Can't find the thread as my server deletes too soon but last month somebody
was asking when LED lighting will out-do halogen and CFL.

A new press release from http://www.cree.com/News/news214.asp shows this
isn't too far off, say 12-18 months, 24 at worst.

"Anna Kettle" wrote in message
...
On Thu, 17 Feb 2005 22:07:17 -0000, "Mike" wrote:

Can't find the thread as my server deletes too soon but last month
somebody
was asking when LED lighting will out-do halogen and CFL.

A new press release from http://www.cree.com/News/news214.asp shows this
isn't too far off, say 12-18 months, 24 at worst.

Thankyou, that was me. I had a look at the link and they do seem to be
hedging their bets still


You have too. Say anything too optimistic and you get sued by investors if
you don't deliver. But I've seen the product and it is impressive.

Mike wrote:

"Anna Kettle" wrote in message
...
On Thu, 17 Feb 2005 22:07:17 -0000, "Mike" wrote:

Can't find the thread as my server deletes too soon but last month
somebody
was asking when LED lighting will out-do halogen and CFL.

A new press release from http://www.cree.com/News/news214.asp shows this
isn't too far off, say 12-18 months, 24 at worst.

Thankyou, that was me. I had a look at the link and they do seem to be
hedging their bets still


You have too. Say anything too optimistic and you get sued by investors if
you don't deliver. But I've seen the product and it is impressive.

Got a way to go before it becomes economical though.
38W tube (installed) costs maybe 20 quid.
LED of the same power maybe 180.

And those LEDs that cree are advertising produce very poor white light
for general use.

In article ,
Ian Stirling wrote:
You have too. Say anything too optimistic and you get sued by
investors if you don't deliver. But I've seen the product and it is
impressive.

Got a way to go before it becomes economical though.
38W tube (installed) costs maybe 20 quid.
LED of the same power maybe 180.

And those LEDs that cree are advertising produce very poor white light
for general use.

Yes. To me, continuous spectrum light is needed for a pleasant environment.
The cost of running such lighting isn't really significant in most
households.
Security, etc, lighting is rather different.

--
*Reality is a crutch for people who can't handle drugs.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Ian Stirling wrote:
You have too. Say anything too optimistic and you get sued by
investors if you don't deliver. But I've seen the product and it is
impressive.

Got a way to go before it becomes economical though.
38W tube (installed) costs maybe 20 quid.
LED of the same power maybe 180.

Aim is not quite that much but I think in the original thread there was a
problem with using halogens which LEDS overcome


And those LEDs that cree are advertising produce very poor white light
for general use.

12v halogens aren't true white either. In the end one needs to look at all
the products and choose the one you like best. But this product is
attracting serious attention in stage lighting as well as automotive
headlights.

In article ,
Mike wrote:
12v halogens aren't true white either.

But they are continuous spectrum.

In the end one needs to look at all
the products and choose the one you like best. But this product is
attracting serious attention in stage lighting as well as automotive
headlights.

Specialist applications aren't quite the same as domestic.

--
*It sounds like English, but I can't understand a word you're saying.

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Mike wrote:
12v halogens aren't true white either.

But they are continuous spectrum.

In the end one needs to look at all
the products and choose the one you like best. But this product is
attracting serious attention in stage lighting as well as automotive
headlights.

Specialist applications aren't quite the same as domestic.

Well, not being impressed with the 30 quid 5 LED Cateye cycle light I
ordered, I've just finished my prototype fluorescent front light to replace
the 12 volt 21 watt incandescent I was using .

Made by carefully removing the ballast from a 9 watt mini-spiral, driving it
with the invertor from a camping light and fitting it in a
conveniently-sized "tupperware".

It remains to be seen whether it stands up to my twice-daily assault on
Bristol's traffic in all weathers ...

http://uk.geocities.com/gentlegreengiant/cyclelight.JPG

I may well buy myself a shed-load of red LEDs for the back though ...

Jeremy

A uk.d-i-y primer on LED lighting.



First there is no realistic chance of LED lighting becoming widespread
practical domestic lighting in 2 years. LEDs have too many and too
large issues.

They are excessive cost, low light quality, rapid deterioration of
output, and the fact that there are much better technologies around.

LEd lighting is a hype business. Other technologies show far more
promise, and have done all along.


Full spectrum lightig is another widely misunderstood subject. 3
discrete spectral lines can produce CRI of over 90%. People can not
normally tell the difference between 91% and 100%. Triphosphor lights
are widely sold as full spectrum, although theyre nothing of the sort.

Due to the nature of the human eye, full continuous spectrum lighting
is not needed.

Many non full spectrum tubes do look inferior, hence many have formed
the mistaken belief that full spectrum is needed for good eye appeal.
However in a lot of cases the lamps they were comparing were not as
described anyway, with discrete spectrum triphosphor lamps being
routinely sold as full spectrum.


12v halogens are the truest white of all domestic light sources, with
CRI of apx 100%, colour temp of 3000K and a full continuous spectrum.
As far as whiteness goes, theyre as good as it gets.


But this product is
attracting serious attention in stage lighting as well as automotive
headlights.

Serious hype, not serious attention. LEd lighting will not be taken up
any day soon by lighting professionals. This press release is aimed
directly at those without lighting expertise.


I've cross posted this to sci.engr.lighting so any errors or debatables
can be picked up by the real experts.


NT

wrote:


Serious hype, not serious attention. LEd lighting will not be taken up
any day soon by lighting professionals. This press release is aimed
directly at those without lighting expertise.


I've cross posted this to sci.engr.lighting so any errors or debatables
can be picked up by the real experts.


NT


but not to a stage lighting forum. There is REAL interest, and many
products already in the market place. Chromabank is just the first to
spring to mind http://www.pulsarlight.com/ChromaBank.htm

They're not really being touted for their ability to produce white
light, but because they can be driven as colour mixing units. Given
power and three control channels you mix whatever you want. (except
perhaps a good white :-) )

In article ,
Andrew Chesters wrote:
but not to a stage lighting forum. There is REAL interest, and many
products already in the market place. Chromabank is just the first to
spring to mind http://www.pulsarlight.com/ChromaBank.htm

They're not really being touted for their ability to produce white
light, but because they can be driven as colour mixing units. Given
power and three control channels you mix whatever you want. (except
perhaps a good white :-) )

Yes - I've seem them used for cyclorama lighting where the ability to give
near any perceived colour (on TV) is very useful - as is their small size
and lower heat, a safety factor when used near cloth etc.

However, that's a specialist application where costs are pretty
irrelevant, and a long way from general purpose - or even mood - domestic
lighting.

--
*Nostalgia isn't what is used to be.

Dave Plowman London SW
To e-mail, change noise into sound.

Andrew Chesters wrote:
wrote:

Serious hype, not serious attention. LEd lighting will not be taken up
any day soon by lighting professionals. This press release is aimed
directly at those without lighting expertise.

snip

but not to a stage lighting forum. There is REAL interest, and many
products already in the market place. Chromabank is just the first to
spring to mind http://www.pulsarlight.com/ChromaBank.htm

They're not really being touted for their ability to produce white
light, but because they can be driven as colour mixing units.

Hmm. Yes, they are being used quite a lot in big-budget stage lighting
applications (because most theatres still can't afford them). IMHO this
is mostly because they are the newsest and trendyest thing, so every
show wants to be seen to be using them. It's rare to find them in use
out of sight!

The colour-mixing LED battens that are seen on TOTP, etc., are really
only an update of 1930s (?) technique. In those days we had battens of
150W tungsten lamps on three or four circuits, in which you put
different colours. Frequently those colours were RGBW, to allow for
colour mixing.

Then the same was done with linear halogen floods. This was much
brighter and, with an asymmetric reflector, more useful for lighting cloths.

Then the same was done with MR-16s ("zip strips"). This was a dramatic
improvement because the individual cells (each lamp) were so much
smaller, and so more closely spaced. This made it much easier to get a
smooth wash at a short throw distance.

The same thing is now being done with LEDs. They are an even smaller
source, meaning that
(a) You can get a smooth wash in any colour from really close. I've seen
them used in conference lighting by laying a strip of them along the
bottom of the backdrop, touching the flats.
(b) The sources are small enough that from a distance, the eye doesn't
see the individual colours. Same effect as an LED video screen, and
useful if you're shining them toward the audience, as they simply see a
colour-changing light rather than lots of little RG&B sources being mixed.

Both of these are valid reasons for using LEDs. But IMHO, there are only
a very few applications where this justifies their cost.

The entertainment application where I think LEDs will be very useful is
one that receives less attention, and that is as a replacement for fibre
optics in starcloths and other effects. The point of light is nearly as
small, and there is no external box with a noisy fan and a hot lamp to
worry about. An LED starcloth was on show last September at PLASA, and I
think we'll be seeing a lot more of them.

--
"This book is dedicated to my brilliant and beautiful wife
without whom I would be nothing. She always comforts and
consoles, never complains or interferes, asks nothing, and
endures all. She also writes my dedications." - Albert Malvino
---------------------------------------------------------------
Simon Waldman, UK email:
---------------------------------------------------------------

wrote in message
ups.com...
But this product is
attracting serious attention in stage lighting as well as automotive
headlights.

Serious hype, not serious attention. LEd lighting will not be taken up
any day soon by lighting professionals. This press release is aimed
directly at those without lighting expertise.

I think the contracts already placed indicate otherwise. This product is
being taken VERY seriously in stage lighting, but how long this takes to
transfer to the home remains to be seen.

Can mix any colour you like as long as you can get round some patent
issues...

There is at least one 7 colour LED based colour mixing unit and a
couple that have added Amber to the RGB mix.

Adam

They are excessive cost,

Competition is good, Lumileds are no longer the only high power LED
maker.

low light quality

White phopshor LEDs are getting better, look at the warm white LEDs now
around and see above comment about additive mixing of colour LEDs.

rapid deterioration of
output,

Not as bad as it was, Lumileds claim 50K Hour lumen maintenace for
their 1W Luxeon LED.

and the fact that there are much better technologies around.

Which are?

LEd lighting is a hype business. Other technologies show far more
promise, and have done all along.

Wouldn`t disagree that their is some damaging , to long term acceptance
of LEDs, hype around, but please what are these other techologies
showing more promise, EL, mebbe not, Metal Halide mebbe gots some more
mileage in it, fluorescent still a good performer room for improvement
, probably,.

Cree X Lamp is currently brightest on block, Lumileds followed with a
press release saying their new LEDs would be out in the summer, didn`t
say which summer. Nichia have their high power Jupiter out ,
Korean/Chinese UFO high power LED has been out a while now, heck even
humble 5mm LED has got brighter

http://ledmuseum.home.att.net/ledwht.htm

Don`t think LEDs are a panacea but in some applications they are the
best choice light source.

Adam

In article ,
Steve Firth wrote:
They are excessive cost, low light quality, rapid deterioration of
output, and the fact that there are much better technologies around.

Funny, in the work I do LEDs are replacing incandescent at one heck of a
pace because the problems you mention are non-existent (indeed colour
stability with LEDs is better) and service life is much greater.

I'm curious - as a sound engineer - in that I've not seen them replacing
keys or fills yet, but merely as dressing lights. On location, spots still
tend to be HMIs (HID) and soft Kinoflows etc which are basically
fluorescents. But perhaps I only work on low budget stuff. ;-)
In studios, where size, heat and power consumption ain't an issue, halogen
still rules. Apart from dressing lights.

--
*Why isn't there a special name for the back of your knee?

Dave Plowman London SW
To e-mail, change noise into sound.

"Steve Firth" wrote in message
.. .
wrote:


They are excessive cost, low light quality, rapid deterioration of
output, and the fact that there are much better technologies around.

Funny, in the work I do LEDs are replacing incandescent at one heck of a
pace because the problems you mention are non-existent (indeed colour
stability with LEDs is better) and service life is much greater.


Agreed - I think the worst case LEDs are 50k hours - about 5 to 50 times the
life of an incandescent or CFL.

In message . com,
writes
Serious hype, not serious attention. LEd lighting will not be taken up
any day soon by lighting professionals. This press release is aimed
directly at those without lighting expertise.

LED lighting used EXTENSIVELY in the television industry for effects and
prop detail illumination.

--
Clive Mitchell
http://www.bigclive.com

google dinnae quote properley, and darn uni-berlin going pay to play..

Agreed - I think the worst case LEDs are 50k hours - about 5 to
50 times the
life of an incandescent or CFL

Afraid worst case is a sight worse than that

http://www.lrc.rpi.edu/programs/soli...pdf/guSPIE.pdf

Look at the curves for white LEDS, down 10% within first 1K hours and
falling.

Not all LEDs are same, and white is the worst case, but its the hype
that ain`t helping.Bit of a reality check at LRC:

http://www.lrc.rpi.edu/programs/solidstate/

Adam

In article , Mike wrote:

"Steve Firth" wrote in message
. ..
wrote:


They are excessive cost, low light quality, rapid deterioration of
output, and the fact that there are much better technologies around.

Funny, in the work I do LEDs are replacing incandescent at one heck of a
pace because the problems you mention are non-existent (indeed colour
stability with LEDs is better) and service life is much greater.


Agreed - I think the worst case LEDs are 50k hours - about 5 to 50 times the
life of an incandescent or CFL.

Actually, for white LEDs at full power 50K hours is the high end of
claims not easily "shot down". White LEDs have a problem with phosphor
deterioration, which is not a problem with colored LEDs.

As for actual life expectancy of white LEDs - I have heard enough
figures anywhere from 6K to 50K hours for good ones! Less if you push
them or do not keep them cool!

- Don Klipstein )

In article , Steve Firth wrote:
Dave Plowman (News) wrote:

I'm curious - as a sound engineer - in that I've not seen them replacing
keys or fills yet, but merely as dressing lights. On location, spots still
tend to be HMIs (HID) and soft Kinoflows etc which are basically
fluorescents. But perhaps I only work on low budget stuff. ;-)
In studios, where size, heat and power consumption ain't an issue, halogen
still rules. Apart from dressing lights.

Look at a traffic light next time you're near one. Increasingly they are
LED. The colour stability on traffic lights is very carefully
controlled. Same with large displays such as motorway matrix signs,
imagine what a PITA it was when they were incandescent bulbs.

Traffic signals are especially favorable to LEDs, since most LEDs
specialize in producing colored light while incandescent lamps can have
about 2/3 or a bit more of their output removed by filtering to
appropriate shades of red or green. Also, please consider that traffic
signal incandescents are less efficient than usual household incandescents
due to compromise for designing for long life expectancy and vibration
resistance. Furthermore, LEDs, especially with add-on optics, can more
easily than traditional incandescent-related optics be tailored to waste
less light by shining less light into directions where the requirement is
less or nonexistent.

This should account for why red and green traffic signals were able to
acheive energy savings of 90% (or slightly less) even when white LEDs had
luminous efficacy hardly exceeding that of 100 watt 750 hour 120V
household lightbulbs. And please note that it is recent news for
available (maybe available soon) white LEDs to do much better than that,
and still have luminous efficacy below that of most compact fluorescents.

Some details in: http://www.misty.com/~don/lede.html

- Don Klipstein )

In article ,
(Don Klipstein) writes:

Traffic signals are especially favorable to LEDs, since most LEDs
specialize in producing colored light while incandescent lamps can have
about 2/3 or a bit more of their output removed by filtering to
appropriate shades of red or green. Also, please consider that traffic
signal incandescents are less efficient than usual household incandescents
due to compromise for designing for long life expectancy and vibration
resistance

Although Don, note that they have been LV halogens for at least
last 20 years in the UK, often with programmed current drivers,
and not mains lamps like in the US.

--
Andrew Gabriel

Dave Plowman (News) wrote:

I'm curious - as a sound engineer - in that I've not seen them replacing
keys or fills yet, but merely as dressing lights. On location, spots still
tend to be HMIs (HID) and soft Kinoflows etc which are basically
fluorescents. But perhaps I only work on low budget stuff. ;-)
In studios, where size, heat and power consumption ain't an issue, halogen
still rules. Apart from dressing lights.


I'd not argue, but I think they are comming on, and we won't have to
wait too long to see them breaking into the market in more general
applications. Wait & see...

"Don Klipstein" wrote in message
...
In article , Mike wrote:

"Steve Firth" wrote in message
. ..
wrote:


They are excessive cost, low light quality, rapid deterioration of
output, and the fact that there are much better technologies around.

Funny, in the work I do LEDs are replacing incandescent at one heck of
a
pace because the problems you mention are non-existent (indeed colour
stability with LEDs is better) and service life is much greater.


Agreed - I think the worst case LEDs are 50k hours - about 5 to 50 times
the
life of an incandescent or CFL.

Actually, for white LEDs at full power 50K hours is the high end of
claims not easily "shot down". White LEDs have a problem with phosphor
deterioration, which is not a problem with colored LEDs.

As for actual life expectancy of white LEDs - I have heard enough
figures anywhere from 6K to 50K hours for good ones! Less if you push
them or do not keep them cool!

- Don Klipstein )

From what I hear about led traffic lights:
a) the amber & green colors are incorrect and (particularly the ambers)
drift about with temperature .
b) the output falls out of spec with time.
c) a) & b) are ignored.

Is this true?
Does anyone measure them ?

In article ,
Steve Firth wrote:
I'm curious - as a sound engineer - in that I've not seen them
replacing keys or fills yet, but merely as dressing lights. On
location, spots still tend to be HMIs (HID) and soft Kinoflows etc
which are basically fluorescents. But perhaps I only work on low
budget stuff. ;-) In studios, where size, heat and power consumption
ain't an issue, halogen still rules. Apart from dressing lights.

Look at a traffic light next time you're near one. Increasingly they are
LED. The colour stability on traffic lights is very carefully
controlled. Same with large displays such as motorway matrix signs,
imagine what a PITA it was when they were incandescent bulbs.

But non of these require continuous spectrum light. LEDs are brilliant
at single colour signal lights, as the efficiency is high - and they also
provide a degree of directionality which might be lacking in other types
without a reflector which further aides the perceived efficiency.

However, my gut feeling is that they are a *long* way off from providing
a decent replacement to halogen in a domestic environment for those who
want a 'pleasant' natural light.

Of course, not all care. ;-)

--
*If you remember the '60s, you weren't really there

Dave Plowman London SW
To e-mail, change noise into sound.

(Steve Firth) wrote in
:

No they are not. The wavelengths produced by red, green and yellow LEDs
are incorrect for use in traffic signals, and the colpour shifts
encountered in these LEDs made their use extremely difficult to
implement. It is only (relatively) recently that the problems have been
overcome.

Having noticed that their colour isn't quite the same as 'traditional'
traffic lights, I did wonder if it would be sensible to take the
opportunity presented by their introduction to change their shapes as well?
We are familiar with the octagonal STOP signs - so why not red octagon,
amber triangle and, umm, green circle?

--
Rod

www.annalaurie.co.uk

In message , Rod Hewitt
writes
Having noticed that their colour isn't quite the same as 'traditional'
traffic lights, I did wonder if it would be sensible to take the
opportunity presented by their introduction to change their shapes as
well? We are familiar with the octagonal STOP signs - so why not red
octagon, amber triangle and, umm, green circle?

Have you noticed that the UK LED lights have a full size LED panel
behind the pedestrian crossing "walking man" cut-outs. By contrast in
France the LEDs form the shape of the character.

--
Clive Mitchell
http://www.bigclive.com

In message , R.Lewis
writes
From what I hear about led traffic lights:
a) the amber & green colors are incorrect and (particularly the
ambers)
drift about with temperature .
b) the output falls out of spec with time.
c) a) & b) are ignored.

Is this true?
Does anyone measure them ?

From what I _see_ of the lights around Glasgow, the red is red, the
amber is amber and the green is green. They are much brighter than
traditional halogen lamp versions and emit in a very controlled area as
is the style of LEDs.

I like 'em.


I know that green is supposed to be a particularly bluey green to avoid
colour vision problems, but is this really apparent with the LED lights?

--
Clive Mitchell
http://www.bigclive.com

"Rod Hewitt" wrote
| Having noticed that their colour isn't quite the same as
| 'traditional' traffic lights, I did wonder if it would
| be sensible to take the opportunity presented by their
| introduction to change their shapes as well?
| We are familiar with the octagonal STOP signs - so why
| not red octagon, amber triangle and, umm, green circle?

Using LEDs you could have a little animated car chugging on the green. Would
be great for pedestrian crossings -- a stationary red man could change to an
animated walking green man.

Owain

R.Lewis wrote:

From what I hear about led traffic lights:
a) the amber & green colors are incorrect and (particularly the ambers)
drift about with temperature .
b) the output falls out of spec with time.
c) a) & b) are ignored.

Is this true?

Partially. When LED traffic signals were in their infancy the specs
were all written around incandescents and so didn't address
characteristics particular to LEDs such as intensity and color drift
over time. The Institute of Traffic Engineers (ITE) just released a
Draft of a proposed spec (although it may now be final) for LED Traffic
Signal Heads for US roads. I don't know what's in effect for Europe, etc.

As for existing LED traffic heads - a number of them are
color-compliant, but there are also a number that are close but do not
fall within the established color parameters (and some that are nowhere
near close). My opinion is that the purchasing agencies ignored or were
not aware of the lack of compliance and went ahead because of the energy
and maintenance savings.

Does anyone measure them ?

My company does as a compliance laboratory. We could (but don't)
measure them in the field. It's VERY expensive.

--
Douglas Cummins
Calcoast - ITL

On Mon, 21 Feb 2005, Douglas G. Cummins wrote:

When LED traffic signals were in their infancy the specs were all
written around incandescents and so didn't address characteristics
particular to LEDs such as intensity and color drift over time. The
Institute of Traffic Engineers (ITE) just released a Draft of a proposed
spec (although it may now be final) for LED Traffic Signal Heads for US
roads. I don't know what's in effect for Europe, etc.

Europe doesn't have the glaring-green problem we've got in North America,
'cause their LED traffic signals have variable intensity that dims and
brightens with ambient light conditions. I'll be very surprised if any
glare-control measures at all made it into the ITE spec; glare is
generally ignored (dismissed as a non-problem) in North America.

DS

Daniel J. Stern wrote:

Europe doesn't have the glaring-green problem we've got in North America,
'cause their LED traffic signals have variable intensity that dims and
brightens with ambient light conditions. I'll be very surprised if any
glare-control measures at all made it into the ITE spec; glare is
generally ignored (dismissed as a non-problem) in North America.

DS
Just like global warming and the lack of WMD. (Our politicians got the
last bit wrong too!)

Clive Mitchell wrote:

Have you noticed that the UK LED lights have a full size LED panel
behind the pedestrian crossing "walking man" cut-outs. By contrast in
France the LEDs form the shape of the character.

You are kidding? Please tell me you are...


(Is this "Big" Clive of the "Bam "Board" & the "Electrocutioner"
(http://www.emanator.demon.co.uk/bigclive/halogen.htm)?

Daniel J. Stern wrote:

On Mon, 21 Feb 2005, Douglas G. Cummins wrote:


When LED traffic signals were in their infancy the specs were all
written around incandescents and so didn't address characteristics
particular to LEDs such as intensity and color drift over time. The
Institute of Traffic Engineers (ITE) just released a Draft of a proposed
spec (although it may now be final) for LED Traffic Signal Heads for US
roads. I don't know what's in effect for Europe, etc.


Europe doesn't have the glaring-green problem we've got in North America,
'cause their LED traffic signals have variable intensity that dims and
brightens with ambient light conditions. I'll be very surprised if any
glare-control measures at all made it into the ITE spec; glare is
generally ignored (dismissed as a non-problem) in North America.

New spec has maximum permissible luminous intensity not to exceed three
times the minimum required peak intensity. Also allows the option of
nighttime dimming so long as it does not drop below 30% the minimum
maintained luminous intensity (in other words, can be variably dimmed
dependent on ambient light). Also, luminance across the entire lens
must be uniform, not exceeding a max to min ratio of 10 to 1.

So glare is not ignored - it just wasn't considered previously because
when it was just incandescent traffic signals no one was going to make
their lamps too bright due to heat and energy cost issues. It just
takes longer for the specs to catch up. Now that there's a
specification in place, it's up to the municipalities to make sure their
existing stock and/or new stock meet the published requirements.

--
Douglas Cummins
Calcoast - ITL

In message , Andrew Chesters
writes
Have you noticed that the UK LED lights have a full size LED panel
behind the pedestrian crossing "walking man" cut-outs. By contrast in
France the LEDs form the shape of the character.

You are kidding? Please tell me you are...


(Is this "Big" Clive of the "Bam "Board" & the "Electrocutioner"
(http://www.emanator.demon.co.uk/bigclive/halogen.htm)?

Why yes I am the Big Clive of aforementioned electrical stupidity.

Yes here in Glasgow they use a generic LED illumination panel and just
mask off the unwanted LEDs. Seems a bit wasteful to me, but obviously
it keeps the PCB count low. One PCB does all the graphic stuff like
walking-men and arrows.

--
Clive Mitchell
http://www.bigclive.com

In message , Owain
writes
Using LEDs you could have a little animated car chugging on the green.
Would be great for pedestrian crossings -- a stationary red man could
change to an animated walking green man.

Likewise you could replace the red "don't walk" man with the green
"walk" man being hit by a yellow car with animated LED blood spray.

--
Clive Mitchell
http://www.bigclive.com

Always liked the East German Ampelmann, but Belgium has a particulary
swinging illustration as well:

http://www.ampelmann.de/html/international.html

Adam

In article , R.Lewis wrote:

From what I hear about led traffic lights:
a) the amber & green colors are incorrect and (particularly the ambers)
drift about with temperature .

I thought Daniel Stern told me a few years ago that ITE calls them
yellow and not amber...

Meanwhile, all the red and yellow ones surely look in spec to me for
color, whether LED or incandescent.
Maybe a few yellow LED ones are barely out of spec in the direction of
orange in hotter conditions mainly in unusual conditions such as "on
flash" or stuck on yellow... Easy enough now to avoid now that at
least some LED manufacturers are putting yellow LEDs into color ranks
and one can order a color rank that stays in spec if it goes a bit
orangish from baking in Arizona sunshine in July.
Then again, yellow LED traffic signals are not used much yet because it
is harder (more expensive) to meet the specification for brightness and
the duty cycle is so low that energy savings from using LEDs is not much.

Some green ones appear to me off spec. Some LED green ones appear to me
too pure green, and I see a fair number of incandescent green ones that
appear too lime green.
But it is now easy enough getting "blue-green" or "traffic signal green"
LEDs whose color is in spec.


Now I see a draft proposed standard by ITE for LED traffic signals:

http://www.ite.org/standards/VTCSH_L...ignal_Supp.pdf

Proposed color requirements there are different from the existing ones.
Fairly to really pure reds with dominant wavelength longer than about 632
nm would not meet this one despite (at least as far as I thought I knew)
meeting the current spec. The limit towards orange is roughly 620 nm.
And I have seen enough red traffic signals, both incandescent and LED,
that are more pure red than "HeNe laser red" is.
The new proposed one for LED traffic signal green appears to bar shades
of green with dominant wavelength over about 505 nm, and the old one now
looks to me to allow whiter but not much longer dominant wavelength
unless whiter than traffic-signal-green LEDs. I see a few green LED
traffic signals that appear to me to have dominant wavelength around 510
nm, and I see quite a few incandescent green traffic signals that appear
to me to have dominant wavelength around 520 nm and a few incandescent
ones at least 525 and appearing a bit too "lime green" (as opposed to
whitish) to meet the spec...

http://literature.agilent.com/litweb/pdf/5964-9176E.pdf has the CIE
chromaticity diagram with the existing ITE specification color regions
shown, but lacking wavelength as well as X/Y notations.

---------------------

I have tried making the color of yellow and traffic-signal-bluish green
LEDs vary with temperature, and they don't do so much unless the
temperature gets truly unreasonably high.

b) the output falls out of spec with time.

Eventually... And some drivers are waiting for some of those green ones
to fade!

I have yet to see any LED ones fade from adequately bright to
inadequately bright without being replaced at least as hastily as burnt
out incandescents are replaced.
Although I have seen a small number of LED red ones that had partial
failure to the point of being non-uniform to an extent that is out of spec
while being definitely adequately visible as "a red light", and seen them
take longer to be replaced than burnt out incandescents, and then only in
one municipality that has been mentioned a bit as "the city that doesn't
work"... Furthermore, most of those were ones that I suspect to be pilot
program test units - the odd partial failures were on a specific street or
two where I noticed a pilot program of some sort apparently for testing
LED red traffic signals. And given how much electricity cost they saved
the city (along with probably one relamping halfway through that
incandescents would probably require, with labor cost at big USA-rustbelt
city union rates) over the roughly 5 years they lasted, I would think even
these flunkers were better than incandescents!

- Don Klipstein )

On Tue, 22 Feb 2005, Douglas G. Cummins wrote:

surprised if any glare-control measures at all made it into the ITE
spec; glare is generally ignored (dismissed as a non-problem) in North
America.

New spec has maximum permissible luminous intensity not to exceed three
times the minimum required peak intensity.

H'mm. That's certainly a start...

Also allows the option of nighttime dimming so long as it does not drop
below 30% the minimum maintained luminous intensity (in other words, can
be variably dimmed dependent on ambient light).

OK, that's definitely going to help...IF manufacturers implement
it/municipalities specify it.

Also, luminance across the entire lens must be uniform, not exceeding a
max to min ratio of 10 to 1.

It will be interesting to see what kind of influence this exerts on the
design of the lamp heads. It may tend to reinforce the current North
American practice of using a matrix of many emitters, it may clear the way
for the highly optical Swedish(?) units with only *TWO* emitters per lamp
head, or it may exert no influence at all.

Now that there's a specification in place, it's up to the municipalities
to make sure their existing stock and/or new stock meet the published
requirements.

H'mmm. I can't see it happening too quickly, I'm afraid. Not with the
large number of recently-installed non-spec units.

DS

On Wed, 23 Feb 2005, Don Klipstein wrote:

From what I hear about led traffic lights:
a) the amber & green colors are incorrect and (particularly the ambers)
drift about with temperature .

I thought Daniel Stern told me a few years ago that ITE calls them
yellow and not amber...

Don't think it was I. I am not very familiar with ITE's lexicon. SAE calls
turn signals "yellow", while ECE member countries squabble over whether it
should be "Jaune auto" ("automotive yellow") or "Ambre", or the equivalent
terms in English.

Meanwhile, all the red and yellow ones surely look in spec to me for
color, whether LED or incandescent.

I keep hearing that yellow traffic signals don't "yet" meet standards,
but haven't yet heard a satisfactory explication of the noncompliance, and
I do see yellow wafers going up. Slower than reds and greens, 'cause the
payback time is longer, but I *do* see them.

And, as I've mentioned here before, Ontario uses 2-color LED heads for the
schlock green arrow that then changes to a yellow arrow (same lamphead,
same arrow, just a color change).

DS

"Clive Mitchell" wrote
| Using LEDs you could have a little animated car chugging
| on the green.
| Would be great for pedestrian crossings -- a stationary
| red man could change to an animated walking green man.
| Likewise you could replace the red "don't walk" man with
| the green "walk" man being hit by a yellow car with
| animated LED blood spray.

Chewin the fat You've taken that too far you have.

Owain