Focus error detecting device
US5532987A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1995 |
| Grant date | Jul 2, 1996 |
| Priority date | — |
| Expiry date | Apr 26, 2015 |
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 obscurer and a two-division photodetector. The observer obscures a part of the reflected beam. The two-division photodetector includes first and second light receiving sections separated from each other by a division band region which receive the reflected light beam not obscured by the obscurer. A focus error signal is produced based on the output of each light receiving section. Each light receiving section has an array of tapered projections along its edge in the division band region. Alteratively, the light receiving sections have a main part with an edge coincident with an edge of the division band region, and groups of light receiving stripes extending in a direction parallel with the edges of the main part.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.