Lighten up with DLPs

The lowdown on DLP projectors

What is it? A DLP projector is a type of video projection equipment that uses colored light bounced off an array of tiny mirrors to create an image on a screen.

What are the advantages? They are smaller and lighter than LCD projectors in the same price range.

What are the disadvantages? Some people prefer the image produced by LCD projectors.

Who needs it? Organizations that stage visual presentations, particularly when venues change and an employee needs to carry the equipment and set it up.

Must-know info? Although all DLP projectors rely on the same basic components developed by Texas Instruments, manufacturers optimize their projector models to produce the best image for particular applications. Be sure to pick one that fits the intended use. In comparing image quality, keep in mind that LCD images degrade in quality faster than DLP images, so how it looks in the showroom isn't necessarily what you will see after the device has been used for a while.

BenQ America's PB8230 weighs 6.5 pounds, with brightness rated at 2,200 lumens and a 2,000:1 contrast ratio. It's priced at $3,695.

NEC Solutions' LT10, priced at $1,995, weighs in at 2.1 pounds with brightness of 1,100 lumens and a 2,000:1 contrast ratio.

DLP projectors shed weight and gain brightness

According to the old saying, a picture is worth a thousand words. Anyone who has sat through an hour-long lecture without visuals would be quick to agree.

Lightweight Digital Light Processing projectors, as little as 2 pounds and as thin as a laptop, make it easier to take visual presentations on the road. Prices have dropped along with the weight, with units now coming in at under $1,000.

A new generation of devices expected next year reportedly will take portability even further, with battery-powered, wireless personal projectors small enough to slip into your pocket.

'DLP is the clear leader in the smallest-size projectors and is in wide-open competition with LCD on larger conference room projectors,' said Chris Chinnock, a senior analyst for Insight Media in Norwalk, Conn.

DLP is a technology developed by Texas Instruments Inc. of Dallas, which has more than 500 patents covering the subject. The company doesn't sell the finished products, but it sells the components to more than 50 other companies that incorporate them into their own devices.

DLP circuitry has three main components: a Digital Micromirror Device (DMD chip), an ASIC (application-specific integrated circuit) to control the DMD chip, and a light source.

The DMD chip consists of an array of hinged microscopic mirrors. Each of the mirrors is less than one-fifth the width of a human hair. As many as 1.3 million of the mirrors, one for each pixel, reside on a single DMD chip.

In response to an electronic signal, the mirrors tilt to direct the light toward or away from the screen.

Depending on what portion of the time an individual mirror is switched on or off, it can produce any of 1,074 levels of brightness for that pixel.

Projectors provide the light in one of two ways. Smaller devices have a single DMD chip. Between the lamp and the DMD chip is a rapidly spinning color wheel that filters the light into red, green or blue. In this system, only one color is being reflected at one time, but each of these colors is being flashed rapidly enough that it visually blends into a single picture.
Larger projectors, such as those used in theaters, incorporate a three-chip design. White light from the lamp passes through a prism that sends the red, green and blue portions of the spectrum to separate chips for imaging.

Colorful display

The single chip design makes it possible to build smaller, lighter portable devices, while the larger ones are brighter and offer more subtle color accuracy'35 trillion colors compared to the 16.7 million available from a single chip.

'Our guidelines are to use a single chip for up to 5,000 lumens, and three chips beyond that,' said Frank Moizio, business development manager for Texas Instruments' DLP business products. 'Three-chip devices offer excellent contrast ratios and color quality with brightness up to 25,000 lumens.'

DLP projectors range in size from theater and stadium applications down to 2-pound portables. DLP leads the market for small units because, since they have single chips while LCDs require three chips, the smallest DLP units are half the weight of the smallest LCD projectors.

At the other end of the spectrum, DLP projectors go up to 25,000 lumens, while LCDs peak at 10,000.

Approximately 30 companies manufacture DLP projectors, but the top two account for more than half the units sold. InFocus Corp. leads with 30.7 percent of the market. Dell Inc. follows at 20.1 percent.

While the basic technology of DMD chips is established, Texas Instruments has continued to boost the resolution of its units and now produces up to 1,050 by 1,400 pixels on a single chip. Last year it introduced a refinement called Dark Chip 2 that raises the contrast ratio'a key factor in image clarity'up to 2,000:1, far better than the 400:1 or 800:1 found on LCD projectors.

'The push in the market for the last 10 years has been more pixels, more brightness and a smaller platform,' Chinnock said. 'The image quality is pretty much there, so we are now shifting more toward the feature set'better video performance, wireless connectivity, networkability and improved user interface.'

Texas Instruments also released a new version of its ASIC, the DDP 2000, which incorporates many of the functions that required additional components on the chip. This includes better video processing to produce smoother moving images, on-screen display functions and other features.

The next big news will be pocket-sized devices, expected next year. BenQ America Corp. and Optoma Technology Inc. are developing devices that use LEDs rather than light bulbs. They will only have an output of around 50 lumens, so you wouldn't use them in a conference room. But they may be small enough to fit into a smart phone or personal digital assistant, freeing mobile users from their tiny displays.

Drew Robb of Glendale, Calif., writes about IT.


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