Bi-Xenon Headlight System

Fig 1: Identifying Bi-Xenon Headlight System

Courtesy of VOLVO CARS CORPORATION

1. Left headlamp control unit (LHCU)/Right headlamp control unit (RHCU) (vehicles with active headlamps only)
2. Motor, headlight levelling
3. Lamp contact, high voltage
4. Bi-Xenon lamp
5. Internal headlight edge
6. Motor, high and low beam

Bi-Xenon, a headlight system with moveable reflector, is based on gas discharge technology. The system combines high and low beam into the same lamp.

Due to legal requirements (regarding low beam) for this type of lamp, the vehicle must be equipped with automatic headlamp levelling.

Xenon vs. Halogen 

Xenon:

• higher color temperature, which produces a whiter light
• better reflection of road signs and road markings
• lower power consumption (approx. 65% lower).

Good to know: 

• Daylight has a color temperature of about 5000°K. The closer to natural light, the less strain on the eyes. Standard H4 bulb: 3200°K. Volvo's gas discharge bulb: about 4200°K.
• With the Bi-Xenon system, high and low beam generates the same light color. The human eye thus has an easier time adjusting to switches between high and low beam.