Alarm device for car, has detection unit to detect variation of distance between body shell of vehicle and ground, and alarm unit that is automatically activated when variation exceeds certain threshold value

摘要

The device has a measurement unit comprising a photoelectric cell, which utilizes triangulation principle to periodically measure a distance between body shell of the vehicle and the ground. A detection unit detects a variation of the distance after vehicle is stopped. An alarm unit is automatically activated when the variation exceeds a certain threshold value.