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Signal Lamps: LEDs Give…And Take? PDF Print E-mail
Monday, 24 May 2010

By Daniel Stern, Driving Vision News 

Everyone knows the benefits of LEDs for brake and signal lighting: they last forever, they light up quickly, they take much less power than a filament bulb to produce equivalent light, they offer new packaging and styling possibilities, and so on. But there are pesky new difficulties arising, as often happens when new technologies collide with older testing and regulatory practices.

LED brake and tail lamps have quickly and almost completely come to predominance on trucks and buses in North America. In that market, almost all large commercial vehicles use one of just a few standard rear lamp formats, by far the most popular of which is the 100mm (4-inch) diameter round. Lamps of this format are the smallest circular lamps that meet the U.S. Effective Projected Luminous Lamp Area (EPLLA) requirement. On vehicles wider than 203 cm, brake and tail lamps must have an EPLLA of 75cm2 . It is not permitted to accumulate the required EPLLA with multiple lamps; no matter how many brake and tail lamps are fitted, each and every individual lamp must meet the EPLLA requirement by itself. An ordinary bulb-type 100mm lamp (accounting for occlusion by the mounting bezel) is just barely above 75cm2; its whole lens area is lit. But most LED 100mm round lamps use multiple emitters. When powered, these lamps produce a visual signal of between 5 and 40 dots with dark space amongst the emitters.

The dark space isn't lit and so can't be counted when calculating the lamp's EPLLA. But the regulation does not provide a definitive method for measuring a lamp's EPLLA. The assumption, based on lamps equipped with conventional filament bulbs, is that the only unlit areas might be round the edges of the lamp. Compliance testing labs and industry working groups have devised and proposed various methods of measuring EPLLA, and some of these appear to give consistent, realistic, repeatable results—but none of them is an official method. Meanwhile, American regulators have raised concerns about lamps on the road that don't meet EPLLA requirements, but there's been little enforcement action, probably due in part to the lack of an official test protocol. For now, there are noncompliant lamps on the road and nobody's quite sure what to do about it.

Nor is it entirely clear what the relative safety effect is of this particular kind of noncompliance.

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I apologise to all who felt excluded of Paris DVN workshop PDF Print E-mail
Monday, 17 May 2010
In my editorial last week, I presented the first thoughts on the Paris DVN workshop.
Several Gold members of Driving Vision News have asked me why they were not invited to this interesting workshop. The main reason was that it is not a congress but a meeting with restricted participation in order to have a deep discussion among the attendees, all experts on headlighting.
So, I decided to only invite the European carmakers and tier-1 lighting suppliers and the worldwide light source suppliers which are totally involved in the subject of this workshop.

I apologise to all who felt excluded, and I have a proposal: I will organise another workshop with tier-1 and tier-2 lighting suppliers as well as institutes, universities and labs.
After the Paris DVN workshop, much information has to be transmitted to these companies and I am sure they will be able to help a lot, bringing tools to the enormous new technologies and lighting functions arriving in the market.

After the summer holidays, I will join all of you to prepare this new workshop which will be held at the east of France or in Germany. From now, if you have ideas, please do not hesitate to send me them in order to achieve a workshop at the same quality as the Paris workshop. I will publish a special report of Paris DVN workshop with the lectures and the results of the round tables; you will soon receive information as though you had been at the meeting.

Together, we're bolstering the communication and interaction within our community. Let's keep at it—together!

Sincerely yours 

DVN, General editor

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