Abstract: A ballast circuit for a plurality of serially connected, high pressure gas discharge lamps comprises an electromagnetic ballast arrangement receptive of an input power signal, providing an output ballast voltage for driving the plurality of lamps, and providing an open circuit ballast voltage when the lamps are disconnected from the arrangement. A first ignitor circuit is connected between the ballast arrangement and the first lamp, and produces at least one ignitor pulse of high voltage and high frequency compared to the open circuit ballast voltage, to initiate starting of the first lamp. A second ignitor circuit is connected between the first lamp and a second lamp so as to be supplied with current through the first lamp. The second circuit produces at least one ignitor pulse of high voltage and high frequency compared to the open circuit ballast voltage after the first lamp begins to start and drops substantially in impedance, to initiate starting of the second lamp.

Abstract: Disclosed is an integrated circuit for use in a ballast circuit for supplying a.c. current to a resonant load circuit incorporating a gas discharge lamp and a resonant inductance and capacitance. The integrated circuit comprises a d.c.-to-a.c. converter circuit comprising first and second switches serially connected between a bus pin, for connection to a bus conductor at a d.c. voltage, and a reference pin, for connection to a reference conductor. The switches are connected together at a node connected to a common pin through which the a.c. current flows, have respective control nodes connected to a control pin, and have respective reference nodes. The voltage between the control pin and an associated reference node determines the conduction state of the associated switch. A first embodiment also includes first and second resistors serially connected between the bus and reference pins, with their intermediate node connected to an intermediate pin.

Abstract: A power supply circuit for powering a load circuit comprises a load circuit and includes a converter circuit for inducing current in the load circuit. The converter circuit comprises first and second converter switches serially connected in the foregoing order between a bus conductor at a d.c. voltage and a reference conductor, and connected together at a common node through which the load current flows. The first and second converter switches each comprise respective interconnected control nodes and references connected together at the common node. The voltage between a control node and associated reference node determines the conduction state of the associated switch. A first node is coupled to the bus conductor, and a second node is coupled to the reference conductor. A bridge network is connected between the first and second nodes and has first and second input nodes on which respective first and second input signals are applied.

Abstract: A ballast circuit for a gas discharge lamp comprises a resonant load circuit including the lamp. A d.c.-to-a.c. converter circuit induces an a.c. current in the resonant load circuit. The converter circuit comprises first and second switches serially connected between a bus conductor at a d.c. voltage and a reference conductor, and being connected together at a common node through which the a.c. load current flows. The first and second switches each comprise a reference node and a control node, the voltage between such nodes determining the conduction state of the associated switch. The respective reference nodes of the first and second switches are interconnected at the common node. The respective control nodes of the first and second switches are interconnected. An inductance is connected between the control nodes and the common node. A starting pulse-supplying capacitance is connected in series with the inductance, between the control nodes and the common node.

Abstract: A gas discharge lamp ballast comprises a load circuit including circuitry for connection to a gas discharge lamp. A circuit supplies d.c. power from an a.c. voltage. A d.c.-to-a.c. converter circuit is coupled to the load circuit for inducing a.c. current therein. The converter circuit comprises first and second converter switches serially connected in the foregoing order between a bus node at a d.c. voltage and a reference node, and being connected together at a common node through which the a.c. load current flows. The first and second converter switches each have a control node and a reference node, the voltage between such nodes determining the conduction state of the associated switch. The respective control nodes of the first and second converter switches are interconnected. The respective reference nodes of the first and second converter switches are connected together at the common node.

Abstract: A high intensity discharge lamp comprises an elongated, main arc tube containing a gas fill. First and second in-leads are connected to first and second electrodes within the arc tube, with an arc gap being defined in the arc tube between the electrodes. The fist and second in-leads are adapted to be connected to first and second power leads of a ballast circuit. A starting aid is included for the main arc tube and comprises a path generally parallel to the main arc tube along the arc gap and which is conductive during starting of the main arc tube; an electron barrier disposed between the path and the main arc tube for preventing a substantial amount of photoelectrons from collecting on an outer surface of the main arc tube; and first and second ends of the path being coupled to the first and second in-leads by first and second electrical couplings.

Abstract: A metal halide gas discharge lamp comprises an arc tube containing a vaporizable metal halide and first and second spaced electrodes. An arrangement for heating the arc tube assists in creating an arc discharge between the first and second electrodes. It comprises a heat source positioned to heat the arc tube, and an electron barrier disposed between the heat source and the arc tube for minimizing accumulation of photoelectrons on an outer surface of the arc tube so as to substantially avoid sodium migration out of the arc tube. A switch deactivates the heat source after the arc tube is heated a desired amount.

Abstract: A universal electronic ballast self-accommodates to appropriately supply power to each one of a family of different fluorescent lamps, one at a time. The ballast comprises a circuit for supplying a.c. current to a lamp in such manner that current in the lamp varies as a function of an error voltage. A summing circuit is provided together with an error amplifier for amplifying the output of the summing circuit to produce the error voltage. A circuit produces a reference voltage that is supplied to the summing circuit. A current feedback circuit feeds back to the summing circuit a first signal that varies as a function of lamp current. A voltage feedback circuit feeds back to the summing circuit at least a second signal that varies as a function of lamp voltage in such manner as to realize a ballast current-voltage characteristic that intersects respective lamp current-voltage characteristics at desired operating power for each of the family of lamps.

Abstract: A gas discharge ballast circuit comprises a resonant load circuit including a resonant inductance, a resonant capacitance, and circuitry for connection to at least one gas discharge lamp. A d.c.-to-a.c. converter circuit is coupled to the load circuit for inducing an a.c. current in the circuit. It comprises first and second converter switches serially connected in the foregoing order between a bus conductor at a d.c. voltage and a reference conductor, and connected together at a common node through which the a.c. load current flows. The first and second converter switches each comprise a control node and a reference node, the voltage between such nodes determining the conduction state of the associated switch. The respective control nodes of the first and second converter switches are interconnected. The respective reference nodes of the first and second converter switches are connected together at the common node.