GB1454805A - Pressure sensitive switch construction - Google Patents

Abstract

1454805 Retractive switches ESSEX INTERNATIONAL Inc 10 July 1974 [24 July 1973] 30513/74 Heading H1N A pressure sensitive switch assembly comprises a resilient, compressible, non-conductive member 1 having an opening 2 therethrough; electrical conductors 5, 6 spaced apart by said member 1, the compressibility of which enables relative movement of said conductors 5, 6 towards one another, bridging means 9 in said opening 2 to establish a conductive path between said conductors 5, 6 upon said relative movement thereof; and means 3 for limiting the compressive force to which means 9 may be subjected irrespective of the extent to which member 1 may be compressed. As shown the means 3 compresses a relatively incompressible annular washer of phenolic or other non-conductive rigid material. The bridging means 9 is preferably a cylinder of an elastomer with conductive particles dispersed therein to render it conductive when compressed or to render it conductive without compression, in which latter case the normal height of cylinder 9 is less than the uncompressed spacing between conductors 5 and 6. The member 1 preferably has a plurality of openings 2 each having an associated member 9 and annulus 3 and the assembly is encased in a sheath 10 of p.v.c. to form a mat switch. The conductors 5 and 6 are copper screens secured to member 1 by layers 7 and 8 of an adhesive which if not inherently conductive is omitted at the openings 2. Connections from leads 14 and 17 to screens 5 and 6 are effected via elastomeric annuli 13 and 16 of similar material to members 9, a rivet 21 maintaining them sufficiently compressed to be conductive.