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:
Nov. 29, 1977
Filed:
May. 17, 1976
Applicant:
Inventor:
Tsukumo Nobusawa, Minami Oizumi, JA;
Assignee:
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JA;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G03B / ; G01C / ;
U.S. Cl.
CPC ...
354 25 ; 250204 ; 356-4 ;
Abstract
In an automatic focusing system having an objective spaced an adjustable distance from an image plane, two variable frequency oscillators, each controlled by a separate photoconductor element, produce two variable-frequency signals that have substantially the same frequency when light passing through the objective is brought into focus at the image plane. The two variable-frequency signals are compared, and, upon detecting a difference in frequency between them, the spacing between the objective and the image plane is adjusted to a relative position at which the frequencies thereof are substantially the same.