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:
Jan. 03, 1989
Filed:
Jul. 27, 1987
Kiyoshi Iizuka, Kanagawa, JP;
Takashi Suzuki, Kanagawa, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A focusing screen for observing an image formed by an objective lens is constructed of a liquid crystal layer, having a dynamic scattering effect, sandwiched between a pair of parallel transparent electrodes. At least one of the transparent electrodes is divided into a plurality of discrete parts. The discrete electrode parts are connected as independent groups through a switch mechanism to a driving circuit. The switch mechanism permits one or more of the groups to act as different elements in response to an applied voltage, depending on the F value of the lens. Accordingly, the scattering degree of the focusing screen varies as a function of the F value and not the applied voltage.