Optical transducer and focusing system
US4152586A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 1978 |
| Grant date | May 1, 1979 |
| Priority date | — |
| Expiry date | May 26, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0912
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical transducer having concentric radiant beam detectors for converting a radiant beam to electrical signals including a first axially placed detector with a second detector concentric therewith. In one embodiment, the detectors receive the radiant beam through an amplifying auxiliary lens. Changes in focus differentially affect the magnitude of the beam impinging on the individual detectors, resulting in corresponding changes in the individual detector outputs. A focusing system employing the transducer moves a focusing lens in response to the differential output of the individual detectors. The focusing system can be employed in a video disc reading system so that the video disc scanning beam is always focused precisely at the disc. An electrical difference circuit leading from the photo-detectors generates a driving signal to energize a lens-moving motor for shifting the focusing lens along the axis of the beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.