| 摘要 |
PURPOSE:To obtain a DC signal held at its peak in an AC power supply cycle and to increase the freedom of design of a control circuit by arranging symmetrical half-wave rectifier by-pass circuits between the electrodes of a temperature sensitive substance. CONSTITUTION:A resistor 12 is connected to a commercial power supply 6 through electrodes 2, 4 coaxially and spirally wound through a heat sensitive material 3. The half-wave rectifier by-pass circuits 14, 15 are symmetrically connected between the electrodes 2, 4 through the resistor 13 and a terminal voltage VT, i.e. a temperature detecting signal, of a capacitor 16 in the half-wave rectifier by-pass circuit 15 on the positive cycle side and a temperature setting signal VS are inputted to a comparator 17 respectively. A control circuit 18 is actuated in accordance with the output of the comparator 17 to control current supply to a heater 19. The temperature detecting signal VT corresponds to the voltage dividing ratio of the resistor 12 to temperature-changed impedance between the electrodes 2, 4 of the heat sensitive substance and detects a peak voltage in a half-cycle. |
