System Overview
System overview
Bi-Xenon headlight system
1. Gas discharge lamp module (GDL) and ballast
2. High voltage unit
3. Bi-Xenon lamp
4. Actuator motor for automatic headlight levelling
5. Adjuster screws for vertical and lateral adjustment of beam
6. Position sensor, front and rear axle
7. Central electronic module (CEM)
8. Steering wheel module (SWM)
9. Light switch module (LSM)
Bi-Xenon headlight system
Bi-Xenon, a headlight system with projector module, 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.
There are two gas discharge lamp modules (GDL) - one for each headlight. The one located on the driver's side of the vehicle serves as "master" and communicates with the central electronic module (CEM) via LIN communication.
The other gas discharge lamp module (GDL) serves as "slave" and communicates with the "master" control module via LIN communication.
The gas discharge lamp module (GDL) and ballast are integrated into a single unit and are mounted behind the headlight in the wheel arch liner.
Ballast
Warning! The ballast, which is located in the wheel arch liner, and the wiring for the Bi-Xenon lamps are high voltage.
An electronic ballast is connected to each headlight. The ballast serves as a voltage regulator and generates alternating current (AC).
The ballast and gas discharge lamp (GDL) module are integrated into a single unit.
The main tasks of the ballast are:
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.
Bi-Xenon 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: D2S (special for projector modules).
- Power consumption: 35 W.
Caution! The bulb contains mercury (less than 0.5 mg), thus classifying it as hazardous waste. Hazardous waste must be handled in accordance with national legislation. See also Volvo Car Corporation's "Waste Management Guidelines for Dealers."
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 more restful the light is to the eyes. A standard H4 bulb has a color temperature of about 3200 °K. The Volvo gas discharge bulb has a color temperature of 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.