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:
Jun. 28, 1983
Filed:
Jul. 25, 1980
Koji Hirakura, Yokohama, JP;
Yasuo Sawada, Sayama, JP;
Kenta Watase, Tokyo, JP;
Takeshi Iijima, Yokohama, JP;
Ricoh Company, Ltd., , JP;
Abstract
A toner concentration control system for use in electrophotographic copying machines or the like, wherein light from a single light source is simultaneously detected by two photosensors, or by two sensing portions of a single photosensor, the light striking one of the photosensors (or portions) directly and the other after being reflected from developer comprising toner and carrier particles as the developer passes a viewing window in a chute provided for the transport thereof within the copying machine, the intensity of the reflected light being inversely proportional to the concentration of toner in the developer, whereby, by comparison of the output of the photosensors (or portions) by conventional means, the concentration of toner in the developer can be determined and adjusted, the photosensors (or portions) having been carefully selected as a pair of their essentially identical characteristics and response to ambient conditions so that, for example, their parallel deterioration with time or their identical response to changes in temperature will not adversely affect the accuracy of the toner-concentration determination, the portion of the embodiment comprising the light paths, the photosensors, the light source and the external surface of the viewing window being completely sealed from the remainder of the interior of the copying machine, thereby eliminating the adverse affects on measurement and long-term reliability of inevitable airborne particles of developer.