Television set

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"TV set" redirects here. For other uses, see Television set (disambiguation).
A modern flat panel television set

A television set, also called a television receiver, television, TV set, TV, or "telly" (UK), is a device that combines a tuner, display, and speakers for the purpose of viewing television. Television sets became a popular consumer product after World War II, using vacuum tubes and cathode ray tube displays. The addition of color to broadcast television after 1953 further increased the popularity of television sets, 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 and 1980s, such as videotape and laserdisc movies. 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 2014, flat panel television sets incorporate liquid-crystal, plasma, or LED flat-screen displays, solid-state circuits, microprocessor controls and can interface with a variety of video signal sources, allowing the user to view broadcast and subscription cable TV signals or satellite television, recorded material on DVD or Blu-ray discs, or home security systems, and over-the-air broadcasts received through an indoor or outdoor antenna. Modern flat panel TVs are typically capable of high-definition display (720p or 1080p).

History[edit]

Main article: History of television
British Murphy black and white 405-line Television receiver 1951.

Mechanical televisions were commercially sold from 1928 to 1934 in the United Kingdom,[1] United States, and Soviet Union.[2] The earliest commercially made televisions sold by Baird in the UK in 1928 were radios with the addition of a television device consisting of a neon tube behind a mechanically spinning disk (patented by German engineer Paul Nipkow in 1884, see Nipkow 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" was also available without the radio. The Televisor sold in 1930–1933 is considered the first mass-produced television, selling about a thousand units.[3]

The first commerciallly made electronic televisions with cathode ray tubes were manufactured by Telefunken in Germany in 1934,[4][5] followed by other makers in France (1936),[6] Britain (1936),[7] and America (1938).[8][9] The cheapest of the pre–World War II factory-made American sets, a 1938 image-only model with a 3-inch (8 cm) screen, cost US$125 (equivalent to $2,094 in 2014). The cheapest model with a 12-inch (30 cm) screen was $445 (equivalent to $7,456 in 2014).[10]

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.[11] before the War Production Board halted manufacture in April 1942, production resuming in August 1945.

Television usage in the United States skyrocketed after World War II with the lifting of the manufacturing freeze, war-related technological advances, the gradual expansion of the television networks westward, 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.[12] In Britain, there were 15,000 television households in 1947, 1.4 million in 1952, and 15.1 million by 1968.[citation needed]

This video shows the operation of a typical CRT television of the early 1990s.

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. [13]

By the later 2000s, CRT display technology was largely supplanted in the home electronics market by flat panel displays such as LCD and plasma.

Components[edit]

Modern televisions consist of a display, antenna or radio frequency (RF) input (a TV aerial plug or an F connector), and a tuner. The existence of a television tuner (nowadays, a digital television tuner) in a display device distinguishes it from a video monitor—which receives signals that are already processed. Additionally TVs almost always include amplified speakers and teletext. Some TVs have had subwoofers installed in the set. Most modern TVs also feature additional inputs for devices such as DVD players, video game consoles, and headphones; the most common types for analog audio and analog video are RCA (for composite video and component video), mini-DIN for S-Video, SCART and D-terminal can be found in Europe and Japan respectively, the newer HDMI port, which is used with high definition video sources such as the Blu-ray. HDMI can also connect to computers. Other inputs may include USB and Bluetooth. Some high-end TVs have Ethernet ports to receive information from the Internet, like stocks, weather, or news. Most TVs made since the early 1980s also feature an infra-red sensor to detect the signals sent by remote controls.

Display technologies[edit]

Televisions in the 2000s use various display technologies such as CRT (this is becoming very uncommon), LCD, Plasma, Digital Light Processing (DLP), and more recently OLED. LCD, plasma, and OLED TVs are much lighter and thinner than a CRT TV of the same size. Consequently, flat screen TVs are available with much larger screens (e.g., 50, 60, 70 or even 100 inches, measured diagonally, while the largest CRT TVs were about 34 inches). Some front projectors, which feature TV tuners, can also be considered as televisions.

CRT[edit]

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. [14]

Cutaway rendering of a color CRT:
1. Three Electron guns (for red, green, and blue phosphor dots)
2. Electron beams
3. Focusing coils
4. Deflection coils
5. Anode connection
6. Mask for separating beams for red, green, and blue part of displayed image
7. Phosphor layer with red, green, and blue zones
8. Close-up of the phosphor-coated inner side of the screen

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.[15] 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.[15]

A 14 inch cathode ray tube showing its deflection coils and electron guns
Typical 1950s United States television set
A flat CRT assembly inside a vintage 1984 Sinclair FTV1 pocket TV
Electron gun

Larger CRT televisions, particularly those used in family sitting rooms in the 1980s, have been referred to as "Live Aid TVs", given that the two billion people who watched the 1985 event would have in most cases used CRT sets to do so.[16]

LCD TVs[edit]

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., 50 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,[citation needed] and their sales figures relative to other technologies are accelerating. LCD TVs are quickly displacing the only major competitors in the large-screen market, the plasma display panel and rear-projection television. LCDs are, by far, the most widely produced and sold television display type.

LCDs also have a variety of disadvantages. Other technologies address these weaknesses, including organic light-emitting diodes (OLED), FED and SED, but as of 2012 none of these have entered widespread production.

Plasma TVs[edit]

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.

DLP[edit]

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. [17]

OLED[edit]

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[edit]

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. 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 CD, DVD players and PVRs for greater functionality.[citation needed]

Recycling and disposal[edit]

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.[18] Challenges with recycling television sets include proper HAZMAT disposal, landfill pollution, and illegal international trade.[19]

See also[edit]

References[edit]

  1. ^ Early British Television: Baird, Television History: The First 75 Years.
  2. ^ Pre-1935, Television History: The First 75 Years. The French model shown does not appear to have entered production.
  3. ^ Pre-1935 Baird Sets: UK, Television History: The First 75 Years.
  4. ^ Telefunken, Early Electronic TV Gallery, Early Television Foundation.
  5. ^ 1934–35 Telefunken, Television History: The First 75 Years.
  6. ^ 1936 French Television, Television History: The First 75 Years.
  7. ^ 1936 Baird T5, Television History: The First 75 Years.
  8. ^ Communicating Systems, Inc., Early Electronic TV Gallery, Early Television Foundation.
  9. ^ America's First Electronic Television Set, Television History: The First 75 Years.
  10. ^ American TV Prices, Television History: The First 75 Years.
  11. ^ Annual Television Sales in USA, Television History: The First 75 Years.
  12. ^ Number of TV Households in America, Television History: The First 75 Years.
  13. ^ http://www.dailymail.co.uk/news/article-1328760/Britains-oldest-colour-TV-going-strong-42-years-on.html
  14. ^ "History of the Cathode Ray Tube". About.com. Retrieved 4 October 2009. 
  15. ^ a b "'How Computer Monitors Work'". Retrieved 4 October 2009. 
  16. ^ Raine, Adrian. "21st Century Television's Faltering Moral Compass". The Economist. 8 April 2009.
  17. ^ "How Digital Light Processing Works". THRE3D.com. Retrieved 3 February 2014. 
  18. ^ How To Scrap A Television, www.ScrapMetalJunkie.com
  19. ^ CRT disposal, www.Bordercenter.org

External links[edit]