Focus detecting device
US3938894A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 1974 |
| Grant date | Feb 17, 1976 |
| Priority date | — |
| Expiry date | Dec 12, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/36
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A photoelectric focus detecting member includes a semiconductor substrate of a first polarity and at least two closely transversely spaced parallel longitudinally extending photosensitive laminae of a polarity opposite to the first polarity to form corresponding photodiodes. Each of the photosensitive laminae is masked to provide regularly spaced light receiving areas alternating with masked areas, the light receiving areas of successive transversely spaced photodiodes being relatively longitudinally offset to present a checkered pattern. The detecting element is positioned in the focal plane of a lens and is either stationary or oscillated. The difference in potential between the diodes or the amplitude of the AC current in a circuit including the photodiodes is a function of the condition of focus of the lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.