| 摘要 |
PURPOSE:To always reproduce a video with high quality by cutting the electron beam of a picture tube equivalent to an excessive overscan component by generating a blanking signal in accordance with the aspect ratio of a video signal. CONSTITUTION:When the video signal with aspect ratio of 4:3 is inputted to a television receiver with aspect ratio of screen is 16:9, the output of a first comparator 6 goes to an H level during a period over the first reference voltage V1 of the terminal voltages of a feedback resistor 4, and a pulse which sets the period as a vertical blanking signal period newly is outputted. Similarly, the output of a second comparator 9 goes to the H level in the period over the second reference voltage V2 of the terminal voltages of the feedback resistor 4, and a pulse which sets the period as the vertical blanking signal period newly is outputted. The output of a third comparator 12 goes to the H level only in the pump-up period of the output voltage of a vertical output amplifier 2, and a pulse equivalent to an original vertical blanking signal period can be outputted. |
