Nondestructive readout of a latent electrostatic image formed on an insulating material
US4873436A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 4, 1987 |
| Grant date | Oct 10, 1989 |
| Priority date | — |
| Expiry date | May 4, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/221
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method and apparatus are described for the nondestructive readout of a latent electrostatic image formed on a sheet or layer of insulating material. A sheet or layer of semiconductor material is disposed in relatively close proximity to the insulating material. A latent electrostatic image formed on the insulating material (by any known means) causes a surface depletion layer to be produced by induction at the surface of the semiconductor material. The location and distribution of the accumulated charges on the semiconductor material are read out as analog electrical signals corresponding to the AC surface photovoltage induced on the semiconductor material as the semiconductor material is scanned with a low intensity modulated light beam of appropriate wavelength, the magnitude of the analog signals depending on the local charge density. The analog electrical signals so obtained are then digitized, processed and stored and/or displayed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.