Abstract A multiple temperature autoregulating heater comprises a laminate of a conductive material, a first ferromagnetic layer on a surface of the conductive material and a second ferromagnetic layer insulated from the first layer. The layers have different Curie temperatures. A switching device is provided to connect one or the other of the layers to be energized from a constant current source. The device autoregulates in the region of the Curie temperature of the selected layer. The conductive material may be non-magnetic (copper) or a low resistivity ferromagnetic material having a Curie temperature well above the Curie temperatures of the autoregulating layers. In the latter case, a thin layer of copper or the like may be interposed between the surface and the conductive ferromagnetic material to further increase conductivity. The device may be provided with multiple ferromagnetic layers to provide multiple different autoregulating temperatures.
A multi-temperature autoregulating heater structure comprising: a conductive substrate providing at least a first surface, a first ferromagnetic layer on said first surface and electrically insulated therefrom, at least a second ferromagnetic layer electrically insulated from said first ferromagnetic layer and having a Curie temperature different from the Curie temperature of said first ferromagnetic layer, and means permitting of selective excitation of either one or the other of said ferromagnetic layers with alternating current.
Claim 2
Dependent Claim
74 words
A multi-temperature autoregulating heater structure comprising: a conductive substrate providing at least a first surface, a first ferromagnetic layer on said first surface and electrically insulated therefrom, at least a second ferromagnetic layer electrically insulated from said first ferromagnetic layer and having a Curie temperature different from the Curie temperature of said first ferromagnetic layer, and means permitting of selective excitation of either one or the other of said ferromagnetic layers with alternating current.
Claim 3
Dependent Claim
26 words
The apparatus according to claim 1 wherein said conductive substrate has an elongated dimension and said ferromagnetic layers surround said conductive substrate along its elongated dimension.
Claim 4
Dependent Claim
21 words
The apparatus according to claim 1 wherein said members are electrically insulated from another by a heat conducting, electrically insulating material.
Claim 5
Dependent Claim
18 words
The apparatus according to claim 1 wherein said members are insulated from one another by an air gap.
Claim 6
Dependent Claim
100 words
The apparatus according to claim 1 wherein said first surface is a continuous surface encompassing said substrate and wherein said first ferromagnetic layer has a surface surrounding said surface of said substrate and wherein said second ferromagnetic layer surrounds said surface of said first ferromagnetic layer, a source of a.c. constant current, and means connecting one terminal of said source to said conductive substrate and the other terminal of said source selectively to one or the other of said ferromagnetic layers, and means connecting said substrate and said layers together electrically at a location remote from connection of said structure.
Claim 7
Dependent Claim
14 words
The apparatus according to claim 5 wherein said substrate and said layers are rectangular.
Claim 8
Dependent Claim
14 words
The apparatus according to claim 5 wherein said substrate and said layers are cylindrical.
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