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:
Jul. 02, 1985
Filed:
Oct. 27, 1983
Hitachi, Ltd., Tokyo, JP;
Abstract
Disclosed is an exposure amount control device for a copying machine comprising an exposure amount control circuit for controlling an exposure amount by controlling light of the exposure lamp for illuminating an original document to be copied and a digital light control signal generator for supplying a digital light control signal of a variable duty factor to the exposure amount control circuit. The digital light control signal generator includes a light intensity increase/decrease setting circuit and an oscillator for generating an oscillation output of a variable oscillation period in accordance with a light intensity signal from the light intensity increase/decrease setting circuit. The oscillation output of the oscillator is converted to an on-off light signal, which is supplied to the exposure amount control circuit as the digital light control signal. Thus, the digital light control signal generator is perfectly electrically isolated from a primary power supply circuit of the exposure amount control circuit and a highly safe exposure amount control device with a stable control ability due to an on-off light signal is provided.