Patent ID: 6815039
Filing Date: 2004-11-09
Classification: H01B,H01C,Y10T

Abstract:
A conductive plastic resistance element in a variable resistor having a wiper for movably contacting said resistance element to vary the resistance of the variable resistor, the resistance element comprising:a substrate; a carbon and plastic resistive matrix disposed as a layer on said substrate and having a layer thickness, said carbon being a current carrying phase of the matrix wherein a higher percentage of carbon relative to the percentage of plastic in the carbon and plastic resistive matrix produces a lower resistance and a lower percentage of carbon relative to the percentage of plastic in the carbon and plastic resistive matrix produces a higher resistance; and particles of conductive material no larger than about 6 microns formed in situ and embedded in a surface of said layer of resistive matrix and exposed and projecting therefrom in sliding contact with the wiper contact of the variable resistor, said particles of conductive material forming a conductive phase at the surface operative to reduce a contact resistance between said resistive element and said wiper and being present in sufficient amount within a volume of said layer without excessively altering the resistive properties of said resistive matrix, said particles of conductive material projecting therefrom in sliding contact with the wiper contact of the variable resistor without degrading the wear properties of the resistive element.