Drive circuit for semiconductor laser of opto-electric recording/playback apparatus
US4754460A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 20, 1987 |
| Grant date | Jun 28, 1988 |
| Priority date | — |
| Expiry date | Jan 20, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B19/04
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A drive circuit for a semiconductor laser in an apparatus for recording/playback of data utilizing an optical recording medium includes circuit elements for establishing recording and playback operating conditions respectively in which output light levels from the laser are set to suitable values for recording and playback, and for controlling the laser output light levels during recording and playback operation at fixed values, and moreover for modulating the laser output light in accordance with a recording signal during recording operation. A changeover control signal which executes changeover between the recording and playback conditions is derived such as to begin in coincidence with the start of a leading pulse of a series of recording signal pulses, and to end immediately following the final recording signal pulse, to thereby avoid excessive laser drive current levels following changeover between playback and recording operating conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.