JPH06250290A - Screen for rear projector - Google Patents

Abstract

PURPOSE:To lessen brightness shading and to display a high-quality image even if the light of the image is made incident diagonally on a lenticular lens screen. CONSTITUTION:The central axes of lenses 15a, 15b on the incident side and exit side of the light 12 align to each other in the central part of the lenticular lens screen 15 but the central axes of lenses 15a, 15b are displaced from each other in the parts exclusive of the central part. Even the diagonal incident light 12 on the lenticular lens screen 15 is, therefore, bent in its optical axis, is made incident on the lens 15b and is emitted normally from the lens 15b without being shielded by a black stripe 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen used for a rear projector that projects an image on the back surface of the screen and transmits the image forward.

[0002]

2. Description of the Related Art A projector magnifies an image displayed on a cathode ray tube, a liquid crystal display or the like with a lens,
When projecting and having a mirror, the optical path is bent to form an image on the screen, and it is divided into two types, a front type (reflection type) and a rear type (transmission type), depending on the type of screen. .

FIG. 2 shows a conventional example of the rear projector and the screen used therein. In this rear projector, the light 12 of the image displayed on the cathode ray tube 11 is projected by the projection lens 13, and the image is formed on the screen including the Fresnel lens screen 14 and the lenticular lens screen 15. . In FIG. 2, the cathode ray tube 11 is omitted from one, and the mirror is also omitted.

The Fresnel lens screen 14 is for causing the light 12 projected by the projection lens 13 to vertically enter the lenticular lens screen 15. The lenticular lens screen 15 includes cylindrical lenses 15a, 1 on the incident side and the emitting side of the light 12, respectively.
5b are provided so that their central axes coincide with each other, and are for spreading the light 12 emitted from the lens 15b in the horizontal direction rather than the vertical direction. A black stripe 16 that is a striped black surface is provided between the lenses 15b in order to absorb external light and enhance the contrast of the image.

[0005]

By the way, the light 1 is transmitted by the Fresnel lens screen 14 as at the point x in FIG. 2, which is the central portion of the lenticular lens screen 15.
If the light beam 2 is vertically incident on the lenticular lens screen 15, this light 12 is reflected by the lens 15 as shown in FIG.
It is incident on b and normally exits from the lens 15b.

However, if a projection lens 13 having a short focal point or an oblique projection type optical system (not shown) is used for downsizing the rear projector, the Fresnel lens screen 14 is used.
The incident angle of the light 12 with respect to is large. As a result, y at the end of the lenticular lens screen 15 in FIG.
At this point, the bending angle of the light 12 by the Fresnel lens screen 14 is insufficient, and the light 12 is obliquely incident on the lenticular lens screen 15 as shown in FIG.

Thus, the lenticular lens screen 1
Among the lights 12 that are obliquely incident on the light beam 5, there is light 12 that does not enter the lens 15b but is blocked by the black stripe 16 and does not exit from the lenticular lens screen 15. If the light 12 is not emitted from the lenticular lens screen 15, the image on the screen becomes dark.

On the other hand, the lenticular lens screen 15
Since the incident angle of the light 12 with respect to is different depending on the position on the screen, so-called luminance shading occurs in which the luminance of the image differs depending on the position on the screen.
Therefore, in the conventional example shown in FIGS. 2 and 3, a high quality image could not be displayed.

[0009]

According to another aspect of the rear projector screen of the present invention, the central axis of the lens 15a on the incident side of the light 12 of the image to be displayed and the central axis of the lens 15b on the outgoing side are displaced from each other. A lenticular lens screen 15 is provided.

A rear projector screen according to a second aspect of the present invention is the rear projector screen according to the first aspect, wherein the displacement amount differs depending on the position on the lenticular lens screen 15.

A rear projector screen according to a third aspect is the rear projector screen according to the second aspect, wherein the displacement amount is zero at the central portion x of the lenticular lens screen 15 and increases toward both end portions y. There is.

A rear projector screen according to a fourth aspect is the rear projector screen according to the second aspect, wherein the displacement amount increases from one end side to the other end side of the lenticular lens screen 15.

[0013]

In the screen for a rear projector according to the present invention, even if the black surface 16 is provided on a portion of the exit surface of the lenticular lens screen 15 other than the lens 15b, the light of the image obliquely incident on the lenticular lens screen 15 is provided. 12 can be emitted from the lens 15b on the emission side without being blocked by the black surface 16.

Further, even when the image light 12 is obliquely incident on both ends y of the lenticular lens screen 15 by using a projection lens having a short focus, the lenses 15a and 15b are provided.
By setting the displacement amount between the central axes of the two to zero at the central portion x of the lenticular lens screen 15 and increasing toward the both end portions y, the light 12 of the image is emitted from the lens 15b on the emission side without being blocked by the black surface 16. It can be emitted.

Further, even when the incident angle of the light 12 of the image is increased from one end side to the other end side of the lenticular lens screen 15 by using the oblique projection type optical system, the central axes of the lenses 15a and 15b. By increasing the amount of displacement between the lenticular lens screens 15 from one end side to the other end side, the light 12 of the image can be emitted from the emission side lens 15b without being blocked by the black surface 16.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first to third embodiments of the present invention will be described below with reference to FIG. The components corresponding to those of the conventional example shown in FIGS. 2 and 3 are designated by the same reference numerals.

First, the first embodiment will be described. Also in the first embodiment, at the point x in FIG. 2 which is the central portion of the lenticular lens screen 15, the lenses 15a on the incident side and the emitting side of the light 12 are, as in the conventional example shown in FIGS. 1
The central axes of 5b coincide with each other.

However, in the first embodiment, at the portions other than the central portion of the lenticular lens screen 15, for example, at the y points in FIG. 2 which are both end portions, as shown in FIG. 1, the central axes of the lenses 15a and 15b. Are displaced from each other. Moreover, the amount of this displacement is the lenticular lens screen 15
It grows toward both ends. Except for this point, the first embodiment has substantially the same configuration as the conventional example shown in FIGS.

In the first embodiment as described above, as is apparent from FIG. 1, even the light 12 obliquely incident on the lenticular lens screen 15 has its optical axis bent and enters the lens 15b, and the black stripe 16 is emitted. The light is normally emitted from the lens 15b without being blocked by. Therefore, in the first embodiment, even if the projection lens 13 having a short focus is used, it is possible to display a high-quality image with less brightness shading.

Next, a second embodiment will be described. In the second example, the amount of displacement between the central axes of the lenses 15a and 15b increases from one end side to the other end side of the lenticular lens screen 15. Except for this point, this second embodiment also has substantially the same configuration as the conventional example shown in FIGS. Therefore, in this second embodiment,
Even if the oblique projection optical system is used, it is possible to display a high-quality image with less brightness shading.

Next, a third embodiment will be described. In the third embodiment, the lenses 15a, 1a and 1b are provided as in the first embodiment.
The amount of displacement between the central axes of 5b is zero in the central part of the lenticular lens screen 15, and increases from the two ends of the lenticular lens screen 15 to two.
The sheets are superposed with the generatrixes of the lenses 15a and 15b orthogonal to each other, and instead, the Fresnel lens screen 14 is not used.

In the third embodiment as described above, since the two lenticular lens screens 15 can also have the function of the Fresnel lens screen 14, not only high-quality images can be displayed, but also the structure is improved. Is also easy.

[0023]

In the screen for a rear projector according to the present invention, even when the image light is obliquely incident on the lenticular lens screen by using a projection lens having a short focus or an oblique projection type optical system, the black color of the lenticular lens screen is used. Since the light of the image can be emitted from the lens on the emission side without being blocked by the surface, it is possible to display a high-quality image with less brightness shading.

[Brief description of drawings]

FIG. 1 is an enlarged side view of essential parts of first to third embodiments of the present invention.

FIG. 2 is a schematic side view of a rear projector in which a conventional example of the present invention is used.

FIG. 3 is an enlarged side view of a main part of a conventional example, (a) showing a central part of the lenticular lens screen, and (b) showing an end part of the lenticular lens screen.

[Explanation of symbols]

 12 light 15 lenticular lens screen 15a lens 15b lens

Claims (4)

[Claims] 1. A screen for a rear projector comprising a lenticular lens screen in which a central axis of a lens on a light incident side of an image to be displayed and a central axis of a lens on an outgoing side are displaced from each other. 2. The rear projector screen according to claim 1, wherein the amount of displacement varies depending on the position on the lenticular lens screen. 3. The rear projector screen according to claim 2, wherein the amount of displacement is zero at the center of the lenticular lens screen and increases toward both ends. 4. The rear projector screen according to claim 2, wherein the amount of displacement increases from one end side to the other end side of the lenticular lens screen.