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:
Apr. 26, 2011
Filed:
Dec. 13, 2002
Yasunori Murata, Tokyo, JP;
Takeshi Koyama, Tokyo, JP;
Yasunori Murata, Tokyo, JP;
Takeshi Koyama, Tokyo, JP;
Canon Kabushiki Kaisha, , JP;
Abstract
An optical performance is deteriorated by a minute phase difference of transmission wave front of an ND filter. In a light quantity adjusting device which includes an ND filter (P) for attenuating a quantity of light passing through an aperture formed by diaphragm blades (Sand S) and in which a cover ratio of the aperture by the ND filter (P) is changed, setting is conducted such that a phase difference between lights with a predetermined wavelength λ which pass through regions (NNand N) of the ND filter (P) with different transmittances inside the aperture becomes substantially 0λ, substantially 1λ, or substantially 2λ in a state in which the aperture is completely covered with the ND filter (P).
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile