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:
Jul. 28, 2009
Filed:
Nov. 13, 2006
Applicants:
Hirofumi Takei, Yokohama, JP;
Naoya Kaneda, Chigasaki, JP;
Tadanori Okada, Utsunomiya, JP;
Inventors:
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04N 5/225 (2006.01);
U.S. Cl.
CPC ...
Abstract
A light quantity control device includes a diaphragm for controlling an incident light quantity and an ND filter insertable into and retractable from an effective ray in a plane approximately perpendicular to an optical axis, and inserts the ND filter into the effective ray before small-aperture diffraction occurs, and also controls the amount of relative movement between the diaphragm and the ND filter to prevent occurrence of shading due to an edge of the ND filter and a variation in brightness during the insertion of the ND filter.