Laser power monitor device, optical pickup including the same, and optical recording and/or reproducing apparatus including the same
US7272103B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 2004 |
| Grant date | Sep 18, 2007 |
| Priority date | — |
| Expiry date | Jun 26, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/1263
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In order to improve the frequency characteristic of a laser power monitor device and the precision of laser power control when low-speed recording is performed, there is provided a laser power monitor device for an optical recording and/or reproducing apparatus, the laser power monitor device including a photo diode unit to receive part of a light emitted from a laser diode and output a current proportional to optical power, and a monitor circuit to receive the current output from the photo diode unit, convert the received current into a voltage, and outputs the voltage to an automatic laser power control circuit, and the photo diode unit includes a plurality of photo diodes connected to the monitor circuit to supply current to the monitor circuit. The laser power monitor device further includes a switch unit, wherein the switch unit is located between the photo diode unit and the monitor circuit to receive a signal on a current recording speed and switch so that the number of photo diodes supplying current to the monitor circuit is reduced as the recording speed is increased.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.