| 摘要 |
PROBLEM TO BE SOLVED: To minimize a power shutoff frequency for eliminating the causes of discharge. SOLUTION: The electron beam device includes a high DC voltage-generating device 16, an electron gun 5, a means for detecting discharge from voltage between a filament 6 and an anode 8 of the electron gun 5, a sensing circuit for sensing whether discharge signals from the discharge detecting means are continued over a specified time or not, a trigger generating circuit 24 for generating trigger signals in accordance with the signals from the sensing circuit, a cutoff means 18a for cutting off a current between the filament 6 and the anode 8, and a normality resetting signal-generating circuit 20 for resetting a current cutoff condition between both electrodes into a non-cutoff condition. The current between both electrodes is set into the cutoff condition in accordance with the trigger signals from the trigger generating circuit 24, and the cutoff condition is reset into the non-cutoff condition with a delay in accordance with the trigger signals by the normality resetting signal-generating circuit 20. Signals generated from the sensing circuit during reset into the non-cutoff condition or the trigger signals are counted, and a delay time when the normality resetting signal-generating circuit 20 resets the cutoff condition into the non-cutoff condition is set depending on a counted value. COPYRIGHT: (C)2011,JPO&INPIT
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