Design

Design

Bi-Xenon headlight system









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 headlight levelling.

Xenon vs. Halogen

Xenon:
- higher color temperature, which produces a whiter light
- better reflection of road signs and road markings
- has lower power consumption (about 2/3).

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.

Lamp
The light source consists of a discharge tube surrounded by a glass that filters out harmful UV radiation.
- The discharge tube is filled with a blend of chemical compounds, including the inert gas Xenon.
- An electric arch is created through an electrical discharge between two tungsten electrodes.
- Because the lamp does not have a filament, it is less sensitive to bumps and vibrations.
- Bulb designation: D2R (special for reflector system).
- Power consumption: 35 W.

Caution! The bulb contains mercury (less than 0.5 mg) and when discarded must be treated as hazardous waste. Hazardous waste must be handled according to the relevant statutory regulations, see also Volvo Car Corporation's "Waste Management Guidelines for Dealers".

Ballast
An electronic ballast is connected to each headlight. The ballast serves as a voltage regulator and generates alternating current (AC).

Primary tasks:
1. Light the bulb.
2. Regulate light during operation.
A initial voltage of about 24,000 V for a very brief period (less than 1 ms) is required to light the bulb.
The ballast transforms the vehicle's 12 V (DC) to 1000 V (AC).
The high voltage contact amplifies the voltage an addition 25 times.
Once the bulb has been lit, voltage is regulated down to about 100 V, which is required to keep the bulb lit.
Power consumption: 10 W.