| 摘要 |
PURPOSE: To obtain a clear image by employing constitution which enables inverseγcorrection and correcting respective colors as desired without exerting influence on a lighting position. CONSTITUTION: A decision circuit 56 decides the maximum number of pulses of a PWM circuit 51 in one PWM period in three stages and a switching circuit 52 performs switching among HPWM 53, MPWM 54, and LPMN 55. The circuit 53 holds a PWM voltage at a high potential and output the original number of pulses to a beam flow control electrode, the circuit 54 holds the voltage at an intermediate potential and outputs pulses 1.5 time as many as the original pulses, and the circuit 55 holds the voltage at a low potential and outputs pulses three times as many as the original pulses. Consequently, the relation between a pulse width amplitude modulated signal regarding the beam flow control electrode controlling the quantities of light emission of respective pixels and the quantity of electron beam irradiation on a screen can be set to desired relation, and consequently the inverseγcorrection of a video signal can be performed indirectly to prevent a sharp image which has its white balance well kept and a good SN from decreasing in peak illuminance.
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