| 摘要 |
PURPOSE:To obtain a blanking pulse with a pulse width having a fixed ratio against the period of a horizontal synchronizing signal by forming a parabolic wave from a flyback pulse and controlling the current of a current source. CONSTITUTION:When the flyback pulse of a horizontal period T is supplied to a terminal 36, a parabolic wave signal that is synchronized with the horizontal synchronizing signal is obtained at a connecting point where the coil 37a of a parabolic wave forming circuit 37 and a capacitor 37b are connected it is supplied, through a capacitor 38, to a connecting point where a diode 32 and a current source 33 are connected. And when potential at point (a) is higher than the potential at base (b) of a transistor 34, the diode 32 is cut off and current I2 that flows through the current source 33 is flowed from the capacitor 38. Also, When the potential at point (a) is lower than the potential at (b), the capacitor 38 is charged with current I2 - I2. Therefore, a pulse with a pulse width that is decided by the ratio of the current I1 of the current source 31 to the current I2 of the current source 33 is outputted from a terminal 45.
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