PURPOSE: To correct a distortion of a white pattern part on the picture of a TV receiver by connecting the pulse of a fly-back transformer to a capacitor of a horizontal oscillating circuit which includes a resistance and the capacitor and constitutes a CR oscillator.

CONSTITUTION: A pulse 34 of a fly-back transformer FBT is integrated by a resistance 30 and a capacitor 27 and is supplied to a horizontal AFC circuit H through a capacitor 26. The circuit H detects a phase difference between the FBT pulse 34 and a horizontal synchronizing signal as a voltage, and this voltage is converted to a DC by a filter circuit F and is connected to a horizontal oscillating capacitor 28 through a resistance 35. A horizontal oscillating circuit S includes a resistance 32 and the capacitor 28 to constitute the CR oscillator and outputs this DC voltage to a terminal 23. The variance of the FBT pulse in white pattern part is detected by a differentiating circuit 25, and constans of a resistance 31 and a capacitor 29 are so selected that the distortion due to the variance of the DC level of a deflecting current is corrected, and the current flowed to the oscillating capacitor 28 is discharged or charged to eliminated a synthesized tortuosity.