Particle detection

• US 9,702,803 B2
• Filed: 04/16/2015
• Issued: 07/11/2017
• Est. Priority Date: 11/15/2007
• Status: Active Grant

• Current Assignee: Garrett Thermal Systems Ltd. (Honeywell International Inc.)
• Original Assignee: Garrett Thermal Systems Ltd. (Honeywell International Inc.)
• Inventors: Knox, Ron, Ajay, Kemal, Boettger, Karl
• Primary Examiner(s): Ton, Tri T
• Application Number:
  US14/687,969
• Publication Number:
  US 20150241330A1
• Time in Patent Office: 817 Days
• Field of Search: 356335-343
• CPC Class Codes: G01N 15/06 Investigating concentration of particle suspensions by weighing G01N5/00; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10
• CPC Class Codes: G01N 15/075 by optical means
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke
• CPC Class Codes: G08B 17/125 by using a video camera to detect fire or smoke
• CPC Class Codes: G08B 29/18 Prevention or correction of operating errors G08B29/02, G08B29/12 take precedence
• CPC Class Codes: G08B 29/185 Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

A particle detection system (100), such as an active video smoke detection system, includes at least one illumination means (102) for directing a beam (106) of radiation through at least part of the air volume being monitored (110), an image sensor (104) is positioned to capture images of at least part of a beam (106) from illumination means (102); and means to analyze (107) the captured images to detect the presence of particles within the volume. At least 29 different aspects are described for improving the sensitivity, usability, and robustness of particle detection. These include, for example, configuring illumination means (102) to create a curtain of light or a rapidly-scanned beam across the air volume (110), and configuring a reflector to steer or change direction of a beam reflected from illumination means (102).

Claims

1. A method in an active video smoke detection (AVSD) system, the AVSD system including:

at least one primary light source configured to emit a beam of light across a volume being monitored;

an image sensor having a field of view and arranged to capture images of a least part of the beam of light; and

means to analyze images captured by the image sensor to detect the presence of particles within the volume on the basis of light scattered from the beam and captured in the images;

said method comprising;

emitting the beam of light across the volume being monitored at a primary beam position to enable detection of particles within the volume based on the analysis of images captured by the image sensor on the basis of light scattered from the beam at the primary beam position and captured in the images; and

determining an intrusion of an object into the field of view of the image sensor such that the object impedes the image sensor'"'"'s view of the beam in the primary beam position when detecting particles, by

(a) scanning a beam of light across a part of the volume being monitored to illuminate a region within the volume that lies between a primary beam position and the image capture means, and

(b) analyzing the output of the image sensor to determine whether an object has impinged upon the beam of light emitted in step (a), to identify an object that blocks a line of sight between the image capture means and the beam of light when it is in its primary beam position.

2. A method as claimed in claim 1, wherein the step of analyzing the output of the image sensor, includes identifying the presence of any one of the following features in the sensor output:

reflection, refraction, diffraction pattern or glint.

3. A method as claimed in claim 1, wherein step (a) is performed using a primary light source of the AVSD system.

4. A method as claimed in claim 1, wherein the AVSD system includes at least one secondary light source that is not used for particle detection and step (a) is performed with the said secondary light source.

5. A method as claimed in claim 1, wherein the AVSD system includes at least one secondary light source for monitoring a portion of the field of view of the image sensor that is affected by a primary light source;

and the method includes;

analysing the output of the image sensor to determining an intrusion of an object between the secondary light source and the image sensor.

6. A method as claimed in claim 5, wherein the secondary light source covers an extended area of the field of view of the image sensor.

7. A method as claimed in claim 1, which further includes:

indicating a fault in the event that it is determined in step (b) that an object has impinged upon the beam of light.

8. An active video smoke detection system (AVSD) including:

at least one primary light source configured to emit a beam of light across a volume being monitored, wherein the at least one primary light source is arranged to emit a beam of light across a volume being monitored at a primary beam position to enable detection of particles within the volume;

an image sensor having a field of view and arranged to capture images of a least part of the beam of light;

means to scan a beam of light across part of the volume being monitored configured to cause the scanned beam to illuminate a region within the volume that lies between a primary beam position and the image capture means; and

means to analyse images captured by the image sensor to detect the presence of particles within the volume on the basis of light scattered from the beam and captured in the images;

said AVSD system being configured to perform a method as claimed in claim 1.

9. An AVSD system as claimed in claim 8, which includes at least one secondary light source.

10. An AVSD system as claimed in claim 9, wherein the secondary light source is arranged to emit a beam of light across at least part of the field of view of the image sensor includes illuminating a background behind the volume being monitored;

and wherein

means to analyse images is configured to identify the presence of a shadow in the sensor output.

11. An AVSD system as claimed in claim 10, wherein the secondary light source projects a pattern of light onto a background surface.

12. An AVSD system as claimed in claim 9, wherein the at least one secondary light source is arranged in a portion of the field of view of the image sensor that is affected by a primary light source and emits light that is received by the image sensor;

wherein the means to analyse images is arranged to detect an obscuration of the secondary light source to determine an intrusion of an object between the secondary light source and the image sensor.

13. An AVSD system as claimed in claim 12, wherein the secondary light source covers an extended area of the field of view of the image sensor.

14. An AVSD system as claimed in claim 8, wherein the scanned beam is emitted by the primary light source.

15. An AVSD system as claimed in claim 8, wherein the scanned beam is emitted by the secondary light source.

16. A method as claimed in any one of claim 2, wherein step (a) is performed using a primary light source of the AVSD system.

17. A method as claimed in claim 2, wherein the AVSD system includes at least one secondary light source that is not used for particle detection and step (a) is performed with the said secondary light source.

18. A method as claimed in claim 2, wherein the AVSD system includes at least one secondary light source for monitoring a portion of the field of view of the image sensor that is affected by a primary light source;

and the method includes;

analysing the output of the image sensor to determining an intrusion of an object between the secondary light source and the image sensor.

19. A method as claimed in claim 3, wherein the AVSD system includes at least one secondary light source for monitoring a portion of the field of view of the image sensor that is affected by a primary light source;

and the method includes;

analysing the output of the image sensor to determining an intrusion of an object between the secondary light source and the image sensor.

20. A method as claimed in claim 4, wherein the AVSD system includes at least one secondary light source for monitoring a portion of the field of view of the image sensor that is affected by a primary light source;

and the method includes;

analysing the output of the image sensor to determining an intrusion of an object between the secondary light source and the image sensor.

21. A method as claimed in claim 2, which further includes:

indicating a fault in the event that it is determined in step (b) that an object has impinged upon the beam of light.

22. A method as claimed in claim 3, which further includes:

indicating a fault in the event that it is determined in step (b) that an object has impinged upon the beam of light.

23. A method as claimed in claim 4, which further includes:

indicating a fault in the event that it is determined in step (b) that an object has impinged upon the beam of light.

24. A method as claimed in claim 5, which further includes:

indicating a fault in the event that it is determined in step (b) that an object has impinged upon the beam of light.