Focus control apparatus and method for use with a video camera or the like
US6362852B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 22, 1997 |
| Grant date | Mar 26, 2002 |
| Priority date | — |
| Expiry date | Dec 22, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/673
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A focus control technique for use in a video camera or the like. An image of an object passes through a focus lens and an electric signal corresponding thereto is formed. High frequency components are extracted from the electric signals to generate estimation values indicative of focus states. A plurality of estimation values that are changed as the focus lens moves are stored in a storage device. A plurality of the stored estimation values are selected and along with the lens positions corresponding to the selected estimation values are used to calculate the just focus position. As a result, even if the estimation value includes noise or the estimation value constantly includes noise when the luminance is low, focus control may be performed with high accuracy. Furthermore, even if the focus lens is passed by the just focus position only once, it is possible to calculate the just focus position. Therefore, the just focus position may be determined at a high speed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.