Particle detection

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 moans ( 102 ); and means to analyse ( 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 ).

1 - 20 . (canceled) 
     
     
         21 . A method in an AVSD system, comprising:
 detecting a presence of scattered light over a period of time; and   analysing at least one characteristic of the sensed light over at least a portion of the volume to determine whether the light has been scattered by solid object or particles in the volume being monitored.   
     
     
         22 . A method as claimed in  claim 21 , wherein the method includes indicating a fault if a solid object is detected. 
     
     
         23 . A method as claimed in  claim 21 , wherein the method includes repeating any one or more of steps of the method to confirm that an edge of a solid object has been detected. 
     
     
         24 . A method as claimed in  claim 23 , wherein the method includes indicating a fault if a solid object is detected. 
     
     
         25 . A method as claimed in  claim 21 , wherein the method further includes scanning a beam from a primary light source across an extended portion of the volume and detecting light scattered from the swept beam. 
     
     
         26 . A method as claimed in  claim 25 , wherein the method includes repeating any one or more of steps of the method to confirm that an edge of a solid object has been detected. 
     
     
         27 . A method as claimed in  claim 21 , wherein the method includes analysing the detected light to identify a characteristic of detected light signifying an edge of a solid object. 
     
     
         28 . A method as claimed in  claim 27 , wherein the method further includes scanning a beam from a primary light source across an extended portion of the volume and detecting light scattered from the swept beam. 
     
     
         29 . A method as claimed in  claim 21 , wherein the method further includes scanning a beam from a primary light source across an extended portion of the volume and detecting light scattered from the swept beam. 
     
     
         30 . A method in an AVSD system, comprising:
 detecting a presence of scattered light over a period of time;   analysing at least one characteristic of the sensed light over at least a portion of the volume to determine whether the light has been scattered by solid object or particles in the volume being monitored; and   analysing an intensity profile of the received light over time or space to determine the presence of a solid object.   
     
     
         31 . A method as claimed in  claim 30 , wherein the method includes indicating a fault if a solid object is detected. 
     
     
         32 . A method as claimed in  claim 30 , wherein the method includes repeating any one or more of steps of the method to confirm that an edge of a solid object has been detected. 
     
     
         33 . A method as claimed in  claim 30 , wherein the method includes analysing an intensity profile of the received light over time or space to determine the presence of a solid object. 
     
     
         34 . A method as claimed in  claim 30 , wherein the method includes analysing the detected light to identify a characteristic of detected light signifying an edge of a solid object. 
     
     
         35 . A method as claimed in  claim 30 , wherein the method further includes scanning a beam from a primary light source across an extended portion of the volume and detecting light scattered from the swept beam. 
     
     
         36 . A method in an AVSD system, comprising:
 detecting a presence of scattered light over a period of time;   analysing at least one characteristic of the sensed light over at least a portion of the volume to determine whether the light has been scattered by solid object or particles in the volume being monitored; and   analysing an intensity profile of the received light over time or space to determine the presence of a solid object.   
     
     
         37 . A method as claimed in  claim 36 , wherein the method includes indicating a fault if a solid object is detected. 
     
     
         38 . A method as claimed in  claim 36 , wherein the method includes repeating any one or more of steps of the method to confirm that an edge of a solid object has been detected. 
     
     
         39 . A method as claimed in  claim 36 , wherein the method includes analysing the detected light to identify a characteristic of detected light signifying an edge of a solid object. 
     
     
         40 . A method as claimed in  claim 36 , wherein the method further includes scanning a beam from a primary light source across an extended portion of the volume and detecting light scattered from the swept beam.