04695713 is referenced by 215 patents and cites 18 patents.

An autoregulating, electrically shielded heater employs a laminated structure having two magnetic alloy permeable materials of widely differing Curie point temperatures and preferably of differing resistivities. A constant current supply is connected across the laminate such that current flows in the laminae along parallel paths. Due to skin effect, the current is confined to a thin region of a first lamina which is located between the other lamina and the electrical return path. This first lamina has the lower Curie temperature and preferably the higher resistivity of the two laminae to produce heating proportional to I.sup.2 R.sub.1. When the Curie temperature of the first lamina is approached, the current spreads into the other lamina which may have a lower resistivity and higher Curie temperature and heating is obtained by I.sup.2 R.sub.2 where I.sup.2 is a constant due to the constant current source and preferably R.sub.2 <R.sub.1. Thus, power is reduced and temperature is maintained at or about the Curie temperature of the first layer. The high permeability of the second lamina prohibits the current from penetrating deeply into the second laminae whereby a low frequency power supply may be used without radiation of the electro-magnetic field.

Title
Autoregulating, electrically shielded heater
Application Number
430317
Publication Number
4695713
Application Date
October 19, 1983
Publication Date
September 22, 1987
Inventor
John F Krumme
Woodside
CA, US
Agent
Hall Myers & Rose
Assignee
Metcal
CA, US
IPC
H05B 3/10
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