PIR MOTION SENSOR

• US 20080074252A1
• Filed: 09/11/2007
• Published: 03/27/2008
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Suren Systems, Ltd.
• Original Assignee: Suren Systems, Ltd.
• Inventors: Micko, Eric
• Granted Patent: US 7,579,595 B2
• Time in Patent Office: Days
• US Class Current: 340/521
• CPC Class Codes: G08B 13/191 using pyroelectric sensor means

Abstract

A passive infrared sensor has two or more element arrays, each consisting of positive polarity and negative polarity elements. The signals from the arrays are both summed together and subtracted from each other, and if either the sum or difference signal exceeds a threshold, detection is indicated.

Claims

1. A PIR motion sensor comprising:

at least a first array of pyroelectric elements;

at least a second array of pyroelectric elements; and

at least one processor receiving respective first and second signals representative of the outputs of the first and second arrays, the processor adding the first and second signals together to establish a sum signal and subtracting the first signal from the second signal to establish a difference signal, the processor determining, for each of the sum signal and the difference signal, whether detection should be indicated, wherein the sensor is mounted on a ceiling.

2. The sensor of claim 1, wherein the difference signal in generated by reversing the polarity of the first signal and then adding the first signal with polarity reversed to the second signal.

3. The sensor of claim 1, wherein each array includes at least four elements, two with positive polarity and two with negative polarity.

4. The sensor of claim 3, wherein each element in the first array is azimuthally straddled by elements of the second array.

5. The sensor of claim 3, wherein the elements of each array are electrically connected to each other in the following azimuthal order with respect to polarity:

positive to negative to positive to negative.

6-7. -7. (canceled)

8. A passive infrared sensor having two or more element arrays, each array consisting of positive polarity elements and negative polarity elements, signals from the arrays being both summed together and subtracted from each other for each of at least some detection cycles, detection and/or motion being indicated if either the sum signal or the difference signal exceeds a threshold, wherein the sensor is mounted on a ceiling.

9. The sensor of claim 8, wherein the difference signal is generated by reversing the polarity of a first signal from a first array and then adding the first signal with polarity reversed to a second signal of a second array.

10. The sensor of claim 8, wherein each array includes at least four elements, two with positive polarity and two with negative polarity.

11. The sensor of claim 10, wherein each element in a first array is azimuthally straddled by elements of a second array.

13-14. -14. (canceled)

15. A computer readable medium executable by a processing system to undertake logic comprising:

receiving first signals from a first ceiling-mounted array of pyroelectric elements;

receiving second signals from a second ceiling-mounted array of pyroelectric elements;

adding the first signal to the second signal to establish a sum signal;

subtracting the first signal from the second signal to establish a difference signal;

only if neither the sum signal nor the difference signal meets a detection criteria, not indicating detection, and otherwise indicating detection.

16. The medium of claim 15, wherein the difference signal is generated by reversing the polarity of the first signal and then adding the first signal with polarity reversed to the second signal.