JPH07230127A - Projection screen - Google Patents

Abstract

PURPOSE:To reduce a white band in a horizontal direction generated due to the stray light of a screen by providing a mat forming processing plane which scatters internal reflected light at a vertical convergence linear Fresnel lens sheet. CONSTITUTION:Light projected from a projector is made incident and refracted on the vertical convergence linear Fresnel lens sheet 14 from the smoothing plane of the vertical convergence linear Fresnel lens sheet 14 via a horizontal convergence linear Fresnel lens sheet 12, and it is emitted from a Fresnel lens part 14B, however, a part of it is reflected on the interface of a lens and the air, then, it goes to return light to the lens sheet. Since such stray light is scattered on the mat forming processing plane 18 when it is reflected again on the incident plane of a base film 14A, a position where it is emitted from the Fresnel lens part 14B to the outside can be expanded, and no local emission of the stray light is prevented from occurring, which makes the light hard to be observed. Therefore, the white band extending in the horizontal direction by the stray light due to the vertical convergence linear Fresnel lens sheet can be eliminated or weakened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection screen for a rear projection type television, and more particularly, the screen sheet includes a vertical condenser linear Fresnel lens sheet, a horizontal condenser linear Fresnel lens sheet, and a lenticular lens sheet. A projection screen composed of.

[0002]

2. Description of the Related Art A projection screen for a rear projection type television is composed of a Fresnel lens part for converging the projection light to the observation side and a lenticular lens part for scattering the projection light to form an image. There are a single screen type formed on the sheet of No. 1 and a double screen type formed on two sheets, and the latter is often used in the case of consumer television.

In any of the projection screens described above, Fresnel lenses are formed in concentric circles, and a die for manufacturing the concentric Fresnel lens sheet is cut into a rotary disk. is there.

The circular Fresnel lens uses a flat plate-shaped mold, which is a mold cut on the rotating disk. The "press method" of pressing a transparent resin flat plate onto a heated mold or thermal polymerization in a mold cell. "Casting method" or applying a UV curable resin on a mold, laminating a transparent resin flat plate, and exposing to ultraviolet rays to give a lens shape made of the UV curable resin on the transparent resin flat plate "U
It was manufactured by the "V method" or the like.

However, in either method,
Since the Fresnel lens is concentrically formed,
Inevitably, it is necessary to produce each sheet individually, so that the productivity is poor and it is difficult to reduce the production cost as compared with the lenticular lens sheet that can be continuously produced by the extrusion method.

On the other hand, as disclosed in Japanese Utility Model Publication No. 56-74429 and Japanese Utility Model Publication No. 56-74430, a Fresnel lens is used in one direction as an alternative to the concentric circular Fresnel lens. It has been proposed to use two formed linear Fresnel lenses so that their lines are orthogonal to each other. These are molding methods capable of continuous production, such as an "extrusion method" and a method of curing a UV resin on a resin film.

[0007]

Generally, in a projection screen, part of the projected light is reflected by the lens surface and becomes stray light that travels in the sheet. This stray light caused image interference such as double structure and rainbow.

In particular, in the case of the optical system using the linear Fresnel lens as described above, stray light becomes a white band extending in the horizontal direction and is observed more strongly than the circular Fresnel rainbow, which is not preferable for image observation. There is.

The present invention has been made in view of the above problems of the prior art. Even when the linear Fresnel lens sheets are arranged in the horizontal direction and the vertical direction, the horizontal line caused by stray light on the screen is generated. It is an object of the present invention to provide a projection screen with reduced white band in the direction.

[0010]

According to the present invention, at least three sheets of a horizontal light collecting linear Fresnel lens sheet, a vertical light collecting linear Fresnel lens sheet, and a light diffusing lenticular lens sheet are arranged from the light source side. In the projection screen constituted by the above, the above object is achieved by the projection screen characterized in that the vertical converging linear Fresnel lens sheet is provided with a light diffusing means.

Further, in the present invention, the vertical condensing linear Fresnel lens sheet may be a sheet in which a lens is formed on the base film by an ultraviolet curable resin.

Further, in the present invention, the light diffusing means may be a matting surface provided on the light incident surface of the base film.

In the second aspect, the light diffusing means may be a matte-treated surface provided at the interface between the base film and the ultraviolet curable resin.

Further, in claim 2, the light diffusing means may be one in which a light diffusing agent is contained in the base film.

In the second aspect, the light diffusing means may be a light diffusing film laminated on the base film.

Further, in claim 2, the light diffusing means may be a light diffusing layer coated on the surface of the base film.

In the present invention, the light diffusing means may have a matte treatment surface applied to a light incident surface of the base film and a matte treatment applied to an interface between the base film and the ultraviolet curable resin. Two or more of a surface, a film containing the light diffusing agent as the base film, a light diffusing film laminated on the base film, and a light diffusing layer coated on the surface of the base film. You may comprise combining.

[0018]

The light projected from the projector enters the Fresnel lens from the smooth surface side, is refracted and exits from the lens forming side, but part of it is reflected at the interface between the lens and the air and returns to the lens sheet to become stray light. . Most of this stray light is emitted to the observation side after being reflected once or several times in the lens sheet, but it is generally observed as a rainbow in the case of a circular Fresnel lens, and as a white band in the case of a linear Fresnel lens. To be observed.

When the horizontal light collecting linear Fresnel lens sheet and the vertical light collecting linear Fresnel lens sheet as described above are used in combination, the white band has a light diffusion characteristic of the projection screen which is generally wide in the horizontal direction and vertical. Since it is set narrow in the direction, the white band extending in the vertical direction due to the horizontal light collecting linear Fresnel is not observed, and only the white band extending in the horizontal direction resulting from the vertical light collecting linear Fresnel is strongly observed.

According to the present invention, the linear Fresnel lens sheet for converging the projected light in the vertical direction is provided with the light diffusing means to efficiently remove the white band extending in the horizontal direction due to the vertically converging linear Fresnel. Is.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, as shown in FIG. 1, a projection screen 10 for a rear projection type television is used.
From the light projection side, a horizontal light collecting linear Fresnel lens sheet 12, a vertical light collecting linear Fresnel lens sheet 14, and a lenticular lens sheet 16 for light diffusion are arranged in this order to form an HVL type. The incident surface side of the Fresnel lens sheet 14 is a matte (matte) treated surface 18.

Horizontally focused linear Fresnel lens sheet 12
Forms a Fresnel lens portion 12B made of a cured product of a urethane acrylate-based UV curable resin on a polyester base film 12A, and the vertical light collecting linear Fresnel lens sheet 14 is a polyester base film 14
Each of them is formed by forming a Fresnel lens portion 14B made of a cured product of a urethane acrylate-based ultraviolet curable resin on A.

Further, the lenticular lens sheet 16
Is formed by forming a light emitting surface 16A on which light shielding layer forming convex portions are alternately arranged on the light emitting side, and further forming a light shielding layer 16B of black ink on the light shielding layer forming convex portions. There is.

Horizontally focused linear Fresnel lens sheet 1
2. Since the vertical converging linear Fresnel lens sheet 14 and the lenticular lens sheet 16 are all flexible film lens sheets, even if these three sheets are combined to form a projection screen, they have mechanical strength to stand on their own. Absent. Therefore, by combining transparent resin plates and fixing them together in a frame (both not shown),
The lens sheet is reinforced to provide structural strength such as independence and strength against surface friction.

The matting surface 18 formed on the incident surface of the vertical light-converging linear Fresnel lens sheet 14 diffuses light. The surface is roughened or coated with a light diffusing ink or paint. It is formed.

Next, the operation of this embodiment will be described with reference to FIG.

The light projected from the projector passes through the horizontal light-collecting linear Fresnel lens sheet 12, enters the vertical light-collecting linear Fresnel lens sheet 14 from the smooth surface of the vertical light-collecting linear Fresnel lens sheet 14, and is refracted. Although it is emitted from the Fresnel lens portion 14B, a part thereof is reflected by the interface 14C between the lens and the air and returns to the lens sheet to become stray light.

This stray light is scattered by the matting surface 18 when it is reflected again on the incident surface of the base film 14A, so that the position where it is emitted from the Fresnel lens portion 14B is widened and locally strong. Stray light is not emitted and it becomes difficult to observe.

Therefore, the white band extending in the horizontal direction due to the stray light caused by the vertical focusing linear Fresnel lens is removed or weakened.

Next, a second embodiment of the present invention shown in FIG. 3 will be described.

In the second embodiment, the interface between the base film 14A of the vertical light converging linear Fresnel lens sheet 14 and the Fresnel lens portion 14B is used as the matt surface 20. The matting treatment is applied to the base film 14A before the Fresnel lens portion 14B is UV-cured and molded.

Also in this embodiment, since the internally reflected light is scattered on the matt processing surface 20 on the incident side of the Fresnel lens portion 14B, it is difficult to observe a white band in the emitted light as in the first embodiment. .

As described above, the matting treatment surfaces 18 and 20 are for roughening the surface or coating light diffusing ink or paint. In the present invention, the matting treatment means internal reflection light. Need only scatter when it is reflected on the incident side. For example, as in the third embodiment of the present invention shown in FIG. You may use the base film 14D which mixed.

Further, as in the fourth embodiment of the present invention shown in FIG. 5, a light diffusing film 22 is laminated on the light incident surface side of the base film 14A of the vertical converging linear Fresnel lens sheet 14. Good.

Further, as in the fifth embodiment of the present invention shown in FIG. 6, the light diffusion layer 2 is formed on the light incident surface side of the base film 14A.
4 may be applied.

Further, two or more of the matting processing means may be combined to scatter the internally reflected light.

Here, when the light diffusing film 22 is laminated on the base film 14A, and when the light diffusing layer 24 is used.
In any of the cases where is applied to the base film 14A, it is desirable that the refractive index thereof is lower than that of the base film 14A.

Further, as described above, since the vertical light-converging linear Fresnel lens sheet 14 is provided with the light diffusion layer, the projection light is doubly diffused by the vertical light-converging linear Fresnel lens sheet 14 and the lenticular lens sheet 16. However, if the lenticular lens sheet 16 and the light condensing layer of the vertical condensing linear Fresnel lens sheet 14 are largely separated from each other, the resolution is lowered, and therefore the vertical condensing linear Fresnel lens sheet 14 is the same as that of the embodiment of the present invention. As described above, it is preferable to form a film, and it is better not to form a plate.

Further, since the vertical condensing linear Fresnel lens sheet 14 causes diffusion, if the obtained image is whitish and the contrast is lowered depending on the ultraviolet curable resin, the material of the base film, the degree of diffusion, the method, and the like. , The light diffusion capability of the lenticular lens sheet 16 is reduced by the amount of light diffused by the linear Fresnel lens sheet, or the vertical converging linear Fresnel lens sheet 1
It is also effective to color the 4 or lenticular lens sheet 16.

When the horizontal and vertical linear Fresnel lens sheets are used in combination, generally, moire fringes may occur between the horizontal condenser linear Fresnel lens sheet and the lenticular lens sheet. Moire fringes can be reduced by providing the vertically converging linear Fresnel lens sheet 14 with a diffusion function as in the present invention. Also, in both the horizontal converging linear Fresnel and the vertical converging linear Fresnel, there is a possibility that a line may be formed in the image at the center portion of the lens sheet depending on the cutting method and the cutting accuracy of the mold that is the mother die. Further, by providing a diffusion layer for scattering the internally reflected light on the vertically converging linear Fresnel lens sheet 14, it is possible to make the line in the central portion less visible.

[0042]

Since the present invention is configured as described above, in a projection screen using linear Fresnel lenses that are orthogonal to each other in the horizontal and vertical directions, it is caused by stray light due to internally reflected light generated at the interface between the lens and air. It is possible to reduce the white band in the displayed image.

[Brief description of drawings]

FIG. 1 is a perspective view with a partial cross-section showing a main part of an embodiment of a projection screen according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part showing the relationship between incident light, emitted light and internally reflected light in the same example.

FIG. 3 is a sectional view similar to FIG. 2, showing the essential parts of a second embodiment of the present invention.

FIG. 4 is a sectional view similar to FIG. 2, showing the essential parts of a third embodiment of the present invention.

FIG. 5 is a sectional view similar to FIG. 2, showing an essential part of a fourth embodiment of the present invention.

FIG. 6 is a sectional view similar to FIG. 2, showing the essential parts of a fifth embodiment of the present invention.

[Explanation of symbols]

 10 ... Projection screen 12 ... Horizontal condensing linear Fresnel lens sheet 12A, 14A, 14C, 14D ... Base film 12B, 12B ... Fresnel lens part 14 ... Vertical condensing linear Fresnel lens sheet 16 ... Lenticular lens sheet 18, 20 ... Matting Treatment surface 22 ... Light diffusion film 24 ... Light diffusion layer

Claims (8)

[Claims] 1. A projection screen comprising at least three sheets of a horizontal condenser linear Fresnel lens sheet, a vertical condenser linear Fresnel lens sheet, and a light diffusing lenticular lens sheet arranged from the light source side. A projection screen characterized in that a light diffusing means is provided on the vertical focusing linear Fresnel lens sheet. 2. The projection screen according to claim 1, wherein the vertical condensing linear Fresnel lens sheet is a sheet in which a lens is formed of an ultraviolet curable resin on a base film. 3. The projection screen according to claim 2, wherein the light diffusing means is a matte treatment surface provided on the light incident surface of the base film. 4. The projection screen according to claim 2, wherein the light diffusing means is a matte treatment surface provided on an interface between the base film and the ultraviolet curable resin. 5. The projection screen according to claim 2, wherein the light diffusing means is a light diffusing agent contained in the base film. 6. The projection screen according to claim 2, wherein the light diffusing means is a light diffusing film laminated on the base film. 7. The projection screen according to claim 2, wherein the light diffusing means is a light diffusing layer coated on the surface of the base film. 8. The matting treatment applied to the light-incidence surface of the base film and the matting treatment surface applied to the interface between the base film and the ultraviolet curable resin. Two or more of a surface, a film containing the light diffusing agent as the base film, a light diffusing film laminated on the base film, and a light diffusing layer coated on the surface of the base film. A projection screen characterized by being constructed in combination.