Piezoelectric/pyroelectric elements
First Claim
1. A method for the construction of a piezoelectric/pyroelectric element comprising an electrically-polarised laminar stack of individually thin polarisable plastics films, wherein each polarisable plastics film is essentially in face-to-face contact with its two neighbours, there being no significant gas space/pockets between any two adjacent films, in which method:
- (a) the required number of films of the unpolarised but polarisable plastics substance is assembled together in the form of a multilayer sandwich adjacent individual films of which are essentially in face-to-face contact;
(b) the assembly is heated to a temperature somewhat below the deflection temperature of the plastics substance;
(c) while still hot, a polarising electric field is applied across the assembly, from end face to end face;
(d) while still applying the polarising field, the assembly is allowed to cool down; and
(e) after assembly but before cooling adjacent individual films of the assembly are bonded together.
1 Assignment
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Accused Products
Abstract
Piezoelectric and pyroelectric elements made from polarized plastics substances such as polyvinylidene fluoride are of considerable interest in a number of fields. Unfortunately, they also suffer from a number of not insignificant drawbacks. Specifically, the maximum thickness of fully-polarized plastics film obtainable is often not sufficient to give the desired sensitivity.
A very satisfactory thick piezoelectric/pyroelectric element can, however, be made from these plastics films if, instead of using a single film which is itself thick, there is used a laminar stack of individually thin polarizable plastics films each such film being essentially in face-to-face contact with its two neighbors, and there being no significant gas space/pockets between any two adjacent films, the element being made by a method in which: the required number of films of the unpolarized but polarizable plastics substance is assembled together in the form of a multilayer sandwich adjacent individual films of which are essentially in face-to-face contact; the assembly is heated to a temperature somewhat below the deflection temperature of the plastics substance; while still hot, a polarizing electric field is applied across the assembly, from end face to end face; and while still applying the polarizing field, the assembly is allowed to cool down.
26 Citations
8 Claims
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1. A method for the construction of a piezoelectric/pyroelectric element comprising an electrically-polarised laminar stack of individually thin polarisable plastics films, wherein each polarisable plastics film is essentially in face-to-face contact with its two neighbours, there being no significant gas space/pockets between any two adjacent films, in which method:
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(a) the required number of films of the unpolarised but polarisable plastics substance is assembled together in the form of a multilayer sandwich adjacent individual films of which are essentially in face-to-face contact; (b) the assembly is heated to a temperature somewhat below the deflection temperature of the plastics substance; (c) while still hot, a polarising electric field is applied across the assembly, from end face to end face; (d) while still applying the polarising field, the assembly is allowed to cool down; and (e) after assembly but before cooling adjacent individual films of the assembly are bonded together. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification