Focus detecting system
US4341953A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 1980 |
| Grant date | Jul 27, 1982 |
| Priority date | — |
| Expiry date | May 19, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B3/10
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focus detecting system for detecting focusing condition of an image forming optical system to an object. In this system there are produced first and second signals corresponding to imaging conditions of object images at first and second positions on front and rear sides of and at substantially equal distances from a predetermined focal plane of said optical system, respectively, and another signal corresponding to imaging condition of an object image at third position substantially coincident with said predetermined focal plane. In accordance with these first, second and third signals, a decision is given as to the focusing condition, namely, in-focus, near-focus or far-focus condition, as well as, the distinction between correctly focused condition and considerably defocused condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.