Exposure control in electronic cameras by detecting overflow from active pixels
US6452633B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 26, 1998 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Feb 26, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/771
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for controlling the exposure of an active pixel array electronic still camera includes the steps of: integrating photocurrent in each pixel during an integration time period; collecting overflow charge from all pixels in the array during the integration time period; developing an overflow signal as a function of the overflow charge; and terminating the integration time period when the overflow signal exceeds a preset threshold level selected to represent a desired reference exposure level. Apparatus for performing the method of the present invention includes circuitry for integrating photocurrent in each pixel during a integration time period; circuitry for diverting and detecting overflow charge from all pixels in the array during the integration time period; circuitry for developing an overflow signal as a function of the overflow charge; and circuitry for terminating said integration time period when the overflow signal exceeds a preset threshold level selected to represent a desired reference exposure level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.