Flexible tube optical intrusion detector

摘要

A hollow flexible vinyl or other plastic tube having a shiny inner wall is disposed along a boundary where intrusion detection is desired. A beam of infrared radiation from an LED at one end of the tube is passed through the tube by reflections from the wall to a detector at the other end. The radiation is conducted along curved paths as well as straight paths. An object intruding into the protected space with sufficient force to deform the tube wall attenuates the radiation. A detection circuit senses the attenuation and produces an intrusion signal. The detection circuit includes logic which detects a failure in the radiation source or a light leak in the tube.