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Movie Theater

Movie theater

Ontario Mills 30 in Ontario, California).]] A movie theater or cinema is a location, usually a building, for viewing movies. Colloquial expressions, mostly used for cinemas collectively, include the silver screen and the big screen (contrasted with the "small screen" of television). Generally, theaters are not owned by individuals, but rather operated by corporations and visited by the general public: one can attend the film showing after buying a ticket. The film is projected with a movie projector onto a large projection screen at the front of the auditorium.

Design

projection screen, wall-mounted speakers, and cup holders.]] Traditionally a movie theater, like a stage theater, consists of a single auditorium with rows of comfortable seats, as well as a lobby area containing a box office, refreshment facilities, and washrooms. Stage theaters are sometimes converted into movie theaters by placing a screen in front of the stage and adding a projector; this conversion may be permanent, or temporary for purposes such as showing art house fare to an audience accustomed to plays. The familiar characteristics of relatively low admission and open seating can be traced to Samuel "Roxy" Rothapfel, an early movie theatre architect. Many of these early theaters contain a balcony, an elevated platform above the theaters rearmost seats. The rearward main floor "loge" seats were sometimes larger, softer, and more widely spaced and sold for a higher price. The first permanent structure designed for screening of movies was Tally's Electric Theater, completed in 1902 in Los Angeles, California. The 1913 opening of the Regent Theater in New York City signalled a new respectability for the medium, and the start of the two-decade heyday of American cinema design. Los Angeles promoter Sid Grauman began the trend of theatre-as-destination with his ornate "Million Dollar Theatre", which opened on Broadway in downtown Los Angeles in 1918. In the next ten years, as movie revenues exploded, independent promoters and movie studios (who owned their own proprietary chains until an antitrust ruling in 1948) raced to build the most lavish, elaborate, attractive theatres. These forms morphed into a unique architectural genre—the movie palace—a unique and extreme architectural genre which came to an end with the deepening of the Great Depression. The movie chains were also among the first industries to install to a large extent air conditioning systems which gave the theatres an addition lure of comfort in the summer period. In conventional low pitch viewing floors the preferred seating arrangement is to use staggered rows. While a less efficient use of floor space this allows a somewhat improved sight line between the patrons seated in the next row toward the screen, provided they do not lean toward one another. So-called "stadium seating" is employed in many modern theaters. Originally employed for flat-screen IMAX viewing (which has a very tall screen) this feature has proven popular with theater patrons as it allows a clear sight line over the seated occupants forward of the viewer. Several movie studios achieved vertical integration by acquiring and constructing theater chains. The so-called "Big Five" theater chains of the 1920s and 1930s were all owned by studios: Paramount, Warner, Loews (owned by Metro-Goldwyn-Mayer), Fox, and RKO. All were broken up as a result of the U.S. Supreme Court's ruling in the 1948 United States v. Paramount Pictures, Inc. anti-trust case. Since the mid-1960s in many areas the traditional theater has been largely replaced by multiplex cinemas, where a single lobby is shared between several auditoriums (the term "cinema" or "theater" may then mean either the whole complex or a single auditorium; sometimes "screen" is used with the latter meaning). This arrangement allows the operating company to show more movies with fewer staff. Sometimes a popular movie is shown on multiple screens at the same multiplex, reducing the choice of movies but offering more choice of viewing times. Two or three screens may be produced by dividing up an existing cinema, but newly built multiplexes usually have at least 6 to 8 screens. A very large, modern multiplex with 15 or more screens is called a megaplex. AMC Theatres is credited with creating the first multiplex; Kinepolis pioneered the first megaplex. IMAX is a system using oversized film to produce image quality far superior to conventional film. IMAX theaters require an oversized screen as well as special projectors. The first permanent IMAX theater was at Ontario Place in Toronto, Canada. Some movie theaters are outdoors and so can only be used when it is dark. A drive-in movie theater is basically a parking area with a screen at one end and a projection booth at the other. Moviegoers drive into the parking spaces which are usually provided with portable loudspeakers or the vehicle's sound system tunes to an FM station over which the soundtrack is played, and the movie is viewed through the car windscreen. Drive-in movies were mainly found in the United States, and were especially popular in the 1950s and 1960s, but are now almost extinct. Some outdoor movie theaters are just cleared areas where the audience sits upon chairs or blankets and watch the movie on a temporary screen, or even the wall of a convenient building. In the late 1990s, student organisations in universities and schools started to show movies in auditoriums equipped with multimedia projectors. Before the ubiquity of classic and modern films in DVD and VHS formats, student groups at large universities often sponsored screenings of films on 16mm projectors in lecture halls as a way to raise money. Many small colleges also had student-run film groups that projected 16mm films on a regular basis to students. Some alternative methods of showing movies have been popular in the past. In the 1980s the introduction of VHS cassettes made possible video-salons, small rooms where visitors viewed the film on a large TV. These establishments were especially popular in the Soviet Union, where official distribution companies were slow to adapt to changing demand and so movie theaters could not show popular Hollywood and Asian films. Movies are also commonly shown on airliners in flight, using large screens in each cabin or smaller screens for each group of rows or each individual seat; the airline company sometimes charges a fee for the headphones needed to hear the movie's sound. Movies can also be shown on trains.

Programming

Movie theaters may also be classified by the type of movies shown:
- First-run theater: A theater that runs primarily mainstream film fare from the major film companies and distributors, during the initial release period of each film.
- Second-run or discount theater: A theater that runs films that have been pulled from the first-run theaters and presented at a lower ticket price.
- Repertoire/repertory theater or art house: A theater that presents more alternative and art films as well as second-run and classic films. (These are sometimes known as dollar theaters.)
- A sex theater specializes in showing pornographic movies.
- IMAX theaters can show conventional movies, but the major benefits of the IMAX system are only available when showing movies filmed using it. While a few mainstream feature films have been produced in IMAX, IMAX movies are often documentaries featuring spectacular natural scenery, and may be limited to the 45-minute length of a single reel of IMAX film.

Break

There are the following alternatives:
- no break
- the screening of the feature film is interrupted by a break
- there is a break after the introductory program of e.g. short subjects, trailers and/or other commercials, before the feature film.
- a double feature with a break between the two movies.

Admission

According to motion picture rating systems, children or teenagers below a certain age may be forbidden access to theaters showing certain movies, or simply subject to parental guidance. The price of a ticket may be higher at busy times, typically evenings and/or weekends. Some movie theatre chains sell passes for unlimited entrance. For example, for the chain of 12 multi- and megaplex theatres of Pathé in the Netherlands, for 17.50 euro/month.

Crowd control

As movie theaters have grown into multiplexes and megaplexes, crowd control has become a major concern. An overcrowded megaplex can be rather unpleasant, and in an emergency can be extremely dangerous. Therefore, all major theater chains have implemented crowd control measures. The most well-known measure is the ubiquitous holdout line which prevents ticketholders for the next showing of that weekend's most popular movie from entering the building until their particular auditorium has been cleared out and cleaned. Since the 1980s, some theater chains (especially AMC Theatres) have developed a policy of co-locating their theaters in shopping centers (as opposed to the old practice of building stand-alone theaters). They deliberately build lobbies and corridors that cannot hold as many people as the auditoriums, thus making holdout lines necessary. In turn, ticketholders may be enticed to shop or eat while stuck outside in the holdout line.

"The back row"

Sometimes couples go to a movie theater for the additional reason that it provides the possibility of some physical intimacy, where the dark provides some privacy (with additional privacy in the back-row). This applies in particular for young people who still live with their parents, and these parents tend to monitor and/or forbid certain activities. Compared with being together in a room without other people, it may also be reassuring for one or both of the couple (and for parents) that the intimacy is necessarily limited. Arm rests may be a hindrance for intimacy. Some theaters have love seats: seats for two without an armrest in the middle. The most modern theaters have movable armrests throughout the theater that when down can hold a food container as well as act as an armrest or partition between the seats and when up allow closer contact between the couple. More expensive theaters may have large comfortable sofas.

Other services

Movie theaters usually sell various snack foods and drinks at concession stands which often represents their primary source of income; movie studios in the U.S. traditionally drive hard bargains entitling them to more than 70, 80, or 90% of the gross ticket revenue during the first week (and then the balance changes in 10% increments per week from there). Some movie theaters forbid eating and drinking inside the viewing room (restricting such activities to the lobby), while others encourage it, e.g. by selling large portions of popcorn; however, also in that case bringing one's own food and drinks may be forbidden. Concessions is currently a huge area of expansion with many companies in the U.S. offering a wider range of snacks, including hot dogs and nachos. The noise of people eating, including the opening of wrappers, is frowned upon by many moviegoers. It is quite common for the lobby to include an arcade game area.

Business practice controversies

A recent development in cinema programming has been the inclusion of commercial advertising shorts that have nothing to do with film. Many filmgoers have complained that these advertisements defeat the basic point of the experience of seeing films without this kind of commercialism interfering. Other critics such as Roger Ebert have expressed concerns that these advertisement, plus an excessive number of movie trailers could lead to pressure to restrict the preferred length of the feature films themselves to facilitate playing schedules. So far, the theatre companies have typically been highly resistant to these complaints, citing the need for the supplementary income. Some chains like Famous Players have compromised with the commercials restricted to being shown before the scheduled start time for the trailers and the feature film. Another major recent concern is that the dramatic improvements in stereo sound systems have led to cinemas playing the soundtracks of presented films at unacceptably high volume levels. Usually, the trailers are presented at a very high sound level, presumably to overcome the sounds of a busy crowd. The sound is not adjusted downward for a sparsely occupied theater, and some patrons employ earplugs for the trailer period. In recent years cinemas have started to show warnings, before the movie starts, against using cameras and camcorders during the movie. These warnings threaten customers with being removed from the cinema and arrest by the police. This example was shown at cinemas in the United Kingdom: : You are not permitted to use any camera or recording equipment in this cinema. This will be treated as an attempt to breach copyright. Any person doing so can be ejected and such articles may be confiscated by the police. We ask the audience to be vigilant against any such activity and report any matters arousing suspicion to cinema staff. Thank you. The multiplex offers a great amount of flexibility to a theater operator, enabling multiple theaters to exhibit the same popular production in multiple theaters with staggered starting times. The colocation of theaters and the rotation of start times results in a great economy of scale for the sale of so-called "junk food" — sugary soda pop, popcorn, and the like. In addition to poor nutritional values, the foodstuffs sold are also characterised by extremely high markup and the profit from their sales can form the bulk of the gross margin of a theater.

Major movie theater companies

North America

- AMC Theatres - 450 theatres - North America's second-largest movie theater chain (usually the industry leader in profitability)
- Carmike Cinemas
- Century Theatres- over 1000 screens
- Cinemark Theatres
- Cinémas Guzzo - As of 2005, thirteen locations in the Montreal area
- Cineplex Odeon Corporation
- Coming Attractions - As of July 2005, thirteen locations in California, Oregon, and Washington state
- Consolidated Theatres - A Charlotte, North Carolina-based chain that serves several mid-Atlantic states
- Eastern Federal Theatres- Small chain of theatres in central North Carolina that was recently bought out by Regal.
- Empire Theatres - 59 locations, 403 screens - Leading chain of movie theaters in the Atlantic Canadian provinces
- Famous Players - Formerly Canada's largest theater chain, bought by Cineplex Odeon in 2005
- Galaxy Theatres
- Goodrich Quality Theaters - over 35 movie theaters
- Kerasotes Theatres - 76 theatres with 607 screens, in the upper Midwest
- Landmark Theatres - 58 theatres, 209 screens
- Loews Cineplex Entertainment - 200 theaters, 2,176 screens
- Mann Theatres - 20 theatres, 122 screens in Southern California
- Marcus Theatres
- Marquee Cinemas - A fairly small movie theater chain, operated out of Beckley, West Virginia
- Muvico Theaters - United States chain based in Ft. Lauderdale, Florida
- National Amusements - 1,300 screens - Parent company of Viacom
- Rainbow and Magic Lantern Cinemas
- Regal Entertainment Group - 584 locations, 6,273 screens - North America's largest movie theater chain. Includes Edwards Cinemas, Regal Theaters, and United Artists
- Rave Motion Pictures - A fairly small, new, futuristic movie theater chain.

Ontario, California

]Ontario is a city located in San Bernardino County, California. As of the 2000 census, the city had a total population of 158,007. It is the home of Ontario International Airport and the huge Ontario Mills shopping mall (the largest in the Inland Empire and one of the largest in North America). It is also the former home of the Ontario Motor Speedway. It takes its name from the Ontario Model Colony development established in 1882 by Canadian engineers George Chaffey and William Chaffey, who named the settlement after their home province of Ontario, Canada.

History

The area that is now Ontario was probably part of the lands used for hunting and foraging by the nomadic Tongva (Gabrieleño) Indians, who came to the region in about 500 BCE. Juan Bautista de Anza is said to have passed through the area on his 1774 expedition, and to this day a city park and an elementary school bear his name. Following the 1819 establishment of San Bernardino Asistencia, which served as an outpost of the San Gabriel mission, it became part of a large, vaguely identified area called "San Antonio". The 1834 secularization of California land holdings resulted in the land's transferral to private hands. In 1881, the Chaffey brothers purchased the land (which at that time also included the present-day city of Upland) and the water rights to it. They engineered a drainage system channeling water from the foothills of Mount Baldy down to the flatter lands below that performed the dual functions of allowing farmers to water their crops and preventing the floods that periodically afflict them. They also created the main thoroughfare of Euclid Avenue (California Highway 83), with its distinctive wide lanes and grassy median. The new "Model Colony" (called so because it offered the perfect balance between agriculture and the urban comforts of schools and churches) was originally conceived as a dry town, but attracted (primarily citrus) farmers and ailing Easterners seeking a drier climate. A impress visitors and potential settlers with the "abundance" of water in Ontario, a fountain was placed at the Southern Pacific railway station, where it was set to turn on once an hour--just at the moment the train arrived. Today the fountain is located outside the Ontario Museum of History and Art. Agriculture was vital to the early economy, and many street names recall this legacy. The Sunkist plant also remains as a living vestige of the citrus era. The Chaffey brothers left to found the settlement of Mildura, Australia, which was not as successful. Charles Frankish continued their work, and was instrumental in the 1887 creation of the mule cart, which travelled up Euclid Avenue to 24th street and allowed the mule to ride on the way down. No longer in use, the mule cart is commemorated with an enclosed statue south of C Street on the Euclid median. Ontario was incorporated as a city in 1891, and North Ontario broke away in 1910, calling itself Upland.

Geography

Ontario is located at 34°3'10" North, 117°37'40" West (34.052811, -117.627861). According to the United States Census Bureau, the city has a total area of 129.1 km² (49.9 mi²). Of that, 128.9 km² (49.8 mi²) is land and 0.2 km² (0.1 mi²) is water. The total area is 0.14% water.

Demographics

As of the census of 2000, there are 158,007 people, 43,525 households, and 34,689 families residing in the city. The population density is 1,225.5/km² (3,173.9/mi²). There are 45,182 housing units at an average density of 350.4/km² (907.6/mi²). The racial makeup of the city is 30.83% White, 0.51% African American, 0.06% Native American, 3.88% Asian, 0.37% Pacific Islander, 47.00% Hispanic. There are 43,525 households out of which 49.4% have children under the age of 18 living with them, 56.9% are married couples living together, 15.5% have a female householder with no husband present, and 20.3% are non-families. 15.1% of all households are made up of individuals and 4.6% have someone living alone who is 65 years of age or older. The average household size is 3.60 and the average family size is 3.96. In the city the population is spread out with 34.4% under the age of 18, 11.2% from 18 to 24, 32.4% from 25 to 44, 16.1% from 45 to 64, and 5.9% who are 65 years of age or older. The median age is 28 years. For every 100 females there are 100.6 males. For every 100 females age 18 and over, there are 98.7 males. The median income for a household in the city is $42,452, and the median income for a family is $44,031. Males have a median income of $31,664 versus $26,069 for females. The per capita income for the city is $14,244. 15.5% of the population and 12.2% of families are below the poverty line. Out of the total population, 19.1% of those under the age of 18 and 7.6% of those 65 and older are living below the poverty line.

Law enforcement/crime

Ontario is well-known for the infamous OVS Black Angels gang that has engaged in countless incidents of gang violence since the 1950s. In response, the Ontario Police Department has become somewhat well-known for its attempts in keeping the city's gang problem under control.

Famous people from or residing in Ontario

- Del Crandall
- Landon Donovan
- Anthony Muñoz

External links

- [http://www.ci.ontario.ca.us Official site] Category:Cities in San Bernardino County Category:Boomburbs

Television

: Television is a telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term has come to refer to all the aspects of television programming and transmission as well. programming ]]

History

The development of television technology can be partitioned along two lines: those developments that depended upon both mechanical and electronic principles, and those which are purely electronic. From the latter descended all modern televisions, but these would not have been possible without discoveries and insights from the mechanical systems. The word television is a hybrid word, created from both Greek and Latin. Tele- is Greek for "far", while -vision is from the Latin visio, meaning "vision" or "sight". It is often abbreviated as TV or the telly.

Electromechanical television

The German student Paul Gottlieb Nipkow proposed and patented the first electromechanical television system in 1885. Nipkow's spinning disk design is credited with being the first television image rasterizer. However, it wasn't until 1907 that developments in amplification tube technology made the design practical. Meanwhile, Constantin Perskyi had coined the word television in a paper read to the International Electricity Congress at the International World Fair in Paris on August 25, 1900. Perskeyi's paper reviewed the existing electromechanical technologies, mentioning the work of Nipkow and others. 1900 In 1911, Boris Rosing and his student Vladimir Kosma Zworykin achieved a television system that used a mechanical mirror-drum scanner to transmit, in Zworykin's words, "very crude images" over wires to the electronic Braun tube (cathode ray tube) in the receiver. Moving images were not possible because, in the scanner, "the sensitivity was not enough and the selenium cell was very laggy." Zworykin later went to work for RCA to build a purely electronic television, the design of which was eventually found to violate patents by Philo Taylor Farnsworth. On March 25, 1925, Scottish inventor John Logie Baird gave a demonstration of televised silhouette images at Selfridge's Department Store in London. But if television is defined as the transmission of live, moving, half-tone (grayscale) images, and not silhouette or still images, Baird achieved this privately on October 2, 1925, and gave the world's first public demonstration of a working television system to members of the Royal Institution and a newspaper reporter 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 disc embedded with a double spiral of lenses, had only 30 lines, just enough to reproduce a recognizable human face. In 1928 Baird's company (Baird Television Development Company / Cinema Television) broadcast the first transatlantic television signal, between London and New York, and the first shore to ship transmission. He also demonstrated an electromechanical colour, infrared (dubbed "Noctovision"), and stereoscopic television, using additional lenses, disks and filters. In parallel he developed a video disk recording system dubbed "Phonovision"; a number of the Phonovision[http://www.tvdawn.com/tvimage.htm] recordings, dating back to 1927, still exist. In 1929 he became involved in the first experimental electromechanical television service in Germany. In 1931 he made the first live transmission, of the Epsom Derby. In 1932 he demonstrated ultra-short wave television. Baird's electromechanical system reached a peak of 240 lines of resolution on BBC television broadcasts in 1936, before being discontinued in favor of a 405 line all-electronic system. In the U.S., Charles Francis Jenkins was able to demonstrate on June 13, 1925, the transmission of the silhouette image of a toy windmill in motion from a naval radio station to his laboratory in Washington, using a lensed disc scanner with 48 lines per picture, 16 pictures per second. AT&T's Bell Telephone Laboratories transmitted half-tone images of transparencies in May 1925. But Bell Labs gave the most dramatic demonstration of television yet on April 7, 1927, when it field tested reflected-light television systems using small-scale (2 by 2.5 inches) and large-scale (24 by 30 inches) viewing screens over a wire link from Washington to New York City, and over-the-air broadcast from Whippany, New Jersey. The subjects, which included Secretary of Commerce Herbert Hoover, were illuminated by a flying spot beam and scanned by a 50-aperture disc at 16 pictures per second.

Electronic television

Herbert Hoover Although the discoveries of Nipkow, Rosing, Baird and others were extraordinary, little of their technology is used in modern television. By 1934, all electromechanical television systems were outmoded, although electromechanical broadcasts continued on some stations until 1939. A.A. Campbell-Swinton wrote a letter to Nature on the 18 June 1908 describing his concept of electronic television using the cathode ray tube, which had been invented in 1897 by the German physicist and Nobel prize winner Karl Ferdinand Braun. He proposed using an electron beam in both the camera and the receiver, which could be steered electronically to produce moving pictures. He lectured on the subject in 1911 and displayed circuit diagrams, but no one, including Swinton, knew how to realize the design. Although his system was never built, the cathode ray tube did come to be used to display images in almost all television sets and computer monitors until the invention of the LCD panel. A fully electronic system was first achieved by Philo Taylor Farnsworth on September 7, 1927, although the low-resolution, light-insensitive camera tube limited the image to a plate of glass painted black, with a straight line etched across it, rotated in front of a bright carbon arc lamp. Seven years later, on August 25, 1934, at the Franklin Institute in Philadelphia, Farnsworth gave the world's first public demonstration of a working, all-electronic television system, with 220 lines per picture, 30 pictures per second. Over a three week period, vaudeville acts, athletic and sports demonstrations, politicians, and hundreds of ordinary citizens were captured on Farnsworth's cameras in the open air and simultaneously shown on his receiving sets. Farnsworth, a Mormon farm boy from Rigby, Idaho, first envisioned his system at age 14. He discussed the idea with his high school chemistry teacher, who could think of no reason why it would not work (Farnsworth would later credit this teacher, Justin Tolman, as providing key insights into his invention). He continued to pursue the idea at Brigham Young Academy (now Brigham Young University). At age 21, he demonstrated a working system at his own laboratory in San Francisco. His breakthrough freed television from reliance on spinning discs and other mechanical parts. All modern picture tube televisions descend directly from his design. Vladimir Kosma Zworykin is also sometimes cited as the father of electronic television because of his invention of the iconoscope in 1923 and his invention of the kinescope in 1929. His design was one of the first to demonstrate a television system with all the features of modern picture tubes. His previous work with Rosing on electromechanical television gave him key insights into how to produce such a system, but his (and RCA's) claim to being its original inventor was largely invalidated by three facts: a) Zworykin's 1923 patent presented an incomplete design, incapable of working in its given form (it was not until 1933 that Zworykin achieved a working implementation), b) the 1923 patent application was not granted until 1938, and not until it had been seriously revised, and c) courts eventually found that RCA was in violation of the television design patented by Philo Taylor Farnsworth, whose lab Zworykin had visited while working on his designs for RCA. The controversy over whether it was first Farnsworth or Zworykin who invented modern television is still hotly debated today. Some of this debate stems from the fact that while Farnsworth appears to have gotten there first as an inventor, RCA brought television sets to market before Farnsworth, and it was RCA employees who first wrote the history of television. Even though Farnsworth eventually won the legal battle over this issue, he was never able to fully capitalize financially on his invention.

Color television

Most television researchers appreciated the value of color image transmission, with an early patent application in Russia in 1889 for a mechanically-scanned color system showing how early the importance of color was realized. John Logie Baird demonstrated the world's first color transmission on July 3, 1928, using scanning discs at the transmitting and receiving ends with three spirals of apertures, each spiral with filters of a different primary color; and three light sources at the receiving end, with a commutator to alternate their illumination. Color television in the United States had a protracted history due to conflicting technical systems vying for approval by the Federal Communications Commission for commercial use. Mechanically scanned color television was demonstrated by Bell Laboratories in June 1929 using three complete systems of photoelectric cells, amplifiers, glow-tubes, and color filters, with a series of mirrors to superimpose the red, green, and blue images into one full color image. In the electronically scanned era, the first color television demonstration was on February 5, 1940, when RCA privately showed to members of the FCC at the RCA plant in Camden, New Jersey, a television receiver producing images in color by a field sequential color system. CBS began non-broadcast color experiments using film as early as August 28, 1940, and live cameras by November 12. The CBS "field sequential" color system was partly mechanical, with a disc made of red, blue, and green filters spinning inside the television camera at 1,200 rpm, and a similar disc spinning in synchronization in front of the cathode ray tube inside the receiver set. RCA's later "dot sequential" color system had no moving parts, using a series of dichroic mirrors to separate and direct red, green, and blue light from the subject through three separate lenses into three scanning tubes, and electronic switching that allowed the tubes to send their signals in rotation, dot by dot. These signals were sorted by a second switching device in the receiver set and sent to red, green, and blue picture tubes, and combined by a second set of dichroic mirrors into a full color image. The first field test (i.e., broadcast) of color television was by NBC (owned by RCA) on February 20, 1941. CBS began daily color field tests on June 1, 1941. These color systems were not compatible with existing black and white television sets, and as no color television sets were available to the public at this time, viewership of the color field tests was limited to RCA and CBS engineers and the invited press. The War Production Board halted the manufacture of television and radio equipment for civilian use from April 1, 1942 to October 1, 1945, limiting any opportunity to introduce color television to the general public. The post-war development of color television was dominated by three systems competing for approval by the FCC as the U.S. color broadcasting standard: CBS's field sequential system, which was incompatible with existing black and white sets without an adaptor; RCA's dot sequential system, which in 1949 became compatible with existing black and white sets; and CTI's system (also incompatible with existing black and white sets), which used three camera lenses, behind which were color filters that produced red, green, and blue images side by side on a single scanning tube, and a receiver set that used lenses in front of the picture tube (which had sectors treated with different phosphorescent compounds to glow in red, green, or blue) to project these three side by side images into one combined picture on the viewing screen. After a series of hearings beginning in September 1949, the FCC found the RCA and CTI systems fraught with technical problems, inaccurate color reproduction, and expensive equipment, and so formally approved the CBS system as the U.S. color broadcasting standard on October 11 1950. An unsuccessful lawsuit by RCA delayed the world's first network color broadcast until June 25 1951, when a musical variety special titled simply Premiere was shown over a network of five east coast CBS affiliates. Viewership was again extremely limited: the program could not be seen on black and white sets, and Variety estimated that only thirty prototype color receivers were available in the New York area. Regular color broadcasts began that same week with the daytime series The World Is Yours and Modern Homemakers. While the CBS color broadcasting schedule gradually expanded to twelve hours per week (but never into prime time), and the color network expanded to eleven affiliates as far west as Chicago, its commercial success was doomed by the lack of color receivers necessary to watch the programs, the refusal of television manufacturers to create adaptor mechanisms for their existing black and white sets, and the unwillingness of advertisers to sponsor broadcasts seen by almost no one. In desperation, CBS bought a television manufacturer, and on September 20, 1951, production began on the first and only CBS color television model. But it was too little, too late. Only 200 sets had been shipped, and only 100 sold, when CBS pulled the plug on its color television system on October 20, 1951, and bought back all the CBS color sets it could to prevent law suits by disappointed customers. Starting before CBS color even got on the air, the U.S. television industry, represented by the National Television System Committee, worked in 1950-1953 to develop a color system that was compatible with existing black and white sets and would pass FCC quality standards, with RCA developing the hardware elements. When CBS testified before Congress in March 1953 that it had no further plans for its own color system, the path was open for the NTSC to submit its petition for FCC approval in July 1953, which was granted in December. The first publicly announced experimental TV broadcast of a program using the NTSC-RCA "compatible color" system was an episode of NBC's Kukla, Fran and Ollie on August 30, 1953. NBC made the first coast-to-coast color broadcast when it covered the Tournament of Roses Parade on January 1 1954, with public demonstrations given across the United States on prototype color receivers. A few days later Admiral brought out the first commercially made color television set using the RCA standards, followed in March by RCA's own model. Television's first prime time network color series was The Marriage, a situation comedy broadcast live by NBC in the summer of 1954. NBC's anthology series Ford Theatre became the first color filmed series that October. NBC was naturally at the forefront of color programming because its parent company RCA manufactured the most successful line of color sets in the 1950s. CBS and ABC, which were not affiliated with set manufacturers, and were not eager to promote their competitor's product, dragged their feet into color, with ABC delaying its first color series (The Flintstones and The Jetsons) until 1962. The Du Mont network, although it did have a television-manufacturing parent company, was in financial decline by 1954 and was dissolved two years later. Thus the relatively small amount of network color programming, combined with the high cost of color television sets, meant that as late as 1964 only 3.1 percent of television households in the U.S. had a color set. NBC provided the catalyst for rapid color expansion by announcing that its prime time schedule for fall 1965 would be almost entirely in color (the exception being I Dream of Jeannie). All three broadcast networks were airing full color prime time schedules by the 1966–67 broadcast season. But the number of color television sets sold in the U.S. did not exceed black and white sales until 1972, which was also the first year that more than fifty percent of television households in the U.S. had a color set. In Mexico, Guillermo González Camarena (1917–1965), invented the early color television transmission system. He received patents for color television systems in 1940 (U.S. Patent 1942 (2296019), 1960 and 1962. The 1942 patent was for a mechanically scanned color filter adapter for an existing monochrome electronic transmission system. In August 31, 1946 he sent his first color transmission from his lab in the offices of The Mexican League of Radio Experiments in Lucerna St. #1, in Mexico City. The video signal was transmitted at a frequency of 115 MHz. and the audio in the 40 metre band. European color television was developed somewhat later and was hindered by a continuing division on technical standards. Having decided to adopt a higher-definition 625-line system for monochrome transmissions, with a lower frame rate but with a higher overall bandwidth, Europeans could not directly adopt the U.S. color standard, which was widely perceived as wanting anyway, because of its tint control problems. There was also less urgency, since there were fewer commercial motivations, European television broadcasters being predominantly state-owned at the time. As a consequence, although work on various color encoding systems started already in the 1950s, with the first SECAM patent being registered in 1956, many years had passed till the first broadcasts actually started in 1967. Unsatisfied with the performance of NTSC and of initial SECAM implementations, the Germans unveiled PAL (phase alternating line) in 1963, staying closer to NTSC but borrowing some ideas from SECAM. The French continued with SECAM, notably involving Russians in the development. The first regular colour broadcasts in Europe were by BBC2 beginning on July 1, 1967, using PAL. Germans did their first broadcast in September (PAL), while the French in October (SECAM). PAL was eventually adopted by West Germany, the UK, Australia, New Zealand, much of Africa, Asia and South America, and most Western European countries except France. In addition to France and Luxembourg, SECAM was adopted by Soviet Union, much of Eastern Europe, much of Africa and of the Middle East. Both systems broadcast on UHF frequencies, the VHF being used for legacy black and white, 405 lines in UK or 819 lines in France, till the beginning of the eighties. It should be noted that some British television programmes, particularly those made by or for ITC Entertainment, were made in colour before the introduction of colour television to the UK, for the purpose of sales to US networks. The first British show to be made in colour was the drama series The Adventures of Sir Lancelot (1956-57), which was initially made in black and white but later shot in colour for sale to the NBC network in the United States. In Japan, NHK introduced color television in the year 1960.

Broadcast television

NHK The first regularly scheduled television service in the United States began on July 2, 1928. The Federal Radio Commission authorized C.F. Jenkins to broadcast from experimental station W3XK in a suburb of Washington, D.C. But for at least the first eighteen months, only silhouette images from motion picture film were broadcast due to the narrow 10kHz bandwidth allotted by the FRC. General Electric's experimental station in Schenectady, New York, on the air sporadically since January 13, 1928, was able to broadcast reflected-light, 48-line images via shortwave as far as Los Angeles, and by September was making four television broadcasts weekly. CBS's New York City station W2XAB began broadcasting the first regular seven days a week television schedule in the United States on July 21, 1931, with a 60-line electromechanical system. The first broadcast included Mayor Jimmy Walker, the Boswell Sisters, Kate Smith, and George Gershwin. The service ended in February 1933. By 1935, electromechanical television broadcasting had ceased in the United States except for a handful of stations run by public universities that continued to 1939. The Federal Communications Commission saw television in the continual flux of development with no consistent technical standards, hence all such stations in the U.S. were granted only experimental and not commercial licenses, hampering television's economic development. Just as importantly, Philo Farnsworth's 1934 demonstration of an all-electronic system pointed the direction of television's future. On June 15, 1936, Don Lee Broadcasting began a month-long demonstration of all-electronic television in Los Angeles on W6XAO (later KTSL) with a 300-line image from motion picture film. RCA demonstrated in New York City a 343-line electronic television broadcast, with live and film segments, to its licensees on July 7, 1936, and made its first public demonstration to the press on November 6. By April 1939, regularly scheduled 441-line electronic television broadcasts were available in New York City and Los Angeles, and by November on General Electric's station in Schenectady. With the adoption of NTSC television engineering standards in 1941, the FCC saw television ready for commercial licensing, with the first such licenses issued to NBC and CBS owned stations in New York on July 1, 1941, followed by Philco's station in Philadelphia. Electromechanical broadcasts began in Germany in 1929, but were without sound until 1934. Network electronic service started on March 22, 1935, on 180 lines using only telecine transmission of film or an intermediate film system. Live transmissions began on January 15, 1936. The Berlin Summer Olympic Games were televised, using both direct television and intermediate film cameras, to 28 public television rooms in Berlin and Hamburg in August 1936. The Germans had a 441-line system on the air in February 1937, and during World War II brought it to France, where they broadcast off the Eiffel Tower. The first British television broadcast was made by Baird Television's electromechanical system over the BBC radio transmitter in September 1929. Baird provided a limited amount of programming five days a week by 1930. On August 22, 1932, BBC launched its own regular service using Baird's 30-line electromechanical system, continuing until September 11, 1935. On November 2, 1936 the BBC began broadcasting a dual-system service, alternating on a weekly basis between Marconi-EMI's 405-line standard and Baird's improved 240-line standard, from Alexandra Palace in London, making the BBC the world's first regular high-definition television service. The corporation decided that Marconi-EMI's electronic picture gave the superior picture, and the Baird system was dropped in February 1937. The outbreak of the Second World War caused the BBC service to be suspended on September 1, 1939, resuming from Alexandra Palace on June 7, 1946. The Soviet Union began offering 30-line electromechanical test broadcasts in Moscow on October 31, 1931, and a commercially manufactured television set in 1932. The first experimental transmissions of electronic television took place in Moscow on March 9, 1937, using equipment manufactured and installed by RCA. Regular broadcasting began on December 31, 1938. The first regular television transmissions in Canada began in 1952 when the CBC put two stations on the air, one in Montreal, Quebec on September 6, and another in Toronto, Ontario two days later. two days later The first live transcontinental television broadcast took place in San Francisco, California from the Japanese Peace Treaty Conference on September 4, 1951. In 1958, the CBC completed the longest television network in the world, from Sydney, Nova Scotia to Victoria, British Columbia. Reportedly, the first continuous live broadcast of a breaking news story in the world was conducted by the CBC during the Springhill Mining Disaster which began on October 23 of that year. Programming is broadcast on television stations (sometimes called channels). At first, terrestrial broadcasting was the only way television could be distributed. Because bandwidth was limited, government regulation was normal. In the U.S., the Federal Communications Commission allowed stations to broadcast advertisements, but insisted on public service programming commitments as a requirement for a license. By contrast, the United Kingdom chose a different route, imposing a television licence fee on owners of television reception equipment, to fund the BBC, which had public service as part of its Royal Charter. Development of cable and satellite means of distribution in the 1970s pushed businessmen to target channels towards a certain audience, and enabled the rise of subscription-based television channels, such as HBO and Sky. Practically every country in the world now has developed at least one television channel. Television has grown up all over the world, enabling every country to share aspects of their culture and society with others. By the late 1980s, 98% of all homes in the U.S. had at least one TV set. On average, Americans watch four hours of television per day. An estimated two-thirds of Americans got most of their news about the world from TV, and nearly half got all of their news from TV. These figures are now estimated to be significantly higher.

Technology

Broadcasting

There are many means of distributing television broadcasts, including both analogue and digital versions of:
- Terrestrial television
- Stratovision (From aircraft flying in a loop)
- Satellite television
- Cable television
- MMDS (Wireless cable)

Receiving

Television sets

In television's electromechanical era, commercially made television sets were sold from 1928 to 1934 in the United Kingdom, United States, and Russia. The earliest commercially made sets sold by Baird in the U.K. and the U.S. in 1928 were radios with the addition of a television device consisting of a neon tube behind a mechanically spinning disk (the Nipkow disk) with a spiral of apertures that produced a red postage-stamp size image, enlarged to twice that size by a magnifying glass. The "televisor" was also available without the radio. The Baird televisor sold in 1930-1933 is considered the first mass-produced set, selling about a thousand units. The first commercially made electronic television sets with cathode ray tubes were manufactured by Telefunken in Germany in 1934, followed by other makers in Britain (1936) and America (1938). The cheapest of the pre-War World II factory-made American sets, a 1938 image-only model with a 3-inch (8 cm) screen, cost US$125, the equivalent of US$1,732 in 2005. The cheapest model with a 12-inch (30 cm) screen was $445 ($6,256). An estimated 19,000 electronic television sets were manufactured in Britain, and about 1,600 in Germany, before World War II. About 7,000-8,000 electronic sets were made in the U.S. before the War Production Board halted manufacture in April 1942, which resumed in October 1945. Television usage in the United States skyrocketed after World War II with the lifting of the manufacturing freeze, war-related technological advances, the gradual expansion of the television networks westward, the drop in set prices caused by mass production, increased leisure time, and additional disposable income. While only 0.5% of U.S. households had a television set in 1946, 55.7% had one in 1954, and 90% by 1962. In Britain, there were 15,000 television households in 1947, 1.4 million in 1952, and 15.1 million by 1968. For many years different countries used different technical standards. France initially adopted the German 441-line standard but later upgraded to 819 lines, which gave the highest picture definition of any analogue TV system, approximately four times the resolution of the British 405-line system. Eventually the whole of Europe switched to the 625-line PAL standard, once more following Germany's example. Meanwhile in North America the original NTSC 525-line standard from 1941 was retained. NTSC Television in its original form involves sending images and sound over radio waves in the VHF and UHF bands, which are received by a television set. Over-the-air broadcast television requires an antenna (aerial). This can be an outdoor Yagi antenna. In strong signal areas the antenna can be indoors, attached to or near the receiver, such as an adjustable dipole antenna called "rabbit ears" for the VHF band and a small loop antenna for the UHF band.

Specifications

Modern displays

Starting in the 1990s, modern television sets diverged into three different trends:
- standalone TV sets;
- integrated systems with DVD players and/or VHS VCR capabilities built into the TV set itself (mostly for small size TVs with up to 21" screen, the main idea is to have a complete portable system);
- component systems with separate big-screen video monitor, tuner, audio system which the owner connects the pieces together as a high-end home theater system. This approach appeals to videophiles who prefer components that can be upgraded separately. There are many kinds of video monitors used in modern TV sets. The most common are direct view CRTs for up to 40in (100cm) (in 4:3) and 46in (115cm) (in 16:9) diagonally; most big screen TVs (up to over 100 inch (254 cm)) use projection technology. Three types of projection systems are used in projection TVs: CRT-based, LCD-based, and DLP(reflective micromirror chip)-based. Modern advances have brought flat panels to TV that use active matrix LCD or plasma display technology. Flat panel LCDs and plasma displays are as little as 4in (10cm) thick and can be hung on a wall like a picture or put over a pedestal. They are multifunctional, because they are used like computer monitors too (VGA and DVI or HDMI connections). Some TVs integrate a pair of ports to connect computer cases and peripherals to it or to connect the set to an A/V home network (HAVI) (USB port for cord connection and BlueTooth/WiFi for wireless). Today, some LCD and Plasma sets have SD Card slots, so users can view pictures from a digital camera. On the new Panasonic LCDs and Plasmas (Viera), users have the capability to record onto SD card and then play it back on a hand-held PC or digital camera (anything that allows MPEG4). With SD cards now available with 1G of memory (soon 2GB, and Panasonic is also working on one that contains over 30GB of memory), a user can record over 1,000 minutes at low quality, and around 80 minutes on the highest quality. The playback of the recording is not brilliant, but these are the first generation. They will get better with time.

Signal connections

The number of ways to connect a video device to a television has increased over the years: WiFi
- HDMI - a compact 19 to 29 pin connector that carries digital video and digital audio signals. Essentially an enhanced version of DVI that includes digital audio. This is the most advanced form of connection currently available. DVI
- DVI - a 17 to 29 pin connector that carries digital video signals, designed to carry HDTV but also used in current DVD players and latest digital displays. Copy protection is available using HDCP. HDCP
- Component video - three separate RCA jacks (colored red, green and blue) carry three video signals, one brightness (luminance) and two colors (chromas), and is usually referred to as "Y, B-Y, R-Y", "Y Cr Cb" (interlaced) or "Y Pr Pb" (progressive), or YUV. Audio is not carried on this cable. This connection provides for picture quality superior to S-Video and is typically used in home theater for DVDs, satellite and analogue HDTV; less common in Europe but is starting to become more widely available. Europe
- SCART - a large 21 pin connector that may carry: one video signal composite video; or two video signals S-Video; or for picture quality similar to component video, three signals of separate red, green and blue or RGB; or for best picture quality, four video signals of separate red, green, blue and sync or RGBS; plus right and left line-level audio channels; along with a number of control signals including an aspect-ratio flag (e.g. widescreen). This system has been standard in Europe since mid-1980s for all consumer electronics, which meant that RGBS was available on even the earliest PAL DVD players and satellite receivers. Japan uses a 21 pin RGB connector which is visually similar to SCART but with different pin configurations. Japan
- S-Video - small round connector with two separate video signals, one carrying brightness (luminance), the other carrying color (chroma). Also referred to as Y/C video. Provides most of the benefit of component video, with slightly less color fidelity. Use started in the 1980s for S-VHS, Hi-8, and early NTSC DVD players to relay high quality video before component was available. Audio is not carried on this cable. Hi-8
- Composite video - The most common form of connecting external devices, putting all the video information into one signal. Most televisions provide this option with a yellow RCA jack. Audio is not carried on this cable, though two separate cables with similar red and white RCA jacks for right and left line-level audio are commonly bonded to composite video cables.
- Coaxial RF - All audio channels and picture components are transmitted through one coaxial cable and modulated on a radio frequency. Most TVs manufactured during the past 15–20 years accept coaxial connection, and the video is typically "tuned" on channel 3 or 4. This is the type of cable usually used for cable television. Most modern DVD players and other video devices no longer modulate RF output, so very old TV sets made before composite video jacks became commonplace will need a modulator.

Aspect ratios

Mechanically scanned television as first demonstrated by John Logie Baird in 1926 used a 7:3 vertical aspect ratio, oriented for the head and shoulders of a single person in close-up. Most of the early electronic TV systems from the mid-1930s onward shared the same aspect ratio of 4:3 which was chosen to match the Academy Ratio used in cinema films at the time. This ratio was also square enough to be conveniently viewed on round cathode-ray tubes (CRTs), which were all that could be produced given the manufacturing technology of the time. (Today's CRT technology allows the manufacture of much wider tubes, and the flat screen technologies which are becoming steadily more popular have no aspect ratio limitations at all.) The BBC's television service used a more squarish [http://tcc.members.beeb.net/tchistory.html 5:4] ratio from 1936 to circa 1949, when it too switched to a 4:3 ratio. In the 1950s, movie studios moved towards widescreen aspect ratios such as Cinerama in an effort to distance their product from television. Although this was initially just a gimmick widescreen is still the format of choice today and square aspect ratio movies are rare. Some people argued that widescreen is actually a disadvantage when showing objects that are tall instead of panoramic, others would say that natural vision is more panoramic than tall, and therefore widescreen is easier on the eye. The switch to digital television systems has been used as an opportunity to change the standard television picture format from the old ratio of 4:3 (approximately 1.33:1) to an aspect ratio of 16:9 (approximately 1.78:1). This enables TV to get closer to the aspect ratio of modern widescreen movies, which range from 1.78:1 through 1.85:1 to 2.35:1. There are two methods for transporting widescreen content, the better of which uses what is called anamorphic widescreen format. This format is very similar to the technique used to fit a widescreen movie frame inside a 1.33:1 35mm film frame. The image is squashed horizontally when recorded, then expanded again when played back. The anamorphic widescreen 16:9 format was first introduced via European PAL-Plus television broadcasts and then later on "widescreen" DVDs; the ATSC HDTV system uses straight widescreen format, no image squashing or expanding is used. Recently "widescreen" has spread from television to computing where both desktop and laptop computers are commonly equipped with widescreen displays, and it remains to be seen whether Work or movie enjoyment will take over. There are some complaints about distortions of movie picture ratio due to some DVD playback software not taking account of aspect ratios; but this will subside as the DVD playback software matures. Furthermore, computer and laptop widescreen displays are in the 16:10 aspect ratio both physically in size and in pixel counts, and not in 16:9 of consumer televisions, leading to further complexity. This was a result of widescreen computer display engineers' uninformed assumption that people viewing 16:9 content on their computer would prefer that an area of the screen be reserved for playback controls or subtitles, as opposed to viewing content full-screen.

Aspect ratio incompatibility

The television industry changing aspect ratios is not without teething difficulties, and can present a considerable problem. Displaying a widescreen aspect (rectangular) image on a conventional aspect (square) display can be shown:
- in "letterbox" format, with black horizontal bars at the top and bottom
- with part of the image being cropped, usually the extreme left and right of the image being cut off (or in "pan and scan", parts selected by an operator)
- with the image horizontally compressed A conventional aspect (square) image on a widescreen aspect (rectangular) display can be shown:
- in "pillarbox" format, with black vertical bars to the left and right
- with upper and lower portions of the image cut off
- with the image horizontally distorted A common compromise is to shoot or create material at an aspect ratio of 14:9, and to lose some image at each side for 4:3 presentation, and some image at top and bottom for 16:9 presentation. Horizontal expansion has advantages in situations in which several people are watching the same set, as it compensates for watching at an oblique angle.

Sound

Television add-ons

Today there are many add-ons for the television set. A few add-ons include Video Game Consoles, VCRs, Cable Boxes, Satellite Boxes, DVD players, or Digital Video Recorders, the television add-on market is ever growing.

New developments

- Broadcast flag
- CableCARD™
- Digital Light Processing (DLP)
- Digital Rights Management (DRM)
- Digital television (DTV)
- Digital Video Recorders
- Direct Broadcast Satellite TV (DBS)
- DVD
- Flicker-free (100Hz)
- High Definition TV (HDTV)
- High-Definition Multimedia Interface (HDMI)
- IPTV
- Internet television
- LCD and Plasma display Flat Screen TV
- Pay Per View
- Picture-in-picture (PiP)
- Video on-demand (VOD)
- Ultra High Definition Video (UHDV)
- Web TV

Geographical usage

Content

Advertising

Since their inception in the USA in 1941, TV commercials have become one of the most effective, most pervasive, and most popular methods of selling products of many sorts, especially consumer goods. U.S. advertising rates are determined primarily by Nielsen ratings. The exception to this is the publicly-funded British Broadcasting Corporation.

Programming

Getting TV programming shown to the public can happen in many different ways. After production the next step is to market and deliver the product to whatever markets are open to using it. This typically happens on two levels: #Original Run or First Run - a producer creates a program of one or multiple episodes and shows it on a station or network which has either paid for the production itself or to which a license has been granted by the producers to do the same. #Syndication - this is the terminology rather broadly used to describe secondary programming usages (beyond original run). It includes secondary runs in the country of first issue, but also international usage which may or may not be managed by the originating producer. In many cases other companies, TV stations or individuals are engaged to do the syndication work, in other words to sell the product into the markets they are allowed to sell into by contract from the copyright holders, in most cases the producers. In most countries, the first wave occurs primarily on FTA television, while the second wave happens on subscription TV and in other countries. In the U.S. however, the first wave occurs on the FTA networks and subscription services, and the second wave travels via all means of distribution. First run programming is increasing on subscription services outside the U.S., but few domestically produced programs are syndicated on domestic FTA elsewhere. This practice is increasing however, generally on digital only FTA channels, or with subscriber-only first run material appearing on FTA. Unlike the U.S., repeat FTA screenings of a FTA network program almost only occur only on that network. Also, affiliates rarely buy or produce non-network programming that isn't intensely local.

Social aspects

Alleged dangers

Paralleling television's growing primacy in family life and society, an increasingly vocal chorus of legislators, scientists and parents are raising objections to the uncritical acceptance of the medium. For example, the Swedish government imposed a total ban on advertising to children under twelve in 1991 (see advertising). In the U.S., the [http://www.mediafamily.org/facts/facts_tveffect.shtml National Institute on Media and the Family] (not a government agency) points out that U.S. children watch an average of 25 hours of television per week and features studies showing it interferes with the educational and maturational process. A February 23 2002 article in [http://www.sciam.com/print_version.cfm?articleID=0005339B-A694-1CC5-B4A8809EC588EEDF Scientific American] suggested that compulsive television watching was no different from any other addiction, a finding backed up by reports of withdrawal symptoms among families forced by

Movie projector

:This article is concerned with technical aspects of moving film projection. For historical aspects see the article history of cinema history of cinema movie projector with a Zenith X4000H lamphouse]] A movie projector is an opto-mechanical device for displaying moving pictures by projecting them on a projection screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras.

Physiology

According to the theory of persistence of vision, the perceptual processes of the brain and the retina of the human eye retains an image for a brief moment of time. This theory is said to account for the illusion of motion which results when a series of film images are displayed in quick succession, rather than the perception of the individual frames in the series. Persistence of vision should be compared with the related phenomena of beta movement and phi movement. A critical part of understanding these visual perception phenomena is that the eye is not a camera, ie: there is no "frame rate" or "scan rate" in the eye. Instead, the eye/brain system has a combination of motion detectors, detail detectors and pattern detectors, the outputs of all of which are combined to create the visual experience. The frequency at which flicker becomes invisible is called the flicker fusion threshold, and is dependent on the level of illumination. Generally, the frame rate of 16 frames per second (fps) is regarded as the lowest frequency at which continuous motion is perceived by humans. (Interestingly this threshold varies across different species; a higher proportion of rod cells in the retina will create a higher threshold level.) It is possible to view the black space between frames and the passing of the shutter by the following technique:
Close your eyelids, then periodically rapidly blink open and closed. If done fast enough you will be able to randomly "trap" the image between frames, or during shutter motion. This will not work with television due to the persistence of the phosphors nor with LCD or DLP light projectors due to the continuity of image, although certain color artifacts may appear with some digital projection technologies. Since the birth of sound film, virtually all film projectors in commercial movie theaters project at a constant speed of 24 fps. This speed was chosen for financial and technical reasons - it was the slowest speed (and thus required the least film stock and was cheapest for producers) at which a satisfactory reproduction and amplification of sound could be conducted. There are some specialist formats (eg Showscan and Maxivision) which project at higher rates, often 48 fps. Silent films usually were not projected at constant speeds [http://www.cinemaweb.com/silentfilm/bookshelf/18_car_1.htm] but rather were varied throughout the show at the discretion of the projectionist, often with some notes provided by the distributor. Speeds ranged from about 18 fps on up - sometimes even faster than modern sound film speed (24 fps). Contrary to received opinion, 16 fps - though sometimes used as a camera shooting speed - was dangerously inadvisable for projection, due to the high risk of the nitrate-base prints catching fire in the projector. (A dramatic rendition of a nitrate print fire and its potentially devastating effects is famously found in Cinema Paradiso, which revolves around the goings-on of a projectionist.)

Principles of operation

Projection elements

As in a slide projector there are essential optical elements:

Light source

An incandescent lamp or an electric arc light produces illuminating photons. The traditional carbon arc or modern xenon arc light source produces sufficient heat to burn the film should the film remain stationary for more than a fraction of a second. Xenons were introduced in the 1950s and are now the more common source, being easier and safer to maintain for the most part.

Reflector and condenser lens

A curved reflector redirects light that would otherwise be wasted toward the condensing lens. A positive curvature lens concentrates the reflected and direct light toward the film gate.

Douser

(Also spelled dowser.) A metal blade which cuts off light before it can get to the film - usually this is part of the lamphouse. Some projectors have both a manually controlled and electronically one each; the electronic one is used for changeovers. Dousers protect the film when the lamp is on but the film is not moving, preventing the film from melting from prolonged exposure to the direct heat of the lamp.

Film gate and single image

A single image of the series of images comprising the movie is positioned and held flat within an aperture called the gate. The gate also provides a slight amount of friction so that the film does not advance or retreat except when driven to advance the film to the next image.

Shutter

A rotating petal or gated cylindrical shutter interrupts the emitted light during the time the film is advanced to the next frame. Modern shutters are designed with a flicker-rate of two or even sometimes three times the frame rate of the film, so as to reduce the perception of screen flickering. (See Frame rate and Flicker fusion threshold.)

Imaging lens and aperture plate

A lens system with multiple optical elements directs the image of the film to a viewing screen. Different lenses are used for different aspect ratios. Each of these lenses comes with an aperture plate, a piece of metal with a precisely cut rectangular hole in the middle of equivalent aspect ratio. The aperture plate is placed just behind the gate, and masks off any light from hitting the image outside of the area intended to be shown (most modern films have extra image on the frame that is meant to be masked off in the projector).

Viewing screen

In most cases this is a reflective surface which may be either aluminized (for high contrast in moderate ambient light) or a white surface with small glass beads (for high brilliance under dark conditions). In a commercial theater, the screen also has hundreds of small, evenly spaced holes in order to allow the passage of air to and from the speakers and subwoofer which often are directly behind it.

Film transport elements

Film supply and takeup

Two reel system

The two reel system is also known as a changeover system, after the switching mechanism that operates between the end of one reel and the beginning of the next. In a two reel system the feed reel has a slight drag to maintain tensioning in the film, while the takeup reel is driven with a constant tension by a mechanism that is allowed to slip. The two reel system was almost universally used before the advent of the single reel system for movie theaters in order to be able to show feature-length films. Although one reel long-play systems tend to be more popular with the newer multiplexes, the two reel system is still in significant use to this day. The projector operator operates two projectors, threading one with the next reel while the other projector plays the current reel. As the current reel approaches its end, the projectionist looks for cues, also known as cigarette burns, at the upper right corner of the picture. Usually these are dots or circles, although they can also be slashes. (Some older films have occasionally been known to have used squares or triangles, and even positioned the cues in the middle of the right edge of the picture.) The first cue appears twelve feet (3.7 m) or eight seconds at 24 frame/s before the end of the reel, and signals the projectionist to start the motor of the projector containing the next reel. After another ten and a half feet (3.2 m) or seven seconds at 24 frame/s, the changeover cue should appear, which signals the projectionist to actually make the changeover. When this second cue appears, the projectionist has one and a half feet (457 mm) or one second at 24 frame/s to make the changeover - if it doesn't occur within one second, the tail black leader of the exhausted reel will be projected on the screen. On some projectors, the operator would be alerted to the change by a bell that operated when the feed reel rotation exceeded a certain speed (that reel rotates faster as the film is exhausted), or based on the diameter of the remaining film (Premier Changeover Indicator Pat.411992), although many such projectors do not have such an auditory system. During the actual operation of a changeover, the two projectors use an interconnected electrical control connected to the changeover button so that as soon as the button is pressed, the douser on the old reel is closed in sync with the douser for the new reel. If done properly, a changeover should be virtually unnoticeable to an audience. In older theaters, there may be manually operated, sliding covers in front of the projection booth's windows. A changeover with this system is often clearly visible as a wipe on the screen. The size of the reels can vary based on the projectors, but generally films are divided and distributed in reels of roughly 2000 feet (610 m) about 22 minutes at 24 frame/s. Some projectors can even accommodate up to 6000 feet (1,830 m), which minimizes the number of changeovers in a showing. Certain countries also divide their film reels up differently; Russian films, for example, often come on 1000 foot (305 m) reels, although it's likely that most projectionists working with changeovers would combine them into longer reels of at least 2000 feet (610 m), to minimize changeovers and also give sufficient time for threading and any possibly needed troubleshooting time.

Single reel system

There are two largely used single reel systems (also known as long-play systems) today: the tower system (vertical feed and takeup) and the platter system (horizontal feed and takeup). The tower system largely resembles the two reel system, except in that the tower itself is generally a separate piece of equipment used with a slightly modified standard projector. The feed and takeup reels are held vertically on the axis, except behind the projector, on oversized spools with 12,000 foot (3,660 m) capacity or about 133 minutes at 24 frame/s. This large capacity alleviates the need for a changeover on an average-length feature; all of the reels are spliced together into one giant one. The tower is designed with four spools, two on each side, each with its own motor. This allows the whole spool to be immediately rewound after a showing; the extra two spools on the other side allow for a film to be shown while another is being rewound or even made up directly onto the tower. Each spool requires its own motor in order to set proper tensioning for the film, since it has to travel (relatively) much further between the projector film transport and the spools. As each spool gains or loses film, the tension must be periodically checked and adjusted so that the film can be transported on and off the spools without either sagging or snapping. In a platter system the individual 20 minute reels of film are also spliced together as one large reel, but the film is then wound onto a horizontal rotating table called a platter. Three or more platters are stacked together to create a platter system. Most of the platters in a platter system will be occupied by film prints; whichever platter happens to be empty serves as the "take-up reel" to receive the film that is playing from another platter. The way the film is fed from the platter to the projector is not unlike an eight-track audio cartridge. Film is unwound from the center of the platter through a mechanism called a "brain" which controls the speed of the platter's rotation so that it matches the speed of the film as it is fed to the projector. The film winds through a series of rollers from the platter stack to the projector, through the projector, through another series of rollers back to the platter stack, and then onto the platter serving as the take-up reel. This system makes it possible to project a film several times a day without needing to rewind it. As the projectionist threads the projector for each showing, he transfers the brain mechanism from the empty platter to the full platter and the film then plays back onto the platter it came from. In the case of a double feature, each film plays from a full platter onto an empty platter, swapping positions on the platter stack throughout the day. The advantage of a platter is that the film isn't subjected to the stresses of being rewound each show. Rewinding risks rubbing the film against itself, which can cause scratching of the film and smearing of the emulsion which carries the pictures. The disadvantages of the platter system are that the film can acquire diagonal scratches on it if proper care is not taken while threading film from platter to projector, and the film has more opportunity to collect dust and dirt as long lengths of film are exposed to the air. A clean projection booth kept at the proper humidity is of great importance, as are cleaning devices that can remove dirt from the film print as it plays.

Automation and the rise of the multiplex

The single reel system can allow for the complete automation of the projection booth operations, given the proper auxiliary equipment. Since films are still transported in multiple reels they must be joined together when placed on the projector reel and taken apart when the film is to be returned to the distributor. It is the complete automation that has enabled the modern "multiplex" cinema - a single site typically containing from 16 to 24 theaters with only a few projection and sound technicians, rather than a platoon of projectionists. The multiplex also offers a great amount of flexibility to a theater operator, enabling multiple theaters to exhibit the same popular production in multiple theaters with staggered starting times. It is also possible, with the proper equipment installed, to "interlock", i.e. thread a single reel of film through multiple projectors. This is very useful when dealing with the mass crowds that an extremely popular film may generate in the first few days of showing, as it allows for a single reel to serve more patrons.

Feed and extraction sprockets

Smooth wheels with triangular pins called sprockets engage perforations punched into one or both edges of the film stock. These serve to set the pace of film movement through the projector and any associated sound playback system.

Film loop

As with motion picture cameras, the intermittent motion of the gate requires that there be loops above and below the gate in order to serve as a buffer between the constant speed enforced by the sprockets above and below the gate and the intermittent motion enforced at the gate. Some projectors also have a sensitive trip pin above the gate to guard against the upper loop becoming too big. If the loop hits the pin, it will close the dousers and stop the motor to prevent an excessively large loop from jamming the projector.

Film gate pressure plate

A spring loaded pressure plate functions to align the film in a consistent image plane, both flat and perpendicular to the optical axis. It also provides sufficient drag to prevent film motion during the frame display, while still allowing free motion under control of the intermittent mechanism. The plate also has spring-loaded runners to help hold film while in place and advance it during motion.

Intermittent mechanism

The intermittent mechanism can be constructed in different ways. For smaller gauge projectors (8mm and 16 mm), a pawl mechanism engages the film's sprocket hole one side, or holes on each side. This pawl advances only when the film is to be moved to the next image. As the pawl retreats for the next cycle it is drawn back and does not engage the film. This is similar to the claw mechanism in a motion picture camera. In 35 mm and 70 mm projectors, there usually is a special sprocket immediately underneath the pressure plate known as the intermittent sprocket. Unlike the all the other sprockets in the projector, which run continuously, the intermittent sprocket operates in tandem with the shutter, and only moves while the shutter is blocking the lamp, so that the motion of the film cannot be seen. It also moves in a discrete amount at a time, equal to the number of perforations that make up a frame (4 for 35 mm, 5 for 70 mm). The intermittent movement in these projectors is usually provided by a Maltese Cross mechanism. IMAX projectors use what is known as the rolling loop method, in which each frame is sucked into the gate by a vacuum, and positioned by registration pins in the perforations corresponding to that frame.

Types of projectors

Projectors are classified by the size of the film used, i.e. the film format. Typical film sizes:

8 mm

Long used for home movies before the video camera, this uses double sprocketed 16 mm film, which is run through the camera twice. The 16 mm film is then split lengthwise into two 8 mm pieces that are sliced to make a single projectable film with sprockets on one side.

Super 8

Developed by Kodak this film stock uses very small sprocket holes close to the edge that allow more of the film stock to be used for the images. This increases the quality of the image. The film is premade in the 8 mm width, not split during processing as is the earlier 8 mm. Magnetic stripes could be added to carry encoded sound to be added after film development.

16 mm

This was a popular format for audio-visual use in schools and as a high-end home entertainment system before the advent of broadcast television. It is also the smallest format that can carry an optically encoded sound track.

35 mm

The most common film size for theatrical productions during the first half of the 20th century. In fact, the common 35 mm camera, developed by Leica was designed to use this film stock and was originally intended to be used for test shots by movie directors and cinematographers.

70 mm

High end movie productions are often shot using this size and some theaters are capable of projecting it. 70 mm film is also used in both the flat and domed IMAX projection system. In IMAX the film is oriented for even more effective image area than in other formats. Some high quality productions intended for 35 mm anamorphic release are shot in and the master prints constructed using 70 mm film stock. A 35 mm print made from a 70 mm master print is significantly better in appearance than an all 35 mm process.

Sound

Regardless of the sound format, any sound represented on the film image itself will not be the sound for the particular frame it occupies. All optical sound formats must be offset from the image because the image is projected with intermittent motion. If the sound head on the projector was adjacent to the gate, the sound would be a jerky start-stop-start-stop and so on. Therefore the sound head requires continuous motion and will be located a certain number of frames before or after the gate. See the 35 mm film article for more information on both digital and analog methods.

Optical

With 16 mm and the larger sizes it is practical to add a narrow channel of optically encoded sound track. This is read using an illuminating light or laser and a photocell or photodiode. In 16 mm, this is a single mono track, and the sound head is 26 frames after the gate. In 35 mm, this can be mono or stereo, the latter including several different Dolby sound matrixing systems (including Dolby A and Dolby SR). The sound head is located twenty frames after the gate for 35 mm projectors. Originally optical sound was variable density, where the transparency/opacity level of the sound track was used to represent sound. This had disadvantages because the grain of the film caused a background hiss, and so was replaced with the now-universal standard variable area. In this system, a clear waveform on black background represents the sound, and the width of the waveform is equivalent to the amplitude. Variable area does have slightly less frequency response than variable density, it should be noted. In the 1970s and early 1980s, optical sound Super-8mm copies were produced mainly for airline in-flight movies. This technology was soon made obsolete by video equipment.

Digital

Modern theatrical systems use optical representations of digitally encoded multi-channel sound. An advantage of digital systems is that the offset between the sound and picture heads can be varied and then set with the digital processors. Digital sound heads are usually above the gate. All digital sound systems currently in use have the ability to instantly and gracefully fall back to the optical sound system should the digital data be corrupt or the whole system fail.

Cinema Digital Sound (CDS)

Created by Kodak and ORC (Optical Radiation Corporation), Cinema Digital Sound was the first attempt to bring multi-channel digital sound to first-run theaters. CDS was available on both 35 mm and 70 mm films. Film prints equipped with CDS did not have the conventional analog optical or magnetic soundtracks to serve as a "back-up" in case the digital sound was unreadable. Another disadvantage of not having an analog back-up track is that CDS required extra film prints be made for the theaters equipped to play CDS. The three formats that followed, Dolby Digital, DTS and SDDS, can co-exist with each other and the analog optical soundtrack on a single version of the film print. This means that a film print carrying all three of these formats (and the analog optical format, usually Dolby SR) can be played in whichever format the theater is equipped to handle. CDS did not achieve wide-spread use and ultimately failed. It premiered with the film Dick Tracy and was used with several other films, such as Days of Thunder and Terminator 2: Judgement Day.

Sony Dynamic Digital Stereo (SDDS)

SDDS sound runs on the outside of 35 mm film, between the perforations and the edges, on both edges of the film. It is the only digital system that can handle up to eight tracks of sound. The additional two tracks are for an extra pair of screen channels (Left Center and Right Center) located between the 3 regular screen channels (Left, Center and Right). A pair of CCD's located in a unit above the projector read the two SDDS tracks. The information is decoded and decompressed before being passed along to a Sony cinema sound processor, which means it can be equalized in the digital domain. In contrast, DTS and Dolby Digital soundtracks both are passed through to standard analog Dolby cinema sound processors which are also used for analog optical sound, so equalization of the sound is only analog. The digital compression of SDDS is better than DTS, but inferior to Dolby Digital. SDDS premiered with the film The Last Action Hero.

Dolby Digital

Also known to enthusiasts as Spectral Recording Digital or "SR-D." Sound is printed between the perforations and is 26 frames before the picture (the offset can be varied based on processing presets). It can handle up to six tracks, and has the best compression of the digital formats. The images between each perforation are read by a CCD located either above the projector or in the regular analog sound head below the film gate. The information is then decoded, decompressed, and converted to analog by an SR-D processor before going to a standard Dolby analog multi-format cinema sound processor. A consumer version of Dolby Digital is also used on most DVD's, often at higher data rates than the original film. Dolby Digital officially premiered with the film Batman Returns, but it was earlier tested at some screenings of Star Trek: The Undiscovered Country.

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