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101 Gadgets That Changed The World

Discussion in 'Lighting' started by Jeff Engel, Aug 9, 2011.

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  1. Jeff Engel

    Jeff Engel Guest

    This is a Popular Mechanics tribute to LEDs. Are the facts true or false?

    31. LED Russian Oleg Vladimiovich Losev invented the first LED in 1927,
    though no practical use was found. Nick Holonyak, Jr., of GE pioneered
    the first practical visible-spectrum LED, in 1962. Since then, LED
    efficiency has doubled every 36 months.

    Read more: 101 Gadgets That Changed The World - Top 101 Gadgets of All
    Time - Popular Mechanics
  2. How far has the efficiency of LEDs doubling every 3 years persisted
    into recent years? How long is that trend expected to continue?

    I am aware of a white LED laboratory prototype achieving close to 60%
    radiometric efficiency about a year ago.
    And, I am aware of production units of white LEDs that I purchased over
    1.5 years ago achieving about or 40% efficiency at 20 mA, and rated
    supposedly to achieve typically 150 lumens/watt at 20 mA. (I "measured"
    these as best as I can, and found 140 lumens/watt, some fair chance

    Market appears to me to be 2-3 years behind laboratory prototypes, maybe
    4 or so lately.

    Laboratory prototypes in warmer colors and higher color rendering
    versions are behind "cold white" versions.

    Over 6 months ago, I purchased an LED claimed to typically achieve
    160 lumens/watt of "white" light at 350 mA - likely at least 45%
    efficiency, 42% "in real world" if that claim is not falsified?

    Yet, can I expect a LED laboratory prototype of any color or any color
    rendering index 2-2.5 years from now to have radiometric efficiency of

    I expect the improvement from now is higher efficiciency in warmer
    colors and higher CRI, with cost reduction to successfully compete against
    non-LED lighting technologies. And I suspect some of this has already
    been accomplished but is still "work in progress", according to my
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