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Making Strides Toward Low-Cost LED Lighting
Roland Piquepaille writes "You all know that incandescent bulbs are pretty inefficient, converting only 10% of electricity into light — and 90% into heat. Light-emitting diodes, or LEDs, could soon replace incandescent and compact fluorescent bulbs in our homes. They are more efficient and environmentally friendly. But LED lights are currently too expensive because they are using a sapphire-based technology. Now, Purdue University researchers have found a way to build low-cost and bright LEDs for home lighting. According to the researchers, the LED lights now on the market cost about $100 while LED lights based on their new technology could be commercially available within a couple of years for a cost of about $5. It would also help to cut our electricity bill by about 10%."
Take a hint from the car manufacturers. Today, high-end cars are using LED tail lights. They are also used on trucks. The main advantage is they do not burn out.
However, for most people in the world a burned-out tail light bulb is a minor safety issue and a minor expense. Replacing the bulb takes 10 minutes and maybe the owner's manual if you are truely clueless about how to do it. Also, many people own a car for 5+ years without ever having to replace a single bulb.
Compare this to the cost of a minor traffic accident where a tail light is cracked. No, you cannot replace the lens or any individual part, just the whole assembly. Instead of $100-$200 for an incandescent bulb assembly expect to pay $1500-$2000 for the LED tail light.
Sure, over the life of many vehicles it is a minor issue that bulbs will never burn out. But over the same number of vehicles it is far, far more likely that a lamp assembly will have to be replaced. The result is a far more expensive part to replace.
With trucks there is a certain amount of sense to be made with claiming that the bulbs do not have to be replaced. Replacing a bulb on a truck or semi-trailer can be a real hassle requiring a ladder and tools. However, again the likelyhood the bulb would ever need to be replaced vs. the lens being damaged is about the same as for cars. Basically, it is a complete rip-off.
Expect to see wired-in LED systems in household lamps where the fixture must be replaced because the bulbs cannot be. Expect to see the fixtures sold to builders with non-replacable bulbs will cost the builder only slightly more when bought in huge quantities but the homeowner will be faced with $1000 lamp fixtures should they ever need or desire to replace them.
Many of these white LEDs are blue or UV LEDs that stimulate a phosphor coating to produce white light.
Having three Red Green Blue LEDs to create white light might produce a light that appears white to the eye, but might not have the same effect when reflected off material.
The white from the phosphor would generate more of a broad spectrum white, whereas the Red, Green and Blue LEDs would probably create spikes in the Red, Green and Blue spectrum.
So you might have a green material that appears black when you use the "RGB white" LED - just because it does not reflect the Green LED's narrow green, whereas it will appear green in the white from the phosphor white LED.
The phosphor means one more step in light conversion, and that probably means less efficiency.
So, suck it up, I hear you say. Right, except that each blink leaves an annoying remanent patch on my retina that lasts for a few seconds. Imagine driving at night in a city, 10 cars in your field of vision, look left, right and suddenly you have 200 spots in your field of vision. Awesome to know what's going on, right ?
I loathed the xenon high beams when they first came out a few years ago. You know, those tiny very concentrated blue lights ? Leaves a retina trail that lasts for 20 seconds. I'm so glad that they are gone now. I've never heard if they were made illegal or if they just went out of fashion, but I hope LEDs (which are a good technology) are applied in a good way...
Non-Linux Penguins ?
Another article http://pubs.acs.org/isubscribe/journals/cen/86/i28/html/8628cover4.html provides some interesting information on organic LEDs - OLEDs have interesting design applications since you can make them in flat sheets
(I think an illuminating wall would be way cool, but maybe thats just me :-))
Right now efficiencies are similar to the inorganic LEDs and fluorescent bulbs.
2003 called, it wants it's CFL stereotypes back.
CFLs don't flicker like old ballast-type fluorescent tubes of decades ago. And the newer ultra-compact ones are actually smaller than the incandescent bulbs they replace. I have one in the swing-arm desk lamp in front of me right now, and the tip of the bulb no longer protrudes past the end of the shade like the old bulbs I used in it long ago. In my bathroom I have CFL bulbs made to look identical to G25 globe lights, in the same fixture with the actual incandescent bulb I am slowly replacing. They appear the same except the CFLs are brighter and their light isn't as yellow.
I will give you the mercury, though.
not just an illuminating wall. Imagine the entire ceiling covered in an OLED sheet and have lighting do cool stuff like follow you around or whatever. Rooms with people get lit while others don't. Crazy flashy lights for parties. the possibilities are limitless!
Balderdash!
Uh...the linked article is on a purdue.edu page and has zero adds. Am I missing something?
you need to look at the Color Temperature when you buy CFL bulbs. A CFL rated at 2700 degrees Color Temperature will look almost exactly like an incandescent light. A CT of 3000 degrees is called a warm white and is very pleasing. A CT of 4000 is called a cool white and looks a little bit blue. And a CT of 5000 degrees or more is about the same color as Sunlight and appears to be very blue indoors.
I really like the color you get when a 2700 & 5000 degree light are in the same fixture, everything looks bright and colorful.
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