LCD TV

LCD systems are reflective systems. Rather than emit fight, LCDs use crystals that reflect fight. That is why your digital watch, which uses an LCD, may have a light so that you can illuminate the watch face to read the time when it is dark.

LCDs work by using electric fields to twist the liquid crystal molecules. The standard LCD watch twists the LCD crystals to about 90 degrees from their normal position which makes the crystals nonreflective; they appear as black on a silver background, just as the numbers on the face of a digital watch. A rough analogy to this system would be the card section at a college football game. Each member of the card section would represent one crystal. Suppose each member starts by holding up the silver side of his or her card this would be analogous in the LCD to a state with no electric current flowing. Now suppose a selected number of members flip their cards over to the black side, forming an image. This would represent what happens in the LCD when an electric current reaches some of the crystals. Varying the electrical voltage to the crystals would produce a series of images that would form a TV picture.

LCD flat screens are useful as portable televisions outside because the brighter the sunlight the better the picture. For inside use, extensive illumination is necessary to see the image. The darker the room, the poorer the image. Color LCD screens have been built for consumers, but the largest screen is less than 7 inches measured diagonally. Full size, color LCD screens for the home have yet to be developed.

The newest technology in the race for flatscreen television is microtip TV, or the Spindt cathode. A product of microminiaturization techniques

The liquid crystal display (LCD) panel makes flat screen television possible. The Minch screen pictured here is just over 1 inch thick developed for microchips, microtip TV replaces the one to three big cathode guns at the back of the picture tube with thousands of microminiature ones, making possible a supersharp image on a flat display panel.