Liquid Crystal Display (LCD) TV Systems

Liquid Crystal Display (LCD) displays use array of liquid crystal elements to create the image; a backlight creates the light, and the display uses the LCD elements to control how much light passes through tor each the viewer. LCD technology is cheap to manufacture and is relatively energy efficient, making it very popular in HDTVs and other display devices such as computer monitors and mobile phone displays.

The display passes an electrical signal to each liquid crystal on the LCD display that controls how much light can pass through it, thus controlling the brightness. Each liquid crystal elements can be individually controlled, and colour is produced by using filters on the individual liquid crystals. LCD televisions group three elements (for red, green and blue) together to form a single pixel. By moderating how much light is allowed through each of these three liquid crystals, any one of the pixels can produce any colour in the spectrum.

There are various negatives to LCD displays. One of the problems is that it takes a certain amount of time for each individual liquid crystal to change the amount of light that is let through. This can result in ghosting on the display as the crystals lag behind the image, especially in fast action sequences that change quickly. Another problem with LCDs is viewing angle. Each liquid crystal can be thought of as a small pipe that lets light through from the backlight. As the viewer moves off from right in front of the display, less light reaches them. Other technologies, like Plasma, create the light closer to the screen, with the result that the light exits the pipe at a wider angle than an LCD allows.

Another problem is burn-in. If a static image is left on an Liquid Crystal Display TV for an extended period of time, the individual liquid crystal elements may become fatigued and get stuck, ending up with a ghost of that image on the screen. This has become much less of an issue in recent years as manufacturers have used various techniques to address it, such as pixel orbiting. The other problem with LCD displays is the quality of black produced. As the backlight is always on with an LCD display, there will always be some light coming through. Other technologies like Plasma and rear projection displays are able to produce much deeper blacks. LCD TVs do have a higher maximum brightness than Plasma displays, however.

Despite these drawbacks, the inexpensive nature of Liquid Crystal Display technology makes it the single most popular display type for modern televisions.

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