Copying method and apparatus
US4413899A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 1981 |
| Grant date | Nov 8, 1983 |
| Priority date | — |
| Expiry date | Jan 29, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/0163
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A copying method for producing duplicates of an original of at least two colors by using a composite photosensitive member including more than two photosensitive layers, wherein the photosensitive member is subjected to charging more than twice and exposed to an optical image of the original more than once by changing charging and exposing conditions, to vary charge carried on the surface and in the interior of the photosensitive member. This causes two types of electrostatic image to be formed on the surface of the photosensitive member; one type includes image regions having a positive surface potential, a negative surface potential and a substantially zero surface potential respectively and the other type includes two image regions having different surface potentials of same polarity respectively, and one image regions of substantially zero surface potential, depending on differences in color between image regions of the original corresponding to the image regions on the photosensitive member. By suitably selecting charging and exposing conditions, it is possible to selectively carry out, by using a single copying apparatus, a copying mode in which duplicates are produced in sev…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.