System which uses threshold counts to achieve automatic focus
US4843413A · kind A · utility
3Cited by
26References
7Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jun 28, 1988 |
| Grant date | Jun 27, 1989 |
| Priority date | — |
| Expiry date | Jun 28, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/36
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Apparatus for generating automatic focus signals for positioning a lens includes a circuit for calculating a difference value between a selected pixel intensity level and the average value of the pixel intensities which neighbor the selected pixel. The difference value is fed to a thresholding circuit which generates a signal for clocking a downstream counter whenever the difference value exceeds a selected threshold value. The lens is repositioned until the output from the counter is a maximum thereby indicating an infocus position of the lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.