Focus error detecting device
US5453962A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 19, 1993 |
| Grant date | Sep 26, 1995 |
| Priority date | — |
| Expiry date | Aug 19, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0909
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A focus error detecting device includes a reflected beam splitter and at least two two-division photodetectors. The reflected beam splitter includes a diffraction grating part and a non-diffraction grating part separated by a line dividing a reflected beam. The dividing line projects to a line orthogonal to a guide groove on the information recording medium. The diffraction grating part produces a first split beam, and non-diffraction grating part produces a second split beam. Each two-division photodetector receives one of the first and second split beams incident and their light receiving sections, and produces a signal for effecting focus control.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.