Reduced field angle projection display system
First Claim
1. A rear projection display system comprising:
- a) a housing;
b) a screen disposed at a front side of the housing;
c) a light engine positioned generally in an upper region of the housing to facilitate heat dissipation, the light engine being adapted to project an off-axis beam of light to form a projected image;
d) a first mirror positioned in a lower region of the housing generally opposite the light engine, the first mirror being adapted to reflect the projected image to form a first reflected image that is reflected upward and away from the screen;
e) a second mirror positioned generally opposite the screen, the second mirror being adapted to reflect the first reflected image to form a second reflected image that is directed towards the screen in an off-axis manner with respect to a screen normal, the second reflected image being formed with light rays having a desired angular range with respect to the screen normal to allow collimation via total internal reflection; and
, f) a total internal reflection Fresnel lens positioned generally parallel and adjacent to the screen, the Fresnel lens being adapted to reflect the light rays of the second reflected image along the direction of the screen normal to form a final image that is displayed on the screen.
10 Assignments
0 Petitions
Accused Products
Abstract
A rear projection display system (RPDS) and associated optical system are described with a reduced field angle. The RPDS includes a screen and a housing. The optical system includes a light engine, a first mirror, a second mirror and a Fresnel lens arranged to achieve a thin housing. The light engine is generally disposed in an upper region of the housing, and projects light onto the first mirror, which can be located at a bottom portion of the housing. The first mirror reflects the projected light onto the second mirror, which in turns reflects the light towards the Fresnel lens, which transfers the light onto the screen. A total internal reflection Fresnel lens is used to reduce cost and complexity without sacrificing image quality and housing thinness. An image processing device can also be used to compensate for geometric and optical distortions in the final image displayed on the screen.
107 Citations
40 Claims
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1. A rear projection display system comprising:
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a) a housing;
b) a screen disposed at a front side of the housing;
c) a light engine positioned generally in an upper region of the housing to facilitate heat dissipation, the light engine being adapted to project an off-axis beam of light to form a projected image;
d) a first mirror positioned in a lower region of the housing generally opposite the light engine, the first mirror being adapted to reflect the projected image to form a first reflected image that is reflected upward and away from the screen;
e) a second mirror positioned generally opposite the screen, the second mirror being adapted to reflect the first reflected image to form a second reflected image that is directed towards the screen in an off-axis manner with respect to a screen normal, the second reflected image being formed with light rays having a desired angular range with respect to the screen normal to allow collimation via total internal reflection; and
,f) a total internal reflection Fresnel lens positioned generally parallel and adjacent to the screen, the Fresnel lens being adapted to reflect the light rays of the second reflected image along the direction of the screen normal to form a final image that is displayed on the screen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An optical system for use in a rear projection display system having a housing and a screen, wherein the optical system comprises:
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a) a light engine positioned in an upper portion of the optical system, the light engine being adapted to project a beam of light to form a projected image;
b) a first mirror positioned in a lower portion of the optical system, the first mirror being adapted to reflect the projected image to form a first reflected image that is reflected upward and away from the screen;
c) a second mirror positioned to one side of the first mirror, the second mirror being adapted to reflect the first reflected image to form a second reflected image with light rays having a desired angular range with respect to a screen normal of the screen to allow collimation via total internal reflection; and
,d) a total internal reflection Fresnel lens, positioned generally opposite the second mirror, the Fresnel lens being adapted to reflect the light rays of the second reflected image along the direction of the screen normal to form a final image that is displayed on the screen. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method for producing a final image on a screen of a rear projection display system, the display system having a housing, wherein the method comprises:
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positioning a light engine in an upper portion of the housing for projecting a beam of light to form a projected image;
positioning a first mirror in a lower portion of the housing for reflecting the projected image to form a first reflected image that is reflected upward and away from the screen;
positioning a second mirror to one side of the first mirror for reflecting the first reflected image to form a second reflected image with light rays having a desired angular range with respect to a screen normal of the screen to allow collimation via total internal reflection; and
,positioning a total internal reflection Fresnel lens generally opposite the second mirror for reflecting the light rays of the second reflected image along the direction of the screen normal to form the final image that is displayed on the screen. - View Dependent Claims (35, 36, 37, 38, 39, 40)
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Specification