| 摘要 |
PROBLEM TO BE SOLVED: To maintain a proper display resolution capability by controlling a change in convergence due to a thermal change in a heater and electric charging on an inner wall of a neck part or the like. SOLUTION: Integration circuits 210, 220 integrate a heater voltage applied to a heater 134 by a heater power supply 170 and have a time constant corresponding to thermal fluctuation in a 1st and 2nd grid electrodes. An integration circuit 230 integrates an anode current detected by an anode current detection circuit 180 and has a time constant corresponding to a fluctuation in an electron beam amount. A convergence correction circuit 200 applies a convergence correction voltage to a correction electrode in an electron gun 130 on the basis of integration outputs from the integration circuits 210, 220, 230, supplies a convergence correction current to a correction coil in a deflection yoke 150 so as to correct the convergence on the basis of a change in the applied voltage and a change in the anode current to the heater 134.
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