Intrusion detection systems employing automatic sensitivity adjustments
US4064509A · kind A · utility
13Cited by
5References
11Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jul 19, 1976 |
| Grant date | Dec 20, 1977 |
| Priority date | — |
| Expiry date | Jul 19, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/04
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An automatic test circuit for a photo electric intrusion system incorporates an electronic attenuator which serves to reduce the sensitivity of the receiver when a light beam does not impinge on a photocell located at the receiver. As soon as the light beam appears on the photocell, the sensitivity of the receiver is increased to a normal operating value. In this manner, if the beam were misaligned to cause less light to impinge on the photocell, the receiver would indicate an alarm condition to thereby inform a user of the problem.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.