A drive-in theater or drive-in cinema is a form of cinema structure consisting of a large outdoor movie screen, a projection booth, a concession stand and a large parking area for automobiles. Within this enclosed area, customers can view movies from the comfort of their cars; some drive-ins have small playgrounds for a few picnic tables or benches. The screen can be as simple as a wall, painted white, or it can be a steel truss structure with a complex finish; the movie's sound was provided by speakers on the screen and by individual speakers hung from the window of each car, which were attached by wire. These systems were superseded by the more economical and easier to maintain method of broadcasting the soundtrack at a low output power on AM or FM radio to be picked up by a car radio; this allows the soundtrack to be picked up in stereo by the audience on an in-car stereo system, higher quality and fidelity than the simple speakers used in the old systems. A partial drive-in theater – Theatre de Guadalupe – was opened in Las Cruces, New Mexico, on April 23, 1915: Seven hundred people may be comfortably seated in the auditorium.
Automobile entrances and places for 40 or more cars within the theater grounds and in-line position to see the pictures and witness all performances on the stage is a feature of the place that will please car owners. The first movie shown by the Theatre de Guadalupe was Bags of Gold, produced by Siegmund Lubin. Theatre de Guadalupe soon was renamed De Lux Theater before closing in July 1916. In 1921, a drive-in was opened by Claude V. Caver in Texas. Caver obtained a permit from the city to project films downtown. With cars parked bumper-to-bumper, patrons witnessed the screening of silent films from their vehicles. In the 1920s, "outdoor movies" became a popular summer entertainment, but few "drive-in" experiments were made due to logistical difficulties; the drive-in theater was patented in Camden, New Jersey by chemical company magnate Richard M. Hollingshead, Jr. whose family owned and operated the R. M. Hollingshead Corporation chemical plant in Camden. In 1932, Hollingshead conducted outdoor theater tests in his driveway at 212 Thomas Avenue in Riverton.
After nailing a screen to trees in his backyard, he set a 1928 Kodak projector on the hood of his car and put a radio behind the screen, testing different sound levels with his car windows down and up. Blocks under vehicles in the driveway enabled him to determine the size and spacing of ramps so all automobiles could have a clear view of the screen. Hollingshead applied for a patent of his invention on August 6, 1932, he was given U. S. Patent 1,909,537 on May 16, 1933. Hollingshead's drive-in opened in New Jersey June 6, 1933, on Admiral Wilson Boulevard in Pennsauken Township, a short distance from Cooper River Park. Rosemont Avenue now runs through, it offered a 40 by 50 ft screen. He advertised his drive-in theater with the slogan, "The whole family is welcome, regardless of how noisy the children are." The first film shown was the Adolphe Menjou film Wife Beware. Failing to make a profit, Hollingshead sold the theater after three years to a Union, New Jersey theater owner who moved the infrastructure to that city, but the concept caught on nationwide.
The April 15, 1934, opening of Shankweiler's Auto Park in Orefield, was followed by Galveston's Drive-In Short Reel Theater, the Pico Drive-In Theater at Pico and Westwood boulevards in Los Angeles and the Weymouth Drive-In Theatre in Weymouth, Massachusetts. In 1937, three more opened in Ohio and Rhode Island, with another 12 during 1938 and 1939 in California, Maine, Massachusetts, New York and Virginia. Early drive-in theaters had to deal with sound issues; the original Hollingshead drive-in had speakers installed on the tower itself which caused a sound delay affecting patrons at the rear of the drive-in's field. In 1935, the Pico Drive-in Theater attempted to solve this problem by having a row of speakers in front of the cars. In 1941, RCA introduced in-car speakers with individual volume controls which solved the noise pollution issue and provided satisfactory sound to drive-in patrons. Just before World War II, 9 of the 15 drive-in movie theaters open in the United States were operated by Philip Smith, who promoted a family-friendly environment by allowing children to enter free and built playgrounds.
The drive-in's peak popularity came in the late 1950s and early 1960s in rural areas, with some 4,000 drive-ins spread across the United States. Among its advantages was the fact that older adults with children could take care of their infant while watching a movie, while youth found drive-ins ideal for a first date. Revenue is more limited than regular theaters. There were abortive attempts to create suitable conditions for daylight viewing such as large tent structures, but nothing viable was developed. During the 1950s, the greater privacy afforded to patrons gave drive-ins a reputation as immoral, they were labeled "passion pits" in the media. Beginning in the 1970s, many drive-ins changed from family fare to exploitation films, as a way to offset declining patronage and revenue. During the 1970s, some drive-ins began to show pornographic movies in less family-centered time slots to bring in extra income; this allowed censored materials to be viewed by a wide audience, some for whom viewing was still illegal in many states, it was reliant upon the whims of local ordinances controlling such material.
It required a remote location distant from populated areas such as towns and cities. During their height, s
A film festival is an organized, extended presentation of films in one or more cinemas or screening venues in a single city or region. Film festivals show some films outdoors. Films may be of recent date and, depending upon the festival's focus, can include international and domestic releases; some festivals focus on genre or subject matter. A number of film festivals specialise in short films of a defined maximum length. Film festivals are annual events; some film historians, including Jerry Beck, do not consider film festivals official releases of film. The most prestigious film festivals in the world are considered to be Cannes and Venice; these festivals are sometimes called the "Big Three." The Toronto International Film Festival is North America's most popular festival in terms of attendance. The Venice Film Festival is the oldest film festival in the world; the Venice Film Festival in Italy began in 1932, is the oldest film festival still running. Raindance Film Festival is the UK's largest celebration of independent film-making, takes place in London in October.
Mainland Europe's biggest independent film festival is ÉCU The European Independent Film Festival, that started in 2006 and takes place every spring in Paris, France. Edinburgh International Film Festival is the longest running festival in Great Britain. Australia's first and longest running film festival is the Melbourne International Film Festival, followed by the Sydney Film Festival. North America's first and longest running short film festival is the Yorkton Film Festival, established in 1947; the first film festival in the United States was the Columbus International Film & Video Festival known as The Chris Awards, held in 1953. According to the Film Arts Foundation in San Francisco, "The Chris Awards one of the most prestigious documentary, educational and informational competitions in the U. S, it was followed four years by the San Francisco International Film Festival, held in March 1957, which emphasized feature-length dramatic films. The festival played a major role in introducing foreign films to American audiences.
Films in the first year included Akira Kurosawa's Throne of Blood and Satyajit Ray's Pather Panchali. Today, thousands of film festivals take place around the world—from high-profile festivals such as Sundance Film Festival and Slamdance Film Festival, to horror festivals such as Terror Film Festival, the Park City Film Music Festival, the first U. S. film festival dedicated to honoring music in film. Film Funding competitions such as Writers and Filmmakers were introduced when the cost of production could be lowered and internet technology allowed for the collaboration of film production. Although there are notable for-profit festivals such as SXSW, most festivals operate on a nonprofit membership-based model, with a combination of ticket sales, membership fees, corporate sponsorship constituting the majority of revenue. Unlike other arts nonprofits, film festivals receive few donations from the general public and are organized as nonprofit business associations instead of public charities.
Film industry members have significant curatorial input, corporate sponsors are given opportunities to promote their brand to festival audiences in exchange for cash contributions. Private parties to raise investments for film projects, constitute significant "fringe" events. Larger festivals maintain year-round staffs engaging in community and charitable projects outside festival season. While entries from established filmmakers are considered pluses by the organizers, most festivals require new or unknown filmmakers to pay an entry fee to have their works considered for screening; this is so in larger film festivals, such as the Cannes Film Festival, Toronto International Film Festival, Sundance Film Festival, South by Southwest, Montreal World Film Festival, smaller "boutique" festivals such as the Miami International Film Festival, British Urban Film Festival in London and Mumbai Women's International Film Festival in India. On the other hand, some festivals—usually those accepting fewer films, not attracting as many "big names" in their audiences as do Sundance and Telluride—require no entry fee.
Rotterdam Film Festival, Mumbai Film Festival, many smaller film festivals in the United States, are examples. The Portland International Film Festival charges an entry fee, but waives it for filmmakers from the Northwestern United States, some others with regional focuses have similar approaches. Several film festival submission portal websites exist to streamline filmmakers' entries into multiple festivals, they provide databases of festival calls for entry and offer filmmakers a convenient "describe once, submit many" service. The core tradition of film festivals is competition, that is, the consideration of films with the intention of judging which are most deserving of various forms of recognition. In contrast to those films, some festivals may screen some films without treating them as part of the competition; the three most prestigious film festivals are considered to be Cannes, B
Digital Light Processing
Digital Light Processing is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device. It was developed in 1987 by Larry Hornbeck of Texas Instruments. While the DLP imaging device was invented by Texas Instruments, the first DLP-based projector was introduced by Digital Projection Ltd in 1997. Digital Projection and Texas Instruments were both awarded Emmy Awards in 1998 for the DLP projector technology. DLP is used in a variety of display applications from traditional static displays to interactive displays and non-traditional embedded applications including medical and industrial uses. DLP technology is used in DLP front projectors, DLP rear projection television sets, digital signs, it is used in about 85% of digital cinema projection, in additive manufacturing as a light source in some printers to cure resins into solid 3D objects. Smaller "pico" chipsets are used in mobile devices including cell phone accessories and projection display functions embedded directly into phones.
In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micromirror Device. These mirrors are so small that DMD pixel pitch may be less; each mirror represents one or more pixels in the projected image. The number of mirrors corresponds to the resolution of the projected image. 800×600, 1024×768, 1280×720, 1920×1080 matrices are some common DMD sizes. These mirrors can be repositioned to reflect light either through the lens or onto a heat sink. Toggling the mirror between these two orientations produces grayscales, controlled by the ratio of on-time to off-time. There are two primary methods by which DLP projection systems create a color image: those used by single-chip DLP projectors, those used by three-chip projectors. A third method, sequential illumination by three colored light emitting diodes, is being developed, is used in televisions manufactured by Samsung. In a projector with a single DLP chip, colors are produced either by placing a color wheel between a white lamp and the DLP chip or by using individual light sources to produce the primary colors, LEDs or lasers for example.
The color wheel is divided into multiple sectors: the primary additive colors: red and blue, in many cases white. Newer systems substitute the primary subtractive colors cyan and yellow for white; the use of the subtractive colors is part of the newer color performance system called BrilliantColor which processes the additive colors along with the subtractive colors to create a broader spectrum of possible color combinations on the screen. The DLP chip is synchronized with the rotating motion of the color wheel so that the green component is displayed on the DMD when the green section of the color wheel is in front of the lamp; the same is true for the red and other sections. The colors are thus displayed sequentially at a sufficiently high rate that the observer sees a composite "full color" image. In early models, this was one rotation per frame. Now, most systems operate at up to 10× the frame rate; the black level of a single-chip DLP depends on. If the unused light is scattered to reflect and dissipate on the rough interior walls of the DMD / lens chamber, this scattered light will be visible as a dim gray on the projection screen, when the image is dark.
Deeper blacks and higher contrast ratios are possible by directing unused HID light away from the DMD / lens chamber into a separate area for dissipation, shielding the light path from unwanted internal secondary reflections. DLP projectors utilizing a mechanical spinning color wheel may exhibit an anomaly known as the "rainbow effect"; this is best described as brief flashes of perceived red and green "shadows" observed most when the projected content features high contrast areas of moving bright or white objects on a dark or black background. Common examples are the scrolling end credits of many movies, animations with moving objects surrounded by a thick black outline. Brief visible separation of the colours can be apparent when the viewer moves their eyes across the projected image; some people perceive these rainbow artifacts while others may never see them at all. This effect is caused by the way; when an object on the screen moves, the eye follows the object with a constant motion, but the projector displays each alternating color of the frame at the same location for the duration of the whole frame.
So, while the eye is moving, it sees a frame of a specific color. When the next color is displayed, although it gets displayed at the same location overlapping the previous color, the eye has moved toward the object's next frame target. Thus, the eye sees that specific frame color shifted; the third color gets displayed, the eye sees that frame's color shifted again. This effect is not perceived only the whole picture. Multi-color LED-based and laser-based single-chip projectors are able to eliminate the spinning wheel and minimize the rainbow effect, since the pulse rates of LEDs and lasers are not limited by physical motion. "Three-chip DLP projectors have no color wheels, thus do not manifest this artifact." A three-chip DLP projector uses a prism to split light from the lamp, each primary col
An LCD projector is a type of video projector for displaying video, images or computer data on a screen or other flat surface. It is a modern equivalent of the slide overhead projector. To display images, LCD projectors send light from a metal-halide lamp through a prism or series of dichroic filters that separates light to three polysilicon panels – one each for the red and blue components of the video signal; as polarized light passes through the panels, individual pixels can be opened to allow light to pass or closed to block the light. The combination of open and closed pixels can produce a wide range of colors and shades in the projected image. Metal-halide lamps are used because they output an ideal color temperature and a broad spectrum of color; these lamps have the ability to produce an large amount of light within a small area. Other technologies, such as Digital Light Processing and liquid crystal on silicon are becoming more popular in modestly priced video projection; because they use small lamps and the ability to project an image on any flat surface, LCD projectors tend to be smaller and more portable than some other types of projection systems.
So, the best image quality is found using a blank white, grey, or black surface, so dedicated projection screens are used. Perceived color in a projected image is a factor of both projection projector quality. Since white is more of a neutral color, white surfaces are best suited for natural color tones. However, darkest black in a projected image is dependent on; because of this, some presenters and presentation-space planners prefer gray screens, which create higher-perceived contrast. The trade-off is. Color problems can sometimes be adjusted through the projector settings, but may not be as accurate as they would on a white background. A projector's throw ratio is used when installing projectors to control the size of the projected display. For example, if the throw ratio is 2:1 and the projector is fourteen feet away from the screen the display width will be seven feet. Early experiments with liquid crystals to generate a video image were done by John A. van Raalte at the RCA-Laboratories in 1968.
His concept was based on e-beam-addressing to generate an electronic charge pattern corresponding to a video image, which in turn controlled the LC layer of a reflective LC cell. Gene Dolgoff began thinking about different types of projectors in college in 1968 as a way to produce a video projector that would be brighter than the then-available CRT projectors; the idea was to use elements referred to as "light valves" to regulate the amount of light that passes through it, such as in traditional slide projectors. This would allow the use of a powerful external light source. After looking at many different materials, he thought that liquid crystals would allow to modulate the light as planned. However, direct-driven, matrix-addressed LCDs with sufficient resolution for video images were not available at the time, so that Dolgoff could not yet complete building his projector prototype; the first experiments with a direct-driven, transmissive matrix-addressed LCD using a converted slide projector by Peter J. Wild working at Brown Boveri Research in Switzerland were conducted in 1971.
A projector was shown at the SID Conference 1972 in San Francisco. As passive LCDs were not capable of displaying images with sufficient resolution for video pictures, a combination of a fixed image together with an LCD matrix for the variable elements was proposed as an LC projector for certain control room applications, with a corresponding patent filed in Switzerland on Dec. 3, 1971. A lot of effort went into optimizing thin-film transistors suitable for driving active matrix-addressed LCDs; the concept was invented and early trials were conducted by teams at RCA and Westinghouse Electric. T Peter Brody founded Panelvision in 1981 to manufacture AM LCDs. Breakthroughs occurred elsewhere in new materials and thin-film structures, with Hitachi of Japan as a pioneering company; such AM LCDs became commercially available in the early 1980s. Therefore, it took Dolgoff until 1984 to get a digitally-addressable LCD matrix device with sufficient resolution and contrast, when he completed building his LCD video projector.
After building it, he saw many problems that had to be corrected including major light losses and noticeable pixels. He invented new optical methods to create efficient and bright projectors and invented depixelization to reduce the screen-door effect. At about the same time, the German company "Bonner Ingenieurbüro für Optoelektronik CrystalVision" started experimenting with LCD projection devices from 1985 onwards. Although traditional slide projectors used infrared filters to reduce heating of the photographic slides, LCDs are much more sensitive to overheating; when the temperature in the nematic liquid crystal layer reaches the "clearing point", the LC light valve does not work anymore until the temperature drops below again. Bernt Haastert, an engineer working at CrystalVision, found out, that placing the required polarizing filters at a certain distance on both sides of the LC cell allowed for efficient air cooling of the arrangement. Without applying this invention, L
An outdoor cinema consists of a digital or analog movie projector, scaffolded construction or inflatable movie screen, sound system. Outdoor cinemas first began at around 1916 in Germany. Viewers sit on camping chairs or blankets; some Hollywood world premieres were screened in outdoor cinemas – sometimes with the stars in attendance. Most screenings are free with some raising money for charities; as projector prices have decreased, guerrilla style outdoor cinemas have become more common. These are run on a small budget by groups of amateurs, it is common for the events to be organised online, participants meet in parks, empty parking lots or other public places. Guerrilla outdoor cinemas are basic needing to be set up and dismantled in a single night. Sheets, portable screens or existing walls are used as a screen for the projected image. Power is obtained from generators or car batteries; these kind of cinemas are popular in Greece during the summer period with at least 90 operating in Athens, as of 2015.
In the Sixties, the city used to host more than 600 outdoor cinemas. Large and well-known outdoor cinemas include the Outdoor Cinema Food Fest in California, Oshkosh’s Fly-In theater, Screen on the Green or Sunset Cinema in Australia. More and more prestigious film festivals add outdoor movies to their regular screenings; some of the most important outdoor movie events were the world premiere of Shark Tale on St. Mark’s Square at Venice Film Festival and outdoor at Dubai International Film Festival. There are more private outdoor cinemas, sometimes as a part of a pool or backyard party. Unusual locations to show a movie outdoors include of skyscraper rooftops, screens floating on a lake with spectators sitting on boats, screenings where guests watch a movie in hot tubs or drive-in cinemas on the top floor of a parking garage. A special type of outdoor cinema is the drive-in theater. In cold weather climates, public film screenings have been projected onto surfaces of snow, in such countries as Finland and Canada.
List of drive-in theaters
A projection screen is an installation consisting of a surface and a support structure used for displaying a projected image for the view of an audience. Projection screens may be permanently installed, as in a movie theater; as in a conference room or other non-dedicated viewing space. Another popular type of portable screens are inflatable screens for outdoor movie screening. Uniformly white or grey screens are used exclusively as to avoid any discoloration to the image, while the most desired brightness of the screen depends on a number of variables, such as the ambient light level and the luminous power of the image source. Flat or curved screens may be used depending on the optics used to project the image and the desired geometrical accuracy of the image production, flat screens being the more common of the two. Screens can be further designed for front or back projection, the more common being front projection systems, which have the image source situated on the same side of the screen as the audience.
Different markets exist for screens targeted for use with digital projectors, movie projectors, overhead projectors and slide projectors, although the basic idea for each of them is much the same: front projection screens work on diffusely reflecting the light projected on to them, whereas back projection screens work by diffusely transmitting the light through them. In the commercial movie theaters, the screen is a reflective surface that may be either aluminized or a white surface with small glass beads; the screen has hundreds of small, evenly spaced holes to allow air to and from the speakers and subwoofer, which are directly behind it. Rigid wall-mounted screens maintain their geometry just like the big movie screens, which makes them suitable for applications that demand exact reproduction of image geometry; such screens are used in home theaters, along with the pull-down screens. Pull-down screens are used in spaces where a permanently installed screen would require too much space; these use painted fabric, rolled in the screen case when not used, making them less obtrusive when the screen is not in use.
Fixed-frame screens provide the greatest level of uniform tension on the screens surface, resulting in the optimal image quality. They are used in home theater and professional environments where the screen does not need to be recessed into the case. Electric screens can be wall ceiling mounted or ceiling recessed; these are larger screens, though electric screens are available for home theater use as well. Electric screens are similar to pull-down screens, but instead of the screen being pulled down manually, an electric motor raises and lowers the screen. Electric screens are raised or lowered using either a remote control or wall-mounted switch, although some projectors are equipped with an interface that connects to the screen and automatically lowers the screen when the projector is switched on and raises it when the projector is switched off. Switchable projection screens can be switched between clear. In the opaque state, projected image on the screen can be viewed from both sides, it is good for advertising on store windows.
Mobile screens use either a pull-down screen on a free stand, or pull up from a weighted base. These can be used when it is impractical to mount the screen to a wall or a ceiling. Both mobile and permanently installed pull-down screens may be of tensioned or not tensioned variety. Tensioned models attempt to keep the fabric flat and immobile, whereas the not tensioned models have the fabric of the screen hanging from their support structures. In the latter screens the fabric can stay immobile if there are currents of air in the room, giving imperfections to the projected image. Specialty screens may not fall into any of these categories; these include inflatable screens and others. See the respective articles for more information. One of the most quoted properties in a home theater screen is the gain; this is a measure of reflectivity of light compared to a screen coated with magnesium carbonate, titanium dioxide, or barium sulfate when the measurement is taken for light targeted and reflected perpendicular to the screen.
Titanium dioxide is a bright white colour, but greater gains can be accomplished with materials that reflect more of the light parallel to projection axis and less off-axis. Quoted gain levels of various materials range from 0.8 of light grey matte screens to 2.5 of the more reflective glass bead screens, some manufacturers claiming higher numbers for their products. High gain levels could be attained by using a mirror surface, although the audience would just see a reflection of the projector, defeating the purpose of using a screen. Many screens with higher gain are semi-glossy, so exhibit more mirror-like properties, namely a bright "hot spot" in the screen—an enlarged reflection of the projector’s lens. Opinions differ as to when this "hot spotting" begins to be distracting, but most viewers do not notice differences as large as 30% in the image luminosity, unless presented with a test image and asked to look for variations in brightness; this is possible because humans have greater sensitivity to contrast in smaller details, but less so in luminosity variations as great as half of the screen.
Other screens with higher gain are semi-retroreflective. Unlike mirrors, retroreflective surfaces reflect light back toward the source. Hot spotting is less of a problem with retroreflectiv
A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a bright light or laser to project the image, most modern ones can correct any curves and other inconsistencies through manual settings. Video projectors are used for many applications such as conference room presentations, classroom training, home cinema and concerts. In schools and other educational settings, they are sometimes connected to an interactive whiteboard. In the late 20th century they became commonplace in home cinema. Although large LCD television screens became quite popular, video projectors are still common among many home theater enthusiasts. A video projector known as a digital projector, may project onto a traditional reflective projection screen, or it may be built into a cabinet with a translucent rear-projection screen to form a single unified display device. Common display resolutions include SVGA, XGA, SXGA+, 720p, 1080p, 4K UHD, as well as 16:10 aspect ratio resolutions including WXGA+ and WUXGA The cost of a projector is driven by its base technology, features and light output.
A projector with a higher light output is required for a larger screen or for a room with a larger amount of ambient light. For example, a light output of 1500 to 2500 ANSI lumens is suitable for small screens viewed in rooms with low ambient light. High brightness large-venue models are common in Boardrooms and other high profile spaces, models up to 30,000 lm are used in large staging applications such as concerts, keynote addresses and displays projected on buildings. A few camcorders have a built-in projector suitable to make a small projection. LCD projector using LCD light gates; this is the simplest system, making it one of the most common and affordable for home theaters and business use. Common problems include a visible “screen door” or pixelation effect, the LCD panels deteriorating from heat & UV rays, leading to discolored spots or holes in the image, although recent advances have reduced the severity of these issues in some models. DLP projector using Texas Instruments’ DLP technology.
This uses two, or three microfabricated light valves called digital micromirror devices. The single- and double-DMD versions use rotating color wheels in time with the mirror refreshes to modulate color; the most common problem with the single- or two-DMD varieties is a visible “rainbow” which some people perceive when moving their eyes. More recent projectors with higher speed and otherwise optimised color wheels have lessened this effect. 3-chip DLP projectors do not have this problem, as they display each primary color and offer higher light output and more accurate color reproduction, however the cost is higher and thus 3-chip DLP technology is used in large venue, high brightness models, as well as Digital Cinema projectors. LCoS projectors; such projectors process light in the Fourier domain, which enables correction of optical aberrations using Zernike polynomials. Some commercially available technologies include: D-ILA JVC’s Direct-drive Image Light Amplifier based on LCoS technology.
SXRD Sony’s proprietary variant of LCoS technology. LED projectors use one of the above-mentioned technologies for image creation, with a difference that they use an array of Light Emitting Diodes as the light source, negating the need for lamp replacement. Hybrid LED and laser diode system developed by Casio. Uses a combination of Light Emitting Diodes and 445 nm laser diodes as the light source, while image is processed with DLP chip. Laser diode projectors have been developed by Aaxa Technologies. Microvision projectors use Microvision's patented MEMS laser beam-steering technology, whereas Aaxa Technologies uses laser diodes + LCoS. Laser projectors are now available from most projector manufacturers, including Barco, Christie Digital, Epson, Hitachi, NEC, Panasonic, Sony and many others; these units use a laser light source, are used with most common projection technologies, including Single & 3-Chip DLP, LCD and LCoS. They offer numerous advantages, including eliminating the high cost and downtime of replacing lamps, variations in brightness and color that occur as lamps age and improved color fidelity.
Typical laser light sources used in projectors are rated for 20,000 hours before the light output is reduced to 50%, whereas lamps lose brightness and need to be replaced after as little as 1000-2000 hours. CRT projector using cathode ray tubes. Once dominated the projection market, but given their limited light output, size and need for complex alignment, they have since been displaced by digital projectors and are no longer being made Eidophor oil-film projectors LIA light valves Schmidt-CRT, developed by Kloss Video Talaria oil-film projectors Some hobbyists build a do-it-yourself projector for low cost, they build their projectors from kits, sourced components, or from scratch, using a television set as a light source. Through the internet, they obtain plans to construct them for classroom use. 3LCD LCD projector C