| 摘要 |
PURPOSE:To automatically compensate the fluctuation of vertical amplitude, by connecting a resistance having an optical conductivity to a vertical deflecting coil in parallel, and by changing the amount of light of the light source which is optically coupled with the resistance in accordance with the variation of the beam current of the cathode-ray tube. CONSTITUTION:At a focus circuit consisting of an FBT, a focus volume R1, and resistances R2 and R3, a waveform having strong correlation with high-voltage variation is obtained at the intersecting point (a) of the resistances R2 and R3. The waveform of the voltage at the intersecting point (a) is supplied to the base of a transistor 8 through an amplifier 7, and then, added to a light emission diode 6. When the high voltage drops and the electric potential at the intersecting point (a) drops, the amount of electric current passing through the light emission diode 6 is increased and the resistance value of a CdS5 is reduced. Therefore, the electric current flowing into a vertical deflecting coil 2 is reduced and the extent of amplitude is compensated. |
