An automotive headlamp bulb provides the two light or three filament
sources in a single bulb. One source may be used to generate a standard
headlamp beam, while the second source may be used to generate an
augmenting side beam in response to a turning signal. A similar third
filament may provide an augmenting beam to the opposite side, or farther
to the same side. The single bulb eliminates the need for a second bulb,
or a second reflector in an advanced headlamp system with turning light
augmentation.