Abstract: A driver circuit for a high frequency switching circuit such as a converter for a gas discharge lamp includes a resonant circuit which transfers energy from the parasitic input capacitance of one or more power switching devices during switching of the latter. The energy transfer prevents dissipation of the capacative energy in the driver circuit which may otherwise destroy one or more components of the driver circuit. The resonant circuit includes a discrete inductor in the driver circuit. Preferably, one or more discrete capacitors are also included within the driver circuit to maintain resonance at a given frequency regardless parasitic capacitance variation.

Abstract: An electronic ballast that includes a DC power source and a transformer comprising first, second and third windings. The first, second and third windings being inductively coupled, and the third winding is connected in parallel with a load. The ballast also includes first and second circuit pathways connected in parallel. The first circuit pathway comprises a first switch connected in series with the first winding, and the second circuit pathway comprises the second winding connected in series with a second switch. The DC power source is connected in parallel with the first and second circuit paths to provide an input voltage source. A capacitor connects the point between the first switch and first winding of the first circuit pathway with the point between the second switch and the second winding of the second circuit pathway.

Abstract: An electronic ballast that includes a DC power source and a transformer comprising first, second and third windings. The first, second and third windings being inductively coupled, and the third winding is connected in parallel with a load. The ballast also includes first and second circuit pathways connected in parallel. The first circuit pathway comprises a first switch connected in series with the first winding, and the second circuit pathway comprises the second winding connected in series with a second switch. The DC power source is connected in parallel with the first and second circuit paths to provide an input voltage source. A capacitor connects the point between the first switch and first winding of the first circuit pathway with the point between the second switch and the second winding of the second circuit pathway.

Abstract: A monitor deflection circuit includes a bipolar power transistor for applying power from a high voltage supply to a horizontal deflection coil. The monitor deflection circuit further includes a base drive circuit for selectively turning the bipolar power transistor on and off. The base drive circuit includes a flyback transformer having a primary winding and a secondary winding coupled to the base of the bipolar power transistor, a voltage source coupled to one end of the primary winding, and a drive switch coupling the other end of the primary winding to ground. The base driver circuit further includes a constant current circuit coupled between the voltage source and the primary winding of the flyback transformer for controlling a base current of the bipolar power transistor before the bipolar power transistor conducts.

Abstract: A voltage boost power converter circuit, having an input inductor, active switch, and a transformer having primary, secondary and auxiliary windings. A clamping capacitor and a first passive switch are in series across the primary winding. The auxiliary winding and a second passive switch are in series, connected to the node between the clamping capacitor and first passive switch. The active switch is connected between ground the primary winding. A bulk capacitor forms a series loop including the active switch and primary winding. The method efficiently resets a the transformer, by transferring power to a load through the primary winding, and discharging a clamping capacitor through a separate inductively linked winding of the transformer during an ON state; and clamping the active switch voltage with the clamping capacitor, charging the clamping capacitor with a leakage inductance of the transformer, and charging the bulk capacitor during an OFF state.

Abstract: Power factor is improved, and line current total harmonic distortion (THD) is reduced by feeding high frequency current from a voltage source directly to one of the AC-side rectifier terminals. The low frequency power source presents a low value capacitive source impedance to the AC-side rectifier terminals. A resonant load lamp circuit is connected between an inverter output node and one of the DC outputs of the input rectifier circuit. A high frequency capacitor is connected between an AC-side terminal of the input rectifier circuit and a voltage source such as one of the lamp terminals or the inverter output. If the connection is to the inverter output, preferably a second high frequency capacitor is connected from the other of the AC-side terminals to the inverter output.

Abstract: An electronic ballast having an RF resonant inverter and RF feedback from the inverter which provides power factor correction. The feedback is provided by a capacitor coupled between an RF resonant tank circuit of the resonant inverter and a low frequency point in the ballast. Such feedback integrates the power factor correction stage with the RF resonant inverter stage and eliminates a switch and its controller. Electronic ballasts operating at RF frequencies require fast switching isolation diodes. Ultra-fast silicon diodes with very short recovery times, which have been used as such isolation diodes, are sensitive to ambient temperature and deteriorate the power factor and total line current harmonic distortion of the ballast. Use of either GaAs or silicon carbide isolation diodes instead of silicon diodes provides the ballast with a high power factor and a low total harmonic distortion.

Abstract: Circulating current through a resonant tank circuit and inverter switches is reduced by feeding high frequency current back through a line inductor. A resonant load circuit is connected between an inverter output node and one of the terminals of the input rectifier circuit. A high frequency capacitor has one terminal connected to an AC-side terminal of the input rectifier circuit. The line inductor and the high frequency capacitor have values selected such that instantaneous high frequency capacitor current flow into that AC-side terminal has a greater magnitude than and polarity opposite to current through the line inductor into that AC-side terminal during a portion of every cycle of the high frequency voltage.

Abstract: A gas discharge lamp driving circuit reduces input power at start-up mode through the utilization of input power diodes and stress capacitors in parallel therewith. The circuit includes a blocking filter for filtering an AC voltage signal, and a rectifier for rectifying the signal into a DC voltage. A smoothing capacitor smooths the voltage, and an inverter, having switches, converts the DC voltage into a high frequency AC voltage. A control circuit controls the switches of the inverter to turn on and off in a feedback manner. A resonant tank is connected to the inverter, and includes a resonant capacitor and a resonant inductor. A discharge lamp is connected to the resonant tank, in parallel with the resonant capacitor. A modulation capacitor is provided for reducing a distortion of the input current to the resonant circuit.

Abstract: An improved discharge lamp driving circuit of a charge-pump type capable of suppressing a ripple in an envelop of a lamp current at the time of dimming the lamp or at a low environmental temperature. The circuit includes an inverter having switching elements Q1 and Q2 for converting a voltage across a smoothing capacitor Ce into a high frequency power which is applied through a resonant circuit to the discharge lamp Ld. A capacitor Cin is connected to one end of the resonant circuit to vary a DC voltage of the output of the rectifier in accordance with a varying instantaneous value of the high frequency current or voltage appearing in the resonant circuit. A control circuit is provided to give a control signal for alternately turning on and off the switching elements Q1 and Q2.

Abstract: A high frequency HID ballast includes an inverter for operating the HID lamp at high frequency and an arc instability controller which detects and adjusts the operating frequency of the inverter to avoid acoustic resonance of the discharge arc. The ballast ensures that the power delivered to the lamp remains substantially constant despite variations in the gain of the inverter which occur with changes in the operating frequency. Power control is accomplished by sensing lamp power and controlling a boost converter to vary the bus voltage feeding the inverter. The boost converter is also controlled during lamp ignition, when the load provided by the HID lamp is low, to clamp the bus voltage at a predetermined level. The ballast employs universal techniques suitable for operating HID lamps of different types, wattages and manufacturers despite the occurrence of acoustic resonance/arc instabilities among these lamps over a fairly broad frequency range.