PROBLEM TO BE SOLVED: To prevent remarkable transient phenomenon of focus voltage after finish of an AKB measurement period by applying a second input signal to a second input of an amplifier to control focus voltage in the AKB measurement period.;SOLUTION: A first semiconductor switch responds to a periodical control signal in an AKB measurement period and coupled to a signal path of a focus voltage compensation input signal. A second semiconductor switch responds to a control signal so that a second input signal is applied to a second input of an amplifier out of the AKB measurement period. That is, the current of a transistor Q15 providing a current path to a transistor Q20 through a resistor R27 reduces an output voltage at a terminal 97a in the AKB measurement period. The transistor Q20 drops voltage applied to a resistor R1. A dynamic focus voltage at the terminal 97a in the AKB measurement period is set to a level being equal to a peak of sum of horizontal and vertical radiation components.;COPYRIGHT: (C)2000,JPO
展开▼
