los televisores

A television is an electronic facility for receiving and reproducing television signals. Usually consists of a display and controls or controls. The word comes from the Greek tele (τῆλε; away) and Latin viewfinder (agent videre 'see'). It was created on January 26, 1926 by John Logie Baird.
Its operation is based on the phenomenon of photoelectricity, which is responsible for converting light into electricity in a camera that can transmit high frequency waves to the receiving antennas and is reproduced on the screen of our television . The TV is one of the most everyday appliances.

-Elements of a television

Screen Thanks to advances in display technology, there are now several classes in modern TVs:
Cathode ray tube or CRT: The most common displays are direct-view tubes are achieved with up to 37 inches diagonal. Until 2007, are still the least expensive, and it is a mature technology that can deliver a great picture. Since we do not have a fixed resolution, although a minimum resolution, given the separation between points, can display fonts in various resolutions with the best possible image quality. The frame rate of NTSC TV is 29.97 Hz and 25 Hz in the case of the PAL standard TVs. Visible vertical resolution of the TV is 480 lines NTSC, PAL and the 575-lines. Cathode ray tubes were quite bulky and heavy, are currently being replaced by formats Plasma, LCD and more recently LED. Projection: They are large-screen TVs up to 100 diagonal inches or more. Uses three types of projection systems: CRT, LCD and DLP (chip micromirror device). Rear-projection TVs have existed since the 70's, but at that time had no common definition of a television cathode ray. Current models are much improved, and offer a large price. Projection screens do not give good results in the light of day or in brightly lit rooms, making them more suitable for darkened areas. Liquid crystal display and plasma: The current developments allow the manufacture of flat panel TVs using liquid crystal technology for active matrix (LCD) or plasma. They are ready for high definition (1920x1080) pixels, although some have less resolution. These televisions can have only a couple of inches wide, and can be hung on a wall like a painting or be put on base. Some models can also be used as computer monitors. LCD flat screens can have narrow viewing angles, and are less suitable for the home, although this is being addressed in most current computers. LED Matrix has become one of the options for video outdoors and in stadiums, since the advent of light emitting diodes and their respective circuits ultraluminous. The LED displays allow you to create scalable ultragrandes currently existing technologies that can not igualar.Recientemente has taken the initiative to apply this technology to the domestic TV. They take on different characteristics to other types of display. Lower power consumption compared to LCD screens, improved durability, reduced thickness of the same and higher contrast are examples of these features. The pioneer in this field was Korea's Samsung commercial. [Edit] Resolution Resolution in pixels is the number of individual dots called pixels in a given screen. A typical resolution of 720x480 means that the TV has 720 horizontal pixels and 480 pixels on the vertical axis, the resolution affects the sharpness of the image, higher resolution screen, the greater its clarity. The first resolution had 48 lines and each of the factories used different systems. The standardization of these systems began in July 1941 when he won the NTSC system, valid for all states of the United States, 325 lines. Europe achieved a 625 line at the end of the war, France had a proper 819 lines and England maintained their 405-line. Subsequently the NTSC system was improved.
[Edit] Controls Contrast ratio is a measure of the interval between light and dark points of the screen. The higher the contrast the better the image looks in their richness, depth and shadow detail. The contrast control of a television actually controls the image intensity or brightness [1]. The brightness of an image measures the overall brightness of the screen. It is measured in cd / m2 equivalent to the amount of candles required to form the image. The brightness control shifts the "black point" or shadow level, affecting the contrast ratio or gamma of the image [1]. During the years immediately following World War II experiments were conducted with several different television systems in some European countries, including France and the Netherlands, but it was the USSR, which began regular broadcasts in Moscow in 1948, the first country in the operate in the public service. About 98% of households in the USSR (3.2 people per recipient) and France (2.5) has TV, the percentage of 94 in Italy (3.9) and 93 households now part of Germany the reunified Federal Republic of Germany (2.7).

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 Television in space
  NASA Logo TV.Las television cameras aboard U.S. spacecraft transmitted to Earth until spatial information inaccessible. The Mariner spacecraft, launched by the United States between 1965 and 1972, sent thousands of images of Mars. The Ranger and Surveyor series broadcast thousands of photographs of the lunar surface for scientific analysis and preparation before the manned Moon landing in July 1969, while millions of people around the world could watch the broadcast in color directly from the lunar surface.
Since 1960 have also been used extensively in television cameras orbiting meteorological satellites. Vidicon cameras recorded images prepared land of clouds and weather conditions during the day, while infrared cameras capture images at night. The images sent by satellites not only as useful to predict the weather but to understand the global weather systems. We used high-resolution vidicon cameras aboard satellites for Earth Resources Technology also known as ERTS to study crops as well as minerals and marine resources.

 

material bajado de la pagina:http://es.wikipedia.org/wiki/Televisor

 

plasma TV
A "plasma" as these devices are commonly known, is a flat screen where the image is created by electric shocks applied to gases such as neon and xeon. These gases glow or light up when exposed to an electric field, and the image of a plasma TV is made up of hundreds of thousands of small tubes containing these same gases. Each of these tubes, controlled by a computer to form the image corresponds to a pixel or point in a composite image. The image is reconstructed hundreds of times per second these computers, according to the signal received, either from TV or video.
The story begins plasma TV's curiosity in the sixties (it is common to think that is an invention of art), particularly in 1964 at the University of Illinois. Its inventor was Donald Bitzer, who invented this device to a computer system called PLATO, the first screens of this type were of course monochrome, typically orange or green characters. Were used in the 70's, but then other screens began to replace the plasma in the market by being cheaper due to advances in semiconductor technology. In 1992, Fujitsu introduced the first color plasma display in a format of 21 inches, and in 1997 Pioneer launches the general public the first plasma TV as we know them today, used to play back TV high definition (HDTV). Brands like Sony, Samsung, Panasonic and LG are competing strongly with their latest models on the market today.
Until recently, this TV format by far surpassed in functionality to LCD TVs, but improvements in this latest technology (improved viewing angle and color consistency), have almost equate this competition, and an estimated for convenience of use, lower cost and greater flexibility to repair the LCD may eventually be to the fore in the near future.
Over time, the image on the plasma TV is losing brightness and definition, and for this reason that manufacturers specify the hours of each screen (it is estimated that the first 2000 hours are the best performers, although the duration total art displays is 60,000 hours approx.) In addition, it requires great care, because if the screen breaks, repair is extremely complex (imagine thousands of tiny tubes to repair), and sometimes impossible.
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