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| CRT Video Projection Technology |  When rear-projection televisions first appeared on the scene, television technology was based on the CRT (Cathode Ray Tube) Projection System. The operation of CRT Projection system is based on three small CRTs (one for each primary color), coupled with a light magnifying lens, projects a color image onto a mirror and is then reflected onto a screen. A CRTs can create perfect high resolution images with the proper video processing circuitry, CRT size, and lens combination.
Benefits of CRT Video Projection
1. A CRT is basically a large vacuum tube in which an electron beam, emitting from a single point in the neck of the tube, scans the face of the tube very quickly, which, in turn lights up phosphors on the tube's surface in order to produce an image. A CRT created image is not limited to a fixed pixel field, as are other rear projection types. This makes the CRT-based video projection possibly the best option where the flexibility of displaying changeable resolutions is the main consideration.
2. CRT-based rear-projection technology can create the blackest blacks of all projection types as well as the full range of color, and brightness, giving a CRT projector the ability to create the most film-like images of projectors for home use (up to this point).
3. CRT-based rear-projection televisions are cheap to manufacture, because they are based on technology that has been around for decades. Thus, prices of CRT-based rear-projection televisions are several hundred dollars less than their DLP and LCD rear-projection counterparts (screen size and features being equal).
Limitations of CRT Video Projection
1. A CRT projection television is rather big-size. A CRT-based projection television can occupy a lot of space, in terms of cabinet depth, not only in comparison to Plasma and LCD flat panel sets, both also in comparison to DLP and LCD rear-projection units.
2. The best image reproduction in CRT-based rear-projection television is provided with properly converging. The red, green, and blue tubes which are contained in current CRT-based rear-projection television need to be aligned so that the projected image does not show color halos and the colors are mixed in a proper way. If one projection tube breaks, all three have to be changed in order to offer the correct color and brightness balance.
3. Although all projection televisions generate some heat, this is a problem for CRT-based projection sets, because three separate projection tubes must be cooled and kept at an even temperature. This is reached by liquid gels developed for this purpose. Although very rare, the liquid gels casings can leak, thus causing the television to malfunction.
4. CRT projection televisions are more sensitive to image burn-in from continuously displayed station logos and window box lines resulting from extensive display of 4x3 programming on 16x9 CRT projection sets.
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