Difference between CRT TVs & RPTV

Discussion in 'General TV Discussions Forum' started by Comer, Sep 24, 2001.

  1. Comer

    Comer
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    I'm just curious, but what is the difference between CRT tvs and rear proj tvs

    Thanx

    Conor
     
  2. damjanb

    damjanb
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    Part of the answer is contained in<br />the name: projection TVs project<br />the image. More precisely, they<br />project three images: one red, one<br />green, one blue. These overlap on<br />the screen, making up a full color<br />image. Instead of one large tube<br />(in which the three images are<br />adjacent), there are three small<br />ones. They give off light into<br />lenses, which project the three<br />images onto a mirror. In it, you<br />see the composite image through<br />a screen which is made up of<br />further optical elements<br />(planar lenses).
     
  3. damjanb

    damjanb
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    PS: So "rear projection" because the<br />mirror works like a rear-view mirror,<br />in which you see the image(s) on the<br />tubes, magnified by the projection<br />distance. The tubes are in the base<br />of the set and project up and away<br />towards the rear, where the mirror<br />is, inclined at about 45 degrees.
     
  4. Comer

    Comer
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    Thanks

    So do all rear proj tvs have a CRT projector shooting up at the screen via this mirror?

    Conor
     
  5. damjanb

    damjanb
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    &gt; So do all rear proj tvs have a CRT<br />&gt; projector shooting up at the screen<br />&gt; via this mirror?<br />Uuups, i did leave that distinct<br />impression, but it ain't so, not<br />anymore: instead of CRT primaries<br />(red, green, blue), they can have<br />LCD ones, like some Sony models,<br />or DLP, like, hmmm, nothing in Europe<br />(but Mitsubishi in the States).

    I think some cheap ones even have<br />one primary only.
     
  6. damjanb

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    &gt; I think some cheap ones even have<br />&gt; one primary only<br />&gt;<br />Got a little carried away again: some<br />expensive ones also have one primary,<br />the DLP ones;<br />there, the colors come one after the<br />other onto the screen;<br />so, there are three ways in which<br />primary color images can form a<br />full color image: they can be<br />- adjacent in space (classical TV)<br />- adjacent in time (DLP)<br />- at same space, same time (CRT RPTV)<br />(so, the third variant has the best<br />disposition for maximal resolution)
     

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