| 摘要 |
PURPOSE:To attain the satisfactory control of temperatures by securing the even effect of the ambient temperature change over the set temperatures. CONSTITUTION:When the ambient temperature of a thermistor 27 rises up, the impedance of the thermistor 27 has a drop. Thus the voltage divided by the thermistor 27 and a resistance 28 increases. Then a transistor TR33 is turned on more easily; while a thyristor 13 is turned off more easily respectively. As a result, the temperature is corrected toward a lower level. When the ambient temperature of the thermistor 27 drops, the resistance level of the thermistor 27 rises up. Therefore the TR33 and the thyristor 13 are turned off and on more easily respectively. Thus the temperature is corrected toward a higher level. The both-terminal voltge of resistances 25 and 26 can be divided in a fixed ratio since a series circuit of the resistance 28 and the thermistor 27 is connected in parallel to a series circuit of a variable resistance 25 and a resistance 26. Thus an even correction is secured by the thermistor 27 regardless of the value of the resistance 25. |
