PURPOSE: To allow to put a table plate fixedly on a Kotatu main body without being restricted its setting direction by a method wherein a circuit, which connects over the wireless with the variable resonance circuit of the table plate and controls the energizing to a heating element by detecting the state of resonance of said variable resonance circuit in regard to voltage, is provided in the Kotatu main body.
CONSTITUTION: The circuit, which controls the energizing the heating element 9 by detecting the state of resonance of the variable resonance circuit 10 equipped in the table plate 12 and operated by means of an operating unit, is provided in the Kotatu main body 11. When the oscillation frequency of a voltage controlling oscillation circuit 1 nears the resonance frequency f0, the impedance of a circuit 10 rises and the output of a detector 4 lowers. When the output of the detector 4 drops below the reference voltage VD, the output of a comparator 5 turns to be low level, resulting in discharging capacitors C in order to lower the oscillation frequency of the circuit 1. On the contrary, when the oscillation frequency lowers, the capacitors C are charged by reversing the operation as described above in order to raise the oscillation frequency of the circuit 1. Consequently, the voltage across the capacitors C is kept constant, resulting in allowing to keep the temperature in the Kotatu constant by means of a power controlling circuit 8 and the like.
IKEHARA TAKASHI
KURITA AKIRA
MIYAHARA TAKASHI
| JPS57188962A | 1982-11-20 |