Xenon headlamps, description of operation
| Xenon headlamps, description of operation |
A 70mm ellipsoid lens forms the light pattern together with the xenon lamp and reflector. The headlamp is equipped with a clear plastic protective lens that does not refract the light.
Not US/CA/JP: A halogen lamp is mounted in the lamp housing. If dipped beam is off, only the halogen lamp will come on during main beam flash.
| Xenon lamp |
The xenon lamp is a gas discharge lamp and therefore does not have a filament. The light is generated by an electrical discharge between two electrodes. The igniter is the capsule in which the discharge takes place and is filled with xenon gas and metal halogens under high pressure. The discharge generates a large amount of visible light and a certain amount of ultraviolet radiation. The xenon lamp has an outer casing that reduces the dispersion of ultraviolet radiation.
The xenon lamp is driven by the headlamp/AHL control module. The control module sends high voltage pulses to the ignition transformer for turning on the lamp. The ignition transformer, which is integrated in the xenon lamp, generates the ignition voltage (approx. 23,000 volts) that is required to turn on the lamp. Once discharge is in progress, the voltage requirement will drop to around 85V.
| Important | ||
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When changing a bulb, select a new bulb of the correct rating to prevent the components being damaged. |
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| Motor, Xenon lamp screen |
Dipped beam, xenon lamp screened
Main beam, xenon lamp unscreened
Xenon lamps always light with the same brightness. The light beam from a xenon lamp is limited by a screen which is opened for main beam use by a motor to increase the beam of light from the lamp. B+ voltage is fed to pin 2 on the headlamp and the motor opens the lamp screen.
| Control module, headlamp/AHL |
There is a control module located inside the headlamp housing that governs the supply of current/voltage to the xenon lamps. The control module also governs the stepping motors for the automatic headlamp levelling. The control module receives information on the angle of the car from the load angle sensors and regulates the angle of the headlamps based on that information.
| Headlamp levelling motor |
There is a stepping motor located in each headlamp housing. The headlamp levelling motors change the angle of the headlamps according to instructions from the headlamp/AHL control module.
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