JPH09251103A - Microlens sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a microlens sheet which can be easily produced and can be used to enlarge the visual field angle of a liquid crystal display by constituting the sheet of a mesh sheet and an optically transparent resin formed in the openings of the mesh sheet in such a manner that the resin in the mesh opening is formed into a concave lens state. SOLUTION: A mesh sheet 2 is applied on a transparent substrate 1 and an optically transparent resin 3 is formed in the openings of the mesh sheet 2 so that the resin in the opening of the mesh is formed into a concave lens. The opening rate of the mesh sheet 2 is preferably >=50% considering the brightness when the sheet is attached to a display, and more preferably, >=60%. The mesh is preferably 100 to 600 mesh considering the visibility and light transmitting property for a display. The microlens sheet is produced by covering a transparent substrate 1 with a mesh sheet 2, applying a polymerizable compd. or a compsn. containing the compd. on the mesh sheet 2 to impregnate, and then polymerizing the polymerizable compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens sheet used for liquid crystal displays and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a means for enlarging the viewing angle of a liquid crystal display, it has been proposed to dispose an optical element such as a microlens sheet on the observer side of the liquid crystal display. Examples of mounting the microlens sheet include a combination of a light guide plate and a scattering plate in which microbeads are arrayed in a matrix (Japanese Patent Laid-Open No. 5-196927), and two one-dimensional microlens sheets are combined so as to be orthogonal to each other. (Japanese Patent Application Laid-Open No. 7-43704), transparent microbeads arranged on the surface of a transparent plate at high density (Japanese Patent Application Laid-Open No. 7-72469), and a thin slice of a bundle of many optical fibers ( JP-A-7-72
No. 471) and the like are known.

[0003]

In manufacturing the above-mentioned microlens sheet, a manufacturing technique of microbeads having a uniform diameter is essential (Japanese Patent Laid-Open No. 5-196927,
There is a problem that the number of steps is increased for strictly controlling the structure, such as JP-A-7-72469) or a method requiring a lithography step. An object of the present invention is to provide a microlens sheet which can be used for widening the viewing angle of a liquid crystal display and can be easily manufactured.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that a mesh sheet and an optically transparent resin formed in the openings of the mesh sheet are used. The present inventors have found that the microlens sheet can be easily manufactured and can be used for widening the viewing angle of a liquid crystal display, and thus completed the present invention.

That is, the present invention is as follows. (1) A microlens sheet comprising a mesh sheet and an optically transparent resin formed in the openings of the mesh sheet, and the resin shape of the mesh openings is a concave lens shape. (2) Attaching a mesh sheet on a transparent substrate, coating and impregnating the mesh sheet with at least one polymerizable compound or a composition containing the polymerizable compound, and then polymerizing the polymerizable compound. A method of manufacturing a microlens sheet, characterized by: (3) A transparent substrate is coated with at least one polymerizable compound or a composition containing the polymerizable compound, and then a mesh sheet is attached thereon to form the polymerizable compound or the composition containing the polymerizable compound. A method for producing a microlens sheet, comprising the steps of impregnating a mesh sheet with an object and then polymerizing the polymerizable compound.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. FIG. 1 is an enlarged sectional view of the microlens sheet of the present invention. The mesh sheet 2 is attached on the transparent substrate 1, the optically transparent resin 3 is formed in the opening of the mesh sheet, and the resin shape of the mesh opening is a concave lens shape.

The transparent substrate in the present invention is not particularly limited as long as it is optically transparent. For example, glass or plastic film can be used. The microlens sheet of the present invention is used together with a transparent substrate used at the time of manufacture or after peeling the transparent substrate. Further, the microlens sheet may be directly provided on the polarizing plate or the like.

The aperture ratio of the mesh sheet is preferably 50% or more, more preferably 60% or more, from the viewpoint of brightness when mounted on a display. The size of the opening of the mesh sheet is appropriately selected according to the application. For example, when it is used for expanding the viewing angle of a liquid crystal display, it is selected according to the size of the pixel of the liquid crystal cell to be mounted. From the point of viewability and light transmission of the display, 100-
It is preferably 600 mesh.

Further, as the mesh-like sheet, it is preferable to use those having substantially the same area of each opening in order to exhibit the performance as a microlens sheet. As a method for obtaining a mesh sheet having a substantially constant opening area, a method of weaving fibers, a method of printing a lattice by screen printing, etc. can be mentioned, but a method of weaving fibers is preferable from the viewpoint of easy production. . In this case, the material of the fibers used is not particularly limited, but examples thereof include natural fibers such as cotton, hemp, and silk, synthetic fibers such as polyamide, polyester, and polypropylene, metal fibers such as stainless steel, and glass fibers. Natural fibers and synthetic fibers are preferably used because they are easily available and easy to handle.
When a fiber is used, its yarn diameter is determined by the balance between the pitch of the openings of the mesh sheet and the aperture ratio, but when it is attached to a liquid crystal display, it is 100 μm or less from the viewpoint of screen visibility. Is preferable, and more preferably 60 μm or less.

The resin to be formed in the openings of the mesh sheet is not particularly limited as long as it is optically transparent, and at least one polymerizable compound or a composition containing the polymerizable compound ( Hereinafter, it will be simply referred to as a polymerizable compound). The polymerizable compound includes a prepolymerized polymerizable compound. These polymerizable compounds may be used by mixing two or more kinds thereof or by adding a reactive or non-reactive third component such as a polymerization initiator or a solvent in order to adjust the viscosity within a preferable range. .

Since the microlens sheet of the present invention utilizes the fact that the resin takes a meniscus shape at the opening of the mesh sheet, the viscosity of the polymerizable compound impregnated into the mesh sheet before polymerization is compared. It is desirable to use the one that is extremely low. The viscosity of the polymerizable compound when impregnated is preferably 5 Pa · s or less, more preferably 3 P.
It is a · s or less. By impregnating while heating,
You may use it, after reducing the viscosity of a polymeric compound to a preferable value.

The surface of the resin formed in the openings of the mesh sheet takes a meniscus shape as shown in FIG. 1 by impregnating the mesh sheet with a polymerizable compound satisfying the above-mentioned conditions and polymerizing it to form a concave lens. To work.
When the viscosity of the polymerizable compound is higher than 5 Pa · s, the surface of the resin portion of the opening is unlikely to have a meniscus shape when impregnated in the mesh sheet, and the obtained sheet may not show sufficient concave lens characteristics.

The method of impregnating the mesh sheet with the polymerizable compound is not particularly limited, and a known method can be used. A method of impregnating a mesh sheet in a state of being fixed on a transparent plate, or after applying a polymerizable compound to a substrate in advance by a known method, and then attaching a mesh sheet to the polymerizable sheet to form a mesh of the polymerizable compound. Examples include a method of impregnating a sheet.
If the amount of the polymerizable compound to be impregnated is too large, the polymerizable compound exudes from the surface of the sheet, which makes it difficult to form the resin shape of the opening in the meniscus shape. In the case of the latter method, the coating thickness of the polymerizable compound is preferably not more than the thickness of the mesh sheet.

After impregnating the mesh sheet with the polymerizable compound, it is necessary to fix the meniscus shape of the openings of the mesh sheet. Examples of the method of fixing the meniscus shape include a method of impregnating a polymerizable compound and then polymerizing the polymerizable compound, and a method of heating and impregnating and then fixing the shape by cooling. The former method is more preferably used from the viewpoint of ease of production and durability of the obtained sheet.

The method for polymerizing the polymerizable compound is U
Examples of the method include a method of curing an energy ray such as V or an electron beam or a thermosetting resin. Energy ray curing is a more preferable method from the viewpoint of stably maintaining the meniscus shape formed during impregnation during the polymerization reaction.

The energy ray-curable polymerizable compound is not particularly limited as long as the viscosity of the mesh sheet under the conditions of impregnation is within the above range, but a more preferable example is a polymerizable compound having a (meth) acrylate group. Is mentioned. Examples of the polymerizable compound include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate. , Glycerin tri (meta)
Acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tetra (meth) acrylate
Acrylate, tripentaerythritol penta (meth) acrylate, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di ( Poly (meth) acrylates of polyhydric alcohols such as (meth) acrylate, tripentaerythritol hexa (meth) acrylate or hexamethacrylate, tripentaerythritol hepta (meth) acrylate,
Malonic acid / trimethylolethane / (meth) acrylic acid, malonic acid / trimethylolpropane / (meth) acrylic acid, malonic acid / glycerin / (meth) acrylic acid,
Malonic acid / pentaerythritol / (meth) acrylic acid, succinic acid / trimethylolethane / (meth) acrylic acid, succinic acid / trimethylolpropane / (meth) acrylic acid, succinic acid / glycerin / (meth) acrylic acid, succinic acid Acid / pentaerythritol / (meth) acrylic acid, adipic acid / trimethylolethane / (meth) acrylic acid, adipic acid / trimethylolpropane / (meth) acrylic acid, adipic acid / pentaerythritol /
(Meth) acrylic acid, adipic acid / glycerin / (meth) acrylic acid, glutaric acid / trimethylolethane /
(Meth) acrylic acid, glutaric acid / trimethylolpropane / (meth) acrylic acid, glutaric acid / glycerin /
(Meth) acrylic acid, glutaric acid / pentaerythritol / (meth) acrylic acid, sepacic acid / trimethylolethane / (meth) acrylic acid, sepacic acid / trimethylolpropane / (meth) acrylic acid, sepacic acid / glycerin / ( (Meth) acrylic acid, cepaic acid / pentaerythritol / (meth) acrylic acid, fumaric acid / trimethylolethane / (meth) acrylic acid, fumaric acid / trimethylolpropane / (meth) acrylic acid, fumaric acid / glycerin / (meth ) Acrylic acid, fumaric acid / pentaerythritol / (meth) acrylic acid, itaconic acid / trimethylolethane / (meth) acrylic acid, itaconic acid / trimethylolpropane / (meth) acrylic acid, itaconic acid / pentaerythritol / (meth) ) Acrylic acid, maleic anhydride / tri Chiroruetan / (meth) acrylic acid, a saturated or unsaturated polyester poly (meth) acrylate with a combination of compounds, such as maleic acid / glycerol / (meth) acrylic acid anhydride, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate,
Hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, or diisocyanate compounds obtained by hydrogenating aromatic isocyanates among these diisocyanate compounds (for example, diisocyanate compounds such as hydrogenated xylylene diisocyanate and hydrogenated diphenylmethane diisocyanate), triphenylmethane triisocyanate (Meth) acrylic monomers having an active hydrogen and an isocyanate-containing compound such as a polyisocyanate compound obtained by polymerizing a divalent or trivalent polyisocyanate compound such as isocyanate or dimethylenetriphenyltriisocyanate, or a diisocyanate compound, For example, 2-hydroxyethyl (meth)
Urethane obtained by reacting acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-methoxypropyl (meth) acrylate, N-methylol (meth) acrylamide, etc. in an amount of 2 mol or more per 1 molecule of isocyanate by a conventional method. Examples include epoxy (meth) acrylates such as (meth) acrylate, tri (meth) acrylate of tris (2-hydroxyethyl) isocyanuric acid, bisphenol A derivative, bisphenol F derivative, and bisphenol S derivative.

In order to improve the curability of the polymerizable composition,
It is preferable to use a photopolymerization initiator, and as the photopolymerization initiator, for example, benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, diethoxyacetophenone, benzyl dimethyl ketal, Two
-Hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone and the like can be mentioned.

In the microlens sheet of the present invention, in order to reduce the scattering at the mesh portion and the resin interface and suppress the reflected light, the material for forming the mesh sheet and the resin have almost the same refractive index, or the mesh has a mesh shape. The sheet-like sheet may be coated or dyed with a light-shielding substance such as a light-shielding pigment or dye. Covering or dyeing the mesh sheet with a light-shielding substance is a preferable method from the viewpoint of blocking light from an oblique direction which causes deterioration of image quality when the sheet is mounted on a liquid crystal panel.

[0019]

The microlens sheet of the present invention utilizes the fact that the surface of the resin formed in the openings by polymerizing the mesh sheet by impregnating the polymerizable compound has a meniscus shape. The focal length of the lens can be more easily controlled by the size of the mesh of the sheet, the viscosity of the polymerizable compound, the refractive index, the impregnation condition, etc., and the microlens sheet can be manufactured more easily than the conventional method using photolithography or the like. be able to. Further, since the microlens sheet of the present invention has a function of spreading incident light to the wide angle side, it is effective for expanding the viewing angle of a liquid crystal display.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The measuring methods used in the examples are as follows. (1) Measurement of surface shape: needle contact type surface roughness meter (TOKYO
The surface shape of the sample was measured using SEIMITSU Surfcom 30C type). (2) Measurement of outgoing light scattering angle width: The scattering intensity angular distribution of outgoing light when white parallel light was incident on the sample was measured as shown in FIG. 2 using a Goniophotometer manufactured by Murakami Institute of Technology.

Example 1 A 200-mesh colored black woven polyester fabric having a thread diameter of 32 μm and an aperture ratio of 56% was fixed on a glass substrate with an adhesive, and then the acrylate group-containing polymerizable resin was placed on the woven fabric. Acrylate-based hard coating agent (Kouei Hard M101, resin content: about 80%, viscosity: 0.2 Pa)
S, manufactured by Koei Chemical Co., Ltd., was applied with a glass rod, impregnated into a woven fabric, and air-dried at room temperature for about 20 minutes. After that, ultraviolet rays were irradiated using a high pressure mercury lamp until the integrated light amount reached 0.5 J / cm ² , to polymerize the polymerizable compound.

As a result of observing the surface shape of the obtained microlens sheet, it was confirmed that the resin portion of the opening had a concave lens shape. When parallel light was incident from the glass substrate side of the microlens sheet, the emitted light was about ± 3
It was confirmed that it has a function of expanding the range to 0 °.

Example 2 A microlens sheet was prepared in the same manner as in Example 1 except that a polyester woven cloth having a black colored 140 mesh, a thread diameter of 32 μm and an opening ratio of 68% was used. As a result of observing the surface shape of the obtained microlens sheet, it was confirmed that the resin portion of the opening had a concave lens shape. When parallel light was made incident from the glass substrate side of the microlens sheet, it was confirmed that it has a function of expanding the emitted light to a range of about ± 40 °.

Example 3 A bar coater (manufactured by Yoshimitsu Seiki Co., Ltd., # 1) was prepared by using the same acrylate-based hard coating agent used in Example 1.
2. Mandrel and winding material: SUS-304, winding diameter:
0.30 mm) was used for coating on a glass substrate. After air-drying at room temperature for about 20 minutes, the same mesh sheet as that used in Example 1 was attached and polymerization was carried out in the same manner as in Example 1. When parallel light was made incident from the glass substrate side of the obtained microlens sheet, it was confirmed that it has a function of expanding the emitted light to a range of about ± 30 °. Further, when parallel light was incident from the UV irradiation surface side of the microlens sheet, it was confirmed that it has a function of expanding the emitted light to a range of about ± 50 °.

Comparative Example 1 When parallel light was incident on a glass sheet on which only the mesh sheet used in Example 1 was attached, the effect of spreading parallel light to the wide angle side was not recognized.

Comparative Example 2 As a polymerizable compound having an acrylate group, 100 parts of an epoxy acrylate (NK ester 530A, viscosity at 20 ° C. is 10 Pa · s or more, manufactured by Shin-Nakamura Chemical Co., Ltd.) was added to an acetophenone photoinitiator (Darocur 1173). , Manufactured by Merck & Co., Inc.)
I went the same way. As a result of observing the surface shape of the obtained sheet, the resin portion of the opening was almost flat and did not have a concave lens shape. Parallel light was incident on the sheet, but there was no function to spread the emitted light.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a microlens sheet of the present invention.

FIG. 2 is a diagram showing a concept of measuring a scattering angle width.

[Explanation of symbols]

 1 transparent substrate 2 mesh sheet 3 resin

Claims (7)

[Claims] 1. A microlens sheet comprising a mesh sheet and an optically transparent resin formed in the openings of the mesh sheet, wherein the mesh openings have a concave lens shape. 2. The microlens sheet according to claim 1, wherein the mesh of the mesh sheet is 100 to 600 mesh. 3. The microlens sheet according to claim 1, wherein the mesh sheet is coated or dyed with a light-shielding substance. 4. The microlens sheet according to claim 1, wherein the optically transparent resin is a resin obtained by polymerizing at least one polymerizable compound. 5. A transparent sheet is provided with a mesh sheet, and the mesh sheet is coated with and impregnated with at least one polymerizable compound or a composition containing the polymerizable compound, and then the polymerizable compound is polymerized. A method of manufacturing a microlens sheet, comprising: 6. A transparent substrate is coated with at least one polymerizable compound or a composition containing the polymerizable compound, and then a mesh sheet is attached onto the transparent compound to deposit the polymerizable compound or the polymerizable compound. A method for producing a microlens sheet, comprising impregnating a composition containing the composition into a mesh sheet and then polymerizing the polymerizable compound. 7. The production method according to claim 5, wherein the viscosity of the polymerizable compound at the time of impregnation or the composition containing the polymerizable compound is 5 Pa · s or less.