# Combining LED light with other light sources



## Anders Hoveland (Sep 1, 2012)

465nm blue LED's are very efficient light sources, but their light output is only a single color frequency in the spectrum. Using a typical yellow phosphor coating, the output can be expanded into the green-yellow-orange spectrum, but at the cost of reduced efficiency. In other words, the more yellow a white LED is, the less bright it will be for a given input power. "Cool white" LED's are typically 40-65 lumens/W, whereas "warm white" LED's are only around 35 lumens/W.

Incandescent bulbs give off broad spectrum light more shifted towards the yellow-red spectrum. 

One big disadvantage of incandescent light is that it is deficient in the bluer frequencies of the spectrum, and so appears much more yellowish. For the same reason, incandescent bulbs are not as good as bringing out the color contrast of blue colored objects in a room. In an attempt to address this drawback, "Reveal" bulbs are being marketed, with a neodymium filter coating the inside of the bulb which filters out most of the yellow light. Unfortunately, this does not really entirely solve the problem, and causes other drawbacks. A significantly undesirably ammount of the blue light also gets filtered out along with the yellow, contributing the original problem the filter is designed to compensate for. This also leaves a small yellowish-green peak in the spectrum, so the light from Reveal bulbs can appear a little greenish. And filtering out all the yellow light, along with some of the blue-green, negetively affects the light's ability to accurately render different colors. Filtering out light also greatly reduces the efficiency producing light.

Low pressure sodium discharge lamps give of a narrow frequency of yellow light at around 589nm. These are much more efficient light sources than even LED's, with typical ratings around 160 lumens per Watt. Unlike fluorescent and other gas discharge lights, low pressure sodium does not contain any mercury, and so does not give off any UV radiation that some individuals are negetively sensitive to. But sodium lamps take around 5 minutes to warm up after initially being turned on until they can really begin producing light. And low pressure sodium lamps only produce yellow light, which is undesirable or unsuitable for many settings.

So my thought is, why not combine LED light with another light source, either incandescent or low pressure sodium?

Low pressure sodium is often not used since it gives off only yellow light. But ironically, much of the efficiency of blue LED's is lost in trying to add yellow light to it's light output. Why not combine the two? Very high efficiencies could be achieved. Another irony is that many street lamps use _high_ pressure sodium discharge tubes to try to produce a few other colors of light, but much efficiency is sacrificed just trying make the light a little more whitish (high pressure sodium lamps contain mercury, have very orange harsh colored light, and have values around 110 lumens per watt). LED lights are just good at producing blue light, and sodium lamps are just good at producing yellow light. When one tries to make simple adjustments to make either of these lamps give off a little of the other color of the light, the efficiencies greatly suffer.

LED lights and sodium vapor lights are both already widely used for outside floodlighting. Usually these outside LED lights are "cool white", because it is less efficient to convert much of the blue light into yellow. Pure blue LED lights, or low pressure sodium vapor lamps are rarely used. Despite the higher efficiencies of these two, all blue light or all yellow light is regarded as less desirable. But why not combine the two together? Blue LED's and low pressure sodium, each producing their own respective part of the spectrum they are most efficient at, instead of either one individually being adapted to produce a little of the other color they are not so efficient at. By combining the two types of light together (598nm yellow and 465nm blue), a pure white appearing light would be possible, and could be produced with very high efficiency.

There would be some technical problems though. High powered LED lamps need to be cooled (either with a large heat sink or fan), while the sodium discharge lamp would be given off heat. It may be better to have two separate housings for the two types of light, so as not to interfere with cooling the LED. But then the two light outputs somehow have to be combined if it is desirable to give the appearance of a white light source, instead of two different colored lights. The downside of this color combination is that the color rendering ability of such a hybrid would not be as good as a warm white LED because the yellow from the sodium light source is a narrow frequency, whereas the yellow light from the LED's phosphor coating is a much wider band of frequencies. But this would not matter so much for outside commercial/street lighting.

Or for inside lighting, cool white LED's could be combined with halogen bulbs. This could still match the efficiency of fluorescent light, but have a far better quality of light, without harshness and with better color rendering. Incandescent lights (including halogen) are full spectrum but deficient in blue light, so it makes sense to combine them with LED light, which has plenty of blue light but whose color frequency output is not as balanced across the spectrum.

Another option could be to use a red LED together with a "neutral white" colored LED (with equal ammounts of blue and yellow light). Red LED chips are rated 25 lumens per Watt, a little higher than halogen. The red LED would help fill in the part of the spectrum where the green-yellow-orange band of the LED phoshor is deficient, both giving a "warmer" feel to the light and improving color rendering ability. In terms of making a white LED a "warmer color temperature", it may be more efficient to use a combination of the yellow phosphor a_nd _an outside red LED. Since red is "warmer" than yellow-green, it takes less red light to give the lamp a warmer color temperature than the ammount of blue light that would have to be converted to the yellow band. Even though the red LED is 25 lumens/W, less than the 35 lumens/Watt of the yellow phosphor, it could allow a larger proportion of blue light to be used, which is by far the most efficient. Of course there does need to be some yellow light. If we only used a blue LED and a red LED, the combined light would look purple (magenta to be technical).

Why is this type of combination never used? Is it just something no one thinks about? It seems often people just want to choose one light source or the other for simplicity, and do not realise the advantages of combining two different complimentary light sources.

Color science and the tradeoffs in efficiency and light quality are very complex, but I feel we would all have better light sources if we understood it better.


Also, I wanted to add one more thing. Incandescent bulbs are also not as "inefficient" as is widely claimed. Let's make one thing clear: lumens per Watt is not a true measure of efficiency. One big reason why LED's typically have higher lumen ratings is that LED's are _*directional*_ light sources. While incandescent bulbs will typically give off their light equally in all directions, light from an LED tends to be much more concentrated in one direction. Lumens per watt is a measure of light intensity _within a given angle_. And what angle is used to measure an LED source? If the measurement is made towards the backwards sides of the LED, the lumens per watt will be much lower. The light from the LED is more concentrated, so has a higher lumen rating. Halogen lights, when used with a reflectors in the form of a floodlight, also have higher lumen ratings. This is different from light output. Obviously using a 100 watt floodlight is not going to light a room better than than a similar 100 watt bulb that is not a floodlight. Because of this, one of the ironic things about most LED bulbs is that they _*appear*_ brighter but often actually provide _*less*_ light illumination to the room. Add in the fact that heat output can be desirable in colder climates (and at night when it is cooler and lights are most typically used) and there might not really be so much justification for switching to "energy efficient" lighting.


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## SemiMan (Sep 2, 2012)

I am sorry, but I do not think there is any way I can say this nicely. I think you need to do a significant amount of reading and research and then ask again. Actually if you do said reading and research, you will not ask these questions as you will know the flaws in so many of the arguments you make and things you state as "fact" that are wrong. I would not even know where to start.

To start, it is obvious you don't know what a "Lumen" is though you use it regularly. Start by learning that. It will make you realize the fallacy of much of what you wrote.

Then I would read up on the state of the art for LEDs.

Somewhere along the way you could learn why mixing RED LEDs with other LEDs is good for improving color rendering while increasing efficiency as opposed to using phosphors. 

My post may seem mean, but you are posting things like they are fact without doing some basic research to know if you understand what they heck you are talking about ......








Anders Hoveland said:


> 465nm blue LED's are very efficient light sources, but their light output is only a single color frequency in the spectrum. Using a typical yellow phosphor coating, the output can be expanded into the green-yellow-orange spectrum, but at the cost of reduced efficiency. In other words, the more yellow a white LED is, the less bright it will be for a given input power. "Cool white" LED's are typically 40-65 lumens/W, whereas "warm white" LED's are only around 35 lumens/W.
> 
> Incandescent bulbs give off broad spectrum light more shifted towards the yellow-red spectrum.
> 
> ...


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## wrf (Sep 3, 2012)

Anders Hoveland said:


> [...]There would be some technical problems though. High powered LED lamps need to be cooled (either with a large heat sink or fan), while the sodium discharge lamp would be given off heat.
> [...]Add in the fact that heat output can be desirable in colder climates (and at night when it is cooler and lights are most typically used) and there might not really be so much justification for switching to "energy efficient" lighting.



My belief is the main reason combining light types has not been done is the hot/cold compatibility issue you mentioned.

If you will permit some conjecture, I think another reason is the manufacturing cost (even though only a small fraction of end user cost) increases too much for many businesses to approve of this approach. Why put in the materials for two lights to only manufacture one? Sometimes it's all about the expense vs. profit margin. Not saying it's right, just saying it is what I have observed.

As far as the heat benefit, I have electric baseboard heating (as do most residences in my area), and it is on 9 months out of the year. So whatever heat is not produced by lighting is simply made up by more electical usage by the baseboards (which don't give out any light at all). I only benefit from cool lighting about 3 months out of a year.


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## SemiMan (Sep 3, 2012)

wrf said:


> My belief is the main reason combining light types has not been done is the hot/cold compatibility issue you mentioned.
> 
> If you will permit some conjecture, I think another reason is the manufacturing cost (even though only a small fraction of end user cost) increases too much for many businesses to approve of this approach. Why put in the materials for two lights to only manufacture one? Sometimes it's all about the expense vs. profit margin. Not saying it's right, just saying it is what I have observed.
> 
> As far as the heat benefit, I have electric baseboard heating (as do most residences in my area), and it is on 9 months out of the year. So whatever heat is not produced by lighting is simply made up by more electical usage by the baseboards (which don't give out any light at all). I only benefit from cool lighting about 3 months out of a year.




So you don't think it would have anything to do with the optical incompatibility of the multiple light sources + source offset that would make mixing the two sources difficult if not impossible for anything but an inefficient floody light?

Where do you live where a) You would require heat 9 months of the year and b) It would make any economic sense to use electric heating? I live somewhat north and rarely use heat more than 8 months of the year. For the other 8, gas heating makes far better economic sense. If I could not do gas, propane or possibly even oil would be cheaper. There are only a very few places I can think of that have predominantly hydroelectric power where electric heating makes sense. Even that is debatable as it would be far better to use gas for heating and export the electricity to a jurisdiction that would use coal.


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## AnAppleSnail (Sep 3, 2012)

A lumen is a lumen. LEDs are twice as efficient as you cited, excluding driver losses. See their data sheets!Incandescent lights are less efficient for producing visible light than LEDs are. This is because they produce heat, which wastes power. Heating by light bulb is terribly wasteful, since must bulbs are recessed into the ceiling. Most of the heat goes out the roof. Floor heaters use this fact.I applaud you attempting to manifesto lighting synergy technologies. But the needs and gains given by adding filaments or plasma arcs to LED.aren't worth the costs. Red, deep red, and neutral white are excellent for very high color rendition... Without complex double light systems.


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## wrf (Sep 3, 2012)

SemiMan said:


> So you don't think it would have anything to do with the optical incompatibility of the multiple light sources + source offset that would make mixing the two sources difficult if not impossible for anything but an inefficient floody light?
> 
> Where do you live where a) You would require heat 9 months of the year and b) It would make any economic sense to use electric heating? I live somewhat north and rarely use heat more than 8 months of the year. For the other 8, gas heating makes far better economic sense. If I could not do gas, propane or possibly even oil would be cheaper. There are only a very few places I can think of that have predominantly hydroelectric power where electric heating makes sense. Even that is debatable as it would be far better to use gas for heating and export the electricity to a jurisdiction that would use coal.



1) Lots of uses for floody light, but your point is valid. I simply don't consider it to be a primary obstacle unless you are creating spotlights.

2) Gas availability limited and very expensive, and gas leak explosions have resulted in a very tarnished "safety" record. Propane very expensive and only in limited use in outlying areas. Some very old (orginally farm) residences have oil, but again very limited. Electric is the norm here. Modern office buildings often use heat pumps, but offices where I'm at often fail to maintain the temperature due to lack of capacity (and proper maintenance).
I grew up in areas that were predominantly central gas heat. I didn't even know central electric heat existed until I moved here. Doesn't matter what I or anyone else thinks -- it's just the way it is here.


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## blasterman (Sep 3, 2012)

In all fairness the OP has some interesting concepts, but some of his comments are so out-dated I assume the flux capacitor in the Delorean must be out of juice.



> Red LED chips are rated 25 lumens per Watt



Last time I checked pretty much everybody was at 75-80 lumens per watt at 625nm. Also, white LEDs don't use 465nm as a dominant blue wavelength. 450nm is more common.

LPS and HPS have higher efficacy than LED currently does in the orange region, but typically it takes several hundred watts to reach those conversion levels. A hybrid LPS / solid state source sounds intriguing, but mixing the light sources would be daunting, if not impossible.

Not sure where to start on Incandescent......it's a terribly inefficient technology no matter how you look at it. 100-watts of even the highest efficacy HIR halogen will produce orders of magnitude less lumens than 100watts of 2700k-3000k LEDs that come from good tech. While the LED's lack the energy emitted in a full spectrum Incan source it doesn't really matter. You could easily add 475nm and 660 red LEDs to a CREE LR-6 or CR-6 engine and have legitmate full spectrum solid state source and STILL thrash the Incan in terms of efficiency. All it would do is be more expensive and most eyeballs woulnd't be able to tell the difference.


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## SemiMan (Sep 3, 2012)

wrf said:


> 1) Lots of uses for floody light, but your point is valid. I simply don't consider it to be a primary obstacle unless you are creating spotlights.
> 
> 2) Gas availability limited and very expensive, and gas leak explosions have resulted in a very tarnished "safety" record. Propane very expensive and only in limited use in outlying areas. Some very old (orginally farm) residences have oil, but again very limited. Electric is the norm here. Modern office buildings often use heat pumps, but offices where I'm at often fail to maintain the temperature due to lack of capacity (and proper maintenance).
> I grew up in areas that were predominantly central gas heat. I didn't even know central electric heat existed until I moved here. Doesn't matter what I or anyone else thinks -- it's just the way it is here.



Where I live there was the ill conceived electric heat idea back in the 70s. Fortunately that idea died out for numerous reasons ... cost being one, but also bad for the environment. Until all coal generation is gone, we can always export "green" production electricity to areas where coal is used. Burning coal to make electricity (or even gas) and then heating with electricity is terribly inefficient compared to a 90% plus efficient gas furnace. Not sure what your comment about safety means, but I can't remember the last time I heard of a gas oriented accident in a private residence where I live and every house is heated with gas here ... and that is a lot of houses. Yes there is the odd leak, but gas explosions are extremely rare.

In terms of LPS/HPS efficiency, we are already at those efficiencies at tolerable currents for 65+ (70 typ) CRI white. I think if one targeted 25CRI, we could beat even LPS with current LED tech.

It would be extremely difficult to mix as the optical sources are so vastly different. You would lose tons of efficiency doing it which would remove any point to do it. Lets not forget different lumen maintenance rates. It just makes no sense if you have a basic understanding of the technologies.

Semiman


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## blasterman (Sep 3, 2012)

> I think if one targeted 25CRI, we could beat even LPS with current LED tech.



Mmm, maybe in the lab, but not currently on the shelf. In order to get more than 100 lumens per watt current production LED's have to sacrifice amber and orange-red, which means 'cool-white' and/or low CRI, correct? Low pressure sodium is insanely efficient at producing 590nm light, but even if we had a theoretical light made from cool-white LED's and LPS we'd still probably need a legitimate red source for a decent spectrum unless we only plan on using it for parking lots, etc. This would negate most of the trouble screwing around with it.

HPS would work better in a theoretical hybrid lamp because it has a broader orange-red spectrum and you wouldn't need additional color augmentation on that end. Still, all of this is a solution in search of a problem as I think we both agree. Plasma is already an option on the high wattage end of things.


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## deadrx7conv (Sep 4, 2012)

If you quit worrying about specific spectrums and nm's, mixing bulbs can make certain lighting 'prettier' and 'more pleasing', especially if certain fixtures are already in place and working acceptably. Adding in that 'other type' of lighting can help and it doesn't even need to cover the 'entire area', or even be in the same fixture. It can also be a backup to when the main bulbs blow. You don't need to cover every possible wavelength. 

I'm trying to be 100% CFL/LED and it isn't working. 

When talking LED, do forget about the over-hyped datasheets. Not every bulb is being produced with the latest greatest binned LED. Even though I laughed at the OP's 1st paragraph, my killawatt meter seems to agree. Until we have 99% efficiency LED drivers and optics, we're lying to ourselves. 

Hopefully the tech, in the L-prize winner and its competitors, find its way to all other bulb sizes and types, along with a substantial price drop and bump in 'cool' feeling(kelvin). It just isn't happening quick enough. Not enough L-prized equivalents in the marketplace, especially in 25w, 40w, 75w, 100w and all the PAR sizes. Will remote phos be the future? It only took about 10 years to come out with just one LED bulb that is acceptable, which is now finally in stock, and seriously overpriced. http://www.lightingprize.org/60watttest.stm

I also have bulbs that switch back to incan from CFL/LED in certain areas for the 'heat'. Electric heat is pretty common around here. And, even if gas/oil heat was used, the thermostat might just cycle a few times less during the entire winter too. So, during the winter, the inefficiency of the 'incan' is over-hyped for areas that require heating. Not all the bulb heat is dumped thru a drafty recessed can fixture into the ceiling/attic especially if you don't have or care to use recessed cans. They lied to you, and you were caught hook/line/sinker!

In the summer, the CFL/LED is less of a hassle since I'm outside more and don't miss the CRI! The summer efficiency of the CFL/LED is greater than advertised if the A/C cycles a few times less during the summer. You'll save on your cooling cost too....the "not as hot bulb wattage syndrome" was always mentioned. Feeling brainwashed toward CFL/LED yet? 

During the short winter days if you spend sunrise:sunset in a fluorescent tube lit workplace, walk along the low-CRI street and parking light lighting, and go home to CFLs, you're missing out on some healthy lighting. I feel and look better than my not-so-productive colleagues and sickly looking neighbors maybe because of my winter incan/halogen usage. The ghostly pale winter look is normal for the non-tanning northerners. 

I think mixed lighting has been looked at. I don't think that the cost is acceptable as of yet for single fixtures. KISS mentality rules! If your lighting situation is excessively annoying, drop the wattage of the primary light and add in a secondary fixture of competitive overlapping lighting and see what happens. You don't need to wait for someone else to figure it out.


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## Anders Hoveland (Sep 4, 2012)

What about just using a combination of cool white LED lights and low pressure sodium together? 
Yes, it might look a little less aesthetically appealing, with a mix of two different colors of light, but the colors would still sort of combine into a whitish color on the objects they illuminate. And it would still be much more efficient than either high pressure sodium or warm white LED's.

My guess is that whatever increased initial expense there would be would be more than offset by the energy savings over several years from the increase in efficiency. Low pressure sodium has an efficiency between 15–29%, while high pressure sodium has a lower efficiency between 12–22%. But the color quality of light from high pressure sodium is really not much of an improvement over low pressure; it is still an eery orange color. The real advantage of using a mix of LED and low pressure sodium would be good color quality, a nice white color. And very likely it would still be cheaper to use a combination of the two light sources together than all LED. As we all know, with LED the cost tends to be in direct proportion to the power output.

But again, the color rendering ability of this "white" light would probably not be very good. We are talking about just two very narrow frequency peaks, blue and yellow. Which is again why I suggested using cool white LED's (with just a little yellow phosphor) or adding a lower power red LED in there.

I have also been thinking about the possibility of adding deep red (660nm), turquoise (495nm), and purple (420nm) LED's to regular neutral white LED's to give a complete full spectrum. The turquoise and purple LED's have bad efficiencies, but it would only take a small quantity of these frequencies to fill in the gaps. Firstly, only a relatively small quantity of violet is found within the natural sunlight spectrum, and the phosphor coating on the white LED already gives off some green-indigo (turquoise) frequency light. It is just that there is a relative depression in that frequency region between the blue and green-yellow. And, as has already been mentioned, red LED's already have decent efficiencies (I am not sure about the exact efficiency for 660nm red LED's though). It would be important to use the deep red (660nm) LED's rather than the brighter orange-red (625nm) because this is more into the part of the spectrum where white phosphor LED's are deficient in. The yellow phosphor gives off mostly green, yellow, and orange frequency light; not so much red, especially into the deeper frequencies. For best color rendering, 660nm should be used.

So a full spectrum white LED is certainly possible, but of course there is not much point to it if it is not more efficient than a halogen filament. I do not have the information to actually do a calculation, but I would think that the high efficiency of the white LED, and the moderate efficiency of the red, would more than offset the small ammounts of purple and turquoise added in.




blasterman said:


> HPS would work better in a theoretical hybrid lamp because it has a broader orange-red spectrum and you wouldn't need additional color augmentation on that end.


Why not a _*cool*_ white LED (with just a little yellow phosphor) and *low pressure *sodium?
High pressure sodium is essentially just like low pressure sodium with a mercury vapor lamp mixed in.
Another advantage is that neither low pressure sodium nor LED's contain mercury. That means potentially more environmentally friendly and no UV light coming out. A small portion of people actually have skin sensitivity issues with the UV light, which would mostly affect workers working extended periods of time under flourescent or HPS lighting.



blasterman said:


> Still, all of this is a solution in search of a problem as I think we both agree. Plasma is already an option on the high wattage end of things.


Not really. LED + LPS would be extremely efficient and give off better light than either sodium or blue/cold white LED's. What's not ideal about that? I too am interested in sulfur plasma lamps, but unfortunately they are not widely available at this time and more expensive. There is also the issue of the microwaves it takes to heat the plasma. Some of this high-power microwave radiation leaks out. Is that going to be good for everyone? If sulfur lamps become widespread, we might soon find out for sure whether there is any basis for the potential health effects of electromagnetic radiation. The magnetrons currently used also tend to give off an annoying hum. And LED + LPS would still be more efficient than sulfur lamps. I think sulfur lamps, being full spectrum, have a lot of potential for indoor use, but only as long as light pipes are used to keep the actual sulfur lamps and the microwave radiation away from people.

Probably was not the best idea to bring up the subject of CFL's in this thread. I will just say that there are several reasons why I do not believe that CFL's actually save any energy over incandescent. CFL's have many issues that incandescent bulbs do not, and all these issues can potentially waste more energy indirectly. It is a very complex subject. Perhaps I will start another thread about this.




deadrx7conv said:


> I think mixed lighting has been looked at.


I have tried mixing cool white LED with halogen, and it seems to give the best artificial approximation of daylight.


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## SemiMan (Sep 4, 2012)

deadrx7conv said:


> If you quit worrying about specific spectrums and nm's, mixing bulbs can make certain lighting 'prettier' and 'more pleasing', especially if certain fixtures are already in place and working acceptably. Adding in that 'other type' of lighting can help and it doesn't even need to cover the 'entire area', or even be in the same fixture. It can also be a backup to when the main bulbs blow. You don't need to cover every possible wavelength.
> 
> I'm trying to be 100% CFL/LED and it isn't working.
> 
> ...




Not sure what you mean about the "hype" of the bulb data sheets. If they are Energy Star, then what is on the bulb package is what the product does. It has undergone LM79 testing in an accredited lab and has done limited life testing for specs and color maintenance. What you buy is what you get. No, a 750 lumen PAR38 is not going to replace a 90W, 1200+ lumen halogen, but then again, there are 1100 lumen PAR lamps on the market that pretty much do now, at least when they are new.

Efficiency of coal plant = 40% (very best). Hence electric heat is at best 40% efficient as some of your electricity comes from coal or at least is not being used to offset coal usage. 90%+ for natural gas (much cleaner too) and even 80%+ for oil. That is far less greenhouse gases for the same amount of heat. A 100w incandescent bulb takes about 20W of air conditioning to eliminate the heat so yes there are advantages to LED in the summer, but it makes the advantage 6:1 instead of 5:1.

What your body needs is blue/UV, this is what eliminates SAD and stimulates vitamin D, etc. Your halogen lights are not going to help there. Heck, they barely stimulate the sensors in your eye that control circadian rhythm. If you want to feel better, get some wide spectrum high CRI fluorescents for your office as a start instead of the 3500-4000 that is common. That will make you feel better and put less strain on your eyes.

Anders, while blue LEDs are highly efficient, your eye is terribly inefficient in this area. Adding blue increases CRI, but it hurts efficiency. 

There are 98CRI LED lighting engines available at 50+ lumens/watt that you will not be able to tell from incandescent they match the spectrum so accurately. Why would I go back?

On the LPS "kick". LPS is a huge source. That makes it difficult to control. That makes it useless for controlled outdoor lighting. It is great if you want to light up the neighborhood, but most people want to light up a specific area. This is one of the big advantages of LEDs -- optical control. And again, they are different optical sizes, they decay differently, etc. You can't mix them effectively and come up with anything "useful".

AND, don't get hung up on initial lumens/watt. Sure LPS may have a lot of lumens when it first is installed, but it can decay to 70% of its initial output in 10,000 hours. New LED outdoor fixtures are being rated 85% output to 50,000 hours. Add to that loss of 30% output in 10,000 hours is that LPS bulbs fail. At their rated life, < 20,000 hours, 1/2 of them have failed.

Okay, I am done with this thread. Like I said to the original poster, perhaps you should do some research instead of just writing off the cuff. You tried to write as "fact" without even understanding the basic concept of a lumen.


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## deadrx7conv (Sep 4, 2012)

LED hype and not bulb hype. Difference is that everyone is quoting the efficacy of the newer fancy LED's when the actual finished bulb is considerable less efficient. EnergyStar also doesn't mean much too me(as do many so called low parameter specs). EnergyStar is just a pathetic starting point which was used to dump CFL on the consumer with warm fuzzy feelings. All the pollution from the manufacturing of the LED and their driver components, along with the disposal...... we'll just dump that on Asia too. http://pubs.acs.org/doi/abs/10.1021/es101052q

Not worried about coal. I pay up for the 'green' energy in my utility bill, and wonder how many broken dysfunctional broken wind turbines would I need to heat the water or residence. Plus, the 3 larger/main power plants around here are CNG. I don't care for any anti-coal agenda either and understand that not all heating sources are common or available everywhere so efficiency arguments among fuel choices is meaningless. I even have been known to use a 1/4-1/2 ton of coal for heating which depends if I'm in the mood to chop wood all summer and shovel coal during the winter. I make sure that the coal dump truck unloads at the end of the driveway so that I offend all the eco-enviro snobtzi's. Where does our powerplant oil come from and do you know who died for it? I made my post to make sure anyone reading this can understand the options and research it for themselves so that they don't get certain tech shoved down their throat. I think that the OP made a valid argument. Bringing in the energy source didn't add anything to this thread. 

Trying to hunt down the latest fanciest higher CRI CFL for tubes, A19, or PAR30/38 fixtures is not worth the effort when I can simply toss in a incan or halogen(at least during the winter). I do have a large collection of LED and CFL bulbs for whenever the A/C season starts(and I'm usually not indoor much). Ordering your employer to purchase more expensive supplies isn't always the easiest argument to win. But, we did get permission to have low wattage cubicle table lamps(great for those that want LED, halogen or a good ol' incan option). And, it didn't take much to stand on a cubicle to disable the ugly/unhealthy/blinding work flourescent tubes. 

Where are the unlimited supply of those 98CRI 50+ lumen/watt bulbs? are they 4000-5000k? I went back for health reasons, to cut off the winter 'bathroom' heating zones, and to provide enjoyable indoor lighting during the winter months. There is more to a bulb than CRI or energy usage. After seeing seizures(neighbors kids), and noticing their lighting choices were possible a passive cause, I recommended going back and incidents were greatly reduced. Migraines anyone? Change your indoor lighting. Not feeling like getting up in the morning during the 'cold months? Change your indoor lighting. Its not all about using the least amount of energy when considering the costs of meds these days, lost days of work..... 

Concerning the LPS/HPS lighting, since it floods the front, side, and back yards reasonably well where I don't need additional lighting is ok with me. If for some reason I do need more lighting, then I turn on my outdoor LED, LVD, CFL, halogen, or.... which adds to the lighting from the city streets. Works/looks really well even if the CRI is sub standard for the total light mix. I also understand that a few towns/cities did 'alternating' light testing among LPS or HPS with LED lighting going down the street. Would've loved to see a street lit with alternating/competing techs on the utility poles. I think that LVD/sodium would be an interesting mix on a street pole and is why I brought up CFL. Most of my multi-bulb fixtures have been 'mixed' up with LVD/CFL/halogen/incan/LED more than once. 

I think that the OP understands the basic concept of the lumen as does anyone who owns a light bulb, and probably doesn't live in some ideal dream world. All the types of lights are complex subjects. Problem is that the data is usually 'skewed' for a 'cause' and manipulated too much. Once everyone understands that, they'll be able to pick what is best from there for themselves. It sure beats being a narrowmindedprick who thinks that there is only one way to do something. 

I just don't see a 250w LPS/HPS replaced with a 100-150w LPS/HPS surround by 150-100w LEDs in a common serviceable fixture because it isn't simple. I do see it as something that should be patented by a patent troll. If you have a patent lawyer, go for the single fixture 'tech' mixtures and see what happens. If Apple reads this thread, we're all doomed! The new Apple iBulb.... err.... http://www.engadget.com/2010/10/21/ge-introduces-hybrid-bulb-with-both-halogen-and-cfl-elements/ (add some LED to the hybrid bulb).


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## SemiMan (Sep 4, 2012)

deadrx7conv said:


> LED hype and not bulb hype. Difference is that everyone is quoting the efficacy of the newer fancy LED's when the actual finished bulb is considerable less efficient. EnergyStar also doesn't mean much too me(as do many so called low parameter specs). EnergyStar is just a pathetic starting point which was used to dump CFL on the consumer with warm fuzzy feelings. All the pollution from the manufacturing of the LED and their driver components, along with the disposal...... we'll just dump that on Asia too. http://pubs.acs.org/doi/abs/10.1021/es101052q
> 
> Not worried about coal. I pay up for the 'green' energy in my utility bill, and wonder how many broken dysfunctional broken wind turbines would I need to heat the water or residence. Plus, the 3 larger/main power plants around here are CNG. I don't care for any anti-coal agenda either and understand that not all heating sources are common or available everywhere so efficiency arguments among fuel choices is meaningless. I even have been known to use a 1/4-1/2 ton of coal for heating which depends if I'm in the mood to chop wood all summer and shovel coal during the winter. I make sure that the coal dump truck unloads at the end of the driveway so that I offend all the eco-enviro snobtzi's. Where does our powerplant oil come from and do you know who died for it? I made my post to make sure anyone reading this can understand the options and research it for themselves so that they don't get certain tech shoved down their throat. I think that the OP made a valid argument. Bringing in the energy source didn't add anything to this thread.
> 
> ...





Your post is somewhat of an assinnine rant, but hey I will bite.

I am pro-nuclear and yes I would prefer we end our reliance on coal because you are right, there is more to life than dollar efficiency. There is clear air, clean water ..... or any water for that matter. Have you noticed the drought? Hottest years on record in the last decade but it must be a coincidence. 99% of the scientists are probably wrong, there couldn't possibly be global warming.

"Fancy" LEDs are not much more than 100 lumens/watt at reasonable drive for 2700/3000K. Add in driver and optical losses and yes we get into the 70 lumen/watt range. 

Migraines? Seizures? ....... those arguments died 20 years ago about the same time that magnetic ballasts died off. Everyone can find cause and effect when someone wants to though......

The OP did not understand LUMEN or he would not have made the comment about LUMENS and the directionality of LEDs as a reason they were more efficient. Read the post, it clearly shows a lack of knowledge as did all the talk about efficient blue but not realizing that was radiometric efficiency (watts) not photopic efficiency (lumens).

The fact your local plants are CNG is meaningless .... though you seem to think the world ends at your small border.... Most of the North American grid is interconnected and its easy to turn off dirty energy production and instead use cleaner production from elsewhere. So great your local plant is CNG, but because you are using tons of electricity, that cannot go elsewhere to display coal usage.

Now if you are so concerned about health, why do you risk any dangers to your health by using LED/CFL in the summer? Shouldn't you just use halogen year round and live with the added electricity cost? I mean the added cost of the air conditioning is only about 20% of the energy usage of the bulb, so why even bother?

I didn't have to order my "employer" .... I provided for my employees .... and when I was an employee, I just purchased better bulbs for my work space.

So how are those fluorescents blinding? If anything those halogens with a lack of blue to properly stimulate your pupil response are what is blinding as you cannot focus properly with them. 

So Narrowmindedprick .... perhaps as opposed to living in the past and doing what you think is best for you without any regard for anyone else .... 

a) Learn .... because you have some outdated ideas
b) Actually care about your neighbors not just yourself .... and neighbor extends beyond a mile from your house.

Oh, the GE bulb? It does not mix the incandescent and the fluorescent. The incandescent is for the instant on feature and it turns off as the fluorescent warms up.


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## deadrx7conv (Sep 4, 2012)

Always match asinine with asinine comments. Don't like it, do you? I notice that you're arrogant in many threads. Couple of the mods in the auto section have the same issue. Sorry if you think that you're perfect and everything you say or do is a must and not good enough. Its definitely above your level of thinking. 
And, the directionality of LED and efficacy/efficiency is definitely relevant even if a lack of knowledge correction is needed. It didn't bother me. Get offended easily? 
I also try to balance my daily lighting needs and efficiency. And, if 20% can be saved with a simple bulb change during the summer, why not? Oh wait, I don't care for my neighbors. Its not some dictatorship where I can't use the lighting that I want when I want. BTW, in the summer, unshaded windows provide most of my lighting and but can also increase my AC cost. I balance everything as needed without being a gross energy waster(plenty of those here), or a extreme econazi unhealthy energy saving fool. 

Sorry, but your data on the CFL cure with electronic ballast is WRONG. Doesn't make a difference if magnetic or electronic as every type of lighting can affect anyone DIFFERENTLY. I even consulted with parents who can not have WIFI around there children due to allergic reactions. And, CFL lighting is also a possible trigger for other immuno responses linking to lupus/crohns/autoimmune type diseases... Every persons sensitivity and reaction to lighting, RF, sound, and EMF are different. We're not clones. You are easily brainwashed by bogus data meant to calm the masses. I've got a bridge that leads to dry land in the everglades to sell to you. 

Not everyone is in a position to rebulb several multi story buildings for several thousand employees. Bulb purchases were either low bid or sold on 'bogus data' to make the sale to the employer. As an employer, I would pay attention to employee requests. Not all employers can or do. 

A) Look in a mirror
B) Care? Thats a two way street. 

And, I know about the GE bulb. It was a decade too late and link was posted to show that mixing techs is viable for a solution. Never did find the GE one in a local store. Would be interesting for someone to reprogram it for both parts as continuous on. I would think that the L/HPS and LED combo can work great, add some redundancy as neither is perfect, but everybody wants cheap and simple. Cheap and simple is the only outdated idea that I have a problem with, but the budget must always considered. I also would think that the LED/CFL blend would work well too. But, instead we'll subsidize, outlaw, rebate, shove down your throat, whatever bulb fad that is probably not the best solution for all situations, which seems even more outdated and less neighborly. 

I wonder how well the CRT Vu1 bulb would mix with a couple LEDs. Vu1 was one order that I regret was cancelled repeatably due to inventory shortage. Forgotten but maybe I'll grab one some day.


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## jtr1962 (Sep 4, 2012)

This thread kind of reminds of a post on a computer forum where someone was upgrading their machine, but wanted to use their old video card, sound card, and some other parts in the upgrade, along with a new video card/sound card/etc. It didn't matter that everyone told them it made no sense, they probably couldn't even find a motherboard which was compatible with both types of cards, and using the old cards wouldn't gain them anything in terms of functionality or speed. They wanted to do this just for the sake of doing it.

What it comes down to is LEDs can already produce reasonably white light at a high enough efficiency on their own without needing to resort to mixing in other technologies. HPS/LPS by definition are huge sources consuming a few hundred watts and outputting tens of thousands of lumens. This by itself simply makes them inappropriate for interior lighting, whether used alone or in conjunction with other light sources. Neither technology scales well, either. A LPS/HPS lamp of a size suitable for interior lighting will only get 50 to 70 lumens per watt. You can get the same with an amber LED which has a wider spectrum. Mixing any type of incandescent with LED makes even less sense. You can just get the same wider spectrum using LED only by using a different phosphor. Your efficiency might tank to 50 or 60 lumens per watt, but that's still better than an LED/incan combo. This isn't even getting into the fact that the incan part of the LED/incan combo will need replacement every 1000 hours or so.

LED is already good enough to stand alone, and will continue to get better. Within the next year more efficient LEDs will make their way into A19 bulbs and we'll probably see overall efficiencies in excess of 100 lm/W, and with superb color rendering to boot. My experience as an engineer has told me time and again that the KISS principal makes the most sense in commercial products. It makes no sense adding complexity unless it comes with major gains in functionality. In the case of LEDs, adding other light sources gains you nothing in terms of functionality or efficiency or color rendering. Sorry but when you do the math it just doesn't. This may not immediately be apparent to a layperson but that's how it works in the real world. This is why Chevy's Volt failed. It combined the expense and complexity of being both an electric car and a gas car rather than one or the other. In fact, if you look at the dustbin of products which failed spectacularly, you'll find the vast majority of them were overengineered or overfeatured for their market. Some may have even be technical marvels, but this made them too expensive for the chosen market. Lamp replacements are by definition a mass market. Even if combining LED and other tech had some advantages, the cost of doing so would drive away most of the market who either wouldn't need these advantages, or just wouldn't be willing to pay for them. Take for example color rendering. We can already make CFLs with 95+ CRI but for most people low 80s is good enough. Either they wouldn't notice the improved color rendering, or wouldn't be willing to pay much extra for it. Here at least LEDs have a great advantage. We can get CRI in the 90s without increasing cost much. Efficiency does tank somewhat, but with LED chips getting more efficient all the time, this isn't a major issue.


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## srfreddy (Sep 4, 2012)

Wi-fi and allergic reactions.... Er... I'm gonna be on semiman's side here.


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## SemiMan (Sep 4, 2012)

Sorry if you consider well researched and knowledgeable comments as arrogant as opposed to your throw it together and hope it works comments. People who don't really know what they are doing but like to think they do are offended by those that really do.

You told me that CFL is dangerous and awful ... so why would you change them in the summer for the few hours that they are used? Pick one ... which is important to you? Are they dangerous or not. If they are, why would you use them ever? I would guess the real answer is you did not know that it only takes 1 watt of air conditioning to remove 5 watts of heat (typical of average AC these days). 

So explain to me how a CFL light would create an immunological response? Please I am really curious. There is nothing in a CFL spectrum that is not in sunlight and the level is far far less. Modern CFL does not flash either. Sure there is EMI, but no more than any number of other electronic devices in the home. Can you point to a peer reviewed scientific article that supports this?

We are not clones, but were electromagnetic energy is concerned we are very very similar. The differences are mainly chemical and RF for wifi is non-ionizing so except for long term exposure possibly causing a mutation, I can't see an immuno response. Again, do you have any peer reviewed articles?

I am sure many parents believe many things. Many parents believe that sugar and caffeine causes hyperactivity (they don't and one actually reduces it).

My comment, if you choose to read it, was that individuals in companies can make some changes to the bulbs over their work space. I know few suppliers would do this as they do not understand the advantages. 

I am not remotely brainwashed by bogus data meant to calm the masses. I actually question everything and have a pretty broad education and practical background that allows me to be a natural skeptic. Hence I don't easily believe things like wifi causing allergic responses when a) there is no good data and b) no proven (or even theorized by someone knowledgeable) good reason. 

CARE is not a two way street. It's a personal choice and that's a one way street. You do it not for rewards, but because it's the right thing to do.

This post was not about mixing technology to form "some" viable solution, but to form a specific solution. As has been discussed here, the mixing of the technologies as suggested does not.

I am sorry if some people in the Auto Forums are upset that I am almost militant in my dislike for people who put HID bulbs into halogen headlamps. It is dangerous to everyone else on the road. These illegal conversions are so easy to tell as they spray light everywhere causing dangerous glare for other people.

Democracy (not a dictatorship) does not mean being able to do whatever you want whenever you want. That is anarchy. There is a difference. In a democracy, everyone gets a say. That does not mean that your say is the majority position and sometimes you will not be able to do what you want to do.


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## blasterman (Sep 4, 2012)

> What about just using a combination of cool white LED lights and low pressure sodium together?



Rather than a low CRI at 6000k you'd have an even lower CRI at 4100-3500k, and a light source akin to a typical 65 CRI Metal Halide in the 4100k - 3500k range. As I said - good for lighting parking lots, and not much else, but I think all we differ on is exactly how ugly it would look. If that's the goal, our theoretical lamp would accomplish it. The problem is you wouldn't be adding much to visibility given 590nm isn't our best visual wavelength, and the additional lamp complexity and mixing would negate any advantage of throwing some yellow in there. Cool-white, which is already almost entirely devoid of red and amber isn't fixed by just adding amber. It will lower the CCT though, but to what advantage? 

There's no way you'd get 3000k out of it though without looking really strange.

Cree and Phillips have ANSI spec'd LED's which basically omit red or amber to increase efficiency but at the expense of good color rendering. I have some - they suck. They look white, until you view something with color under them, then you go 'bleh'. Good for our theoretical parking lot 



> I have also been thinking about the possibility of adding deep red (660nm), turquoise (495nm), and purple (420nm) LED's to regular neutral white LED's to give a complete full spectrum.



Thought about doing the same with one of my bounce lamps. I'd aim for shorter blue though, around 475 nm because 495 is very, very green. 660nm would of course help. Shorter wavelengths than 450nm are not necessary. Mixed in right and you'd have a magnificient light source that would rival a Solux. Still, the current fixtures that Cree builds have a mix of LEDs and a CRI of 90-92 and don't get any complaints. They are indistinguishable from halogen unless you have some tool to measure it. My 4100K Bridgelux emitters are around 80-85 CRI, and they destroy CFL or any fluorescent I've ever seen. Only a Solux or very high end broadcast quality HID would produce better color at that CCT.



> but of course there is not much point to it if it is not more efficient than a halogen filament


It would average no less than 60 lumens per watt if you used good LEDs. Bridgelux is up to 98CRI in warm white, and they don't have near the tech as Cree or Phillips. Show me an Ican light source more than 30 lumens per watt. Warm white LED's in the 85 CRI (or higher) range are preferred over incan in even color-critical interiour lighting.


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## blasterman (Sep 4, 2012)

Side bar, but it's rather annoying when the state of LED technology is based on what you can throw in your grocery cart at Walmart or Home Depot. LED retrofits are convenient, but the technological equivelant of 'fast food'. Some are good, some are just whatever LEDs can be thrown on a A style heat sink and marketed in a high tech box. Next aisle - cat litter and plastic plants.

Lots of us have installed or seen the better dedicated fixtures like the LR-6 or CR-6, or even their knockoffs. Of the dozen or so friends or relatives I have who've ripped out their halogen fixutures all have preferred the solid state over halogen, and the light quality is impressive. You don't even need to market the lights because somebody walks through a house with them and wants to immediately convert their own house.


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## Alaric Darconville (Sep 5, 2012)

SemiMan said:


> So how are those fluorescents blinding? If anything those halogens with a lack of blue to properly stimulate your pupil response are what is blinding as you cannot focus properly with them.


Blue light doesn't properly stimulate a pupil response. Also, halogens do not lack blue; halogen bulbs produce white light, and white light comprises the entire visible spectrum.

Excessive blue light, not the lack of blue light, is problematic, as it refracts more easily than the longer wavelengths and so focuses in front of the retina. Persons who need an extremely constricted pupil to be able to focus on things may need vision correction.


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## SemiMan (Sep 5, 2012)

Alaric Darconville said:


> Blue light doesn't properly stimulate a pupil response. Also, halogens do not lack blue; halogen bulbs produce white light, and white light comprises the entire visible spectrum.
> 
> Excessive blue light, not the lack of blue light, is problematic, as it refracts more easily than the longer wavelengths and so focuses in front of the retina. Persons who need an extremely constricted pupil to be able to focus on things may need vision correction.



Read about recent (10-15 years at max) research on new sensors found within the eye that control both pupil response and circadian rhythm. Look up melanopsin. It peaks at 470-480 nm and the drops off fairly significantly after that with nothing after 600nm. Think about where most of the lumens are for a halogen bulb and then relate them to that spectrum.

You may want to also do research on visual acuity w.r.t. lighting types and spectrum as it does show advantages for good quality cooler light.

Likely you also know about F-Stop and depth of focus?

It is not a matter of having a severely constricted pupil it is a matter of having a pupil that is properly constricted. Unless you are reading, your eye is moving around and focusing on multiple points. Even staring at a monitor you are often looking at things on your desk, etc. If you have greater depth of focus it puts less strain on your eyes and makes it easier for the eyes to be focused on any given item.

Bright halogen light is not great for fine detail work. I know you don't believe me, but get access to a high CRI daylight source of similar brightness and then try doing fine work or reading fine text. You may be surprised at the difference. Not to mention in many (not all cases) the contrast may be higher.

Extreme amount of blue lights occur in sunlight and/or when you look directly at blue sources. They are not going to occur under "normal" artificial illumination light levels.

Semiman


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## Anders Hoveland (Sep 7, 2012)

blasterman said:


> Of the dozen or so friends or relatives I have who've ripped out their halogen fixutures all have preferred the solid state over halogen, and the light quality is impressive. You don't even need to market the lights because somebody walks through a house with them and wants to immediately convert their own house.


I am actually not fully satisfied with *any *commercially available artificial light source. It seems nothing can truely match natural daylight.

Admittingly, I have never actually seen the light from a sulfur lamp, but I am not sure I would ever want one of these things in my home, with all the microwave radiation they leak out and the hum from a typical power supply. That's probably one of the reasons that light pipes are usually used with sulfur lamps, to keep the actual lamp away from where people are.

After doing much experimenting, the type of artificial light source I most prefer is halogen mixed with cool white LED light. This seems to most closely approximate sunlight.

I never had a problem with normal incandescent bulbs before, but after comparing them to alternative light sources, I have come to realise how dull and yellowish they are. I like Reveal filter bulbs, but they are not perfect either, their light seems a little greenish, and it just seems a little "off" somehow in a way I cannot describe. The warm white LED's are just okay, but the light they give off seems to be an eery yellow-pink. I like the light from cool white LED's, but it is just too blueish.

And I just hate fluorescent light, even the "full spectrum" (it's NOT full spectrum!). The actual color rendering just does not look vibrant, and the tint is still a little off, typically with either/both a slight pinkish or greenish tint. Flourescent light is a bright white color, but it is just the quality of the light. That, and I have slight skin sensitivity issues for some reason.



SemiMan said:


> There are 98CRI LED lighting engines available at 50+ lumens/watt that you will not be able to tell from incandescent they match the spectrum so accurately.


Sounds good, but as far as I know they are not really readily commercially available. They would probably be prohibitively expensive at this time if they were. And I wonder whether that slight ammount of violet light found in halogen bulbs, but probably not found in this 98CRI LED, would make any significant difference in the quality of light. And ideally I would want a little cyan frequency in there to help fill the little spectrum depression between the blue and green.



SemiMan said:


> So explain to me how a CFL light would create an immunological response? Please I am really curious. There is nothing in a CFL spectrum that is not in sunlight and the level is far far less.


I am not entirely sure. Fluorescent tubes, but especially CFL's, tend to leak UV frequencies, some more than others. I am not sure, but some of these frequencies may be of a higher intensity than found in sunlight.

I can only speak from my own biased experience, but it seems like I have much more sensitivity to CFL's than to sunlight, although I tend to get sunburn rather easily in the middle of the day if out for more than an hour. One would _think_ that my skin would be more sensitive to sunlight, but this is just not my experience. Again, I am not sure why. Another possibility is that fluorescent light could be giving out far range vissible violet light, and that my skin could be a little sensitive to this, similar to how some suffer from certain medical conditions, or side effects from certain medications.

You might read "The Truth About Lumen Ratings" by Ryan Mayrand, which explains how many LED manufacturer's lumen ratings are not realistic.


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## Anders Hoveland (Sep 7, 2012)

jtr1962 said:


> What it comes down to is LEDs can already produce reasonably white light at a high enough efficiency on their own without needing to resort to mixing in other technologies.


A typical commercially available warm white LED lamp (without any blue light) will get only 35 lumens per Watt. No doubt white LED's have achieved much higher efficiencies, but I do not think these are commercially available (and is this for the just the LED itself or including the power supply?). In any case, LPS + blue LED would still have a higher efficiency than even the best white LED's, although of course with horrible CRI.



jtr1962 said:


> A LPS/HPS lamp of a size suitable for interior lighting will only get 50 to 70 lumens per watt.


True, but this is still greater than what a typical commercially available warm white LED lamp can achieve. There is a huge gap between measured laboratory efficiencies of cutting edge LED chips, and what actual commercial LED lamps, power supply and all, have. If I am wrong, please show where I can buy industrial amber LED lighting that achieves over 50 lumens per Watt.



jtr1962 said:


> LED is already good enough to stand alone


LPS + LED would still currently be less expensive than all LED.



jtr1962 said:


> It makes no sense adding complexity unless it comes with major gains in functionality.


That is the issue here. It just seems wasteful to me to be enhancing the color of sodium lamps with mercury when blue LED's are more efficient than mercury vapor lamps. Would it really be adding so much complexity to combine two light sources? The gains in functionality would be lower cost and more efficient white light.



jtr1962 said:


> In the case of LEDs, adding other light sources gains you nothing in terms of functionality or efficiency or color rendering.


LED's are most efficient at producing blue light. Low pressure sodium is most efficient at producing yellow light. Trying to get both blue and yellow light by making modifications to either light source (such as white LED's or high pressure sodium) sacrifices efficiency for the sake of simplicity.


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## SemiMan (Sep 7, 2012)

Anders Hoveland said:


> A typical commercially available white LED lamp will get only 35 lumens per Watt. No doubt white LED's have achieved much higher efficiencies, but I do not think these are commercially available (and is this for the just the LED itself or including the power supply?). In any case, LPS + blue LED would still have a higher efficiency than even the best white LED's, although of course with horrible CRI.



Outdoor fixtures are commercially available at over 100 lumens/watt including ALL losses. There are many suppliers, and 90 lumens/watt in cool white for a street light is pretty much the norm. Cree has released indoor fixtures that are warm white and hit 110 lumens/watt for the high efficiency version shipping probably now with the 100 lumen/watt version readily available.. That includes all losses, electrical, optical, and temperature stabilized. I can buy commercial LEDS, holding them in my hand right now, that are 150+ lumens/watt, at operating temperature, at usable in a real world product drive currents. With a 92% efficient power supply, and say 15% optical losses, I am hitting 120+ lumens/watt out of the fixture in cool white. I can go into Home Depot and buy bulbs that are over 60 lumens/watt in warm white right off the shelf. Heck I can buy cheapy warm white fluorescent tube look LED lights that are 80+ lumens/watt.

Do some research!

If you add blue LED to LPS, you do not do much to improve the spectrum and you kill the efficiency. There is no valid reason to do it.

Yes it is complex to add multiple sources and as so many people have pointed out there is NO technical reason to do it. You are unlikely to end up with a light of equivalent CRI as HPS and higher efficiency than a WHITE LED. You certainly will not have higher application efficiency than a white LED, and you will have something much more expensive, complex, prone to failure, difficult to control, etc.

AGAIN, DO SOME RESEARCH!


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## SemiMan (Sep 7, 2012)

Xicato modules are readily available and while comparatively, I think there are about 30-40 companies making lights with their modules. Indistinguishable from halogen at full brightness, but of course you can get 3500 and 4000K as well in high CRI. 98+ CRI for their artist series and a full spectrum. They are only 50-60 lumens/watt as you need to make some unusable near IR to guarantee the full spectrum.


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## blasterman (Sep 7, 2012)

> AGAIN, DO SOME RESEARCH!



You said it, but I don't think he's bothering to read our replies.

The OP is either stuck in 2002, or somebody is playing a joke on us but his specs are so absurdly outdated. 

Next we'll be told that Cree has yet to breach than 50 l/watt barrier.


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## Anders Hoveland (Sep 7, 2012)

SemiMan said:


> Cree has released indoor fixtures that are warm white and hit 110 lumens/watt for the high efficiency version shipping probably now with the 100 lumen/watt version readily available.. That includes all losses, electrical, optical, and temperature stabilized. I can buy commercial LEDS, holding them in my hand right now, that are 150+ lumens/watt, at operating temperature, at usable in a real world product drive currents.


Can you give some links?



SemiMan said:


> If you add blue LED to LPS, you do not do much to improve the spectrum and you kill the efficiency. There is no valid reason to do it.


For scaled up outside lighting (such as for parking lights or security) such a hybrid warm white light source would still be more efficient than that 110 lumen per watt warm LED lamp you mentioned. And I have reason to suspect that, even given the same lumen rating, a sodium lamp would have a significantly higher light output and provide better lighting, because of wider angle illumination, or perhaps because the effective lumen rating of the sodium bulb would increase when factoring in the reflector. Without really knowing the details, lumen rating just does not really tell us exactly how functional a light source a lamp will be.



SemiMan said:


> I can go into Home Depot and buy bulbs that are over 60 lumens/watt in warm white right off the shelf. Heck I can buy cheapy warm white fluorescent tube look LED lights that are 80+ lumens/watt.


The lumen rating of these LED's is very often highly misleading since LED's are so much more directional than other light sources. It has been my experience than these lumen ratings can be significantly higher than the actual light output and ability to illuminate a room. What I mean is that, if measured by the standards of an LED bulb, an incandescent bulb will have a higher lumen equivalent when one factors in the extra angle of light that reflects/disperses back from the fixture or walls. In other words, a lumen of directional LED light is not the same thing as a lumen of incandescent light.

As you mentioned, some of the commercially available industrial LED lamps may be much more efficient than what is commonly available in stores. But I wonder if some of these claims made by manufacturers are misleading also.

You might read "The Truth About Lumen Ratings" by Ryan Mayrand, which quickly explains how many LED manufacturer's lumen ratings are not realistic.

Lumen ratings can drastically change with LED's, depending on how it is measured. How the manufacter measures their LED chip may not be the most applicable measurement for the consumer.


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## mds82 (Sep 7, 2012)

Cree.com for the indoor fixtures. They have their recessed lights that are near perfect color, fully dimable and $20 at homedepot.


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## Anders Hoveland (Sep 7, 2012)

Difficult to really know without actually having one of these lamps and comparing it. But this seems promising:

Tallahassee, Florida-based cooperatively owned grocery store New Leaf Market selected Cree’s new CS18 LED linear luminaires for a recent lighting upgrade in its 13,7000 square-foot store, resulting in significant energy savings and enhanced lighting. In switching from linear fluorescents to Cree CS18® LED linear luminaires, the cooperative not only realized 57 percent energy savings in its 13,700-square-foot store but introduced a dramatic improvement in the quality and reach of its lighting
"And the amount of additional light also has been impressive. Customers have commented on how much better things look, without even knowing why."
http://www.ledinside.com/products/2012/7/cree_led_rocery_store_lighting_20120718



SemiMan said:


> If you add blue LED to LPS, ... you kill the efficiency. There is no valid reason to do it.


You obviously did not really read my post. Sodium is cheaper, and has a much lower initial cost, than LED. And a hybrid LPS + LED would still be more efficient and have a combined whiter color light than HPS. In fact, such a hybrid would be more efficient than all LED, since low pressure sodium is so efficient, at least for industrial lighting.


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## jtr1962 (Sep 7, 2012)

Anders Hoveland said:


> For scaled up outside lighting (such as for parking lights or security) such a hybrid warm white light source would still be more efficient than that 110 lumen per watt warm LED lamp you mentioned. And I have reason to suspect that, even given the same lumen rating, a sodium lamp would have a significantly higher light output and provide better lighting, because of wider angle illumination, or perhaps because the effective lumen rating of the sodium bulb would increase when factoring in the reflector. Without really knowing the details, lumen rating just does not really tell us exactly how functional a light source a lamp will be.


Warm white for outdoor lighting is the _last_ thing in the world you want. When you factor in the perceived brightness of sodium lamps, it turns out that they're no more efficient than halogens. No, that's not a typo. High CCT light sources allow you to light an area to higher perceived brightness with fewer lumens. This isn't even getting into the fact that sodium lamps kill peripheral vision. They're the last thing you should be using to light either parking lots or streets. Sadly, we didn't know any of the facts I mentioned back in the 1970s when municipalities relamped all their street lights to HPS. It was a mistake, but now we can correct that mistake by using LED with a CCT in the range from 4500K to 6000K. This is best for both peripheral vision and perceived brightness.

You are correct that lumen rating doesn't say everything about a light source. Unfortunately, when you look at sodium lights in detail beyond their lumen ratings, they look worse than LEDs, not better.



> The lumen rating of these LED's is very often highly misleading since LED's are so much more directional than other light sources. It has been my experience than these lumen ratings can be significantly higher than the actual light output and ability to illuminate a room. What I mean is that, if measured by the standards of an LED bulb, an incandescent bulb will have a higher lumen equivalent when one factors in the extra angle of light that reflects/disperses back from the fixture or walls. In other words, a lumen of directional LED light is not the same thing as a lumen of incandescent light.


Yes, and you mention yet another benefit of LEDS-they put light where you want it, and don't waste it where you don't. A directional light source is great for both indoor and outdoor lighting. An LED on the ceiling will throw nearly 100% of its light down into the room whereas an incandescent or CFL will waste probably half. What these means in practical terms is an LED fixture may only need half the number of lumens to light a room to the same level as an incandescent if it's designed to send all of its output in a 180 degree cone.


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## blasterman (Sep 7, 2012)

> The lumen rating of these LED's is very often highly misleading



From a practical perspective the performance of individual LEDs is meaningless because it's the actual OTF (out the front) lumen specification of the entire lamp that matters. For the sake of arguement I assume we aren't talking about flashlights.

The actual out the front (OTF) lumen specifications for a significant number of the more popular LED fixtures have been tested and verified on various sites including the Dept of Energy. Most of Cree's fixtures have been verified by independant testing along with most of the commercially popular fixtures. Their exact out-put is know to a decimal point. At this point it seems from your own posts you are argueing with yourself.



> Can you give some links?



In this very forum in the thread entitled "LED Measuring" for the 150lumen specs.

With LED fixtures exceeding 80-90 lumens per watt you have a solution in search of a problem, as per what I said above. I'm not even sure how you handle the heat of such a contraption given the thermal radiated from the bulb would cause huge issues with the LEDs and require active cooling.


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## EricB (Sep 7, 2012)

jtr1962 said:


> Warm white for outdoor lighting is the _last_ thing in the world you want. When you factor in the perceived brightness of sodium lamps, it turns out that they're no more efficient than halogens. No, that's not a typo. High CCT light sources allow you to light an area to higher perceived brightness with fewer lumens. This isn't even getting into the fact that sodium lamps kill peripheral vision. They're the last thing you should be using to light either parking lots or streets. Sadly, we didn't know any of the facts I mentioned back in the 1970s when municipalities relamped all their street lights to HPS. It was a mistake, but now we can correct that mistake by using LED with a CCT in the range from 4500K to 6000K. This is best for both peripheral vision and perceived brightness.


 When the cities converted, I thought I heard that it was due to efficiency, and made it safer (hence, being added to busier streets where there might be more crime, before the more suburban blocks and smaller cities). Glare also seemed to factor into it. 
HPS uses less watts, but lights the area with less glare, and I noticed that a higher CCT light had to be much brighter to illuminate a similar area as HPS.

I always preferred the higher color temperatures, and wondered since back then if a different light source might be more efficient and somehow reduce glare. I do notice that LED's (4000-5000K?) are starting to appear in various outdoor locations. All the moldcast parking lot lamps in the new Aqueduct Casino are LED, and NYC is testing a few LED street lights.

Also, it appears the OP suggested LPS plus blue LED's, but that would actually produce pink, in fact, not that far from HPS color. White would need more green.


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## Anders Hoveland (Sep 8, 2012)

jtr1962 said:


> Warm white for outdoor lighting is the _last_ thing in the world you want. When you factor in the perceived brightness of sodium lamps, it turns out that they're no more efficient than halogens. No, that's not a typo. High CCT light sources allow you to light an area to higher perceived brightness with fewer lumens. They're the last thing you should be using to light either parking lots or streets.


The yellow 589nm frequency is fairly close to the peak 550nm sensitivity of the human eye. I am not sure what you mean to say. Could you perhaps provide a link?



jtr1962 said:


> An LED on the ceiling will throw nearly 100% of its light down into the room whereas an incandescent or CFL will waste probably half.


It depends on the lighting use. While the directionality of LED light sources tends to make them more efficient in recessed lighting, non-directional light sources are still not as wasteful as you may imagine. The recessed fixture contains a reflective coating, and I doubt that 50% of the light is wasted. Most of the light directed upwards will eventually be reflected back down into the room. For ceilling lights, LED's by themselves tend to be too directional, and so some difusing optics are usually used. Increasing the angle width of the light output decreases lumens measured directly from the light source. For non-directional light sources, much of the light sent upwards out the sides is reflected off the ceilling back down into the room. So it is not so simple.



jtr1962 said:


> What these means in practical terms is an LED fixture may only need half the number of lumens to light a room to the same level as an incandescent if it's designed to send all of its output in a 180 degree cone.


No, you have got mixed up. Lumens are a measure of intensity w_ithin a given angle,_ not light output. It is just the reverse. Directional LED fixtures typically need _*more *_lumens to light a room than an incandescent bulb.



EricB said:


> Also, it appears the OP suggested LPS plus blue LED's, but that would actually produce pink, in fact, not that far from HPS color. White would need more green.


I am not entirely sure, we would have to actually try it. Blue frequency light stimulates both the eye's blue/violet cones, and to a lesser extent the green cones, while yellow frequency light stimulates both the red and green cones. Blue and yellow light together c_an_ make white light, but it probably depends on the exact frequencies. If the result is indeed pink light, it may be possible that by adjusting the blue-yellow ratio, either a blueish-white or yellowish white could be obtained, rather than pink. To be technical here, it is not really "pink" but _magenta_.

I am sure there is some complicated color analysis that could be done to calculate what the percieved color of this mix of frequencies would be. Obviously it depends on the ratios of the different color cones that are stimulated.


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## SemiMan (Sep 8, 2012)

I am sure a moderator is going to slap me but at this point it must be said. Anders, you are an idiot. YOU REFUSE to do any research and actually learn anything. YOU SPOUT CRAP about things for which you have no knowledge because you read ONE ARTICLE ONCE. That does not make you knowledgeable and in fact it seems to have made you more ignorant than if you had read nothing.

I am not going to provide links to compensate for your laziness. I told you at least one supply that does 100 lumen+ indoors.

YOU REFUSE to actually try to read and understand the posts that have been made.

YOU STILL refuse to understand that lumens has nothing to do with directionality.

YOU HAVE no concept of a third party test or what LM79 is because if you did you would know that reputable suppliers of which there are lots, do not lie about the lumens of their fixtures as they must supply certified testing reports (and do all the time!).

YOU REFUSE TO READ AND likely have no clue what an LPS bulb looks like or you would realize it is huge (comparatively) which makes it very difficult to optically control which makes it difficult to make an effective outdoor light fixture that puts the light where you want it, not sprays it everywhere and the concept of evenness is almost pointless. Compare that to and LED. AS YOU HAVE NO OPTICAL EXPERIENCE, how do you expect to effectively match two dissimilar optical sources? YOU KEEP SAYING IT CAN BE DONE .... so how would you do it oh spouting expert? Remember for exterior light especially you have to control where the light goes AND you need to have the same amount of light from the LED and the LPS goes in the same spot. AGAIN, lumen depreciation of the LPS source is quick ... so while your LED churns away, you have to replace the LPS bulb every 10,000 hours to maintain reasonable efficiency. Ever paid for an electrician with a boom truck to change a bulb? By the time you optically mix (well), have losses from multiple reflections, refractions, etc. AND take into account the LPS lumen depreciation, I highly doubt you would have 100 lumens/watt and what you end up with would have a large source size ... it would have to be at least equivalent to the source size of the LPS light (read about etendue) .... and hence you can't make a practical light fixture with good placement accuracy and even distribution.


AND LAST BUT NOT LEAST, BEFORE EVER POSTING AGAIN, PLEASE DO SOME RESEARCH AND LEARN WHAT A LUMEN IS. YOU DO NOT KNOW AS MANY HAVE POINTED OUT!!!!!









Anders Hoveland said:


> Can you give some links?
> 
> 
> For scaled up outside lighting (such as for parking lights or security) such a hybrid warm white light source would still be more efficient than that 110 lumen per watt warm LED lamp you mentioned. And I have reason to suspect that, even given the same lumen rating, a sodium lamp would have a significantly higher light output and provide better lighting, because of wider angle illumination, or perhaps because the effective lumen rating of the sodium bulb would increase when factoring in the reflector. Without really knowing the details, lumen rating just does not really tell us exactly how functional a light source a lamp will be.
> ...


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## mvyrmnd (Sep 8, 2012)

Anders Hoveland said:


> No, you have got mixed up. Lumens are a measure of intensity within a given angle,not light output. It is just the reverse. Directional LED fixtures typically need _*more *_lumens to light a room than an incandescent bulb.



You are half right.

Yes, part of the SI value of a lumen involves angle.

From Wikipedia: "The lumen can be thought of casually as a measure of the total "amount" of visible light in some defined beam or angle, or emitted from some source."

If you have a ceiling mounted LED, aiming at the floor, then all of its lumens are aimed down, achieving a certain Lux at floor level.

In order to achieve the same Lux at floor level from a omni-directional light source (eg, incandescent bulb) then you'll need more lumens, to account for the wider angle of emission.



Anders Hoveland said:


> The lumen rating of these LED's is very often highly misleading since LED's are so much more directional than other light sources. It has been my experience than these lumen ratings can be significantly higher than the actual light output and ability to illuminate a room. What I mean is that, if measured by the standards of an LED bulb, an incandescent bulb will have a higher lumen equivalent when one factors in the extra angle of light that reflects/disperses back from the fixture or walls. In other words, a lumen of directional LED light is not the same thing as a lumen of incandescent light.
> .



A lumen is a lumen is a SI value called a lumen.

You're talking there about Lux.


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## Anders Hoveland (Sep 8, 2012)

The lumen can be thought of casually as a measure of the total "amount" of visible light in some defined beam or angle

*lumen* - the unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity.




mvyrmnd said:


> In order to achieve the same Lux at floor level from a omni-directional light source (eg, incandescent bulb) then you'll need more lumens, to account for the wider angle of emission.


except that the lumen rating from an LED source is usually at a narrow angle. 

We still do not understand eachother. Here, let me try to correct your statement:
In order to achieve the same Lux at floor level from a directional light source (eg, LED bulb) then you'll need more lumens, to account for the narrower angle of emission.

Again, much of the omni-directional light being sent out in non-ideal directions will still end up being reflected back into the room. Lighting a room requires light being sent out in all direction throughout the room, not just the floor (but obviously sending light up at the ceilling is not the best use of light either, even though much of it is difused back down again.

Given two light sources that have the *s**ame *total light output, the LED will usually have a much higher lumen rating than an incandescent. Yet the lumen rating of the incandescent will tend to increase when put in directional fixture, whereas the lumen rating for the LED will not change.

Unless we are using a 360 degree angle (which is almost never used) the lumen rating is not how much light output there will be.




SemiMan said:


> YOU STILL refuse to understand that lumens has nothing to do with directionality.
> 
> PLEASE DO SOME RESEARCH AND LEARN WHAT A LUMEN IS. YOU DO NOT KNOW AS MANY HAVE POINTED OUT!!!!!


I suspect it is you who does not really understand what a lumen is, or how it relates to directional lights.
Given two light sources with the same lumen rating, the directional light source will have a lower light output than the omni-directional one.


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## SemiMan (Sep 8, 2012)

mvyrmnd said:


> You are half right.
> 
> Yes, part of the SI value of a lumen involves angle.
> 
> ...




Actually I believe he is talking candela, not lux. Lumen is total light (photopically adjusted), lux is measure of intensity of light hitting a surface, and candela is a measure of intensity, or amount of light in a given angle. For comleteness, nit is a measure of the brightness of an emissive surface. Lumen is dimensionless and is just watts * luminosity function. All the other measurements includes some dimensional characteristic whether it be area (lux), angle (candela), or area and angle (nit).

Semiman


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## mvyrmnd (Sep 8, 2012)

SemiMan said:


> Actually I believe he is talking candela, not lux. Lumen is total light (photopically adjusted), lux is measure of intensity of light hitting a surface, and candela is a measure of intensity, or amount of light in a given angle. For comleteness, nit is a measure of the brightness of an emissive surface. Lumen is dimensionless and is just watts * luminosity function. All the other measurements includes some dimensional characteristic whether it be area (lux), angle (candela), or area and angle (nit).
> 
> Semiman



Ah. All correct  I should have read further through the Wiki page


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## Anders Hoveland (Sep 8, 2012)

I do not mean to get anyone frustrated or start an argument. I am just saying that lumen ratings cannot really be used as a measure of efficiency when comparing directional LED's to other light sources, because the lumen rating, by its definition, simply does not measure all the light given off by a light source.


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## mvyrmnd (Sep 8, 2012)

Anders Hoveland said:


> I do not mean to get anyone frustrated or start an argument. I am just saying that lumen ratings cannot really be used as a measure of efficiency when comparing directional LED's to other light sources.



And once again: lumens are lumens no matter where they come from. So they can indeed be used as a measure of efficiency.


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## IMSabbel (Sep 8, 2012)

Anders Hoveland said:


> I do not mean to get anyone frustrated or start an argument. I am just saying that lumen ratings cannot really be used as a measure of efficiency when comparing directional LED's to other light sources, because the lumen rating, by its definition, simply does not measure all the light given off by a light source.



Seeing this response after the previous posters I am >90% sure you are a troll. If not, take a close look here:

http://en.wikipedia.org/wiki/Lumen_(unit)
http://en.wikipedia.org/wiki/Candela
http://en.wikipedia.org/wiki/Lux

Lumen IS the total flux. Per definition. Look at the very first line of the Lumen article. But knowing your kind, you will pull out the "Wikipedia is always wrong" card.


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## Anders Hoveland (Sep 8, 2012)

mvyrmnd said:


> lumens are lumens no matter where they come from. So they can indeed be used as a measure of efficiency.


Yes, but they are _*within a selected angle*_.



Anders Hoveland said:


> from the lumen entry on wikipedia:
> "The lumen can be thought of casually as a measure of the total "amount" of visible light in some defined beam or angle"
> 
> *lumen* - the unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity.






IMSabbel said:


> Seeing this response after the previous posters I am >90% sure you are a troll. If not, take a close look here:
> http://en.wikipedia.org/wiki/Lumen_(unit)
> 
> Lumen IS the total flux. Per definition.


Yes, I basically agree. Lumen is the total flux within a given angle, as per the definition.

When comparing LED to other lightsources, perhaps it would be much better to refer to total flux rather than lumens when comparing efficiencies.




IMSabbel said:


> Seeing this response after the previous posters I am >90% sure you are a troll.


I just do not understand what exactly you disagree about anything I have stated.




IMSabbel said:


> Look at the very first line of the Lumen article.





> The *lumen* (symbol: *lm*) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source


That first line is not really technically accurate, and certainly is misleading here. But read the rest of the article. I am not saying Wikipedia is wrong, just that the concept of lumen is not easily worded into a single sentence without further explanation. They key word here in this line is "measure", meaning lumens are _*a measure*_ of light emitted by the source, but not really the *same* thing.

I do not really want to get into a detailed argument about whether or not a specific sentence by itself was completely true or not, or what the writer of that article was trying to convey.

Perhaps if you look up the formula for how lumens are calculated it will help clarify things.
http://www.conservationphysics.org/lightcd/lumen.php


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## SemiMan (Sep 8, 2012)

Can I repeat. ANDERS, YOU ARE AN IDIOT AND YOU KEEP ARGUING LIKE ONE.

READING A WIKI ARTICLE DOES NOT MAKE YOU AN EXPERT.

I DESIGN LIGHTS FOR A LIVING. I HAVE A LAB. DO YOU?


Lumens is not light in an angle, PERIOD. The thing you quote is called an equality statement. By DEFINITION, a Lumen is the AMOUNT of light of one candela per steradian. BUT by definition

CANDELA is WATTS/STERADIAN * Luminosity Function so when you do the math:

Watts * Steradians * luminosity function
----------
steradian

The two angles cancel out and you get watts * luminosity function! OR LUMENS!

THE ANGLE DOES NOT MATTER. HOW MANY PEOPLE WHO KNOW WHAT THEY ARE TALKING ABOUT HAVE TO SAY THAT?

You are arguing about something you do not understand. Instead of doing that, try to learn. TRY! .... or open your mouth again and prove what we already believe.


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## slebans (Sep 8, 2012)

IMSabbel said:


> Seeing this response after the previous posters I am >90% sure you are a troll.



A quick search on Google will allow you to increase the percentage from 90 to 100.


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## SemiMan (Sep 8, 2012)

Cause I know the next argument.....

- The CANDELA is called a base unit. It is a definition. Why is the Candela the base unit? It's a historical definition that appears based mainly on a few facts. One is that for the most part, optical intensity is the most important optical measurement. Two, we did not have the ability to measure optical power in the past. In the past, the optical intensity was based on a real candle that had approximately a 360 degree emission. HOWEVER, once we were able to accurately measure power, the candela was redefined to 1/683 watts at 540 * 10exp12 HZ in a solid angle of 1 steradian. 

Could they have defined a base unit as 1/683 watts at 540 * 10exp12 HZ? It would have been close, but not a lumen, but they did not.

Hence we have the interrelated measurements we have now. LUMEN DOES NOT take into account angle. That is not debatable.


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## anuragwap (Sep 8, 2012)

Deleted!


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## Anders Hoveland (Sep 8, 2012)

http://www.wisegeek.com/what-is-a-lumen.htm


> The candela (cd) was originally called the candlepower and simply referred to the amount of luminous energy emitted by a known type of candle. Later, when it was standardized, a definition was chosen that would approximate the older definition, so that existing equations could remain the same. The modern definition of the candela has to do with the radiation emitted by 1/60 of a single square centimeter of platinum when it is at its melting point.
> 
> A steradian is a standard unit of measurement used to define a solid angle. The technical definition of a steradian is _the solid angle subtended at the center of a sphere of radius r by a portion of the surface of the sphere having an area of r2​. _In this definition, subtended has to do with the relationship between the length of the arc and the resulting angle. The steradian is unitless and is represented by the abbreviation _sr_. Mathematically, using the meter as a unit of measurement, we can then define a steradian as 1(sr) = m2​ x m-1​.So, taking all of this together, we can now interpret our original definition of a lumen as 1(lm) = 1(cd) x 1(sr). One lumen in this case is a measure of the amount of luminous flux emitted into an area by 1/60 of a single square centimeter of platinum at its melting point into a certain angle.


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## SemiMan (Sep 8, 2012)

Anders Hoveland said:


> http://www.wisegeek.com/what-is-a-lumen.htm



Some people are believed to be idiots while others choose to open their mouth and remove any doubt..... or in your case type.

Keep quoting things you don't understand. It is highly valuable.

The modern definition of the candela has not been based on a heated platinum piece for oh .... 30 or 40 years.

Great post though. Just prove again how really little you know. IDIOT ... it really rolls off the tongue nicely 



What truly blows me away is you can't handle the grade 5 math, you know simple fractions, that would tell you that lumens has nothing to do with angle. Or could it be lack of language understanding that does not allow you to know understand what a definition is or derived unit?


By your logic .... a meter is defined as the distance that light travels in a given period of time. Hence if it is dark, then things cannot have any dimensions ....  ... or if I don't know the speed of light, I can't possibly measure anything. 



Oh by the way, the last line in that not so wise geek quote is actually wrong. It is the not a "certain angle" or an area ... but a steradian independent of area.


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## jtr1962 (Sep 8, 2012)

Anders Hoveland said:


> The yellow 589nm frequency is fairly close to the peak 550nm sensitivity of the human eye. I am not sure what you mean to say. Could you perhaps provide a link?


Read all about it.

The above link goes into great detail about why sodium lighting is lousy even if a lot of its output is near the peak of human visual sensitivity. The most important reason why sodium lighting stinks is due to the shift is peak visual sensitivity from 555nm yellow-green at photopic (daytime) light levels towards the blue-green region at mesotopic and scotopic light levels.



> It depends on the lighting use. While the directionality of LED light sources tends to make them more efficient in recessed lighting, non-directional light sources are still not as wasteful as you may imagine. The recessed fixture contains a reflective coating, and I doubt that 50% of the light is wasted. Most of the light directed upwards will eventually be reflected back down into the room. For ceilling lights, LED's by themselves tend to be too directional, and so some difusing optics are usually used. Increasing the angle width of the light output decreases lumens measured directly from the light source. For non-directional light sources, much of the light sent upwards out the sides is reflected off the ceilling back down into the room. So it is not so simple.


Actually, it is simple. The more lumens which go where you want them the better. An LED mounted on the ceiling _without_ optics will send 100% of its light to the room below. Assuming you have an LED and an incandescent outputting the same number of lumens, the room will look brighter with LED always. There are significant losses when 360 degree light sources bounce light off ceilings. There are also significant losses in fixtures. 50% fixture losses are about average in typical contractor-grade incandescent ceiling fixtures. Even really good T5 fixtures with mirror-finish reflectors have about 10% fixture losses. LEDs mounted on a slab of aluminum on the ceiling have 0% fixture losses.


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## Anders Hoveland (Sep 8, 2012)

But are not lumens the ammount of light within a *steriradian* from the light source, not the total ammount of light given off by the light source?




jtr1962 said:


> The most important reason why sodium lighting stinks is due to the shift is peak visual sensitivity from 555nm yellow-green at photopic (daytime) light levels towards the blue-green region at mesotopic and scotopic light levels.


It's a mixed bag of fruit:
http://www.patmullins.com/scotopic_spin.html


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## jtr1962 (Sep 8, 2012)

Anders Hoveland said:


> But are not lumens the ammount of light within a *steriradian* from the light source, not the total ammount of light given off by the light source?


You're confusing _intensity_ with total light output. Intensity is generally measured in candela. A more intense light source does indeed have more lumens per steradian. However, that doesn't tell the entire story. The output of a light source is defined as the total number of lumens emitted over the _entire sphere_, not over just one steradian. There are 4*pi or 12.56636 steradians in a sphere. Now by definition a light source with an intensity of 1 candela will emit 1 lumen per steradian. If this light source uniformly emits light over an entire sphere then it will emit 12.56636 lumens. If the light source only emits light over half the sphere it will emit 6.28318 lumens and so forth. If it emits light only over one steradian then it will emit 1 lumen. Note that in all these examples the intensity of the light source is the same even though the outputs are different.

If we think of light as water, then intensity tells us how high the water pressure is, and lumens tells of how much water is flowing. I hope this helps.


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## EricB (Sep 8, 2012)

Anders Hoveland said:


> I am not entirely sure, we would have to actually try it. Blue frequency light stimulates both the eye's blue/violet cones, and to a lesser extent the green cones, while yellow frequency light stimulates both the red and green cones. Blue and yellow light together c_an_ make white light, but it probably depends on the exact frequencies. If the result is indeed pink light, it may be possible that by adjusting the blue-yellow ratio, either a blueish-white or yellowish white could be obtained, rather than pink. To be technical here, it is not really "pink" but _magenta_.
> 
> I am sure there is some complicated color analysis that could be done to calculate what the percieved color of this mix of frequencies would be. Obviously it depends on the ratios of the different color cones that are stimulated.



I've seen the amber mixed with blue. Like the 590nm amber LED's, which are identical in output to LPS. Many signs that stores have in the windows have red and green, red and blue or amber and blue. When the amber/blue are mixed, you get a pale electric pink (not magenta, which is pure red + pure blue and much more saturated). 
With a less saturated amber; on the RGB sign that I'm using as my avatar; since the green is 565nm (it's a rare sign; most RGB's use 525), this stimulates more red cones, hence looking yellower. When you add the red to it, you get a similar amber as 590, just not as saturated, of course. When you simply add the blue to this, you get the same pink, practically; just not quite as saturated. You can see this in the middle of the picture, though the colors are distorted by the camera. The closest thing to a pure white is what the sign program calls "light aqua", which is green with blue at half intensity (no red at all; it's already in the green). 

Now, on regular RGB, with the 525 green; red + green is usually a pure sunflower yellow, and _this_ mixed with blue is an almost pure white. Think of what in subtractive mixing would be a primary "pure" yellow, yielding pure white, while the amber is more reddish, so it yields a reddish white (pink).

So to try to make a LPS white, you would have to add both blue and some green LED's, to offset the excess red (actually, the excess stimulation of red cones in the eye).

Also, there is white SON, which is a HPS that has more mercury and other stuff in it, so it's almost like an incandescent, just more on the pink side.


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## SemiMan (Sep 9, 2012)

Good post EricB, though the intended recipient will likely still argue with you .......

One fundamental "issue" with this whole thread is that High Pressure Sodium is not simply the mix of the spectrum of LPS and mercury vapor. LPS in a highly monochromatic light source. HPS on the other hand, has a fairly rich spectrum from about 550 to 700nm, with a somewhat monochromatic peak just under 500. To that end, while it does not have good color rendering, it has some.

If you were to mix monochromatic LPS with monochromatic blue, the CRI of HPS would appear awesome in comparison. Think negative CRI (yes it is possible).

I just did some simulations using 590 nm amber led and 465 blue. The best one can achieve is a whitish "pink" with a CRI of -10 and using realistic values for efficiency, perhaps 135 lumens/watt. You need a lot of blue to pull the LPS into anything reasonable. To get a CRI of even 10 of this combination will result in a blue light with a CCT >10K, and efficiency getting around 120lpw.

In either case, as has been stated many times, mixing LPS and blue LED will result in a terrible light with quality and efficiency well below the state of the art in readily purchasable white LEDS. And that is just the source efficiency. After optical tricks the results will be much much worse!


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## Anders Hoveland (Sep 9, 2012)

I just went to my local park. When I went to the bathroom, much to my surprise, I discovered that they had switched out the high pressure sodium lamps with LED's. 
They were 1-chip LED flood lights, and I think they were pure blue, either that or extremely cold white because there barely seemed to be any white to it. But I also noticed that these LED lights were very noticeably not as bright as the HPS lights they replaced (there was still an HPS lamp that had not been switched out so I could make an easy visual comparison). I wonder if the LED replacements were marketed as the "equivalent" of these other lamps, no doubt based on some scoptic index. Higher powered LED lamps tend to cost proportionately more, so I wonder if someone was trying to cut costs.

I wonder if cities would be too reluctant to switch to LED's if they had to buy the power of LED lamps that actually were actually as bright as the sodium lamps. But then again, 589nm and 465nm are two different types of light with different visual effects, so it is not so simple to directly compare them.


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## mvyrmnd (Sep 10, 2012)

Anders Hoveland said:


> )I wonder if the LED replacements were marketed as the "equivalent" of these other lamps, no doubt based on some scoptic index.



Go and ask  your argument won't be proved with speculation.


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## SemiMan (Sep 10, 2012)

Anders Hoveland said:


> I just went to my local park. When I went to the bathroom, much to my surprise, I discovered that they had switched out the high pressure sodium lamps with LED's.
> They were 1-chip LED flood lights, and I think they were pure blue, either that or extremely cold white because there barely seemed to be any white to it. But I also noticed that these LED lights were very noticeably not as bright as the HPS lights they replaced (there was still an HPS lamp that had not been switched out so I could make an easy visual comparison). I wonder if the LED replacements were marketed as the "equivalent" of these other lamps, no doubt based on some scoptic index. Higher powered LED lamps tend to cost proportionately more, so I wonder if someone was trying to cut costs.
> 
> I wonder if cities would be too reluctant to switch to LED's if they had to buy the power of LED lamps that actually were actually as bright as the sodium lamps. But then again, 589nm and 465nm are two different types of light with different visual effects, so it is not so simple to directly compare them.



Please post a picture of said light. While I believe that light may not be as bright, I do not believe for a minute it is "pure blue" or anything close to it unless you have some color blind issues and even then I can't think of what color blind issue would cause the effect you describe. Your post does not make any sense.


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## mvyrmnd (Sep 10, 2012)

SemiMan said:


> Please post a picture of said light. While I believe that light may not be as bright, I do not believe for a minute it is "pure blue" or anything close to it unless you have some color blind issues and even then I can't think of what color blind issue would cause the effect you describe. Your post does not make any sense.



In a public toilet they often use blue lights to make it harder for people to 'shoot up'. Maybe they've removed the HPS lights for other reasons than efficiency...


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## SemiMan (Sep 10, 2012)

mvyrmnd said:


> In a public toilet they often use blue lights to make it harder for people to 'shoot up'. Maybe they've removed the HPS lights for other reasons than efficiency...




You learn something new that you don't want to learn every day .. 


Since he said they replaced the HPS, I had assumed he meant outside as I am not sure I have ever seen an HPS light inside.


Let's see if a picture is forthcoming ......


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## Anders Hoveland (Sep 10, 2012)

SemiMan said:


> Please post a picture of said light.


Unfortunately, my digital camera does not render blue LED light in the same way as the human eye. I have taken pictures of cool white LED's before and they appear greenish and brighter than they actually appear to be in photographs.

Also, there is an autoadjust on my camera (which I am not sure how to turn off) and I do not think I could fit both the LED and HPS into the same field of view on the camera, so even if I did take two pictures it would not really show the relative brightness.




SemiMan said:


> I do not believe for a minute it is "pure blue" or anything close to.


It certainly is much bluer than the cool white LED's I have.
Using less phosphor means higher efficiency, and if they were replacting HPS, they probably are not very concerned about CRI. I was just surprised because this was the first time I had seen LED lighting in public that was not cool white.

There was one LED lamp right outside the bathroom, and one inside when one first walks through the door, but the lighting directly over the tiolets was flourescent.



jtr1962 said:


> Warm white for outdoor lighting is the _last_ thing in the world you want. When you factor in the perceived brightness of sodium lamps, it turns out that they're no more efficient than halogens. No, that's not a typo. High CCT light sources allow you to light an area to higher perceived brightness with fewer lumens. This isn't even getting into the fact that sodium lamps kill peripheral vision.


Likely this may may be the reason the LED lamps were not a warmer color.


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## SemiMan (Sep 10, 2012)

Anders Hoveland said:


> Unfortunately, my digital camera does not render blue LED light in the same way as the human eye. I have taken pictures of cool white LED's before and they appear greenish and brighter than they actually appear to be in photographs.
> 
> Also, there is an autoadjust on my camera (which I am not sure how to turn off) and I do not think I could fit both the LED and HPS into the same field of view on the camera, so even if I did take two pictures it would not really show the relative brightness.
> 
> ...




Anders, I have to interpret your reply, based on this and other messages you have posted as made up. I do not believe you personally have experienced this blue light in the bathroom as you discuss. I have to expect that if YOU can see the two lights at the same time (since you can compare the brightness), that you could just step back somewhat and do the same with a camera. Perfect color rendering aside, any camera image will do a reasonable job between showing the difference between pretty cool white and practically blue and HPS.

Anders, your credibility on this forum (and others) is practically 0. I am giving you the opportunity to improve on that. You are already making up excuses. As opposed to excuses, perhaps dated pictures, however bad, could be supplied.

Less phosphor does not necessarily mean high efficiency. Blue light is by its very nature has low luminous efficiency even though its radiometric efficiency is high. To that end, it makes more sense to upconvert it to a different and more luminous efficient color.


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## jtr1962 (Sep 10, 2012)

Anders Hoveland said:


> Likely this may may be the reason the LED lamps were not a warmer color.


I think you misunderstood what I was saying. Warm white light is certainly is far less effective in terms of both perceived brightness and visual acuity than cool white light, but in both cases I'm referring to _white_ light. And the optimum CCT for cool-white light for outdoors falls somewhere in the range of 4500K to 6000K for most people. Extremely cool light, or even worse, blue light, is certainly not optimum for lighting. Assuming that you're not making up this story about blue LEDs being installed in the bathroom, then perhaps the reason is to keep addicts from shooting up. Certainly, pure blue LEDs don't make for great lighting.

BTW, an alternate explanation here for the pure blue LEDs might be that the fixture was originally remote phosphor, but the phosphor panels were vandalized. That would make more sense as I've never heard of pure blue being used for general illumination purposes.


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## EricB (Sep 11, 2012)

SemiMan said:


> If you were to mix monochromatic LPS with monochromatic blue, the CRI of HPS would appear awesome in comparison. Think negative CRI (yes it is possible).
> 
> I just did some simulations using 590 nm amber led and 465 blue. The best one can achieve is a whitish "pink" with a CRI of -10 and using realistic values for efficiency, perhaps 135 lumens/watt. You need a lot of blue to pull the LPS into anything reasonable. To get a CRI of even 10 of this combination will result in a blue light with a CCT >10K, and efficiency getting around 120lpw.
> 
> In either case, as has been stated many times, mixing LPS and blue LED will result in a terrible light with quality and efficiency well below the state of the art in readily purchasable white LEDS. And that is just the source efficiency. After optical tricks the results will be much much worse!


I was going to give another example using actual LPS, but figured the ones I gave pretty much gave the idea.

In the subways, 20 years ago, they began replacing incandescent tunnel lights with mercury, and in this same project, emergency exits got HPS over the doorway, and alarm locations had a blue filter cup over the mercury to replace the blue incandescent bulbs. A few years later they switched to CFL, and usually replaced the exit also, and the blue with cyan CFL. Now, they're switching to LED bulbs, both white and blue. In a few places, they still have the LPS exit lights, and when you see them close together (maybe even squint, to mix the "streaks" of light on the eye), it was that same pink. Also, if they happened to leave the blue filter glass, and place the cyan CFL in the fixture, you get a deep blue that looks like 430nm LED. (It's REAL saturated! I often wonder if this is the "primary" blue of the eye cones this site: http://casa.colorado.edu/~ajsh/colour/primary.html mentions). Again, when near the HPS, same pink. (I had been "mixing" the colors like that for years, because I wanted to know what the two colors mixed look like, to get an idea of what the "white" of an RGB with 565 green looked like, long before I was able to see or get one of these signs).
Of course, now, the signals are LED as well, and when you see the amber (yellow) near one of those blue alarm lights...



jtr1962 said:


> BTW, an alternate explanation here for the pure blue LEDs might be that the fixture was originally remote phosphor, but the phosphor panels were vandalized. That would make more sense as I've never heard of pure blue being used for general illumination purposes.


 Remote phosphor would be having the phosphor on the lens or cover instead of in the LED, right?
Never knew they had that, but that would seem to make the most sense of what he was seeing. Blue LED is only good for indicators (like the alarm location lights I mentioned) or display, and I've never seen it used anywhere for illumination, unless it was some decorative thing.


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## AnAppleSnail (Sep 11, 2012)

EricB said:


> Never knew they had that, but that would seem to make the most sense of what he was seeing. Blue LED is only good for indicators (like the alarm location lights I mentioned) or display, and I've never seen it used anywhere for illumination, unless it was some decorative thing.



The more you know...


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## Anders Hoveland (Sep 27, 2012)

There seems to be a big disconnection between what a certain type of bulb's lumen rating is and how much light it actually gives off.
It is not just me who has noticed this:


ginchinchili said:


> I'm not a lighting technician, but I was told by the folks at Vu1 that measuring ESL's "brightness" in lumens is as insufficient as measuring LEDs in watts. The new bulbs are rated at 500 lumens. That doesn't sound very bright, but the bulbs that I own were actually brighter than a 65 watt incandescent. But the ESL was clearly as bright as a 65 watt incandescent. I realize there are different ways of defining "brightness", which is why I stated that I'm not a lighting technician. This same discrepancy may help to explain how an LED bulb rated at 800 lumens is only as bright as a 40 watt incandescent.


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## AnAppleSnail (Sep 27, 2012)

Anders Hoveland said:


> There seems to be a big disconnection between what a certain type of bulb's lumen rating is and how much light it actually gives off.
> It is not just me who has noticed this:



As mentioned in that review, something that puts these bulbs "head and shoulders" above the incandescent lights is the fact that they poke out a bit from the cans, eliminating that source of loss. I see a lot of par-something lights with recessed non-reflectored halogens mounted and giving diffused light by wall-bounce. This cuts the light output to about half of what it could be with better design and use of light. With such low output, you can't help but need a dozen mounted in the kitchen of any new ticky-tacky house.


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## SemiMan (Sep 27, 2012)

Anders Hoveland said:


> There seems to be a big disconnection between what a certain type of bulb's lumen rating is and how much light it actually gives off.
> It is not just me who has noticed this:



Give it a rest Anders .... you have been told numerous times that your "interpretation" of lumens is WRONG ... AND THERE IS NO DISCONNECT!

That article is simple a company trying to make something not as good to sound better. If they compare their bulb to an A19 style in can, yes they may seem brighter. However, if they compare to a PAR or R incandescent that has more lumens then they are NOT going to seem brighter unless they are at a cooler color temp which gives the impression of cooler.

STOP trying to put forward your erroneous ideas. That may work when you are talking to people have no clue, but you are in a forum with people who for the most part know far more about this than you do.

Semiman


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## idleprocess (Sep 27, 2012)

Wow. This thread certainly is ... interesting ... _in the fortune cookie sense_.

What the OP is looking for isn't going to be manufactured by industry due to cost/complexity and overwhelming lack of demand. It could be homebrewed ... but it's going to take a lot of tinkering, will be fairly expensive, and also likely quite large - good thing the OP is interested in light pipes since it's going to demand electrically/mechanically/optically/thermally disparate sources. I also suspect that it will take numerous attempts to perfect.

Secondly, this deliberately obtuse misunderstanding of the term "lumen" has just got to go. You've not only been outvoted by longstanding respected members with industry experience, but by the industry itself - which would be jumping all over the issue were it true. Give it a rest.


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## idleprocess (Sep 27, 2012)

I should probably stop responding, but what the heck...



Anders Hoveland said:


> There seems to be a big disconnection between what a certain type of bulb's lumen rating is and how much light it actually gives off.
> It is not just me who has noticed this:



Oh, some other guy also noticed and addressed that question. The individual you're quoting registered _just to post that_ and was never heard from again.

But I suspect you'll keep insisting on your very wrong interpretation. If you do, I suspect that Ignore lists will increase by one and your monologues will go unread.


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