Television set
A television set or television receiver, more commonly called a television, TV, TV set, telly, or tele, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasting through satellites or cables, or viewing and hearing a computer. Introduced in the late 1920s in mechanical form, television sets became a popular consumer product after World War II in electronic form, using cathode ray tube technology. The addition of color to broadcast television after 1953 further increased the popularity of television sets in the 1960s, and an outdoor antenna became a common feature of suburban homes. The ubiquitous television set became the display device for the first recorded media in the 1970s, such as Betamax, VHS and later DVD. It has been used as a display device since the first generation of home computers and dedicated video game consoles in the 1980s. By the early 2010s, flat-panel television incorporating liquid-crystal display technology, especially LED-backlit LCD technology, largely replaced CRT and other display technologies.
Modern flat panel TVs are typically capable of high-definition display and can also play content from a USB device.
History
Early television
s were commercially sold from 1928 to 1934 in the United Kingdom, United States, and Soviet Union. The earliest commercially made televisions were radios with the addition of a television device consisting of a neon tube behind a mechanically spinning disk with a spiral of apertures that produced a red postage-stamp size image, enlarged to twice that size by a magnifying glass. The Baird "Televisor" is considered the first mass-produced television, selling about a thousand units.In 1926, Kenjiro Takayanagi demonstrated the first TV system that employed a cathode ray tube display, at Hamamatsu Industrial High School in Japan. This was the first working example of a fully electronic television receiver. His research toward creating a production model was halted by the US after Japan lost World War II.
The first commercially made electronic televisions with cathode ray tubes were manufactured by Telefunken in Germany in 1934, followed by other makers in France, Britain, and America. The cheapest model with a 12-inch screen was $445. An estimated 19,000 electronic televisions were manufactured in Britain, and about 1,600 in Germany, before World War II. About 7,000–8,000 electronic sets were made in the U.S. before the War Production Board halted manufacture in April 1942, production resuming in August 1945. Television usage in the western world skyrocketed after World War II with the lifting of the manufacturing freeze, war-related technological advances, the drop in television prices caused by mass production, increased leisure time, and additional disposable income. While only 0.5% of U.S. households had a television in 1946, 55.7% had one in 1954, and 90% by 1962. In Britain, there were 15,000 television households in 1947, 1.4 million in 1952, and 15.1 million by 1968.
Transistorized television
Early electronic television sets were large and bulky, with analog circuits made of vacuum tubes. Following the invention of the first working transistor at Bell Labs, Sony founder Masaru Ibuka predicted in 1952 that the transition to electronic circuits made of transistors would lead to smaller and more portable television sets. The first fully transistorized, portable solid-state television set was the 8-inch Sony TV8-301, developed in 1959 and released in 1960. This began the transformation of television viewership from a communal viewing experience to a solitary viewing experience. By 1960, Sony had sold over 4million portable television sets worldwide.The MOSFET was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959, and presented in 1960. RCA Laboratories researchers W.M. Austin, J.A. Dean, D.M. Griswold and O.P. Hart in 1966 proposed the use of the MOSFET in television circuits, including RF amplifier, low-level video, chroma and AGC circuits. The MOSFET was later widely adopted for most television circuits.
By the late 1960s and early 1970s, color television had come into wide use. In Britain, BBC1, BBC2 and ITV were regularly broadcasting in colour by 1969.
LCD television
Building on the work of Mohamed M. Atalla and Dawon Kahng on the MOSFET, Paul K. Weimer at RCA developed the thin-film transistor in 1962. It was a type of MOSFET distinct from the standard bulk MOSFET. The idea of a TFT-based liquid-crystal display was conceived by Bernard Lechner of RCA Laboratories in 1968. Lechner, F. J. Marlowe, E. O. Nester and J. Tults demonstrated the concept in 1968 with a dynamic scattering LCD that used standard discrete MOSFETs.In 1973, T. Peter Brody, J. A. Asars and G. D. Dixon at Westinghouse Research Laboratories demonstrated the first thin-film-transistor liquid-crystal display. Brody and Fang-Chen Luo demonstrated the first flat active-matrix liquid-crystal display in 1974.
By 1982, pocket LCD TVs based on AM LCD technology were developed in Japan. The 2.1-inch Epson ET-10 was the first color LCD pocket TV, released in 1984. In 1988, a Sharp research team led by engineer T. Nagayasu demonstrated a 14-inch full-color LCD display, which convinced the electronics industry that LCD would eventually replace cathode-ray tube as the standard television display technology.
During the first decade of the 21st century, CRT "picture tube" display technology was almost entirely supplanted worldwide by flat-panel displays. By the early 2010s, LCD TVs, which increasingly used LED-backlit LCDs, accounted for the overwhelming majority of television sets being manufactured.
Display
Television sets may employ one of several available display technologies. As of mid-2019, LCDs overwhelmingly predominate in new merchandise, but OLED displays are claiming an increasing market share as they become more affordable and DLP technology continues to offer some advantages in projection systems. The production of plasma and CRT displays has been almost completely discontinued.There are four primary competing TV technologies:
- CRT
- LCD
- OLED
- Plasma
CRT
It has a means to accelerate and deflect the electron beam onto the screen to create the images. The images may represent electrical waveforms, pictures, radar targets or others. The CRT uses an evacuated glass envelope, which is large, deep, fairly heavy, and relatively fragile. As a matter of safety, both the face and back were typically made of thick lead glass so as to block most electron emissions from the electron gun in the very back of the tube. By the early 1970s, most color TVs replaced leaded glass in the face panel with vitrified barium glass, which also blocked electron gun emissions but allowed better color visibility. This also eliminated the need for cadmium phosphors in earlier color televisions. Leaded glass, which is less expensive, continued to be used in the funnel glass, which is not visible to the consumer.
In television sets and computer monitors, the entire front area of the tube is scanned repetitively and systematically in a fixed pattern called a raster. An image is produced by controlling the intensity of each of the three electron beams, one for each additive primary color with a video signal as a reference. In all modern CRT monitors and televisions, the beams are bent by magnetic deflection, a varying magnetic field generated by coils and driven by electronic circuits around the neck of the tube, although electrostatic deflection is commonly used in oscilloscopes, a type of diagnostic instrument.
DLP
Digital Light Processing is a type of projector technology that uses a digital micromirror device. Some DLPs have a TV tuner, which makes them a type of TV display. It was originally developed in 1987 by Larry Hornbeck of Texas Instruments. While the DLP imaging device was invented by Texas Instruments, the first DLP based projector was introduced by Digital Projection Ltd in 1997. Digital Projection and Texas Instruments were both awarded Emmy Awards in 1998 for the DLP projector technology. DLP is used in a variety of display applications from traditional static displays to interactive displays and also non-traditional embedded applications including medical, security, and industrial uses.DLP technology is used in DLP front projectors, DLP rear projection television sets, and digital signs. It is also used in about 85% of digital cinema projection, and in additive manufacturing as a power source in some printers to cure resins into solid 3D objects.
Plasma
A plasma display panel is a type of flat panel display common to large TV displays or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps.LCD
Liquid-crystal-display televisions are television sets that use Liquid-crystal displays to produce images. LCD televisions are much thinner and lighter than cathode ray tube of similar display size and are available in much larger sizes. When manufacturing costs fell, this combination of features made LCDs practical for television receivers.In 2007, LCD televisions surpassed sales of CRT-based televisions globally for the first time, and their sales figures relative to other technologies accelerated. LCD TVs quickly displaced the only major competitors in the large-screen market, the plasma display panel and rear-projection television. In the mid-2010s LCDs became, by far, the most widely produced and sold television display type.
LCDs also have disadvantages. Other technologies address these weaknesses, including OLEDs, FED and SED.
OLED
An OLED is a light-emitting diode 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. Generally, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens. It is also used for computer monitors, portable systems such as mobile phones, handheld game consoles and PDAs.There are two main families of OLED: those based on small molecules and those employing polymers. Adding mobile ions to an OLED creates a light-emitting electrochemical cell or LEC, which has a slightly different mode of operation. OLED displays can use either passive-matrix or active-matrix addressing schemes. Active-matrix OLEDs require a thin-film transistor backplane to switch each individual pixel on or off, but allow for higher resolution and larger display sizes.
An OLED display works without a backlight. Thus, it can display deep black levels and can be thinner and lighter than a liquid crystal display. In low ambient light conditions such as a dark room, an OLED screen can achieve a higher contrast ratio than an LCD, whether the LCD uses cold cathode fluorescent lamps or LED backlight.