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Patent Searching and Data


Title:
PROJECTION TYPE DISPLAY DEVICE AND LIGHTING DEVICE
Document Type and Number:
Japanese Patent JPH04142528
Kind Code:
A
Abstract:

PURPOSE: To remove diverged light and to improve the contrast ratio of a projection image by converging the light emitted by a light source by using an elliptic mirror and increasing the convergence efficiency, and providing a prism in a specific shape at its 2nd focus position.

CONSTITUTION: The light source 1 is arranged at the 1st focus position of the elliptic mirror 2 and the light emitted from the light source 1 is reflected by the elliptic mirror 2, made incident on the opening part of a stop 3 from the bottom surface of a conic prism 4 provided with its bottom surface, and projected as uniform luminous flux; and the light is collimated by a converging lens 5, a 2nd stop 8 as a means for removing scattered light removes the scattered light, and the light is projected on a screen through a projection lens 9. As shown in an extended figure of the projection light source system, the light source 21 is arranged at the 1st focus of the elliptic mirror 22 and the opening part of the stop 23 and the bottom surface of the prism 24 are arranged at the 2nd focus. The conical prism is so shaped that even incident light having the largest angle θ2 of incidence in incident light reflected by the elliptic mirror is reflected totally in the prism, and consequently a high light emission light source which is close to an ideal spot light source is obtained almost without light quantity loss.


Inventors:
OI, Yoshiharu
Korishima, Tomonori
Hirai, Yoshinori
Application Number:
JP1990000265059
Publication Date:
May 15, 1992
Filing Date:
October 04, 1990
Export Citation:
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Assignee:
ASAHI GLASS CO LTD
International Classes:
G03B21/20; G02F1/13; G02F1/1335; G02F1/13357; G03B21/14; G03B33/12; (IPC1-7): G03B21/20