Focus detection method involving cutting more than half of light beam reflected from disc
US4684799A · kind A · utility
10Cited by
5References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1986 |
| Grant date | Aug 4, 1987 |
| Priority date | — |
| Expiry date | Jun 30, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B7/0916
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A knife edge type focus detection method for optics associated with an optical pickup is disclosed. A light intercepting member is interposed between an object lens and a light receiving element for focus detection in order to cut 60-95% of a reflected flux for focus detection before the flux reaches the light receiving element. The intercepted part of the flux includes a light ray which propagates through the optical axis of the optics.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.