Control system for detecting intrusion of a light curtain
US5404008A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 16, 1993 |
| Grant date | Apr 4, 1995 |
| Priority date | — |
| Expiry date | Jul 16, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V8/20
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A light curtain system having a series of light emitting diodes is arranged to produce a beam of light which is modulated at about 40 KHz. The light is broadcast across a physical space in which intrusion detection is desired and received by respectively arranged photo diodes. Each of the light emitting diodes is connected in parallel to a single modulated power supply. Each photo diode produces an electrical signal having a magnitude which is proportional to the amount of light incident thereon. The signal produced by each photo diode is sequentially sampled and then compared to a reference value. If an intrusion in the respective region of the light curtain has occurred, the magnitude of the sampled signal will be less than the reference value providing indicia of an intrusion. Upon such a detection, the light curtain system provides indicia of the intrusion such that consequential remedial action in response thereto may be performed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.