PURPOSE: To cut off surely the connection to a heating source when an outer lid is closed without an inner pan by stopping the current supply to the heating source when the reference of a temperature sensor circuit including a negative temp. coefficient thermistor exceeds a second reference.
CONSTITUTION: Voltage divided by a negative temp. coefficient thermistor 6 and a resistor 14 is inputted to a voltage comparator 13 to be compared with comparison voltage. When terminals P1-P3 are set to low level, temperature other than the ordinary use temperature set by a resistor 17 for forming a second reference is detected by a voltage comparator 13. The resistance value of the resistor 17 is set large and the temperature is set for example to -20°C outside the range of ordinary use temperature. If an inner pan 4 is removed from a main body 2 and a temperature sensor unit 5 is moved upward by the urging force of a spring 7, a switch 8 is opened. Then, the output of the voltage comparator 13 is set to high level to indicate the absence of the pan, buzz a buzzer 25 for a certain time, prohibit a drive circuit and stop the current supply to a heater.
NIIYAMA TORU
SATO SHINICHI
| JPS6331620A | 1988-02-10 | |||
| JPS59146616A | 1984-08-22 | |||
| JP56088430B |