| 摘要 |
PURPOSE:To attain just focus even at a corner of a CRT display by providing a horizontal deflection circuit in addition to a focus voltage generating circuit so as to modulate a focus voltage in a parabolic wave without deteriorating the linearity of a horizontal deflection current. CONSTITUTION:A large current with excellent linearity is obtained at a horizontal deflection circuit 3 as a horizontal deflection current in a switching pulse generated from a horizontal output circuit 2, a resistor R4 is connected to a sawtooth wave generating circuit 40 in a high voltage generating circuit 4 and a sawtooth wave voltage is obtained across the resistor and the sawtooth wave voltage is fed to a parabolic wave voltage generating circuit 41. Then the generated parabolic wave voltage is fed to a focus voltage generating circuit 5 to give a parabolic wave voltage to a focus electrode B. Thus, the parabolic wave voltage for focus adjustment is generated without deteriorating the linearity of the horizontal deflection current and a picture with matched focus is obtained even at the corner. |
