Information recording and/or reproducing apparatus and method for adjusting an offset amount of a focusing servo circuit
US5559772A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 14, 1994 |
| Grant date | Sep 24, 1996 |
| Priority date | — |
| Expiry date | Feb 14, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0941
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An information recording and/or reproducing apparatus has an auto gain controller for controlling the amplitude level of a reproduction signal read out from a recording medium to a predetermined level. The auto gain controller has a variable gain amplifier for amplifying the reproduction signal, a converter for converting the output of the variable gain amplifier into a DC voltage, and a comparator for comparing the output from the converter with a predetermined reference value and sending the result of the comparison to the variable gain amplifier. The controller also includes a fixing device for fixing the gain of the variable gain amplifier, and a focusing offset for applying an adjuster offset to a focusing servo loop when the gain is fixed by the fixing device, and introducing the output of the converter thereinto while varying the amount of the applied offset, thereby effecting the adjustment of the focusing offset.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.