| 摘要 |
PURPOSE:To eliminate defect such as the destruction of a diode and to adjust easily the pre-heating power, by connecting a constant voltage diode and a heater in series between AC power terminals, and connecting a switch and the constant voltage diode in parallel. CONSTITUTION:The constant voltage diode 1 and the heater 3 are connected in series between the AC power supply terminals and the switch 2 and the constant voltage diode 1 are connected in parallel. The heater is heated with a normal half-wave waveform at a positive phase when a terminal 4 is positive and a current flows only when the voltage exceeds a Zener voltage VZ of the constant voltage diode at a negative phase when a terminal 5 is positive, then the waveform as shown in figure is obtained, and the pre-heating power is controlled to the optimum value by specifying the Zener voltage VZ. |
