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139-422: Although the current technology emerged in the early-to-mid 1990s, fulldome environments have evolved from numerous influences, including immersive art and storytelling, with technological roots in domed architecture , planetariums , multi-projector film environments, flight simulation , and virtual reality . Initial approaches to moving fulldome imagery used wide-angle lenses , both 35mm and 70 mm film , but

278-585: A fisheye lens . Contemporary configurations employ raster video projectors , either singly or grouped together to cover the dome surface with full-color images and animations. Newer emerging technologies being utilized include flexible curved LED displays currently being installed at the fulldome MSG Sphere with assistance from Industrial Light and Magic . They are working together with 360-degree content creators to create feature-length fulldome content utilizing 360 degree cameras including Red Digital Cinema . Fulldome video projection can use

417-441: A phosphorescent screen. The images may represent electrical waveforms on an oscilloscope , a frame of video on an analog television set (TV), digital raster graphics on a computer monitor , or other phenomena like radar targets. A CRT in a TV is commonly called a picture tube . CRTs have also been used as memory devices , in which case the screen is not intended to be visible to an observer. The term cathode ray

556-512: A roof lantern and cupola. Domes have a long architectural lineage that extends back into prehistory . Domes were built in ancient Mesopotamia , and they have been found in Persian , Hellenistic , Roman , and Chinese architecture in the ancient world , as well as among a number of indigenous building traditions throughout the world. Dome structures were common in both Byzantine architecture and Sasanian architecture , which influenced that of

695-439: A video signal as a reference. In modern CRT monitors and TVs the beams are bent by magnetic deflection , using a deflection yoke . Electrostatic deflection is commonly used in oscilloscopes. The tube is a glass envelope which is heavy, fragile, and long from front screen face to rear end. Its interior must be close to a vacuum to prevent the emitted electrons from colliding with air molecules and scattering before they hit

834-419: A voltage multiplier for the current delivered by the flyback. For the inner funnel coating, monochrome CRTs use aluminum while color CRTs use aquadag ; Some CRTs may use iron oxide on the inside. On the outside, most CRTs (but not all) use aquadag. Aquadag is an electrically conductive graphite-based paint. In color CRTs, the aquadag is sprayed onto the interior of the funnel whereas historically aquadag

973-400: A " whispering gallery " at its base that at certain places transmits distinct sound to other distant places in the gallery. The half-domes over the apses of Byzantine churches helped to project the chants of the clergy. Although this can complement music, it may make speech less intelligible, leading Francesco Giorgi in 1535 to recommend vaulted ceilings for the choir areas of a church, but

1112-455: A CRT and limits its practical size (see § Size ). The funnel and neck glass comprise the remaining 30% and 5% respectively. The glass in the funnel can vary in thickness, to join the thin neck with the thick screen. Chemically or thermally tempered glass may be used to reduce the weight of the CRT glass. The outer conductive coating is connected to ground while the inner conductive coating

1251-472: A CRT as a display device. The Braun tube became the foundation of 20th century TV. In 1908, Alan Archibald Campbell-Swinton , fellow of the Royal Society (UK), published a letter in the scientific journal Nature , in which he described how "distant electric vision" could be achieved by using a cathode-ray tube (or "Braun" tube) as both a transmitting and receiving device. He expanded on his vision in

1390-406: A CRT can be measured by the screen's entire area (or face diagonal ) or alternatively by only its viewable area (or diagonal) that is coated by phosphor and surrounded by black edges. While the viewable area may be rectangular, the edges of the CRT may have a curvature (e.g. black stripe CRTs, first made by Toshiba in 1972) or the edges may be black and truly flat (e.g. Flatron CRTs), or

1529-515: A CRT is related to its screen size. Usual deflection angles were 90° for computer monitor CRTs and small CRTs and 110° which was the standard in larger TV CRTs, with 120 or 125° being used in slim CRTs made since 2001–2005 in an attempt to compete with LCD TVs. Over time, deflection angles increased as they became practical, from 50° in 1938 to 110° in 1959, and 125° in the 2000s. 140° deflection CRTs were researched but never commercialized, as convergence problems were never resolved. The size of

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1668-440: A CRT is usually made up of three parts: A screen/faceplate/panel, a cone/funnel, and a neck. The joined screen, funnel and neck are known as the bulb or envelope. The neck is made from a glass tube while the funnel and screen are made by pouring and then pressing glass into a mold. The glass, known as CRT glass or TV glass, needs special properties to shield against x-rays while providing adequate light transmission in

1807-426: A cathode in the rear of the CRT, causing it to emit electrons which are modulated and focused by electrodes. The electrons are steered by deflection coils or plates, and an anode accelerates them towards the phosphor -coated screen, which generates light when hit by the electrons. Cathode rays were discovered by Julius Plücker and Johann Wilhelm Hittorf . Hittorf observed that some unknown rays were emitted from

1946-480: A central point. The validity of this is unclear, as domes built underground with corbelled stone layers are in compression from the surrounding earth. The precise definition of "pendentive" has also been a source of academic contention, such as whether or not corbelling is permitted under the definition and whether or not the lower portions of a sail vault should be considered pendentives. Domes with pendentives can be divided into two kinds: simple and compound . In

2085-713: A circle . Because they reduce the portion of the dome in tension, these domes are strong but have increased radial thrust. Many of the largest existing domes are of this shape. Masonry saucer domes, because they exist entirely in compression, can be built much thinner than other dome shapes without becoming unstable. The trade-off between the proportionately increased horizontal thrust at their abutments and their decreased weight and quantity of materials may make them more economical, but they are more vulnerable to damage from movement in their supports. Also called gadrooned , fluted , organ-piped , pumpkin , melon , ribbed , parachute , scalloped , or lobed domes, these are

2224-554: A circular base alone, circular or polygonal base, circular, elliptical, or polygonal base, or an undefined area. Definitions specifying vertical sections include: semicircular, pointed, or bulbous; semicircular, segmental or pointed; semicircular, segmental, pointed, or bulbous; semicircular, segmental, elliptical, or bulbous; and high profile, hemispherical, or flattened. Sometimes called "false" domes, corbel domes achieve their shape by extending each horizontal layer of stones inward slightly farther than

2363-516: A circular base for a drum or compound dome, smoothly continue their curvature to form the dome itself. The dome gives the impression of a square sail pinned down at each corner and billowing upward. These can also be thought of as saucer domes upon pendentives. Sail domes are based upon the shape of a hemisphere and are not to be confused with elliptic parabolic vaults, which appear similar but have different characteristics. In addition to semicircular sail vaults there are variations in geometry such as

2502-495: A city." The French word dosme came to acquire the meaning of a cupola vault, specifically, by 1660. This French definition gradually became the standard usage of the English dome in the eighteenth century as many of the most impressive Houses of God were built with monumental domes, and in response to the scientific need for more technical terms. Across the ancient world, curved-roof structures that would today be called domes had

2641-526: A cross hatch pattern. CRT glass used to be made by dedicated companies such as AGC Inc. , O-I Glass , Samsung Corning Precision Materials, Corning Inc. , and Nippon Electric Glass ; others such as Videocon, Sony for the US market and Thomson made their own glass. The funnel and the neck are made of leaded potash-soda glass or lead silicate glass formulation to shield against x-rays generated by high voltage electrons as they decelerate after striking

2780-450: A dome has been a matter of controversy and there are a wide variety of forms and specialized terms to describe them. A dome can rest directly upon a rotunda wall, a drum , or a system of squinches or pendentives used to accommodate the transition in shape from a rectangular or square space to the round or polygonal base of the dome. The dome's apex may be closed or may be open in the form of an oculus , which may itself be covered with

2919-429: A dome. The top of a dome is the "crown". The inner side of a dome is called the "intrados" and the outer side is called the "extrados". As with arches, the "springing" of a dome is the base level from which the dome rises and the "haunch" is the part that lies roughly halfway between the base and the top. Domes can be supported by an elliptical or circular wall called a "drum". If this structure extends to ground level,

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3058-546: A flat ceiling filled with as many coffers as possible for where preaching would occur. Cavities in the form of jars built into the inner surface of a dome may serve to compensate for this interference by diffusing sound in all directions, eliminating echoes while creating a "divine effect in the atmosphere of worship." This technique was written about by Vitruvius in his Ten Books on Architecture , which describes bronze and earthenware resonators. The material, shape, contents, and placement of these cavity resonators determine

3197-538: A full dome. Another disadvantage of central projectors is the loss of the center of the dome for optimal viewing of the reconstructed perspective view provided by true hemispheric projection, a problem shared with traditional planetarium projectors. However, this disadvantage fades as audience size increases (everyone cannot be at the center of the dome anyway). Single-projector mirror systems, initially pioneered by Mirrordome at Swinburne University, are now offered by various manufacturers. These systems are positioned along

3336-402: A hemispherical dome can be 2.5 times thinner than a semicircular arch, and a dome with the profile of an equilateral arch can be thinner still. The optimal shape for a masonry dome of equal thickness provides for perfect compression, with none of the tension or bending forces against which masonry is weak. For a particular material, the optimal dome geometry is called the funicular surface ,

3475-509: A limited number of simple elements and joints and efficiently resolve a dome's internal forces. Their efficiency is said to increase with size. Although not first invented by Buckminster Fuller , they are associated with him because he designed many geodesic domes and patented them in the United States. The hemispherical dome is a surface formed by the rotation around a vertical axis of a semicircle . Like other "rotational domes" formed by

3614-513: A low rise to span ratio or covering a rectangular plan. Sail vaults of all types have a variety of thrust conditions along their borders, which can cause problems, but have been widely used from at least the sixteenth century. The second floor of the Llotja de la Seda is covered by a series of nine meter wide sail vaults. Also called segmental domes (a term sometimes also used for cloister vaults), or calottes , these have profiles of less than half

3753-600: A mainstay of display technology for decades, CRT-based computer monitors and TVs are now obsolete . Demand for CRT screens dropped in the late 2000s. Despite efforts from Samsung and LG to make CRTs competitive with their LCD and plasma counterparts, offering slimmer and cheaper models to compete with similarly sized and more expensive LCDs, CRTs eventually became obsolete and were relegated to developing markets and vintage enthusiasts once LCDs fell in price, with their lower bulk, weight and ability to be wall mounted coming as pluses. Some industries still use CRTs because it

3892-426: A metal funnel insulated with polyethylene instead of glass with conductive material. Others had ceramic or blown Pyrex instead of pressed glass funnels. Early CRTs did not have a dedicated anode cap connection; the funnel was the anode connection, so it was live during operation. The funnel is coated on the inside and outside with a conductive coating, making the funnel a capacitor, helping stabilize and filter

4031-437: A number of different names reflecting a variety of shapes, traditions, and symbolic associations. The shapes were derived from traditions of pre-historic shelters made from various impermanent pliable materials and were only later reproduced as vaulting in more durable materials. The hemispherical shape often associated with domes today derives from Greek geometry and Roman standardization, but other shapes persisted, including

4170-521: A pointed and bulbous tradition inherited by some early Islamic mosques. Modern academic study of the topic has been controversial and confused by inconsistent definitions, such as those for cloister vaults and domical vaults. Dictionary definitions of the term "dome" are often general and imprecise. Generally-speaking, it "is non-specific, a blanket-word to describe an hemispherical or similar spanning element." Published definitions include: hemispherical roofs alone; revolved arches ; and vaults on

4309-546: A powerful mortar. The aggregate transitioned over the centuries to pieces of fired clay, then to Roman bricks. By the sixth century, bricks with large amounts of mortar were the principle vaulting materials. Pozzolana appears to have only been used in central Italy. Brick domes were the favored choice for large-space monumental coverings until the Industrial Age , due to their convenience and dependability. Ties and chains of iron or wood could be used to resist stresses. In

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4448-522: A seamless image that covers a hemispherical projection surface; splitting the entire image up into segments allows for higher-resolution imagery and projector placement that does not intrude on the viewing area underneath the dome. A disadvantage of multiple projection is the need to frequently adjust the alignment of projectors and the uneven aging of separate projectors leading to brightness and color differences between segments. Even minor performance differences between projectors can be obvious when projecting

4587-464: A sheet of glass and the electrons were accelerated to a nearby sheet of glass with phosphors using an anode voltage. The electrons were not focused, making each subpixel essentially a flood beam CRT. They were never put into mass production as LCD technology was significantly cheaper, eliminating the market for such displays. The last large-scale manufacturer of (in this case, recycled) CRTs, Videocon , ceased in 2015. CRT TVs stopped being made around

4726-522: A short drum, as can be seen at the Shah Cheragh (1852–1853), first appeared in the Qajar period . Domes have remained important in modern mausoleums, and domed cisterns and icehouses remain common sights in the countryside. Cathode ray tube A cathode-ray tube ( CRT ) is a vacuum tube containing one or more electron guns , which emit electron beams that are manipulated to display images on

4865-421: A single (or mixed) video source displayed through a single fisheye lens , typically located at or near the center of a hemispherical projection surface. A single projector has the benefit of avoiding edge blends (see below) between multiple projectors. The main disadvantage of single fisheye systems is that they are limited to the resolution of one projector, and in the smallest dimension of the video image to cover

5004-450: A single arch or a set of multiple projecting nested arches placed diagonally over an internal corner. Squinch forms also include trumpet arches, niche heads (or half-domes), trumpet arches with "anteposed" arches, and muqarnas arches. Squinches transfer the weight of a dome across the gaps created by the corners and into the walls. Pendentives are triangular sections of a sphere, like concave spandrels between arches, and transition from

5143-549: A single point of origin. Their appearance in northern Russian architecture predates the Tatar occupation of Russia and so is not easily explained as the result of that influence. They became popular in the second half of the 15th century in the Low Countries of Northern Europe, possibly inspired by the finials of minarets in Egypt and Syria, and developed in the 16th and 17th centuries in

5282-576: A smaller diameter dome immediately above them, as in the Hagia Sophia, or a drum and dome, as in many Renaissance and post-Renaissance domes, with both forms resulting in greater height. One of the earliest types of ribbed vault, the first known examples are found in the Great Mosque of Córdoba in the 10th century. Rather than meeting in the center of the dome, the ribs characteristically intersect one another off-center, forming an empty polygonal space in

5421-484: A solid color across the entire scene. Edge blended areas where projectors overlap often have some smearing, double images, and can have very obvious additive black level areas if poorly designed or configured. A wide variety of video projection technologies has been employed in domes, including cathode ray tube (CRT), Digital Light Processing (DLP), liquid crystal display (LCD), liquid crystal on silicon (LCOS), and most recently, two varieties of laser projectors (see

5560-666: A speech given in London in 1911 and reported in The Times and the Journal of the Röntgen Society . The first cathode-ray tube to use a hot cathode was developed by John Bertrand Johnson (who gave his name to the term Johnson noise ) and Harry Weiner Weinhart of Western Electric , and became a commercial product in 1922. The introduction of hot cathodes allowed for lower acceleration anode voltages and higher electron beam currents, since

5699-444: A target, such as the phosphor screen or shadow mask of a color CRT. The velocity of the electrons depends on the anode voltage of the CRT; the higher the voltage, the higher the speed. The amount of x-rays emitted by a CRT can also lowered by reducing the brightness of the image. Leaded glass is used because it is inexpensive, while also shielding heavily against x-rays, although some funnels may also contain barium. The screen

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5838-531: A type of dome divided at the base into curved segments, which follow the curve of the elevation . "Fluted" may refer specifically to this pattern as an external feature, such as was common in Mamluk Egypt . The "ribs" of a dome are the radial lines of masonry that extend from the crown down to the springing. The central dome of the Hagia Sophia uses the ribbed method, which accommodates a ring of windows between

5977-433: A variety of technologies in two typical formats: single- and multiple-projector systems. The individual projector(s) can be driven by a variety of video sources, typically feeding material rendered in either real-time or pre-rendered modes. The result is a video image that covers an entire domed projection surface, yielding an immersive experience that fills a viewer's field of view. Single-projector fulldome video systems use

6116-542: A vertical axis of a semi-ellipse . Like other "rotational domes" formed by the rotation of a curve around a vertical axis, ellipsoidal domes have circular bases and horizontal sections and are a type of "circular dome" for that reason. Geodesic domes are the upper portion of geodesic spheres. They are composed of a framework of triangles in a polyhedron pattern. The structures are named for geodesics and are based upon geometric shapes such as icosahedrons , octahedrons or tetrahedrons . Such domes can be created using

6255-491: A very wide color space . DOME lenses and standard lens are similar in some ways. They both depend on the type of display device: LCD, DLP, LCOS, D-ILA, etc.; and the size chip or panel that is part of this device. The unique feature of the DOME lens is the actual shape of the glass, the projected image spill out from the top and all around the circumference of the lens. The biggest advantage is how this type of lens maintains focus over

6394-399: Is Avatar Flight of Passage . December: Houston Museum of Natural Science opens SkyVision system as a permanent public theater, with seed funding from NASA in partnership with Rice University . First playback fulldome show: "Cosmic Mysteries". Houston Museum of Natural Science premieres the first Earth Science fulldome show "Powers of Time" Carnegie Museum of Natural history opens

6533-455: Is a source of material for fulldome, that can be live simulator output, such as from planetarium simulation software, or prerecorded fulldome video. Live-Action FullDome videos are becoming more available for dome use as digital video camera resolutions increase. Real Time content can also be displayed, referring to fulldome content that is not pre-rendered and generated using VJ software or game engines . Notable films able to be displayed in

6672-776: Is called a Melon dome. A paraboloid dome is a surface formed by the rotation around a vertical axis of a sector of a parabola. Like other "rotational domes" formed by the rotation of a curve around a vertical axis, paraboloid domes have circular bases and horizontal sections and are a type of "circular dome" for that reason. Because of their shape, paraboloid domes experience only compression, both radially and horizontally. Also called sail vaults , handkerchief vaults , domical vaults (a term sometimes also applied to cloister vaults), pendentive domes (a term that has also been applied to compound domes), Bohemian vaults , or Byzantine domes , this type can be thought of as pendentives that, rather than merely touching each other to form

6811-440: Is connected using the anode button/cap through a series of capacitors and diodes (a Cockcroft–Walton generator ) to the high voltage flyback transformer ; the inner coating is the anode of the CRT, which, together with an electrode in the electron gun, is also known as the final anode. The inner coating is connected to the electrode using springs. The electrode forms part of a bipotential lens. The capacitors and diodes serve as

6950-677: Is either too much effort, downtime, and/or cost to replace them, or there is no substitute available; a notable example is the airline industry. Planes such as the Boeing 747-400 and the Airbus A320 used CRT instruments in their glass cockpits instead of mechanical instruments. Airlines such as Lufthansa still use CRT technology, which also uses floppy disks for navigation updates. They are also used in some military equipment for similar reasons. As of 2022 , at least one company manufactures new CRTs for these markets. A popular consumer usage of CRTs

7089-399: Is for retrogaming . Some games are impossible to play without CRT display hardware. Light guns only work on CRTs because they depend on the progressive timing properties of CRTs. Another reason people use CRTs due to the natural blending of these displays. Some games designed for CRT displays exploit this, which allows them to look more aesthetically pleasing on these displays. The body of

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7228-506: Is gradually reduced. This means that flat-screen CRTs may not be completely flat on the inside. The glass used in CRTs arrives from the glass factory to the CRT factory as either separate screens and funnels with fused necks, for Color CRTs, or as bulbs made up of a fused screen, funnel and neck. There were several glass formulations for different types of CRTs, that were classified using codes specific to each glass manufacturer. The compositions of

7367-401: Is made a complete and self-supporting ring. The upper portion of a masonry dome is always in compression and is supported laterally, so it does not collapse except as a whole unit and a range of deviations from the ideal in this shallow upper cap are equally stable. Because voussoir domes have lateral support, they can be made much thinner than corresponding arches of the same span. For example,

7506-477: Is not well documented. That the dome was known to early Mesopotamia may explain the existence of domes in both China and the West in the first millennium BC. Another explanation, however, is that the use of the dome shape in construction did not have a single point of origin and was common in virtually all cultures long before domes were constructed with enduring materials. Corbelled stone domes have been found from

7645-542: Is the igloo , a shelter built from blocks of compact snow and used by the Inuit , among others. The Himba people of Namibia construct "desert igloos" of wattle and daub for use as temporary shelters at seasonal cattle camps, and as permanent homes by the poor. Extraordinarily thin domes of sun-baked clay 20 feet in diameter, 30 feet high, and nearly parabolic in curve, are known from Cameroon . The historical development from structures like these to more sophisticated domes

7784-517: Is the first to have squinches create a regular octagon as a base for the dome, which then became the standard practice. Cylindrical or polygonal plan tower tombs with conical roofs over domes also exist beginning in the 11th century. The Seljuk Empire 's notables built tomb-towers, called "Turkish Triangles", as well as cube mausoleums covered with a variety of dome forms. Seljuk domes included conical, semi-circular, and pointed shapes in one or two shells. Shallow semi-circular domes are mainly found from

7923-419: Is usually instead made out of a special lead-free silicate glass formulation with barium and strontium to shield against x-rays, as it doesn't brown unlike glass containing lead. Another glass formulation uses 2–3% of lead on the screen. Alternatively zirconium can also be used on the screen in combination with barium, instead of lead. Monochrome CRTs may have a tinted barium-lead glass formulation in both

8062-471: The Aiken tube was invented. It was a CRT in a flat-panel display format with a single electron gun. Deflection was electrostatic and magnetic, but due to patent problems, it was never put into production. It was also envisioned as a head-up display in aircraft. By the time patent issues were solved, RCA had already invested heavily in conventional CRTs. 1968 marked the release of Sony Trinitron brand with

8201-484: The Middle East and Central Asia , domes and drums constructed from mud brick and baked brick were sometimes covered with brittle ceramic tiles on the exterior to protect against rain and snow. The new building materials of the 19th century and a better understanding of the forces within structures from the 20th century opened up new possibilities. Iron and steel beams, steel cables, and pre-stressed concrete eliminated

8340-625: The Neolithic period in the ancient Near East , and in the Middle East to Western Europe from antiquity. The kings of Achaemenid Persia held audiences and festivals in domical tents derived from the nomadic traditions of central Asia. Simple domical mausoleums existed in the Hellenistic period. The remains of a large domed circular hall in the Parthian capital city of Nyssa has been dated to perhaps

8479-513: The Safavid dynasty (1501–1732) are characterized by a distinctive bulbous profile and are considered the last generation of Persian domes. They are generally thinner than earlier domes and are decorated with a variety of colored glazed tiles and complex vegetal patterns, and they were influential on those of other Islamic styles, such as the Mughal architecture of India. An exaggerated style of onion dome on

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8618-470: The University of Kassel in 1983. A masonry dome produces thrusts downward and outward. They are thought of in terms of two kinds of forces at right angles from one another: meridional forces (like the meridians , or lines of longitude, on a globe) are compressive only, and increase towards the base, while hoop forces (like the lines of latitude on a globe) are in compression at the top and tension at

8757-486: The cathode (negative electrode) which could cast shadows on the glowing wall of the tube, indicating the rays were travelling in straight lines. In 1890, Arthur Schuster demonstrated cathode rays could be deflected by electric fields , and William Crookes showed they could be deflected by magnetic fields. In 1897, J. J. Thomson succeeded in measuring the mass-to-charge ratio of cathode rays, showing that they consisted of negatively charged particles smaller than atoms,

8896-467: The laser video projector ). For multi-projector systems, in particular, display devices must have a low black level (i.e., project little or no light when no signal is sent to them) to allow for reasonable edge-blending between the different projector footprints. Otherwise, overlapping video images will have an additive effect, causing a complex pattern of grey to appear even when no image is being projected. This becomes particularly important for users in

9035-482: The planetarium field, who have a vested interest in projecting a dark night sky. The desire for projectors to "go to black" has resulted in continued use of CRT technology, even as newer and less expensive technologies have emerged. LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetariums. LCOS and modified LCOS projectors have improved on LCD contrast ratios while also eliminating

9174-407: The "screen door" effect of small gaps between LCD pixels. "Dark chip" DLP projectors improve on the standard DLP design and can offer a relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors. As the technology matures and reduces in price, laser projection looks promising for dome projection as it offers bright images, large dynamic range and

9313-404: The 20th century have allowed for large dome-shaped structures that deviate from the traditional compressive structural behavior of masonry domes. Popular usage of the term has expanded to mean "almost any long-span roofing system". The word " cupola " is another word for "dome", and is usually used for a small dome upon a roof or turret . "Cupola" has also been used to describe the inner side of

9452-421: The CRT cathode wears out due to cathode poisoning before browning becomes apparent. The glass formulation determines the highest possible anode voltage and hence the maximum possible CRT screen size. For color, maximum voltages are often 24–32 kV, while for monochrome it is usually 21 or 24.5 kV, limiting the size of monochrome CRTs to 21 inches, or ~1 kV per inch. The voltage needed depends on

9591-461: The CRT. In 1954, RCA produced some of the first color CRTs, the 15GP22 CRTs used in the CT-100 , the first color TV set to be mass produced . The first rectangular color CRTs were also made in 1954. However, the first rectangular color CRTs to be offered to the public were made in 1963. One of the challenges that had to be solved to produce the rectangular color CRT was convergence at the corners of

9730-459: The CRT. In 1965, brighter rare earth phosphors began replacing dimmer and cadmium-containing red and green phosphors. Eventually blue phosphors were replaced as well. The size of CRTs increased over time, from 20 inches in 1938, to 21 inches in 1955, 25 inches by 1974, 30 inches by 1980, 35 inches by 1985, and 43 inches by 1989. However, experimental 31 inch CRTs were made as far back as 1938. In 1960,

9869-479: The Earth Theater with a SkyVision system November: Institute of American Indian Arts opens the world's first fully articulating digital dome. Dome A dome (from Latin domus ) is an architectural element similar to the hollow upper half of a sphere . There is significant overlap with the term cupola , which may also refer to a dome or a structure on top of a dome. The precise definition of

10008-575: The Fulldome format are Flesh and Sand by Academy Award winning director Alejandro González Iñárritu and three-time Academy Award-winning cinematographer Emmanuel Lubezki . The immersive film won a Special Achievement Academy Award by the Academy of Motion Picture Arts and Sciences . Another notable film able to be displayed in the Fulldome format is The Protectors from Academy Award-winning director Kathryn Bigelow . Other similar fulldome content

10147-629: The Netherlands before spreading to Germany, becoming a popular element of the baroque architecture of Central Europe. German bulbous domes were also influenced by Russian and Eastern European domes. The examples found in various European architectural styles are typically wooden. Examples include Kazan Church in Kolomenskoye and the Brighton Pavilion by John Nash . In Islamic architecture, they are typically made of masonry, rather than timber, with

10286-572: The Seljuk era. The double-shell domes were either discontinuous or continuous. The domed enclosure of the Jameh Mosque of Isfahan , built in 1086-7 by Nizam al-Mulk , was the largest masonry dome in the Islamic world at that time, had eight ribs, and introduced a new form of corner squinch with two quarter domes supporting a short barrel vault. In 1088 Tāj-al-Molk, a rival of Nizam al-Mulk, built another dome at

10425-588: The ancient Greek and Latin domus ("house"), which, up through the Renaissance, labeled a revered house, such as a Domus Dei , or "House of God", regardless of the shape of its roof. This is reflected in the uses of the Italian word duomo , the German/Icelandic/Danish word dom ("cathedral"), and the English word dome as late as 1656, when it meant a "Town-House, Guild-Hall, State-House, and Meeting-House in

10564-408: The anode now only accelerated the electrons emitted by the hot cathode, and no longer had to have a very high voltage to induce electron emission from the cold cathode. In 1926, Kenjiro Takayanagi demonstrated a CRT TV receiver with a mechanical video camera that received images with a 40-line resolution. By 1927, he improved the resolution to 100 lines, which was unrivaled until 1931. By 1928, he

10703-441: The anode voltage of the CRT, and significantly reducing the amount of time needed to turn on a CRT. The stability provided by the coating solved problems inherent to early power supply designs, as they used vacuum tubes. Because the funnel is used as a capacitor, the glass used in the funnel must be an excellent electrical insulator ( dielectric ). The inner coating has a positive voltage (the anode voltage that can be several kV) while

10842-424: The base, with the transition in a hemispherical dome occurring at an angle of 51.8 degrees from the top. The thrusts generated by a dome are directly proportional to the weight of its materials. Grounded hemispherical domes generate significant horizontal thrusts at their haunches. The outward thrusts in the lower portion of a hemispherical masonry dome can be counteracted with the use of chains incorporated around

10981-570: The case of the simple dome , the pendentives are part of the same sphere as the dome itself; however, such domes are rare. In the case of the more common compound dome , the pendentives are part of the surface of a larger sphere below that of the dome itself and form a circular base for either the dome or a drum section. The fields of engineering and architecture have lacked common language for domes, with engineering focused on structural behavior and architecture focused on form and symbolism. Additionally, new materials and structural systems in

11120-408: The center of the screen with a 546 nm wavelength light, and a 10.16mm thick screen. Transmittance goes down with increasing thickness. Standard transmittances for Color CRT screens are 86%, 73%, 57%, 46%, 42% and 30%. Lower transmittances are used to improve image contrast but they put more stress on the electron gun, requiring more power on the electron gun for a higher electron beam power to light

11259-463: The center. Geometry is a key element of the designs, with the octagon being perhaps the most popular shape used. Whether the arches are structural or purely decorative remains a matter of debate. The type may have an eastern origin, although the issue is also unsettled. Examples are found in Spain, North Africa, Armenia, Iran, France, and Italy. The ellipsoidal dome is a surface formed by the rotation around

11398-420: The centuries from mud, snow, stone, wood, brick, concrete, metal, glass, and plastic. The symbolism associated with domes includes mortuary , celestial , and governmental traditions that have likewise altered over time. The domes of the modern world can be found over religious buildings, legislative chambers, sports stadiums, and a variety of functional structures. The English word "dome" ultimately derives from

11537-508: The church of Santo Tomás de las Ollas in Spain has an oval dome over its oval plan. Other examples of medieval oval domes can be found covering rectangular bays in churches. Oval plan churches became a type in the Renaissance and popular in the Baroque style. The dome built for the basilica of Vicoforte by Francesco Gallo was one of the largest and most complex ever made. Although the ellipse

11676-501: The circle being considered the most perfect of forms. According to E. Baldwin Smith, from the late Stone Age the dome-shaped tomb was used as a reproduction of the ancestral, god-given shelter made permanent as a venerated home of the dead. The instinctive desire to do this resulted in widespread domical mortuary traditions across the ancient world, from the stupas of India to the tholos tombs of Iberia . By Hellenistic and Roman times,

11815-459: The circumference or with external buttressing, although cracking along the meridians is natural. For small or tall domes with less horizontal thrust, the thickness of the supporting arches or walls can be enough to resist deformation, which is why drums tend to be much thicker than the domes they support. Unlike voussoir arches, which require support for each element until the keystone is in place, domes are stable during construction as each level

11954-456: The comparable shape in three dimensions to a catenary curve for a two-dimensional arch. Adding a weight to the top of a pointed dome, such as the heavy cupola at the top of Florence Cathedral , changes the optimal shape to more closely match the actual pointed shape of the dome. The pointed profiles of many Gothic domes more closely approximate the optimal dome shape than do hemispheres, which were favored by Roman and Byzantine architects due to

12093-400: The corners of a square bay to the circular base of a dome. The curvature of the pendentives is that of a sphere with a diameter equal to the diagonal of the square bay. Pendentives concentrate the weight of a dome into the corners of the bay. The earliest domes in the Middle East were built with mud-brick and, eventually, with baked brick and stone. Domes of wood allowed for wide spans due to

12232-443: The dome's surface of revolution, or be straight lengths with the connecting points or nodes lying upon the surface of revolution. Single-layer structures are called frame or skeleton types and double-layer structures are truss types, which are used for large spans. When the covering also forms part of the structural system, it is called a stressed skin type. The formed surface type consists of sheets joined at bent edges to form

12371-538: The domical tholos had become the customary cemetery symbol. Domes and tent-canopies were also associated with the heavens in Ancient Persia and the Hellenistic-Roman world. A dome over a square base reflected the geometric symbolism of those shapes. The circle represented perfection, eternity, and the heavens. The square represented the earth. An octagon was intermediate between the two. The distinct symbolism of

12510-429: The early 2010s, CRTs have been superseded by flat-panel display technologies such as LCD , plasma display , and OLED displays which are cheaper to manufacture and run, as well as significantly lighter and thinner. Flat-panel displays can also be made in very large sizes whereas 40–45 inches (100–110 cm) was about the largest size of a CRT. A CRT works by electrically heating a tungsten coil which in turn heats

12649-523: The edge of the dome to enhance seating capacity, reduce costs, and facilitate the transition of analog planetariums to digital formats without sacrificing their star projectors. It is also possible to build such a system at relatively low cost. The main disadvantage is noticeably lower projection quality compared to purpose-built lenses, despite being able to project a higher proportion of the projector resolution. Multiple-projector fulldome video systems rely on two or more video projectors edge-blended to create

12788-475: The effect they have: reinforcing certain frequencies or absorbing them. Also called a corbelled dome , cribbed dome , or false dome , these are different from a 'true dome' in that they consist of purely horizontal layers. As the layers get higher, each is slightly cantilevered , or corbeled , toward the center until meeting at the top. A monumental example is the Mycenaean Treasury of Atreus from

12927-410: The expense and ungainly nature of the film medium prevented much progress; furthermore, film formats such as Omnimax did not cover the full two pi steradians of the dome surface, leaving a section of the dome blank (though, due to seating arrangements, that part of the dome was not seen by most viewers). Later approaches to fulldome utilized monochromatic vector graphics systems projected through

13066-499: The first " subatomic particles ", which had already been named electrons by Irish physicist George Johnstone Stoney in 1891. The earliest version of the CRT was known as the "Braun tube", invented by the German physicist Ferdinand Braun in 1897. It was a cold-cathode diode , a modification of the Crookes tube with a phosphor -coated screen. Braun was the first to conceive the use of

13205-651: The first CRT with HD resolution, the Sony KW-3600HD, was released to the market. It is considered to be "historical material" by Japan's national museum. The Sony KWP-5500HD, an HD CRT projection TV, was released in 1992. In the mid-1990s, some 160 million CRTs were made per year. In the mid-2000s, Canon and Sony presented the surface-conduction electron-emitter display and field-emission displays , respectively. They both were flat-panel displays that had one (SED) or several (FED) electron emitters per subpixel in place of electron guns. The electron emitters were placed on

13344-467: The first CRTs to last 1,000  hours of use, which was one of the factors that led to the widespread adoption of TV. The first commercially made electronic TV sets with cathode-ray tubes were manufactured by Telefunken in Germany in 1934. In 1947, the cathode-ray tube amusement device , the earliest known interactive electronic game as well as the first to incorporate a cathode-ray tube screen,

13483-466: The first century AD, showing "...the existence of a monumental domical tradition in Central Asia that had hitherto been unknown and which seems to have preceded Roman Imperial monuments or at least to have grown independently from them." It likely had a wooden dome. Persian architecture likely inherited an architectural tradition of dome-building dating back to the earliest Mesopotamian domes. Due to

13622-862: The first century BC, such as the Tabularium of Rome from 78 BC. Others include the Baths of Antoninus in Carthage (145–160) and the Palatine Chapel at Aachen (13th – 14th century). The most famous example is the Renaissance octagonal dome of Filippo Brunelleschi over the Florence Cathedral. Thomas Jefferson , the third president of the United States, installed an octagonal dome above the West front of his plantation house, Monticello . Also called domes on pendentives or pendentive domes (a term also applied to sail vaults), compound domes have pendentives that support

13761-611: The first examples in Asia Minor date to around 4000 B.C. The geometry was eventually defined using combinations of circular arcs, transitioning at points of tangency. If the Romans created oval domes, it was only in exceptional circumstances. The Roman foundations of the oval plan Church of St. Gereon in Cologne point to a possible example. Domes in the Middle Ages also tended to be circular, though

13900-463: The first manufacturers to stop CRT production was Hitachi in 2001, followed by Sony in Japan in 2004, Flat-panel displays dropped in price and started significantly displacing cathode-ray tubes in the 2000s. LCD monitor sales began exceeding those of CRTs in 2003–2004 and LCD TV sales started exceeding those of CRTs in some markets in 2005. Samsung SDI stopped CRT production in 2012. Despite being

14039-564: The forefront of Persian architecture as a result. Pre-Islamic domes in Persia are commonly semi-elliptical, with pointed domes and those with conical outer shells being the majority of the domes in the Islamic periods. The area of north-eastern Iran was, along with Egypt, one of two areas notable for early developments in Islamic domed mausoleums, which appear in the tenth century. The Samanid Mausoleum in Transoxiana dates to no later than 943 and

14178-533: The full 180 x 180 field of view. A single standard flat field or curved field lens would have major focus and distortion issue. Several lens developers offer DOME lenses with each designed to a specific projector class and a display device. These lenses can cover a variety of pixel sizes and display resolutions. 360-degree and 180-degree content creator filmmakers are developing more and more refined feature-length ready fulldome films and virtual reality content every year. And computer graphic (CG) content

14317-401: The furnace, to allow production of CRTs of several sizes. Only the glass used on the screen needs to have precise optical properties. The optical properties of the glass used on the screen affect color reproduction and purity in color CRTs. Transmittance, or how transparent the glass is, may be adjusted to be more transparent to certain colors (wavelengths) of light. Transmittance is measured at

14456-447: The heavenly or cosmic tent stemming from the royal audience tents of Achaemenid and Indian rulers was adopted by Roman rulers in imitation of Alexander the Great , becoming the imperial baldachin . This probably began with Nero , whose " Golden House " also made the dome a feature of palace architecture. The dual sepulchral and heavenly symbolism was adopted by early Christians in both

14595-482: The late Bronze Age . A single or double layer space frame in the form of a dome, a braced dome is a generic term that includes ribbed , Schwedler , three-way grid , lamella or Kiewitt , lattice , and geodesic domes . The different terms reflect different arrangements in the surface members. Braced domes often have a very low weight and are usually used to cover spans of up to 150 meters. Often prefabricated, their component members can either lie on

14734-411: The lower one until they meet at the top. A "false" dome may also refer to a wooden dome. The Italian use of the term finto , meaning "false", can be traced back to the 17th century in the use of vaulting made of reed mats and gypsum mortar. "True" domes are said to be those whose structure is in a state of compression, with constituent elements of wedge-shaped voussoirs , the joints of which align with

14873-489: The melts were also specific to each manufacturer. Those optimized for high color purity and contrast were doped with Neodymium, while those for monochrome CRTs were tinted to differing levels, depending on the formulation used and had transmittances of 42% or 30%. Purity is ensuring that the correct colors are activated (for example, ensuring that red is displayed uniformly across the screen) while convergence ensures that images are not distorted. Convergence may be modified using

15012-589: The model KV-1310, which was based on Aperture Grille technology. It was acclaimed to have improved the output brightness. The Trinitron screen was identical with its upright cylindrical shape due to its unique triple cathode single gun construction. In 1987, flat-screen CRTs were developed by Zenith for computer monitors, reducing reflections and helping increase image contrast and brightness. Such CRTs were expensive, which limited their use to computer monitors. Attempts were made to produce flat-screen CRTs using inexpensive and widely available float glass . In 1990,

15151-449: The need for external buttressing and enabled much thinner domes. Whereas earlier masonry domes may have had a radius to thickness ratio of 50, the ratio for modern domes can be in excess of 800. The lighter weight of these domes not only permitted far greater spans, but also allowed for the creation of large movable domes over modern sports stadiums. Experimental rammed earth domes were made as part of work on sustainable architecture at

15290-675: The opposite end of the same mosque with interlacing ribs forming five-pointed stars and pentagons. This is considered the landmark Seljuk dome, and may have inspired subsequent patterning and the domes of the Il-Khanate period. The use of tile and of plain or painted plaster to decorate dome interiors, rather than brick, increased under the Seljuks. Beginning in the Ilkhanate , Persian domes achieved their final configuration of structural supports, zone of transition, drum, and shells, and subsequent evolution

15429-530: The outer coating is connected to ground. CRTs powered by more modern power supplies do not need to be connected to ground , due to the more robust design of modern power supplies. The value of the capacitor formed by the funnel is 5–10  nF , although at the voltage the anode is normally supplied with. The capacitor formed by the funnel can also suffer from dielectric absorption , similarly to other types of capacitors. Because of this CRTs have to be discharged before handling to prevent injury. The depth of

15568-443: The phosphors more brightly to compensate for the reduced transmittance. The transmittance must be uniform across the screen to ensure color purity. The radius (curvature) of screens has increased (grown less curved) over time, from 30 to 68 inches, ultimately evolving into completely flat screens, reducing reflections. The thickness of both curved and flat screens gradually increases from the center outwards, and with it, transmittance

15707-581: The place of a prince during royal ceremonies. Over time such domes became primarily focal points for decoration or the direction of prayer. The use of domes in mausoleums can likewise reflect royal patronage or be seen as representing the honor and prestige that domes symbolized, rather than having any specific funerary meaning. The wide variety of dome forms in medieval Islam reflected dynastic, religious, and social differences as much as practical building considerations. Because domes are concave from below, they can reflect sound and create echoes. A dome may have

15846-458: The relatively light and flexible nature of the material and were the normal method for domed churches by the 7th century, although most domes were built with the other less flexible materials. Wooden domes were protected from the weather by roofing, such as copper or lead sheeting. Domes of cut stone were more expensive and never as large, and timber was used for large spans where brick was unavailable. Roman concrete used an aggregate of stone with

15985-555: The rest of Europe and Islam , respectively, in the Middle Ages . The domes of European Renaissance architecture spread from Italy in the early modern period , while domes were frequently employed in Ottoman architecture at the same time. Baroque and Neoclassical architecture took inspiration from Roman domes. Advancements in mathematics, materials, and production techniques resulted in new dome types. Domes have been constructed over

16124-417: The ribs at the base of the dome. The central dome of St. Peter's Basilica also uses this method. Cultures from pre-history to modern times constructed domed dwellings using local materials. Although it is not known when the first dome was created, sporadic examples of early domed structures have been discovered. The earliest discovered may be four small dwellings made of Mammoth tusks and bones. The first

16263-471: The rotation of a curve around a vertical axis, hemispherical domes have circular bases and horizontal sections and are a type of "circular dome" for that reason. They experience vertical compression along their meridians, but horizontally experience compression only in the portion above 51.8 degrees from the top. Below this point, hemispherical domes experience tension horizontally, and usually require buttressing to counteract it. According to E. Baldwin Smith, it

16402-402: The round building may be called a " rotunda ". Drums are also called " tholobates " and may or may not contain windows. A " tambour " or " lantern " is the equivalent structure over a dome's oculus, supporting a cupola. When the base of the dome does not match the plan of the supporting walls beneath it (for example, a dome's circular base over a square bay ), techniques are employed to bridge

16541-674: The same time. In 2012, Samsung SDI and several other major companies were fined by the European Commission for price fixing of TV cathode-ray tubes. The same occurred in 2015 in the US and in Canada in 2018. Worldwide sales of CRT computer monitors peaked in 2000, at 90 million units, while those of CRT TVs peaked in 2005 at 130 million units. Beginning in the late 1990s to the early 2000s, CRTs began to be replaced with LCDs, starting first with computer monitors smaller than 15 inches in size, largely because of their lower bulk. Among

16680-490: The scarcity of wood in many areas of the Iranian plateau and Greater Iran , domes were an important part of vernacular architecture throughout Persian history. The Persian invention of the squinch , a series of concentric arches forming a half-cone over the corner of a room, enabled the transition from the walls of a square chamber to an octagonal base for a dome in a way reliable enough for large constructions and domes moved to

16819-406: The screen and funnel, with a potash-soda lead glass in the neck; the potash-soda and barium-lead formulations have different thermal expansion coefficients. The glass used in the neck must be an excellent electrical insulator to contain the voltages used in the electron optics of the electron gun, such as focusing lenses. The lead in the glass causes it to brown (darken) with use due to x-rays, usually

16958-427: The screen may contain 12% of barium oxide , and 12% of strontium oxide . A typical CRT contains several kilograms of lead as lead oxide in the glass depending on its size; 12 inch CRTs contain 0.5 kg of lead in total while 32 inch CRTs contain up to 3 kg. Strontium oxide began being used in CRTs, its major application, in the 1970s. Before this, CRTs used lead on the faceplate. Some early CRTs used

17097-449: The screen or being very electrically insulating in the funnel and neck. The formulation that gives the glass its properties is also known as the melt. The glass is of very high quality, being almost contaminant and defect free. Most of the costs associated with glass production come from the energy used to melt the raw materials into glass. Glass furnaces for CRT glass production have several taps to allow molds to be replaced without stopping

17236-444: The size and type of CRT. Since the formulations are different, they must be compatible with one another, having similar thermal expansion coefficients. The screen may also have an anti-glare or anti-reflective coating, or be ground to prevent reflections. CRTs may also have an anti-static coating. The leaded glass in the funnels of CRTs may contain 21–25% of lead oxide (PbO), The neck may contain 30–40% of lead oxide, and

17375-465: The structure. Also called domical vaults (a term sometimes also applied to sail vaults), polygonal domes , coved domes , gored domes , segmental domes (a term sometimes also used for saucer domes), paneled vaults , or pavilion vaults , these are domes that maintain a polygonal shape in their horizontal cross section. The component curved surfaces of these vaults are called severies , webs , or cells . The earliest known examples date to

17514-453: The thick and heavy bulging portion serving to buttress against the tendency of masonry domes to spread at their bases. The Taj Mahal is a famous example. An oval dome is a dome of oval shape in plan, profile, or both. The term comes from the Latin ovum , meaning "egg". The earliest oval domes were used by convenience in corbelled stone huts as rounded but geometrically undefined coverings, and

17653-436: The tube's face. Thus, the interior is evacuated to less than a millionth of atmospheric pressure . As such, handling a CRT carries the risk of violent implosion that can hurl glass at great velocity. The face is typically made of thick lead glass or special barium - strontium glass to be shatter-resistant and to block most X-ray emissions. This tube makes up most of the weight of CRT TVs and computer monitors. Since

17792-544: The two shells of the dome have significantly different profiles, which spread rapidly throughout the region. The development of taller drums also continued into the Timurid period. The large, bulbous, fluted domes on tall drums that are characteristic of 15th century Timurid architecture were the culmination of the Central Asian and Iranian tradition of tall domes with glazed tile coverings in blue and other colors. The domes of

17931-505: The two. One technique is to use corbelling, progressively projecting horizontal layers from the top of the supporting wall to the base of the dome, such as the corbelled triangles often used in Seljuk and Ottoman architecture. The simplest technique is to use diagonal lintels across the corners of the walls to create an octagonal base. Another is to use arches to span the corners, which can support more weight. A variety of these techniques use what are called " squinches ". A squinch can be

18070-477: The use of domes in architecture and in the ciborium , a domical canopy like the baldachin used as a ritual covering for relics or the church altar . The celestial symbolism of the dome, however, was the preeminent one by the Christian era . In the early centuries of Islam, domes were closely associated with royalty. A dome built in front of the mihrab of a mosque, for example, was at least initially meant to emphasize

18209-457: The viewable area may follow the curvature of the edges of the CRT (with or without black edges or curved edges). Small CRTs below 3 inches were made for handheld TVs such as the MTV-1 and viewfinders in camcorders. In these, there may be no black edges, that are however truly flat. Most of the weight of a CRT comes from the thick glass screen, which comprises 65% of the total weight of

18348-515: Was a shape likely known to the Assyrians, defined by Greek theoretical mathematicians, and standardized by Roman builders. Bulbous domes bulge out beyond their base diameters, offering a profile greater than a hemisphere. An onion dome is a greater than hemispherical dome with a pointed top in an ogee profile. They are found in the Near East , Middle East , Persia, and India and may not have had

18487-421: Was created. From 1949 to the early 1960s, there was a shift from circular CRTs to rectangular CRTs, although the first rectangular CRTs were made in 1938 by Telefunken. While circular CRTs were the norm, European TV sets often blocked portions of the screen to make it appear somewhat rectangular while American sets often left the entire front of the CRT exposed or only blocked the upper and lower portions of

18626-579: Was found by a farmer in Mezhirich , Ukraine, in 1965 while he was digging in his cellar and archaeologists unearthed three more. They date from 19,280 – 11,700 BC. In modern times , the creation of relatively simple dome-like structures has been documented among various indigenous peoples around the world. The wigwam was made by Native Americans using arched branches or poles covered with grass or hides. The Efé people of central Africa construct similar structures , using leaves as shingles. Another example

18765-512: Was known, in practice, domes of this shape were created by combining segments of circles. Popular in the 16th and 17th centuries, oval and elliptical plan domes can vary their dimensions in three axes or two axes. A sub-type with the long axis having a semicircular section is called a Murcia dome, as in the Chapel of the Junterones at Murcia Cathedral . When the short axis has a semicircular section, it

18904-428: Was painted into the interior of monochrome CRTs. The anode is used to accelerate the electrons towards the screen and also collects the secondary electrons that are emitted by the phosphor particles in the vacuum of the CRT. The anode cap connection in modern CRTs must be able to handle up to 55–60kV depending on the size and brightness of the CRT. Higher voltages allow for larger CRTs, higher image brightness, or

19043-405: Was restricted to variations in form and shell geometry. Characteristic of these domes are the use of high drums and several types of discontinuous double-shells, and the development of triple-shells and internal stiffeners occurred at this time. The construction of tomb towers decreased. The 7.5 meter wide double dome of Soltan Bakht Agha Mausoleum (1351–1352) is the earliest known example in which

19182-425: Was the first to transmit human faces in half-tones on a CRT display. In 1927, Philo Farnsworth created a TV prototype. The CRT was named in 1929 by inventor Vladimir K. Zworykin . He was subsequently hired by RCA , which was granted a trademark for the term "Kinescope", RCA's term for a CRT, in 1932; it voluntarily released the term to the public domain in 1950. In the 1930s, Allen B. DuMont made

19321-475: Was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons. In CRT TVs and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster . In color devices, an image is produced by controlling the intensity of each of three electron beams , one for each additive primary color (red, green, and blue) with

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