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Cree Introduces 200 Lumen/Watt Production Power LEDs
ndverdo writes "Cree just announced production power LEDs reaching 200 lumen/watt. Approximately doubling the previous peak LED light efficiency, the new LEDs will require less cooling. This should enable the MK-R series to finally provide direct no-hassle replacements to popular form-factors such as MR-16 spots and incandescent lighting in general. The LEDs are sampling and it is stated that 'production quantities are available with standard lead times.'"
Kudos.
The reduced cooling should help in lowering the costs of the LED versus the CFL and the reduced energy consumption will be a help as well.
A Shadeless room is a brighter room.
...seems to have the expert analysis. Some people are into flashlights so much and the LEDs that may be used in them, it's crazy what details they keep tabs on.
Post on the Cree MK-R LED at Candlepower Forums.
I am sick and tired... of the government banning perfectly good items
Then consider yourself in luck! Because, y'know, TFA has nothing to do with anyone banning anything. Don't let me interrupt a good rant, though - Carry on, good sir, you rage against that machine!
Some of us would rather spend our money on more fun things than literally "keeping the lights on". Do whatever you want with your money.
When someone talks about "X Kelvin" as a colour temperature, they mean the spectrum emitted by a black-body at that temperature, which by definition is full-spectrum.
To a first approximation the sun emits radiation at 5800K.
If only! "An upper limit for incandescent lamp luminous efficacy (LER) is around 52 lumens per watt, the theoretical value emitted by tungsten at its melting point" (wikipedia). In fact a 40W tungsten bulb outputs 12.6 lumens/watt, up to 17.5 for a 100W bulb. Incandescent bulbs aren't even in the ballpark anymore.
As to whether some people assume all light is equal, I suppose some do. But others take it very seriously. It is not an overlooked issue.
Wikipedia has a list of luminous efficacies:
http://en.wikipedia.org/wiki/Luminous_efficacy
200 lm/W seems pretty good; the theoretical limit is around 300 lm/W for LEDs, and that's about 44% overall efficiency.
While it indeed is a commercial product, it's also a new industry milestone.
While I *do* love to hear stories like this, and I believe that LED lighting, in some form, is the future, it dissappoints me to see that so-called "white" LEDs still produce quite poor spectra. Check out the spectrum on page 4 of the datasheet given on the MK-R series page. Compare this to the sun's spectrum. Because these are phosphor-based LEDs, you get a relatively narrow blue-violet peak (the true colour of the LED), followed by a wider hump, peaking at about yellow (the broad emission spectrum of the phosphor coating, which is down-converting those blue photons). While this looks "pure white" when you look directly at the beam, it renders colours very poorly (i.e. the reflected light from objects looks the wrong colour). This is what causes LEDs and fluorescent lights to often make a room appear sickly and food look unappetizing. Ideally, we should strive for a light which closely emulates the sun's spectrum, but this is obviously challenging.
Fortunately, there are a few next-gen LED technologies on the horizon. Quantum dot-based LEDs seem promising. By making dots of a specific size, you can precisely tune the output wavelength of a QD LED. Presumably you can combine a whole bunch of QD LEDs, each tuned to a different wavelength, to approximate the sun's spectrum. Alternatively, certain types of organic LEDs offer the ability to tune the wavelength, and similarly, produce a composite device which has a more ideal spectrum.
Still, until these materialise, plain 'ol incandescents are the only cheap light sources which produce a nice, continuous blackbody spectrum. Sigh.
It's way, way, way more complex than this.
683lm/W is the maximum luminous efficacy for light, yes, but that's green light.
To reproduce in full the solar spectrum so that it is indistinguishable from white light requires you to produce a 'white' that produces light from about 400-700nm (UV to IR borders).
If you take into account flourescence and its effect on colour, perhaps 350nm is the top end.
This would take perhaps 180lm/W.
As you move from near-solar (or tungsten) identical bulbs to more limited 'whites' - you get about 250-400lm/W being the maximum.
This varies from pretty good white that you won't notice being different from actual white to something rather more limited, with just blue at 430nm or so, and greenish yellow at 560nm.
This will to a cursory glance look right, but will have truly wretched colour reproduction.
this Cree MK-R isn't super suitable for torches
Certainly not suitable. It produces less heat than other LEDs, which are themselves not even suitable. For my torches i tend to stick to propane, MAPP, and acetylene.
A year ago, I had no idea who "Cree" might be.
Then I bought one of these:
http://www.fenixlight.com/viewproduct.asp?id=151
It's the best pocket flashlight I have ever owned. Bright and useful on "low" power (32 Lumens) and very bright on high (105 Lumens). 500 minutes of light (over 8 hours) from a single AA cell on low, or 110 minutes on high. (I'm trusting the manufacturer's numbers here, but I can verify that it actually is bright and lasts a long time.) Anyway, that's a Cree LED, and it doesn't have the horrible bluish tint of older LEDs I have bought in the past.
More recently I bought an Ecosmart light bulb at Home Depot. "Ecosmart" is a Home Depot house brand, and uses Cree LED chips. For $10 I got a light bulb that claims to give equivalent light to a 40 Watt incandescent bulb, but seems brighter than that (I think because it's much more directional; it's in a downward-facing fixture so that's fine).
http://www.homedepot.com/h_d1/N-5yc1v/R-202188260/h_d2/ProductDisplay?catalogId=10053
And just two days ago I got a fixture that retrofits a 6" can fixture with an LED light. I bought one with the 2700K color temperature, because I like that better than the "colder" lights (bluer, which actually have higher color temperatures). I walked into the store planning to just buy a bulb for my can light fixture, and now I'm very glad I bought the whole Ecosmart fixture. I found an LED light geek web site, and the guy bought one of these just to do a teardown; he found 5 Cree LED chips inside it. Where I live, the power company is subsidizing these lights, so I only had to pay $20 for this light. This dissipates only 9.5 Watts, yet it's very bright. I love the design: it includes three spring fingers to hold it into place, but if you rotate it the fingers collapse and stop holding it. So two decades from now when the LED stops working, it will be easy to remove.
http://www.homedepot.com/h_d1/N-5yc1v/R-202240932/h_d2/ProductDisplay?catalogId=10053
So now I want to see Cree make some sort of flush-mount ceiling fixture. I have only found a few flush-mount LED fixtures, and they are all super expensive and I can't find the 2700 K color temperature. I did find one promising looking cheap fixture, but on eBay only and it's an import from China... I have no way to be sure of the quality, other than just buying one and trying it.
My current plans are just to install some fixtures that have air gaps for circulation, so I can use the Phillips LED bulbs (omnidirectional, not directional like the Ecosmart ones). I'm going to install one of these tomorrow and see how we like it. In case the URL doesn't work right, this is a "Project Source 2-Pack White Ceiling Flush Mount" from lowes.com.
http://www.lowes.com/pd_394606-43501-87822-01_0__?productId=3745415
Based on my experience with these lights, we are just on the cusp of these becoming mainstream and common. I've been buying these because they are subsidized, but electronics always gets cheaper over time, and within a couple of years or so LED lights should be cheap enough without subsidy that everyone starts buying them. (Even without the subsidy, they make sense long-term versus incandescent bulbs. If you have incandescent lights, consider LED rather than compact fluorescent.)
P.S. I haven't bought these, but I wish the office where I work would buy them. These are Cree replacement lights for standard fluorescent fixtures. Some companies are making LED lights that are the exact size of a T8 fluorescent bulb, with matching pins; for $60 or $80 or so each bulb, you can replace fluorescents (but you must rewire the fixture to bypass the ballas
lf(1): it's like ls(1) but sorts filenames by extension, tersely
To continue the comparision: The theoretical maximum you could get out of a light source is about 251 Lumen/Watt for a source of white light at 5800 K. So this new type of LED is near 80% efficiency.
When I started working with LEDs they just introduced the LM3909 oscillator - it allowed an LED (only red in those days) to blink for an entire year on a single D cell.
What keeps amazing me about LEDs is just how little energy they need to start lighting up. I'm not really into electronics anymore (was only tinkering with it since I was 11), but I recall that by using a FET for constant current meant you could be pretty flexible about the supply voltage (within limits, of course, the dissipation has to go somewhere), and by researching what it was (been a while) I came across other interesting ideas.
As a single, simple component, I find LEDs are about the most interesting ones to experiment with (and LDRs, and NTCs, and .. :) ). They are nice to introduce children to electronics because they instantly do something visible..
Insert
On my bicycle I use a 30 or 40 year old chrome headlight made for use with a dynamo.
I replaced the 6v 2.4watt filament bulb in it with a high power white MES LED module designed to have 100 degree illumination. Powered by a single PP3 radio battery under the saddle, it produces a 15 foot cone of light on the road ahead of me lighting everything up to handlebar height (yes, I'm overvolting a 6v LED module but it doesnt seem to cause any problems, it still runs cool)
I have been a user for about 10 years. This ends Feb 2014. The site's been ruined. I'm off. Dice, FU
I've noticed a disturbing trend. Car manufacturers have been using the new lightning technologies to cram e.g. the headlights into ever smaller spaces. The resulting light beam still conforms to regulations, but because the peak intensity is much higher, those headlights are much more likely to dazzle oncoming traffic. The higher the light intensity of the lamp (lm/cm^2) the worse this will get.