| 摘要 |
PURPOSE:To attain the accurate modulation of a horizontal deflection amplitude by producing a sawtooth wave current which is flowed to a horizontal deflection coil so that the amplitude of said sawtooth wave current in response to the shape of a reference waveform and therefore compensating a phase delay due to the nonlinearity of a transistor or a circuit element. CONSTITUTION:A harmonic wave detecting circuit 8 delivers a voltage equivalent to the modulated wave parabolic component of the sawtooth wave current which is flowed to a horizontal deflection coil. An operational amplifier 9 serving as a comparator compares a reference voltage obtained from a waveform shaping circuit 7 with a detection voltage obtained from the circuit 8 and applies an output voltage V0 to a horizontal amplitude modulation circuit 5 for horizontal deflection coil current IH. Thus the voltage V0 of the amplifier 9 is set automatically so as to secure the coincidence at all times between a parabolic voltage W1 obtained in proportion to the parabolic modulated wave component of the current IH and the reference parabolic voltage W2 set previously. Thus the circuit 5 modulates the horizontal amplitude. |
