What do you guys make of this? "LED Lighting - Fact or Fiction" ...

cmeisenzahl

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I get only get here once in a while and don't know too much about the subject. But I found this and thought some of you might be interested.

LED Lighting - Fact or Fiction
http://patmullins.com/ledlightmyths.html

"Setting the Stage
Light Emitting Diodes are just now (in 2005) claiming to double the lumens-per-watt of typical incandescent bulbs. HID (High Intensity Discharge) lamps are still 4 or 5 times higher, and LEDs may never reach that efficacy. LEDs caused the lighting industry to think in new terms, like "wall plug efficiency" and LED marketing has become more clever. Here we discuss a few hopeful ideas or rumors, and some of the reality to support or dispel them."
 

yellow

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and LEDs may never reach that efficacy
any statement like this in a field just beginning to explode,
seems like the ones of the computer manager quite some time ago :)

(like: "we see a market of 4-5 of these computers worldwide".
That was when You needed a whole building for these parts)
 

cmeisenzahl

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yellow said:
any statement like this in a field just beginning to explode,
seems like the ones of the computer manager quite some time ago :)
(like: "we see a market of 4-5 of these computers worldwide".
That was when You needed a whole building for these parts)

Yellow, good analogy, that was my gut feeling as well.
 

VidPro

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well there is a myth from the mythbuster.
saved money with LED red yellow green street signal lights
mabey they would have if sombody had done it correctally, but in this city after forking over the buku bucks that it costs to switch them over, they have been crapping out sections of the modules. WAY before the age of the led would be an issue.
same thing goes for some huge jumbotron type displays, there are lots of missing pixels on them, that before might have been a full time job replacing little incans, but because sombody didnt solder or vibration protect, or use quality components, they also are right back where they started.
at vastly higher costs for the install, and the hopes and dreams of the people who paid for an put this stuff in, they still got those dreams bashed by some unexpected problems and poor craftsmanship.

another one is signs on schools, another goverment hole for leds. what once was a florescent light sign with black lettering, has now become a computerized piece of junk that cost a load, and fails miserably. one person out of a job (changing the letters on the board) 3 people put to work, one running a computer, one fixing the board, and one wondering why it isnt working again :)

and they COULD have socketed this stuff, IF sombody had notified people of all the possibilities, instead its back to the shop with a lot of it.

He does make a great point on directionality, and awareness. these stupid chandelabras here, waste 1/2 thier light lighting a ceiling that is so high, little of the light makes it back. save 50% power with leds, then dont light what you dont use ALSO, and it beats them little florescent bulbs.

and people havent put SHADES over leds for cute design features, blowing 2/3rd of the light out.
when people go solar, they (suddenly out of the blue for some strange reason :) become aware of the actual consumption of things.
led and or solar, or even analizing anything about your consumptions, and directionality and waste, and time on, can save lots of power, most homes i have seen can save about 40% with no loss to the human. now go clean your refridgerator coils :)

Then the life time of the phosphors Vrses the LED die, is still a spec that has not been updated on much of any sales for led light.
the led WILL last for 100k hours or even more, we can prove that, because they have been burning for that long, but everything with phosphors, dies much sooner, including the CRT monitor. very few spec sheets and sales trash identifies the actual lifetime of the phosphors.

and Lumping, lumping all of leds in the same pile, when there indeed are MUCH better quality , lifetime and output ones than others.
 
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ledled

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So While LED will turn into UV when it gets old??
I thought white LED are blue LEDs in nature.


"Phosphor in most white LEDs can degrade faster than the LED junction itself. This can be caused from thermal overload or from excessive ultra-violet exposure"
 

Inferno

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I think he meant "beau-coup"?-- another way of saying big bucks. Pronounced boo-koo/buku though...
 

PhotonWrangler

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I prefer kilobucks or megabucks. Not that there's anything wrong with the French version. :p I'm really annoyed by his use of the term "efficacy" instead of "efficiency."
 

NewBie

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cmeisenzahl said:
I get only get here once in a while and don't know too much about the subject. But I found this and thought some of you might be interested.

LED Lighting - Fact or Fiction
http://patmullins.com/ledlightmyths.html

"Setting the Stage
Light Emitting Diodes are just now (in 2005) claiming to double the lumens-per-watt of typical incandescent bulbs. HID (High Intensity Discharge) lamps are still 4 or 5 times higher, and LEDs may never reach that efficacy. LEDs caused the lighting industry to think in new terms, like "wall plug efficiency" and LED marketing has become more clever. Here we discuss a few hopeful ideas or rumors, and some of the reality to support or dispel them."


His knowledge seems to be dated to about six years ago....

Thats an eternity these days.
 

jashhash

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I agree with this article. LED's still require some development before they become a standard for in home lighting.
 

VidPro

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ledled said:
So While LED will turn into UV when it gets old??
I thought white LED are blue LEDs in nature.


"Phosphor in most white LEDs can degrade faster than the LED junction itself. This can be caused from thermal overload or from excessive ultra-violet exposure"

the original gate is blue, then yelowish phosphors are being struck with the blue light.


from here, where there is a whole class credit on light of information.

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A fluorescent lamp consists of a gas-filled glass tube with an electrode at each end. This lamp emits light when a current of electrons passes through it from one electrode to the other and excites mercury atoms in the tube's vapor. The electrons are able to leave the electrodes because those electrodes are heated to high temperatures and an electric field, powered by the electric company, propels them through the tube. However, the light that the mercury atoms emit is actually in the ultraviolet, where it can't be seen. To convert this ultraviolet light to visible light, the inside surface of the glass tube is coated with a fluorescent powder. When this fluorescent powder is exposed to ultraviolet light, it absorbs the light energy and reemits some of it as visible light, a process called "fluorescence." The missing light energy is converted to thermal energy, making the tube slightly hot. By carefully selecting the fluorescent powders (called "phosphors"), the manufacturer of the light can tailor the light's coloration.

What is the composition of the phosphors used in fluorescent light bulbs?

The exact composition depends on the color type of the bulb, with the most common color types being cool white, warm white, deluxe cool white, and deluxe warm white. In each case, the phosphors are a mixture of crystals that may include: calcium halophosphate, calcium silicate, strontium magnesium phosphate, calcium strontium phosphate, and magnesium fluorogermanate. These crystals contain impurities that allow them to fluoresce visible light. These impurities include: antimony, manganese, tin, and lead
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How do light emitting diodes work and what is responsible for their different colors?

Light emitting diodes are diodes that have been specially designed to emit light rather than heat during their operations. Whenever current is flowing through a diode, electrons are moving from the n-type semiconductor on one side of the diode's p-n junction to the p-type semiconductor on the other side of the junction. Once an electron (which is negatively charged) arrives in the p-type semiconductor, it's attracted toward an electron hole (which is positively charged) and the two move together. The electron soon fills the hole and it releases a small amount of energy when it does. In a normal diode, electrons lose energy at a rate of 0.6 joules of energy per coulomb of charge as they recombine with the electron holes. That means that the current flowing through the normal diode loses 0.6 volts as it flows through the diode. The missing energy becomes thermal energy or heat. But in a light emitting diode (an LED), each electron that arrives in the p-type semiconductor after crossing the p-n junction recombines with an electron hole in a remarkable way. It gives up its extra energy as light! Each time an electron and an electron hole recombine, they emit one particle of light, a photon, and the frequency, wavelength, and color of that light depends on the amount of energy given up by the electron as it falls into the electron hole. The semiconductor material from which an LED is made has a characteristic called its band gap. This band gap measures the energy needed to pull an electron away from an electron hole in the material. If this band gap is small, the LED will emit infrared light. If this band gap is larger, the LED will emit red, orange, yellow, green, or even blue light (the farther to the right in that list, the more energy is required). Because each electron loses more energy in recombining with an electron hole in an LED than it would in a normal diode, the current flowing through an LED loses more voltage (typically 2 volts for red LEDs and as much as 4 volts for blue LEDs) than does the current flowing through a regular diode (typically 0.6 volts). Physicists, chemists, materials scientists, and engineers have been working for years to perfect the materials used in LEDs, making them more and more efficient at turning the electrons' energies into light.

Until recently, there were no suitable materials from which to build blue LEDs, but recent developments of large band gap semiconductors have made blue LEDs possible. In fact, even blue laser diodes are now being made. A laser diode is a specially designed LED in which all of the photons are copies of one another rather than being emitted independently by the individual electrons as they drop into their respective electron holes. One final note: it's now possible to obtain a "white" LED! This device is actually a blue LED, combined with a fluorescent phosphor that converts the blue light into white light.
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spokes

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.................... :p I'm really annoyed by his use of the term "efficacy" instead of "efficiency."[/QUOTE said:
The two words do not mean exactly the same thing and are not completely interchangeable. www.dictionary.com shows deffinitions for the words that seem to say that "efficacy" refers to being suitable for a given purpose and how well it works with respect to final outcome. "Efficiency" requires some sort of metric measuring an input to output ratio. When I see the word efficacy used I usually presume the person has a medical background, as one of the most common usages is in reference to a medication's efficacy for treating a specific pathology. (OK, that's all for my Cliff Claven impersonation):sleepy:
 

AJ_Dual

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The article, at least to me, is not "bashing LED's", it's just saying that when examining the effciency of a system, all inputs and outputs need to be considered. i.e. "Do the math!".

If you're replacing an incan system with LED's, and you're saving 50% on power, but paying 200% more in replacment and upkeep, it may not have been a wise decision. If you engage in capital expenditures to upgrade the lighting in an area, when repositioning shades or reflectors could have improved the efficiency of the existing system essentialy for free, that wasn't smart either.

Basicaly, the author is warning people to not let exciting new technology make single facet efficiency or cost decisions.

There's nothing wrong with that.
 

PhotonWrangler

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spokes said:
When I see the word efficacy used I usually presume the person has a medical background, as one of the most common usages is in reference to a medication's efficacy for treating a specific pathology. (OK, that's all for my Cliff Claven impersonation):sleepy:

Exactly. Efficacy implies suitability for a given purpose, while the article uses the term to disciss lumens/watt, which is efficiency.

[/nitpicking]
 

hotbeam

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That is an old article for sure!

philips57lmperwatt.jpg


You can get a Luxeon or XLamp that has those figures.
 
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