JP2890430B2 - Screen for rear projection display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a screen for a rear projection type display, and in particular, to a high resolution (hi-vision) whose demand is increasing in recent years.
The present invention relates to a rear projection display screen having a large screen for a television.

[Prior art] Conventionally, a direct-view CRT (so-called cathode ray tube) has been used as a television display. However, the image quality has been improved due to the recent development of a high-resolution (high-vision) system, which has been impractical in the past. Large screen display, which was possible, is now possible. However, if such a large screen is to be realized by a direct-view CRT, its practicality is limited due to the remarkable increase in weight and shape, high price, and increase in power consumption. There is.

As a method for solving this problem, a projection display is being developed. The display does not look directly at the screen on the CRT, but projects the image on the CRT having a relatively small shape as a light source onto a large screen, thereby enabling reduction in size and weight. At this time, two methods have been proposed in which a projection light source is arranged in front of a screen display (front projection display) or arranged behind the display (rear projection display).
Front-projection displays have the advantage of simple optical path design, but they are difficult to see in a bright room, and there is a projection device in front of the screen (audience side) to obstruct images on the screen. In this arrangement,
The disadvantages are that the whole device is not so small, and it is not practical. Conversely, rear projection displays
Although the optical path design is complicated, it is easy to see even in a bright room, the front of the screen is open, and the light source and projection optics can all be stored on the back, so the entire device is extremely small despite its large screen display. Is now being put to practical use.

In a rear projection display, since a high-quality image as a light source must be faithfully reproduced in both brightness and gradation, a screen to be used is required to have contradictory characteristics of high light-collecting property and light-scattering property. That is, the former high light-condensing property is necessary to obtain a high-luminance image, and the latter light-scattering property is necessary to enable a projected image to be viewed from a wide viewing angle. In order to satisfy this requirement, a two-sheet screen as shown in FIG. 2 in which a transparent sheet having a lenticular shape is arranged in front of the Fresnel lens, and a front surface formed of one kind of material as shown in FIG. An integrated screen having a lenticular shape and a Fresnel lens shape on the back surface has been proposed.

[Problems to be Solved by the Invention] However, in the above-described conventional technology, a stray light is large in a two-screen structure, so that a clear image cannot be obtained. Further, in the integrated screen, there is a problem that the sacrifice in characteristics is increased because the two optical elements are formed of one kind of material.

That is, in the Fresnel lens portion, generally, the smaller the Fresnel angle is, the smaller the reflection loss and the difference in the amount of transmitted light between the red, green, and blue colors are, which are advantageous for improving image quality and screen brightness, respectively. The finer the pitch of the lenticular portion, the higher the resolution. However, reducing the Fresnel angle increases the focal length of the entire Fresnel lens, which means an increase in the projection distance, that is, an increase in the optical path from the light source to the screen, resulting in an increase in the size of the entire display. Will be. In this regard, an integrated screen that uses a high-refractive-index glass as the material of the Fresnel lens and has a small Fresnel angle and a large refraction angle to shorten the projection distance has also been tried. Such a glass has poor moldability and strength, so that it is difficult to produce a lenticular shape on the front surface. Further, even if a fine lenticular shape is successfully formed, glass is liable to chip off and is not practical.

Therefore, a rear projection display screen having satisfactory performance has not been obtained at present.

[Means for Solving the Problems] As described above, in the related art, a screen for a rear projection display having high luminance, high resolution, wide viewing angle, and sufficient durability for practical use is manufactured. It was impossible to produce in large quantities and at low cost. The present invention has been made to solve such a deficiency of the prior art.

That is, the present invention has a back surface of a plastic sheet made of acrylic resin, polycarbonate resin, urethane resin or polyolefin resin and having one surface having a lenticular shape, a high refractive index glass having a refractive index of 1.55 or more, and one surface having a Fresnel lens shape. The back surface of the glass plate is joined and integrated, and a plastic sheet on the front side,
It is an object of the present invention to provide a screen for back-side administration type display, wherein a glass plate is arranged on the back side.

Fig. 1 shows a rear projection display screen according to the present invention. The front has a lenticular shape, the rear has a Fresnel lens shape, the front has a plastic sheet, the rear has a glass plate, and the plastic sheet has Of the glass plate and the back surface of the glass plate with respect to the Fresnel lens-shaped surface. Therefore, only the shape is similar to the conventional integrated screen, but it is completely different in that it is configured as described above. In particular, a plastic having excellent moldability is used for the front surface where a complicated shape and durability are required, and glass is used for the back surface where a high refractive index is required. Thus, what can best demonstrate the characteristics of the present invention is that the glass on the back surface is made of high refractive index glass,
Use 1.55 or more glass. As a result, the focal length can be shortened, and the size can be reduced. As the material of such a glass, those described in Sakuka, Sakaino, Takahashi, "Glass Handbook" (Asakura Shoten), p.71-p.84, can be applied. In addition, it is important that the plastic material of the plastic sheet used for the front part has adhesiveness, transparency, and abrasion resistance to glass. For example, acrylic resin, polycarbonate resin, urethane resin, and polyolefin resin are used as suitable plastics. .

A conventionally known method can be employed for manufacturing the rear projection display screen of the present invention. A plastic sheet having a lenticular shape on one side can be obtained, for example, by making a mold corresponding to a desired lenticular shape and using the mold as a press mold to transfer the lenticular shape to one side of the plastic sheet. The plastic sheet and the glass plate are joined together by bonding the back of the lenticular-shaped surface of this plastic sheet and the back of the Fresnel-lens-shaped surface of a glass plate having a Fresnel lens shape to the rear surface of the glass sheet. There is a way to get a screen. Further, as another example, the lenticular mold is arranged on one side, and the lenticular-shaped surface is arranged alongside the glass plate having the Fresnel lens-shaped surface so as to face the rear surface to the Fresnel lens-shaped surface. A cavity is formed by winding an adhesive tape around the side surface, and a polymerizable monomer that can be molded into a plastic sheet is injected into the cavity, and then the monomer is polymerized and cured by heat or light, so that the plastic sheet and glass are substantially removed. There is also a method of obtaining a screen for a rear projection display in which the screen is joined and integrated.

[Example] Using glass (SF15) having a refractive index of 1.70 as a material, the pitch was
A glass plate of 40 inches in size and 2 mm in thickness with a 0.35 mm Fresnel lens shape formed on one side, a polyurethane sheet with a 0.5 mm pitch lenticular shape on the back and a 0.5 mm pitch lenticular shape on the whole surface of this glass plate The rear surface of the lenticular surface was joined by thermocompression bonding and integrated to produce a rear projection display screen.

The projection distance of the obtained screen was 1.13 m.

[Comparative Example] Using an acrylic resin having a refractive index of 1.49 as a material, an integrated 40-inch screen whose rear surface is a Fresnel lens with a pitch of 0.35 mm and whose front surface is a lenticular lens with a 0.5 mm pitch is used. Made.

 The projection distance of this screen was 1.62 m.

[Effects of the Invention] The rear projection display screen of the present invention facilitates molding of a complicated shape by using plastic for the front lenticular lens portion for expanding the field of view of the image, and has a high refractive index glass on the rear surface. The use of a Fresnel lens made of a product has the effect that the size of the display can be reduced.

In particular, since plastic and glass are joined and integrated to reduce stray light and achieve weight reduction while maintaining the rigidity of the entire screen, such as high vision, which is expected to spread in the future, at least
This is effective for devices that require a large screen of 50 inches.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rear projection display screen of the present invention, FIG. 2 is a cross-sectional view of a conventional two-screen screen, and FIG. 3 is a cross-sectional view of a conventional integrated screen. Numerals 1, 2 denote spherical and trapezoidal lenticular lens-shaped surfaces, 3 denotes a Fresnel lens-shaped surface, 4 denotes plastic, and 5 denotes glass.

Claims (3)

(57) [Claims] 1. A back surface of a plastic sheet made of an acrylic resin, a polycarbonate resin, a urethane resin or a polyolefin resin and having a lenticular shape on one surface, a high refractive index glass having a refractive index of 1.55 or more, and a Fresnel lens shape on one surface. A rear administration type display screen, wherein a rear surface of a glass plate is joined and integrated, and a plastic sheet is disposed on a front side and a glass plate is disposed on a rear side. 2. The rear projection display screen according to claim 1, wherein a high-vision image is projected. 3. The screen for a rear projection type display according to claim 1, wherein the screen is 40 inches or more in size.