Temperature control in which the control parameter is the degree of imperfection in the impedance matching
First Claim
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1. In a temperature regulator:
- a device having an electrical impedance which varies as the temperature of the device varies over a specified region of its temperature range,means for applying pulsating current to said device to heat the same, said means having an impedance which is mismatched with the impedance of said device over at least part of the range over which the impedance of said device varies as a result of temperature change, whereby as the temperature of said device varies over said region the extent of mismatch of the impedances also changes,said means further comprising means for producing a signal indicative of reflected power that varies as a function of the impedance mismatch, andcontrol means responsive to said signal for varying said pulsating current in order to regulate the temperature of said device.
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Abstract
A temperature control system is disclosed for controlling heating current to a heater having an impedance which varies substantially with temperature. The change in impedance of the heater changes the degree of mismatch between the power transmission system and the heater resulting in a change in the voltage which is reflected back to the power transmission system. The reflected voltage is monitored and its magnitude compared to a reference source and the power to the heater is controlled in response to this comparison.
54 Citations
21 Claims
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1. In a temperature regulator:
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a device having an electrical impedance which varies as the temperature of the device varies over a specified region of its temperature range, means for applying pulsating current to said device to heat the same, said means having an impedance which is mismatched with the impedance of said device over at least part of the range over which the impedance of said device varies as a result of temperature change, whereby as the temperature of said device varies over said region the extent of mismatch of the impedances also changes, said means further comprising means for producing a signal indicative of reflected power that varies as a function of the impedance mismatch, and control means responsive to said signal for varying said pulsating current in order to regulate the temperature of said device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. The method of controlling the temperature of a load comprising,
providing the load with an electrical component having an impedance that changes with the temperature of the load, feeding the load with alternating current and producing a signal created by any impedance mismatch at the load, and detecting said signal and varying the amplitude of said current in response to changes in the magnitude of said signal to thereby control the temperature of said load.
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19. A device having an electrical impedance which varies with variations in temperature of the device,
means for supplying pulsating current to said device to heat the same and comprising a source of radio frequency current, an impedance matching device between said source and said device for at least approximately matching the impedance of said device to said source, whereby there is a reflected voltage that has a magnitude dependent on the degree of mismatch, said means having an impedance which is mismatched with the impedance of said device over at least part of the range over which the impedance of said device varies, whereby as the temperature of said device changes the extent of mismatch of the impedances also changes, and control means being responsive to the magnitude of said reference voltage to at least reduce the current supplied by said source to the load in response to one amount of mismatch, said current being restored in response to another amount of mismatch, whereby the current to said device changes to control the temperature of said device.
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21. In a temperature control
a ferromagnetic element having a permeability above 100 when said element is well below its effective Curie temperature and a permeability of about unity near its effective Curie, and means for feeding said element with pulsating current, said first-named means producing a voltage that increases when the temperature of said element increases and approaches said effective Curie temperature, said first-named means including means for detecting when said voltage increases to a selected threshold and for at least reducing the magnitude of said current when said threshold is reached, with said current being restored to its former value when said element cools, whereby said current occurs in a series of pulses of a length and spacing that will hold the temperature of said element substantially constant.
Specification