Smoke detector

• US 6,653,942 B2
• Filed: 12/03/2001
• Issued: 11/25/2003
• Est. Priority Date: 12/08/1999
• Status: Expired due to Term

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Kadwell, Brian J., Pattok, Greg R.
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US10/005,436
• Publication Number:
  US 20020060632A1
• Time in Patent Office: 722 Days
• Field of Search: 340/630, 340/628, 356/438, 356/436, 250/573, 250/574
• US Class Current: 340/630
• CPC Class Codes: G08B 17/107 for detecting light-scattering due to smoke
• CPC Class Codes: G08B 17/113 Constructional details
• CPC Class Codes: G08B 17/125 by using a video camera to detect fire or smoke
• CPC Class Codes: G08B 29/043 of fire detection circuits

Abstract

A smoke detector includes a housing defining a dark chamber admitting test atmosphere. A light receiver is disposed within the chamber. A scatter emitter is positioned within the chamber such that light strikes the receiver when reflected off particles suspended in the test atmosphere. An obscuration emitter is positioned within the chamber such that light emitted is directed to the receiver unless obstructed by particles suspended in the test atmosphere. A smoke detect signal is generated responsive to a measurement made responsive to the scatter emitter and/or the obscuration emitter.

Claims

1. A particle detector, comprising:

a housing admitting a test atmosphere;

a first emitter positioned for supplying a light beam into the test atmosphere, where a received portion of the light beam emitted by the first emitter is proportional to the amount of high reflectivity particles present in the test atmosphere;

a second emitter positioned for supplying a light beam into the test atmosphere, where a received portion of the light beam emitted by the second emitter is inversely proportional to the amount of low reflectivity particles present in the test atmosphere;

at least one receiver positioned to receive light supplied by the first and second emitters; and

a controller coupled to the first emitter, the second emitter and the at least one receiver, the controller using the amount of particles sensed using one of the first and second emitters to alter an alarm threshold of the remaining emitter.

2. The particle detector of claim 1, wherein the controller is also configured to change a particle detector sensor cycle when a high reflectivity particle level crosses an initial first emitter threshold, and wherein the rate of the particle detector sensor cycle determines the frequency with which at least one of the first and second emitters emits light.

3. The particle detector of claim 2, wherein the controller causes the second emitter to generate light only after the high reflectivity particle level crosses the initial first emitter threshold.

4. The particle detector of claim 3, wherein a first emitter alarm threshold is modified to occur at a lower high reflectivity particle level when a second emitter threshold is exceeded.

5. The particle detector of claim 2, wherein the controller determines the high reflectivity particle level by calculating an initial first emitter ratio whose numerator is related to a first emitter conduction current provided by the receiver in response to light from the first emitter and whose denominator is related to a first emitter dark current provided by the receiver in response to no light from the first emitter.

6. The particle detector of claim 5, wherein the controller compensates for changing environmental conditions and degraded performance of the particle detector by altering a first emitter reference ratio that is used to provide a normalized first emitter ratio that replaces the initial first emitter ratio, wherein the normalized first emitter ratio is used to determine the high reflectivity particle level, and wherein the first emitter reference ratio corresponds to a no particle first emitter ratio that is occasionally updated under a no particle condition.

7. The particle detector of claim 6, wherein the controller determines the low reflectivity particle level by calculating a percentage change in obscuration from one particle detector sensor cycle to another particle detector sensor cycle, and wherein a detected obscuration is related to a difference between a conduction time in which a second emitter conduction current is provided by the receiver in response to light from the second emitter and a second emitter dark time in which a dark current is provided by the receiver in response to no light from the second emitter.

8. The particle detector of claim 7, wherein the controller compensates for changing environmental conditions and degraded performance of the particle detector by setting an obscuration reference, and wherein the obscuration reference is utilized as a base for later determinations of percentage change in obscuration.

9. The particle detector of claim 8, wherein the obscuration reference is set when the first emitter measurement crosses the initial first emitter threshold.

10. A particle detector, comprising:

a housing admitting a test atmosphere;

a first emitter positioned for supplying a light beam into the test atmosphere;

a first receiver positioned to receive light supplied by the first emitter after the light has traveled through the test atmosphere, where a received portion of the light beam emitted by the first emitter and received by the first receiver is inversely proportional to the amount of low reflectivity particles present in the test atmosphere;

a second receiver positioned to receive light from the first emitter, wherein the light received by the second receiver travels along a path isolated from the test atmosphere; and

a controller coupled to the first emitter, the first receiver and the second receiver, the controller using the light sensed using the second receiver as a reference for the light sensed using the first receiver to determine the amount of particles present in the test atmosphere.

11. The particle detector of claim 10, further including:

a second emitter positioned for supplying a light beam into the test atmosphere, where a received portion of the light emitted by the second emitter and received by the first receiver is proportional to the amount of high reflectivity particles present in the test atmosphere, and where the second emitter is coupled to the controller and the controller uses the amount of particles sensed using one of the first and second emitters to alter an alarm threshold of the remaining emitter.

12. The particle detector of claim 11, wherein the controller is also configured to change a particle detector sensor cycle when a high reflectivity particle level crosses an initial Second emitter threshold, and wherein the rate of the particle detector sensor cycle determines the frequency with which at least one of the first and second emitters emits light.

13. The particle detector of claim 12, wherein the controller causes the first emitter to generate light only after the high reflectivity particle level crosses the initial second emitter threshold.

14. The particle detector of claim 13, wherein a second emitter alarm threshold is modified to occur at a lower high reflectivity particle level when a first emitter threshold is exceeded.

15. The particle detector of claim 12, wherein the controller determines the high reflectivity particle level by calculating an initial second emitter ratio whose numerator is related to a second emitter conduction current provided by the first receiver in response to light from the second emitter and whose denominator is related to a second emitter dark current provided by the first receiver in response to no light from the second emitter.

16. The particle detector of claim 15, wherein the controller compensates for changing environmental conditions and degraded performance of the particle detector by altering a second emitter reference ratio that is used to provide a normalized second emitter ratio that replaces the initial second emitter ratio, wherein the normalized second emitter ratio is used to determine the high reflectivity particle level, and wherein the second emitter reference ratio corresponds to a no particle second emitter ratio that is occasionally updated under a no particle condition.

17. The particle detector of claim 16, wherein the controller determines the low reflectivity particle level by calculating a percentage change in obscuration from one particle detector sensor cycle to another particle detector sensor cycle, and wherein a detected obscuration is related to a difference between a conduction time in which a first emitter conduction current is provided by the first receiver in response to light from the first emitter and a first emitter dark time in which a dark current is provided by the first receiver in response to no light from the first emitter.

18. The particle detector of claim 17, wherein the controller compensates for changing environmental conditions and degraded performance of the particle detector by setting an obscuration reference, and wherein the obscuration reference is utilized as a base for later determinations of percentage change in obscuration.

19. The particle detector of claim 18, wherein the obscuration reference is set when the second emitter measurement crosses the initial second emitter threshold.

20. A particle detector, comprising:

a housing admitting a test atmosphere;

a first emitter positioned for supplying a light beam into the test atmosphere, where a received portion of the light beam emitted by the first emitter is inversely proportional to the amount of low reflectivity particles present in the test atmosphere;

a second emitter positioned for supplying a light beam into the test atmosphere, where a received portion of the light emitted by the second emitter is proportional to the amount of high reflectivity particles present in the test atmosphere;

a receiver positioned to receive light supplied by the first and second emitters;

a mounting structure for mechanically coupling the first emitter and the receiver to each

an optical element positioned to direct the light beam emitted by the first emitter to the receiver, wherein misorientation of at least one of the optical element and the mounting structure with respect to each other is facilitated while maintaining the alignment of the receiver with the first emitter.

21. The particle detector of claim 20, further including:

a controller coupled to the first and second emitters and the receiver, the controller using the amount of particles sensed using one of the first and second emitters to alter an alarm threshold of the remaining emitter.

22. The particle detector of claim 21, wherein the controller is also configured to change a particle detector sensor cycle when a high reflectivity particle level crosses an initial second emitter threshold, and wherein the rate of the particle detector sensor cycle determines the frequency with which at least one of the first and second emitters emits light.

23. The particle detector of claim 22, wherein the controller causes the first emitter to generate light only after the high reflectivity particle level crosses the initial second emitter threshold.

24. The particle detector of claim 23, wherein a second emitter alarm threshold is modified to occur at a lower high reflectivity particle level when a first emitter threshold is exceeded.

25. The particle detector of claim 22, wherein the controller determines the high reflectivity particle level by calculating an initial second emitter ratio whose numerator is related to a second emitter conduction current provided by the receiver in response to light from the second emitter and whose denominator is related to a second emitter dark current provided by the receiver in response to no light from the second emitter.

26. The particle detector of claim 25, wherein the controller compensates for changing environmental conditions and degraded performance of the particle detector by altering a second emitter reference ratio that is used to provide a normalized second emitter ratio that replaces the initial second emitter ratio, wherein the normalized second emitter ratio is used to determine the high reflectivity particle level, and wherein the second emitter reference ratio corresponds to a no particle second emitter ratio that is occasionally updated under a no particle condition.

27. The particle detector of claim 26, wherein the controller determines the low reflectivity particle level by calculating a percentage change in obscuration from one particle detector sensor cycle to another particle detector sensor cycle, and wherein a detected obscuration is related to a difference between a conduction time in which a first emitter conduction current is provided by the receiver in response to light from the first emitter and a first emitter dark time in which a dark current is provided by the receiver in response to no light from the first emitter.

28. The particle detector of claim 27, wherein the controller compensates for changing environmental conditions and degraded performance of the particle detector by setting an obscuration reference, and wherein the obscuration reference is utilized as a base for later determinations of percentage change in obscuration.

29. The particle detector of claim 28, wherein the obscuration reference is set when the second emitter measurement crosses the initial second emitter threshold.

30. The particle detector of claim 20, wherein the optical element is configured to provide a substantially fixed distance between an incoming light beam emitted by the first emitter and impinging on the optical element and an outgoing light beam that is associated with the incoming light beam and is provided by the optical element to the receiver, and wherein the substantially fixed distance is maintained independent of the position of the mounting structure with respect to the optical element and corresponds to the spacing between the first emitter and the receiver.

31. A particle detector, comprising:

a housing admitting a test atmosphere;

a first emitter positioned for supplying a light beam into the test atmosphere;

a first receiver positioned to receive light supplied by the first emitter after the light has traveled through the test atmosphere, where a received portion of the light beam emitted by the first emitter and received by the first receiver is proportional to the amount of high reflectivity particles present in the test atmosphere;

a second receiver positioned to receive light from the first emitter, wherein the light received by the second receiver travels along a path isolated from the test atmosphere; and

a controller coupled to the first emitter, the first receiver and the second receiver, the controller using the light sensed using the second receiver as a reference for the light sensed using the first receiver to determine the amount of particles present in the test atmosphere.

32. The particle detector of claim 31, further including:

a second emitter positioned for supplying a light beam into the test atmosphere, where a received portion of the light emitted by the second emitter and received by the first receiver is inversely proportional to the amount of low reflectivity particles present in the test atmosphere, and where the second emitter is coupled to the controller and the controller uses the amount of particles sensed using one of the first and second emitters to alter an alarm threshold of the remaining emitter.

33. A particle detector, comprising:

a housing admitting a test atmosphere;

an emitter positioned for supplying a light beam into the test atmosphere;

a receiver positioned to receive light supplied by the emitter;

a mounting structure for mechanically coupling the emitter and the receiver to each other such that a spacing between the emitter and the receiver is substantially constant; and

an optical element positioned to direct a substantial portion of the light beam emitted by the emitter to the receiver, wherein a distance between an incoming portion of the light beam impinging on the optical element and an outgoing portion of the light beam leaving the optical element is substantially the same as the spacing between the emitter and the receiver, and wherein the distance is maintained independent of the position of the mounting structure with respect to the optical element.

34. The particle detector of claim 33, wherein the optical element is a right angle mirror.