| 摘要 |
PURPOSE: A method for driving dynamic focus of an electron gun of a cathode ray tube is provided to prevent the life span of the electron gun from being reduced due to arc discharge among electrode pins of the electron gun. CONSTITUTION: A dynamic focus driving method is constructed in a manner that a static focus voltage is applied to the first focus electrode of an electron gun of a cathode ray tube and a dynamic focus voltage that changes periodically within a range higher than the static focus voltage is applied to the second focus electrode of the electron gun, to allow an electron beam emitted from the electron gun to become vertically long shape. The dynamic focus signal has linearly symmetrical parabolic shape, being synchronized with the horizontal deflection signal of the cathode ray tube. The dynamic focus signal is clamped in a region corresponding to blanking time of the cathode ray tube. The clamped dynamic focus signal is amplified with a predetermined amplification level.
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