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:
Sep. 26, 1989
Filed:
Dec. 04, 1987
Masahide Harada, Tokyo, JP;
Kazuhiro Kimura, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A control method applicable to an electrophotographic copier for protecting the background of copies against smears due to a residual potential on a photoconductive element. Before a visible pattern is produced, the photoconductive element is charged by a lower potential than a charging potential which is adapted to form a document image and, then, it is discharged. Potential remaining on the photoconductive element which has been discharged is developed to produce the visible pattern, and the density of this pattern is optically detected. Based on the density level of the visible pattern detected, at least one of a developing bias potential, a charging potential and an exposing potential which are to form a document image is corrected. In the event of producing the visible pattern, the potential remaining on the photoconductive element is developed by a developing bias potential which has been corrected on the bias of visible pattern density level detected immediately before. In a multi-color electrophotographic copier which uses a plurality of colors of toner, the visible pattern is produced by using one particular color of toner which is advantageously black toner.