JP3401720B2 - Light diffusion reflector for reflective liquid crystal display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffuse reflection plate used in a reflection type liquid crystal display device which does not require a backlight. [0002] Liquid crystal displays (hereinafter abbreviated as LCDs)
Utilizing features such as thinness, small size, and low power consumption, is currently used for display units such as watches, calculators, TVs, and personal computers. In recent years, color LCDs have been developed and OA / AV
It is beginning to be used for many purposes, such as navigation systems, viewfinders, and personal computer monitors, mainly for equipment, and the market is expected to expand rapidly in the future. In particular, reflective LCDs that perform display by reflecting light incident from the outside are attracting attention as portable terminal equipment because they do not require a backlight, consume less power, and can be made thinner and lighter. ing. Conventionally, a reflection type LCD employs a twisted nematic system and a super twisted nematic system. In these systems, however, half of the incident light is not used for display by a linear polarizer, and the display becomes dark. turn into. Therefore, the number of polarizers was reduced to one, and a method combined with a retardation plate or a phase transition type guest
A host display mode has been proposed. In order to obtain a bright display by efficiently using external light in a reflective LCD, it is necessary to further increase the intensity of light scattered in a direction perpendicular to the display screen with respect to incident light from all angles. There is. Therefore, it is necessary to control the reflection film on the reflection plate so as to obtain appropriate reflection characteristics. A method in which a photosensitive resin is applied to a substrate and patterned using a photomask to form irregularities, and a metal thin film is formed to form a diffuse reflection plate (Japanese Patent Laid-Open No. 4-2432).
No. 26) has been proposed. [0005] The diffuse reflection plate of the reflection type LCD is controlled by using a resin for a base layer having an uneven shape in order to form unevenness of a diffuse reflection film for effectively diffusing external light. The unevenness is formed, and a metal thin film is laminated and manufactured. At this time, the controlled uneven shape involves a predetermined step to improve the utilization efficiency of the external light. Further, in order to form a reflective LCD, there is a predetermined step in the diffuse reflection plate alone.
A uniform cell gap cannot be obtained. For this reason,
An overcoat layer is laminated on the metal thin film of the diffuse reflection plate for planarization. When a material having a flattening ability is used for the color filter layer, the color filter layer can be laminated on the metal thin film of the diffuse reflection plate to achieve flattening. In the case of a twisted nematic liquid crystal display device, if the predetermined step due to the uneven shape of the diffuse reflector is a sufficient step to obtain good display, a color filter layer is formed on the metal thin film of the diffuse reflector. They may be stacked. The steps performed after forming the metal thin film of the diffuse reflection plate include a step of forming a transparent electrode for driving the LCD, a step of forming an alignment film for performing liquid crystal alignment of the LCD, After lamination, curing of the seal part,
There is a step of injecting a liquid crystal material and the like. Each of the above steps generally involves a heat treatment. The heat treatment has an effect of promoting the release of gas contained in the base resin layer. At this time, if the underlayer resin is covered and covered by the metal thin film, holes may be formed in the metal thin film when gas is released from the resin. Will open. This hole becomes a defect of the LCD, which is not preferable. If a material that emits less gas is used for the base resin layer, it is possible to suppress hole defects in the metal thin film due to gas emission, but the material that emits less gas will have unevenness in the diffuse reflection film that effectively diffuses external light. Will result in a material such as an inorganic material that cannot form a solid. By releasing the gas contained in the base resin layer before forming the metal thin film, it is possible to suppress hole defects in the metal thin film due to gas release. The gas is adsorbed from the air or the like from the pinhole of the thin film or the end face of the substrate over time. For this reason, if the LCD manufacturing process is long, gas is adsorbed, and it is not possible to eliminate hole defects in the metal thin film. In order to suppress the hole defect of the metal thin film, the LCD manufacturing process can be completed in a short time or the characteristics may be deteriorated.
Optimization with other materials was required so that each heat treatment in the CD manufacturing process could be performed at a low temperature. The present invention provides a diffuse reflection plate for a reflection type liquid crystal display, which has good reflection characteristics and prevents defects due to gas emission in an LCD manufacturing process. According to the present invention, there is provided a light diffusing reflector for a reflection type liquid crystal display according to the present invention, in which an undercoat resin layer and a metal reflection film layer having an uneven shape are laminated , and an overcoat layer or a color filter is further formed.
It is a light diffusion reflector with a built-in cell for reflection type liquid crystal display with a filter layer laminated.
In a reflection type liquid crystal display device having a film process , holes having a size of 30 μm or less are formed at an interval of 2 mm or less and at an area ratio of 0.08% or more in a metal reflection film layer formation surface.
A light diffusion reflector for a reflection type liquid crystal display, wherein a region without a metal reflection film layer is provided on a base or groove-like base resin layer . According to the present invention, by providing a region having no metal reflective film layer on the base resin layer in advance, it is possible to prevent hole defects in the metal thin film due to gas release from the base resin layer having an uneven shape due to heat treatment in an LCD manufacturing process. Things. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A light diffusion reflector for a reflection type liquid crystal display of the present invention uses a base resin layer having an uneven shape. The surface shape of the irregularities is not particularly limited, but may be not only a complex plane but also a concave or convex curved surface, a curved surface of a complex irregularity, and further a concave or convex curved surface approximating a spherical surface or a parabolic surface, a curved surface of a complex irregularity. preferable. By making the surface curved, diffused light from a wide range of light source positions can be expected. In particular, in the case of a light-diffusing reflector for a reflection-type liquid crystal display, it is necessary to form a light-diffusing surface in the LCD cell. Therefore, the average height difference H is preferably as small as possible in consideration of the cell gap and Δnd. As the uneven shape, the height difference between the concave portion and the convex portion is 0.1 to 15 μm, further, 0.1 to 5 μm, the pitch of the convex portion is 0.7 μm or more and 150 μm or the smaller of the pixel pitch, whichever is smaller, Further, it is preferable that the thickness be 2 μm or more and 150 μm or the smaller of the pixel pitch. It is preferable to use an organic composition as the base resin layer of the light diffusion reflector for the reflection type liquid crystal display of the present invention. Such an undercoat resin layer can be coated on a support and cured by actinic rays or heat to form a thin film having a thickness of 0.1 to 15 μm.
An organic composition obtained by curing a negative photosensitive resin composition, a positive photosensitive resin composition, or a thermosetting resin composition by actinic rays, heat, or actinic rays and heat is used. As the base resin layer, for example, polyethylene, polyolefins such as polypropylene, ethylene and vinyl acetate, ethylene and acrylate, ethylene copolymers such as ethylene and vinyl alcohol, polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, Copolymers of vinyl chloride and vinyl alcohol, polyvinylidene chloride, polystyrene, styrene copolymers such as styrene and (meth) acrylate, polyvinyl toluene, vinyl toluene such as vinyl toluene and (meth) acrylate At least one selected from polymers, poly (meth) acrylates, copolymers of (meth) acrylates such as butyl (meth) acrylate and vinyl acetate, synthetic rubbers, cellulose derivatives and the like Organic polymers can be used A photoinitiator, a monomer having an ethylenic double bond, or the like can be added, if necessary, for curing after forming the unevenness. If necessary, dyes, organic pigments, inorganic pigments, powders, and composites thereof may be used alone or in combination. The thickness of these underlying resin layers,
The dielectric constant, hardness, refractive index, and spectral transmittance are not particularly limited. These base resin layers may have a function as a support. These base resin layers may be a laminate of an organic composition. As the metal reflection film layer of the light diffusion reflection plate for a reflection type liquid crystal display of the present invention, a film provided with a metal film that reflects visible light is used. As the metal, for example, aluminum or silver can be used as a main component. The metal does not need to be a single element, and an alloy or a laminated film can be used to suppress hillocks and migration. Further, for the purpose of increasing the reflectance of the metal and protecting the metal, metal oxides such as silicon oxide, alumina, titanium oxide and ITO, metal nitrides such as silicon nitride, SiAl
One or more layers of metal oxynitride such as ON can be laminated on a metal and used as a metal reflective film layer. Further, in order to increase the adhesive strength between the metal and the base resin layer, metal oxides such as silicon oxide, alumina, titanium oxide, and ITO, metal nitrides such as silicon nitride, and metal oxynitrides such as SiAlON are used for the metal and base resin. One or more layers can be laminated between the layers and used as a metal reflective film layer. The method of forming the metal reflection film layer is plating, vacuum deposition, sputtering, CV
D, anodic oxidation and the like. The thickness of the metal reflection film layer is 0.0
1 μm to 50 μm is preferred. In the light diffusion reflector for a reflection type liquid crystal display of the present invention, the region without the metal reflection film layer is formed by photolithography,
A method of removing by polishing or the like is used. Alternatively, a method of selectively forming a film by plating or the like and obtaining a region without a metal reflective film layer as a result is used. 2m without metal reflective layer
m. For example, when the distance between pixels is 2 mm or less, a region without a metal reflective film layer is formed for each pixel. Alternatively, a region without a metal reflection film layer is formed at random so that there is no deviation in the plane. The area without the metal reflection film layer is provided at a rate of 0.08% or more in area ratio.
For example, when the size of each pixel is 100 μm × 300 μm, the area without the metal reflective film layer in each pixel is 24 μm.
² (4.9 μm square) or more. A region without a metal reflection film layer may be formed continuously. For example, a region without a metal reflective film layer having a width of 5 μm is continuously formed on the side of the pixel. In addition, an area without a metal reflection film layer is provided without impairing the aperture ratio of a pixel by providing an area without a metal reflection film layer in a peripheral portion of a pixel and forming an area not used for display between pixels. Can be. As the region without the metal reflection film layer, a hole having a diameter of 30 μm or less
It is preferable that the groove shape is not more than μm. In addition, if the area without the metal reflective film layer is larger than 30 μm, a visual defect is caused. If a region without a metal reflective film layer is formed at an interval exceeding 2 mm or an area ratio of less than 0.08% of the metal reflective film layer forming region on the panel display surface, hole defects in the metal thin film due to gas release are caused. And the ability to suppress cracks is not sufficiently obtained, resulting in a hole defect. [0009] In order to provide the base resin layer with an uneven shape,
The concave and convex shape can be manufactured by pressing the base resin layer against a transfer original plate formed by engraving, etching, etc., transferring the concave and convex shape, and curing and peeling so that the shape can be maintained. it can. In addition, the uneven shape can be transferred from the transfer original plate to the film, and the base resin layer can be pressed and transferred onto the uneven shape forming surface of the film. In this case, the same concavo-convex shape as the transfer master is transferred. Hereinafter, the present invention will be described in detail with reference to examples. (Example 1) A base resin layer forming solution having a thickness of 2 µm was obtained by spin coating the following solution for forming a base resin layer on a glass substrate.
Next, a matte-processed Tetron film mat product PS1
The substrate temperature is 90 ° C. and the roll temperature is 80 using a laminator (roll laminator HLM1500, trade name of Hitachi Chemical Technoplant Co., Ltd.) so that the uneven surface of the sand blast surface is in contact with the base resin layer.
° C., a roll pressure of 0.7MPa (7kg / cm ^2), was laminated at a speed 0.5 m / min, the base resin layer on a glass substrate to obtain a substrate which Tetron film is laminated. next,
After exposure to H-rays at 100 mJ by a high-pressure mercury lamp, the tetron film was peeled off to obtain a base resin layer on which a surface having irregular irregularities was transferred onto a glass substrate. This was thermally cured at 230 ° C. for 30 minutes in an oven, and an aluminum thin film was laminated to a thickness of 0.2 μm by a vacuum deposition method to form a metal reflective film layer. Next, a resist AZ-TFP210K (trade name, manufactured by Hoechst) was spin-coated on the metal reflective film layer and dried on a hot plate at 90 ° C. for 4 minutes to form a resist layer having a thickness of 1.2 μm. A photomask in which 10 μm transparent partial stripes were cut at a pitch of 100 μm was superimposed on this, exposed to H-rays at 60 mJ by a high-pressure mercury lamp, and immersed in a 0.6% by weight aqueous potassium hydroxide solution at 20 ° C. for 160 seconds. The resist was developed. At this stage, the resist on the aluminum thin film is a film in which a filmless groove having a width of 10 μm is formed at a pitch of 100 μm. This was immersed in a 1.0% by weight aqueous sodium hydroxide solution at 20 ° C. for 140 seconds to remove the aluminum thin film by etching so as to form a stripe having a pitch of 100 μm and a width of 10 μm. At this time, the resist is also etched at the same time, but it does not reach the point where the film disappears. Next, the substrate was immersed in acetone, and the resist was peeled off to obtain light diffusion reflection for a reflective liquid crystal display having a region without a metal reflective film layer. An overcoat (HP2000; trade name, manufactured by Hitachi Chemical Co., Ltd.) was applied to the obtained reflection plate.
Spin coat to a thickness of μm
Thermal curing was performed at 0 ° C. for 30 minutes. The flattened light diffusion reflector thus obtained was a light diffusion reflector for a reflective liquid crystal display having good reflection characteristics and no defects and high flatness. Solution for forming base resin layer: styrene, methyl methacrylate, ethyl acrylate as polymer
Acrylic acid and glycidyl methacrylate copolymer resin were used (polymer A). The molecular weight is about 35,000 and the acid value is 110. Parts are parts by weight (the same applies hereinafter). (Polymer) Polymer A 70 parts (monomer) Pentaerythritol tetraacrylate 30 parts (photoinitiator) Irgacure 369 (Chiba Specialty Chemicals) 2.2 parts N, N-tetraethyl-4,4'-diaminobenzophenone 2.2 Parts (solvent) Propylene glycol monomethyl ether 492 parts (polymerization inhibitor) p-methoxyphenol 0.1 part (surfactant) Perfluoroalkyl alkoxylate 0.01 part (Example 2) Implemented on a glass substrate The same base resin layer forming solution as in Example 1 was spin-coated to obtain a base resin layer having a thickness of 2 μm. Next, a laminator (roll laminator HLM1500, trade name, manufactured by Hitachi Chemical Technoplant Co., Ltd.) is used to process the matte-processed Tetron film mat product PS1 (trade name, manufactured by Teijin Limited) so that the uneven surface of the sandblast surface contacts the base resin layer. Substrate temperature 90 ° C, roll temperature 80 ° C, roll pressure 0.7MPa using
(7 kg / cm ² ) at a speed of 0.5 m / min to obtain a substrate having a base resin layer and a tetron film laminated on a glass substrate. Next, H
After exposure of 100 mJ with a line, the tetron film was peeled off,
A base resin layer having a surface with irregular irregularities transferred onto a glass substrate was obtained. This was thermally cured at 230 ° C. for 30 minutes in an oven, and an aluminum thin film was laminated to a thickness of 0.2 μm by a vacuum deposition method to form a metal reflective film layer. Next, a resist AZ-TFP is formed on the metal reflective film layer.
Spin coat 210K (trade name, manufactured by Hoechst) and 90
It was dried on a hot plate at 4 ° C. for 4 minutes to form a resist layer having a thickness of 1.2 μm. On this, a transmission hole of 5 μm square has a pitch of 100 μm in the X direction and 300 μm in a Y direction perpendicular to the X direction.
A photomask cut at a pitch was overlaid, exposed to H-rays at 60 mJ by a high-pressure mercury lamp, and immersed in a 0.6% by weight aqueous potassium hydroxide solution at 20 ° C. for 160 seconds to develop the resist. At this stage, the resist on the aluminum thin film has a 5 μm square filmless hole having a pitch of 100 μm in the X direction.
The film is formed with a pitch of 300 μm in the m and Y directions. This was immersed in a 1.0% by weight aqueous sodium hydroxide solution at 20 ° C. for 140 seconds, and a 5 μm square hole was formed in the aluminum thin film at a pitch of 100 μm in the X direction and 300 μm in the Y direction.
Was removed by etching. At this time, the resist is also etched at the same time, but it does not reach the point where the film disappears. Next, the substrate was immersed in acetone, and the resist was peeled off to obtain light diffusion reflection for a reflective liquid crystal display having a region without a metal reflective film layer. An overcoat (HP2000; trade name, manufactured by Hitachi Chemical Co., Ltd.) was applied to the obtained reflection plate.
Spin coat to a thickness of μm
Thermal curing was performed at 0 ° C. for 30 minutes. The flattened light diffusion reflector thus obtained was a light diffusion reflector for a reflective liquid crystal display having good reflection characteristics and no defects and high flatness. (Comparative Example 1) A base resin layer having a surface with irregular irregularities was obtained on a glass substrate in the same manner as in Example 1. Then, heat curing was performed in an oven at 230 ° C. for 30 minutes in the same manner as in Example 1, and an aluminum thin film was laminated on the surface to a thickness of 0.2 μm by a vacuum evaporation method to form a reflective layer. In the steps so far, all the irregularities are covered with the aluminum thin film. An overcoat (HP2000; trade name of Hitachi Chemical Co., Ltd.) is applied to this light diffusion reflector.
Was spin-coated so as to have a thickness of 2 μm, and thermally cured in an oven at 230 ° C. for 30 minutes. The obtained flattened light diffusion reflector had a plurality of protruding defects, and was difficult to use as a reflection LCD diffusion reflector. According to the light diffusing reflector for a reflection type liquid crystal display of the present invention, since a region without a metal reflection film layer is provided in a surface on which a metal reflection film layer is formed, a gas is produced in an LCD manufacturing process. A defect due to emission can be prevented, and a diffuse reflector having good reflection characteristics can be efficiently manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a light diffusion reflector for a reflective liquid crystal display of the present invention. FIG. 2 is a cross-sectional view of a reflective LCD. [Explanation of Codes] 1. glass substrate 2. reflective film 3. base resin layer Anti-glare film5. 5. Pixel electrode 6. Thin film transistor Alignment film 8. Liquid crystal layer9. Spacer 10. Retardation film 11. Polarizer

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Nobuaki Takane 48 Wadai, Tsukuba, Ibaraki Hitachi Chemical Industry Co., Ltd. Within the Research Institute (56) References JP-A-6-167708 (JP, A) JP-A-7-98452 (JP, A) JP-A-7-134300 (JP, A) JP-A-2000-47207 (JP, A) JP-A-2000-284275 (JP, A) JP-A-2001-83538 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1335 520 G02B 5/02 G02B 5/08

Claims (1)

(57) [Claims 1] An uneven base resin layer and a metal reflective film layer are laminated , and an overcoat layer or a color filter is further formed.
A light diffusion reflector with a built-in cell for a reflective liquid crystal display with stacked layers , and a process for forming a transparent electrode and forming an alignment film.
In the reflection type liquid crystal display device having the above , in the metal reflection film layer forming surface, at an interval of 2 mm or less and at an area ratio of 0.0
Holes and grooves with a size of 30 % or less with a ratio of 8% or more
A light diffusion reflector for a reflection type liquid crystal display, wherein a region without a metal reflection film layer is provided on the base resin layer.