The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 24, 2009
Filed:
Jul. 24, 2007
Etsuro Kawakami, Akishima, JP;
Yasuyuki Tejima, Tokyo, JP;
Etsuro Kawakami, Akishima, JP;
Yasuyuki Tejima, Tokyo, JP;
Casio Computer Co., Ltd., Tokyo, JP;
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.