Pressure sensitive switch

• US 4,158,117 A
• Filed: 11/08/1977
• Issued: 06/12/1979
• Est. Priority Date: 12/02/1976
• Status: Expired due to Term

• Current Assignee: Marconi Co Ltd (BAE Systems Plc)
• Original Assignee: Marconi Co Ltd (BAE Systems Plc)
• Inventors: Quilliam, Robert M., Gallantree, Howitt R., Watt, Andrew J.
• Primary Examiner(s): Price, William
• Assistant Examiner(s): Pollard, Steven M.
• Application Number:
  US05/849,609
• Time in Patent Office: 581 Days
• Field of Search: 200/181, 200/159 R, 200/159 B, 200/262, 200/269, 200/83 R, 200/83 A, 200/83 B, 200/83 J, 200/83 Y, 200/83 Z, 310/311, 310/319, 310/326, 310/328, 310/329, 310/333, 310/345, 310/348, 340/365 A
• US Class Current: 200/181
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: H03K 17/94 characterised by the way in which the control signals are generated
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

A pressure sensitive switch including a poly (vinylidene fluoride) (PVF₂) sheet arranged to be compressed and laterally outwardly distended under a load carrying on each major surface thereof contact means for receiving a signal generated by the sheet when compressed and distended two thick blocks of solid elastomeric material between which is sandwiched the sheet, and means for compressing and laterally outwardly distending both blocks by relative motion toward each other thereby in the absence of tension forces compressing and laterally outwardly distending the sheet sandwiched therebetween to generate the signal.

Claims

1. A pressure sensitive switch comprising a poly (vinylidene fluoride) (PVF₂) sheet arranged to be compressed and laterally outwardly distended under a load, contact means conductively connected to each major surface of said sheet for receiving a signal generated by said sheet when compressed and distended by the load, two thick blocks of solid elastomeric material between which is sandwiched said sheet, and means for compressing and laterally outwardly distending both blocks by relative motion toward each other and also in the absence of tension forces compressing and laterally outwardly distending said sheet sandwiched therebetween to generate said signal.

2. The pressure sensative switch as defined in claim 1 wherein at least one of said two thick blocks is electrically conductive.

3. The pressure sensitive switch as defined in claim 1 wherein said two thick blocks are each electrically conductive, and there is provided the sequential connection of one of said contact means, one of said electrically conductive thick blocks, the PVF₂ sheet, the other of said two electrically conductive thick blocks, the other of said contact means, and said compressing means, said compressing means being a manual push button for applying said load to compress and distend said blocks and sheet, and means interposed between said push button and the other of said contact means for preloading said sheet.

4. The pressure sensative switch as defined in claim 3 wherein said preloading means is a foamed elastomer.

5. A pressure sensitive switch comprising a poly (vinylidene fluoride) (PVF₂) sheet arranged to be compressed and laterally outwardly distended under a load, contact means connected to each major surface of said sheet for receiving a signal generated by said sheet when compressed and distended by the load, two thick blocks of solid elastomeric material between which is sandwiched said sheet, an electrical contact adjacent one of said thick blocks, means for preloading said sheet through said contact, means for compressing and laterally outwardly distending both blocks by relative motion toward each other and also in the absence of tension forces comprising and laterally outwardly distending said sheet sandwiched therebetween to generate said signal, and said preloading means being sandwiched between said one thick block and said compressing means.

6. The pressure sensitive switch as defined in claim 5 wherein said preloading means is a foamed elastomer.