| 摘要 |
PURPOSE:To display a sharp picture with high S/N and excellent white balance by modulating a voltage fed to a beam extraction electrode for each pulse period of a pulse width modulation signal so as to apply inverse gamma correction to a video signal indirectly. CONSTITUTION:A voltage Vgamma of a connecting point between resistors 47, 48 is set to a midpoint between a high level and a low level of an input pulse to input terminals 49, 50 in a circuit applying the voltage to the beam extraction electrode. Then during the period (period of PW3) when the input pulse is at a low level, current I1 of a current source 51 all flows to a transistor(TR) 46 and does not flow to TRs 53, 54, then a voltage with the highest level is outputted. While a pulse having a width corresponding to the PW1 is at a high level, the current I1 flows to the TR 54 and a voltage drop is caused across the resistors 58, 57, and the voltage at the lowest level is outputted and a pulse with the width corresponding to the PW2 is at a high level then the output voltage reaches an intermediate level. Thus, the video signal is subjected indirectly inverse gamma correction and a sharp picture with excellent S/N is displayed with well white balance. |
