Automatic focusing device
US4465352A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 16, 1982 |
| Grant date | Aug 14, 1984 |
| Priority date | — |
| Expiry date | Sep 16, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/38
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An automatic focusing device for moving a photographic lens to an optimum focusing position by detecting an object image contrast signal that changes with the varying position of the photographic lens. The device stops the photographic lens while it is being moved between an infinite distance photographing position to a least distance photographing position when the level of the detected contrast signal becomes less than a threshold level. The invention compares a first signal, which is set to correspond to a position at which the photographic lens is to be stopped, and a second signal, which is generated when the contrast signal level is less than the preset threshold level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.