LED Lighting As Cheap As CFLs Invented

mcgrew writes "New Scientist reports that a British team has overcome the obstacles to cheap LED lighting, and that LED lamps as cheap as CFLs will be on the market in five years. Quoting: 'Gallium nitride cannot be grown on silicon like other solid-state electronic components because it shrinks at twice the rate of silicon as it cools. Crystals of GaN must be grown at 1000C, so by the time a new LED made on silicon has cooled, it has already cracked, rendering the devices unusable. One solution is to grow the LEDs on sapphire, which shrinks and cools at much the same rate as GaN. But the expense is too great to be commercially competitive. Now Colin Humphreys's team at the University of Cambridge has discovered a simple solution to the shrinkage problem. They included layers of aluminium gallium nitride in their LED design... These LEDs can be grown on silicon as so many other electronics components are. ... A 15-centimetre silicon wafer costs just $15 and can accommodate 150,000 LEDs making the cost per unit tiny.'"

Comments

Finally!

[1729]

Now Colin Humphreys's team at the University of Cambridge has discovered a simple solution to the shrinkage problem.

Excellent news! Wait, what's this story about?

Re:Clap on?

[ivan256]

They won't work with the clapper.

Cheap automated switching devices like the clapper and some timers include the bulb as a resistance element in the switching circuit. They count on the bulb acting almost like a short when the light is off. This works with incandescent bulbs, since the resistance of the filament is very low when it is cold. CFL and LED bulbs act exactly the opposite way. They are almost an open circuit when off. With no current flow, the automated switch is unpowered.

There are switches that will work with these types of bulbs, but they generally cost more.

Oblig seinfeld reference

[philspear]

Lightbulbs getting out of a pool I guess.

What about the production?

[Erioll]

I'm all for getting away from CFLs, as their production alone is NOT environmentally friendly (most of the mercury in the world is mined in China, where HALF of it is "lost" to the environment during production, which means "polluted"), not to mention the ratio thrown out.

But what about the LEDs? How toxic (or not) are the materials they're talking about? And what about the production of such? And heck, back on the pollution thing, WHERE they are produced makes a big difference, since if it's in China, forget any environmental disposal of chemicals used, whereas if it's in a developed country, it'll probably be OK.

Not insurmountable problems, but I do want to know how those things will work out.

Re:What about the production?

[lagfest]

All in all, a win all around, although - as someone has mentioned here - LEDs are not that 'bright' compared to traditional lighting.

I take it you've never seen a high power LED. All I can say is: don't look into high power LEDs with remaining eye.

Re:What about the production?

[danep]

Please stop spreading the FUD about the amount of mercury in CFLs, which is negligible. The mercury in CFLs constitutes 0.1% of what we dump into the environment annually, and CFLs contribute far less mercury to the environment than incandescent bulbs. http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf

Re:What about the production?

[lawpoop]

The problem with CFLs is not the mercury spread into the environment during production, is the spot concentrations of mercury 1. in your home, when you break a bulb, and 2. in the landfill, when people toss them out like regular bulbs, not understanding that these are hazardous waste and need to be disposed of in the proper facilities.

When you break a lamp, the state of Maine says "The next time you replace a lamp, consider putting a drop cloth on the floor so that any accidental breakage can be easily cleaned up. If consumers remain concerned regarding safety, they may consider not utilizing fluorescent lamps in situations where they could easily be broken. Consumers may also consider avoiding CFL usage in bedrooms or carpeted areas frequented by infants, small children, or pregnant women. "

Here's what the EPA says to do if a CFL bulb breaks in your home:

Before Clean-up: Air Out the Room

• Have people and pets leave the room, and don't let anyone walk through the breakage area on their way out.
• Open a window and leave the room for 15 minutes or more.
• Shut off the central forced-air heating/air conditioning system, if you have one.

Clean-Up Steps for Hard Surfaces

• Carefully scoop up glass pieces and powder using stiff paper or cardboard and place them in a glass jar with metal lid (such as a canning jar) or in a sealed plastic bag.
• Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder.
• Wipe the area clean with damp paper towels or disposable wet wipes. Place towels in the glass jar or plastic bag.
• Do not use a vacuum or broom to clean up the broken bulb on hard surfaces.

Clean-up Steps for Carpeting or Rug

• Carefully pick up glass fragments and place them in a glass jar with metal lid (such as a canning jar) or in a sealed plastic bag.
• Use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder.
• If vacuuming is needed after all visible materials are removed, vacuum the area where the bulb was broken.
• Remove the vacuum bag (or empty and wipe the canister), and put the bag or vacuum debris in a sealed plastic bag.

Clean-up Steps for Clothing, Bedding and Other Soft Materials

• If clothing or bedding materials come in direct contact with broken glass or mercury-containing powder from inside the bulb that may stick to the fabric, the clothing or bedding should be thrown away. Do not wash such clothing or bedding because mercury fragments in the clothing may contaminate the machine and/or pollute sewage.
• You can, however, wash clothing or other materials that have been exposed to the mercury vapor from a broken CFL, such as the clothing you are wearing when you cleaned up the broken CFL, as long as that clothing has not come into direct contact with the materials from the broken bulb.
• If shoes come into direct contact with broken glass or mercury-containing powder from the bulb, wipe them off with damp paper towels or disposable wet wipes. Place the towels or wipes in a glass jar or plastic bag for disposal.

Disposal of Clean-up Materials

• Immediately place all clean-up materials outdoors in a trash container or protected area for the next normal trash pickup.
• Wash your hands after disposing of the jars or plastic bags containing clean-up materials.
• Check with your local or state government about disposal requirements in your specific area. Some states do not allow such trash disposal. Instead, they require that broken and unbroken mercury-containing bulbs

Big advancement

[rift321]

I'm not sure everyone is completely aware of how big an advance this is. I'm going to buy Philips' stock as soon as I can. I'm sorry people have been screwed by some misleading marketing, but LEDs are the future of lighting... and the big green movement.

And yes, they're really easy to dim, either by converting to DC and modulating current, or by using a PWM - I'm not sure which is more efficient/cheaper.

I can't wait for CFLs to go away. Eventually you'll see commercially available, color-selectable LED bulbs.

Anyone know if the process was patented/sold to a specific company? Pretty obvious why...

Ahh, 5 years...

[PowerVegetable]

The good ole' 5-year technology promise. Close enough to be exciting and get attention, but far enough away that you'll forget about their claim before they miss their deadline.

Ok, let's get this thread straightened out.

[hey!]

(1) LEDs can in fact be dimmed by running less current through them, however their power efficiency drops, which negates the whole purpose of LED lighting. The most efficient way to dim an LED is to strobe it on faster than the human eye can detect By varying with fraction of the on/off cycle that the LED is on, the human eye perceives this as "dimmer". The number of photons averaged over a second is reduced, but for the milliseconds the LED is on it is at full brightness.

(2) Incandescent bulb dimmers are almost never been rheostats, not since maybe the 1920s. The problem is efficiency again. Imagine a certain current flowing through the light bulb and the rheostat; the power dissipated in each device is then proportional to the resistance. When the rheostat is at equal resistance to the light bulb, it is dissipating as much power as the light bulb is! A 100 watt light bulb at 50% of the normal RMS current dissipates 25 watts, which means your rheostat is getting as hot as a small soldering iron. You'd need a massive heatsink to handle this.

Therefore for many years, dimmers were not very practical. The best dimmers were actually transformers, but they were extremely bulky. They were mainly used in theaters and fancy restaurants to soften the shock of the prices on the menu by relief at being able to find them at all.

With the creation of the solid state silicon controlled rectifier (scr), it is possible to do a trick with incandescent bulbs that is rather like the LED strobing trick. What you do is you take the sine wave power and you clip out the parts of the waveform on either side of the peak. So rather than having power delivered to light bulb all the time, the light bulb is only powered for a fraction of the cycle. The difference is that an incandescent filament glows because it is hot; it does not flicker on and off.

Now with respect LED light bulbs, I'm not sure about what circuitry they contain, but they do contain circuitry. If you just plugged enough LEDs in series to plug straight into AC, they'd flicker at a very noticeable 60Hz. If you put a full wave rectifier into the circuit, they'd flicker at 120Hz, which might be fast enough you wouldn't notice the flickering. You'd certainly be able to use the a solid state dimmer to dim such as circuit, but flickering might be noticeable.

There are relatively simple tricks you could use to maybe double the frequency, in which case you probably would not be able to perceive the flicker. On the other hand, there might be fancier circuits that know how to do the right thing. One of the problems with LEDs is that they age, their brightness varies. If the LED bulb achieves its white color by using several different colors, you need a compensating circuit to maintain the original color.

Of course you could use white LEDs, but most of the bright ones are very harsh; I've seen warm white LEDs advertised, but I've never had one.

So there you go, the straight facts on dimming that every geek should know.

Re:My first experience with LED lighting...

[rolfwind]

+ disposing them is order of magnitude worse than conventional lightbulbs.

Any home depot accepts any and all CFLs. In fact, it's easier and cheaper to dispose of CFLs properly than it is of Fluorescents.

Oh, and if your electricity is generated from coal, you are helping put mercury in the air as well.

Re:My first experience with LED lighting...

[stonefry]

And who exactly wants to live in something that resembles a hospital?

Your friendly neighbourhood CDO neat-freak???

Fixed it for you. The letters are now in alphabetical order. LIKE THEY SHOULD BE!

Re:We need lumens ratings

[dr2chase]

Not so for LEDs; their peaks are substantially less sharp. I verified this both with a physicist, and with a diffraction grating. I took pictures, too. One problem you get, is that the "highest lumen" LEDs have a spectrum similar to an arc-welder, and it's not so nice. I used some good-quality neutral-white CREE LEDs for kitchen counter lighting, and it is quite nice.

Re:My first experience with LED lighting...

[camperdave]

I don't trust lumens either. The lumen output of CFL lighting halves every foot or so from the light source.

It's worse than that, mate. Every time you double the distance, the brightess goes down by a factor of four! So, two feet away, the bulb is a quarter as bright as it was a foot away.