Automatic gain control system and information reproduction apparatus using it
US5574709A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 20, 1994 |
| Grant date | Nov 12, 1996 |
| Priority date | — |
| Expiry date | Jul 20, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B11/10515
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An AGC system controls the amplitude of a reproduction signal read out from a recording medium at a predetermined level by adjusting the gain of an AGC amplifier. The AGC system includes a differentiator which differentiates the output signal of the AGC amplifier and then outputs a resultant differential signal. A rectifier rectifies the output differential signal. An operation unit compares the output signal of the rectifier with a predetermined reference value and outputs an error signal corresponding to the difference between them. The gain of the AGC amplifier is adjusted according to the error signal so that the output signal of the AGC amplifier and the output signal of the differentiator may be controlled at respective predetermined levels. The amplitude level of a reproduction signal can be maintained at a predetermined level regardless of the MTF characteristics of an optical system or other factors and a single AGC circuit can provide both reproduction signals which are suitable for both mark edge recording and mark position recording.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.