The Iconoscope (from the Greek: εἰκών "image" and σκοπεῖν "to look, to see") was the first practical video camera tube to be used in early television cameras. The iconoscope produced a much stronger signal than earlier mechanical designs, and could be used under any well-lit conditions. This was the first fully electronic system to replace earlier cameras, which used special spotlights or spinning disks to capture light from a single very brightly lit spot.
Some of the principles of this apparatus were described when Vladimir Zworykin filed two patents for a Television system in 1923 and 1925. A research group at RCA headed by Zworykin presented the iconoscope to the general public in a press conference in June 1933, and two detailed technical papers were published in September and October of the same year. The German company Telefunken bought the rights from RCA and built the superikonoskop camera used for the historical TV transmission at the 1936 Summer Olympics in Berlin.
The iconoscope was replaced in Europe around 1936 by the much more sensitive Super-Emitron and Superikonoskop, while in the United States the Iconoscope was the leading camera tube used for broadcasting from 1936 until 1946, when it was replaced by the image orthicon tube.
The main image forming element in the iconoscope was a mica plate with a pattern of photosensitive granules deposited on the front using an electrically insulating glue. The granules were typically made of silver grains covered with caesium or caesium oxide. The back of the mica plate, opposite the granules, was covered with a thin film of silver. The separation between the silver on the back of the plate and the silver in the granules caused them to form individual capacitors, able to store electrical charge. These were typically deposited as small spots, creating pixels. The system as a whole was referred to as a "mosaic".
The system is first charged up by scanning the plate with an electron gun similar to one in a conventional television display tube. This process deposits charges into the granules, which in a dark room would slowly decay away at a known rate. When exposed to light, the photosensitive coating releases electrons which are supplied by the charge stored in the silver. The emission rate increases in proportion to the intensity of the light. Through this process, the plate forms an electrical analog of the visual image, with the stored charge representing the inverse of the average brightness of the image at that location.
When the electron beam scans the plate again, any residual charge in the granules resists refilling by the beam. The beam energy is set so that any charge resisted by the granules is reflected back into the tube, where it is collected by the collector ring, a ring of metal placed around the screen. The charge collected by the collector ring varies in relation to the charge stored in that location. This signal is then amplified and inverted, and then represents a positive video signal.
The collector ring is also used to collect electrons being released from the granules in the photoemission process. If the gun is scanning a dark area few electrons would be released directly from the scanned granules, but the rest of the mosaic will also be releasing electrons that will be collected during that time. As a result, the black level of the image will float depending on the average brightness of the image, which caused the iconoscope to have a distinctive patchy visual style. This was normally combatted by keeping the image continually and very brightly lit. This also led to clear visually differences between scenes shot indoors and those shot outdoors in good lighting conditions.
As the electron gun and the image itself both have to be focused on the same side of the tube, some attention has to be paid to the mechanical arrangement of the components. Iconocopes were typically built with the mosaic inside a cylindrical tube with flat ends, with the plate positioned in front of one of the ends. A conventional movie camera lens was placed in front of the other end, focussed on the plate. The electron gun was then placed below the lens, tilted so that it was also aimed at the plate, although at an angle. This arrangement has the advantage that both the lens and electron gun lie in front of the imaging plate, which allows the system to be compartmentalized in a box-shaped enclosure with the lens completely within the case.
As the electron gun is tilted compared to the screen, its image of the screen is not as a rectangular plate, but a keystone shape. Additionally, the time needed for the electrons to reach the upper portions of the screen was longer than the lower areas, which were closer to the gun. Electronics in the camera adjusted for this effect by slightly changing the scanning rates.
The accumulation and storage of photoelectric charges during each scanning cycle greatly increased the electrical output of the iconoscope relative to non-storage type image scanning devices. In the 1931 version, the electron beam scanned the granules; while in the 1925 version, the electron beam scanned the back of the image plate.
The problem of low sensitivity to light resulting in low electrical output from transmitting or "camera" tubes would be solved with the introduction of charge-storage technology by the Hungarian engineer Kálmán Tihanyi in the beginning of 1925. His solution was a camera tube that accumulated and stored electrical charges ("photoelectrons") within the tube throughout each scanning cycle. The device was first described in a patent application he filed in Hungary in March 1926 for a television system he dubbed "Radioskop". After further refinements included in a 1928 patent application, Tihanyi's patent was declared void in Great Britain in 1930, and so he applied for patents in the United States.
Zworykin presented in 1923 his project for a totally electronic television system to the general manager of Westinghouse. In July 1925, Zworykin submitted a patent application for a "Television System" that includes a charge storage plate constructed of a thin layer of isolating material (aluminum oxide) sandwiched between a screen (300 mesh) and a colloidal deposit of photoelectric material (potassium hydride) consisting of isolated globules. The following description can be read between lines 1 and 9 in page 2: The photoelectric material, such as potassium hydride, is evaporated on the aluminum oxide, or other insulating medium, and treated so as to form a colloidal deposit of potassium hydride consisting of minute globules. Each globule is very active photoelectrically and constitutes, to all intents and purposes, a minute individual photoelectric cell. Its first image was transmitted in late summer of 1925, and a patent was issued in 1928. However the quality of the transmitted image failed to impress to H P Davis, the general manager of Westinghouse, and Zworykin was asked to work on something useful. A patent for a television system was also filed by Zworykin in 1923, but this file is not a reliable bibliographic source because extensive revisions were done before a patent was issued fifteen years later and the file itself was divided into two patents in 1931.
The first practical iconoscope was constructed in 1931 by Sanford Essig, when he accidentally left one silvered mica sheet in the oven too long. Upon examination with a microscope, he noticed that the silver layer had broken up into a myriad of tiny isolated silver globules. He also noticed that: the tiny dimension of the silver droplets would enhance the image resolution of the iconoscope by a quantum leap. As head of television development at Radio Corporation of America (RCA), Zworykin submitted a patent application in November 1931, and it was issued in 1935. Nevertheless, Zworykin's team was not the only engineering group working on devices that use a charge stage plate. In 1932, Tedham and McGee under the supervision of Isaac Shoenberg applied for a patent for a new device they dubbed "the emitron", a 405-line broadcasting service employing the super-emitron began at studios in Alexandra Palace in 1936, and a patent was issued in the USA in 1937. One year later, in 1933, Philo Farnsworth also applied for a patent for a device that use a charge storage plate and a low-velocity electron scanning beam, a patent was issued in 1937, but Farnsworth did not know that the low-velocity scanning beam must land perpendicular to the target and he never actually built such a tube.
The iconoscope was presented to the general public in a press conference in June 1933, and two detailed technical papers were published in September and October of the same year. Unlike the Farnsworth image dissector, the Zworykin iconoscope was much more sensitive, useful with an illumination on the target between 4ft-c (43lx) and 20ft-c (215lx). It was also easier to manufacture and produced a very clear image. The iconoscope was the primary camera tube used in American broadcasting from 1936 until 1946, when it was replaced by the image orthicon tube.
On the other side of the Atlantic Ocean, the British team formed by engineers Lubszynski, Rodda, and MacGee developed the super-emitron (also superikonoscop in Germany) in 1934, this new device is between ten and fifteen times more sensitive than the original emitron and iconoscope, and it was used for a public broadcasting by the BBC, for the first time, on Armistice Day 1937. The image iconoscope was the representative of the European tradition in electronic tubes competing against the American tradition represented by the image orthicon.
Picture of the iconoscope camera used at the Olympic Games Berlin, 1936
180 lines (by modern standards it could be called 169p) is an early electronic television system. It was used in Germany after on March 22, 1935, using telecine transmission of film, intermediate film system, or cameras using the Nipkow disk. Simultaneously, fully electronic transmissions using cameras based on the iconoscope began on January 15, 1936 with a definition of 375 lines.
The Berlin Summer Olympic Games were televised, using both closed-circuit 375 lines fully electronic iconoscope-based cameras and 180 lines intermediate film cameras transmitting to Berlin, Hamburg, Munich, Nuremberg and Bayreuth via special Reichspost long distance cables in August 1936. In Berlin, twenty-eight public 180 lines television rooms were opened for anybody who did not own a television set. After February 1937 both 180 and 375 lines systems were replaced by a superior 441-line system.1933 in science
The year 1933 in science and technology involved some significant events, listed below.1943 in television
The year 1943 in television involved some significant events.
Below is a list of television-related events during 1943.Donald Bitzer
Donald L. Bitzer (born January 1, 1934) is an American electrical engineer and computer scientist. He was the co-inventor of the plasma display, is largely regarded as the "father of PLATO", and has made a career of improving classroom productivity by using computer and telecommunications technologies.
He received three degrees in electrical engineering (B.S., 1955; M.S., 1956; Ph.D., 1960) from the University of Illinois at Urbana-Champaign.Bitzer holds patents for inventions including the plasma-display panel, the binary-weighted solenoid, a high-quality modem, and new satellite communications techniques. The creation of the PLATO computer system, the first system to combine graphics and touch-sensitive screens, is the hallmark of his efforts.
Bitzer co-invented the flat plasma display panel in 1964. Originally invented as an educational aid to help students working in front of computers for long periods of time, plasma screens do not flicker and are a significant advance in television technology. The display was also a way of overcoming the limited memory of the computer systems being used. In 1973 the National Academy of Engineering presented Bitzer with the Vladimir K. Zworykin Award, which honors the inventor of the iconoscope. The invention won the Industrial Research 100 Award in 1966.
A member of the National Academy of Engineering since 1974, Bitzer was designated a National Associate by the National Academies in 2002. In October the same year, he was awarded an Emmy by the National Academy of Television Arts and Sciences for his efforts in advancing television technology. He is also a Computer Society Fellow of the Institute of Electrical and Electronics Engineers and a member of the American Society for Engineering Education.
Following several decades on the faculty of UIUC's College of Engineering, Bitzer is currently a Distinguished University Research Professor of Computer Science at North Carolina State University.First Draft of a Report on the EDVAC
The First Draft of a Report on the EDVAC (commonly shortened to First Draft) is an incomplete 101-page document written by John von Neumann and distributed on June 30, 1945 by Herman Goldstine, security officer on the classified ENIAC project. It contains the first published description of the logical design of a computer using the stored-program concept, which has controversially come to be known as the von Neumann architecture.History of television
The invention of the television was the work of many individuals in the late 19th century and early 20th century. Individuals and corporations competed in various parts of the world to deliver a device that superseded previous technology. Many were compelled to capitalize on the invention and make profit, while some wanted to change the world through visual and audio communication technology.Image dissector
An image dissector, also called a dissector tube, is a video camera tube in which photocathode emissions create an "electron image" which is then scanned to produce an electrical signal representing the visual image. The term may apply specifically to a dissector tube employing magnetic fields to keep the electron image in focus, and an electron multiplier to scan the electrons. Dissectors were used only briefly in television systems before being replaced by the much more sensitive iconoscope during the 1930s.July 29
July 29 is the 210th day of the year (211th in leap years) in the Gregorian calendar. 155 days remain until the end of the year.Kálmán Tihanyi
Kálmán Tihanyi (28 April 1897 – 26 February 1947) was a Hungarian physicist, electrical engineer and inventor. One of the early pioneers of electronic television, he made significant contributions to the development of cathode ray tubes (CRTs), which were bought and further developed by the Radio Corporation of America (later RCA), and German companies Loewe and Fernseh AG. He invented and designed the world's first automatic pilotless aircraft in Great Britain.R. A. McConnell
Robert A. McConnell (1914—2006) was an American physicist and parapsychologist.
McConnell was born in Pennsylvania in 1914, and studied at Carnegie Institute of Technology obtaining a B.S. in physics in 1935 and a Ph.D. from the University of Pittsburgh in 1947. He worked as a physicist at a U.S. Naval aircraft factory and at the Massachusetts Institute of Technology Radiation Laboratory. He also worked in radar moving target indication, iconoscope, and ultrasonic microwaves.He earned a Doctor of Philosophy degree in engineering physics. McConnell was the first president of the Parapsychological Association and a Fellow of the American Psychological Society. He was Research Professor Emeritus of Biological Sciences at the University of Pittsburgh.Samson (Fox Feature Syndicate)
Samson is a fictional superhero that appeared in comic books published by Fox Feature Syndicate. He first appeared in Fantastic Comics #1 (Dec. 1939). The writer was uncredited, but is believed to be Will Eisner; the artist was Alex Blum, using the pseudonym "Alex Boon".Television
Television (TV), sometimes shortened to tele or telly, is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in color, and in two or three dimensions and sound. The term can refer to a television set, a television program ("TV show"), or the medium of television transmission. Television is a mass medium for advertising, entertainment and news.
Television became available in crude experimental forms in the late 1920s, but it would still be several years before the new technology would be marketed to consumers. After World War II, an improved form of black-and-white TV broadcasting became popular in the United States and Britain, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion. In the mid-1960s, color broadcasting was introduced in the US and most other developed countries. The availability of multiple types of archival storage media such as Betamax, VHS tape, local disks, DVDs, flash drives, high-definition Blu-ray Discs, and cloud digital video recorders has enabled viewers to watch pre-recorded material—such as movies—at home on their own time schedule. For many reasons, especially the convenience of remote retrieval, the storage of television and video programming now occurs on the cloud. At the end of the first decade of the 2000s, digital television transmissions greatly increased in popularity. Another development was the move from standard-definition television (SDTV) (576i, with 576 interlaced lines of resolution and 480i) to high-definition television (HDTV), which provides a resolution that is substantially higher. HDTV may be transmitted in various formats: 1080p, 1080i and 720p. Since 2010, with the invention of smart television, Internet television has increased the availability of television programs and movies via the Internet through streaming video services such as Netflix, Amazon Video, iPlayer and Hulu.
In 2013, 79% of the world's households owned a television set. The replacement of early bulky, high-voltage cathode ray tube (CRT) screen displays with compact, energy-efficient, flat-panel alternative technologies such as LCDs (both fluorescent-backlit and LED), OLED displays, and plasma displays was a hardware revolution that began with computer monitors in the late 1990s. Most TV sets sold in the 2000s were flat-panel, mainly LEDs. Major manufacturers announced the discontinuation of CRT, DLP, plasma, and even fluorescent-backlit LCDs by the mid-2010s. In the near future, LEDs are expected to be gradually replaced by OLEDs. Also, major manufacturers have announced that they will increasingly produce smart TVs in the mid-2010s. Smart TVs with integrated Internet and Web 2.0 functions became the dominant form of television by the late 2010s.Television signals were initially distributed only as terrestrial television using high-powered radio-frequency transmitters to broadcast the signal to individual television receivers. Alternatively television signals are distributed by coaxial cable or optical fiber, satellite systems and, since the 2000s via the Internet. Until the early 2000s, these were transmitted as analog signals, but a transition to digital television is expected to be completed worldwide by the late 2010s. A standard television set is composed of multiple internal electronic circuits, including a tuner for receiving and decoding broadcast signals. A visual display device which lacks a tuner is correctly called a video monitor rather than a television.Television Spy
Television Spy is a 1939 American drama film directed by Edward Dmytryk and starring William Henry.Television guidance
Television guidance (TGM) is a type of missile guidance system using a television camera in the missile or glide bomb that sends its signal back to the launch platform. There, a weapons officer or bomb aimer watches the image on a television screen and sends corrections to the missile, typically over a radio control link. Television guidance is not a seeker because it is not automated, although semi-automated systems with autopilots to smooth out the motion are known. They should not be confused with contrast seekers, which also use a television camera but are true automated seeker systems.
The concept was first explored by the Germans during World War II as an anti-shipping weapon that would keep the launch aircraft safely out of range of the target's anti-aircraft guns. The best-developed example was the Henschel Hs 293, but the TV guided versions did not see operational use. The US also experimented with similar weapons during the war, notably the GB-4 and Interstate TDR. Only small numbers were used experimentally and with poor results. One of the first TV guided weapons to see widespread service was the Anglo-French Martel missile, which came in radar-seeking and TV-guided versions. The US AGM-62 Walleye is a similar system attached to an unpowered bomb, the Soviet Kh-29 is similar.
Television guidance was never widely used, as the introduction of laser guided bombs and GPS weapons have generally replaced them. However, they remain useful when certain approaches or additional accuracy are needed. One famous use was the attack on the Sea Island oil platform during the Gulf War, which required pinpoint accuracy.Video camera
A video camera is a camera used for electronic motion picture acquisition (as opposed to a movie camera, which records images on film), initially developed for the television industry but now common in other applications as well.
The earliest video cameras were those of John Logie Baird, based on the mechanical Nipkow disk and used in experimental broadcasts through the 1910s–1930s. All-electronic designs based on the video camera tube, such as Vladimir Zworykin's Iconoscope and Philo Farnsworth's image dissector, supplanted the Baird system by the 1930s. These remained in wide use until the 1980s, when cameras based on solid-state image sensors such as CCDs (and later CMOS active pixel sensors) eliminated common problems with tube technologies such as image burn-in and made digital video workflow practical. The transition to digital TV gave a boost to digital video cameras and by the 2010s, most video cameras were digital.
With the advent of digital video capture, the distinction between professional video cameras and movie cameras has disappeared as the intermittent mechanism has become the same. Nowadays, mid-range cameras exclusively used for television and other work (except movies) are termed professional video cameras.
Video cameras are used primarily in two modes. The first, characteristic of much early broadcasting, is live television, where the camera feeds real time images directly to a screen for immediate observation. A few cameras still serve live television production, but most live connections are for security, military/tactical, and industrial operations where surreptitious or remote viewing is required. In the second mode the images are recorded to a storage device for archiving or further processing; for many years, videotape was the primary format used for this purpose, but was gradually supplanted by optical disc, hard disk, and then flash memory. Recorded video is used in television production, and more often surveillance and monitoring tasks in which unattended recording of a situation is required for later analysis.
Modern video cameras have numerous designs and uses.
Professional video cameras, such as those used in television production, may be television studio-based or mobile in the case of an electronic field production (EFP). Such cameras generally offer extremely fine-grained manual control for the camera operator, often to the exclusion of automated operation. They usually use three sensors to separately record red, green and blue.
Camcorders combine a camera and a VCR or other recording device in one unit; these are mobile, and were widely used for television production, home movies, electronic news gathering (ENG) (including citizen journalism), and similar applications. Since the transition to digital video cameras, most cameras have in-built recording media and as such are also camcorders. Action cameras often have 360° recording capabilities.
Closed-circuit television (CCTV) generally uses pan tilt zoom cameras (PTZ), for security, surveillance, and/or monitoring purposes. Such cameras are designed to be small, easily hidden, and able to operate unattended; those used in industrial or scientific settings are often meant for use in environments that are normally inaccessible or uncomfortable for humans, and are therefore hardened for such hostile environments (e.g. radiation, high heat, or toxic chemical exposure).
Webcams are video cameras which stream a live video feed to a computer.
Many smartphones have built-in video cameras.
Special camera systems are used for scientific research, e.g. on board a satellite or a space probe, in artificial intelligence and robotics research, and in medical use. Such cameras are often tuned for non-visible radiation for infrared (for night vision and heat sensing) or X-ray (for medical and video astronomy use).Video camera tube
Video camera tubes were devices based on the cathode ray tube that were used to capture television images prior to the introduction of charge-coupled devices (CCDs) in the 1980s. Several different types of tubes were in use from the early 1930s to the 1980s.
In these tubes, the cathode ray was scanned across an image of the scene to be broadcast. The resultant current was dependent on the brightness of the image on the target. The size of the striking ray was tiny compared to the size of the target, allowing 483 horizontal scan lines per image in the NTSC format, or 576 lines in PAL.Viewing instrument
A viewing instrument is a device used for viewing or examining an object or scene, or some electrical property or signal. In some cases the thing viewed is mathematical. The names of many viewing instruments is derived from the English suffix -scope, meaning "see", which derives from the scientific Latin suffix -scopium, meaning a viewing instrument, which in turn originates from the ancient Greek verb skopein, meaning "to examine".Vladimir K. Zworykin
Vladimir Kosmich Zworykin (Russian: Влади́мир Козьми́ч Зворы́кин, Vladimir Koz'mich Zvorykin; July 29 [O.S. July 17] 1888 – July 29, 1982) was a Russian-born American inventor, engineer, and pioneer of television technology. Educated in Russia and in France, he spent most of his life in the United States. Zworykin invented a television transmitting and receiving system employing cathode ray tubes. He played a role in the practical development of television from the early thirties, including charge storage-type tubes, infrared image tubes and the electron microscope.
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