Particle detector, system and method

• US 9,007,223 B2
• Filed: 07/08/2013
• Issued: 04/14/2015
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Garrett Thermal Systems Ltd. (Honeywell International Inc.)
• Original Assignee: Xtralis Technologies Ltd (Honeywell International Inc.)
• Inventors: Knox, Ron, Boettger, Karl, Ajay, Kemal
• Primary Examiner(s): Lau, Hoi
• Application Number:
  US13/936,418
• Publication Number:
  US 20140022547A1
• Time in Patent Office: 645 Days
• Field of Search: 340/628, 340/629, 340/630, 340/693.6, 382/218, 382/128, 382/103, 386/227, 356/5.04, 356/5.03, 356/438, 235/454
• US Class Current: 340/628
• CPC Class Codes: G01N 15/1433 using image recognition
• CPC Class Codes: G01N 2021/1765 Method using an image detector and processing of image signal
• CPC Class Codes: G01N 21/17 Systems in which incident light is modified in accordance with the properties of the material investigated where the material investigated is optically excited causing a change in wavelength of the incident light G01N21/63
• CPC Class Codes: G01N 21/49 within a body or fluid
• CPC Class Codes: G01N 21/532 with measurement of scattering and transmission
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 33/0031 comprising two or more sensors, e.g. a sensor array
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/95 for meteorological use
• CPC Class Codes: G01S 7/4873 by deriving and controlling a threshold value
• CPC Class Codes: G01S 7/4876 by removing unwanted signals G01S7/495 takes precedence
• CPC Class Codes: G08B 17/103 using a light emitting and receiving device
• CPC Class Codes: G08B 17/107 for detecting light-scattering due to smoke
• CPC Class Codes: G08B 17/117 by using a detection device for specific gases, e.g. combustion products, produced by the fire G08B17/103, G08B17/11 take precedence
• CPC Class Codes: G08B 17/125 by using a video camera to detect fire or smoke
• CPC Class Codes: G08B 25/10 using wireless transmission systems G08B25/009 takes precedence
• CPC Class Codes: G08B 29/043 of fire detection circuits
• 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: G08B 29/24 Self-calibration, e.g. compensating for environmental drift or ageing of components
• CPC Class Codes: Y02A 90/10 : Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

The invention provides use of one or more emitted beams of radiation (16), for example, laser beam(s), in combination with an image capturing means (14), for example, one or more video cameras and/or optical elements to detect particles (30), for example, smoke particles, located in an open space (12).

Claims

1. A method performed by a particle detection system, said method being configured to synchronise between a light source of the particle detection system and an image capturing means of the particle detection system, the method comprising:

allowing the light source to oscillate on and off at a predetermined rate;

identifying the light source in video images captured by the image capturing means and;

continually modifying the image capturing means frame rate to remain in synchronisation with the oscillation of the light source.

2. A method as claimed in claim 1 wherein the light source is fitted with a secondary light source having a wide angle of emission wherein the step of identifying the light source comprises identifying the secondary light source.

3. A method as claimed in claim 2 further comprising the step of:

flashing the secondary light source in a predetermined timing relationship with the light source to facilitate locating the light source in the image capturing means image.

4. A method as claimed in claim 2, wherein the secondary light source is a LED.

5. A method as claimed in claim 4 wherein the secondary light source flashes in one or more of:

a periodic pattern;

a pseudorandom sequence.

6. A method as claimed in claim 2, wherein the secondary light source operates in synchronisation with the light source.

7. A method as claimed in claim 1 wherein the image capturing means has an initial frame rate that approximates the rate of an oscillator of the light source, and the method further comprises;

identifying flashing of the light source;

varying the phase of the image capturing means frame rate to maintain a timing relationship between image capturing means exposures and the light source.

8. A method as claimed in claim 7 wherein which includes determining a rate of change of phase between an oscillator of the light source and an oscillator of the image capture means.

9. A method as claimed in claim 8 which includes using a phase locked loop feedback mechanism to adjust a frame rate of the image capturing means to maintain a fixed phase with the light source to remain in synchronisation therewith.

10. A method as claimed in claim 1 wherein a frequency of the light source oscillator is altered to be one of:

the same as;

a multiple of;

a sub multiple of an AC mains electricity supply frequency.

11. A method as claimed in claim 10 which includes:

sensing the mains electricity supply frequency directly from the mains supply.

12. A method as claimed in claim 10 wherein the step of sensing the mains electricity supply frequency directly from the mains supply comprises:

sensing the mains electricity supply frequency using an inductive or capacitive coupling.

13. A method as claimed in claim 10 which includes:

sensing the mains electricity supply frequency using a photoelectric detector arranged to receive light from artificial lighting.

14. A method as claimed in claim 2 which includes:

providing the light source with a battery backed power supply; and

wherein the method further includes;

dropping the light source duty cycle when operating on backup power to indicate that backup power is being used.

15. A method as claimed in claim 2 wherein status information is transmitted via modulation of the light source or secondary light source.

19. A method as claimed in claim 6, wherein he image capturing means has an initial frame rate that approximates the rate of the oscillator of the light source, wherein the method further comprises;

identifying flashing of the secondary light source;

varying a phase of the image capturing means frame rate to maintain a timing relationship between image capturing means exposures and the light source.

16. Apparatus adapted to detect particles in a region, said apparatus comprising:

a light source arranged to emit a beam of light across the region said beam of light oscillating on and off at a predetermined rate,

image capturing system configured to generate video images of the region;

a processor configured to;

identify the light source in one or more video images and to modify the image capturing system'"'"'s frame rate to remain in synchronisation with the oscillation of the beam of light; and

detect a variation in the video images to indicate the presence of particles in the region.

17. An apparatus as claimed in claim 16 wherein the light source is fitted with a secondary light source comprising a wide angle of emission.

18. An apparatus as claimed in claim 17, wherein the secondary light source is a LED.