PURPOSE: To obtain the dynamic focus circuit automatically matching a phase of a horizontal parabolic voltage waveform with a phase of plural deflection frequencies.

CONSTITUTION: The circuit consists of a phase comparator 7, a low pass filter 8, a VCO 9 and a delay circuit 10. The circuit receives a horizontal FBP as an input signal and a horizontal parabolic waveform is generated from a signal of a prescribed preceding phase with respect to the output signal of the circuit. The phase is adjustable. An optimum focus is always obtained with respect to plural deflection frequencies and this circuit is optimum to a display device of multiscan type.