| 摘要 |
PURPOSE:To avoid an oscillating frequency from a horizontal oscillation circuit from sharing an audible tone frequency by providing an output holding circuit detecting an output of a 1st pulse generating circuit and an output of a power supply circuit and holding an output of an error amplifier circuit to a prescribed value so as to bring the oscillating frequency of the output of the horizontal oscillation circuit is a reference minimum frequency when the output of the 1st pulse generating circuit is a non signal and the output of the power supply circuit is a prescribed level or below. CONSTITUTION:With an input of a horizontal synchronizing signal whose frequency is lower than a reference horizontal frequency (15.78kHz) given, a primary voltage of a flyback transformer is ay with respect to the frequency ax as shown in figure and the voltage is lowered. An output of a monostable multivibrator circuit B does not reach a voltage to turn on a transistor(TR) Q2 after through resistors R7, R8 and a rectifier capacitor C3 and the TR Q2 is turned off. As a result, a current flows from a resistor R5 to a diode D2, a base potential of a TR Q1 rises, a charging current to a capacitor C1 in a horizontal oscillation circuit D is increased and a horizontal oscillation frequency of the horizontal oscillation circuit D rises up to the frequency regulated by the bias supplied through the resistor R5. |
