JPS63139331A - Rear projection screen - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a rear projection screen used in a video glogeation television or the like. (Prior Art) In principle, a rear projection device such as a video projection television, as shown in FIG. Screen (projected from the back side of SJ, this screen field)
I'm supposed to look at the other side. However, increasing the distance from the CRT to the screen (S) in this way increases the size of the projection device, so in reality, the distance from the CRT to the screen (S) increases. (As shown in C1, a method is used in which one to three mirrors (2) are combined to reflect the image once and then project the image. However, in the method shown in FIG. 1A, the height of the device increases; In addition, (BJ, (C)) also had some aspects that could not be said to be miniaturized in terms of height and depth. Also, the screen used in such a projection device,
Many devices have a circular Fresnel lens on the incident side, which brightens every corner of the screen, but this circular Fresnel lens is
As shown in FIG. 3, since the lens surface is continuous through the non-lens surface (mouth), there is a problem in that the incidence on the non-lens surface (mouth) shown by diagonal lines has a negative effect on resolution. The applicant has developed a screen for observing an image by entering it from the rear side at a steep angle, and is provided with a large number of prism groups parallel to the incident plane, and each prism constituting the prism group is We proposed a screen that can rapidly reduce the depth of the device by providing a total reflection surface so that the incident light is totally reflected on the total reflection surface and emitted to the observation side (Japanese Patent Application No. 59-29964). However, in conjunction with such a screen, there has been a problem that the contrast may be reduced depending on the position of the reflecting mirror. (Problems to be Solved by the Invention) The present invention has been developed in view of the above points, By projecting the light emitted from the screen at a steep angle, the dimensions in the depth and height directions can be reduced, thereby reducing the size of the projection device, and providing a uniform and bright rear projection screen without reducing the contrast. (Means for solving the problem) The present invention has been made to achieve the above object,
The gist of this is that it is a screen on which images are observed by entering the light from the back side at a steep angle, and it consists of a first screen base material located on the light source side and a second screen base material located on the peep festival side. A large number of prism groups are provided parallel to the incident surface of the first screen base material, and each prism constituting the prism group is provided with a total reflection surface, so that the incident light is reflected from the total reflection surface. The second screen base material is totally reflected and emitted to the observation side, and vertical lenticular V lenses are provided on at least one surface of the second screen base material.
Moreover, a film having a striped base plate portion corresponding to a portion of the first screen base material from which no light is emitted is applied to the exit surface of the first screen base material or the entrance surface of the second screen base material. It is located on a rear projection screen that features a touch screen. The present invention will be described below with reference to drawings of embodiments. FIG. 4 is a schematic diagram for explaining the basic configuration of the rear projection screen of the present invention, in which (no is a CRT, (- is a lens system, (S) is a rear projection screen, and the CRT (P
) is incident on the back of the rear projection screen (S) at a steep angle. Here, the angle (θ) when incident on the rear projection screen (S) is approximately 40 to 85
°. At this time, the distance 11i1i (4) from the CRT (P) to the rear projection screen (S) is the same as in the conventional method, but since the C!RT (P) is located diagonally downward, the distance in the depth direction (t ') is L' = A cos
θ and υt can be made extremely small. However, this does not necessarily mean that the height is small, so in reality one mirror (Ml) is used as shown in Figure 5.
It is desirable to reduce the height and the length in the depth direction by using . By the way, in the rear projection screen (B) of the present invention, light is incident from the rear side at a steep angle.

FIG. 6 shows [81]. This first screen base material (day 1) is provided with a large number of prism groups parallel to the incident plane, and each prism (1) constituting the prism group is provided with a total reflection surface (1A). The incident light is totally reflected by the total reflection surface (1A) and emitted to the observation side. In the figure (1B) is a total reflection surface (1A
). Note that the first screen base material (
As shown in the figure, the prism (1) provided on the light source side of 1) has both the incident facing surface (1B) and the total reflection surface (1A) that are linear, but one or both of them are convex outward. It may be curved. A second screen base material is placed and used on the observation side of the first screen base material (al), and by using such a first screen base material (81), the upper The following problems arise when a mirror is placed in a mirror. That is, as shown in Fig. 7, the external light incident at a relatively small angle C1f') is totally reflected on the total reflection surface A) of the first screen base material (S+), and is emitted from the opposite side (1B). Mirror (M
After reaching the prism (1), it is reflected and returns to the prism (1), where it is totally reflected and emitted to the observation side as shown in the figure. For this reason, the image on the viewing side becomes whitish and the contrast decreases. Therefore, in the present invention, the first screen printing (S
Focusing on the fact that 1) has a part that does not emit the original light due to its structure, we intend to use it in conjunction with a film (2J tl'') that has striped light absorbing parts (2A) corresponding to this. In other words, Fig. 8 As shown in FIG.
) is brought into contact with the exit surface of the first screen base material (81), or as shown in FIG. 9, the second screen base material (S
This is achieved by bringing the light into contact with the incident surface of [2]. In addition, such a film (2) can be prepared by forming the light-absorbing portion (2A) on a translucent film by a printing method such as screen printing, gravure printing, or offset printing, or by the Grotztinog method, or by forming a so-called photosensitive film. The light absorbing portion (2A) may be formed by photographic processing using a film. In addition, the method of contacting this film (2) to the screen base material is to apply an adhesive to part or all of it and adhere it, or in the case of a rigid film, to attach it only at the periphery, or to attach it to the screen base material. The second screen base material (Sl) of the present invention may be provided with a vertical lenticular lens (3) on at least one surface, or may be provided with a vertical lenticular lens (3) on at least one surface. ) has the function of spreading light in the horizontal direction, so it is possible to widen the horizontal viewing range. A lenticular lens (3) is provided, or in the case of FIG. ) When a lenticular lens is provided on the viewing side of the lenticular lens, the horizontal field of view can be further expanded by providing a total reflection surface in each lens unit that makes up this lenticular lens. Regarding the structure and function of the lens surface, see Japanese Patent Application No. 56-51194, Japanese Patent Application No. 1987-90544, Japanese Patent Application No. 56-91896, all filed by the same applicant.
Patent application No. 56-212584, Patent application No. 56-29178
As detailed in Japanese Patent Application No. 57-59589,
The explanation here will be omitted. In addition, in a lenticular lens having such a total reflection surface, the total reflection surface becomes a part that does not transmit light, so it is possible to provide an external light absorption layer on this part directly or through a thin layer that becomes a light reflection layer. can. In addition, in the present invention, in order to improve the uniformity of brightness as a screen, for example, the light source 911 of the second screen base material (Sl) in FIG. 8, the light source 911 of the first screen base material (S+) in FIG. A circular Fresnel lens can also be provided on the sensor side. In the above example, for the light source side of the screen,
Although the light is incident diagonally from above, it is also possible to make it incident diagonally from below, or in some cases, the prism group may be converted by 90 degrees instead of being arranged in series so as to extend horizontally. It may also be configured to extend vertically. Since the rear projection screen of the present invention projects an image from diagonally backward, the image on the screen is distorted and blurred, but these can be solved by the following measures of the projection system. Solvable. That is, image distortion can be corrected by assuming the amount of distortion in each part and using the electric circuit of the CRT. Also, the blurring of the image is caused by the difference in distance from the lens system to the screen, so l:! The image entering the lens system from RT may be made to have a constant angle with respect to the optical axis so that the image has the same focal length on the screen. Acrylic resin is the most suitable material for the rear projection screen of the present invention, since acrylic resin is particularly excellent in terms of optical properties and moldability. However, instead of this, vinyl chloride resin,
It is also possible to use polycarbonate resin, oleene thread resin, styrene resin, etc. When using these synthetic resin materials, the rear projection screen according to the present invention can be manufactured by extrusion molding, hot press, or injection molding. I can do it. A light diffusing means may be provided on the base material or separate sheet constituting the folded rear projection screen of the present invention to further improve light diffusing properties. As this light diffusing means, a synthetic resin constituting the base material, for example, an acrylic resin, is used with 5i02.0aCO3°At203
, TiO3, BaSO4, ZnO, AL(0H)s
, fine glass powder, organic diffusing agent, etc. are mixed and distributed uniformly in the medium with one type of diffusing substance or an additive of 2 m or more that does not melt or chemically change, or these diffusing substances are mixed and distributed in the medium. It is preferable to form a layer containing It is also effective to form a fine matte surface on the projection side and/or the observation side. If such a means for imparting light diffusivity is taken, the diffusivity of the screen in the horizontal and vertical directions is compensated for and uniformity can be improved. (Effects of the Invention) The present invention has the configuration as described in detail above, and the light incident at the rear of the screen at a steep angle can be efficiently emitted to the observation surface by the action of total reflection. When employing the rear projection screen according to the invention, the relative position of the glosiector serving as the light source is positioned diagonally to the rear, thereby making it possible to downsize the entire projection device and providing a rear projection screen that does not reduce contrast. There are advantages.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of the optical path from a projector to a conventional rear projection screen, Figure 5 is a partial side view of a Funnel lens used in a conventional rear projection screen, and Figures 4 and 5 are illustrations of the light path from a projector to a conventional rear projection screen. An explanatory diagram of the optical path from the glow projector when the rear projection screen of the invention is used, FIG. 6 is a sectional view showing a part of the first screen base material used in the rear projection screen of the invention, and FIG. 8 and 9 are partial sectional views showing an embodiment of the present invention. (S)...Screen (Sl)...First screen base material (S2)...
...Second screen base material (υ) ... Prism (1 person) ... Total reflection surface (2) ... Film (2 people) ...・Light absorption part <3)...Lenticular lens patent applicant Mitsubishi Rayon Co., Ltd. Tame17 412 Jiri (8)<A) Tail 40

Claims (1)

[Claims] 1. A screen for observing an image by allowing light to enter from the back side at a steep angle, the first screen base material being located on the light source side and the second screen being located on the viewing side. A large number of prism groups are provided parallel to the incident surface of the first screen substrate, and each prism constituting the prism group is provided with a total reflection surface so that the incident light is totally reflected. A vertical lenticular lens is provided on at least one surface of the second screen base material, and a portion of the first screen base material from which light is not emitted. A rear projection screen characterized in that a film having striped light absorbing portions corresponding to the above is brought into contact with the exit surface of the first screen substrate or the entrance surface of the second screen substrate. 2. Claim 1, characterized in that a vertical lenticular lens is provided on the observation side of the second screen.
Rear projection screen as described in section. 3. The rear projection screen according to claim 2, wherein a total reflection surface is provided on the lens element constituting the lenticular lens. 4. The rear projection screen according to claim 2 or 3, characterized in that an external light absorbing layer is provided in the light-opaque portion of the lenticular lens. 5. A rear projection screen according to claim 1, 2, 3, or 4, characterized in that a base material constituting the screen is provided with a light diffusing means.