Apparatus for detecting the focus condition of an imaging lens
US4500189A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 29, 1983 |
| Grant date | Feb 19, 1985 |
| Priority date | — |
| Expiry date | Sep 29, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/34
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An apparatus for detecting a focus condition of an imaging lens of a still camera by detecting a lateral shift of two images formed on a light receiving element array by means of light fluxes transmitted through different sections of the exit pupil of the imaging lens divided by a stripe mask is disclosed. The variation of outputs from light receiving elements of the array due to an image height is corrected electrically by means of a correction circuit including first and second triangular wave generating circuits for generating first and second triangular waves having negative and positive inclinations, a clock pulse generator for producing clock pulses, a signal selection circuit for selecting alternately the first and second triangular waves in synchronism with the clock pulses to produce a correction signal, and a multiplying circuit for multiplying the outputs from the light receiving elements with the correction signal to provide a corrected signal from which the lateral shift can be detected accurately.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.