Passive infra-red detectors
First Claim
1. A passive infra-red detector comprising:
- at least two sub-detectors, each operative to receive infra-red radiation from a corresponding one of at least two sub fields-of-view; and
signal processing circuitry, receiving output signals from said at least two sub-detectors and noting time relationships of said output signals from said at least two sub-detectors and providing a motion detection output in response to receipt of said output signals from said at least two sub-detectors, representing traversal of said at least two sub fields-of-view, having a time relationship which meets at least one predetermined criterion,at least one of said at least one predetermined criterion being traversal of said at least two sub fields-of-view in a first direction at least a predetermined time following traversal of said at least two sub fields-of-view in a second direction, generally opposite to said first direction.
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Accused Products
Abstract
A passive infra-red detector including at least three sub-detectors, each sub-detector being operative to receive infra-red radiation from a corresponding one of at least three sub fields-of-view, each sub field-of-view being exclusively defined by an optical element which does not define any other sub field of view, the sub fields-of-view being angled with respect to each other, adjacent ones of the sub fields-of-view being separated by a gap of no more than 30 degrees and at least one of the sub fields-of-view having at least one of the following characteristics: extending over no more then 45 degrees in azimuth; and including not more than three azimuthally distributed detection zones, and signal processing circuitry, operative to receive output signals from the sub detectors and to provide a motion detection output.
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Citations
4 Claims
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1. A passive infra-red detector comprising:
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at least two sub-detectors, each operative to receive infra-red radiation from a corresponding one of at least two sub fields-of-view; and signal processing circuitry, receiving output signals from said at least two sub-detectors and noting time relationships of said output signals from said at least two sub-detectors and providing a motion detection output in response to receipt of said output signals from said at least two sub-detectors, representing traversal of said at least two sub fields-of-view, having a time relationship which meets at least one predetermined criterion, at least one of said at least one predetermined criterion being traversal of said at least two sub fields-of-view in a first direction at least a predetermined time following traversal of said at least two sub fields-of-view in a second direction, generally opposite to said first direction. - View Dependent Claims (2, 3, 4)
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Specification