Direct current power source for an electric discharge lamp

A ballast circuit for connecting a high intensity discharge lamp to a source of direct current energy comprising, in combination,

• a VMOS insulated-gate field effect transistor having a gate-electrode and a source drain channel,
• a fixed ballast resistor connected in parallel with said channel,
• a current sensing resistor for connecting the parallel combination of said channel and said ballast resistor in series with said lamp,
• a voltage sensing resistance connected to said lamp, and
• a control transistor having an input circuit connected to said sensing resistors and having an output circuit connected to the gate of said field effect transistor.

A self-ballasted HID lamp comprising, in combination,

• an electric discharge vapor arc tube and a tungsten filament mounted within a glass bulb,
• a VMOS insulated-gate field-effect transistor transistor having a control electrode and a transconductive path,
• circuit means for connecting said transconductive path in series with said arc tube and in parallel with said filament, and
• means connected to said control electrode for increasing the conductivity of said transconductive path in response to increases in the vapor pressure within said arc tube.

A self-ballasted lamp comprising, in combination,

• a glass bulb,
• a lamp base having external conductive contact means adapted to establish electrical connections to an alternating current power supply socket,
• a neck section attaching said bulb to said base,
• an electric discharge vapor arc tube mounted within said bulb,
• a resistive filament adapted to be heated to incandescence mounted within said bulb, and
• an electronic control circuit mounted within said neck section, said control circuit comprising, in combination,
• a rectifier having an input circuit connected to said conductive contact means and an output circuit forming a source of a direct current potential,
• a transistor having a control electrode and a transconductive path,
• circuit means for connecting said transconductive path in series with said arc tube across said source,
• circuit means connecting said filament in parallel with said transconductive path, and
• means connected to said control electrode and responsive to the magnitude of electrical energy delivered to said arc tube for controlling the conductivity of said transconductive path.

An improved power supply for operating an electric vapor discharge lamp comprising, in combination,

• a source of a direct-current potential,
• a vertical Metal Oxide Semiconductor Field Effect Transistor (MOSFET) having a source-drain channel and a gate electrode,
• means connecting said source-drain channel in series with said lamp across said source,
• and means for supplying a control potential to said gate electrode to increase the conductivity of said source-drain channel in response to increases in the vapor pressure in said lamp as it is heated following ignition.

A solid-state ballast circuit for supplying power to a high intensity discharge lamp from a source of an electrical potential which comprises, in combination,

• a Vertical Metal Oxide Semiconductor Field Effect Transistor (VMOS FET) having a source-drain channel and a gate electrode,
• a current sensing resistor serially connected with said lamp across said source,
• a fixed resistor connected in parallel with said channel,
• a bipolar transistor having a collector-emitter path and a base-emitter path,
• means connecting said base-emitter path in parallel with said current sensing resistor, and
• means connecting said collector-emitter path to said gate electrode to control the conductivity of said channel.