the active matrix substrate 1 were prepared, and both were cleaned in a clean environment so as to prevent foreign matter and dust from entering. For cleaning, deionized ultrapure water with a surfactant added and bubbled with carbon dioxide, or ultrapure water while applying ultrasonic waves was effective. Since the surface of the reflective electrode is easily affected by a chemical solution, an extremely thin protective film may be formed on the surface in some cases. In the case of aluminum, it is also effective to form a natural oxide film on the surface by any method.

After sufficiently rinsing with ultrapure water, the paper was dried more thoroughly after drying the IPA paper.

Next, the main sealing agent mixed with a spacer agent was applied on the active matrix substrate 1 in a desired shape. As the main sealant, World Lock 706 manufactured by Kyoritsu Chemical Sangyo Co., Ltd., which is used in combination with UV heat curing, was used. Although the thickness of the polymer network liquid crystal layer can be 5 μm to 20 μm, in the present embodiment, it is 13 μm. For that purpose, a 13 μm spacer agent was used.

Further, a silver paste was applied to a predetermined position to establish conduction between the active matrix substrate 1 and the ITO transparent electrode on the surface of the counter glass 2.

Next, the active matrix substrate 1 and the counter glass 2 were bonded by a bonding apparatus. At the time of bonding, a pressure was applied substantially in parallel with the substrate, and the spacer was uniformly pressed so that the diameter of the spacer agent became almost equal to the liquid crystal thickness on the front surface of the panel.

In the case of the main sealant used in this embodiment, the main sealant is cured by irradiating UV light here.
Further, a heat treatment at 120 ° C. is applied for 60 minutes as after-curing to complete the curing of the main sealant. When a UV curing type is used, UV light is irradiated at this stage to cure the main sealant. In particular, in the case of a thermosetting type, the gap thickness tends to change due to contraction and expansion during thermosetting.
As a countermeasure, it was effective to perform heat treatment while appropriately pressing the panel. In order to effectively remove gas and volatile components contained in the main sealant, it is also effective to evacuate and degas after curing.

(4: Liquid Crystal Injection Step) The cells after the bonding are subjected to liquid crystal injection in the liquid crystal injection step. For liquid crystal injection, a cell and a syringe containing the liquid crystal / prepolymer mixture composition are placed in a liquid crystal injection device, and the liquid crystal /
This is performed by dropping the liquid crystal / prepolymer mixed composition from the syringe into an injection port for injecting the prepolymer mixed composition. The liquid crystal / prepolymer mixed composition referred to in the present embodiment refers to a solution in which a liquid crystal component and a prepolymer component are mixed. Preferably, the solution is homogeneous.

Hereinafter, the liquid crystal injection step will be described in detail. The liquid crystal injection device is composed of a high vacuum exhaust inside a degassing chamber cell for degassing the liquid crystal / prepolymer mixture composition, and a cell chamber for liquid crystal injection. First, the liquid crystal / prepolymer mixture composition is heated in an oven preheated to about 50 ° C. for 30 minutes, and then stirred for 1 minute to form a homogeneous phase, and then a syringe for injecting the liquid crystal / prepolymer mixture composition into the degassing chamber. Fill. The syringe filled with the liquid crystal / prepolymer mixture composition is set in a degassing chamber, and then the cell is set in a cell holding cassette and set in a predetermined position in the cell chamber. The liquid crystal injection device deaerates the liquid crystal / prepolymer mixture composition, evacuates the cell to a high vacuum, heats the cell,
It is set so that pressure control in the cell chamber and the degassing chamber, valve opening / closing, injection of the liquid crystal / prepolymer mixed composition from the syringe into the cell, and opening of the cell after injection to the atmosphere are all performed in an automatic sequence.

In the liquid crystal injecting step, a degassing chamber is used to prevent fluctuations in the composition of the liquid crystal / prepolymer mixture composition due to a difference in the amount of evaporation between components having different vapor pressures among the components of the liquid crystal / prepolymer mixture composition. Is 0.01 Torr to 1
It is desirable to be between 0 Torr, and in this embodiment, it is set to 0.5 Torr. The deaeration time is desirably 1 minute to 100 minutes, and is set to 10 minutes in the present embodiment. In addition, when evacuation is performed in the cell chamber, it is effective to heat the cell in order to remove impurities in the cell and trace components generated from the main sealant. Heating at room temperature or higher and at a temperature lower than the decomposition temperature of the main sealant is effective. The degree of vacuum is 10
The higher the vacuum and the longer the time, the higher the effect can be expected at Torr or less. After the evacuation of the cell, the pressure in the cell chamber is reduced by introducing a slight amount of nitrogen to reduce the degree of vacuum in the cell chamber and minimize the change in the composition of the liquid crystal / prepolymer mixture composition when injecting liquid crystal from a syringe. I made it. In this embodiment, the degree of vacuum at the time of liquid crystal injection is 0.5 Torr.
r. Further, before the liquid crystal / prepolymer mixed composition is dropped from the syringe into the injection port provided in the cell, a dummy dispensing is always performed, and the liquid crystal / prepolymer mixed composition having a changed composition attached to the tip of the syringe is placed inside the cell. It was not introduced.

The injection of the liquid crystal / prepolymer mixture composition was completed in about 15 minutes after the liquid crystal / prepolymer mixture composition was dropped into the injection port of the cell.

In this embodiment, the liquid crystal injection method is
An example of using the method of dropping the prepolymer mixture composition into the sealing port of the cell was described. Other methods of contacting the sealing port of the cell with the container containing the liquid crystal / prepolymer mixture composition in the cell chamber under normal pressure A method of dropping the liquid crystal / prepolymer mixture composition into the injection port, and a method of contacting the sealing port of the cell with a container containing the liquid crystal / prepolymer mixture composition under normal pressure were also tried, but in all cases, injection was performed normally. It was confirmed.

The temperature of the liquid crystal / prepolymer mixture composition and the temperature of the cell do not become lower than the phase separation temperature of the liquid crystal / prepolymer mixture composition until the UV irradiation is performed in the liquid crystal injection step and the subsequent UV irradiation step. You have to be careful. If the temperature is lower than the phase separation temperature, a polymer network structure formed later cannot be formed normally, which causes deterioration of display characteristics.

Further, after injecting the liquid crystal, U
Until V irradiation is performed, factors that promote the polymerization reaction, such as irradiation of the liquid crystal / prepolymer mixture with UV light, temperature rise, and elapsed time, must be eliminated as much as possible.

After cleaning the liquid crystal / prepolymer mixed composition and foreign matters adhered to the cell surface, the UV
Irradiation is performed. The UV irradiation on the cell surface is applied to the liquid crystal / prepolymer mixture composition injected into the cell and the UV in the photosensitive wavelength region is applied.
The irradiation is performed to polymerize the prepolymer component by irradiating light, and at the same time, to promote the phase separation between the liquid crystalline component and the prepolymer component, thereby forming a polymer network structure made of a UV curable resin inside the cell.

(5: Light Irradiation Step) The UV irradiation on the liquid crystal panel will be described with reference to FIG. In FIG. 2, a parabolic mirror 12 is arranged so as to emit ultraviolet light from an arc tube 11 and emit parallel light at the back thereof. The light passes through a short wavelength cut filter 13 to irradiate a liquid crystal panel.

First, in the first irradiation, the light-shielding member 20 is provided on the glass 2, and the light-shielding frame is set so as to be hidden inside the seal member 3, and is irradiated with high intensity light for a short time. next,
The light shielding member 20 is removed by the second irradiation, and irradiation is performed for a long time at low light intensity. The intensity can be controlled by controlling the level of the power supply voltage to the arc tube 11, or a neutral density filter may be provided between the arc tube 11 and the liquid crystal panel.

In the UV irradiation apparatus used in this embodiment, a 4 kW ultra-high pressure mercury lamp was used as a light source. This UV irradiation device is provided with an optical filter for cutting short-wavelength UV of 350 nm or less in order to prevent decomposition of the liquid crystal / prepolymer mixture composition and the constituents of the polymer network structure formed after UV irradiation.

The cell temperature at the time of UV irradiation was 19.0 ° C. The cell temperature was controlled by placing the cell on a thermal chuck: TC2800 manufactured by TRIO-TECH, and the cell temperature was monitored by bringing a thermocouple into direct contact with the thermal chuck. The temporal stability of the thermal chuck temperature was within ± 0.2 ° C.

In order to selectively irradiate a desired position on the cell surface with UV light, a UV light shielding frame was prepared. As the material of the light-shielding frame, a 0.3 mm-thick steel plate whose surface was subjected to black zinc plating was used, and an opening was provided in the UV irradiation region. After tightly fixing the light-shielding frame on the cell surface, the cell was placed on a thermal chuck in a UV irradiation device, and UV irradiation was performed.

When UV irradiation was performed on the cell surface, the liquid crystal material was phase-separated and polymerized within a few seconds, and the inside of the cell, which was transparent before the UV irradiation, became milky due to the polymer network structure formed by the UV irradiation. . Next, the light-shielding frame was removed from the cell surface, and subsequently, the irradiation time setting was changed, and the entire surface of the cell was subjected to second-stage UV irradiation.

The UV irradiation on the cell surface is applied to the liquid crystal / prepolymer mixture composition injected into the cell so that the UV in the photosensitive wavelength range is applied.
The prepolymer component is polymerized by irradiating V light. At the same time, the phase separation between the liquid crystal component and the prepolymer component is advanced to form a polymer network structure made of a UV curable resin inside the cell.

The parameters for the UV irradiation include the UV irradiation method (one-step irradiation, two-step irradiation, etc.)
There are a V wavelength, UV irradiation, UV irradiation time, cell temperature during UV irradiation, a standing time and a leaving environment between one-step irradiation and two-step irradiation in two-step irradiation, and the like.

In the present embodiment, the UV irradiation method, UV illuminance and UV irradiation time were examined as parameters for UV irradiation.

Specifically, a liquid crystal panel was manufactured under the following conditions. In addition, two types of the first stage and the first and second stages described in the present embodiment were manufactured as comparison targets.

(I) In the case of irradiation only in the first stage Illuminance 20 to 150 mW / cm ² Time 0.5 to 120 seconds (ii) In the case of irradiation in the first and second two stages In the first stage, the illuminance 20 to 150 mW / cm ² hours 0.5 to 120 seconds In the second stage, the illuminance 1 to 20 mW / cm ² hours 50 to 3000 seconds During the irradiation, the temperature of the stage is the phase separation temperature of the liquid crystal / prepolymer ( (15-18 ° C) or higher and up to 30 ° C.

The light shielding member 20 serving as the second liquid crystal region
The width between the transparent region and the seal frame is 50 to 300.
The range of 0 μm was studied. In the present embodiment, the boundary portion is 100
The dispersion was about μm. Under these conditions, it was found that if the second liquid crystal region was 200 μm or more, the effect of improving the unevenness was sufficiently exhibited.

The reflectance versus voltage characteristics of the liquid crystal panel obtained in this way were significantly improved in the in-plane distribution, and the display unevenness was reduced to such an extent that there was no practical problem. When the cross section of the polymer network liquid crystal was observed with a scanning electron microscope, a network structure (A indicates a polymer portion, B indicates a liquid crystal portion) schematically shown in FIG. 8 was observed. The average diameter of the holes of the mesh of the polymer in the first region including the display region irradiated with the first and second two-step irradiation is 0.5 to 5 μm, and the average of the second region in only the second step irradiated weakly The diameter is 5-100μ
m.

For example, the first stage irradiation is performed at 40 mW / c.
When the second stage was performed at 5 mW / cm ² for 430 seconds at m ² for 6 seconds, the in-plane luminance unevenness was suppressed to within ± 5%. The effect of the distribution improvement is, for example, 40 mW /
The same effect was observed when the measurement was performed at 60 cm ² for 60 seconds and the second step was not performed. In addition, hysteresis, response speed and contrast were better than before.

The liquid crystal panel according to the present embodiment is denoted by R,
When optimized for each of the G and B colors and set in a three-plate projection type projector, the in-plane distribution of color unevenness was improved, and the quality of image quality was greatly improved.

(6: End Seal of Liquid Crystal Injection Port) The cells irradiated with UV light were subjected to end seal of the liquid crystal injection port.
As the end seal agent, UV curable epoxy acrylate resin 30Y-195B manufactured by Three Bond Co., Ltd. was used. An end sealant was applied to the liquid crystal injection port of the cell to shield the liquid crystal display of the cell from light, and then the end sealant was irradiated with UV and cured by UV to complete the end seal. In addition, as the end seal agent, UV curable allyl resin A704 manufactured by Sekisui Fine Chemical Co., Ltd., Kyoritsu Chemical Sangyo Co., Ltd., etc. could be used. Next, after removing the foreign substances attached to the cell surface, the cell is attached to a holder for mounting an optical system, and furthermore, a flexible printed circuit board is connected to the holder and an active matrix substrate using wire bonding is used to transmit image signals. By connecting the electrode pads to the flexible printed circuit board, a liquid crystal display panel could be formed.

The contrast ratio of the liquid crystal panel thus produced will be described. It was found that in the two-step irradiation, the first-step UV illuminance required was at least 20 mW / cm ² or more. In addition, the first-stage illuminance is 50 mW / c.
When it is set to m ² or more, deterioration of the contrast ratio is not observed in the range up to 120 mW / cm ² . This phenomenon is 1
This is presumably because the size of the polymer network formed became smaller due to the increase in the stepwise illuminance, and the scattering characteristics for the longest wavelength R began to deteriorate.

Accordingly, the upper limit of the first-stage illuminance is determined by the deterioration of the scattering characteristics due to the miniaturization of the polymer network, and it is desirable that the illuminance is substantially 150 mW / cm ² or less.

[Second Embodiment] FIG. 3 is a diagram showing a schematic configuration of a light irradiation apparatus according to a second embodiment of the present invention.

In FIG. 3, reference numeral 11 denotes a light source which is an arc tube such as a metal halide lamp, a halogen lamp, or a xenon lamp; 16, a light shielding mask; 20, a liquid crystal panel including the active matrix substrate 1 and the counter glass 2; A band-pass filter that transmits light through a region, 18 is a condenser lens that collects light in the direction of the liquid crystal panel 20, 19 is a condenser lens that outputs parallel light to the liquid crystal panel 4, and 15 is an xy stage with a temperature adjustment function. .

In this embodiment, as in the first embodiment, a cell in which a glass substrate 2 is bonded to a reflective active matrix substrate 1 via a sealing agent and a spacer agent is produced, and a nematic is added to a polyacrylate polymer. 4: 1 liquid crystal
Was injected at normal pressure.

In this embodiment, the configuration at the time of UV irradiation is shown in FIG.
It was configured as follows. That is, the light source 11 having a peak at a wavelength of 350 to 400 nm is formed using a light shielding mask, and the optical filter (bandpass filter) 17 is used to form the light source 11 at a wavelength of 350 to 400 nm.
Only the components were transmitted, reduced to a desired size by the condenser lenses 18 and 19, and the liquid crystal panel 20 placed on the XY stage 15 with a temperature adjustment function was irradiated with light.

In this system, since the irradiation position can be finely adjusted on the xy stage, the first and second liquid crystal regions can be precisely controlled.

Further, by moving the light-shielding mask 16,
Since the irradiation time can be controlled and the light-shielding area can be changed, the structure is such that two steps of UV irradiation can be performed at once with a single device, contributing to an improvement in productivity.

The UV irradiation conditions were examined in the same range as in the first embodiment. The width of the second liquid crystal region is 50
５5000 μm were studied.

In this embodiment, the light is perpendicularly incident on the panel, and the positional accuracy of the irradiation area is within ± 1 μm. As a result, the effect of improving the unevenness is 100 μm or more and 3000 μm.
m or less.

The reflectance vs. voltage characteristics of the obtained liquid crystal panel 20 were remarkably improved as compared with the prior art, and the display unevenness was eliminated, as in the first embodiment.

Further, characteristics such as contrast, hysteresis, response speed and the like were also higher than those of the prior art.

[0085]

According to the present invention, the first region irradiated with the first and second steps surrounded by the light-shielding member has the second region.
Is used as a stress relaxation layer and the network of the display section is made uniform, thereby preventing display brightness unevenness and improving color unevenness when three colors are combined in a three-panel liquid crystal display device.

Further, according to the present invention, since the second region functions as a layer for alleviating the alignment regulating force from the seal, the effect of the seal on the display region is less likely to occur, and the display luminance unevenness and color unevenness are greatly reduced. Be improved.

Further, by performing the first and second two-step irradiation, all the liquid crystal mixtures are reacted, the instability of the liquid crystal is eliminated, and the reliability of the liquid crystal display device can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual plan view and a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an external view of a liquid crystal display device according to an embodiment of the present invention at the time of irradiation in a manufacturing stage.

FIG. 3 is an external view of a liquid crystal display device according to an embodiment of the present invention during irradiation in a manufacturing stage.

FIG. 4 is a hysteresis characteristic diagram of the liquid crystal display device according to the embodiment of the present invention.

FIG. 5 is a plan view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 6 is a conceptual sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 7 is an external view of an evaluation optical system and a projection type liquid crystal display device of the liquid crystal display device according to the embodiment of the present invention.

FIG. 8 is a diagram schematically illustrating an example of a cross-sectional structure of a liquid crystal layer used in a liquid crystal display device according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 active matrix substrate 2 facing glass 3 sealant 4 spacer 5 display area 6 inlet 7 first area liquid crystal 11 arc tube 12 mirror 13 short wavelength cut filter 14 liquid crystal / prepolymer mixture 15 temperature adjustment stage 16 light shielding mask 17 bandpass Filter 18, 19 Condenser lens 20 Liquid crystal panel

Claims (18)

[Claims] 1. A first polymer-containing liquid crystal region constituting a first region including a display region, and a second polymer-containing liquid crystal region outside the first region.
And a second polymer-containing liquid crystal region constituting a region of the first and second polymer-containing liquid crystal regions,
A liquid crystal display device having a different polymer network structure. 2. The polymer-containing liquid crystal region according to claim 1, wherein the average diameter of the polymer network holes observed by observing a cross section of the polymer-containing liquid crystal region is different between the first and second polymer-containing liquid crystal regions. Liquid crystal display. 3. The liquid crystal display device according to claim 2, wherein the average diameter of the holes in the first polymer-containing liquid crystal region is smaller than that of the second polymer-containing liquid crystal region. 4. The liquid crystal display device according to claim 3, wherein an average diameter of the holes in the first polymer-containing liquid crystal region is in a range of 0.5 to 5 microns. 5. The liquid crystal display device according to claim 3, wherein an average diameter of the holes in the second polymer-containing liquid crystal region is in a range of 5 to 100 microns. 6. The liquid crystal display device according to claim 1, wherein the width of the second polymer-containing liquid crystal region is 100 μm or more. 7. The liquid crystal display according to claim 6, wherein the width of the second polymer-containing liquid crystal region is 200 μm or more. 8. The liquid crystal display device according to claim 1, wherein the second polymer-containing liquid crystal region is in contact with a sealing portion for sealing the polymer-containing liquid crystal.
3. The liquid crystal display device according to 1. 9. The liquid crystal display device according to claim 8, wherein the first polymer-containing liquid crystal region is not in contact with the seal portion and is located inside the second polymer-containing liquid crystal region. 10. A liquid crystal material and a prepolymer material are disposed between a pair of substrates, at least one of which is transparent, and the prepolymer material is polymerized by irradiating light that causes a polymerization reaction to the prepolymer material. In the method of manufacturing a liquid crystal display device configured by the above, after irradiating the first region including the display region with the first light,
A method for manufacturing a liquid crystal display device, comprising: irradiating a second region outside the first region and the first region with second light. 11. The method according to claim 10, wherein the first region is located inside a sealing region for sealing a liquid crystal material. 12. The method according to claim 11, wherein the second area includes the seal area. 13. The method according to claim 10, wherein the light irradiation is performed using ultraviolet light. 14. The method according to claim 13, wherein the first light irradiation has a higher illuminance than the second light irradiation. 15. The first light irradiation is performed at 20 to 150 mW.
/ Cm ^{2 at} an illuminance of 2 to 20 m.
The method for manufacturing a liquid crystal display device according to claim 10, wherein the illuminance is W / cm ² . 16. The method according to claim 1, wherein the first light irradiation has a shorter irradiation time than the second light irradiation.
4. The method for manufacturing a liquid crystal display device according to item 3. 17. The method according to claim 16, wherein the first light irradiation is performed for 0.5 to 120 seconds, and the second light irradiation is performed for 50 to 3000 seconds. 18. A liquid crystal for displaying an image by irradiating the liquid crystal display device according to claim 1 with light from a light source and projecting the reflected light from the liquid crystal display device on a screen. projector.