Varied intensity and/or infrared auxiliary illumination of surveillance area
US5973730A · kind A · utility
12Cited by
12References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 26, 1997 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Aug 26, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Infrared radiation from a light source such as a laser diode illuminates the field of view of a surveillance camera. The amount of illumination is varied in intervals, which may for example, be about 3/4 of a second, by varying the power applied to the light source. The radiation may emanate from optical fibers surrounding a camera lens, or through other ports. The power to the laser diode may be altered in response to background light sensed by a photo cell. A filter on the camera preferentially passes reflected illumination of the source while alternating background illumination.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.