Infrared Integrated Systems Limited

John Lindsay Galloway

Stephen George Porter

Bryan Lorrain Humphreys Wilson

A surveillance system using an array of detectors onto which energy from the scene under surveillance is focused can indicate the direction of an event that has been recognized. The invention uses two or more arrays to locate events in three dimensions, and to define regions within the three dimensional space being surveyed. The events are located by detecting which elements from the respective arrays are stimulated by the occurrence of an event, and determining the location of the event to be at the intersection of the fields of view of the stimulated elements.

Location of events in a three dimensional space under surveillance

An optical detection system for forming an image of a field of view in an object plane onto an image plane in which the electromagnetic radiation image is transmitted to a detector array at the image plane via an optical distorting element such as a reflector, so as to impose a non linear relationship between areas in the image and object planes.

Use of distorting optics in imaging systems

Arrays of pyroelectric elements are used in surveillance systems by focusing the radiation from a scene on to them and examining the output from the array. If an object is moved into the scene and left stationary, it will hinder the subsequent operation of the system by masking part of the scene from the field of view of the array; this fault condition may be detected by the following procedure. At intervals arrangements are made to move the image of the scene to and from across the array using a suitable transducer and the outputs from the array are examined. The outputs from the array when the scene is in its normal condition and the image is moved across the array comprise a set of signals corresponding to a reference image, which may be compared with the corresponding outputs from the array when the image is moved across the array on a subsequent occasion. Change between the reference image signals and subsequent image signals are interpreted in terms of the introduction to, or removal of, objects from the scene.

Detection of obstacles in surveillance systems using pyroelectric arrays

A method and apparatus for an event detector using an array of passive infrared detector elements, which uses interchangeable spectral filters and lenses to permit detection of a range of event types, which normally each require individual detectors with specific spectral/optical designs.

Multipurpose detector

In order to determine the position of an object within an area viewed by a single detector of an array, signals from detectors adjacent to the single detector are compared with each other and/or the single detector. The method can be extended to larger objects to ascertain the locations of edges.

Detection of position and motion of sub-pixel images

An image of a scene is focused onto a two dimensional array of passive infrared sensing elements mounted on and connected to an integrated circuit, and used to detect the location of events within the scene; for example, movement, change in temperature, or the emission of a gas. In this invention knowledge of the location of the event is derived from the detection of signals from one or more elements of the array, and is used to control the operation of a mechanism such that a portion of the scene including the event location is imaged onto a video imaging device operating in the visible or near infrared. Such mechanisms include a zoom lens or mirror arrangement and mechanical scanning in elevation and/or azimuth. Examples of suitable imaging devices for use with the thermal detector array include CCD camera chips and other electrically scanned silicon photovoltaic arrays. The CCD array might for example be used in a CCD camera, which is used to identify an intruder, or to read the number plate of a car. The event located within the scene may in addition be illuminated with a visible or infrared beam or a searchlight switched on and/or directed by the identification of an event by the thermal array.

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Towcester, United Kingdom

John Lindsay Galloway