Movement sensor for motor vehicle alarm system - has magnetic detector which only operates if sensor is subjected to sufficient level of shock or tilt

摘要

The sensor housing consists of an inner cylindrical tube (3) with integral base (4) and an outer cover (2) which has a fixing flange (5). A multiturn coil (7) is wound around the outside of the cylinder and connected (8) to an electronic signal detector (9). A signal is induced in the coil if a magnetic ball (1) inside the cylinder changes its position e.g. if the vehicle is tilted or subjected to a shock. The Ball normally rests in a small depression (12) in the base and will only move if the shock or tilt exceeds a pre-determined level.