| 摘要 |
A color CRT includes a screen to effect display by being illuminated by electron beams and at least one grid for controlling a character of the display on the screen. A horizontal deflection coil is provided on the color CRT for horizontal deflection of the electron beams. A vertical deflection coil is provided on the color CRT for vertical deflection of the electron beams. A horizontal deflection circuit supplies a horizontal deflection current to the horizontal deflection coil. A vertical deflection circuit supplies a vertical deflection current to the vertical deflection coil. A horizontal parabolic waveform voltage generator generates a horizontal parabolic waveform voltage with the level thereof increasing for positions from the center to the edges of the screen according to the horizontal deflection current in synchronism to the horizontal deflection. A vertical parabolic waveform voltage generator generates a vertical parabolic waveform voltage with the level thereof increasing for positions from the center to the edges of the screen according to the horizontal deflection current in synchronism to the vertical deflection. A grid modulator supplies the horizontal and vertical parabolic waveform voltages in superimposition on a bias voltage to the grid.
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