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Encyclopedia > LCD 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 analog of the slide projector or overhead projector. Projected image from a video projector in a home cinema. ... [carousel slide projector, the most common form of projector] A slide projector is an opto-mechanical device to view photographic slides. ... An overhead projector is a display system that is used to display images to an audience. ...

Contents

Overview

To display images, LCD (liquid crystal display) projectors typically send light from a Metal halide lamp through a prism that seperates light to three poly silicone panels -- one each for the red, green, and blue components of the video signal. As polarised light passes through the panels (combination of polarizer, LCD panel and analyzer), 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. LCD redirects here. ... Example of a light source using a broad spectrum metal halide lamp pointing upward towards the sky. ...


Metal Halide lamps are used because they output an ideal color temperature and a broad spectrum of color. These lamps also have the ability to produce an extremely large amount of light within a small area: current projectors average about 2,000-4,000 ANSI lumens. The lumen (symbol: lm) is the SI unit of luminous flux. ...


Newer technologies, such as DLP and LCOS are becoming more popular in video projection. In practice, the term "LCD Projector" is often used as a catch-all for any type of computer projector, regardless of the technology being used. This article is about Digital Light Processing. ... Liquid crystal on silicon (LCOS or LCoS) is a micro-projection or micro-display technology typically applied in projection televisions. ...


Projection surfaces

Thanks to small Metal Halide lamps and the ability to project an image on any flat surface, LCD projectors tend to be smaller and more portable than other types of projection systems. Even so, the best image quality is found using a blank white or grey surface, so dedicated projection screens are often used. Home theater projection screen (119 in. ...


Perceived color in a projected image is a factor of both projection surface and projector quality. Since white is more of a neutral color, white surfaces are best suited for natural color tones; as such, white projection surfaces are more common in most business and school presentation environments.


However, darkest black in a projected image is dependent on how dark the screen is. Because of this, some presenters and presentation space planners prefer gray screens, which create higher perceived contrast. The trade-off is that darker backgrounds can throw off color tones. Color problems can sometimes be adjusted through the projector settings, but may not be as accurate as they would on a white background.


History

Early LCD systems were used with existing overhead projectors. The LCD system did not have a light source of its own: it was built on a large "plate" that sat on top of the projector in place of the transparencies. This provided a stop-gap solution in the era when the computer was not yet the universal display medium, creating a market for LCD projectors before their current main use became popular.


This technology is employed in some sizes of rear projection television consoles, as there are cost advantages when employed in mid size sets (40 to 50 inch diagonal). This is not expected to have much longevity in the "home theater" marketplace due to expected improvements cost/performance of competing technologies, particularly in direct-view LCD panels at the lower range of sizes and DLP projection in the larger sizes.[verification needed] Another advantage of using this LCD projection system in large television sets is to allow better image quality as opposed to a single 60 inch television, although currently an equal of an LCD projector is the LG 100 inch LCD TV, still in prototype stages this TV is a huge advancement towards projector sized televisions. A common rule of thumb is that an LCD's image quality will decrease with a size increase. A workaround is to use a small lcd panel (or panels) and project them through a lens onto a rear projection screen to give a larger screensize (with a decreased contrast ratio) but without the quality loss. This article is about Digital Light Processing. ...


In 2004 and 2005, LCD front projection has been enjoying a come-back because of the addition of the dynamic iris which has improved perceived contrast up to the levels of DLP. This article is about Digital Light Processing. ...


The basic design of an LCD projector is frequently used by hobbyists who build their own DIY projection systems. The basic technique is to combine a high CRI HID lamp and ballast with a condenser and collector fresnel, an LCD removed from a common computer display and a triplet. See also: DIY Network, a cable TV network. ... The Color Rendering Index (CRI) (sometimes called Color Rendition Index), is a measure of the ability of a light source to reproduce the colors of various objects being lit by the source. ... 15 kW Xenon short-arc lamp used in IMAX projectors High-intensity discharge (HID) lamps include these types of electrical lamps: mercury vapor, metal halide (also HQI), high-pressure sodium (Son), low-pressure sodium (Sox) and less common, xenon short-arc lamps. ... Not to be confused with Fresnel lantern. ... In physics, spin is the angular momentum intrinsic to a body, as opposed to orbital angular momentum, which is the motion of its center of mass about an external point. ...


See also

A CRT projector is a video projector that uses a small, high-brightness CRT (or picture tube) as the image generating element. ... Projectors are used for displaying an image on a projection screen or similar surface for the view of an audience. ... This is a comparison of various properties of different display technologies. ...

External links


  Results from FactBites:
 
LCD Projector Rentals (793 words)
From boardroom to concert hall, 1,000 to 10,000 lumens, we have a projector to fit your budget.
LCD Projector Rentals.com has projectors in stock and ready to rent to you,
We are LCD Projector Rentals.com a division of Astoria Communications, Inc.
LCD projector - Wikipedia, the free encyclopedia (385 words)
They are the modern equivalent to the slide projector and overhead projector used in the past.
LCD (liquid crystal display) projectors usually contain three separate LCD glass panels, one each for the red, green, and blue components of the video signal.
As light passes through the LCD panels, individual pixels can be opened to allow light to pass, or closed to block the light, as if each little pixel were fitted with a Venetian blind.
  More results at FactBites »

 
 

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