Flat panel display
|This article needs additional citations for verification. (November 2009)|
Flat panel displays, commonly known as flat screen TVs, encompass a growing number of electronic visual display technologies. They are far lighter and thinner than traditional television sets and video displays that use cathode ray tubes (CRTs), and are usually less than 10 centimetres (3.9 in) thick.
Flat panel displays can be divided into two general display technology categories: volatile and static.
In many applications, specifically modern portable devices such as laptops, mobile phones, digital cameras, camcorders, point-and-shoot cameras, and pocket video cameras, any display disadvantages are made up for by portability advantages.
Most of the modern flat-panel displays use LCD technologies. Most LCD screens are back-lit to make them easier to read in bright environments. They are thin and light. They provide better linearity and higher resolution.
A multifunctional monitor (MFM) is a flat panel display that has additional video inputs (more than a typical LCD monitor) and is designed to be used with a variety of external video sources. In many instances, an MFM also includes a TV tuner, making it similar to a LCD TV that offers computer connectivity.
The first engineering proposal for a flat panel TV was by General Electric as a result of its work on radar monitors. Their publication of their findings gave all the basics of future flat panel TVs and monitors. But GE did not continue with the R&D required and never built a working flat panel at that time.
The first production flat panel display was the Aiken tube, developed in the early 1950s and produced in limited numbers in 1958. This saw some use in military systems as a heads up display, but conventional technologies overtook its development. Attempts to commercialize the system for home television use ran into continued problems and the system was never released commercially. The Philco Predicta featured a relatively flat (for its day) cathode ray tube setup and would be the first commercially released "flat panel" upon its launch in 1958; the Predicta was a commercial failure.
Liquid crystal displays
Liquid crystal displays are lightweight, compact, portable, cheap, more reliable, and easier on the eyes than CRTs. A thin layer of liquid crystal, a liquid that exhibits crystalline properties, is sandwiched between two electrically conducting plates.The top plate has transparent electrodes deposited on it, and the back plate is a mirror. By applying proper electrical signals across the plates, various segments of the liquid crystal can be activated, causing changes in their light diffusing or polarizing properties. These segments can either transmit or block light. An image is produced by passing light through selected segments of the liquid crystal and then reflected it back from the mirror to the viewer. They are used in various electronics like watches, calculators, and notebook computers.
Liquid crystal displays with Light-emitting diodes (LED) A light-emitting diode (LED) display is a two-lead semiconductor light source that resembles a basic pn-junction diode, except that an LED also emits light. This form of LCD( liquid crystal) display is the most prevalent in use today. This form of LCD display is still a Liquid Crystal Display that uses a LED ( light emitting diode) backlight. It is not a separate technology from a LCD display.
A plasma display consists of two glass plates separated by a thin gap filled with a gas such as neon. Each of these plates has several parallel electrodes running across it. The electrodes on the two plates are at right angles to each other. A voltage applied between the two electrodes one on each plate causes a small segment of gas at the two electrodes to glow. The glow of gas segments is maintained by a lower voltage that is continuously applied to all electrodes.
In an electroluminescent display (ELD), the image is created by applying electrical signals to the plates which makes the phosphor glow.
Organic light-emitting diode
An OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound which emits light in response to an electric current. This layer of organic semiconductor is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, portable systems such as mobile phones, handheld game consoles and PDAs. A major area of research is the development of white OLED devices for use in solid-state lighting applications.
Volatile displays require that pixels be periodically refreshed to retain their state, even for a static image. This refresh typically occurs many times a second. If this is not done, the pixels will gradually lose their coherent state, and the image will "fade" from the screen.
Examples of volatile flat panel displays
- Active-matrix liquid-crystal display (AMLCD)
- Electronic paper: E Ink, Gyricon
- Electroluminescent display (ELD)
- Digital Light Processing (DLP)
- Field emission display (FED), also named nano-emissive display (NED)
- Interferometric modulator display (IMOD)
- Light-emitting diode display (LED)
- Liquid-crystal display (LCD)
- Organic light-emitting diode (OLED)
- Plasma display panel (PDP)
- Quantum dot display (QLED)
- Surface-conduction electron-emitter display (SED, SED-TV)
Only a few of these displays are commercially available today, though OLED displays are beginning deployment only in small sizes, mainly in cellular telephones.
Static flat panel displays rely on materials whose color states are bistable. This means that the image they hold requires no energy to maintain, but instead requires energy to change. This results in a much more energy-efficient display, but with a tendency towards slow refresh rates which are undesirable in an interactive display.
Bistable flat panel displays are beginning deployment in limited applications (Cholesteric displays, manufactured by Magink, in outdoor advertising; electrophoretic displays in e-book products from Sony and iRex; anlabels).
- Computer monitor
- Electronic paper
- Flexible display
- Large-screen television technology
- LED-backlit LCD television
- Display motion blur
- Mobile display
- Sony Watchman
- Stereoscopy 3D displays requiring no special glasses
- Touch panel
- Transparent display
- "Proposed Television Sets Would Feature Thin Screens." Popular Mechanics, November 1954, p. 111.
- William Ross Aiken, "History of the Kaiser-Aiken, thin cathode ray tube", IEEE Transactions on Electron Devices, Volume 31 Issue 11 (November 1984), pp. 1605-1608.
- Plasma TV Science.org - The History of Plasma Display Panels
- Castellano, Joseph A. (2005). Liquid gold: the story of liquid crystal displays and the creation of an industry ([Online-Ausg.] ed.). New Jersey [u.a.]: World Scientific. p. 176. ISBN 981-238-956-3.
|Wikimedia Commons has media related to Plasma displays.|
|Wikimedia Commons has media related to LCD computer monitors.|
|Wikimedia Commons has media related to LCD TVs.|