JP2873573B2 - Screen plate for projection television - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a screen plate for a projection television.

[0002]

2. Description of the Related Art Conventionally, a projection television has a configuration shown in FIG. That is, the image projected from the image projection tube 1 is reflected by the mirror 2 and forms an image on the screen plate 3. The screen plate 3 includes a Fresnel lens 4, a diffusion plate 5, and a protection plate 6, as shown in FIG. As shown in FIGS. 2 (b) and 2 (c), the diffusion plate 5 has a configuration in which a large number of mountain-shaped ridges 7 extending in the vertical direction are formed in parallel on both surfaces. The protection plate 6 is formed of a transparent plastic plate. The chevron ridges 7 of the diffusion plate 5 have a lens effect in addition to the diffusion function, and have a function of expanding a projected image in the horizontal direction. The protection plate 6 is for protecting the diffusion surface of the diffusion plate 5 from scratches and dust. However, since the protection plate 6 is a transparent plate having a smooth surface, the surrounding lighting equipment is projected and the image is difficult to see. I do.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the necessity of using a protection plate outside a diffusion plate in a screen plate for a projection television.

[0004]

Means for Solving the Problems In order to solve the above problems, a screen plate for a projection television according to the present invention comprises a Fresnel lens and a diffusion plate having a large number of quadrangular pyramid-shaped protrusions over substantially the entire surface on one side. The structure is such that the lens surface of the Fresnel lens and the surface of the diffusion plate having the projections face each other and are coupled to each other. According to this configuration of the present invention, since the surface of the diffusion plate having the projection is arranged toward the Fresnel lens, it is not necessary to protect the projection surface from dust and scratches. In addition, the surface opposite to the surface of the diffusion plate having the pyramid-shaped projections, that is, the surface exposed to the front side is a matte mat surface, which solves the problem that an image becomes hard to see due to reflection of ambient light. it can.

[0005] The Fresnel lens and the diffusion plate in the projection television screen plate of the present invention can be manufactured by molding a plastic material.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. 3 (a) and 3 (b), quadrangular pyramid-shaped projections 5a are formed on the entire surface of the diffusion plate 5 in a matrix. FIG.
(a) As shown in (b), the quadrangular pyramid-shaped projections 5b can be arranged diagonally. These diffusion plates 5 include projections 5a,
The surface opposite to the surface having 5b is a matte surface. FIG.
Shows an example of the screen plate of the present invention, and the diffusion plate 5
Is disposed with the surface having the protrusion 5a facing the lens surface of the Fresnel lens 4 and is fixed to the Fresnel lens 4 by bonding or the like. The same applies to the diffusion plate 5 having the protrusion 5b. The arrow indicates the visual direction. FIG. 6 shows a method of manufacturing the diffusion plate 5 used for the screen plate of the present invention by molding a plastic material. The mold used for manufacturing includes an upper mold 6 having a concave portion 6a and a lower mold 7 having a convex portion 7a. A gate 8 for injecting a plastic material is formed on the upper die 6 outside the molding region of the diffusion plate. In manufacturing such that the concave portion 6a of the upper die 6 and the convex portion 7a of the lower die 7 are formed so that the surplus region 9 is formed outside the molding region of the diffusion plate, as shown in FIG. Type 6
The molds 6 and 7 are held in a state where a slight gap A is formed between the mold 6 and the lower mold 7, and a molten plastic material is injected from the gate 8. As a material, methyl methacrylate, polycarbonate, polystyrene and the like can be used.

When a predetermined amount of the molten plastic material is injected into the molding cavity 10, the injection is stopped, and the lower mold 7 is moved upward to reach the state shown in FIG. By this operation, the molding cavity 10 is moved by a distance indicated by B in FIG.
Is reduced, and the plastic material in the cavity 10 is compressed and molded. In this process, the excess plastic material in the molding cavity is removed from the surrounding excess area 9.
Extruded. By this method, both the quadrangular pyramid-shaped projections 5a and 5b of the diffusion plate and the matte surface on the opposite side can be simultaneously molded. When the diffusion plate of the present invention is used, there is no need to provide a protection plate outside the screen plate, and the structure is simplified. Further, by making the surface of the diffusion plate opposite to the surface having projections a matte surface, it is possible to solve the problem that an image becomes hard to see due to reflection of ambient light.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a conventional general projection television.

2A and 2B show a configuration of a screen plate of a conventional projection television, in which FIG.
Is a plan view of a part thereof, and (c) is a cross-sectional view thereof.

3A and 3B show an example of a diffusion plate used for the screen plate of the present invention, wherein FIG. 3A is a partially enlarged plan view, and FIG. 3B is a perspective view.

FIG. 4 shows another embodiment of the diffusion plate used for the screen plate of the present invention, wherein (a) is a partially enlarged plan view,
(b) is a perspective view.

FIG. 5 is a sectional view of an embodiment of the screen plate of the present invention.

FIGS. 6A and 6B show steps of manufacturing a diffusion plate used for the screen plate of the present invention, wherein FIG. 6A shows a first step and FIG.
Each step will be described.

[Description of sign]

3 ・ ・ ・ Screen plate, 4 ・ ・ ・ Fresnel lens, 5 ・
..Diffusion plates, 5a, 5b ... 4 pyramidal projections, 6 ...
Upper mold, 7 ... Lower mold,

Claims (3)

(57) [Claims] 1. A fresnel lens and a diffusion plate having a large number of quadrangular pyramid-shaped protrusions on one entire surface, wherein a lens surface of the Fresnel lens and a surface of the diffusion plate having the protrusion are opposed to each other. A screen plate for a projection television, wherein the screen plate is combined. 2. The screen plate for a projection television according to claim 1, wherein the Fresnel lens and the diffusion plate are made of a plastic material. 3. The projection television screen plate according to claim 1, wherein the surface of the diffusion plate opposite to the surface having the projections is a matte surface. Screen plate for projection television.