Resistance element

Claim 1

AN ELECTRICAL RESISTOR ELEMENT COMPRISING A RESISTOR PROVIDED WITH CONDUCTIVE CONNECTING TERMINALS FOR FORMING PORTIONS OF AN ELECTRICAL CIRCUIT, SAID RESISTOR COMPRISING FINELY DIVIDED CONDUCTIVE PARTICLES DISPERSED IN A MATRIX OF A RELATIVELY NON-CONDUCTIVE PLASTIC, SAID PLASTIC HAVING A COEFFICIENT OF THERMAL EXPANSION AT LEAST THREE TIMES GREATER THAN THAT OF SAID CONDUCTIVE PARTICLES, SAID CONDUCTIVE PARTICLES BEING IN SUBSTANTIAL PARTICLE TO PARTICLE CONTACT, SAID RESISTOR CONTAINING SUFFICIENT CONDUCTIVE PARTICLES AMOUNTING FROM ABOUT 25% TO ABOUT 75% OF THE TOTAL VOLUME OF THE RESISTOR MATERIAL AND DISPERSED THROUGH SAID PLASTIC MATRIX SO THAT BELOW A CRITICAL TEMPERATURE LEVEL IMMEDIATE PARTICLE TO PARTICLE CONTACT EXISTS BETWEEN THE CONDUCTIVE PARTICLES, WHEREAS ABOVE SAID TEMPERATURE LEVEL AND WHILE THE RESISTOR REMAINS A SOLID, SAID CONTACT BETWEEN CONDUCTIVE PARTICLES IS SUBSTANTIALLY BROKEN DUE TO THE DIFFERENCES IN THERMAL COEFFICIENT OF EXPANSION BETWEEN SAID PARTICLES AND SAID NON-CONDUCTIVE MATRIX, SAID CRITICAL TEMPERATURE BEING SUBSTANTIALLY ABOVE ROOM TEMPERATURE AND BELOW THE TEMPERATURES OF MELTING AND OF SUBSTANTIAL DETERIORATION OF THE PLASTIC, SAID RESISTOR BEING CHARACTERIZED BY A RELATIVELY FLAT CURVE OF ELECTRICAL RESISTANCE VERSUS TEMPERATURE BELOW SAID CRITICAL TEMPERATURE LEVEL AND BY A SHARPLY RISING CURVE BEGINNING AT SAID CRITICAL TEMPERATURE LEVEL, SAID RESISTOR FURTHER BEING CHARACTERIZED BY AN INCREASE IN RESISTIVITY OF MORE THAN 250% OVER A TEMPERATURE RANGE OF 25*F. AT ABOUT SAID CRITICAL TEMPERATURE LEVEL.