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. 22, 1987
Filed:
Mar. 04, 1985
Applicant:
Inventors:
Fumitaka Kotaka, Saitama, JP;
Takanori Maeda, Saitama, JP;
Assignee:
Pioneer Electronic Corporation, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
G01J / ;
U.S. Cl.
CPC ...
356123 ; 250201 ; 369 45 ;
Abstract
A focus error detector comprises an inner group of light detector elements formed in a circular area about a focus point of an illumination beam for generating a first focus error signal. A second group of light detector elements formed in an annular-shaped area around the circular area for generating a second focus error signal, an amplifier for amplifying the second error signal, and an adder for combining the first and second focus error signals to generate a composite focus error signal.