Television set

A television set, also called a television receiver, television, TV set, TV, or telly, is a device that combines a tuner, display, and loudspeakers for the purpose of viewing television. 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 tubes. 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 VHS and later DVD. It was also the display device for the first generation of home computers (e.g., Timex Sinclair 1000) and video game consoles (e.g., Atari) in the 1980s. In the 2010s flat panel television incorporating liquid-crystal displays, especially LED-backlit LCD displays, largely replaced cathode ray tubes and other displays.^{[1][2] [3] [4] [5]} Modern flat panel TVs are typically capable of high-definition display (720p, 1080i, 1080p) and can also play content from a USB device.

History

RCA 630-TS, the first mass-produced electronic television set, which sold in 1946–1947

Mechanical televisions were commercially sold from 1928 to 1934 in the United Kingdom,^[6] United States, and Soviet Union.^[7] 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" (sold in 1930–1933 in the UK) is considered the first mass-produced television, selling about a thousand units.^[8]

The first commercially made electronic televisions with cathode ray tubes were manufactured by Telefunken in Germany in 1934,^[9][10] followed by other makers in France (1936),^[11] Britain (1936),^[12] and America (1938).^[13][14] The cheapest model with a 12-inch (30 cm) screen was $445 (equivalent to $7,481 in 2016).^[15] 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.^[16] 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.^[17] In Britain, there were 15,000 television households in 1947, 1.4 million in 1952, and 15.1 million by 1968. 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.^[18]

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 LCD displays, accounted for the overwhelming majority of television sets being manufactured.^{[1][2] [3] [4] [5]}

Display

Television sets may employ one of several available display technologies. As of the mid-2010s, LCD displays 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.^{[1][2][3][19][4][5]}

CRT

A 14-inch cathode ray tube showing its deflection coils and electron guns

The cathode ray tube (CRT) is a vacuum tube containing one or more electron guns (a source of electrons or electron emitter) and a fluorescent screen used to view images.^[20] It has a means to accelerate and deflect the electron beam(s) onto the screen to create the images. The images may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets or others. The CRT uses an evacuated glass envelope which is large, deep (i.e. long from front screen face to rear end), fairly heavy, and relatively fragile. As a matter of safety, the face is typically made of thick lead glass so as to be highly shatter-resistant and to block most X-ray emissions, particularly if the CRT is used in a consumer product.

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 (red, green, and blue) with a video signal as a reference.^[21] 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.^[21]

DLP

The Christie Mirage 5000, a 2001 DLP projector.

Digital Light Processing (DLP) 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 Dr. 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 (standalone projection units for classrooms and business primarily), 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.^[22]

Plasma

A 103" diagonal plasma display panel by Panasonic

A plasma display panel (PDP) is a type of flat panel display common to large TV displays 30 inches (76 cm) 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

A generic LCD TV, with speakers on either side of the screen.

Liquid-crystal-display televisions (LCD TV) are television sets that use LCD display technology to produce images. LCD televisions are much thinner and lighter than cathode ray tube (CRTs) of similar display size, and are available in much larger sizes (e.g., 90 inch diagonal). When manufacturing costs fell, this combination of features made LCDs practical for television receivers.

In 2007, LCD televisions surpassed sales of CRT-based televisions worldwide 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.^[1][2]

LCDs also have disadvantages. Other technologies address these weaknesses, including OLEDs, FED and SED, but as of 2014 none of these have entered widespread production.

OLED

OLED TV

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. 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 games 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 (PMOLED) or active-matrix addressing schemes. Active-matrix OLEDs (AMOLED) 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 (LCD). 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.

Outdoor television

An outdoor television set designed for outdoor use is usually found in the outdoor sections of bars, sports fields, or other community facilities. Most outdoor televisions use High-definition television technology. Their body is more robust. The screens are designed to remain clearly visible even in sunny outdoor lighting. The screens also have anti-reflective coatings to prevent glare. They are weather-resistant and often also have anti-theft brackets. Outdoor TV models can also be connected with BD players and PVRs for greater functionality.^[23]

Recycling and disposal

Due to recent changes in electronic waste legislation, economical and environmentally friendly television disposal has been made increasingly more available in the form of television recycling. The salvage value of the materials of the set, such as copper wiring in CRT sets, offset the costs of recycling, and sometimes even positive gains.^[24] Challenges with recycling television sets include proper HAZMAT disposal, landfill pollution, and illegal international trade.^[25]

See also

• 3D television
• Active antenna
• Color killer
• Color television
• Digital video recorder
• DTV transition in the United States
• HDTV
• Home theater
• Multiplier
• Smart TV
• TV aerial plug
• Viera Cast

References

External links

Wikimedia Commons has media related to Television sets.