Alarm apparatus for detecting disturbance or other change of condition
US4253095A · kind A · utility
9Cited by
13References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1978 |
| Grant date | Feb 24, 1981 |
| Priority date | — |
| Expiry date | Jun 7, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/08
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A compact portable housing encloses a piezoelectric element which receives short pulses from a pulse generator circuit controlled by a ramping waveform generator circuit so that the element and the adjacent speaker portion of the housing produce a frequency modulated loud sweeping sound. The housing also encloses a detector switch for sensing a disturbance, and the sensitivity of the switch may be adjusted according to the position of the housing. The detector switch actuates a timer circuit which is armed or disarmed by moving a combination code switch having code wheels projecting from the housing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.