| 摘要 |
PROBLEM TO BE SOLVED: To provide a power source for an FEG equipped with an automatic control so as to transmit control signals only when operation conditions of the FEG are changed, and not to transmit same when the operation conditions are unchanged. SOLUTION: With a power source for the field emission electron gun provided with a drawer power source generating drawer voltage to impress on a drawer electrode, a control circuit generating control signals for setting the drawer voltage, a latch circuit for latching the control signals, and a control signal controlling circuit, a means for judging presence of a new control signal within a given time is provided, whereby, while there is a setting of a new signal within the given time, the control signal is transferred to the latch circuit with the control signal controlling circuit in a conductive state, and while there is none, the control signal controlling circuit is interrupted, and the field emission electron gun is started with the control signal latched in the latch circuit.
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