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LCD Projectors

LCD projectors are ideal for home and business.

LCD projectors can be used for business. [©Jupiter Images, 2010]
©Jupiter Images, 2010
LCD projectors can be used for business.

LCD Projectors

Liquid crystal display projectors, or LCD projectors, use the same technology as the screens on cell phones and MP3 players. LCD technology permits electronic devices to be thinner and lighter in weight while drawing less power than competing display technologies. LCD projectors produce bright, crisp, naturally colored, easy-to-see images and detailed shadows. They can project spreadsheet data and PowerPoint slides in business presentations and TV shows and movies in home theaters. An LCD projector offers a reliable, sophisticated and universally appealing technology.

How LCD Projectors Work

LCD projectors use a three-panel liquid crystal display (3LCD) system that relies on one or more lamps to project images onto a wall or screen. The lamps contain either high-pressure mercury vapor or xenon gas and project images from a computer or video disc player. A pair of dichroic mirrors split the white light from the lamps into beams of specific red, green and blue wavelengths. Each beam passes through an LCD panel made up of thousands of pixels. Electrical currents switch the pixels on or off to create the color's grayscale equivalent; the three component colors then pass through a prism that recombines them into the image projected through the lens onto the screen.

Image Resolution of LCD Projectors

Combining three liquid crystal displays lets LCD projectors project images with billions of colors and smooth grayscale gradations. The quality, or resolution, of the images is determined by the number of pixels composing the LCD panel that the light passes through. High-definition LCD projectors use a grid of 1920 by 1080 pixels (1080p), while budget home theater LCD projectors use a 1280 by 720 (720p) grid. Some newer grids promise resolutions up to 3840 by 2160 (4K).

LCD projectors used to project business data employ one of the following resolution standards:

  • UXGA (1600 by 1200)
  • SXGA (1280 by 1024) or SXGA+ (1400 by 1050)
  • WXGA (1280 by 768)
  • XGA (1024 by 768)
  • SVGA (800 by 600)

Most business presentations can get by with the lower resolutions. Presentations that require greater viewing detail, such as engineering drawings or digital photographs, are best projected with an SXGA or better projector. In general, the projector resolution should match that of the computer connected to it.

Aspect Ratio of LCD Projectors

An LCD projector's aspect ratio is the ratio of the image's horizontal length to its vertical height. The 4-3 (1.33-to-1) aspect ratio of standard almost-square television screens means that the displayed image is 4 units wide for every 3 units high. Horizontally wider high-definition television screens have a 16-9 (1.78-to-1) aspect ratio. Most LCD projectors use one of these two aspect ratios, although a super-widescreen (Cinemascope or letterbox) format with a 2.35-1 ratio is available and is suited for viewing movies shot in that format.

A 4-3 aspect ratio works best for viewing normal-definition television programs and movies made before 1953, which were shot in that format. However, the advent of high-definition television has made the 16-9 aspect ratio the favorite choice for both LCD projectors and the format of the content they project. Such projectors include horizontal stretch options to expand 4-3 images to the 16-9 format and can be fitted with an external anamorphic lens to project super-widescreen movies, offering better image quality than 4-3 aspect ratio projectors.

Brightness and Contrast of LCD Projectors

An LCD projector's brightness refers to its light output. A home theater LCD projector should be bright enough to fill the screen with good contrast but not bright enough to hurt the viewer's eyes. A business LCD projector should be bright enough to display the application screen clearly and should be made brighter in settings where there are large numbers of people taking notes on what is presented. Also, projecting onto a wall requires a brighter projector, while a highly reflective screen requires a less-bright projector.

Contrast represents the difference in brightness between the whitest white and blackest black in an image. The greater this difference, the higher the contrast. High-contrast projectors can make 2-D images look almost 3-D, with good shadow definition and deep color saturation. Contrast ratios may be determined solely from the difference between the whitest white and blackest black (the on/off contrast) or by analyzing individual squares in a black-and-white checkerboard pattern (ANSI contrast). Typical contrast ratios are 2000-to-1, 5000-to-1 and 10000-to-1; an LCD projector that prefaces this number with the words up to includes a dynamic iris that opens or closes in response to the brightness of the projected image.

In LCD projectors used for business purposes, brightness (light output) is more important than contrast, but for home theater projectors, contrast is much more important than brightness. Portable projectors weighing 7 pounds or less that are designed to be carried from presentation to presentation may not be as bright as those weighing 10 to 15 pounds.

Special Features of LCD Projectors

Many LCD projectors offer zoom lenses and physical lens shift to make it easier to adapt the projectors to a variety of room layouts and screen sizes. Zoom lenses let the projector display the desired-size image from a range of distances from the screen. The higher the first number in the zoom ratio, the greater the range; however, too great a zoom range causes dimmer images at the upper end of the range. Lens shift lets the lens be moved up, down, left or right without tilting the projector. Horizontal lens shift is available from 5 to 50 percent of an image's width, while vertical shift is available in a wider percentage range of an image's height. LCD projectors for businesses may also offer keystone correction, which corrects image distortion caused when the screen is not perpendicular to the line of projection, and multiple input jacks for when more than one computer is connected to the projector.

Finding an LCD Projector

LCD projectors can be purchased from business supply or home electronics stores as well as online. According to Projector Central, most 720p home theater projectors run from $1,000 to $4,000, with higher-end 1080p models exceeding that price and low-end 480p models available for under $1,000. People with the know-how can build their own LCD projector for under $300, according to Audiovisualizers.com.

The projector lamp is the greatest maintenance expense after purchase. According to Projector Reviews, lamps for most projectors cost $299 to $449; however, the cost of replacing the lamps on high-end multiple lamp units can run over $1,000. Most lamps last a maximum of 2,000 hours at full power or 3,000 hours at low power. It may be wise to have a replacement lamp readily available as a backup.

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