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:
Sep. 21, 1976
Filed:
Oct. 23, 1973
Tamotsu Karasawa, Kawasaki, JA;
Canon Kabushiki Kaisha, Tokyo, JA;
Abstract
A light-modulating device having an extended range of light modulation comprising a mechanical variable diaphragm means and a neutral density filter arranged to optically cover the aperture opening of said diaphragm means, said filter being characterized as including two regions, one of which is a central uniform density region which is centered at the optical axis, while in the other region contiguous to the central region, the density is decreased with radius. In this manner the amount of light is varied in passing through the light-modulating device as a function of the area of the aperture opening and the transmittance of effective area of the filter. A method of producing filters of such characteristics are also disclosed.