NationMaster - Encyclopedia: Mechanical television

Mechanical television was a television system that used mechanical or electromechanical devices to capture and display images. However, the images themselves were usually transmitted electronically and via radio waves. The reason for this dual nature of mechanical television lies in the history of technology. Mechanical television electronics came from nineteenth century inventors. Twentieth century inventors added electronics. Description Schematic drawing of a Nipkow disk Source: de:Bild:Nipkow-scheibe. ... Description Schematic drawing of a Nipkow disk Source: de:Bild:Nipkow-scheibe. ... A Nipkow disk is a mechanical, geometrically operating image scanning device (by itself, it performs neither image acquisition or reproduction), invented by Paul Gottlieb Nipkow, which was primarily used as a fundamental component in mechanical television. ... Mechanics (Greek ) is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. ... Electronics is the study of the flow of charge through various materials and devices such as, semiconductors, resistors, inductors, capacitors, nano-structures, and vacuum tubes. ...

Mechanical television in history

The mechanical part usually consists of a Nipkow disk, which has a series of holes in a spiral pattern. In the camera, the disk has a light-detecting device, usually a photoelectric cell, behind it. In the reproducer (the display), a modulated light source, usually a neon tube, replaces the light detector. As each hole flies by, it produces a scan line. An AM radio wave or closed circuit carries the scan line to the reproducer. A Nipkow disk is a mechanical, geometrically operating image scanning device (by itself, it performs neither image acquisition or reproduction), invented by Paul Gottlieb Nipkow, which was primarily used as a fundamental component in mechanical television. ... This article or section does not cite any references or sources. ... A scanline is a line on a CRT tube, made up of dots. ...

Facsimile transmission of still photographs first employed mechanical television principles in the 1800s. For instance, Shelford Bidwell demonstrated such a system in 1881. For decades, earlier systems had pioneered scanning in the transmission of type and line art. Photographic transmission was a greater challenge. The selenium in early photoelectric cells had very low sensitivity. Scanning a photograph at a resolution suitable for newspaper reproduction could take several minutes. With silhouette or duotone still images, instantaneous transmission was possible by 1909. Shelford Bidwell was an English physicist and inventor (1848â€“1909). ... Se redirects here. ...

Mechanical television transmitting a live, moving image in tone gradations (grayscale) was first demonstrated by Scottish inventor John Logie Baird on January 26, 1926, at his laboratory in London. Unlike later electronic systems with several hundred lines of resolution, Baird's vertically scanned image, using a scanning disk embedded with a double spiral of lenses, had only 30 lines, just enough to reproduce a recognizable human face. Bust of John Logie Baird in Helensburgh. ...

Because only a limited number of holes could be made in the disks, image resolution on mechanical television broadcasts was typically very low, ranging from about 30 lines up to 120 or so. A few systems ranging into the 200-line region also went on the air. Two of these were the 180-line system that Compagnie des Compteurs (CDC) installed in Paris in 1935, and the 180-line system that Peck Television employed at Canadian station VE9AK.

Actually, mechanical technology is quite capable of producing pictures with a thousand or more lines. The existence of high-resolution laser printers and scanners proves this point. Mechanical television technology made these printers and scanners possible. Yet in the 1930s, few people could see the way to high-resolution, mechanical pictures.

Instead of a Nipkow disk, mechanical television can use several other technologies. Other arrangements often made use of a rotating drum, either with holes or with a series of mirrors on it. A mirror, reflecting a vase. ...

Flying spot scanners

Another scanning method was the "flying spot." The flying spot developed as a remedy for the low sensitivity that photoelectric cells had at the time. A bright, narrow beam of light would shine through the holes of a Nipkow disk. This light would then illuminate the television subject, standing in a darkened studio. Whipping back and forth and up and down, the spot of light would complete sixteen or more scans per second. The light would reflect back to not one, but a bank of photoelectric cells. The combined signals of these cells gave a strong picture. Like mechanical television itself, flying spot technology grew out of phototelegraphy (facsimile). This scanning method began in the 1800s.

The BBC television service used the flying spot method until 1935. German television used flying spot methods as late as 1938. This year was by far not the end of flying spot scanner technology. The German inventor Manfred von Ardenne designed a flying spot scanner with a CRT as the light source. In the 1950s, DuMont marketed Vitascan, an entire flying-spot color studio system. Today, graphic scanners still use this scanning method. The flying spot method has two disadvantages... Manfred von Ardenne (January 20, 1907 - May 26, 1997) was a German inventor. ... Dumont is a very common family name in France. ...

A note about outdoor telecasts with a flying spot scanner: In 1928, Ray Kell from the United States' GE proved that flying spot scanners can work outdoors. The scanning light source must be brighter than other incident illumination. Kell was the engineer who ran a 24-line camera that telecast pictures of New York Governor Al Smith. Smith was accepting the Democratic nomination for presidency. As Smith stood outside the capital in Albany, Kell managed to send usable pictures to his associate Bedford at station WGY. WGY was broadcasting Smith's speech. The rehearsal went well, but then the real event began. The newsreel cameramen switched on their floodlights. Unfortunately for Kell, his scanner only had a 1-kW lamp inside it. The floodlights threw much more light on Governor Smith. These floods simply overwhelmed Kell's image. In fact, the floods made the unscanned part of the image as bright as the scanned part. Kell's photocells couldn't pick up reflections off Smith from the AC scanning beam. Instead, the photocells only detected the flat, DC light from the floodlamps. The effect is very similar to extreme overexposure in a still camera: The scene disappears, and the camera records a flat, bright light. Use the camera in favorable conditions, though, and the picture comes out fine. Similarly, Kell proved that outdoors in favorable conditions, his scanner worked fine.

Mechanical television with large pictures

A few mechanical TV systems could produce images several feet wide and of comparable quality to the cathode ray tube (CRT) televisions that were to follow. CRT technology at that time was limited to small, low-brightness screens. Perhaps the best mechanical televisions of the 1930s used the Scophony system, which could produce images of more than 400 lines and display them on screens at least 9×12 feet (2.8×3.7 m) in size (at least a few models of this type were actually produced). The Scophony system used multiple drums rotating at fairly high speed to create the images. One using a 441-line American standard of the day had a small drum rotating at 39,690 rpm (a second slower drum moved at just a few hundred rpm). Today, DLP mechanical TV technology from Texas Instruments far outstrips the capabilities of the Scophony system. Scophony was a sophisticated mechanical television system developed in Britain. ... rpm or RPM may mean: revolutions per minute RPM Package Manager (originally called Red Hat Package Manager) RPM (movie) RPM (band), a Brazilian rock band RPM (magazine), a former Canadian music industry magazine In firearms, Rounds Per Minute: how many shots an automatic weapon can fire in one minute On... The DLP Logo Digital Light Processing (DLP) is a technology used in projectors and video projectors. ... Texas Instruments (NYSE: TXN), better known in the electronics industry (and popularly) as TI, is an American company based in Dallas, Texas, USA, renowned for developing and commercializing semiconductor and computer technology. ...

Aspect ratios for different purposes

Some mechanical equipment scanned lines vertically rather than horizontally, as in modern TVs. An example of this method is the Baird 30-line system. Baird's British system created a picture in the shape of a very narrow, vertical rectangle. This shape created a portrait image, instead of the landscape orientation that is common today. The position of a framing mask before the Nipkow disk determines the scan line orientation. Placement of the framing mask at the left or right side of the disk gives vertical scan lines. Placement at the top or bottom of the disk gives horizontal scan lines. Baird's earliest television images had very low definition. These images could only show one person clearly. For this reason, a vertical portrait image made more sense to Baird than a horizontal, landscape image. Baird chose a shape three units wide by seven high. You can imagine this shape this way: Pictures this narrow might fit onto the spine of a dictionary. Horizontal is an orientation relating to, or in parallel with the horizon, and thus perpendicular to the vertical. ... A portrait is a painting, photograph, or other artistic representation of a person or object. ... This article does not cite its references or sources. ...

Instead of entertainment television, Baird might have had point-to-point communication in mind. Another television system followed that reasoning. Herbert Ives' 1927 AT&T, large-screen television system was the most advanced television of its day. This 50-line system also produced a portrait picture. Since AT&T intended to use television for telephony, the vertical shape was logical: Phone calls are usually conversations between just two people. A picturephone system would depict one person on each side of the line.

Meanwhile, in the US, Germany and elsewhere, other inventors planned to use television for entertainment purposes. These inventors began with square or landscape pictures. (For example, consider the television systems of Ernst Alexanderson, Frank Conrad, Charles Jenkins, William Peck and Ulises Sanabria.) These inventors realized that television is about relationships between people. From the very beginning, these inventors allowed picture space for two-shots. Soon, images increased to 60 lines or more. The camera could easily photograph several people at once. Then even Baird switched his picture mask to a horizontal image. Baird's "zone television" is an early example of rethinking his extremely narrow screen format. For entertainment and most other purposes, even today, landscape remains the more practical shape. Ernst Frederick Werner Alexanderson (January 25, 1878â€“May 14, 1975) was a Swedish-American electrical engineer. ... Dr. Frank Conrad (1874-1941) was a radio broadcasting pioneer who worked as the Assistant Chief Engineer for the Westinghouse Electric Company in Pittsburgh, Pennsylvania. ... The name Charles Jenkins may refer to: Charles Robert Jenkins is a United States soldier who had lived in North Korea and married Hitomi Soga Charles Lamont Charlie Jenkins is an American track athlete This is a disambiguation page — a navigational aid which lists other pages that might otherwise...

Rise of electronic television

The advancement of all-electronic television (including image dissectors and other camera tubes and cathode ray tubes for the reproducer) marked the beginning of the end for mechanical systems as the dominant form of television. Mechanical TV usually only produced small images. It was the main type of TV until the 1930s. All-electronic television, first demonstrated publicly by Philo Farnsworth in 1934, and first used for broadcasting in 1936, was quickly advancing past this point, reaching 400 to more than 600 lines with fast field scan rates in the next few decades. The last mechanical television broadcasts ended in 1939 at stations run by a handful of public universities in the United States. In older video cameras, before the 1990s, a video camera tube or pickup tube was used instead of a charge-coupled device (CCD). ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT Electron guns Electron beams Focusing coils Deflection coils Anode connection Mask for separating beams for red, green, and blue part of displayed image Phosphor layer with red, green, and blue zones Close-up of the phosphor... Philo Taylor Farnsworth (August 19, 1906 â€“ March 11, 1971) was an American inventor best known for being the first person to demonstrate and patent a working electronic television system, a system which still serves as the basis for all modern television devices. ...

Color mechanical television

Of course, simultaneous color systems superceded the CBS-Goldmark system. Yet mechanical color methods continued to find uses. Early color sets were very expensive, over $1,000 in the money of the time. Inexpensive adapters allowed owners of black-and-white, NTSC television sets to receive color telecasts. The most prominent of these adapters is Col-R-Tel, a 1955 NTSC to field-sequential converter. This system operates at NTSC scanning rates, but uses a disc like the obsolete CBS system had. The disc converts the black-and-white set to a field-sequential set. Meanwhile, Col-R-Tel electronics recover NTSC color signals and sequence them for disc reproduction. The electronics also synchronize the disc to the NTSC system. In Col-R-Tel, the electronics provide the saturation values (chroma). These electronics cause chroma values to superimpose over brightness (luminance)changes of the picture. The disc paints the hues (color) over the picture. Peter Goldmark, Columbia Records engineer and developer of the long-playing 33-1/3 rpm vinyl discs which defined home audio for two generations. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ...

A few years after Col-R-Tel, Apollo moon missions also adopted field-sequential techniques. The lunar color cameras all had color wheels. These Westinghouse and later RCA cameras sent field-sequential color television pictures to earth. The earth receiving stations included mechanical equipment that converted these pictures to standard television formats. The name Westinghouse can refer to any number of devices and independent businesses that can trace their roots to the work of George Westinghouse: // People George Westinghouse, founder of Westinghouse Electric Corporation Devices Westinghouse air brake. ... RCAs logo as seen today on many products. ...

Mechanical television recording

In the days of commercial mechanical television transmissions, a system of recording images (but not sound) was developed, using a modified gramaphone recorder. Marketed as "Phonovision", this system, which was never fully perfected, proved to be complicated to use as well as quite expensive, yet managed to preserve a number of early broadcast images that would normally have been lost. Scottish computer engineer Donald F. McLean has painstakingly reconstructed the analogue playback technology required to view these recordings, and has given lectures and presentations on his collection of mechanical television recordings made between 1925 and 1933. [1] Phonovision, an experimental process for recording a television signal on phonograph records, was developed in the late 1920s in England by British television pioneer John Logie Baird. ...

Among the discs in Dr. McLean's collection are a number of test recordings made by television pioneer John Logie Baird himself. One disc, dated "28th March 1928" and marked with the title "Miss Poundsford", shows several minutes of a woman's face in what appears to be very animated conversation. The woman was identified in 1993 to be Mabel Poundsford, and her brief appearance on the disc is one of the earliest known video recordings of a human being. [2] Bust of John Logie Baird in Helensburgh. ...

Recent uses of mechanical television

Since the 1970s, some amateur radio enthusiasts have experimented with mechanical systems. The early light source of a neon lamp has now been replaced with super-bright LEDs. There is some interest in creating these systems for narrow-bandwidth television, which would allow a small moving image to fit into a channel less than 40 kHz wide (modern TV systems usually have a channel about 6 MHz wide, 150 times larger). Also associated with this is slow-scan TV, although that typically uses electronic systems. The 1970s decade refers to the years from 1970 to 1979. ... Amateur radio station with modern solid-state transceiver featuring LCD display and DSP capabilities Amateur radio, often called Ham radio, is a hobby enjoyed by about six million people[1] throughout the world. ... Lighting neon lamp, two 220/230 volt and 110 V neon lamps and a screwdriver with neon lamp inside A neon lamp is a gas discharge lamp containing primarily neon gas at low pressure. ... Led is also the past tense of the verb to lead Blue, green and red LEDs. ... Narrow-bandwidth television (NBTV) is a type of television designed to fit into a low-bandwidth channel, in the extreme case using amateur radio voice frequency channels that only range up to a few kilohertz (though channels ranging into a few tens of kilohertz and beyond can also be used). ... Slow-scan television (SSTV) is used by amateur radio operators, to transmit and receive static pictures in monochrome (black & white) or colour. ...

The re-emergence of mechanical TV techniques

Today, a mechanical system of a sort has seen moderate popularity. DLP (Digital Light Processing) projectors use an array of tiny (16 μm²) electrostatically-actuated mirrors selectively reflecting a light source to create an image. Many low-end DLP systems also use a color wheel to provide a sequential color image, a common feature of many early color television systems before the shadow mask CRT provided a practical method for producing a simultaneous color image. For political parties using this acronym, see Democratic Labour Party. ... Electrostatics (also known as Static Electricity) is the branch of physics that deals with the forces exerted by a static (i. ... An illustration of a color wheel, pointing out the primary, secondary and tertiary colors. ... The shadow mask is one of two major technologies used to manufacture cathode ray tube (CRT) televisions and computer displays that produce color images (the other is aperture grille). ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT Electron guns Electron beams Focusing coils Deflection coils Anode connection Mask for separating beams for red, green, and blue part of displayed image Phosphor layer with red, green, and blue zones Close-up of the phosphor...

Another place where high-quality imagery is produced by opto-mechanics is the laser printer, where a small rotating mirror is used to deflect a modulated laser beam in one axis while the motion of the photoconductor provides the motion in the other axis. A modification of such a system using high power lasers is used in laser video projectors, with resolutions as high as 1024 lines and each line containing >1500 points. Such systems produce, arguably, the best quality video images. They are used, for instance, in planetariums. 1993 Apple LaserWriter Pro 630 laser printer A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. ... A photoresistor is an electronic component whose resistance decreases with increasing incident light intensity. ... // A planetarium is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation. ...

Laser lighting display techniques are combined with computer emulation in the LaserMAME project. It is a vector-based system, unlike the raster displays thus-far described. Laser light reflected off of computer-controlled mirrors is used to trace out images generated by classic arcade software which is executed by a specially modified version of the MAME emulation software. Copper Bromide laser in operation. ... This article is about emulation in computer science. ... Look up vector in Wiktionary, the free dictionary. ... Suppose the smiley face in the top left corner is an RGB bitmap image. ... Experiment with a laser (likely an argon type) (US Military) In physics, a laser is a device that emits light through a specific mechanism for which the term laser is an acronym: light amplification by stimulated emission of radiation. ... Arcade can mean several things: Arcade (architecture) - A passage or walkway, often including retailers. ... MAME is an emulator application designed to recreate the hardware of arcade game systems in software, with the intent of preserving gaming history and preventing vintage games from being lost or forgotten. ... Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ...

External links

Categories: Television technology | History of television A video format describes how one device sends a video pictures to another device, such as the way that a DVD player sends pictures to a television, or a computer to a monitor. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... NTSC-J is a videogame region which covers Japan. ... PAL-M is the TV system used in Brazil. ... Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... PALplus is an extension of the PAL analogue broadcasting system for transmitting 16:9 programs without sacrificing vertical resolution. ... SECAM, also written SÃ‰CAM (SÃ©quentiel couleur Ã mÃ©moire, French for Sequential Color with Memory), is an analog color television system first used in France. ... A number of experimental and broadcast pre World War II systems were tested. ... 405 line is the name of a monochrome analogue television broadcasting system in operation in the UK between 1936 and 1985, and also used for some time in Ireland and Hong Kong. ... Historically, the term high-definition television was first used to refer to television standards developed in the 1930s to replace early experimental systems with as few as 12 lines. ... Multiplexed Analogue Components (MAC) is a high-definition television transmission standard, originally proposed in 1995 for European HDTV. MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video). ... Japan had the earliest working HDTV system, with design efforts going back to 1979. ... Multichannel television sound, better known as MTS (often still as BTSC, for the Broadcast Television Systems Committee that created it), is the method of encoding three additional channels of audio into an NTSC-format audio carrier. ... NICAM (known also as NICAM 728, after the 728 kbit/s bitstream it is sent over), Near Instantaneous Companded Audio Multiplex, is a format for digital sound on analogue television transmissions. ... Zweikanalton (two channel sound) is a television sound transmission system used in Germany and other countries. ... A commonly-used symbol indicating that a program or movie is closed-captioned. ... A BBC Ceefax page from January 9, 2007. ... CGMS-A (Copy Generation Management System Analogue) is a copy protection mechanism for analog television signals. ... Ghost-canceling reference, or GCR, is a special sub-signal on a television channel that receivers can use to attenuate the ghosting effect of a television signal split into multiple paths between transmitter and receiver. ... This article is about PDC/StarText teletext programme listings. ... The vertical blanking interval (VBI) is an interval in a television or VDU signal that temporarily suspends transmission of the signal for the electron gun to move back up to the first line of the television screen to trace the next screen field. ... Video Encoded Invisible Light (VEIL) is a technology for encoding low-bandwidth digital data bitstream in video signal, developed by VEIL Interactive Technologies. ... Vertical interval timecode (VITC, pronounced vitsee or sometimes vits) is a form of SMPTE timecode embedded as black-and-white bars in a pair of the normally unseen vertical interval lines in a television signal. ... In television technology, widescreen signaling (WSS) is a digital stream embedded in the TV signal describing qualities of the broadcast, in particular the intended aspect ratio of the image. ... Extended Data Services (now XDS, previously EDS), is an American standard classified under Electronic Industries Alliance standard EIA-766 for the delivery of any ancillary data (metadata) to be sent with an analog television program, or any other NTSC video signal. ... Standard-definition television or SDTV refers to television systems that have a lower resolution than HDTV systems. ... 480i is the shorthand name for a video mode. ... 576i is the shorthand name for a video mode. ... Projection screen in a home theater, displaying a high-definition television image. ... 1080i is shorthand name for a category of video modes. ... Low-definition television or LDTV refers to television systems that have a lower resolution than Standard Definition Television systems. ... ... ... Official 1seg logo 1seg (Katakana: ãƒ¯ãƒ³ã‚»ã‚°) is a mobile terrestrial digital audio/video and data broadcasting service in Japan. ... Enhanced-definition television, extended-definition television, or EDTV is a CEA marketing shorthand term for certain digital television (DTV) formats. ... 480p is the shorthand name for a video mode. ... 576p is the shorthand name for a video mode. ... Projection screen in a home theater, displaying a high-definition television image. ... JOHN HERMAN SUCKS FAT DICK ... 1080p is the shorthand name for a category of video modes. ... Official DVB logo, found on compliant devices DVB, short for Digital Video Broadcasting, is a suite of internationally accepted, open standards for digital television maintained by the DVB Project, an industry consortium with more than 270 members, and published by a Joint Technical Committee (JTC) of European Telecommunications Standards Institute... MPEG-2 is a standard for the generic coding of moving pictures and associated audio information [1]. It is widely used around the world to specify the format of the digital television signals that are broadcast by terrestrial (over-the-air), cable, and direct broadcast satellite TV systems. ... The Advanced Television Systems Committee (ATSC) is the group that helped to develop the new digital television standard for the United States, also adopted by Canada, Mexico, and South Korea and being considered by other countries. ... DVB-T stands for Digital Video Broadcasting - Terrestrial and it is the DVB European consortium standard for the broadcast transmission of digital terrestrial television. ... Integrated Services Digital Broadcasting (ISDB) is the digital television (DTV) and digital audio broadcasting (DAB) format. ... MPEG-4 is a standard used primarily to compress audio and visual (AV) digital data. ... This article or section is in need of attention from an expert on the subject. ... Advanced Audio Coding (AAC) is a standardized, lossy compression and encoding scheme for digital audio. ... Multichannel audio is the name for a variety of techniques for expanding and enriching the sound of audio playback by recording additional sound channels that can be reproduced on additional speakers. ... MP2, also known as Musicam, is a short form of MPEG Audio Layer II, and it is also used as a file extension for files containing audio data of this type. ... Pulse-code modulation (PCM) is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital (usually binary) code. ... Linear Pulse Code Modulation used in communications (or LPCM) is a format that is a popular choice in music production. ... A commonly-used symbol indicating that a program or movie is closed-captioned. ... A BBC Ceefax page from January 9, 2007. ... This is the Content Protection and Copy Management standard being developed by the DVB Project (http://www. ... A broadcast flag is a set of status bits (or flags) sent in the data stream of a digital television program that indicates whether or not it can be recorded, or if there are any restrictions on recorded content. ... In television technology, Active Format Descriptor or Active Format Description (AFD) is a signal that broadcasters will transmit with the picture to enable 4:3 and 16:9 television sets to display picture in the intended aspect ratio. ... The Sky Digital EPG in the United Kingdom and Republic of Ireland. ... This article is about digital presentation. ... Super Hi-Vision, also known as Ultra High Definition Video or UHDV is a digital video format, currently proposed by NHK of Japan. ... There are very few or no other articles that link to this one. ... Super Hi-Vision, also known as Ultra High Definition Video or UHDV and UHD is a digital video format, currently proposed by NHK of Japan. ... 22. ... Multiple MPEG programs are combined then sent to a transmitting antenna. ... Converting between a different numbers of pixels and different frame rates in video pictures is a complex technical problem. ... Video processing techniques are used in video codecs, video players and other devices. ... Video on demand (VOD) systems allow users to select and watch video content over a network as part of an interactive television system. ...

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