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LED Evolution Could Spell The End For Bulbs
An anonymous reader writes "USA Today is running a story discussing how LED lamps were unthinkable until the technology cleared a major hurdle just a dozen years ago. Since then, LEDs have evolved quickly and are being adapted for many uses, including pool illumination and reading lights, as evidenced at the Lightfair trade show here this week. More widespread use could lead to big energy savings and a minor revolution in the way we think about lighting."
I know that this is true because I read it in the Bible. They did not evolve, they were created by God.
I guess we are going to start having "illumiphiles" who will try to tell us that the incandescent lightbulbs of yesteryear are somehow "warmer" and that humans can tell the difference between LEDs and vacuum tubes.
the lightbulb industry lobbies the congress to ban LED technology that will ruin the market for lightbulbs.
Dvorak on Doomtech
I think one of the main issues with LED lights is the incompatibility with existing lamps.
Sure you buy new lamps every once in a while, but a real breakthrough will come when you can get LED 'bulbs' that fit in a normal 220/110V socket on a normal lamp.
The same thing happened with those energy-saving bulbs, it seems they only really took off (at least here in Denmark where electricity is expensive) when they became available in versions that looked like normal bulbs and fit most lamps.
Another example is the wire spot halogen lights, once they became available in 220/110V versions they took off. Nobody seemed to want those bulky 220->12V transformers around.
Unfortunately, like the article says, the first cost is still prohibitive in a lot of cases, although the savings in energy would seem to make it worthwhile. LEDs also tend to get very, very hot in large quantities if they're used for a long period of time, so air circulation is a common problem as well.
Hopefully some of you computer engineers and programers can come up with a cheap way to produce and control LED arrays so I can start using them in practice! Building owners would be extremely happy if power consumption in buildings would go down significantly and if they had the ability to control the color and brightness (they are easily and cheaply dimmable, unlike flourescents) of any room individually.
This article contains material on evolution. Evolution is a theory, not a fact, regarding the origin of living things (and light sources). This material should be approached with an open mind, studied carefully, and critically considered.
"but forget mounting anything like a mag-lite on a weapon"
YOU SEE!!! Doom 3 had it right all along!
So which way am I better off? Just using lower wattage "classic" lightbulbs, or with dozens of 120V AC->5V DC converters wasting energy everywhere.
The adapter for my iBook puts out more heat then the iBook. More of the heat from my AMD64 is from the power supply vs. the CPU and Gfx.
Almost nothing I own needs over 12V anymore. When will I be able to just have one nice 120->12V spaceheater and run everything else in the room off 12V?
- Adam L. Beberg - The Cosm Project - http://www.mithral.com/
They haven't been used as sources of illumination because they, for a long time, could not produce white light -- only red, green and yellow. Nichia Chemical of Japan changed that in 1993 when it started producing blue LEDs, which combined with red and green produce white light, opening up a whole new field for the technology.
This is certainly one way to produce a white LED but it is not the common method today. Most white LEDs use a phosphor to convert a blue or ultraviolet LED into a white one. A quick google found the following page that talks about this in more detail:
http://www.marktechopto.com/engineering/white.cfm
I would speculate that for normal home lighting using a phosphor will give better results as:
Just this week, researchers at the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y., said they had boosted the light output per watt of a white LED to almost six times that of an incandescent light bulb, beating even a compact fluorescent bulb in efficiency.
The absolute best use for new-generation LEDs I have seen is for brake lights. Many high-end cars, and even some delivery trucks, use LEDs now, and the advantages are clear: they are damned bright, highly directional, don't burn out, and best of all, they reach full brightness a tenth of a second faster than an incandescent bulb. That may not sound like much, but at 60MPH, 0.1 second is 8.8 feet extra feet for the car behind you to start reacting (100km/h ==> 2.8m in 0.1s). I have blinky LEDs on my motorcycle and they solve all sorts of problems with tailgaters.
This is not my sandwich.
Warm and cool are really terms used to describe white light. When you talk about white the question becomes what is it? A blend of all the colours is an elementary explination, but the fact is they aren't all present in equal levels, from any source.
The way that it is talked about, is called colour temperature, and it is spoken of in kelvins. The idea is if you heat a black body radiator to that temperature, that's the kind of white you get. The lower the temperature, the more red in it, the higher the temperature, the more blue.
On most monitors that aren't connected via DVI, you can see colour temperature changes for yourself. In its configuration there should be a colour temperature option, generally with three presets: 5000k, 6500k and 9300k. PLay with them and notice the change. You'll probably find that changing from the one you are used to looks "wrong", either too red or too blue depending on. That's an illusion, however. If you go away for awhile and come back, or just ignore it and keep working, you'll find your eyes adjust and consider that to be white.
With bulbs, it gets more complex because it's not just a function of the temperature of the white, but of it's spectral composition. Most incandesant bulbs have a spectrum that is low on the high frequencies (near violet) and high on the low frequencies (near red). Other lights, like many floursecants, have an uneven spectrum, with peaks all over.
Now ideally what you are shooting for usually is light as close to sunlight as you can get. That's what humans would generally think of as "normal" or "correct" lighting. Easier said than done, of course.
So I don't know what the spectrum for any of the varities of white LEDs looks like, but it is very possible, even likely, that they are different than an incandescant bulb. It may be that they have a generally higher temperature and thus really are cooler, colourwise.
Mostly true. When viewed directly, the eye perceives any color in the color space defined by the three LED colors. But the actual light is still trichromatic, so it won't light up the objects in the room the way you expect them to. A beautiful yellow light might make an object of that same beautiful yellow look like a dingy brown, becuse there's no actual light of that color to reflect off the object.
Try it yourself: Tonight, set your screen background to various colors, turn off the other lights in the room, and see what things look like when lit only by the monitor. The effect isn't as pronounced, but it's still observable.
I have an interestiung anecdotal from ye olden days. Way back when, I had a girlfriend who was an artist, and going to an art school. They had a black tie affair for the students faculty and parents,so we went. Hey, free food and champers! Me in a tux, too funny! Anyway, one of the students mom's there lost a diamond out of a setting, fell on the floor someplace. So here's a couple dozen people in gowns and tuxes all bent over squinting at the floor. We saw it, went over to ask "what's up"? Got told about the loose stone, girlfriend glanced down, immediately spotted it, went over and picked it up, like one second. She saw it from her extraordinary ability to see colors. She had been tested in the school and won, ran 10,000 colors in ROYGBIV sequence not missing a single shade, the only student to get all of them correct.
What other lights?