Nested loop video disc servo system
US4247866A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 1979 |
| Grant date | Jan 27, 1981 |
| Priority date | — |
| Expiry date | Sep 11, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/85
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An active filter separates the function of a principal feedback loop which provides velocity error correction from that of a nested feedback loop which provides video signal frequency correction. A further feedback loop responsive to the active filter output signal and normally open under steady-state conditions, is closed under transient conditions for supplying a limited gain reducing signal to the input of the active filter whereby transient disturbance of the primary and nested loops is minimized with no loss of loop gain under steady-state conditions. The third loop includes a dead zone amplifier for distinguishing between transient and steady-state conditions and a limiter for limiting the gain reducing signal to a level below that which otherwise would tend to drive the active filter into a non-linear slow recovery condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.