Xenon Headlamps, Description of Operation

Xenon Headlamps, Description Of Operation

General







The headlamp contains a xenon lamp with ignition transformer, control module, beam length adjustment motor, halogen bulb and parking light bulb.

A 70 mm 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.

There is a halogen bulb mounted in the lamp housing. Only the halogen bulb lights up when the main beam flashers are used while the dipped beam is turned off.

The halogen bulb does not come on simultaneously with the xenon lamp for main beam on the US/CA/JP markets.

On other markets, the halogen bulb comes on together with the xenon lamp for main beam.

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 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. 23000 volts) that is

required to turn on the lamp. Once the discharge is in progress, the voltage requirement will drop to around 85 V.


IMPORTANT
When changing a bulb, select a new bulb of the correct rating to prevent the components being damaged.


Solenoid, 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 solenoid to increase the beam of light from the lamp. B+ voltage is fed to pin 2 on the headlamp and the solenoid opens the lamp screen.


AHL control module







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 beam length adjustment. 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 beam adjustment motor







There is a stepping motor located in each headlamp housing. The headlamp beam adjustment motors change the angle of the headlamps according to instructions from the AHL control module.