PURPOSE: To improve the converging speed in a transient response state without deteriorating the steady characteristic.
CONSTITUTION: The output of a voltage control type variable oscillator VCO 1 is supplied to a divider 2, and the division signal (comparison pulse) is supplied to a phase detector 3. At the same time, a prescribed reference pulse is supplied to the detector 3. The detection output of the detector 3 is supplied to the VCO 1 via a filter 4, and a phase locked oscillation signal is taken out of the reference pulse. The oscillation signal is supplied to a counter 5 from the VCO 1, and the count value of the counter 5 is supplied to a decoder 6 for production of a horizontal deflection signal. Furthermore the oscillation signal is supplied to a counter 7 from the VCO 1, and the count value of the counter 7 is supplied to a decoder 8 for production of a prescribed stepped signal. Then the stepped signal is taken out with timing of the reference pulse. A drive current source 9 of the detector 3 is controlled in response to the level of the stepped signal. Then the detection gain of the detector 3 is controlled under the control of the current source 9.
MIURA SATOSHI
UEJIMA ATSUSHI
