Xenon Headlamp
- The xenon system generates up to 28000 Volts and contact with this voltage could lead to fatality. Make sure that the headlamps are switched off before working on the system.
- The following safety precautions must be followed when working on a xenon headlamp system:
- DO NOT attempt any procedures on the xenon headlamps when the lights are switched on.
- Handling of the xenon bulb must be performed using suitable protective equipment, for example gloves and goggles. The glass part of the bulb must not be touched.
- Xenon bulbs must be disposed of as hazardous waste.
- Only operate the lamp in a mounted condition in the reflector.
| ITEM | DESCRIPTION |
|---|---|
| 1 | Headlamp mounting bracket |
| 2 | Side marker lamp LED (NAS only) |
| 3 | Headlamp mounting bracket |
| 4 | Projector module - low/high beam headlamp |
| 5 | Daytime Running Lamps (DRL) |
| 6 | Turn signal indicator |
| 7 | Static bending lamp (Not NAS) |
| 8 | Cooling bodies |
| 9 | Vertical adjuster |
| 10 | Turn signal bulb access cover |
| 11 | Xenon Bulb Control Module (XBCM) |
| 12 | Electrical connector |
| 13 | LED Driver Module (LEDDM) |
| 14 | Horizontal adjuster |
| 15 | Xenon igniter access cover |
The xenon headlamp operates as both a low and high beam unit. The unit comprises a reflector, an adaptor ring, the lens, a shutter controller and the xenon bulb, which together is an assembly known as the projector module. The projector module is installed in a carrier frame that allows the module to tilt for vertical movement of the headlamp beam. Vertical movement is controlled by an actuator, connected between the carrier frame and the projector module, operated by the BCM/GWM assembly for automatic headlamp leveling.
The reflector is curved and provides the mounting for the xenon bulb. The bulb locates in a keyway to ensure correct alignment in the reflector and is secured by a plastic mounting ring. The shutter controller is a solenoid which operates the shutter mechanism via a lever. The shutter is used to change the beam projection between low and high beam.
The xenon headlamps are controlled by the BCM/GWM assembly using a xenon bulb control module and a xenon bulb igniter for each headlamp. These provide the regulated power supply required to illuminate the xenon bulbs through their start-up phases of operation.
The xenon bulbs illuminate when an arc of electrical current is established between two electrodes within the bulb. The xenon gas sealed in the bulb reacts to the electrical excitation and the heat generated by the current flow produces the characteristic blue/white light.
To operate at full efficiency, the xenon bulb goes through three stages of operation before the output for continuous operation is achieved. The three phases are; start-up phase, warm-up phase and continuous phase.
In the start-up phase, the bulb requires an initial high voltage starting pulse of up to 28000 Volts in order to establish the arc. This high voltage starting pulse is produced by the igniter and, once the arc is established, the warm-up phase begins. During the warm-up phase, the xenon bulb control module regulates the supply to the bulb to 2.6 A which gives a lamp output of 75 W. While in this phase, the xenon gas begins to illuminate brightly and the environment within the bulb stabilizes, ensuring a continual current flow between the electrodes. Once the warm-up phase is complete, the xenon bulb control module changes to continuous phase. The supply voltage to the bulb is reduced and the operating power required for continual operation is reduced to 35 W. The process from start-up to continuous phase is completed in a very short time.
The Xenon Bulb Control Module (XBCM) (one per headlamp) receive an operating voltage from the BCM/GWM assembly when the headlamps are switched on. The XBCM regulate the power supply required through the phases of start-up.
The xenon bulb igniters (one per headlamp) generate the initial high voltage required to establish the arc. The igniters have integral coils which generate the high voltage pulses required for start-up. Once the xenon bulbs are operating, the igniters provide a closed circuit for the regulated power supply from the XBCM.