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:
Mar. 22, 1988
Filed:
Dec. 09, 1985
Applicant:
Inventors:
Tadashi Ookawa, Funabashi, JP;
Hiroyuki Tomita, Funabashi, JP;
Masataka Yahara, Chiba, JP;
Masaharu Muramatu, Chiba, JP;
Sumio Kobayashi, Funabashi, JP;
Hiroshi Sugai, Sakura, JP;
Hisakazu Ninomiya, Funabashi, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G01D / ;
U.S. Cl.
CPC ...
2502 / ; 2502 / ;
Abstract
A fixed slit plate and a rotary slit plate which is secured to a rotating shaft are provided between two photoconductive elements and a light emitting element, and the two photoconductive elements provide two outputs which have the phase difference .pi. therebetween. These two outputs thus provided are added to extract the dc component, thereafter exerting feedback control over the light emitting element such that this dc component is maintained at a constant level.