Optical: systems and elements – Projection screen – With reflector or additional screen
Reexamination Certificate
1995-09-05
2001-08-14
Mahoney, Christopher E. (Department: 2851)
Optical: systems and elements
Projection screen
With reflector or additional screen
C359S457000
Reexamination Certificate
active
06275334
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a projector screen used as an image-displaying medium, and more particularly to a projector screen having an improved horizontal view angle.
2. Description of the Related Art
The direct-view type screen of a conventional image-displaying means, for example, a television, uses a cathode-ray tube (CRT). For larger screens, however, the use of a cathode-ray tube is not practical because it is difficult to make a large CRT. Even if technical problems associated with making large CRTs could be overcome, the weight of a CRT also increases accordingly, so that it is difficult to transport and assemble a large CRT into a finished device. Therefore, an image projection system such as a projection television or video projector has been developed.
FIGS. 1 and 2
show two examples of a conventional image projection system. Such a system generates an image by using a specially manufactured small CRT
1
or image-displaying means
2
such as a liquid crystal display element or a polymer dispersed liquid crystal. Then, the generated image is amplified by using an optical lens, e.g., projection lens
3
, for projection onto a large screen.
Conventionally, there are two types of image projection systems, i.e., a frontal-projection type projector (front type) and a rear-projection type projector (rear type). Typical rear-projection type projectors, such as those shown in
FIGS. 1 and 2
, have advantages in that they can be manufactured with a slimmer body than the frontal-projection type projector, and can provide a displayed image of better brightness.
The rear type projector is used for various kinds of apparatus such as a flight simulator, a traffic signal light, a video monitor, a microfilm reader, and a general rear-projection type display using a film medium for generating an image which can be observed by a user. These apparatus include a projector which generates an image on a screen by projecting light, from an image source situated behind the screen, along a projection axis to the front of the screen. A viewer is situated in front of the screen, and when there are many such viewers, the horizontal viewing angle must be large to allow all of the viewers to see a bright image. Also, it is desirable to have a large horizontal viewing angle so that a viewer can be situated at positions other than directly in front of the screen.
FIG. 3
is a schematic perspective view showing the cross-sectional structure of a screen for a conventional projector. To display an image of nearly uniform luminance over a wide viewing angle by deflecting the rays emitted from an image source, the screen is equipped with Fresnel lens
11
for generating parallel light by receiving the light magnified by a projection lens. In front of Fresnel lens
11
, there are plural lenticular lenses
12
extending in parallel with one another (hereafter collectively called a lenticular lens system). The lenticular lens system serves as a light-spreading means for forming an image by spreading the parallel light passed through Fresnel lens
11
. In front of the lenticular lens system, namely, at the viewer's side, is screen protection panel
13
of an acrylic material. Also, between the rear side of screen protection panel
13
and the front side of the lenticular lens system, projecting part
12
a
of a predetermined height is formed for absorbing part of light spread from a convex surface of the individual lenticular lenses
12
. Projecting part
12
a
is formed by black stripes
12
b
painted with an opaque ink or the like formed between adjacent lenticular lenses
12
forming the lens system on the tip of projecting part
12
a
. This allows the contrast of the image formed in front of lenticular lens
12
to be improved.
However, in a conventional screen for a projector, projecting part
12
a
having black stripe
12
b
extends outward from the surface of the lenticular lens system so that a light-scattering angle of the individual lenticular lenses
12
of the lenticular lens system is limited. See FIG.
4
. This limited light-scattering angle restricts the horizontal angle for viewing an image on the screen.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a projector screen having an improved horizontal viewing angle.
Accordingly, to achieve the above object, there is provided a projector screen comprising: a Fresnel lens for collimating incident light from a projection lens equipped in a light projection apparatus; plural lenticular lenses connected and extending in parallel with respect to one another for forming and spreading an image from the collimated light by the Fresnel lens; and a screen protection panel for protecting a screen installed adjacent to the lenticular lens, wherein the screen protection panel is equipped with light-absorbing means for absorbing light spread by the lenticular lens.
In the aforesaid screen for a projector according to the present invention, it is preferable that the light-absorbing means is a black stripe on the tip of a projecting part formed on the side of the screen protection panel facing each lens-connecting part of the lenticular lens, and the convex surface of each lenticular lens extends further toward the viewer than the black stripe formed on the projecting part which serves as the light absorbing means.
REFERENCES:
patent: 3523717 (1970-08-01), Glenn, Jr.
patent: 4666248 (1987-05-01), van de Ven
patent: 4859027 (1989-08-01), Kishida
patent: 4979801 (1990-12-01), Park
patent: 5121252 (1992-06-01), Okada et al.
patent: 5448401 (1995-09-01), Takuma et al.
patent: 5457572 (1995-10-01), Ishii et al.
patent: 5870224 (1999-02-01), Saitoh et al.
patent: 85 1 04899 A (1987-04-01), None
Mahoney Christopher E.
Samsung Electronic Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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