Projection-type apparatus

Details Projection-type apparatus Projection-type apparatus

1994-05-04

1997-09-30

Dowling, William

Optics: image projectors

Cabinet encloses projector and one side of screen

Reflector between lamp and screen

353 78, 353 97, G03B 2128

Patent

active

056719930

ABSTRACT:
A retro-focus type lens is provided from a large conjugate side with a first lens group having a negative refracting power, a second lens group having a positive refracting power which is spaced away from the first lens group at an air interval D1, and a third lens group having a positive refracting power. The following conditions are satisfied when focal lengths of the first lens group, the second lens group, the third lens group, and a total lens system are assumed respectively as f1, f2, f3, and f:

REFERENCES:
patent: 4257694 (1981-03-01), Reinhard
patent: 4544946 (1985-10-01), VanBreemer
patent: 4578710 (1986-03-01), Hasegawa
patent: 4708435 (1987-11-01), Yata et al.
patent: 4963016 (1990-10-01), Heijnemans et al.
patent: 5278595 (1994-01-01), Nishida et al.
patent: 5285287 (1994-02-01), Shikama
patent: 5311227 (1994-05-01), Takayasu et al.

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