Electrophotographic apparatus
US3977778A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 3, 1974 |
| Grant date | Aug 31, 1976 |
| Priority date | — |
| Expiry date | Jul 3, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/043
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
In electrophotographic apparatus for producing positive copies of both positive and negative originals with toner of one polarity by establishing and developing an electrostatic latent image on a light-sensitive member that is precharged to a first polarity for positive originals and to the opposite polarity for negative originals, wherein means are provided for exposing the precharged member to an optical image of the original and for controlling the exposure by varying the amount of light used, a two-position changeover switch for reversing the operation of the exposure controller depending on whether the original is positive or negative. This changeover switch, and also a switch for reversing the charging polarity of means for precharging the light-sensitive member, may be controlled by photoelectric means for determining whether the original is positive or negative by sensing the optical density of a marginal portion provided on the original.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.