LCD TV is a flat panel television that utilizes the same basic Liquid Crystal Display technology that has been in used for some time in cell phones, camcorder viewfinders, and computer monitors.

LCD panels are made of two layers of a glass-like material, which are polarized, and are "glued" together. One of the layers is coated with a special polymer that holds the individual liquid crystals. Electric current is then passed through individual crystals, which allow the crystals to pass or block light to create images.

LCD crystals do not produce their own light, so an external light source, such as florescent bulb is needed for the image created by the LCD to become visible to the viewer.

Unlike standard CRT and Plasma televisions, there are no phosphors that light up, and, thus LCD panels are thin and require less power to operate.

Combining the above technology with the features of a traditional television, such as, AV input/output connectivity, side or bottom mounted loudspeakers, TV tuner, and traditional television adjustment controls, bring to life a concept that is becoming a popular option for TV and home theater viewing.

                                                                             

Plasma television technology is similar to the technology used in a fluorescent lightbulb. The display itself consists of cells. Within each cell two glass panels are separated by a narrow gap in which neon-xenon gas is injected and sealed in plasma form during the manufacturing process. The gas is electrically charged at specific intervals when the Plasma set is in use. The charged gas then strikes red, green, and blue phosphors, thus creating a television image. Each group of red, green, and blue phosphors is called a pixel (picture element).

This technology is different from that of a traditional television. A traditional television has a Cathode Ray Tube, or CRT. A CRT is basically a large vacuum tube in which an electronic beam, emanating from a single point in the neck of the tube, scans the face of the tube very rapidly, which, in turn lights up red, green, or blue phosphors on the tube's surface in order to create an image.

The main advantage of Plasma over CRT technology is that, by utilizing a sealed cell with charged plasma for each pixel, the need for a scanning electron beam in eliminated, which, in turn, eliminates the need for a large Cathode Ray Tube to produce video images. This is why traditional televisions are shaped more like boxes and Plasma televisions are thin and flat.

DLP Real Projection

The most promising heir to the CRT-based rear-projection television in use today is the DLP (Digital Light Processing) rear-projection television. Like LCD, the actual image is displayed on a chip, however, the chip used in a DLP projection television is different. The chip in a DLP projection television is referred to as a DMD (Digital Micromirror Device). In essence, every pixel on a DMD chip is a reflective mirror.

The video image is displayed on the DMD chip. The micromirrors on the chip (remember: each micromirror represents one pixel) then tilt very rapidly as the image changes. This process produces the grayscale foundation for the image. Then, color is added as light passes through a high-speed color wheel and is reflected off of the micromirrors on the DLP chip as they rapidly tilt towards or away from the light source.

The degree of tilt of each micromirror coupled with the rapidly spinning color wheel determines the color structure of the projected image. As the amplified light bounces off the micromirrors, it is sent through the lens, reflected off a large single mirror, and onto the screen. For further technical explanations, click on the DLP resource link on the upper right sidebar of this page.

The second type of rear-projection television technology to consider is LCD (Liquid Crystal Display) projection (not to be confused with LCD flat panel television). Unlike a CRT projection television, the LCD-based rear projection television is not based on the traditional projection tube. A rear-projection LCD television 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.

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 traditional CRT-based rear-projection sets. Although you can't hang 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.

Other advantages of rear-projection LCD technology are its high contrast and brightness capability, as well as lower power consumption.