Zoom lens and projector

Details Zoom lens and projector Zoom lens and projector

2007-10-18

2010-02-23

Spector, David N (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S686000

Reexamination Certificate

active

07667898

ABSTRACT:
A zoom lens includes a first lens group having negative power, a second lens group having positive power, a third lens group having positive power, and a fourth lens group having positive power, disposed in this order from the enlargement side to form the entire structure. At the time of zooming from the wide angle side to the telephoto side, the first lens group shifts from the enlargement side to the reduction side and the second and third lens groups shift from the reduction side to the enlargement side and the fourth lens group is fixed. The overall length of the zoom lens becomes the maximum at the wide angle end.

REFERENCES:
patent: 4687302 (1987-08-01), Ikemori et al.
patent: 5867326 (1999-02-01), Yamamoto
patent: 6970298 (2005-11-01), Itoh
patent: A 2001-124989 (2001-05-01), None
patent: A 2001-188172 (2001-07-01), None
patent: A 2004-085979 (2004-03-01), None
patent: A 2004-279958 (2004-10-01), None
patent: A 2005-338702 (2005-12-01), None
patent: A-2006-39033 (2006-02-01), None

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