Periodically biased video disc player servo system
US4286282A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 20, 1979 |
| Grant date | Aug 25, 1981 |
| Priority date | — |
| Expiry date | Aug 20, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B9/06
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Periodic biasing of video disc player signal correction servo to the center of its control range avoids the loss-of-loop gain which otherwise could occur if the servo were continuously biased and minimizes loop stabilization time. Periodic biasing is provided by means of a timing circuit, responsive to a luminance signal transition above blanking level, which enables the servo phase error detector and simultaneously enables a precharging circuit which charges the servo error voltage holding capacitor to a level corresponding to a zero error servo condition. The timing circuit disables the precharging circuit a predetermined time subsequent to an opposite transition of the luminance signal and disables the phase detector subsequent to disabling of the precharging circuit. The period between disabling of the precharging circuit and disabling of the phase detector encompasses the color burst interval of the horizontal sync pulse and may be controlled by selection of offset and slope parameters of an integrator in the timing circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.