Patent ID: 7952288
Filing Date: 2011-05-31
Classification: H01J

Abstract:
1. A power supply apparatus that supplies a predetermined DC voltage to an anode electrode, cathode electrode, helix electrode and collector electrode provided for an electron tube, comprising: a Zener diode connected between said helix electrode and said anode electrode for limiting a potential difference applied to said helix electrode and said anode electrode to within a Zener voltage; a photocoupler having a photodiode at an input end thereof and a phototransistor at an output end thereof for closing or opening a circuit between a cathode and an anode of said Zener diode; a first switch for supplying or cutting off a DC voltage for said photodiode; a capacitor to which said DC voltage that is to be supplied to said photodiode is applied; and a control unit that turns ON said first switch beforehand to apply a DC voltage to said photocoupler and said capacitor and turns OFF said first switch simultaneously with the application of a helix voltage that is to be supplied to said cathode electrode.