Apparatus and method for setting a threshold level to maintain duty cycle in a pulse width modulated optical recording system
US5396479A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 6, 1994 |
| Grant date | Mar 7, 1995 |
| Priority date | — |
| Expiry date | May 6, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/10009
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An apparatus for setting a threshold voltage for determining bit positions of digital data stored on an optical recording device utilizing pulse width modulation. The optical recording device reads a pattern from an optical medium. The read pattern has a fixed, known duty cycle. A feedback circuit processes the pattern according to an initial threshold voltage. The feedback signal is then input to a comparator. The comparator compares the feedback signal against the pattern. Based on this comparison, the amount of current input to and output from a compensation circuit is adjusted. Thereupon, the compensation circuit sets the threshold voltage accordingly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.