Ballast circuit for direct current arc lamp
AssigneeGTE Laboratories Incorporated
InventorCarl F. Buhrer
Life of this patent
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Abstract
A high efficiency controlled direct current source for operating high pressure mercury or metal halide lamps for use as substitutes for ordinary incandescent lamps. The circuit includes a voltage sensitive circuit for pulsed starting of the arc discharge lamp as well as for the activation of an auxiliary incandescent filament during the warm-up or hot restart of the arc.
Claims9
A combination discharge, incandescent lamp assembly including a miniature arc discharge lamp, an incandescable filament, and a thermal switch having break and make contacts mounted within a sealed outer envelope, and a control circuit in a common assembly arranged to operate from an alternating current source, said control circuit comprising:
- rectification means, having a pair of output terminals, for converting an input alternating current to a direct current across said output terminals;
- a first series circuit connected across said direct current output terminals, said first series circuit including said incandescable filament, said break contacts of said thermal switch, a first inductor, and said discharge lamp, said break contacts being closed until said discharge lamp reaches a predetermined operating temperature;
- a controlled rectifier connected in series with said make contacts of said thermal switch across said output terminals, said make contacts being closed when said discharge lamp reaches said predetermined operating temperature;
- a second series circuit connected in parallel with said controlled rectifier, said second series circuit including a capacitor and a second inductor magnetically coupled to said first inductor said circuit receiving charge from said direct current output terminals;
- a gate control circuit connected in parallel with said discharge lamp and responsive to lamp voltage and to a gate of said controlled rectifier for causing said controlled rectifier to periodically conduct upon energization of the control circuit to cause pulses to be coupled from said second inductor across said first inductor to boost the voltage across said discharge lamp for igniting the same and for causing said controlled rectifier to cease conducting upon initiation of an arc mode in said discharge lamp, and for causing said controlled rectifier to conduct to cause current flow through said incandescable filament when discharge in said discharge lamp is extinguished and said make contacts are closed.
Dependencies are inferred from the claim text.