PIR motion sensor utilizing sum and difference sensor signals
First Claim
Patent Images
1. A PIR motion sensor comprising:
- at least one infrared detector having at least first and second elements generating respective first and second signals; and
a system adding the first and second signals together to render a “
sum”
signal, the system also rendering a “
difference signal”
by subtracting one signal from the other signal, wherein the system outputs a detection signal representative of a moving object when the “
sum”
signal has a frequency different than that of the “
difference”
signal, and otherwise does not output the detection signal.
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Abstract
A passive infrared sensor has two detector elements, each of which has a positive part and a negative part, with each detector element generating respective first and second signals. The signals are added together to render a “sum” signal and are also subtracted one from the other to render a “difference” signal, and a moving object is indicated only when the “sum” signal has a frequency different than the frequency of the “difference” signal.
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Citations
12 Claims
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1. A PIR motion sensor comprising:
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at least one infrared detector having at least first and second elements generating respective first and second signals; and a system adding the first and second signals together to render a “
sum”
signal, the system also rendering a “
difference signal”
by subtracting one signal from the other signal, wherein the system outputs a detection signal representative of a moving object when the “
sum”
signal has a frequency different than that of the “
difference”
signal, and otherwise does not output the detection signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method for discriminating a moving object in a monitored space from a non-moving object characterized by non-constant radiation, comprising:
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providing first and second detector elements generating respective first and second signals; adding the signals together to render a “
sum”
signal;subtracting one signal from the other to render a “
difference”
signal; andindicating a moving object if the “
sum”
signal has a frequency that is different from the frequency of the “
difference”
signal, and otherwise not indicating a moving object. - View Dependent Claims (7)
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8. A motion sensor, comprising:
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at least a first passive IR detector element having two and only two parts and monitoring a first subvolume of space; at least a second passive IR detector element having two and only two parts and monitoring a second subvolume of space; an optics system at least partially optically interposing and/or superposing the first and second subvolumes; and a system indicating a moving object only if a frequency of the difference between signals generated by the elements is different from a frequency of the sum of the signals generated by the elements. - View Dependent Claims (9, 10, 11, 12)
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Specification