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. 01, 1990
Filed:
Jun. 24, 1988
Masaru Hidaka, Nara, JP;
Hirotsugu Murashima, Yamatotakada, JP;
Masao Takuma, Toyonaka, JP;
Toshinobu Haruki, Shijonawate, JP;
Kenichi Kikuchi, Osaka, JP;
Sanyo Electric Co., Ltd., , JP;
Abstract
In an automatic focusing apparatus of a video camera, a first focus evaluating value which steeply changes and a second focus evaluating value which gently changes relative to the position of a lens, are detected in response to a video signal obtained in an image sensing circuit (4). A switching circuit (19) alternately selects the first and second focus evaluating values every one field to apply the same to in-focus state detecting circuits (20, 21), respectively. The in-focus state detecting circuits (20, 21), together with a focusing motor control circuit (10), perform an automatic focusing operation by hill-climbing control. In addition, a calculating circuit (22) calculates the relative ratio of the first focus evaluating value to the second focus evaluating value. The focusing motor control circuit (10) sets the rotational speed of a focusing motor (3) to a normal speed when the calculated relative ratio is smaller than a predetermined value while setting the rotational speed of the focusing motor (3) to a low speed when it is larger than the predetermined value. Therefore, a lens (1) is moved at low speed when the focusing lens is in the vicinity of the in-focus position while being moved at high speed when it is in the defocused state.