Optical pickup apparatus and optical recording medium drive employing the same including a first photo receiving element for detecting the state of light beam and a second photo receiving element for reproducing information
US6212150A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1998 |
| Grant date | Apr 3, 2001 |
| Priority date | — |
| Expiry date | Feb 23, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0909
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
First and second photodiodes are arranged on the upper surface of a stem, returned light beams diffracted in the + 1st order by a transmission type holographic optical element are received by the first photodiode, while returned light beams diffracted in the - 1st order are received by the second photodiode. The first photodiode has a plurality of light receiving regions, and respectively outputs a reproducing signal, a focus error signal and a tracking error signal on the basis of the returned light beams. On the other hand, the second photodiode has a single light receiving region, and outputs a reproducing signal on the basis of the returned light beams.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.