Automatic focus control device
US5182649A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 6, 1991 |
| Grant date | Jan 26, 1993 |
| Priority date | — |
| Expiry date | May 6, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/959
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An automatic focus control device capable of obtaining an accurate in-focus state of a subject having less high-frequency components is provided. A luminance signal of the video signal of the subject is first differentiated by a combination of a delay circuit (27) and a difference forming circuit (26). The differentiated luminance signals are accumulated by an accumulator (31), and a clock pulses CL are counted by a counter (32) during the periods when the differentiated luminance signals exceed a predetermined value. The accumulated value is then divided by the clock count at a divider (33) to obain a focus control signal which is fed to a microcomputer (35). The microcomputer causes a lens (11) to move in accordance with this focus control signal so that an optimum in-focus state of the subject is obtained.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.