Video projector

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A projector in a standard form factor: The PG-D2870 projector from Sharp, which uses Digital Light Processing technology Projektor PGD2870W firmy Sharp.jpg
A projector in a standard form factor: The PG-D2870 projector from Sharp, which uses Digital Light Processing technology
An image from a video projector in a home cinema Projection-screen-home2.jpg
An image from a video projector in a home cinema

A video projector is an image projector that receives a video signal and projects the corresponding image onto a projection screen using a lens system. Video projectors use a very bright ultra-high-performance lamp (a special mercury arc lamp), Xenon arc lamp, metal halide lamp, LED or solid state blue, RB, RGB or fiber-optic lasers to provide the illumination required to project the image. Most modern projectors can correct any curves, blurriness and other inconsistencies through manual settings.

Contents

Video projectors are used for many applications such as conference room presentations, classroom training, home cinema, movie theaters, and concerts, having mostly replaced overhead, slide and conventional film projectors. In schools and other educational settings, [1] 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. In some applications, video projectors have been replaced with large monitors or LED screens, [2] or their replacement has been explored. [3] [4] [5]

Overview

A video projector, also 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 (800×600 pixels), XGA (1024×768 pixels), SXGA+ (1400×1050 pixels), 720p (1280×720 pixels), and 1080p (1920×1080 pixels), 4K UHD (3840×2160), as well as 16:10 aspect ratio resolutions including WXGA+ (1280×800 pixels) and WUXGA (1920×1200 pixels).

If a blue laser is used, a phosphor wheel is used to turn blue light into white light, which is also the case with white LEDs. (White LEDs do not use lasers.) A wheel is used in order to prolong the lifespan of the phosphor, as it is degraded by the heat generated by the laser diode. Remote fiber-optic RGB laser racks can be placed far away from the projector, and several racks can be housed in a single, central room. Each projector can use up to two racks, and several monochrome lasers are mounted on each rack, the light of which is mixed and transmitted to the projector booth using optical fibers. [6] [7] [8] Projectors using RB lasers use a blue laser with a phosphor wheel in conjunction with a conventional solid-state red laser.

The cost of a projector is typically driven by its base technology, features, resolution and light output. A projector with a higher light output (measured in lumens) is required for a larger screen or for a room with more ambient light. [9] For example, a light output of approximately 1500 to 2500 ANSI lumens is suitable for small screens viewed in rooms with low ambient light; approximately 2500 to 4000 lm is suitable for medium-sized screens with some ambient light; over 4000 lm is needed for very large screens or use in rooms with no lighting control such as conference rooms. High brightness large-venue models are increasingly common in boardrooms, auditoriums and other high-profile spaces, and models up to 75,000 lm [10] are used in large staging applications such as concerts, keynote addresses and displays projected on buildings. Video projectors can have a mechanism similar to local backlight dimming to achieve higher contrast ratios by using 6 DLP chips: 3 for display, and 3 for local dimming. [11] [12]

A few camcorders have a built-in projector suitable to make a small projection; a few more powerful "pico projectors" are pocket-sized, and many projectors are portable.

Projection technologies

A Zenith Electronics 1200 CRT-projector-based home theater, ca. 2006 Kalht 01.jpg
A Zenith Electronics 1200 CRT-projector-based home theater, ca. 2006

Obsolete technologies

Do-it-yourself video projectors

Some hobbyists build do-it-yourself (DIY) projectors at low costs. They build their projectors from kits, sourced components, or from scratch, using a television set, cellphone screen, or LED lighting as a light source. [15] DIY construction plans can be obtained through the internet [16] for domestic and classroom use.

See also

Related Research Articles

<span class="mw-page-title-main">Digital cinema</span> Use of digital projectors in cinemas

Digital cinema refers to the adoption of digital technology within the film industry to distribute or project motion pictures as opposed to the historical use of reels of motion picture film, such as 35 mm film. Whereas film reels have to be shipped to movie theaters, a digital movie can be distributed to cinemas in a number of ways: over the Internet or dedicated satellite links, or by sending hard drives or optical discs such as Blu-ray discs.

<span class="mw-page-title-main">LCD projector</span> Type of video projector

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 projector or overhead projector. To display images, LCD projectors typically 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, green 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.

<span class="mw-page-title-main">Gamut</span> Color reproduction capability

In color reproduction and colorimetry, a gamut, or color gamut, is a convex set containing the colors that can be accurately represented, i.e. reproduced by an output device or measured by an input device. Devices with a larger gamut can represent more colors. Similarly, gamut may also refer to the colors within a defined color space, which is not linked to a specific device. A trichromatic gamut is often visualized as a color triangle. A less common usage defines gamut as the subset of colors contained within an image, scene or video.

Liquid crystal on silicon is a miniaturized reflective active-matrix liquid-crystal display or "microdisplay" using a liquid crystal layer on top of a silicon backplane. It is also known as a spatial light modulator. LCoS initially was developed for projection televisions, but has since found additional uses in wavelength selective switching, structured illumination, near-eye displays and optical pulse shaping.

<span class="mw-page-title-main">Film recorder</span> Device that copies content from a computer system to film stock

A film recorder is a graphical output device for transferring images to photographic film from a digital source. In a typical film recorder, an image is passed from a host computer to a mechanism to expose film through a variety of methods, historically by direct photography of a high-resolution cathode-ray tube (CRT) display. The exposed film can then be developed using conventional developing techniques, and displayed with a slide or motion picture projector. The use of film recorders predates the current use of digital projectors, which eliminate the time and cost involved in the intermediate step of transferring computer images to film stock, instead directly displaying the image signal from a computer. Motion picture film scanners are the opposite of film recorders, copying content from film stock to a computer system. Film recorders can be thought of as modern versions of Kinescopes.

<span class="mw-page-title-main">Digital light processing</span> Set of chipsets

Digital light processing (DLP) is a set of chipsets based on optical micro-electro-mechanical technology that uses a digital micromirror device. It was originally 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 also non-traditional embedded applications including medical, security, and industrial uses.

Flicker is a visible change in brightness between cycles displayed on video displays. It applies to the refresh interval on cathode-ray tube (CRT) televisions and computer monitors, as well as plasma computer displays and televisions.

<span class="mw-page-title-main">Television set</span> Device for viewing computers screen and shows broadcast through satellites or cables

A television set or television receiver is an electronic device for viewing and hearing television broadcasts, or as a computer monitor. It combines a tuner, display, and loudspeakers. Introduced in the late 1920s in mechanical form, television sets became a popular consumer product after World War II in electronic form, using cathode-ray tube (CRT) technology. The addition of color to broadcast television after 1953 further increased the popularity of television sets in the 1960s, and an outdoor antenna became a common feature of suburban homes. The ubiquitous television set became the display device for the first recorded media for consumer use in the 1970s, such as Betamax, VHS; these were later succeeded by DVD. It has been used as a display device since the first generation of home computers and dedicated video game consoles in the 1980s. By the early 2010s, flat-panel television incorporating liquid-crystal display (LCD) technology, especially LED-backlit LCD technology, largely replaced CRT and other display technologies. Modern flat-panel TVs are typically capable of high-definition display and can also play content from a USB device. In the late 2010s, most flat-panel TVs began offering 4K and 8K resolutions.

An output device is any piece of computer hardware that converts information or data into a human-perceptible form or, historically, into a physical machine-readable form for use with other non-computerized equipment. It can be text, graphics, tactile, audio, or video. Examples include monitors, printers, speakers, headphones, projectors, GPS devices, optical mark readers, and braille reader.

<span class="mw-page-title-main">Handheld projector</span> Image projector in a handheld device

A handheld projector is an image projector in a handheld device. It was developed as a computer display device for compact portable devices such as mobile phones, personal digital assistants, and digital cameras, which have sufficient storage capacity to handle presentation materials but are too small to accommodate a display screen that an audience can see easily. Handheld projectors involve miniaturized hardware, and software that can project digital images onto a nearby viewing surface.

The grating light valve (GLV) is a "micro projection" technology that operates using a dynamically adjustable diffraction grating. It competes with other light valve technologies such as Digital Light Processing (DLP) and liquid crystal on silicon (LCoS) for implementation in video projector devices such as rear-projection televisions. The use of microelectromechanical systems (MEMS) in optical applications, which is known as optical MEMS or micro-opto-electro-mechanical structures (MOEMS), has enabled the possibility to combine the mechanical, electrical, and optical components in tiny-scale.

<span class="mw-page-title-main">CRT projector</span> Older type of video projector that uses small, high intensity CRTs as image generating elements

A CRT projector is a video projector that uses a small, high-brightness cathode ray tube (CRT) as the image generating element. The image is then focused and enlarged onto a screen using a lens kept in front of the CRT face. The first color CRT projectors came out in the early 1950s. Most modern CRT projectors are color and have three separate CRTs, and their own lenses to achieve color images. The red, green and blue portions of the incoming video signal are processed and sent to the respective CRTs whose images are focused by their lenses to achieve the overall picture on the screen. Various designs have made it to production, including the "direct" CRT-lens design, and the Schmidt CRT, which employed a phosphor screen that illuminates a perforated spherical mirror, all within an evacuated cathode ray tube.

<span class="mw-page-title-main">Christie (audiovisual company)</span>

Christie is an audiovisual company that specializes in digital projection and projection tools for cinema and enterprise markets, video walls, content management, image processing, video wall processors, and SDVoE technology. The company has been granted over 100 patents.

Fulldome refers to immersive dome-based video display environments. The dome, horizontal or tilted, is filled with real-time (interactive) or pre-rendered (linear) computer animations, live capture images, or composited environments.

Laser color television, or laser color video display, is a type of television that utilizes two or more individually modulated optical (laser) rays of different colors to produce a combined spot that is scanned and projected across the image plane by a polygon-mirror system or less effectively by optoelectronic means to produce a color-television display. The systems work either by scanning the entire picture a dot at a time and modulating the laser directly at high frequency, much like the electron beams in a cathode ray tube, or by optically spreading and then modulating the laser and scanning a line at a time, the line itself being modulated in much the same way as with digital light processing (DLP).

<span class="mw-page-title-main">Large-screen television technology</span> Technology rapidly developed in the late 1990s and 2000s

Large-screen television technology developed rapidly in the late 1990s and 2000s. Prior to the development of thin-screen technologies, rear-projection television was standard for larger displays, and jumbotron, a non-projection video display technology, was used at stadiums and concerts. Various thin-screen technologies are being developed, but only liquid crystal display (LCD), plasma display (PDP) and Digital Light Processing (DLP) have been publicly released. Recent technologies like organic light-emitting diode (OLED) as well as not-yet-released technologies like surface-conduction electron-emitter display (SED) or field-emission display (FED) are in development to supersede earlier flat-screen technologies in picture quality.

<span class="mw-page-title-main">Rear-projection television</span> Type of large-screen television display technology

Rear-projection television (RPTV) is a type of large-screen television display technology. Until approximately 2006, most of the relatively affordable consumer large screen TVs up to 100 in (250 cm) used rear-projection technology. A variation is a video projector, using similar technology, which projects onto a screen.

<span class="mw-page-title-main">Digital micromirror device</span> Mirror-based electronic display technology

The digital micromirror device, or DMD, is the microoptoelectromechanical system (MOEMS) that is the core of the trademarked Digital Light Processing (DLP) projection technology from Texas Instruments (TI). The device is used in digital projectors and consists of an array of millions of microscopic mirrors which can be individually tilted many thousand times per second, thereby creating the pixels of the projected images.

Electrically operated display devices have developed from electromechanical systems for display of text, up to all-electronic devices capable of full-motion 3D color graphic displays. Electromagnetic devices, using a solenoid coil to control a visible flag or flap, were the earliest type, and were used for text displays such as stock market prices and arrival/departure display times. The cathode ray tube was the workhorse of text and video display technology for several decades until being displaced by plasma, liquid crystal (LCD), and solid-state devices such as thin-film transistors (TFTs), LEDs and OLEDs. With the advent of metal–oxide–semiconductor field-effect transistors (MOSFETs), integrated circuit (IC) chips, microprocessors, and microelectronic devices, many more individual picture elements ("pixels") could be incorporated into one display device, allowing graphic displays and video.

<span class="mw-page-title-main">3LCD</span> LCD projection color image generation technology

3LCD is the name and brand of a major LCD projection color image generation technology used in modern digital projectors. 3LCD technology was developed and refined by Japanese imaging company Epson in the 1980s and was first licensed for use in projectors in 1988. In January 1989, Epson launched its first 3LCD projector, the VPJ-700.

References

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  2. "Interactive whiteboard projectors fading from classrooms". The Blade. Retrieved 2024-08-01.
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  4. Giardina, Carolyn (2023-04-15). "LED Screens for Theaters: Is the Buzzy Tech Worth the Cost?". The Hollywood Reporter. Retrieved 2024-08-01.
  5. "'Word-first' acoustic transparent LED cinema screen debuts". AV Magazine. Retrieved 2024-08-01.
  6. "Christie 6P laser lights CGV's biggest screen in South Korea" . Retrieved 2023-12-28.
  7. "Christie RGB laser projection" (PDF). Retrieved 2023-12-28.
  8. "Novel laser sources for large-venue projection markets".
  9. Richard Cadena (2006). Automated Lighting: The Art and Science of Moving Light in Theatre, Live Performance, Broadcast, and Entertainment. Focal Press. p. 344. ISBN   978-0-240-80703-4.
  10. "Barco XDL-4K75 DLP Projector".
  11. "Christie to Sell Breakthrough Eclipse HDR Projector for Home Theaters".
  12. "Best Home Theater Projector of All Time? Meet the Christie Eclipse".
  13. Kaczorowski, Andrzej; Gordon, George S.; Palani, Ananta; Czerniawski, Stanislaw; Wilkinson, Timothy D. (2015). "Optimization-Based Adaptive Optical Correction for Holographic Projectors". Journal of Display Technology. 11 (7): 596–603. Bibcode:2015JDisT..11..596K. doi:10.1109/JDT.2015.2418436. S2CID   24142134.
  14. "What's the difference between laser phosphor and RGB laser?". www.barco.com. Retrieved 2023-06-24.
  15. DIY Perks. "Building a TRUE 4k home cinema projector". Youtube. Retrieved 23 August 2023.
  16. Völkel, Frank (November 14, 2004). "Supersize Your TV for $300: Build Your Own XGA Projector!". Tom's Hardware. Archived from the original on 2010-12-29. Retrieved 2022-12-27.