Magnetic imaging for photocopying
US4122455A · kind A · utility
Inventor
Key dates
| Filing date | Jan 24, 1977 |
| Grant date | Oct 24, 1978 |
| Priority date | — |
| Expiry date | Jan 24, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G19/00
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A magnetizable layer is initially magnetized and selected portions thereof are demagnetized by an optical imaging system. In one embodiment, an image to be reproduced is projected through a transparent electrically conductive electrode which is brought into contact with a photoconductive matrix through which is dispersed magnetizable particles. Changes in resistivity of the photoconductive matrix causes a current density distribution, which corresponds to the image intensity distribution, to flow transversely from the transparent electrode through the photoconductive matrix to a support electrode on which the matrix is fixed when a potential is applied between the transparent and support electrodes. The current distribution results in corresponding magnetic fields which modify or "erase" selected portions of the initially magnetized layer. In another embodiment, the photoconductive layer is adjacent to the magnetic layer and is disposed between two spaced electrodes arranged in a plane substantially parallel to the magnetic layer. In each case, subsequent to selected erasure, magnetic ink is applied to the remaining magnetized portions for subsequent transfer to a desired surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.