| 摘要 |
PURPOSE: A vertical deflection circuit of a CRT is provided to operate the vertical deflection circuit through pulse width modulation to improve linearity. CONSTITUTION: A vertical deflection circuit of a CRT includes a saw tooth digital data generator(410), the first and second pulse width modulation signal generators(420,450), a delayed locked loop(430), an S/C correction waveform data generator(440), and a vertical deflection signal output unit(460). The saw tooth digital data generator generates saw tooth digital data that is reset for every one period of a vertical synchronous signal and increased by 1 for one period of a system clock. The first pulse width modulation signal generator outputs a pulse width modulation signal responding to a variation in upper digital data of the saw tooth digital data. The delay locked loop outputs a saw tooth modulation signal obtained by extending the pulse width modulation signal. The S/C correction waveform data generator outputs S/C correction digital data. The second pulse width modulation signal generator pulse-width-modulates the S/C correction digital data to output an S/C correction modulation signal. The vertical deflection signal output unit adds up a value obtained by integrating the saw tooth modulation signal and a value obtained by integrating the S/C correction modulation signal in a predetermined ratio to output a vertical deflection output signal.
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