Passive infrared intrusion detector

摘要

A passive infrared intrusion detector is provided of the type having an infrared sensor for detecting a change in temperature in the field of view of the sensor caused by an intruder moving therein, optical means for focusing radiation from the field of view on the sensor, and an alarm which is activated when the sensor detects a change in temperature. The improvements reside in mounting the passive intrusion detector in a generally C-shaped housing exposed to a field of view which may be shifted through an angle of at least 180 DEG . A bendable, translucent window is provided having slots in opposite ends thereof which engage projections on opposite sides of the housing. The window is very simply released by applying thumb pressure to the window in the proximity of the projections. The intrusion detector is also provided with a horn-like enclosure which surrounds the sensor. A flexible Fresnel lens may be rapidly mounted on the enclosure, permitting ready adaptation of the detector to local conditions. Incorporated in the detector are a light source and movable mirror. The light source is mounted at a conjugate point with respect to the sensor so that the light source may be projected on the same field of view as that seen by the detector. This permits the detector to be easily and rapidly aimed.