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The Plasma display panel was invented at the University of Illinois at Urbana-Champaign by Donald L. Bitzer and H. Gene Slottow in 1964 for the PLATO Computer System. The original monochrome (usually orange or green) panels enjoyed a surge of popularity in the early 1970s because the displays were rugged and needed neither memory nor refresh circuitry. There followed a long period of sales decline in the late 1970s as semiconductor memory made CRT displays incredibly cheap. Nonetheless, plasma's relatively large screen size and thin profile made the displays attractive for high-profile placement such as lobbies and stock exchanges. In 1983, IBM introduced a 19" orange on black monochrome display (model 3290 'information panel') which was able to show four simultaneous 3270 virtual machine (VM) terminal sessions. In 1992, Fujitsu introduced the world's first 21-inch full color display. It was a hybrid based on the plasma display created at the University of Illinois at Urbana-Champaign and NHK STRL, achieving superior brightness. Passive-matrix and active-matrix (Patterned Vertical Alignment) is a more advanced version of MVA technology offered by Samsung. Developed independently, it suffers from the same problems as MVA, but boasts the best contrast ratios of any TFT technology. 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. The TN display suffers from limited viewing angles, especially in the vertical direction, and some are unable to display the full 16.7 million colors (24-bit truecolor) available from modern graphics cards. These particular panels, with 6 bits per color channel as opposed to 8, can approach true 24-bit color using a dither method which quickly cycles pixels to simulate a given shade, which are noticeable to some and discomforting to others. Overall, color reproduction and linearity on TN panels is poor. Shortcomings in display color gamut (often referred to as a percentage of the NTSC color gamut) can also be attributed to backlighting technology. It is not uncommon for displays with CCFL (Cold Cathode Fluorescent Lamps) based lighting to range from 40% to 76% of the NTSC color gamut, whereas displays utilizing white LED backlights may extend past 100% of the NTSC color gamut -a difference quite perceivable by the human eye.
Main article: Color LCD 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. 1904: Otto Lehmann publishes his major work "Liquid Crystals" MVA (Multi-domain Vertical Alignment) was originally developed in 1998 by Fujitsu as a compromise between TN and IPS. It achieved fast pixel response (at the time), wide viewing angles, and high contrast at the cost of brightness and color reproduction. * While CRTs are capable of displaying multiple video resolutions without introducing artifacts, LCD displays usually produce only crisp images in their "native resolution" or even fractions of it. A diagram of the Pixel layout
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The layout of the circuit is very similar to the one used in DRAM computer memory but rather than being built using silicon wafers, the whole structure needs to be created on glass. Many of the processing techniques used in creating circuits on silicon require temperatures in excess of the melting point of glass. The silicon substrate of normal semiconductors is grown from liquid silicon to produce a large single crystal with excellent properties for transistors. The silicon layer for TFT LCDs is deposited from Silane gas to produce an amorphic or polycrystalline silicon layer which is far less suitable for producing high grade transistors. Construction In-Plane Switching (IPS) LCD technology still has a few drawbacks in comparison to some other display technologies:
* LCD screens occasionally suffer from image persistence, which is similar to screen burn on CRT displays. Competing displays include the Cathode ray tube, OLED, AMLCD, DLP, SED-tv and field emission flat panel displays. The main advantage of plasma display technology is that a very wide screen can be produced using extremely thin materials. Since each pixel is lit individually, the image is very bright and looks good from almost every angle. Because many plasma displays still have a lower resolution the image quality is often not quite up to the standards of good LCD displays or cathode ray tube sets, but it certainly meets most people's expectations. Also, most cheaper consumer displays appear to have an insufficient color depth - a moving dithering pattern may be easily noticible for a discerning viewer over flat areas or smooth gradients; expensive high-res panels are much better at managing the problem. Analysts predicted that MVA would corner the mainstream market, but instead, TN has risen to dominance. A contributing factor was the higher cost of MVA, along with its slower pixel response (which rises dramatically for small changes in brightness). * The viewing angle of a LCD is usually less than that of most other display technologies thus reducing the number of people who can conveniently view the same image. However, this negative has actually been capitalised upon in two ways. Some vendors offer portables with intentionally reduced viewing angle, to provide additional privacy for example when using the PC in airplanes. Secondly, it allows multiple TV outputs from the same LCD screen just by changing the angle from where the TV is seen. Such a set can also show two different images to one viewer, providing 3-D. Before applying an electrical charge, the liquid crystal molecules are in a relaxed state. Charges on the molecules cause these molecules to align themselves in a helical structure, or twist (the "crystal"). In some LCDs, the electrode may have a chemical surface that seeds the crystal, so it crystallizes at the needed angle. Light passing through one filter is rotated as it passes through the liquid crystal, allowing it to pass through the second polarized filter. A small amount of light is absorbed by the polarizing filters, but otherwise the entire assembly is transparent.