Zoom lens and image projection apparatus having the same

Details Zoom lens and image projection apparatus having the same Zoom lens and image projection apparatus having the same

2008-05-13

2009-08-18

Lester, Evelyn A. (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S681000, C359S682000, C359S683000, C359S686000, C359S689000, C359S691000, C359S713000, C359S714000, C359S715000, C359S716000, C359S717000, C359S762000, C359S649000

Reexamination Certificate

active

07576923

ABSTRACT:
A zoom lens comprises a plurality of lens units including a first lens unit disposed most adjacent to an enlargement side and having negative refractive power, wherein one or more lens units of the plurality of lens units are moved in the direction of the optical axis thereof during magnification change, and wherein the first lens unit includes a 1-1st lens unit comprising at least one lens of negative refractive power and moved during focusing and a 1-2nd lens unit having positive refractive power, and fixed during focusing.

REFERENCES:
patent: 4124274 (1978-11-01), Tanaka et al.
patent: 6580564 (2003-06-01), Nagahara
patent: 6888682 (2005-05-01), Kawakami
patent: 7190528 (2007-03-01), Inoko
patent: 2001/0050818 (2001-12-01), Wada et al.
patent: 200410007929.3 (2004-09-01), None
patent: 10-186235 (1998-07-01), None
patent: 2001-235679 (2001-08-01), None
patent: 2002-357771 (2002-12-01), None
patent: 2004-226803 (2004-08-01), None
First Office Action issued on May 11, 2007 for Chinese patent application No. 200610004104.5 (with English translation).

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