Optically-coated dual-filament bulb for single compartment headlamp

摘要

A dual-filament reflective infrared bulb has high and low beam filaments in spaced adjacency along a longitudinal bulb axis. A longitudinal envelope structure encloses each filament in a separate substantially ellipsoidal chamber. The outer surface of the envelope structure is coated with dichroic layers and provides focused reflectance of infrared radiation back onto the filaments. The common ground lead of the assembly passes through one of the chambers substantially off of the longitudinal axis and thereby off of the focal axis of the infrared radiation. A lead emanates out of one longitudinal end of the envelope structure and is formed to return in spaced adjacency toward the opposite longitudinal end. A bulb shield is fastened to the return portion of the lead and intermediate one of the chambers and the leads.