Semiconductor laser driving circuit with control circuit power voltage monitor for preventing inadvertent recording
US5170389A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 15, 1990 |
| Grant date | Dec 8, 1992 |
| Priority date | — |
| Expiry date | Jun 15, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/06825
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The invention provides an improvement of the conventional laser driving circuit mainly including a control logic circuit, a reproducing power producing circuit, and a recording power producing circuit for preventing a recording film of a disk from being damaged by a laser in a reproducing mode. The improved respect is addition of a voltage monitoring circuit and a bypass transistor for an abnormal signal. The voltage monitoring circuit monitors a voltage drop caused in the control logic circuit and supplies a voltage abnormality indicating signal, thereby causing the bypass transistor to be conductive for allowing the abnormal signal to be flown therethrough.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.