Patent ID: 7319228

Claim:
A passive infra-red detector comprising: at least three sub-detectors, each of said at least three sub-detectors being operative to receive infra-red radiation from a corresponding one of at least three sub fields-of-view, each of said at least three sub fields-of-view being exclusively defined by an optical element which does not define any other of said at least three sub fields of view, said at least three sub fields-of-view being angled with respect to each other; and reduced false alarm signal processing circuitry, receiving output signals from said at least three sub-detectors, noting at least one of time durations of said output signals of at least two adjacent ones of said at least three sub-detectors and time differences between receipt of said output signals from said at least two adjacent ones of said at least three sub-detectors, and providing a motion detection output, said reduced false alarm signal processing circuitry being operative to eliminate at least some false alarms at least based on at least one sensed time relationship among at least two of said at least one of time durations of said output signals and said time differences between receipt of said output signals.