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1904: Otto Lehmann publishes his major work "Liquid Crystals" IPS (In-Plane Switching) was developed by Hitachi in 1996 to improve on the poor viewing angles and color reproduction of TN panels. These improvements came at a loss of response time, which was initially on the order of 50ms. IPS panels were also extremely expensive. 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. Plasma displays are bright (1000 lx or higher for the module), have a wide color gamut, and can be produced in fairly large sizes, up to 260 cm (102 inches) diagonally. They have a very high "dark-room" contrast, creating the "perfect black" desirable for watching movies. The display panel is only 6 cm (2 1/2 inches) thick, while the total thickness, including electronics, is less than 10 cm (4 inches). Plasma displays use as much power per square meter as a CRT or an AMLCD television; in 2004 the cost has come down to US$1900 or less for the popular 42 inch (107 cm) diagonal size, making it very attractive for home-theatre use. Real life measurements of plasma power consumption find it to be much less than that normally quoted by manufacturers. Nominal measuments indicate 150 Watts for a 50" screen. The lifetime of the latest generation of PDPs is estimated at 60,000 hours to half life when displaying video. Half life is the point where the picture has degraded to half of its original brightness, which is considered the end of the functional life of the display. So if you use it at an average of 2-1/2 hours a day, the PDP will last approximately 65 years.
In 1969, the twisted nematic field effect in liquid crystals was discovered by James Fergason at Kent State University in the USA, and in 1971 his company ILIXCO (now LXD Incorporated) produced the first LCDs based on it, which soon superseded the poor-quality DSM types. A general purpose alphanumeric LCD, with two lines of 16 characters.
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During the 1970s and early 1980s, LCD technology was not yet mature. However, during the early 80's timeframe, a tabletop video game called Popeye was made with a color LCD, a device with technology ahead of it's time. Technologies used for portable devices made prior to the 1990s to use color graphics include tabletop video games that use Vacuum fluorescent displays and also, before modern laptop computers that used color graphics, the so-called luggable computer, Commodore SX-64 used color graphics on a mini-CRT. The Commodore SX-64 was however bulky hence the aforementioned term luggable. Important factors to consider when evaluating an LCD monitor include resolution, viewable size, response time (sync rate), matrix type (passive or active), viewing angle, color support, brightness and contrast ratio, aspect ratio, and input ports (e.g. DVI or VGA). LCD technology still has a few drawbacks in comparison to some other display technologies: Twisted Nematic displays contain liquid crystal elements which twist and untwist at varying degrees to allow light to pass through. When no voltage is applied to a TN liquid crystal cell, the light is polarized to pass through the cell. In proportion to the voltage applied, the LC cells twist up to 90 degrees changing the polarization and blocking the light's path. By properly adjusting the level of the voltage most any grey level or transmission can be achieved. LCD panels are more likely to have defects than most ICs due to their larger size. In this example, a 12" SVGA LCD has 8 defects and a 6" wafer has only 3 defects. However, 134 of the 137 dies on the wafer will be acceptable, whereas rejection of the LCD panel would be a 0% yield. The standard is much higher now due to fierce competition between manufacturers and improved quality control. An SVGA LCD panel with 4 defective pixels is usually considered defective and customers can request an exchange for a new one. The location of defective pixels is also important. A display with only a few defective pixels may be unacceptable if the defective pixels are near each other. Manufacturers may also relax their replacement criteria when defective pixels are in the center of the viewing area.
1936: The Marconi Wireless Telegraph company patents the first practical application of the technology, "The Liquid Crystal Light valve". The molecules of the liquid crystal have electric charges on them. By applying small electrical charges to transparent electrodes over each pixel or subpixel, the molecules are twisted by electrostatic forces. This changes the twist of the light passing through the molecules, and allows varying degrees of light to pass (or not to pass) through the polarizing filters. 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.