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

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.

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

This article contains content that is written like an advertisement. Please help improve it by removing promotional content and inappropriate external links, and by adding encyclopedic content written from a neutral point of view. (May 2020) (Learn how and when to remove this message)
A Zenith Electronics 1200 CRT-projector-based home theater, ca. 2006

Obsolete technologies

Do-it-yourself video projectors

Some hobbyists build a do-it-yourself (DIY) projector for low cost. They build their projectors from kits, sourced components, or from scratch, using a television set as a light source or a cellphone screen and LED lighting.[15] Through the internet, they obtain plans to construct them[16] for domestic and classroom use.

See also

References

  1. ^ Charles Proctor (January 18, 2007). "Christmas is a time for taking -- from schools". Los Angeles Times. Retrieved 2010-11-26.
  2. ^ https://www.toledoblade.com/local/education/2022/06/11/educational-technology-smartboard-trend-losing-traction/stories/20220611123
  3. ^ https://www.boxofficepro.com/lg-odeon-multicines-open-worlds-first-100-percent-led-cinema-dolby-atmos-madrid/
  4. ^ https://www.hollywoodreporter.com/business/digital/led-screens-samsung-sony-lg-1235374322/
  5. ^ https://www.avinteractive.com/news/displays/word-first-acoustic-transparent-led-cinema-screen-debuts-03-07-2024/
  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.