"Major Scott" wrote
On Tue, 23 Apr 2013 11:36:27 +0100, DavidR wrote:

The effect relies on the persistance of the eyes to make it appear that
the average brightness is higher.

Easy enough to double the frequency of the flicker, then you wouldn't
notice it. Remember 50Hz CRT monitors?

Smoothing at source would be less energy efficient.

I don't believe you. Switched mode power supplies are very cheap
nowadays, especially compared with the cost of a car, especially a £100K
car which has the same problem.

What is generated
------ ------
| | | |
| |______| |_____

What the eye perceives
-------- --------
| \ | \
| \___| \____

By averaging the power in the top waveform, the peak intensity is reduced
and would not use eye's ability to fill in the gaps. Therefore a
smooth waveform requires more power at source.

Picking a Cree led at random, the data sheet shows that the increase in
luminous output falls relative to the increase in current (ie, doubling the
current produces less than a doubling of output), so at first sight it would
seem that pulsing is counterproductive. Which means that there are other
factors that make it advantageous.

and brake light dimming when conditions suggest a slow moving queue.

I don't agree with different brightnesses of brakes. We already have two
brightnesses of red - tail and brake. Adding more would just lead to
confusion, you would wonder if it was a tail or a brake.

If you can't maintain a gap in a slow moving queue without the help of brake
lights, are you sure you're competent?