Anybody else notice that the strobe rate bothers them on the newer cars with LED taillights.
At night, when the tail lights are dimmed, (brakes not on) and you look at them and blink or turn your head, the after image is very strange, you see dashes of light. I find it very annoying and distracting and I hope that this problem is recognized and corrected before every car on the road is like this.
Mark
Its the acid. Or if you are an old fart like me than it is the acid flashback.
--
Boris
That's interesting. I wonder what frequency they use to PWM the LED arrays.
The instrument cluster dimming in my Toyota runs at 400 Hz.
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ How do I set a laser printer to stun?
Oh yeah! I see individual LEDs with blurry arced paths as I move my head. It bothers me to the point of dizziness; I can't drive with such a car in front of me. And no, it isn't the acid.
- Nathan
Can't say I've noticed any issue with it. I doubt the PWM rate would be low enough to be visible, surely? BTW, I like the new LED traffic lights that are popping up all over Sydney - real funky! Anyone else find themselves distracted because you sit there counting the LEDs, or thinking "I wonder how much current they are running"? :->
Actually, the large number of point light sources in the traffic lights is a bit distracting at first glance, perhaps it is this you are actually having a problem with in the tail lights? As you turn your head it could appear to "flicker" perhaps?
Dave :)
I've seen this too. Especially the new VW's. The PWM frequency is quite low on these cars.
Meindert
Yes, the new VW's are "bad". Can't be more than 20-50Hz.
Meindert
The buses in our area are being fitted with them and I definitely find the flicker distracting.
-- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
In some areas, busses have been using LED replacement light bulbs for _years_. I designed one over five years ago, and tens of thousands have sold. In general, on these, you will not even be able to tell they were LED. The assemblies replaced the standard bulb, and included an diffuser assembly in the case, so you can't see the LED's at all. The strobe rate on these, was typically over 5Khz. What is happening now, is that new busses, and light assemblies are appearing, with the LED's built in, with different lenses. On some makes of these, the strobe rate is much lower. Many seem to be using perhaps 50/60Hz, possibly in the belief that this is fast enough to avoid flicker. Unfortunately, a light bulb on 50Hz mains, actually flickers at 100Hz, and generally has quite short 'off' periods. Even at this rate, with fast movement the flicker is visible. An LED on a
50Hz PWM, really does show up badly, and some makes may even be slower than this... It is rather 'funny', because when I did the bulb, one of the tests, from the original bus company (in the Midlands),who wanted this technology to reduce maintenance, was to ensure that you could not see such flicker, since they had received complaints that some of the then new LED 'signs' they were using, gave this effect. On these newer systems, this seems to have been forgotten. At present, the 'slowest' update, seems to be on the VAG units.Best Wishes
Hmmm Learn something every day; did not know that these arrays use PWM.
I haven't noticed tail light flicker, but then I drive very little (bicycle, and rarely in traffic). Am driving to VT for the 4th and will certainly watch out for flicker (a welcome "project", against going bonkers during the 7-hr, solo drive).
I'd think just about any PWM freq. could be problematic. Also, I am thinking about a dual strobe effect, one caused by resonances w/i my vehicle, the other caused by resonances w/i the LED vehicle. Imagine the combined effect of very rough road *plus* harmonic motion of LED fixtures. I think I'm gonna throw up.
-- Michael
And, more importantly, the ratio max_light/min_light is close to 1, whereas the same ratio for PWM'ed LEDS is infinity. The light produced at the valleys is zero.
"Mark" schrieb im Newsbeitrag news: snipped-for-privacy@u72g2000cwu.googlegroups.com...
10 years ago, the engineers of BMW used modern technology and significant effort to serve the aggressive drivers of their cars to annoy the drivers of any other manufacturers car, by installing xenon front lights with damn increased light output, ignoring that on wet streets light is shed directly into the eyes of the driver of an oncoming car, because the water on the streets acts like a perfect mirror. It took another 10 years for the engineers of BMW to come up with a solution to annoy even the drivers of cars following up. It was difficult, because just like the front lights, the back lights must also conform to law. Again the newest technology was used to screw up everyone driving behind a BMW by using far too slowly pulsing LEDs. That's BMW, worlds stupidest engineers.
And they spend an inordinate time in the shop. I wouldn't have one if you gave it to me. Rice burners reign supreme ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
And the drivers are such rude shitheads that they don't dim for approaching vehicles.
A friend countered by installing aircraft landing lights in his grill. He can only fire them up for 15 seconds at a time because the cables start smoking ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
LEDs only light up at 'one' brightness level, so to make 'em dim it has to be a brief pulse followed by a long seperation before the next pulse.
Comparing the pulsing to 120Hz, it looks to be a good bit below that.
Bugs me a little too.
Dave
I also like to annoy "beamers" by drag racing them at traffic lights... bugs the hell out of them as my 4.5 liter rice burner leaves them in the dust ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
In message , snipped-for-privacy@yahoo.com writes
Yep. It's a very noticeable flicker. I wonder if it's a standard automotive chip.
-- Clive Mitchell http://www.bigclive.com
PWM frequencies are determined by the lamp manufacturer, but most I've seen are on the order of 500 Hz - well above what is considered the flicker threshold. You shouldn't be seeing the "strobing", but since you are I would suggest filing a report with NHTSA Office of Defects Investigation (www-odi.nhtsa.dot.gov/ivoq). If enough people complain, then they can make a ruling that requires manufacturers to have a minimum PWM frequency. Make sure you include specific vehicle information (Make, Manufacturer, etc.).
As an aside - do you see this with the LED lamps that have been in use on trucks for the past 5 years? They use the same technology. Try the newer FedEx delivery trucks.
-- Douglas Cummins Calcoast - ITL
I've been behind a few I can say were no where near 500Hz.
D
Well, no, you can have the LED produce any amount of light, between none and its maximum, by varying the amount of current flowing through it. Of course this requires dropping the rest of your supply voltage across some other circuit element and so will use more power. But I think the real reason that auto manufacturers use PWM is that transistors for just on-off switching are cheap.
To join the chorus, I find them annoying also and really wish they would use a higher frequency.
--
-Harold Hill
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