A parallel scanning circuit outputs a parallel scanning signal for making forward
and backward scanning lines parallel. A vertical correlation detection circuit
detects a portion where the change in luminance in the vertical direction exceeds
a predetermined value on the basis of a luminance signal, and outputs a movement
control signal representing the distance of movement on the screen of the scanning
line. A retrace period reversion circuit reverses the lime axis of the movement
control signal in a retrace period. A clamping circuit clamps the movement control
signal to a predetermined DC voltage at the timing of horizontal synchronizing
signal. A synthesizing circuit synthesizes the parallel scanning signal and the
movement control signal, and feeds a synthesized signal as a vertical velocity
modulation signal to a vertical velocity modulation coil.
