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| LCD Video Projection Technology |  The LCD (Liquid Crystal Display) Projection System is one of the type of rear-projection television technology shouldn’t be confused with LCD flat panel television. The LCD-based rear projection television is different from a CRT projection television as it is not based on the traditional projection tube. The work of a rear-projection LCD television is based on 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.
Benefits of LCD Video Projection
1. The LCD chip is very small and this fact makes the LCD projector assembly very practical and compact.
One LCD chip is hundreds of times smaller than the three projection tubes needed in CRT-based rear-projection televisions. This means that LCD-based rear-projection televisions can be made a lot thinner and lighter than conventional CRT-based rear-projection sets. Although you can't place it on the wall like you can with an LCD flat panel or Plasma Television, you can still save a lot of floor space, and spend less money than you would buying that stylish LCD flat panel or Plasma set. In addition, since these are projection sets, you can get one in larger screen sizes than you can with either LCD or Plasma flat panel types.
2. Other benefits of rear-projection LCD technology are its high contrast and brightness capability, as well as lower power consumption.
Limitations of LCD Video Projection
1. A LCD projection television can often times demonstrate what is called "the screen door effect". Since the screen is made up of individual pixels, the pixels can be visible on a large screen, thus giving the appearance of viewing the image through a "screen door".
2. LCD rear-projection televisions, although appearing to be simpler in structure, thanks to the use of a small chip, rather than three CRT tubes, are still much more complex to create than conventional CRT projection televisions. This is due to the higher cost of manufacturing the LCD chips themselves. Thus, LCD-based rear-projection televisions are usually several hundred dollars more than their CRT-based counterparts (with size and features being equal).
3. An LCD chip consists of individual pixels. It means that if one pixel burns out it displays an irritating black or white dot on the projected image. If one or more pixels burn out, the entire chip has to be changed as individual pixels cannot be mended.
4. Since LCD chips have a limited number of pixels, signal inputs that have higher resolutions must be scaled to fit the pixel field count of the particular LCD chip. For instance, a normal HDTV input format of 1080i needs a native display of 1920x1080 pixels for a one-to-one display of the HDTV image. However, if your LCD chip only has a pixel field of 1024x768, the original HDTV signal must be scaled to fit the 1024x768 pixel count on the LCD chip. This is where CRT-based rear-projection sets can surpass an LCD rear-projection set. Since CRTs are not limited by a fixed pixel field, they are more flexible at displaying various resolutions, due to being able to variably scan the image onto the projection tube surface.
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