Infrared Integrated Systems Limited

Stephen Hollock

Stephen George Porter

Bryan Lorrain Humphreys Wilson

A radiation detection apparatus is capable of detecting and locating events, such as a fire or the appearance of an intruder, in a scene under surveillance. The apparatus comprises an array of detector elements, e.g. infrared detectors. The apparatus has two fields of view, namely a first field of view defined by a lens providing a single focussed image of a distant scene on the array and a second field of view defined by a reflector arranged between a plane of the array and a plane of the lens whereby to reflect onto the detector array radiation entering the lens from outside the first field of view. One or more processors are provided to distinguish events in the second field of view from those in the first field of view.

Radiation detection apparatus

A sensor comprising an array of detectors for e.g. infrared radiation of the type for use in security or surveillance application has means for identifying the entry of an object into a first selected area of a scene and means for generating a warning or alarm signal after a first predetermined period of time during which there is no movement of the body within the first selected area.

Use of detector arrays to detect cessation of motion

When an array of thermal detectors with appropriate read-out means is used as a sensor to detect events such as intruders or fire, it may be disabled accidentally or deliberately by placing a mask over the array to shield it from the scene. The act of placing a mask over the array induces a simultaneous transient signal from all of the detectors, or at least a majority of the detectors, and is followed by a period when those detectors give rise only background noise or clutter. The characteristics of these signals is used to generate a warning signal to indicate that the sensor has been disabled.

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Lechlade, United Kingdom

Stephen Hollock