Lens and aperture control apparatus
US5194956A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 17, 1990 |
| Grant date | Mar 16, 1993 |
| Priority date | — |
| Expiry date | Oct 17, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/75
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Lens control apparatus for use in a video camera in which an object is imaged through an adjustable lens onto an image pick-up element from which a video signal is derived. The lens is driven for focus or zoom adjustments by servo control at a rate determined by the synchronizing signal included in the video signal. The aperture of the video camera also is controlled by detecting the amount of light which impinges on the image pickup element and then determining the ratio between the detected light level and a reference level representing the brightness of the object. The aperture is driven (i.e. it is enlarged or reduced) as a function of the product of the aforementioned ration and a coefficient which changes with the aperture opening. When the aforementioned ratio is less than unity, the coefficient increases as the aperture opening decreases and, conversely, decreases as the opening increases. When the ratio is greater than unity, the coefficient increases as the aperture opening increases and, conversely, decreases as the opening decreases.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.