| 摘要 |
<p>PURPOSE:To ensure the control for a load having a small allowable power rate value, by connecting a switching element in series to a heater element to control the state of conduction and providing a driving means to control the conduction or non-conduction of said switching element. CONSTITUTION:A switching element is connected is series to a heater element to control the state of conduction, and a driving means is added to control the conduction or non-conduction of the switching element. That is, a commercial power supply 11 is applied to a series circuit to a heater element 13 and a triac 15 which functions as a switching element as well as to a full-wave rectifying circuit 17. Thus the full-wave rectifying voltage er is connected to a reverse input terminal of a comparator 21, and at the same time the comparison reference voltage Er1 is supplied to a non-reverse input terminal of the comparator 21. Then a series circuit of a thermistor 23 and a variable resistor is connected between a plus voltage source +V1 and an earth, and the temperature detecting voltage es is supplied to a comparator 29 from a common joint 27 between the source +V and the earth. Then a zero voltage output signal 31 and a temperature detecting signal 33 are supplied to an AND gate 35, and an AND output signal 37 of the gate 35 is supplied to a central processor CPU, an AND gate 41, etc.</p> |
