Light power control circuit for a semiconductor light-emitting element
US5059780A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1990 |
| Grant date | Oct 22, 1991 |
| Priority date | — |
| Expiry date | Jun 19, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/06835
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A light power control circuit by which a stable writing without any influence of a high-frequency current on writing data is enabled by performing superposition of the high-frequency signal on a drive current of a laser diode only during a reading mode, and by inhibiting the superposition of the high-frequency current during a writing mode. In a further embodiment having a construction in which a writing drive current is superposed on a reading drive signal in the form of pulses and a voltage proportional to a writing power is subtracted from an error signal in a servo system, an influences of a writing data component on the operation of the servo system is eliminated by effecting a level shift to the voltage by a predetermined level and subtracting the voltage after the level shift from the error signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.