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Car LED tail lights strobe rate too slow

M

Mark

Jan 1, 1970
0
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
 
B

Boris Mohar

Jan 1, 1970
0
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.
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
Mark said:
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.

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.
 
N

Nathan Hunsperger

Jan 1, 1970
0
Anybody else notice that the strobe rate bothers them on the newer cars
with LED taillights.

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
 
D

David L. Jones

Jan 1, 1970
0
Mark said:
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

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 :)
 
M

Meindert Sprang

Jan 1, 1970
0
Mark said:
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.

I've seen this too. Especially the new VW's. The PWM frequency is quite low
on these cars.

Meindert
 
M

Meindert Sprang

Jan 1, 1970
0
David L. Jones said:
Can't say I've noticed any issue with it. I doubt the PWM rate would be
low enough to be visible, surely?

Yes, the new VW's are "bad". Can't be more than 20-50Hz.

Meindert
 
A

Adrian Tuddenham

Jan 1, 1970
0
Mark said:
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.

The buses in our area are being fitted with them and I definitely find
the flicker distracting.
 
R

Roger Hamlett

Jan 1, 1970
0
Adrian Tuddenham said:
The buses in our area are being fitted with them and I definitely find
the flicker distracting.
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
 
M

Michael

Jan 1, 1970
0
Paul Hovnanian P.E. said:
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.


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.
 
M

Mochuelo

Jan 1, 1970
0
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.

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.
 
M

MaWin

Jan 1, 1970
0
Mark said:
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.

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.
 
J

Jim Thompson

Jan 1, 1970
0
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
 
J

Jim Thompson

Jan 1, 1970
0
[snip]
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.
[snip]

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
 
Paul said:
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.

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
 
J

Jim Thompson

Jan 1, 1970
0
[snip]
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.

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
 
C

Clive Mitchell

Jan 1, 1970
0
In message said:
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.

Yep. It's a very noticeable flicker. I wonder if it's a standard
automotive chip.
 
D

Douglas G. Cummins

Jan 1, 1970
0
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

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 said:
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.

I've been behind a few I can say were no where near 500Hz.

D
 
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.

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.
 
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