Passive remote photoelectric surveillance alarm with telescopic optics
US5047749A · kind A · utility
1Cited by
3References
14Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Apr 3, 1990 |
| Grant date | Sep 10, 1991 |
| Priority date | — |
| Expiry date | Apr 3, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/1895
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An intruder alarm includes a circuit with a photoresistive cell located in a housing with a piezoelectric crystal sound generator and battery to power the circuit and sound generator. A telescope concentrates light from a distance in a limited field of view upon the photoresistive cell to trigger the piezoelectric crystal sound generator when light intensity on the cell changes sufficiently from an ambient light intensity level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.