Lighting unit
 A lighting unit is described utilizing an energy efficient metal vapor arc lamp as the main source of light supplemented by a standby filamentary light source producing light when the arc lamp is being started. The lighting unit is designed as a more efficient replacement for the incandescent lamp. The lighting unit includes means for conversion of 60 hertz ac to dc, and a dc energized operating network, including a ferrite transformer and an intermittently operated switching transistor serially connected with a load consisting of the filament or the arc lamp, or both, to which regulated output power is provided. The operating network produces an output with minimum dissipation adapted to each operating state of the arc lamp, including the provision of a high ignition potential, adequate power for the lamp during the glow to arc transition, warm-up and ballasting. In addition, while the arc lamp is being started, the operating network provides power for lighting the standby filament. 
General Electric Company
H H
H01J H01J
inventional inventional
William Thomas A.
Peil Brown