JPH05158153A - Lens sheet - Google Patents

Abstract

PURPOSE:To provide a lens sheet which does not generate such reflected light that a ghost is formed thereby in the rear of the transmission type screen of a video projection TV and is excellent in productivity. CONSTITUTION:A Fresnel lens 2 wherein a video picture is projected from the rear is formed in a lens sheet. The rear 3 having an unevenly shaped face of the lens sheet is constituted of a roughened face which has many unevennesses difficult to generate regularly reflected light or of a lenticular lenslike structure. Therefore, since light is emitted from a projection source, reflected by a reflecting mirror, and the light reached the rear of the screen is scattered on the roughened face of the unevenness face 3, a ghost is not generated. The ghost is not generated because reflected light is returned to a reflective surface and again reflected. Further, when the roughened face is made lenticular lenslike, the angle of a visual field in the vertical direction is enhanced which is even the large subject of a present video projection TV.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens sheet used for a screen of a video projection television.

[0002]

2. Description of the Related Art When a lens sheet such as a Fresnel lens or a lenticular lens is manufactured, its size is relatively small, and when it is mass-produced, a synthetic resin injection molding method is generally used. Further, when manufacturing a relatively large size lens sheet for the above-mentioned screens or for condensing, a resin plate is brought into contact with a flat lens mold, and the lens surface is transferred by heating and pressurizing the resin plate to manufacture the lens sheet. Is generally taken. However, the latter method has a drawback in that it takes a long time for heating and cooling, so that productivity cannot be improved.

For this reason, recently, a method has been proposed in which an ultraviolet-curable resin liquid is interposed between the lens mold and the transparent substrate, and the resin is irradiated with ultraviolet rays to cure the resin liquid (Japanese Patent Laid-Open No. 61-17).
7215), and a transmissive screen having a Fresnel lens or a lenticular lens obtained by such a method is also known (Japanese Patent Laid-Open No. 63-167301).

[0004]

By the way, when the lens sheet as described above is used for the screen of a video projection television, in order to improve the horizontal viewing angle, the peripheral brightness, and the compactness of the television itself,
As shown in FIG. 5, the lens surface of the Fresnel lens and one surface of the double-sided lenticular lens are opposed to each other and combined, and an image is projected from the F side of FIG. 5 for use.

Further, in a video projection television, a video image can be projected from a CRT or a liquid crystal display, and the image projected on the screen can be enlarged by widening the projection angle of view. In order to widen this image, it is necessary to secure a projection distance, and the video image is magnified by using one to several reflectors inside the video projection television enclosure as shown in FIG. It is projected on the configured screen.

The mirror surface of the resin base material is used as it is for the surface of the Fresnel lens forming the screen used in this way, on which the lens is not formed.
The image projected from the projection tube (7) is reflected by A of the reflecting mirror (6) and recognized as an image on the screen (5) as shown in FIG. B) and the reflecting mirror (C) may be reflected again in that order, and appear as a ghost on the screen (D).

Further, in recent projection televisions, although the image quality and the viewing angle have been remarkably improved by improving the housing, lens shape, lens configuration, etc., the improvement of the viewing angle in the vertical direction is still insufficient.

Therefore, it is an object of the present invention to provide a lens sheet which does not generate reflected light which forms a ghost on the back surface of a screen of a video projection television and which is excellent in productivity.

[0009]

In view of the above situation, the inventor of the present invention has predicted that the back surface of the lens sheet constituting the screen is in a form in which specularly reflected light is unlikely to occur so that the occurrence of ghost can be suppressed. As a result of an examination based on the above, the present invention has been completed with good results.

That is, the gist of the present invention is that, on the other surface of the transparent substrate having an uneven shape formed on one surface,
A lens sheet is characterized in that a Fresnel lens made of an ultraviolet curable resin is formed.

The lens sheet of the present invention will be described in more detail below. The transparent substrate used in the present invention is shown in FIG.
Further, as shown in FIG. 2, an uneven shape must be formed on the surface on which the Fresnel lens is not formed.
The shape of the irregularities is not particularly limited, but for the purpose of the present invention, a shape that causes regular reflection is not preferable. By using such a lens sheet,
As shown in FIG. 3, the image reflected by B of the reflecting mirror (6) enters the screen and is recognized as an image, and the light reflected by 8 of the surface (3) having the uneven shape is not specular reflection light,
Since it becomes diffusely reflected light, generation of ghost can be prevented.

Examples of the form of the irregularities for preventing such regular reflection include a satin-finished shape, a hairline, and a kamaboko-shaped shape such as a lenticular lens. Above all, it is preferable to use a kamaboko shape such as a lenticular lens in the so-called lateral direction because the viewing angle in the vertical direction of the video projection television is widened.

The material, thickness, etc. of the transparent substrate of the present invention are not particularly limited, but those having a reduced light transmittance due to coloring, turbidity or the like are not preferred. The materials preferably used are glass and plastic, and among them, plastic sheets such as acrylic resin and polycarbonate, polyester, polycarbonate and acrylic film are more preferable. The present invention is more effective when a transparent substrate having a high reflectance, that is, a high refractive index is used.

The UV curable resin used in the present invention is also not particularly limited, but a resin having a high light transmittance is preferable because it is a lens that transmits light. From the viewpoint of ease of handling and curability, polyvalent methacrylate and / or polyvalent acrylate (hereinafter described as polyvalent (meth) acrylate), monomethacrylate and / or monoacrylate (hereinafter referred to as mono (meth) acrylate), and light It is preferably an ultraviolet curable resin composition containing an initiator as a main component.

Here, typical polyvalent (meth) acrylates include polyol poly (meth) acrylate, polyester poly (meth) acrylate, epoxy poly (meth) acrylate, and urethane poly (meth) acrylate. Are used alone or as a mixture of two or more.

As the mono (meth) acrylate, mono (meth) acrylic acid ester of monoalcohol is preferably used. The mono (meth) acrylic acid ester of the polyol is considered to be influenced by the free hydroxyl group, but when the metal type is used, the release from the metal type is deteriorated, so it is better not to use a large amount. Further, it is considered that (meth) acrylic acid and its metal salt also have a high polarity, but when a metal mold is used, release from the metal mold is deteriorated, so it is not preferable to use a large amount.

[0017]

EXAMPLES The present invention will be specifically described below with reference to examples. In this example, "Funkryl FA-321M" (Hitachi Chemical Co., Ltd., ethylene oxide-modified bisphenol A dimethacrylate) 4 was used as an ultraviolet curable resin composition.
5 wt%, "NK Ester A-BPE-4" (Shin Nakamura Chemical Co., Ltd., ethylene oxide modified bisphenol A diacrylate) 25 wt%, "Sartomer 285" (Sartomer, tetrahydrofurfuryl acrylate) 3
To the mixture of 0% by weight, as a photoinitiator, "Darocur 1
173 "(2-hydroxy-2, manufactured by Merck Japan Co., Ltd.
-Methyl-1-phenylpropan-1-one) was added to the above mixture in an amount of 3% by weight. The above ultraviolet curable resin composition was interposed between a stamper having a Fresnel lens shape and the transparent base material shown in the following examples, and an ultraviolet integrated irradiation dose of 320 to 390 nm was applied from the base material side with a high pressure mercury lamp of 80 W / cm. Is 1100 mJ
After curing by irradiating with ultraviolet rays so as to be / cm ² , the Fresnel lens sheet was obtained by peeling from the stamper.

Example 1 Hairline processing on one surface (Ra = 0.1 μ measured in a direction orthogonal to the hairline)
A 2 mm thick methacrylic resin plate “Acrylite # 000” (made by Mitsubishi Rayon Co., Ltd., containing no ultraviolet absorber) subjected to m) was used as a transparent substrate to obtain a Fresnel lens. The direction of the hairline was the same as the horizontal direction of the screen. The Fresnel lens and the lenticular lens were combined and mounted on a video projection television for observation, but no ghost, which is considered to be the influence of specular reflection on the back surface of the Fresnel lens, was observed. In addition, no change was observed in image bleeding due to the hairline. Furthermore, the screen gain in the vertical direction is 1/1 of the value measured in front of the center.
The angle of 0 was 23 °.

(Example 2) A Fresnel lens was obtained by using a 125 μm polyester film having a hairline finish similar to that of Example 1 on one surface. When the Fresnel lens and the lenticular lens were combined and mounted on a video projection television for observation, no ghost, which is considered to be the influence of specular reflection on the back surface of the Fresnel lens, was observed. In addition, no change was observed in image bleeding due to the hairline. Further, the angle at which the gain of the screen in the vertical direction was 1/10 of the value measured in front of the center was 22 °.

Example 3 A Fresnel lens was obtained by using a polycarbonate sheet having a thickness of 400 μm and having a lenticular lens (pitch: 2 mm, sectional shape: circumferential shape with a radius of 15 mm) pressed on one surface. The cylinder direction of the lenticular was set to be the same as the lateral direction of the screen. The Fresnel lens and the lenticular lens were combined and mounted on a video projection television for observation, but no ghost, which is considered to be the influence of specular reflection on the back surface of the Fresnel lens, was observed. Further, no change was observed in image bleeding and the like due to the formation of the lenticular lens. Furthermore, the screen gain in the vertical direction is 1/1 of the value measured in front of the center.
The angle of 0 was 27 °, and the viewing angle in the vertical direction was improved.

Comparative Example 1 A Fresnel lens using a methacrylic resin plate as a base material was obtained in the same manner as in Example 1 except that hairline processing was not applied. When this Fresnel lens and a lenticular lens were combined and mounted on a video projection TV and observed, a slight ghost, which is considered to be the influence of specular reflection on the back surface of the Fresnel lens, was observed. No particular bleeding of images was observed. Further, the angle at which the gain of the screen in the vertical direction was 1/10 of the value measured in front of the center was 22 °.

Comparative Example 2 A Fresnel lens using a polyester film as a base material was obtained in the same manner as in Example 2 except that hairline processing was not applied. When this Fresnel lens and a lenticular lens were combined and mounted on a video projection television and observed, a ghost that was considered to be the influence of specular reflection on the back of the Fresnel lens was observed. No particular bleeding of images was observed. Further, the angle at which the gain of the screen in the vertical direction was 1/10 of the value measured in front of the center was 21 °.

Comparative Example 3 A Fresnel lens using a polycarbonate sheet as a base material was obtained in the same manner as in Example 3 except that the lenticular lens shape was not formed by pressing.
When this Fresnel lens and a lenticular lens were combined and mounted on a video projection television and observed, a ghost that was considered to be the influence of specular reflection on the back of the Fresnel lens was observed. No particular bleeding of images was observed. Further, the angle at which the gain of the screen in the vertical direction was 1/10 of the value measured in front of the center was 22 °.

[0024]

As is apparent from the above description, in the lens sheet according to the present invention, the image is specularly reflected by the lens sheet constituting the screen, the generation of the ghost that occurs can be suppressed, and a better image can be observed. It has an extremely excellent effect. Further, by making the uneven structure of the present invention a lenticular lens-like structure, it brings about a great effect that the viewing angle in the vertical direction is also improved, which is a big problem of the current video projection television.

[0025]

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of a lens sheet of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of a lens sheet of the present invention in which a surface on which a Fresnel lens made of an ultraviolet curable resin is not formed is a lenticular lens.

FIG. 3 is a cross-sectional view of a video projection television using the lens sheet of the present invention, showing an example in which specular reflection does not occur on a screen and a ghost does not appear.

FIG. 4 is an example of a cross-sectional view of a video projection television in which an image specularly reflected at point B on the screen is reflected again at point C and appears as a ghost at point E because a conventional lens sheet is used.

FIG. 5 is an enlarged cross-sectional view of a currently used screen, which is an example in which a lenticular lens 11 and a Fresnel lens 12 are combined.

FIG. 6 is a cross-sectional view of a general video projection television.

[Explanation of symbols]

1 transparent base material having an uneven shape 2 Fresnel lens part made of an ultraviolet curable resin 3 uneven shape 4 lenticular lens shape 5 screen using a conventional lens sheet (mirror surface structure) 6 reflecting mirror 7 projection source 8 diffuse reflection light 9 specular reflection Light (ghost image) 10 Projection image 11 Double-sided lenticular lens 12 Fresnel lens 13 Screen

Claims (2)

[Claims] 1. A lens sheet, characterized in that a Fresnel lens made of an ultraviolet curable resin is formed on the other surface of a transparent base material having an uneven shape formed on one surface. 2. The lens sheet according to claim 1, wherein the uneven shape is a lenticular lens shape.