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:
Dec. 18, 2007
Filed:
Nov. 18, 2005
Youhei Nagai, Tokyo, JP;
Yasuhiko Abe, Toda, JP;
Youhei Nagai, Tokyo, JP;
Yasuhiko Abe, Toda, JP;
Nidec Copal Corporation, Tokyo, JP;
Abstract
A zoom lens is equipped with: a first lens group having an overall negative refractive power and a second lens group having an overall positive refractive power in sequence from the object side to the image plane side. Zoom magnification is changed from a wide-angle end to a telephoto end by moving the first lens group to the image plane side and then reversing the motion to the object side while the second lens group is moved to the object side. The condition (1) 0.90<=(DG+DG)/fw<=2.30 and the condition (2) 0.5<=|fG|/fG<=1.6 are met, where DGis the thickness of the first lens group; DGis the thickness of the second lens group; fw is the focal length of the lens system at the wide-angle and; fGis the focal length of the first lens group; and fGis the focal length of the second lens group. With above structure, the power arrangements for the first and second lens groups are set appropriately providing a zoom magnification ratio of approximately 3× beside making the design of the zoon lens compact and thin.