| 摘要 |
PROBLEM TO BE SOLVED: To improve the sharpness by multiplying a signal changing depending on a position of an electron beam with a correction signal to modulate a beam scan speed and supplying the product to a deflection magnetic field generator. SOLUTION: A scanning speed modulation current generating circuit receives a luminance signal Y to produce a scanning speed modulation signal SVM-OUT, which increases or decreases a beam deflection magnetic field consisting of horizontal and vertical components by horizontal and vertical deflection windings Ly, Lv via a coil L1. Since a horizontal/vertical displacement of a beam by a unit angle of beam deflection differs between a middle part and an end of a screen, a modulation multiplier 31 is used to compensate the difference, which multiplies a modulation control signal 31a with a signal 30a to generate an SVM level indication signal 31b. A value of a modulation control signal 31a is calculated on the basis of a position of a beam on the screen of a CRT 36 and the signal 31a is set so that it has a constant value in the middle area of the screen and the value is linearly being decreased toward the peripheral part.
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