| 摘要 |
PROBLEM TO BE SOLVED: To efficiently vary the level of voltage supplied to the prescribed electrodes in an electron gun structure, without impressing voltage beyond the durable limit on a voltage divider resistor part built in a tube body. SOLUTION: This device is provided with a voltage divider resistor part (72) built in a tube body 51, and supplied with anode voltage supplied to an inner surface conductive layer 57, then supplying the voltage obtained according to the anode voltage to a convergence electrode ECO in an electron gun structure 59, and a variable resistance part (80) built in the tube body 51 to be connected to the electron gun structure 59 or the voltage divider resistor part (72), and varying the resistance according to the light irradiated from the outside of the tube body 51, to vary the level of voltage supplied to the convergence electrode ECO.
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