Electric heater having laminated structure

Claim 1

A LAMINATED STRUCTURE USEFUL AS AN ELECTRIC HEATING ELEMENT WHICH COMPRISES A. A BOTTOM LAYER COMPOSED OF A FILM OF ELECTRICALLY INSULATING POLYMERIC MATERIAL, B. IN SUPERPOSED ADHERENT RELATION WITH LAYER (A), A DISCONTINUOUS LAYER OF ELECTRICALLY CONDUCTIVE ELASTOMERIC MATERIAL CONTAINING ELECTRICALLY CONDUCTIVE CARBON BLACK DISPERSED IN A FLUOROCARBON ELASTOMER, SAID DISCONTINUOUS LAYER COVERING SUBSTANTIALLY ALL OF LAYER(A) EXCEPT FOR SPACING AREAS WHICH OCCUR AT PREDETERMINED INTERVALS ALONG THE LENGTH OF LAYER(A), SAID SPACING AREAS EXTENDING ACROSS THE WIDTH OF LAYER(A) WHEREBY LAYER(B) IS DERIVED INTO A SERIES OF COATED AREAS OF PREDETERMINED LENGTH, LAYER(B) HAVING A THICKNESS OF ABOUT 0.05-0.45 MIL, C. AT LEAST TWO SPACED-APART CONDUCTOR WIRES IN INTIMATE CONTACT WITH LAYER(B) AND EXTENDING SUBSTANTIALLY THE ENTIRE LENGTH OF THE LAMINATED STRUCTURE, AND BONDED WITHIN THE STRUCTURE BETWEEN LAYERS(A) AND (D), AND D. A TOP LAYER COMPOSED OF A FILM OF ELECTRICALLY INSULATING POLYMERIC MATERIAL IN SUPERPOSED ADHERENT CONTACT WITH LAYER(B) AND SAID SPACING AREAS OF LAYER(A), EACH OF SAID LAYERS(A) AND (D) BEING A FILM OF A HIGHLY FLEXIBLE NON-ELASTOMERIC DURABLE PLASTIC MATERIAL HAVING A THICKNESS OF ABOUT 0.5-15 MILS, AND SAID COATED AREAS OF LAYER(B) MEASURING ABOUT 11-15 INCHES, AND SAID SPACING AREAS MEASURING ABOUT 1-5 INCHES IN THE DIRECTION PARALLEL WITH THE CONDUCTOR WIRES.