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. 06, 1993
Filed:
May. 22, 1992
Ricoh Company, Ltd., Tokyo, JP;
Abstract
Pulse light is emitted by controlling the operation of a driving circuit by a microcomputer and is irradiated to a photographed object. Light reflected on the photographed object is received by a semiconductor optical position detector. First and second current outputs having a current ratio are inputted to first and second detecting circuits within an AF signal processing circuit in accordance with a light receiving position corresponding to a distance of the object. The first and second detecting circuits logarithmically transform changing amounts of the first and second current outputs. A differential detecting circuit calculates a difference between changing amounts of outputs of the first and second detecting circuits, and outputs a distance measuring signal to the microcomputer. A light receiving element measures the intensity of external light and an error in the distance measuring signal caused by the external light is corrected by the microcomputer on the basis of the above results.