| 摘要 |
PURPOSE:To avoid the thermal overshoot which is caused by the rise control, by supplying the voltage corresponding to the temperature of a liquid plus the rise electric power corresponding to the reference voltage and the differential voltage to a heater for a certain period of time. CONSTITUTION:The output voltage of temperature sensors 7 and 8 is compared with the reference voltage corresponding to a target temperature given from a reference setting voltage source 11 through differential amplifiers 9 and 10. The output of the amplifier 9 is supplied to a voltage-current converter 12. When the temperature of a liquid is lower than the target level, the output voltage of the amplifier 9 is comparatively low. Thus the output current of the converter 12 is supplied to a heater 16 with a comparatively low rise current only for the working time of a timer 13. On the other hand, the control current given from a current control circuit 14 is supplied to the heater via a reverse current preventing diode 15. In case when the temperature of the liquid is lowered less, the output voltage of the amplifier 9 increases. As a result, the output of the converter 12 increases, and the heater current superposed on the current supplied from the circuit 14 is increased. |
