Patent ID: 6583536
Filing Date: 2003-06-24
Classification: H01K

Abstract:
A lamp, comprising:an envelope having an interior; a primary filament having a first end and an opposing second end; a secondary filament having a first end and an opposing second end; a primary electrode extending through said envelope; a common electrode extending through said envelope; a secondary electrode anchored in said envelope, said primary, common and secondary electrodes being spaced apart, said first end of said primary filament being connected to said primary electrode, said second end of said primary filament being connected to said common electrode, said first end of said secondary filament being connected to said common electrode, and said second end of said secondary filament being connected to said secondary electrode; a tertiary electrode; a tertiary filament; a tertiary electrode shunt, said tertiary electrode shunt in series electrical connection with said tertiary filament and in parallel electrical connection with said primary filament and said secondary filament; and switch means in electrical connection with said primary electrode and said secondary filament for directing current through said secondary filament when said primary filament fails and causing said secondary filament to provide illumination outside of said envelope.