Zoom lens and projector using zoom lens

Details Zoom lens and projector using zoom lens Zoom lens and projector using zoom lens

2007-07-24

2009-02-24

Mack, Ricky L (Department: 2873)

Optical: systems and elements

Lens

With variable magnification

C359S687000, C359S688000

Reexamination Certificate

active

07495841

ABSTRACT:
To provide a high performance compact zoom lens with a small lens aperture which projects an image from a light valve such as a DMD (Digital Micromirror Device) in which an image is formed by changing reflecting directions of light on to a screen or the like in an enlarged fashion, according to the invention, there is provided zoom lens comprising, in order from a magnifying side thereof, a first lens group having a positive or negative refractive power as a whole, a second lens group having a negative refractive power as a whole, a third lens group having a positive or negative refractive power as a whole and a fourth lens group having a positive refractive power as a whole, wherein changing the magnification of the whole lens system thereof is attained by configuring such that the first lens group is left fixed while a magnification varying operation is effect, the second lens group, the third lens group and the fourth lens group are made to move on an optical axis.

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Japanese Office Action dated Jun. 3, 2008 and English translation thereof issued in counterpart Japanese Appln. No. 2006-207388.
“Digital Micromirror Device” downloaded from Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/digital—micromirror—device., downloaded Jan. 3, 2008, 2 pages.
“DMD (Digital Micro-Mirror Device)”, About.com: Home Theater http://hometheater.about.com/od/televisionbasics/g/dmddef.htm?p=1, downloaded Jan. 3, 2008, 1 page.
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