Patent ID: 7709770

Claim:
A heating device for surface heating of a body so as to maintain a required temperature of the body, the heating device comprising an electrical heating element structure and a power source for supplying a required voltage to the heating element structure, wherein said heating element structure is constructed to enable its operation with a desired temperature of an outer surface of the heating element structure to provide as low as desired temperature gradient between the outer surface temperature of the heating element structure and the required body temperature, and substantially uniform heat transfer towards the surface of the body, the heating element structure comprising: first and second separate elements arranged in a spaced-apart parallel relationship along their surfaces one on top of the other with an electrical insulator between them, wherein the first element is connected to the power source when the device is put in operation and serves as a heater, and the second element, which is to be located closer to the heated body, is made of a different material of a specific resistivity lower than that of the first element and has a surface area larger than that of the first element, thus operating as a heat-diffuser providing substantially uniform distribution and transfer to the body of heat created by the first element when in operation, each of said first and second elements being configured to have a predetermined length and width such that the temperature gradient between the temperature of the outer surface of the heating element structure when in operation and said required temperature of the heated body is substantially low, at least the first element being configured as a strip arranged for compensating a magnetic field created by the first conductive element when in operation.