Focus detecting apparatus utilizing reflecting surface having variable reflectivity or transmissivity
US4862442A · kind A · utility
19Cited by
2References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1988 |
| Grant date | Aug 29, 1989 |
| Priority date | — |
| Expiry date | Apr 15, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/0919
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A light beam emitted from a source is focused on an object. The beam reflected by the object passes through an optical member and is detected by a photodetector. The optical member has a reflecting surface the reflectivity of which varies continuously with respect to the angle of incidence.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.