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:
Oct. 07, 2003
Filed:
May. 01, 2002
Katsumi Motomura, Asaka, JP;
Takeshi Kubota, Minami-Ashigara, JP;
Fuji Photo Film Co., Ltd., Kanagawa, JP;
Abstract
An electronic flash device of an automatic light adjusting type includes a main capacitor for storing charge at a high voltage. A flash discharge tube generates flash light upon discharging the main capacitor therewith. A light adjusting circuit adjusts a light amount of the flash light by feedback. The light adjusting circuit includes a reflected light measuring unit for outputting an integration voltage for representing a light amount of reflected light from a photographic field illuminated with the flash light. A thyristor as non-contact switch short-circuits terminals of the main capacitor upon being turned on, to quench emission of the flash light in the flash discharge tube. A turn-on capacitor is charged by a current of discharge in response to the emission of the flash light, and is discharged when the integration voltage comes up to a prescribed level, to turn on the thyristor responsively. A control transistor keeps the reflected light measuring unit disabled while the turn-on capacitor is initially charged, and enables the reflected light measuring unit after the integration voltage comes up to a predetermined level.