Automatic light control system
US4618254A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1982 |
| Grant date | Oct 21, 1986 |
| Priority date | — |
| Expiry date | Oct 15, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B20/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A system is disclosed for automatically controlling the light intensity of a light source as a function of the amount of light received by a photosensor. In a preferred embodiment the light source illuminates a reference background which, in turn, reflects the light incident thereon to a photosensor in a video camera. In response to this reflected light, the photosensor produces a video signal which is proportional to the amount of light reflected thereon. A first processor is responsive to the reception of the video signal over a preselected period of time and provides a first signal which is proportional to the amount of reflected light received by the photosensor over that preselected period of time. A second processor is responsive to the first signal and generater a control signal to automatically cause an adjustable power supply to change the voltage applied to the light source as a function of the amplitude of the control signal. The second processor is also controlled by a sensor signal initiated by the presence of the object to be copied.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.