| 摘要 |
PURPOSE: A calibrator is provided to equalize the whole brightness of a screen by calibrating the event that the brightness of a central part gets darker compared to an edge of the screen after varying the width of vibration of a vertical/horizontal parabola signal input to a direct current control amplification unit. CONSTITUTION: When a beam current generated in a high voltage generation unit(11) is fed to a B/U control signal generation unit(12), an ABL(Auto Beam Limit) control unit(12-1) within the B/U control signal generation unit prevents the excessiveness of the beam current generated in the high voltage generation unit. Herein, When the beam current of which excessiveness is prevented is output and is fed to an amplification unit(12-2) within the B/U control signal generation unit, the amplification unit receives a brightness control signal and amplifies and outputs it to a voltage for driving a direct current amplification unit. When B/U control signal is input in the direct current control amplification unit, the direct current control amplification unit varies and outputs the width of vibration of the input vertical/horizontal parabola signal based on the variation of the brightness signal of the input B/U control signal. Then the brightness control unit(15) regulates the amount of an electronic beam emitted from a cathode and equally calibrates the whole screen brightness of a braan tube after calibrating the brightness of a central part.
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