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Mechanical Television
Mechanical television or mechanical scan television is an obsolete television system that relies on a mechanism (engineering), mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror drum, to scan the scene and generate the video signal, and a similar mechanical device at the receiver to display the picture. This contrasts with vacuum tube electronic television technology, using electron beam scanning methods, for example in cathode-ray tube (CRT) televisions. Subsequently, modern solid-state liquid-crystal displays (LCD) and LED displays are now used to create and display television pictures. Mechanical scanning methods were used in the earliest experimental television systems in the 1920s and 1930s. One of the first experimental wireless television transmissions was by Scottish inventor John Logie Baird on October 2, 1925, in London. By 1928 many radio stations were broadcasting experimental television programs using mechanical systems. Howeve ...
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Television Set
A television set or television receiver (more commonly called TV, TV set, television, telly, or tele) is an electronic device for viewing and hearing television broadcasts, or as a computer monitor. It combines a tuner, display, and loudspeakers. 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 (CRT) 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 for consumer use in the 1970s, such as Betamax, VHS; these were later succeeded by DVD. It has been used as a display device since the first generation of home computers (e.g. Timex Sinclair 1000) and dedicated video game consoles (e.g., Atari) in the 1980s. By the early 2010s, flat-pane ...
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Photoconductivity
Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation. When light is absorbed by a material such as a semiconductor, the number of free electrons and holes increases, resulting in increased electrical conductivity. To cause excitation, the light that strikes the semiconductor must have enough energy to raise electrons across the band gap, or to excite the impurities within the band gap. When a bias voltage and a load resistor are used in series with the semiconductor, a voltage drop across the load resistors can be measured when the change in electrical conductivity of the material varies the current through the circuit. Classic examples of photoconductive materials include: * photographic film: Kodachrome, Fujifilm, Agfachrome, Ilford, ''etc.'', based on silver sulfide and silver bromi ...
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Constantin Perskyi
Constantin Dmitrievich Perskyi (Константин Дмитриевич Перский) (2 June 18545 April 1906) was a Russian scientist who is credited with coining the word television (''télévision'') in a paper that he presented in French at the 1st International Congress of Electricity, which ran from 18 to 25 August 1900 during the International World Fair in Paris. At the time, he was Professor of Electricity at the Artillery Academy of Saint Petersburg. His paper referred to the work of other experimenters in the field, including Paul Gottlieb Nipkow and Porfiry Ivanovich Bakhmetiev, who were attempting to use the photoelectric properties of selenium as the basis for their research in the field of image transmission. Biography Konstantin Perskyi was born on 2 June (21 May according to the Julian calendar), 1854 in Tver Governorate. He belonged to a noble family founded by a person who had moved out of Persia in the service of the grand prince of Dmitry Donskoy. He ...
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The Washington Star
''The Washington Star'', previously known as the ''Washington Star-News'' and the ''Washington'' ''Evening Star'', was a daily afternoon newspaper published in Washington, D.C., between 1852 and 1981. The Sunday edition was known as the ''Sunday Star''. The paper was renamed several times before becoming ''Washington Star'' by the late 1970s. For most of the time it was publishing, ''The Washington Star'' was the city's newspaper of record. It provided a longtime home to columnist Mary McGrory (1918-2004) and to cartoonist Clifford K. Berryman (1869-1949). On August 7, 1981, after 128 years, ''The Washington Star'' ceased publication and filed for bankruptcy. In the bankruptcy sale, ''The Washington Post'' purchased the land and buildings owned by ''The Washington Star'', including its printing-presses. History 19th century ''The Washington Star'' was founded on December 16, 1852, by Captain Joseph Borrows Tate. It was originally headquartered on "Newspaper Row" on Pennsyl ...
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Kerr Effect
The Kerr effect, also called the quadratic electro-optic (QEO) effect, is a change in the refractive index of a material in response to an applied electric field. The Kerr effect is distinct from the Pockels effect in that the induced index change for the Kerr effect is directly proportional to the ''square'' of the electric field instead of varying linearly with it. All materials show a Kerr effect, but certain liquids display it more strongly than others. The Kerr effect was discovered in 1875 by Scottish physicist John Kerr. Two special cases of the Kerr effect are normally considered, these being the Kerr electro-optic effect, or DC Kerr effect, and the optical Kerr effect, or AC Kerr effect. Kerr electro-optic effect The Kerr electro-optic effect, or DC Kerr effect, is the special case in which a slowly varying external electric field is applied by, for instance, a voltage on electrodes across the sample material. Under this influence, the sample becomes birefringent, ...
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Nicol Prism
A Nicol prism is a type of polarizer. It is an optical device made from calcite crystal used to convert ordinary light into plane polarized light. It is made in such a way that it eliminates one of the rays by total internal reflection, i.e. the ordinary ray is eliminated and only the extraordinary ray is transmitted through the prism. It was the first type of polarizing prism, invented in 1828 by William Nicol (1770–1851) of Edinburgh. Mechanism The Nicol prism consists of a rhombohedral crystal of Iceland spar (a variety of calcite) that has been cut at an angle of 68° with respect to the crystal axis, cut again diagonally, and then rejoined, using a layer of transparent Canada balsam as a glue. Unpolarized light ray enters through the side face of the crystal, and is split into two orthogonally polarized, differently directed rays by the birefringence property of calcite. The ''ordinary'' ray, or ''o''-ray, experiences a refractive index of ''n''o = 1.658 in ...
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Resistive Opto-isolator
Resistive opto-isolator (RO), also called photoresistive opto-isolator, vactrol (after a genericized trademark introduced by Vactec, Inc. in the 1960s), analog opto-isolatorIn PerkinElmer literature. or lamp-coupled photocell, is an optoelectronic device consisting of a source and detector of light, which are optically coupled and electrically isolated from each other. The light source is usually a light-emitting diode (LED), a miniature incandescent lamp, or sometimes a neon lamp, whereas the detector is a semiconductor-based photoresistor made of cadmium selenide (CdSe) or cadmium sulfide (CdS). The source and detector are coupled through a transparent glue or through the air. Electrically, RO is a resistance controlled by the current flowing through the light source. In the dark state, the resistance typically exceeds a few MOhm; when illuminated, it decreases as the inverse of the light intensity. In contrast to the photodiode and phototransistor, the photoresistor can operate ...
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Telephane
Henry Sutton (4 September 1855, Ballarat, Victoria – 28 July 1912) was an Australian designer, engineer, and inventor credited with contributions to early developments in electricity, aviation, wireless communication, photography and telephony. Branch is Sutton's great-granddaughter Early life Family Henry Sutton, the second of the eleven children of Richard Henry Sutton (1831 – 1876), and Mary Sutton (1835 – 1894), née Johnson, was born in a tent on the Ballarat goldfields on 4 September 1855. He had three brothers, with whom he was associated in the ''Sutton Brothers'' musical business originally centred on Ballarat,Sutton's Proprietary, Limited, ''The Ballarat Star'', (Saturday, 29 December 1900), p.1
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Ballarat, Australia
Ballarat ( ) () is a city in the Central Highlands of Victoria, Australia. At the 2021 census, Ballarat had a population of 111,973, making it the third-largest urban inland city in Australia and the third-largest city in Victoria. Within months of Victoria separating from the colony of New South Wales in 1851, gold was discovered near Ballarat, sparking the Victorian gold rush. Ballarat subsequently became a thriving boomtown that for a time rivalled Melbourne, the capital of Victoria, in terms of wealth and cultural influence. In 1854, following a period of civil disobedience in Ballarat over gold licenses, local miners launched an armed uprising against government forces. Known as the Eureka Rebellion, it led to the introduction of white male suffrage in Australia, and as such is interpreted as the origin of Australian democracy. The rebellion's symbol, the Eureka Flag, has become a national symbol. Proclaimed a city on 9 September 1870, Ballarat's prosperity, unlike tha ...
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Henry Sutton (inventor)
Henry Sutton (4 September 1855, Ballarat, Victoria – 28 July 1912) was an Australian designer, engineer, and inventor credited with contributions to early developments in electricity, aviation, wireless communication, photography and telephony. Branch is Sutton's great-granddaughter Early life Family Henry Sutton, the second of the eleven children of Richard Henry Sutton (1831 – 1876), and Mary Sutton (1835 – 1894), née Johnson, was born in a tent on the Ballarat goldfields on 4 September 1855. He had three brothers, with whom he was associated in the ''Sutton Brothers'' musical business originally centred on Ballarat,Sutton's Proprietary, Limited, ''The Ballarat Star'', (Saturday, 29 December 1900), p.1
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Rasterisation
In computer graphics, rasterisation (British English) or rasterization (American English) is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image (a series of pixels, dots or lines, which, when displayed together, create the image which was represented via shapes). The rasterized image may then be displayed on a computer display, video display or printer, or stored in a bitmap file format. Rasterization may refer to the technique of drawing 3D models, or to the conversion of 2D rendering primitives, such as polygons and line segments, into a rasterized format. Etymology The term "rasterisation" comes . 2D images Line primitives Bresenham's line algorithm is an example of an algorithm used to rasterize lines. Circle primitives Algorithms such as the midpoint circle algorithm are used to render circles onto a pixelated canvas. 3D images Rasterization is one of the typical techniques of rendering 3D models ...
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Nipkow Disk
A Nipkow disk (sometimes Anglicized as Nipkov disk; patented in 1884), also known as scanning disk, is a mechanical, rotating, geometrically operating image scanning device, patented by Paul Gottlieb Nipkow in Berlin. This scanning disk was a fundamental component in mechanical television, and thus the first televisions, through the 1920s and 1930s. Operation The device is a mechanically spinning disk of any suitable material (metal, plastic, cardboard, etc.), with a series of equally-distanced circular holes of equal diameter drilled in it. The holes may also be square for greater precision. These holes are positioned to form a single-turn spiral starting from an external radial point of the disk and proceeding to the center of the disk. When the disk rotates, the holes trace circular ring patterns, with inner and outer diameter depending on each hole's position on the disk and thickness equal to each hole's diameter. The patterns may or may not partially overlap, depending o ...
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