Lumileds, the name behind the Philips brand of automotive lighting and accessories, has issued some useful information on the importance of quality when it comes to choice of headlight bulbs.

The company says many buyers tend to think of bulbs as a commodity when they are in fact high precision products. While a normal household bulb distributes its light over a radius of just a few metres, a headlight bulb combined with the reflector has to transfer the light accurately onto the road at a distance much greater than 50 metres.

Halogen headlight bulbs are manufactured and approved in accordance with the legal requirements (ECE R37). The specifications include the permitted luminous flux in lumen, the electrical power consumption and all the dimensions, from the glass bulb itself, to the base. This specification aims to ensure, for example, that every approved H7 bulb fits in every headlight intended to be used with an H7 bulb and that the combination provides the correct light beam.

Bulbs produced by manufacturing brands such as Philips, who also supply original equipment, meet the stringent requirements of ECE R37, but their in-house specifications are often even stricter. This requires high-precision manufacturing processes and extremely stringent quality assurance inspections.

Comparison tests carried out by motoring journals repeatedly demonstrate that many bulbs manufactured using cheap production techniques fail to meet these high standards, with errors in the geometry being the main problem. The result is an imprecise light beam, a range that is far too short, or glare. If the filament is too far from the reflector, the light beam is too short; if it is too close, this creates glare.

Even some bulbs that carry the E-mark perform poorly in comparison test, usually due to production standards that do not match up to the initial approved product.

Richard Armstrong, Business Development Manager Automotive at Lumileds said, “Despite the introduction, in recent years of new lighting technology such as Xenon and LED, most cars on the road currently still use halogen lights. Simply replacing the bulb, for example with a H4 or H7 X-tremeVision, can generate a light beam that is up to 130% brighter and 45 metres longer.” He adds, “We are frequently told not to touch halogen bulbs with bare hands, but the biggest problem here is not the oils that can burn into the glass and cause damage, as this would require an enormous level of contamination. What is much worse is even the smallest amount of contaminants that evaporate in the headlights and deposit themselves on the sensitive mirror surfaces. This can cause an unsightly coating to build up relatively quickly, which will affect the lighting quality at some point. So the best thing is to always wear suitable gloves.”

Richard points out that one out of every two new cars sold in Europe will have a Philips bulb fitted. Manufactured from high quality products and tested to the highest specifications.