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Home Theater Projector Technology Decoded

April 22, 2013 | Comments

Home theater beckons. You're ready to start mapping out plans for a private movie palace built around a screen that's at least twice the size of your average TV. Your goal is to create an authentic theater experience, which means you're going to need a video projector to fill that screen.

Problem is, apart from knowing that you want the best (1080p) high-definition experience, you know nothing about projectors. And even though you plan to hire a professional home theater designer/installer, you want to learn some of the key lingo. Consider this your cheat sheet.

LCD vs. DLP vs. LCOS Projectors

Most of today's projectors use one of three digital technologies: LCD (liquid crystal diode), DLP (digital light processing - developed and trademarked by Texas Instruments) or LCOS (liquid crystal on silicon), which is marketed under proprietary names like D-ILA (JVC) and SXRD (Sony). All projectors employ a single-lens light source and one or more imaging chips but differ in the way they work.

DLP

The heart of a DLP projector is a micromirror device (DMD) with around 2 million hinged microscopic mirrors that tilt toward the light source (on) or away from it (off) to create a light or dark pixel on the screen. Remarkably, each mirror switches on and off up to thousands of times per second, creating a thousand shades of gray. Light from the projector's lamp passes through a synchronized color filter (or color wheel) with red, green, and blue segments to produce a full range of colors.

The color wheel makes single-chip DLP projectors prone to the "rainbow effect," a fleeting flash of rainbow-like color in that's most visible in scenes with dark and light elements; some people are sensitive to it and others don't see it at all. Generally speaking, DLP projectors do a better job handling motion than LCOS, but contrast isn't quite as good. The most expensive DLP projectors, which produce very bright images and tend to be used in commercial venues and high-end home theaters, use three chips - one for each primary color - instead of a single chip and color wheel.

LCOS

LCOS projectors use "micro-display" technology that's similar to DLP projectors but use liquid crystals instead of mirrors; crystals are applied to the surface of a silicon chip coated with a reflective aluminum layer.

There is less space between pixels with LCOS-produced images than with DLP and LCD, which translates into excellent contrast. "White-field uniformity" - subtle hints of color in places where there should be no color - can be an issue with some LCOS models and is caused by misaligned color panels.

LCD

LCD projectors fall on the lower end of the price spectrum, with picture quality that lags behind DLP and LCOS. Light from a lamp passes through a prism or series of filters that separates it into three panels - one each for red, green and blue. As polarized light passes through the panels, individual pixels are opened to pass light or closed to block it, which produces a full range of colors and shades in the projected image.

LED

LED projectors, which are relatively new to the scene, use LEDs as a light source instead of a lamp. They're far more expensive than lamp-based competitors, but LEDs will likely last as long as the projector itself. Current-generation models tend to produce dimmer images than lamp projectors, which could be a concern with very large screens.

The Bottom Line

Each technology is capable of producing excellent quality images, so it will come down to budget and personal preference. And professional designers/installers will usually recommend one technology or another based on their experience. Learning the basics of video projectors will make you more confident throughout the decision-making process. Click here for a list of CEDIA-member home technology professionals in your area.