264 Electronics Explained: The New Systems Approach to Learning Electronics In front of the liquid crystal is another transparent sheet containing the red, blue, and green pixels described earlier. The whole thing is sandwiched together in a very thin screen. The electrical signals applied to a matrix of wires cause the liquid crystals to be properly oriented for each pixel and to allow the correct proportion of light through to each of the red, blue, and green light filters. Plasma --A plasma screen is also made up of many tiny light sources. Each light source or subpixel is actually a small chamber containing xenon and neon gases. When a voltage is applied to each of these chambers, the gases ionize and emit ultraviolet light. The ultraviolet light then actually strikes a phosphor coated inside the chamber. The chamber then emits red, green, or blue light. The degree of ionization determines the brightness of each subpixel. In any case, electrical signals are then applied in sequence to the subpixels to turn them on with the correct degree of brightness to produce the desired color. DLP Digital light processing is a technique invented by Texas Instruments. -- The heart of it is an integrated circuit chip made up of hundreds of thousands or millions of tiny mirrors. The mirrors can be moved to one of two positions. This is an example of a microelectromechanical system (MEMS). MEMS is a tech- nique for making mechanical moving objects using semiconductor manufactur- ing techniques. Each of the tiny mirrors can be moved so that in one position it will reflect maximum light (representing white) and the other position where no light is reflected (representing black). You can then produce any shade of gray simply by switching the individual mirrors off and on at a high rate of speed. The light source is shined on the mirror and the resulting monochrome scene produced on the DLP chip is then focused on a screen from the rear by a lens system. To produce color, the light source is passed through a rotating disc with alter- nating red, green, and blue segments. The speed of rotation and the frequency of each color on the disc allow each mirror to then reflect a specific color of light. In the newer DLP screens, high-intensity red, green, and blue LEDs are used to send light to the mirrors, which are then mixed and projected onto the screen. LED The newest TV screens are made of tiny red, green, and blue light -- emitting diodes arranged in a pixel matrix as described earlier. The LED screens are the brightest available and respond fast to action scenes. However, they are the most expensive screens. 3D TV Yes, you actually can buy a 3D TV set that gives you that same 3D "coming- at-you" feeling of theater 3D. As this is written, these sets are very expensive and there is very little 3D material to see. Right now it is only available on DVD. Eventually it may be available by cable or satellite or over the Internet. And, yes, you still have to wear the special glasses. These glasses are not the red and green lens type but a special electronic version. The lenses use elec- trical polarization like a shutter that turns the left and right lenses off and on