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:
May. 16, 1989
Filed:
Oct. 06, 1987
Daisuke Hata, Funabashi, JP;
Susumu Iguchi, Kawasaki, JP;
Yoshimi Ohno, Kawasaki, JP;
Kazumasa Aoki, Tokyo, JP;
Takayuki Hatase, Yokohama, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
An auto-focus arithmetic device suitable for use in a photographic camera is provided. The device includes a photographic lens which is movable along a predetermined optical axis and a CCD for detecting light coming from a subject of interest through the lens. An arithmetic unit for determining the direction and amount of movement of the lens with respect to the subject of interest based on a detection signal from the CCD is provided. The arithmetic unit includes an integer portion calculating sub-unit for calculating an integer portion of the detection signal and a fractional portion calculating sub-unit for calculating a fractional portion of the detection signal. The fractional portion calculating sub-unit remains deactivated as long as the detected amount of discrepancy from the in-focus condition is larger than a predetermined level; however, it is activated when the detected amount of discrepancy becomes equal to or less than the predetermined level. In this manner, in accordance with the present invention, the integer and fractional portion calculating sub-units are used alternately.