| 摘要 |
PURPOSE:To always obtain an image of prescribed width against various horizontal deflection frequencies by keeping time length of a half cycle of a switching period constant, and lowering an output of a regulator as a horizontal deflection period increases. CONSTITUTION:An output pulse Vd2 of a monostable multivibrator 13 is triggered at the time point of a rise of an oscillation waveform VOSC and becomes that which has pulse width of a prescribed time Td2. Subsequently, a switch TR 18 is allowed to conduct by time length of Ton being a little longer by a storage time portion than the pulse width Td2 by the pulse Vd2 through a base resistance 15 being an exciting stage, an exciting transistor TR 16, and an exciting transformer 17. This pulse width Td2 is a prescribed value which is determined by a constant of the multivibrator 13, therefore, the time length Ton also becomes constant. As a result, a value of a DC power supply voltage E'b being an average value of a square wave VSW ascends, when a horizontal deflection frequency fh becomes high. On the other hand, the voltage E'b is E'b=Eb.(Ton/Th). When a deflecting coil current Iy' is derived from these relations, a virtual peak-to-peak value becomes constant, when the time Ton is constant. Therefore, the dimension of an image display part always becomes constant. |
