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:
May. 05, 2009
Filed:
May. 02, 2007
Etsuro Kawakami, Tokyo, JP;
Yasuyuki Tejima, Itabashi, JP;
Etsuro Kawakami, Tokyo, JP;
Yasuyuki Tejima, Itabashi, JP;
Casio Computer Co., Ltd., Tokyo, JP;
Abstract
There is provided a compact zoom lens having a small lens aperture which an image from a light valve such as a DMD is projected on to a screen in an enlarged scale. There is provided a zoom lens comprising, in order from a magnifying side, a first lens group having a negative refractive power as a whole, a second lens group having a positive or negative refractive power as a whole, a third lens group having a positive refractive power as a whole and a fourth lens group having a positive refractive power as a whole, wherein a variable power as a whole lens system thereof is established by configuring such that the fourth lens group is left fixed while a variable power is effected, and the first lens group, the second lens group and the third lens group are made to move on the optical axis.