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Fluorouscent lamp for Overhead projector

Discussion in 'Electronic Design' started by [email protected], Nov 21, 2004.

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  1. Guest


    Sorry for a stupid question.

    I was looking at the LCD+OHP DIY projects and was wondering why don't
    OHPs use fluoroscent lamps to maintain lower temperatures? Don't they
    make FL lamps in the 3200-4000 lumen range or are they much more
    expensive than incandescent lamps in that lumen range?

  2. Rich Grise

    Rich Grise Guest

    Hi, Sid.

    It's because fluorescents give a diffused light. This is good for a
    lightbox, where you're the only one to look at it, but for projecting the
    same transparency, it's much more efficient to collimate a point source
    and let the screen do the diffusing.

    Hope this Helps!
  3. Guest

    Thanks Rich.

    - Siddhartha
  4. Projectors require very compact, concentrated light sources. Halogen
    lamps with filament temperature pushed to around 3300 K (with life
    expectancy usually less than 100 hours) are "low end" for accomplishing
    this task...

    Fluorescent lamps that put out about 3,000 lumens (or a bit less) are
    nearly 4 feet or roughly 1.2 meters long and 1-1.5 inches (2.5-3.8 cm) in
    diameter - how much of their light will be utilized by a projector?

    - Don Klipstein ()
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