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:
Mar. 04, 1980
Filed:
Jul. 18, 1978
Hideharu Sato, Higashikurume, JP;
Nihon Beru-Haueru Kabushiki Kaisha (Bell & Howell Japan, Ltd.), Higashimurayama, JP;
Abstract
An automatic focus adjusting device for use with an optical instrument hag a focusable objective lens which is adjusted by optical and electronic components of the instrument, such components determining the distance of an object by comparing images of separate scanning and reference optical systems. The device of the present invention has a low-reduction filter screen placed across part of each light path of the two optical systems. The filters provide an overriding apparent contrast to low-contrast object fields to cause the system to adopt a pre-set focus distance, but do not interfere with normal automatic focusing where object field contrast is adequate for normal system operation. Manual adjustment of the filter spacing varies the pre-set, low-contrast focus to any desired object distance setting. Five to ten percent light reduction in the screened part of each filter is adequate.