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:
Dec. 28, 1993
Filed:
Sep. 23, 1992
Daisuke Hata, Funabashi, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A control system for vari-focal lens can keep a vari-focal lens in focus during magnification change, and can conduct quick focusing even if a distance measurement is not possible in a phase difference detection method. A focusing correction calculation circuit calculates two data, one of which is a focusing lens position datum obtained by a focusing lens position detection device and the other of which is a magnification changing lens group position datum obtained by a magnification changing lens position detection device, to obtain a correction amount datum and a correction focusing direction datum. Another calculation circuit obtains a phase difference datum based on a phase difference detection datum detected by a phase difference detector. If a judgement circuit judges either that the distance measurement is not possible, that the phase difference is under calculation, or that the phase difference is under detection, a focusing correction is effected based on the correction amount datum and the correction focusing direction datum. If the judgement circuit judges otherwise, the focusing is effected based on the datum obtained from the phase difference detection datum.