The Great White Hope (Pre Project Thread)

[manuellynch]

As digital media useage increases along with the desire for thinner light boxes a lot of LED systems are coming into the market for backlight.

This is a question that probably deserves another thread - but, does neon, fluorescent, or LED at the exact same color temperature render images differently?

Would like some feedback on rendering digital images with various different light sources.

[YYZ]

Actually, years ago, 4500 was de rigue, or whatever . It was the standard, then 6500 come along and took over the world, and now 71 is preferred by many. The choices of white often make a major difference in what is percieved, yet I would say that YYZ comments that 4500 does nothing for some colors is a stretch.

gn

Actually, what I said was that anything between 3500-5500 would work well for a broader color spectrum than 6500.

I did say that for signs, the warmer colors are seldom used for channel letters, and Manuel pointed out one of the times where they do work quite well. I also said that the 4400-5200 is seldom used, not that it's 'never' used. It's just one of those ranges that manufacturers don't stock as much of since the other color ranks are more popular and/or more efficient at performing certain tasks.

"Neutral White" is making a bit of a comeback (or emergence) on the lighting side of things, since it is a nice medium between cool white and warm white. 4100 is the target for this tone of white, but for my taste, 3500 would be much better. It's warm, but not dirty warm - but this would still not be used much (if ever) for signs. I'm thinking we're going to keep 5300 and 6300 as our stock colors for channel modules, but will have 2700, 3200 and 4100 diodes in stock because we also do lighting and can turn around the special batches within acceptable lead times for most sign projects. I'm moving to a new condo soon and will experiment with lighting the whole place in either 3200 or RGB lighting (for company ;) )

Manuel - as I mentioned - we have done some testing thru partner/customer companies, and 5300k was the preferred backlight temperature.

[whistler]

Generally speaking, 6500k White is common because it's the best compromise between brightness as color quality. The "bluer" you go, the higher the brightness (based on equal power). The "warmer" you go, the lower the light output.

From a usage standpoint, 6500k is on the blue side for most, but not unlike moonlight, which most people's eyes are used to at night - and visual acuity is actually better with a higher k temperature (this is why visibility under metal halide lamps is sharper than under sodium lamps, for example). It's a better color for backlighting blue, purple, etc.

Our 5500 (nominal, usually 5300-5400) is a much nicer "actual white" which I would consider "sign white", as it is closer to the color of a Daylight Fluorescent lamp than 6500k neon, even though a Daylight lamp is actually supposed to be 6300k. My experience is that most neon and/or LEDs that sell as a 6500k are actually cooler, some pushing 7000k and beyond. A white in the 5300-5500 range is still going to give you a nice punchy white, but also be able to backlight pretty much any color in the spectrum, especially brighter colors. It goes right from red to yellow to green to blue with no trouble because of the higher CRI.

Once you get into even warmer colors (the range between 4400 and 5200 is seldom used), your output drops further still, and is useless at illuminating blue, purple, etc. You get nice neutral white (3500 - 4100, like most halogen lamps), what I call designer white (3000 - 3400) and warm white (2600 - 2900) that replicate incandescent light... these are seldom used for illuminating channel letters, but for backlighting a large format images, posters, etc - anything between 3500 and 5500 will do a much better job than 6500k light sources. We're working on a large airport project that is using a 12 color printing process for the digital prints, and 5300k was deemed to be the perfect white source for backlighting.

I agree with the challenges of the darker colors such as blue, green, purple, & burgundy. They're even a challenge with 6500K. But, it offers the best option because of the "blue" in the light.

Plus, I've seen how a warmer white (3500K) seems to work better with the day/night acrylic or film as compared to using 6500K. It doesn't look great but it looks brighter. But, getting the end user to accept it is the challenge and that means samples need to be provided to aid in the decision maing process.

I'm agreeing with you on the use of 5500K for channel letters as I find it more appealing. But, when dealing with the end user it's based on what they want and like which may go against what you are proposing. With that everybody has a different concept which makes it difficult to establish any kind of a true standard. For me just having some guidelines to work with helps in the decison making process and has helped in working with the end user.

[Erik Sine]

Due to the number of slots, I think I may have to reconsider 1 only per vendor putting their best product forward, and maybe going from 8" to 6" on the stroke width, otherwise this cabinet may end up being 8+ feet.

[ZGrajcar]

I got a request from Westcoast SG to submit our LED system (HYPERION R-Lite manufactured by Lumificient Corporation) for white LED performance testing. I do not have problem with it, however we do have to make a rules clear.

1./ Testing Factor 1: You mix units of luminous flux (Lumen) and luminance (nit or cd/m2). You can not measure lumens on the surface. If you are measuring nits (or in metric SI >> candela per square meter) on specified acrylic face surface, you do need to define at what wavelength you will be doing it.

2./ Test Factor 2: Lumens over time is incorrect statment. In your case you measure cd/m2 (nits) over time.

3./ Test Factor 3: Watts per meter? This can be very interesting. Are you sure you want to measure W/m? I can already tell you who will win. Correct measurement is Watts per sign or Watts per channel letter. And this have to include power unit losses and PF factor.

Next thing is that you did not specify any environmental conditions. Will you do "real life" simulation in environmental chamber (hi/lo temp / hi/lo humidity) or you simply put it on your bench and let it run. If it is bench test, your results will be "highly" innacurate. If you are willing to do true environmental test, lets say IEC 60068-2-38 (composite temp/humidity test) and modifications of IEC 60068-2-61 (Climatic sequence), we are in. Not only that. I'm personally willing sponsor this kind of testing.

Two more remarks to previous posts:

- FACT: So called junction temperature is absolute maximum. Crossing that you will go to thermal runaway and destruction of the silicone latice (catastrofic LED failure). LED chip manufacturers spec 80 C as a maximum junction temp for long life performance (at 40% RH).

- FACT: LEDs are most efficant (do not confuse with efficient), meaning lumen per Watt, at mid 5000K range (5400 - 5600K).

[YYZ]

I got a request from Westcoast SG to submit our LED system (HYPERION R-Lite manufactured by Lumificient Corporation) for white LED performance testing. I do not have problem with it, however we do have to make a rules clear.

1./ Testing Factor 1: You mix units of luminous flux (Lumen) and luminance (nit or cd/m2). You can not measure lumens on the surface. If you are measuring nits (or in metric SI >> candela per square meter) on specified acrylic face surface, you do need to define at what wavelength you will be doing it.

Lumens has been used in this discussion since most LED mfrs make their claims in lumens - that's the exact reason why this comparison is being made - so that "lumens" gets converted into a real, measurable number. Erik's test will be illuminance on the surface of the letter. Whether he uses nits, Lux, footcandles - the important thing is to use the same metric for all products. Nits would be the most "proper", but most difficult for sign shops or designers to measure themselves. Using a simple $99 light meter to measure footcandles or Lux is probably better.

2./ Test Factor 2: Lumens over time is incorrect statment. In your case you measure cd/m2 (nits) over time.

Yes. The above should clarify the semantics.

3./ Test Factor 3: Watts per meter? This can be very interesting. Are you sure you want to measure W/m? I can already tell you who will win. Correct measurement is Watts per sign or Watts per channel letter. And this have to include power unit losses and PF factor.

Actually - multiple benchmarks should probably be listed. Watts per metre (or foot), Lux/fc per foot, Lux/fc per Watt, Lux/fc per $$. Since every cavity in this test will be the exact same size, it is essentially a "per letter" comparison and by the sounds of it, external measurements will be made to calculate power unit losses, etc.

Erik - have a look at how the PC magazines do benchmarking tests for laptops and such. There are 5 or 6 categories and each brand is then compared to the others within that category. Different users seek different results (ie: rendering time vs math processing) and the same could be said for sign mfrs. Some will find more value in the cost, others brightness, etc... Each mfr is then given points on their placing in each category, then aggregate scores can be used to grade the systems.

Next thing is that you did not specify any environmental conditions. Will you do "real life" simulation in environmental chamber (hi/lo temp / hi/lo humidity) or you simply put it on your bench and let it run. If it is bench test, your results will be "highly" innacurate. If you are willing to do true environmental test, lets say IEC 60068-2-38 (composite temp/humidity test) and modifications of IEC 60068-2-61 (Climatic sequence), we are in. Not only that. I'm personally willing sponsor this kind of testing.

I can't speak for Erik, but I don't think this comparison was ever intended to meet any IEC guidelines - it's more to make a public comparison of the varying products since anyone who has done this privately has either A) not made the info public or B) not trusted to represent all sides fairly. In that sense, this will be an accompishment even if it is simply a "bench test". It would absolutely be better to test with as many variables as possible - if you're willing to sponsor the costs of doing this then my hat is off to you.

Two more remarks to previous posts:

- FACT: So called junction temperature is absolute maximum. Crossing that you will go to thermal runaway and destruction of the silicone latice (catastrofic LED failure). LED chip manufacturers spec 80 C as a maximum junction temp for long life performance (at 40% RH).

- FACT: LEDs are most efficant (do not confuse with efficient), meaning lumen per Watt, at mid 5000K range (5400 - 5600K).

Yup.

Edited July 8, 2008 by YYZ

[Erik Sine]

Benchmark test is the correct word. 6500 as a standard using #7328 white.

Think of this as an indoor environment shopping center sign.

I'm all for a IEC run but that can get pricey, but would make for one hell of a test!

But I'd like to clear one aspect of this comparison, it's not about overall power consumption and brightness. I think there will be a few surprises along the way.

If anyone has suggestions on other factors to test, please let me know, just know my equipment is limited

[manuellynch]

- FACT: So called junction temperature is absolute maximum. Crossing that you will go to thermal runaway and destruction of the silicone latice (catastrofic LED failure). LED chip manufacturers spec 80 C as a maximum junction temp for long life performance (at 40% RH).

Newer LEDs have a junction temperature max of 150C. Also these LEDs can operate near junction temperature and achieve lifetime performance with 80% humidity. But good luck with the LEDs you are using sir. It is my understanding that you DO NOT use Nichia LEDs. As always - good luck in your business.

[ZGrajcar]

Main reason why I'm proposing IEC test is simple fact - we do not live in perfect world. Sign companies are not asked to do a sign for specifically for Anchorage, AK, Orlando, FL or for Phoenix, AZ. As you can see, those three cities have very distinctive environmental conditions. Phoenix is dry and hot, Orlando humid and hot and I do not have to describe Alaska (or some parts of Canada). So if you are testing it on the bench, you will have 25C and somewhere around 50 RH. I can assure you majority of LED systems will work just fine. Lets elaborate. Take system X where we will use 1W LED driven at 350mA with off the shelf heatsink (majority of high power systems ). Most likely you will measure somewhere around 60 to 80 C on the solder joint. This will give you temperature rise Tsa 45C (avg 70C – 25C ambient). If your thermal resistance between junction and solder point is let’s say 10C per Watt, and you are running your lLED at 1.25W (350mA x 3.5V), then your temperature rise junction to ambient is at (1.25W x 10C/V)+45C = 57C. Now comes interesting part:

1./ Benchtop test at 25C ambient: T LED junction = 57C + 25C = 83C >>> Result: good performance, good life, good system

2./ IEC test at 60C ambient: T LED junction = 57C + 60C = 117C >> Result: poor performance, very short life (>5000h), very bad system

3./ IEC Test at 80C ambient: T LED junction = 57C + 80C = 137C >> Result: thermal runaway on junction level, catastrophic failure

FACT: Temp inside channel letter, in fact, can go much higher than 80C. Temperatures over 60C are very common in the sign industry (even at 11pm) and account for more than 20% of operating time of the sign (average). In AZ, it is more than 50%.

Should I continue with more “LED Truth” ?

[manuellynch]

FACT: Temp inside channel letter, in fact, can go much higher than 80C. Temperatures over 60C are very common in the sign industry (even at 11pm) and account for more than 20% of operating time of the sign (average). In AZ, it is more than 50%.

Should I continue with more “LED Truth” ?

I live in Las Vegas Zdenko - we know a thing or two about heat. And in Australia, Dubai, and India where we also sell quite a bit of product we see similar extreme conditions. 10C/W seems high...you should ask for better. And you may also want to check micro via technology used in power amplifiers for thermal conduction. And I did tell you I did work for one of the largest military/satellie semiconductor manufacturers...didnt I? Temperatures can get pretty extreme in these applications. Do you want more on the "Thermal Truth"

[ZGrajcar]

As always, Manuel is using this board for marketing purposes only and also for wicked attacks against his competitors (even against the company he was leading for years). Get your facts straight, please.

First, we do, in fact use Nichia dies and Nichia phosphor (read carefully). If you do not believe, call Dan Doxsee at Nichia and ask him.

Second, show me one document, just one confirming your junction temperature statement. And do it publically on this board. I know for fact that non of the LED manufacturer will publically state that at near maximum junction temperatures (120C or 150C for some Lumileds) and 80RH their product will have long life performance (50000 hours plus). My friend, this just shows that you do have limited knowledge in semiconductors and silicon lattice structures. And please stop using this board as a free advertisement for your products.

[ZGrajcar]

Correct me Manuel, because I may be wrong on this one. Didn’t you work there in marketing/ new business development?

I have to give you this one. You are very, very good marketing person. I do not say it sarcastically, I really do mean it. Marketing is what I really do suck in and I can recognize good marketing person.

But please do not spread false engineering (and scientific) information. It is hurting both of us. Guys reading our blocks do need to know facts.

[manuellynch]

As always, Manuel is using this board for marketing purposes

I am sorry I do this better than you Zdenko.

First, we do, in fact use Nichia dies

Now that is really funny. No one can purchase their dies...are you that special?

If you do not believe, call Dan Doxsee at Nichia and ask him.

Oh I will - I would love to purchase Nichia die. I will have him jump on here and correct that for the group.

Second, show me one document, just one confirming your junction temperature statement. And do it publically on this board. I know for fact that non of the LED manufacturer will publically state that at near maximum junction temperatures (120C or 150C for some Lumileds) and 80RH their product will have long life performance

I will find the Nichia lifetime curve at these elevated temperature and humidity and post it for you and for the members of this board.

And for the record - my advertising isnt Free - I like YYZ pay for our ads on this site. Why dont you?

[ZGrajcar]

I am sorry I do this better than you Zdenko.

Now that is really funny. No one can purchase their dies...are you that special?

Oh I will - I would love to purchase Nichia die. I will have him jump on here and correct that for the group.

I will find the Nichia lifetime curve at these elevated temperature and humidity and post it for you and for the members of this board.

And for the record - my advertising isnt Free - I like YYZ pay for our ads on this site. Why dont you?

[ZGrajcar]

Well again. Get your facts straight. We do use Nichia dies and phosphor. I newer said we are purchasing it from Nichia. I can disclose who is packaging it, but that will not be very smart business move to do it publicly. But once you bring Dan from Nichia on board, he will make it straight and prove you wrong. As for junction temp vs life, show me the documents and I will publicly apologize to you. I know you cannot produce them.

[Erik Sine]

Okay here is what I have for slots at 8" x 3'

Individual Slots

• 6500 white 15mm (The Project Standard)
  
• EGL CL71
  
• Elite Tri-65D
  
• Eurocom
  
• YYZ LED Line
  
• Axiom LED Line
  
• Agilight LED line
  
• Sloan LED Line
  
• Phillips LED
  
• GE LED Line
  
• Lumificient LED Line
  
• US LED
  

Am I missing anyone? I don't reall want to make this cabinet to huge it's 80"+ right now

Thank you for correcting me Zdenko, I think it was mentioned to me before but I wasn't paying attention. So we will be measuring nits, on the sign panel of #7328 white with a foot candle meter. (right? )

[manuellynch]

So we will be measuring nits, on the sign panel of #7328 white with a foot candle meter. (right? )

You might do a "Real Person" test as well. I think most in the sign industry will confirm that whether we like it or not it is the "visual" test that usually determines what is used.

[Erik Sine]

That is true, I think the biggest part of this test will be individual perception. Even though a product is "brighter" doe not mean it is appealing, same can be said for power consumption.

[manuellynch]

That is true, I think the biggest part of this test will be individual perception. Even though a product is "brighter" doe not mean it is appealing, same can be said for power consumption.

I agree with you on this. Even of our parts are 80% less power than neon it doesnt mean that neon may be the better choice for a purple face sign.

And get different age range of viewers - someone 20-30, someone 30-50, and someone over 50. Eyes change with time - light meters dont...sorry...but it is people that make decisions on what to use.

[YYZ]

First, we do, in fact use Nichia dies and Nichia phosphor (read carefully). If you do not believe, call Dan Doxsee at Nichia and ask him.

If you use Nichia chips and Nichia phosphors, it does not make it a Nichia "LED" and - in my opinion - it is misleading for you to use the "Genuine Nichia LED" logo in your literature. When people see this, they expect a Nichia-made LED, not some quasi version. Nichia has a failure rate of about 1 in 20 million and this is what people pay for when they buy a "Genuine Nichia LED".

For example, we use a fair bit of Nichia product, but also have a package made for us using Cree chips and Toyoda Gosei phosphors - but we don't claim that they are Cree or TG LEDs - because they're not.

You and I got on Manuel's case about the wording around the 100LPW LEDs, but this is even worse IMO. Better to just not say which LED it is, but I suspect you know full well that namedropping Nichia like this makes your product look better than it is.

Edited July 11, 2008 by YYZ

[Erik Sine]

Updated now to a 8' long cabinet adding Eurocom's "Cold Cathode" and LED Line making a total of 12 slots

[imanut]

Updated now to a 8' long cabinet adding Eurocom's "Cold Cathode" and LED Line making a total of 12 slots

And what is so special about Eurocom's "cold cathode", and why in parenthesis????

gn

[Erik Sine]

Just doing my part in loosing "Neon" and Using "Cold Cathode"

[imanut]

Just doing my part in loosing "Neon" and Using "Cold Cathode"

Okay, so with taht being clarified----why bother comparing eurocom with elite or EGL??? YOu comparting trodes also, or the gas, or just see if B.S. matches the hype????

gn

[Erik Sine]

Okay, so with taht being clarified----why bother comparing eurocom with elite or EGL??? YOu comparting trodes also, or the gas, or just see if B.S. matches the hype????

gn

:Chew: *shrugs* I dunno, they offered, I'm graciously obliging.

I think it would be interesting to see how different manufacturer's coatings holds up as well, don't you? There are other neon guys that should be here as well, but what can I say? I'm not going to beg anyone. Besides, I don't think of this benchmark as just LED vs Neon anyway.

Whoever wants to throw their light source in, by all means, let's have it! When it comes to the neon industry I get tired of the last man standing attitude that some manufacturer's seem to have. So if their here to offer help, interact, instead of just lurking as usual, then that's encouraging news to me.

Because with the neon crowd, I have never watched a more self collapsible group, you would almost think they were double jointed.