Pyroelectric and other thermal-radiation detectors with film element(s)
First Claim
1. A thermal-radiation detector comprising:
- a flexible continuous film of polymer material having a temperature-dependent electrical characteristic and piezoelectric properties,first and second electrodes at respective first and second opposite faces of the film to form at least one infrared detector element with the polymer material having said temperature-dependent characteristic,a mounting arrangement comprising a plurality of mutually-spaced supports on which the film is mounted so as to by self-supporting between adjacent supports, the supports being spaced out over the whole of the first face on the film so fast to provide support both around a peripheral area of the film and over a non-peripheral area of the film and to provide cavities between the spaced supports such that where the at least one detector element is present at least most of the area of said first face of the polymer film is free of contact with the mounting arrangement,the film being held under tension with at least its peripheral area secured to the mounting arrangement, andthe spacing between adjacent supports in a non-peripheral area proximate to the at least one detector element being sufficiently small and the tension of the film being sufficiently large that the natural frequency of vibration of the self-supporting part of the film between these neighbouring supports is higher than the frequency bandwidth of the detector.
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Accused Products
Abstract
An infrared detector element (20) comprises a flexible continuous film (10) of polymer material which has pyroelectric or other temperature-dependent characteristics and which is also piezoelectric so also generating microphony when it vibrates. In accordance with the invention the mounting arrangement (30,31,32) for the film (10) comprises mutually-spaced supports (32), e.g. tapered ridges (32) of a moulded-plastics substrate (30); the spacing (x) between neighboring supports (32) adjacent to the detector element (20) is sufficiently small and the tension (P) of the film (10) is sufficiently large that the natural frequency of vibration of the parts of the polymer film (10) between these neighboring supports (32) is higher than the frequency bandwidth of the detector, e.g. as determined by the highest operating frequency of a read-out circuit to which the detector element (20) is connected. This arrangement significantly reduces the effects of microphony in contributing to the electrical output of the detector. The ridge portions (32) may form a continuous network around cavities (35) below the detector elements (20 ), and a conduit may extend into each cavity (35) with that at the opposite face (12) of the polymer film (10).
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Citations
12 Claims
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1. A thermal-radiation detector comprising:
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a flexible continuous film of polymer material having a temperature-dependent electrical characteristic and piezoelectric properties, first and second electrodes at respective first and second opposite faces of the film to form at least one infrared detector element with the polymer material having said temperature-dependent characteristic, a mounting arrangement comprising a plurality of mutually-spaced supports on which the film is mounted so as to by self-supporting between adjacent supports, the supports being spaced out over the whole of the first face on the film so fast to provide support both around a peripheral area of the film and over a non-peripheral area of the film and to provide cavities between the spaced supports such that where the at least one detector element is present at least most of the area of said first face of the polymer film is free of contact with the mounting arrangement, the film being held under tension with at least its peripheral area secured to the mounting arrangement, and the spacing between adjacent supports in a non-peripheral area proximate to the at least one detector element being sufficiently small and the tension of the film being sufficiently large that the natural frequency of vibration of the self-supporting part of the film between these neighbouring supports is higher than the frequency bandwidth of the detector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification