Floating disc photoconductive film reader
US4450489A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1981 |
| Grant date | May 22, 1984 |
| Priority date | — |
| Expiry date | Dec 28, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/21
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A photoconductive film reader comprises a disc with a read head attached to its bottom surface at an edge point and rotated over the photoconductive film at a sufficiently high velocity so that the read head floats aerodynamically on the film, the read head having means for sensing the information stored as electrostatic charge on the film. The film has a reset strip of a predetermined amount of charge prerecorded along one of its edges, resetting of the read head electronics being coincident with the passage of the read head over the reset strip. The floatation of the read head on the film reduces the effect of film modulations on the film-to-read head spacing and allows the spacing to be well defined and controllable.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.