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Cree 100 lm/W LED

Discussion in 'Lighting' started by Victor Roberts, Mar 5, 2005.

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  1. According to the following press release Cree has demonstrated a 100
    lm/W LED with what they call 50% wall plug efficiency.

    http://www.cree.com/News/news214.asp

    However, I can't find any data on the Cree Web site that supports this
    claim. They _could_ be talking about a green LED, but then the 50%
    number would be wrong. The eye sensitivity in the green is abut 683
    lm/W so 50% efficiency would mean 341 lm/W, not 100 lm/W. The
    combination of 100 lm/W and 50% efficiency implies white light, since
    200 lm/W is often used as the maximum efficiency of a "white" light
    source.

    Does anyone have more information about Cree's claim?

    --
    Vic Roberts
    http://www.RobertsResearchInc.com
    To reply via e-mail:
    replace xxx with vdr in the Reply to: address
    or use e-mail address listed at the Web site.
     
  2. "50% wall plug efficiency" Is that like 1000W Peak Music Power Output?
     
  3. It is not clear what they mean here, but the term "wall plug efficacy"
    is well understood to mean the efficacy of the light source and its
    associated ballast or power supply.

    --
    Vic Roberts
    http://www.RobertsResearchInc.com
    To reply via e-mail:
    replace xxx with vdr in the Reply to: address
    or use e-mail address listed at the Web site.
     
  4. My guess this was a demonstration prototype made with a chip that is
    either not yet in production or was a production one where variations due
    to tolerances went favorable. However, I cannot yet rule out unusual
    operating conditions.

    The best chips in any datasheets that I found so far in Cree's website
    produce 24 mW of blue light from 68 mW of electrical input if I remember
    correctly - that's 35% "wallplug efficiency".

    - Don Klipstein ()
     
  5. If that is 68 mW into the LED I would argue that is NOT wallplug
    efficiency since the power supply losses are not included. However, as
    with "full spectrum" wall plug efficiency is not a term defined by any
    standards organization so I guess they are allowed to make up any
    definition that supports their advertising objectives.

    --
    Vic Roberts
    http://www.RobertsResearchInc.com
    To reply via e-mail:
    replace xxx with vdr in the Reply to: address
    or use e-mail address listed at the Web site.
     
  6. Perhaps they're measuring in internet inches.


    -DS, thinking of those Chinese "3 million candlepower" flashlight lanterns
    you can buy for $18 from Wal-Mart, that use a 6v 6w bulb...
     
  7. I measured the optical output of one of those lamps and it actually
    exceeded 3 million candlepower. Mind you, it didn't last too long
    across 240V. :)
     
  8. I agree there. I think they should use "conversion efficiency". Then
    again, they don't say "wallplug" on the chip datasheet. But then again
    then again I am guessing where they do use the word "wallplug" they either
    mean conversion efficiency or else have the most efficient ballast they
    can get their hands on.

    But if an LED adoes produce 100 lumens of white light per watt of
    electricity that gets delivered to the LED, that's still awfully good and
    I wonder when I get to get one!

    - Don Klipstein ()
     
  9. I have noticed one brand of lower cost ones with higher brightness
    numbers and often more than one model on the shelf, and that lately:

    They no longer use the word "candlepower" with the big number, but
    "power series". At least at Target I noticed this.

    - Don Klipstein ()
     
  10. You may have noticed that the e-mail address listed for more info on
    the press release has no domain name. I plan to call them on Monday
    and try to get more info. I don't think this is real, but would like
    to figure out what combination of number they put together to make
    this claim.

    --
    Vic Roberts
    http://www.RobertsResearchInc.com
    To reply via e-mail:
    replace xxx with vdr in the Reply to: address
    or use e-mail address listed at the Web site.
     
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