| 摘要 |
PURPOSE:To obtain the driving circuit of a picture tube which prevents deterioration of frequency characteristic, by reducing the value of the collector resistance of a transistor which supplies a collector output to the cathode or the grid of the picture tube. CONSTITUTION:When both horizontal retrace pulse and vertical retrace pulse do not exist, the output voltage of a constant-voltage circuit 2 which is determined by a constant-voltage diode Dz, a resistance R9, and a volume VR is applied to the base of a transistor Q2. Therefore, a voltage which is lower than that of the emitter of the transistor Q2 is outputted and a low voltage is applied to a cathode Ca. When the horizontal retrace pulse or the vertical retrace pulse exists, a pulse of a relatively high level is inputted into the base of the transistor Q2 and, therefore, a high voltage is applied to the cathode Ca. Consequently, the collector loss of another transistor Q1 is reduced and the value of the collector resistance can be reduced. Thus deterioration of frequency characteristic due to a stray capacity is prevented. |
