Power switch control circuit for television apparatus

A television deflection apparatus for generating, in accordance with an input voltage at a deflection rate, a deflection current in a deflection winding, comprising:

• a deflection winding;
• a deflection switch having a control electrode and a pair of current conducting electrodes, and coupled to said deflection winding for generating therein a trace current of a deflection current when said switch is conductive during a trace interval;
• a retrace capacitance coupled to said deflection winding to form a retrace resonant circuit during each retrace interval;
• a flyback transformer winding coupled to said switch and responsive to the voltage across said retrace capacitance for generating a deflection rate first voltage at a first polarity during said retrace interval and at an opposite polarity during said trace interval;
• an inductance coupled to said first voltage for generating a first control current in said inductance that is coupled to said control electrode during a portion of each trace interval to cause said switch to be conductive, wherein said first polarity of said first voltage causes said first control current to be progressively increasing throughout said trace interval and wherein said opposite polarity of said first voltage causes said first control current to decrease during said retrace interval;
• and
• means coupled to said control electrode and responsive to said input voltage at said deflection rate for generating a deflection rate second control current in said control electrode that causes said switch to be nonconductive.

A television switching apparatus for generating an output current in a power switch, comprising:

• a power switch having a control electrode and a pair of current conducting electrodes;
• a source of an input signal periodic at a switching rate;
• means responsive to said input signal for supplying, during both a start-up time and a following normal operation time, a first control current to said control electrode to cause said switch to be nonconductive between said current conducting electrodes during a first interval of each period of said input signal;
• an impedance coupled to said control electrode;
• and
• a resonant circuit coupled to said pair of current conducting electrodes and to said impedance for generating said output current periodic at said switching rate and for generating during said normal operation time an output voltage periodic at said switching rate that is applied to said impedance for supplying a second control current to said control electrode to cause said switch to be conductive between said current conducting electrodes during a second interval of each period of said input signal, wherein during said start-up time said first control current stores energy in said impedance in said first interval for supplying said second control current in said second interval to initiate the generation of said output voltage.

A television switching apparatus for switching an output current comprising:

• an inductive load circuit;
• a power transistor switch for switching said output current in said inductive load;
• a source of an input signal at an input rate;
• a control circuit for operating said switch at said input rate, said control circuit comprising:
• a source of reverse biasing voltage;
• a control switch coupled to said source and to the base of said power transistor switch;
• an inductance coupled to said control switch, said control switch being responsive to said input signal for coupling said reverse biasing voltage to said power transistor switch during a first interval of a given period of said input signal to turn off said power transistor switch, said reverse biasing voltage being applied to said inductance to generated inductive current therein during said first interval, wherein said control switch decouples said reverse biasing voltage from said power transistor switch and enables said inductive current to flow in said inductance in the same direction after said reverse biasing voltage is decoupled and into the base of said power transistor switch that turns on said power transistor after said first interval during a second interval of said given period.