Heat source detector

• US 5,565,683 A
• Filed: 12/05/1994
• Issued: 10/15/1996
• Est. Priority Date: 12/03/1993
• Status: Expired due to Term

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Ando, Masaaki
• Primary Examiner(s): Fields, Carolyn E.
• Assistant Examiner(s): Glick, Edward J.
• Application Number:
  US08/349,721
• Time in Patent Office: 680 Days
• Field of Search: 250/338.3, 250/342, 250/330, 250/332, 250/334, 250/DIG. 1, 250/349
• US Class Current: 250/342
• CPC Class Codes: G01J 2005/0077 Imaging
• CPC Class Codes: G01S 3/784 using a mosaic of detectors
• CPC Class Codes: Y10S 250/01 Passive intrusion detectors

Abstract

A heat source detector includes an infrared sensor 1 wherein plural infrared ray sensing elements 7 on which an infrared image is formed by an infrared lens 10 are arranged into an array form; and an infrared analyzer 2 which analyzes a detection signal detected by the infrared ray sensing elements 7. The infrared analyzer 2 has: an infrared intensity detecting unit 3 which detects the infrared intensity for each of the infrared ray sensing elements 7; an infrared center of gravity detecting unit 5 which obtains the center of gravity of a heat source emitting infrared rays, from the infrared intensities detected by the infrared intensity detecting unit 3, and a heat source moving direction detecting unit 6 which obtains the moving direction of the heat source, from temporal vector displacement of the center of gravity obtained by the infrared center of gravity detecting unit 5.

Claims

1. A heat source detector, comprising:

an infrared sensor having a plurality of infrared ray sensing elements; and

an infrared analyzer for analyzing a detection signal detected by said infrared ray sensing elements, said infrared analyzer including an intensity detecting unit for detecting an intensity for each of said infrared ray sensing elements, and a center of gravity detecting unit for detecting the center of gravity of a heat source emitting the infrared rays from the intensities detected by said intensity detecting unit.

2. A heat source detector according to claim 1, wherein said infrared analyzer further comprises a heat source moving direction detecting unit for detecting a temporal vector displacement of the center of gravity detected by said center of gravity detecting unit to detect a moving direction of the heat source.

3. A heat source detector according to claim 1, wherein said plurality of infrared ray sensing elements are arranged into an array form in x- and y- directions.

4. A heat source detector according to claim 1, wherein said infrared analyzer further comprises a heat source position extracting unit which receives the intensity for each of said infrared ray sensing elements from said intensity detecting unit to extract said infrared ray sensing elements which have a predetermined intensity level or more, and said center of gravity detecting unit detects the center of gravity of the heat source according to the intensities of said infrared ray sensing elements extracted by said heat source position extracting unit.

5. A heat source detector according to claim 1, further comprising a chopper provided in front of said infrared sensor, said chopper being slidably movable for allowing the infrared rays to enter the infrared sensing elements without obstruction and to prevent the infrared rays from entering the infrared sensing elements.

6. A heat source detector according to claim 1, wherein said analyzer receives the infrared intensity for each of said infrared ray sensing elements at regular time intervals.

7. A heat source detector according to claim 1, wherein said infrared ray sensing elements are pyroelectric infrared sensors.

8. A heat source detector according to claim 2, wherein said infrared ray sensing elements are pyroelectric infrared sensors.

9. A heat source detector according to claim 3, wherein said infrared ray sensing elements are pyroelectric infrared sensors.

10. A heat source detector according to claim 4, wherein said infrared ray sensing elements are pyroelectric infrared sensors.

11. A heat source detector according to claim 3, wherein said array has 4 sensing elements arrayed in one of said directions.

12. A heat source detector according to claim 11, wherein said array is a 4×

4 array.

13. A heat source detector according to claim 3, wherein said array has 2 sensing elements arrayed in one of said directions.

14. A heat source detector according to claim 3 wherein said array has 3 sensing elements arrayed in one of said directions.

15. A heat source detector according to claim 14, wherein said array is a 2×

3 array.

16. A heat source detector according to claim 1, wherein said center of gravity detecting unit determines said center of gravity by determining respective positions of infrared sensing elements whose intensities exceed a predetermined threshold.

17. A heat source detector according to claim 16, wherein said positions of said sensing elements are weighted according to their respective intensities.

18. A heat source detector according to claim 17, wherein said center of gravity detecting unit determines X and Y components of said center of gravity on the basis of respective X and Y coordinates of said sensing elements.

19. A heat source detector according to claim 16, wherein said center of gravity detecting unit determines X and Y components of said center of gravity on the basis of respective X and Y coordinates of said sensing elements.