Focusing system for videodisc player
US3997715A · kind A · utility
58Cited by
6References
15Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Mar 25, 1974 |
| Grant date | Dec 14, 1976 |
| Priority date | — |
| Expiry date | Mar 25, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0912
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A focus detector includes apertured photodetectors which intercept a radiant beam. Changes in focus differentially affect the amount of radiation impinging on the detectors resulting in corresponding changes in their signal output. A videodisc system employing the detector moves a focusing lens to compensate for variations in the position of a target videodisc, so that a scanning beam is always accurately transmitted to a detector. A difference circuit connected to two photodetectors generates a driving signal to energize a lens-moving motor for shifting the focusing lens toward or away from the videodisc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.