| 摘要 |
A deflection switch (Q1) of a horizontal deflection circuit (250) is coupled to a retrace resonant circuit (100) that includes a horizontal deflection winding (LH) and a first retrace capacitance (C1). A flyback transformer primary winding (W1) is coupled to a junction terminal (collector of Q1) of the deflection switch (Q1) and the retrace resonant circuit. An East-West modulation current is generated by a bidirectional second switch (Q2) having a conduction time that is phase modulated during horizontal retrace at a vertical rate in a parabolic manner. The second switch (Q2) is coupled in series with the deflection switch (Q1) during the entire trace interval. To prevent an over-current condition when the current in the second switch (Q2) exceeds a predetrermined first level, the second switch (Q2) is turned off and interrupts the flow of current through the deflection switch (Q1). Additionally, a diode (D1) is coupled between an intermediate terminal of the transformer primary winding (W1) and a ]unction terminal of the deflection (Q1) and the second (Q2) switches for preventing an overvoltage condition from developing across the second switch (Q2). |
