Tuesday, January 27, 2009

Road disco? No thanks!

Video update!
Lately I have noticed that some rear lights, specially newer Volvo V70 rear lights, have a annoying blinking effect. For some reason the engineers at Volvo have chosen a blinking rate that creates a array of lights on the retina when one moves the head or the eye!

This got really tiresome when I drove to Stockholm last Sunday, at night it's specially irritating since it makes you look for cars that don't exist anywhere except like fading light on your retina!

Seems to be related to the fact that the car manufacturers uses the same lights bith as regular rear lights and braking lights. This requires that they run the LED:s och reduced 'effect' under normal conditions and when breaking they shine with full effect. To accomplish this the engineers use PWM (Pulse Width Modulation) to blink the LED:s on and off very fast so that they appear to shine less intense.

Managed to locate a thread at google groups:

Another forum where this effect is discussed, in Swedish though:

A few example images from the Swedish forum.

Regular lights:
Badly PWM:ed LED's:

I sincerely hope this kind of implementation of rear LED-lights on cars won't catch on! Other car manufacturers use this too, the new VW Passat and several Cadillac models seems to suffer from the same 'sickness'!

Managed to catch a Volvo in the act! The camera in the phone captures the 'flashing' tail light perfectly!


  1. Hm, never noticed that?

    Nice of you to be consistent with the spelling of VW/WV. ;P

  2. Ok, seems like a lot of people don't register the flashing.

    Yes, I was so upset I forgot to think like a German. :)

  3. I've noticed it. I found it very annoying.