Multimedia television receiver

摘要

A pump-up circuit includes a first capacitor C1 connected to the power supply Vcc via a first change-over switch SW1 to the reference potential point or a second capacitor C2. The second capacitor C2 is charged by the voltage control circuit 45 under the control of the pump-up voltage control signal so that the capacitors C1 and C2 are charged respectively during the scanning period. Upon input of a NTSC signal, the change-over switch SW1 is connected to the reference potential point and the charging voltage of the first capacitor C1 is used as the pump-up voltage. Upon input of a signal having a short vertical flyback period such as the signal from personal computers, the total of the charging voltages at the first and second capacitors C1 and C2 is used as the pump-up voltage.