Why do you need a lamp for LCD's?

Discussion in 'Displays' started by Mike JM, Jul 22, 2006.

  1. Mike JM

    Mike JM Stunt Coordinator

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    I have an LCD computer monitor. And as far as I know, I won't have to replace the lamp cause there isn't any.

    Why are there lamps for LCD televisions?

    DLP has a lamp for the color wheel. right? But why LCD?

    So only plasmas don't require bulb replacements?

    thanks.
     
  2. Alon Goldberg

    Alon Goldberg Screenwriter

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    Hi Mike - LCD Rear Projection (not to be confused with LCD flat panel television or computer monitor) basically works by passing a powerful light source through a transparent LCD chip made up of individual pixels (which displays the moving video image) and projecting that image through a magnifying lens, to a mirror, which then reflects that image, onto a screen.

    Both LCD Rear Projection and DLP Rear Projection televisions require bulb replacement, typically every 3-5 years.
     
  3. Steve Berger

    Steve Berger Supporting Actor

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    An LCD is a passive device and requires light to pass through it to produce a picture. A DLP needs light bounced off of it. Your PC monitor has one or possibly two (non consumer replaceable) lamps in it. It could also have an EL (electroluminescent) panel, also not consumer replaceable.

    A flat panel requires an even source of light but does not need as much intensity as a front or rear projector (PJ). High intensity equals high heat and relatively short life. The light source on a flat panel has a lifespan similar to the life of the panel while the life of a PJ light source is much less that the life of the panels or image device, hence the need for replacement.
     
  4. Leo Kerr

    Leo Kerr Screenwriter

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    And actually, your PC's LCD monitor does have a lamp. Actually, it very likely has several lamps - cold-cathode or flourescent tubes line the edges (for smaller screens) or are spaced at fairly tight intervals directly behind larger screens generate the light fot the LCD screen to throttle.
     

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