Surface heating device

Claim 2

A package including a dispensable container containing a substance to be heated while in the container and thereafter to be removed from the container, a thin low voltage heating film having a surface pattern presenting a resistive electrical path between at least two terminals, said film being of metal foil which is integral with at least one unpatterned marginal portion of at least the same width as the pattern and which is folded over the pattern to constitute an impervious cover layer, the film also including a thin electrically insulating layer between the folded over portion and the pattern said film being incorporated in the package with the terminals accessible for connection to a supply without removing the substance from the container, the path between said film and the substance being of low thermal resistance and said surface pattern being so dimensioned that when connected to a supply at a predetermined voltage the difference between the heat dissipated into the substance in the container from any area of the surface of the heating film and the wattage supplied to said area is less than 4 watts per square inch of said area, and means including thermal insulation between the film and the external surface of the complete package insuring that when the film is energized more heat is dissipated into the substance than reaches the external surface of the complete package.

Claim 3

A container as set forth in claim 1 in which the heating film is contoured and located so that the unpatterned marginal portion forms an inner wall of the container, and the container includes a thermally insulating layer of stiff fibrous material on the outside of said film.

Claim 4

A package including a dispensable container containing a substance to be heated while in the container and thereafter to be removed from the container, a thin low voltage heating film having a surface pattern presenting a resistive electrical path in two sections with one terminal common to both sections and each section having another terminal so that there are three terminals in all, said film being incorporated in the package with the terminals accessible for connection to a supply without removing the substance from the container, said terminals beiNg relatively arranged in a staggered formation to enable single, series or parallel connection to be made merely by positioning a set of three contacts in relation to the terminals without change in the relative position among themselves of the three contacts, the path between said film and the substance being of low thermal resistance and said surface pattern being so dimensioned that when connected to a supply at a predetermined voltage the difference between the heat dissipated into the substance in the container from any area of the surface of the heating film and the wattage supplied to said area is less than 4 watts per square inch of said area, and means including thermal insulation between the film and the external surface of the complete package insuring that when the film is energized more heat is dissipated into the substance than reaches the external surface of the complete package.

Claim 5

A package including a dispensable container containing a substance to be heated while in the container and thereafter to be removed from the container, a thin low voltage heating film having a surface pattern presenting a resistive electrical path in two sections with one terminal common to both sections and each section having another terminal so that there are three terminals in all, said film being incorporated in the package with the terminals accessible for connection to a supply without removing the substance from the container, said terminals beiNg relatively arranged in a staggered formation to enable single, series or parallel connection to be made merely by positioning a set of three contacts in relation to the terminals without change in the relative position among themselves of the three contacts, the path between said film and the substance being of low thermal resistance and said surface pattern being so dimensioned that when connected to a supply at a predetermined voltage the difference between the heat dissipated into the substance in the container from any area of the surface of the heating film and the wattage supplied to said area is less than 4 watts per square inch of said area, and means including thermal insulation between the film and the external surface of the complete package insuring that when the film is energized more heat is dissipated into the substance than reaches the external surface of the complete package.

Claim 6

A package including a dispensable container containing a substance to be heated while in the container and thereafter to be removed from the container, a thin low-voltage heating film having a surface pattern presenting a resistive electrical path between at least two terminals, the surface pattern of said film including at least two large surface areas of thin metallic layers forming said terminals and also forming adjacent electrodes and a carbon film which extends over said electrodes and forms the electrical path between them, said film being incorporated in the package with the terminals accessible for connection to a supply without removing the substance from the container, the path between said film and the substance being of low-thermal resistance and said surface pattern being so dimensioned that when connected to a supply at a predetermined voltage the difference between the heat dissipated into the substance in the container from any area of the surface of the heating film and the wattage supplied to said area is less than 4 watts per square inch of said area, and means including thermal insulation between the film and the external surface of the complete package insuring that when the film is energized more heat is dissipated into the substance than reaches the external surface of the complete package.

Claim 7

A package including a dispensable container containing a substance to be heated while in the container and thereafter to be removed from the container, a thin low-voltage heating film having a surface pattern presenting a resistive electrical path between at least two terminals, the surface pattern of said film including at least two large surface areas of thin metallic layers forming said terminals and also forming adjacent electrodes and a carbon film which extends over said electrodes and forms the electrical path between them, said film being incorporated in the package with the terminals accessible for connection to a supply without removing the substance from the container, the path between said film and the substance being of low-thermal resistance and said surface pattern being so dimensioned that when connected to a supply at a predetermined voltage the difference between the heat dissipated into the substance in the container from any area of the surface of the heating film and the wattage supplied to said area is less than 4 watts per square inch of said area, and means including thermal insulation between the film and the external surface of the complete package insuring that when the film is energized more heat is dissipated into the substance than reaches the external surface of the complete package.