| 摘要 |
<p>Detectors (10) are distributed like small mines around flower beds and lawns, around the outside of a house - in the manner of a minefield - so that any prowler such as a burglar is liable to tread on a detector (10), setting off an alarm, before he has the chance to break into and enter the house. The detectors (10) may be independently operative, or may be interconnected by cables in an alarm system. Each detector (10) is a weather-proof detector adapted for use outdoors for detecting a prowler, and comprises a body (12), the outside of which is formed by a housing (18), on the top of which is a nipple (22). The detector (10) is adapted to be buried in the ground, just below the surface, and has a pressure-sensitive device (16) in the body (12), responsive when in use to the prowler's stepping on the buried detector (10) to cause operation of an alarm or to cause transmission of an alarm signal.</p> |
