Passive infrared intrusion detection system

Abstract

The invention comprises a passive infrared intrusion detector including a lamp for locating the zones being protected by the detector. The detector includes a heat sensor, a lens system for receiving and focusing the body heat of an intruder on the heat sensor, and electrical circuitry responsive to the heat sensor for actuating an alarm or detection signal when the body heat of an intruder is detected. The zone locator lamp is positioned near the heat sensor and its light passes through a lens in the general direction of a zone to be protected. The light parallels a portion of radiation which is focused on the heat sensor by another lens. If the light can be observed from a given position in front of the detector, that position is in a zone being observed by the detector and body heat radiated from that zone will be focused on the heat sensor. Thus, zones protected by the intrusion detector can be established by adjusting the position of the detector until light from the zone locator lamp is observed. Once these zones are established, the lamp may be disconnected and the intrusion detector placed in the "ready" or "stand by" mode.

What is claimed is: 
     
       1. In a passive infrared intrusion detector of the type including a heat sensor for detecting a change in temperature caused by a passing intruder, a lens mounted in front of said heat sensor for receiving infrared radiation from the body of said intruder and focusing said radiation on said heat sensor, and means coupled to said heat sensor for actuating a signal when said heat sensor detects said temperature change, the improvement comprising:   a lamp for emitting visible light positioned within said intrusion detector proximate to said heat sensor,   said lens including a first lens segment positioned to receive infrared radiation from a first zone to be protected and focus a portion of said radiation on said heat sensor, and a second lens segment positioned to receive radiation from a second zone to be protected and focus a portion of said radiation on said heat sensor,   said second lens segment being positioned relative to said lamp and said heat sensor such that light from said lamp passes through said second lens segment and parallels that portion of radiation from said first zone which is focused on said heat sensor by said first lens segment,   wherein said first zone may be located by adjusting said intrusion detector so that light from said lamp is observed in said first zone.   
     
     
       2. An intrusion detector as claimed in claim 1 wherein the top edge of said second lens segment is integrally joined to the bottom edge of said first lens segment. 
     
     
       3. An intrusion detector as claimed in claim 1 wherein said first and second lens segments are subdivided into a number of corresponding sections, each having a different field of view. 
     
     
       4. An intrusion detector as claimed in claim 1 wherein said first and second lens segments are collimating lenses. 
     
     
       5. An intrusion detector as claimed in claim 1 including means operatively associated with said lamp for deenergizing said lamp after said first zone has been located. 
     
     
       6. An intrusion detector as claimed in claim 1 further including means for movably mounting said lens relative to said heat sensor and said lamp. 
     
     
       7. An intrusion detector as claimed in claim 1 wherein said lamp is a light emitting diode (LED). 
     
     
       8. A method of locating zones protected by a passive intrusion detector of the type including a sensor for detecting infrared radiation from the body of an intruder, a lens for focusing said radiation of said sensor, and means coupled to said sensor for actuating a signal when the body heat of an intruder is sensed, comprising: providing a first lens segment for receiving infrared radiation from a first zone to be protected and focusing a portion of said radiation on said sensor,   providing a second lens segment for receiving infrared radiation from a second zone to be protected and focusing a portion of said radiation on said sensor,   providing a lamp which emits visible light,   positioning said lamp relative to said sensor and said second lens segment such that light emitted from said lamp passes through said second lens segment and parallels that portion of radiation from said first zone which is focused on the sensor by said first lens segment,   selecting a first zone to be protected, and   adjusting said intrusion detector so that light from said lamp is visible in said first zone through said second lens segment.   
     
     
       9. The method of claim 8 further including the step of: deenergizing said lamp after said zone is located.   
     
     
       10. The method of claim 8 wherein said lamp is a light emitting diode (LED). .Iadd. 
     
     
       11.  In a passive infrared intrusion detector of the type including an infrared sensing element, responsive to infrared radiation emanating from within at least one zone comprising an angular region of space desired to be protected and including means coupled to said sensing element for actuating a signal in response to changes in said infrared radiation within said zone, the improvement comprising: a lamp for emitting visible light and means for focusing said visible light to be emitted from said infrared intrusion detector into said angular region of space, said light being emitted in a direction generally parallel to the direction of radiation from said zone to said sensing element such that the boundaries of said zone are defined by the location of said detector and the angular region of space in which said light is visually observable. .Iaddend. .Iadd.12. An intrusion detector according to claim 11 wherein said focusing means comprises a lens. .Iaddend. .Iadd.13. An intrusion detector according to claim 12 wherein said lens has a first lens segment for focusing infrared radiation emanating from said zone onto said sensing element and a second lens segment for focusing light from said lamp into said zone. .Iaddend. .Iadd.14. An intrusion detector according to claim 13 wherein said second lens segment is arranged to focus infrared radiation 
     
     
        from a second zone onto said sensing element. .Iaddend. .Iadd.15.  An intrusion detector according to claim 13 wherein the top edge of said second lens segment is integrally joined to the bottom edge of said first lens segment. .Iaddend. .Iadd.16. An intrusion detector according to claim 13 wherein said first and second lens segments are subdivided into a number of corresponding sections, each having a different field of view. .Iaddend. .Iadd.17. An intrusion detector according to claim 12 wherein said lens is a collimating lens. .Iaddend. .Iadd.18. An intrusion detector according to claim 13 wherein said first and second lens segments are collimating lenses. .Iaddend. .Iadd.19. An intrusion detector according to claim 11 including means operatively associated with said lamp for selectively deenergizing said lamp. .Iaddend. .Iadd.20. An intrusion detector according to claim 12 further including means for moveably mounting said lens relative to said sensing element and said lamp. .Iaddend. .Iadd.21. An intrusion detector according to claim 13 further including means for moveably mounting said lens relative to said sensing element and said lamp. .Iaddend. .Iadd.22. An intrusion detector according to claim 11 wherein said lamp is a light emitting diode (LED). .Iaddend. 
     
     
        .Iadd.23.  A method of locating a first zone which comprises an angular region of space to be protected by a passive infrared intrusion detector of the type including an infrared sensing element arranged to receive infrared radiation emanating within said zone, and including means coupled to said sensing element for actuating a signal in response to changes in said infrared radiation within said zone comprising: providing said detector with a lamp arranged to emit visible light and means for focusing visible light from said lamp into said zone, said light being emitted in a direction generally parallel to the direction of radiation emanating from said zone to said sensing element; selecting a desired zone to be protected; and adjusting said detector so that light from said lamp is visually observable within said desired zone. .Iaddend. .Iadd.24. The method according to claim 23 wherein the lamp is deenergized after said step of adjusting. .Iaddend.