| 摘要 |
PURPOSE:To reduce blur of a pattern even when a field period is changed by controlling a gain of a comparator means with a gain control means. CONSTITUTION:A discharge current I of a capacitor CO is controlled by a gain variable comparator circuit A5, reference voltage sources Vr, Vx, a capacitor Cx and a voltage-current converter A4. The gain variable comparator circuit A5 compares two inputs for a pulse period of a vertical amplitude comparison pulse and to amplify the comparison error at a gain based on a gain switching control signal and outputs the result. An output terminal of the gain variable comparator circuit A5 is connected to a reference potential point via the capacitor Cx and connected to one input terminal of the voltage-current converter A4. A reference voltage Vx is given to the other input terminal of the voltage- current converter A4 and the voltage-current converter A4 supplies a current based on the difference of the two inputs as the discharge current I. |
