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US 5,695,859 AGranted
Pressure activated switching device
OwnerLester E. Burgessinventor
Life of this patent
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Abstract
A pressure sensitive sparkless switching device includes a layer of piezoresistive cellular polymer foam, at least two conductive layers, and an insulative spacer element having at least one opening. When pressure is applied to the device the piezoresistive foam disposes itself through the opening of the spacer element and makes electrical contact between the conductive layers. The resistance of the piezoresistive foam varies with the amount of pressure applied to provide an analog as well as on-off function. The device may also provide multiple switching, and shear detection capabilities.
Claims18
A pressure actuated switching apparatus, which comprises:
- a) first and second conductive layers;
- b) a layer of compressible piezoresistive material disposed between said first and second conductive layers;
- c) at least one insulative spacer element positioned between said piezoresistive material and at least one of said first and second conductive layers, said spacer element possessing a plurality of openings;
- wherein in response to a predetermined amount of force applied thereto said compressible piezoresistive material disposes itself through at least some of said openings of said spacer element to make electrical contact with said second conductive layer, and wherein said piezoresistive material includes an expanded polymeric foam having a plurality of voids dispersed in a polymeric matrix, the matrix having a mixture of conductive particles and conductive fiber incorporated therein.
1 more element
Dependencies are inferred from the claim text.