| 摘要 |
PURPOSE:To obtain a constant amplitude which is strong in the event of a high voltage variation, as well, by detecting whether an index signal exists or not in the inside and the outside of an index area of a moving index color picture tube, and controlling the vertical amplitude by this detecting signal. CONSTITUTION:An index signal Si which has been obtained through a Schmitt circuit is provided to a switching circuit 91, and also a signal Q85 which has been obtained by processing a vertical blanking pulse Pv, etc. is provided as a control signal. A signal Si whose period ti is varied corresponding to a scanning position of a scanning line is taken out as a signal in a period from a rise point T1 to a horizontal period T2, it becomes DC voltage S93 of a level corresponding to the period ti through a monostable multivibrator 92 and an integral network 93, and is provided as an amplitude control signal of a vertical deflecting circuit 100. In this way, the n-th scanning line is exactly controlled to a reference position, and the vertical amplitude is made constant even in the event of a high voltage variation, etc. |
