slebans
Enlightened
http://www.ledinside.com/cree_254lm_per_w_201204
Just another 'Cree Labs' press release -but one can always hope!
Stephen Lebans
Just another 'Cree Labs' press release -but one can always hope!
Stephen Lebans
Sounds awesome. It would be even better if we could actually get them. They should send us some for testing. Lets forward this thread to Cree.
Room temperature is usually 68F. But can be up to 72. So I guess anywhere in between there.
At the efficiency this LED is operating at, junction temperature is probably within a few degrees of room temperature. I'm estimating around 90% WPE for the primary blue emitter.
I assumed a LER of 340 lm/W. This gives an overall WPE of 254/340=~75%. I further assumed a combined phosphor conversion efficiency/package efficiency of around 83% (this is about the highest number I've heard for phosphor white LEDs). Therefore, WPE of the royal blue emitter ~ 0.75/0.83 = ~90%.Are you basing this on a straight line approximation of the published XT-E Royal Blue specifications?
Cree XT-E Royal Blue
53% WPE
Cree XT-E Cool White
148 lm/w
148 / 254 = .5826
53% / .5826 = 90.97% WPE
Does this not assume that the Royal Blue LED underlying the XT-E White LED has the same WPE as the XT-E Royal Blue LED? I always thought that Cree held back the highest Bins of their Royal Blue LEDs for their own production of White LEDS of the same families. In fact, I'm quite sure I acquired this information from an older post of yours. I found the assumption logical in that Cree would never want a third party to be able to repackage a Royal Blue in a configuration where the efficacy of the resultant White LED would exceed Cree's own product of the same family.
Alternatively, is your estimate simply based on a LER value of 350 lumens per watt?
254 /350 = 72.5% WPE
Add back on original Phosphor/Package losses of 20%(90% x .2 = 18%)
72.5% + 18% = 90% WPE
I hate guessing. I wish these CREE R&D press releases contained more detailed information.
I wished they released the 208lumen/watt revealed 2 years ago instead of wasting R and D money on prototypes. I means prototypes are useless without production. On the plus side, the colour temperature of sub 5000k is very good, a nice departure from cool whites being more efficient.
I wished they released the 208lumen/watt revealed 2 years ago instead of wasting R and D money on prototypes. I means prototypes are useless without production. On the plus side, the colour temperature of sub 5000k is very good, a nice departure from cool whites being more efficient.
Let's please keep the 'Cree stock' discussion to the 'Cree Stock' thread, thanks.Bottom line, the investors aren't impressed. Look what Cree stock has done in the last two years; almost tanked. The investor fervor that drove Cree for a few years appears gone.
If it continues trending as it is, we should approach or exceed 300 lm/W in about 2 years
Yes, I meant 300 lm/W in the lab. Nichia said this was possible last year I think. I know they hit around 265 lm/W at a few mA, and the blue emitter they were using had a WPE in the high 80s.He may have been referring to just the LED efficacy. But I definitely agree with you in that we won't see 200lm/W in the next two years on the market. And as for the 300lm/W I don't think that can be accomplished due to theoretical limits for efficacy of about 270lm/W. I might be a little off on that but pretty sure it is below 300lm/W.
when the 200 L/W LEDs get out there in mass production perhaps we can start seeing LED bulbs/fixtures sold in stores that sport 120 L/W figures and start comparing themselves to fluorescent lighting instead of incan.Yes, I meant 300 lm/W in the lab. Nichia said this was possible last year I think. I know they hit around 265 lm/W at a few mA, and the blue emitter they were using had a WPE in the high 80s.
Seeing the lag of ~4 years between R&D and production LEDs, we probably won't see 200 lm/W in production until at least 2014.