Laser power-drive circuit having a scaling DAC supplying a scaled reference signal to a plurality of scaled DAC's that supply a plurality of scaled output signals
US5640381A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1996 |
| Grant date | Jun 17, 1997 |
| Priority date | — |
| Expiry date | Mar 8, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/182
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical disk recorder employs laser drive signals having diverse current or power levels. A scaling digital-analog-converter (DAC) supplies a scaled reference signal to a plurality of scaled DACs. The scaled DACs supply the diverse laser drive signals. Calibrating the scaling DAC calibrates the scaled DACs. A base array of DACs include not only the scaling DAC but a plurality of base array DACs. Such base array DACs control reading operations as well as supplying a threshold current. The threshold current is that laser drive signal current level below which laser 25 does not emit a laser beam. During writing, the CUT current is added to the laser drive currents supplied by the scaled DACs. A desired CUT current is determined by calculating a slope of the laser drive current to emission of radiation. Then the slope is extrapolated to a zero emission point below which no coherent emission of radiation occurs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.