| 摘要 |
PURPOSE:To facilitate the correction of a pulse voltage level caused in a winding by providing a saturable reactor to a part of a resonance circuit and a current adjusting circuit thereto in a focus circuit obtaining a focus voltage from a voltage induced in the winding of a flyback transformer via an LC resonance circuit. CONSTITUTION:In sliding a resistor variable terminal 9a toward the resistor 8 of the resistor 9 when a pulse voltage is generated in the secondary winding 1a of the flyback transformer 1, the base voltage of a transistor 11 rises. Then the collector current is increased and the current of the control winding 13 of the saturable reactor 40 is increased. Thus, the inductance of the load winding 12 of the reactor 40 is reduced and the pulse voltage level of the focus voltage terminal 4 is increased. In moving the slider toward the resistor 7 oppositely, the impedance of the load winding 12 is increased and the pulse voltage level of the terminal 4 is decreased. Thus, the inductance of the winding constituting the reactor 40 is changed continuously by the variable resistor 9 to obtain a proper focus voltage.
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