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Color displays The TN+Film (Twisted Nematic) display is the most common consumer display type, due to its lower price. The pixel response time on modern TN panels is sufficiently fast to avoid the shadow-trail artifacts that were a cause for complaint in the past. This fast response time has been a heavily marketed aspect of TN displays, although in most cases this number does not reflect performance across the entire range of possible color transitions. However this marketing strategy, combined with the relatively lower cost of production for TN panels, has led to the dominance of TN in the consumer market. Enlarge To save cost in the electronics, LCDs are often multiplexed. In a multiplexed display, electrodes on one side of the display are grouped and wired together, and each group gets its own voltage source. On the other side, the electrodes are also grouped, with each group getting a voltage sink. The groups are designed so each pixel has a unique, unshared combination of source and sink. The electronics, or the software driving the electronics then turns on sinks in sequence, and drives sources for the pixels of each sink.
In-Plane Switching (IPS) In-plane switching is an LCD technology which aligns the liquid crystal cells in a horizontal direction. In this method, the electrical field is applied through each end of the crystal, but this requires the need for two transistors for each pixel instead of the one needed for a standard thin-film transistor (TFT) display. This results in blocking more transmission area requiring brighter backlights, which consume more power making this type of display undesirable for notebook computers. LCDs can be either transmissive or reflective, depending on the location of the light source. A transmissive LCD is illuminated from the back by a backlight and viewed from the opposite side (front). This type of LCD is used in applications requiring high luminance levels such as computer displays, televisions, personal digital assistants, and mobile phones. The illumination device used to illuminate the LCD in such a product usually consumes much more power than the LCD itself. A plasma display is an emissive flat panel display where light is created by phosphors excited by a plasma discharge between two flat panels of glass. The gas discharge contains no mercury (contrary to the backlights of an AMLCD); a mixture of noble gases (neon and xenon) is used instead. This gas mixture is inert and entirely harmless. Vertical Alignment displays are a form of LC displays in which the liquid crystal material naturally exists in a horizontal state removing the need for extra transistors (as in IPS). When no voltage is applied the liquid crystal cell, it remains perpendicular to the substrate creating a black display. When voltage is applied, the liquid crystal cells shift to a horizontal position, parallel to the substrate, allowing light to pass through and create a white display. VA liquid crystal displays provide some of the same advantages as IPS panels, particularly an improved viewing angle and improved black level. In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters. Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel. Older CRT monitors employ a similar method for displaying color. Color components may be arrayed in various pixel geometries, depending on the monitor's usage.
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Vertical Alignment (VA) Kent Displays, [1], has also developed a "no power" display that uses Polymer Stabilized Cholesteric Liquid Crystals(ChLCD). The major drawback to the ChLCD display is slow refresh rate, especially with low temperatures. MVA Normal Liquid Crystal Displays like those found in calculators have direct driven image elements – a voltage can be applied across one segment without interfering with other segments of the display. This is impractical for a large display with a large number of pixels since it would require millions of connections - top and bottom connections for each of red, green and blue of every pixel. To avoid this issue, the pixels are addressed in rows and columns which reduce the connection count from millions to thousands. If all the pixels in one row are driven with a positive voltage and all the pixels in one column are driven with a negative voltage, then the pixel at the intersection has the largest applied voltage and is switched. The problem with this solution is that all the pixels in the same column see a fraction of the applied voltage as do all the pixels in the same row, so although they are not switched completely, they do tend to darken. The solution to the problem is to supply each pixel with its own transistor switch which allows each pixel to be individually controlled. The low leakage current of the transistor also means that the voltage applied to the pixel does not leak away between refreshes to the display image. Each pixel is a small capacitor with a transparent ITO layer at the front, a transparent layer at the back and a layer of insulating liquid crystal between. TFT LCDs are a variant of liquid crystal display which use thin-film transistor technology to improve their image quality. TFT LCDs are one type of active matrix LCD, though this is usually synonymous with them. They are used in both flat panel displays and projectors. In computing, TFT monitors are rapidly displacing competing CRT technology, and are commonly available in sizes from 30 to 77 cm (~12 to 30 inches). As of 2005, they have also made inroads on the television market. In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters. Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel. Older CRT monitors employ a similar method for displaying color. Color components may be arrayed in various pixel geometries, depending on the monitor's usage. MVA * LCD screens occasionally suffer from image persistence, which is similar to screen burn on CRT displays. Zero-power displays
A general purpose alphanumeric LCD, with two lines of 16 characters. Brief history A French company, Nemoptic, has developed another zero-power, paper-like LCD technology which has been mass-produced in Taiwan since July 2003. This technology is intended for use in low-power mobile applications such as e-books and wearable computers. Zero-power LCDs are in competition with electronic paper. * Thin-film transistors and color filters