Focus detecting device for a camera
US4618235A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 1985 |
| Grant date | Oct 21, 1986 |
| Priority date | — |
| Expiry date | Jul 12, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/34
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A focus detecting device includes an image sensor such as a CCD which converts the intensity of the light indicent thereon into the amount of a charge, integrates or accumulates the charge, terminates the integration operation when the level of the integrated charge reaches a given value or when a given integration limit time has lapsed, and outputs the integrated charge as an image signal which in turn is amplified step-by-step in accordance with the brightness of the object for the focus condition detection. Two different integration limit times are provided such that the integration operation is terminated at the shorter time while the focus detection is possible within the shorter time. The integration operation is terminated at the longer integration limit time when the focus detection is impossible with the shorter time and with the image signal given by the integration for the shorter time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.