Patent ID: 6642846
Filing Date: 2003-11-04
Classification: G08B

Abstract:
An intrusion detector for detecting an intrusion into a protected space overlying a predetermined surface, comprising:a housing to be mounted over said surface and including an infrared radiation sensor for sensing moving infrared radiation sources, and a transparent window thereover; a plurality of lens elements formed in said transparent window each oriented to receive infrared radiation from a moving infrared radiation source within a predetermined viewing zone of said protected space and to transmit infrared radiation from said source to said sensor; an alarm; and a control system for receiving the electrical output of said sensor and for outputting an alarm signal to said alarm when a moving infrared radiation source is simultaneously detected within at least two of said predetermined viewing zones, wherein said lens elements are oriented such that their viewing zones define a plurality of viewing planes at different inclinations with respect to said surface, with the viewing zones in the viewing planes of smallest inclinations detecting moving infrared radiation sources most distant from the sensor, and wherein each of the lens elements produces approximately the same magnitude of electrical output from said sensor irrespective of the distance of the moving infrared radiation source from the sensor.