Method of controlling surface potential of photoconductive element
US4870460A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 4, 1987 |
| Grant date | Sep 26, 1989 |
| Priority date | — |
| Expiry date | Dec 4, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S430/102
- WIPO fieldOptics
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.