Detector for alarm system
US4075616A · kind A · utility
Inventor
Key dates
| Filing date | Nov 12, 1975 |
| Grant date | Feb 21, 1978 |
| Priority date | — |
| Expiry date | Nov 12, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H3/142
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Sensing devices responsive to changes in the physical condition of the area in which they are located are disposed in elongate, flexible carriers to form a detecting unit which can be arranged in a tortuous, undulating array to cover an undefined area of any shape desired with a detecting density of any chosen value. The detecting unit can assume various forms including that of a pair of conducting elements disposed within an insulating tube in opposed relation positioned to complete the continuity of a switching circuit when the tube is flexed to cause engagement of the conductors. Another embodiment comprises a plurality of braided strands of insulating material extending lengthwise within an insulating carrier cable sheath. A pair of conductors is included in the braiding in a spiral disposition with each conductor being disposed along the entire length in opposed relation to the other conductor. Another embodiment includes a closed tubular element filled with an inelastic fluid having a servomechanism at one end to actuate a switching device for an electric alarm circuit in response to a change in liquid level. A modification of this embodiment would include a light responsive …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.