| 摘要 |
PURPOSE:To realize the temperature control with high safety by comparing the resistance value of a temperature measurement resistance line with the impedance value of a heat-sensitive layer and outputting a temperature control signal to a power control element when the difference obtained from said comparison is kept within a prescribed range. CONSTITUTION:A comparison means 8 has input of the output signal of a resistance measuring circuit 6 and the signal of an impedance measuring circuit 7 and outputs a temperature control signal to a power control element 3 when the impedance value of a heat-sensitive layer 4 for a resistance of a temperature measuring resistance line 5. is kept at a level between the prescribed upper and lower limit values. Thus a heating line 2 is controlled. In case the characteristics of the layer 4 are deteriorated by some reason and the resistance value of the line 5 gets out of the upper or lower limit value against the impedance of the layer 4, no output is given to the element 3. Then the energization of the line 2 is stopped. Thus no fear is produced for burns or fires and the high safety is secured with a temperature controller.
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