by John McKeon

A big, bright screen image displaying hymn texts, scriptural verses, or live video, is a common part of worship services in thousands of American churches today. All over the country, media ministers are considering either adding or upgrading their display technology.

As they do so, they face an ever more complex array of options, each with its own advantages and drawbacks. Do you want a projector or a panel display of some kind? A projector? Rear-projection or front? How bright, with how much resolution?

The answers require a thorough understanding of each church's individual needs, as well as some fundamentals of projection and display technology.

Projector choices
These days the choice of a projector usually boils down to LCD (Liquid Crystal Display) or DLP (Digital Light Processing). Several new technologies are emerging, however, to contend for shares of the market. Among these are projectors using the D-ILA (Direct-Drive Image Light Amplifier) technology developed by JVC, and a variety of products using LCoS, or Liquid Crystal on Silicon. Both are relatively recent developments, likely to account for a growing number of product offerings in the years ahead. At present, though, most buyers still focus on DLP or LCD projectors.

The core of an LCD or Liquid Crystal Display projector is a panel of LCD pixels. Light from a very bright lamp is directly through the panel, in which each individual pixel can be turned on or off to create the necessary mix of red, green and blue components.

LCD projection has steadily gained resolution and brightness over the years, but it has made this progress in the face of several technological obstacles. In order to increase resolution it's necessary to add pixels, which increases the density of the panel through which light must pass. So higher resolution means bigger lamps, which means more heat, which means larger fans, more weight and more noise.

Manufacturers have evolved their own solutions to this complex equation, seeking to meet customers' demands for portability, brightness, resolution, lamp life and quiet operation. The market today abounds in LCD projectors.

Since 1996,many of the headlines in the projector business have been created by DLP. DLP was introduced at the Infocomm International trade show that year by Texas Instruments, which developed the technology and licensed it to manufacturers. DLP projectors are now plentiful, marketed by numerous companies.

DLP differs from LCD in that DLP chips reflect light rather than transmitting it. At the heart of DLP is a chip called a Digital Micromirror Device, a silicon wafer on which hundreds of thousands of tiny mirrors are mounted.

For SVGA display resolution (800 x 600 pixels), at least 480,000 mirrors are needed. (Actually, SVGA DLP chips use nearly 600,000 micromirrors for this resolution.) Each mirror is hinged and connected to a circuit, so that it can change position either to reflect light into the projector's optical system (the "on" position) or not to reflect. The micromirrors can tilt through a 20-degree range of movement and switch back and forth at incredible speeds.

Three different basic designs were developed for DLP projection engines, using one, two or three "chips." In practice, the choice quickly boiled down to single-chip or three-chip designs.

The three-chip machines, the top of the DLP line, devote a separate DMD chip to each of the three projection colors, red, green and blue. These are the projectors driving the move to digital cinema and being installed in large venues all over the world. They're made by companies like Digital Projection, Inc., Christie Digital Systems (formerly Electrohome), Barco Projection Products, and others.

High brightness and resolution, though, comes a hefty price tag-prices above $100,000 are not unusual.

At the far end of the spectrum, the one-chip DLP design has become nearly ubiquitous, powering light, bright and flexible projectors from many manufacturers.

In a one-chip DLP engine, a spinning wheel of filters enables the single array of mirrors to generate red, green and blue light in a very rapid sequence. This technology has proven more than ample for conference rooms, traveling sales people and trainers, and others. Costs, too, can be quite modest for one-chip DLPs.

But across much of the size and price range, DLPs compete directly with LCD projectors, and church media managers facing this choice have a lot to weigh.

Comparing LCD with DLP
"LCDs are gaining ground in picture quality and brightness, especially for shorter throw distances," notes Wayne Wagner of Wagner Media in Houston, Texas. (Throw distance is the distance from projector to screen.) However, Wagner adds, over longer throw distances LCD projectors can lose half of their light output en route to the screen. "With DLP you can project from up to 15 times screen width and still have 93 percent of the original light."

Steve Thorburn, a partner in a/v systems integrator Thorburn Associates, Castro Valley, CA has found some common concerns in the church installations he's managed. (Thorburn Associates was doing two churches a month through 2001, until the economic slowdown, Thorburn says.)

"LCDs are generally better for computer displays, while DLP is better for video," Thorburn says, "but that's not usually the issue in churches where it comes down to how much light we can put on the screen- often an issue of budget."

A frequent brightness target, he adds, is 5,000 ANSI lumens. "Usually for $20,000 we can put 5,000 lumens on the screen, and 5,000 lumens across 100 square feet of screen is a very bright image. But you usually can't get 5,000 lumens out of an LCD projector."

Wagner also cites issues of maintenance and long-term cost. "DLP is the more expensive technology up front," he notes. "But LCDs are considered disposable. They wear out. You should plan on throwing the LCD projector out, but if you buy one of the DLP projectors you can do maintenance on them and keep them in spec. Their useful life is potentially very long."

The big image
Projector type is only one issue, of course. Screen size is also important, and often an area of compromise, says Thorburn. "I've yet to do a church where I could properly size the image," he says. As a rule of thumb, Thorburn says, a designer will take the distance from the screen to the farthest viewer and divide it by eight to determine the screen height. If the farthest seat in the sanctuary is 120 ft away, the screen should be 15 ft high. (Width will be determined by the aspect ratio of the content. For standard video or computer graphics at a 4:3 ratio, a screen 15 ft high will be 20 ft wide.)

Screen size, too, is just one variable in a calculation of factors that Steve Somers, Vice President of Engineering for Extron Electronics, Anaheim, CA, calls "a moving target. "The combination of room size and audience size is the first consideration," Somers says, adding that "ambient light is also a huge consideration. If you've got the room physically [behind the screen], rear projection will have the best combination of resolution and light output, since ambient light falling on the screen is passing through rather than being reflected back at the audience."

In addition, Somers says, "audience perception of resolution falls off pretty rapidly as they're moved away from the screen."

Thorburn, too, prefers rear projection for "a better overall experience." In addition to the lack of room behind the screen, there's a physical limit to screen size for rear projection-the maximum size sheet of Plexiglas that can be shipped and installed. Reflective screens for front projection can be made of fabric, rolled up for shipment, even stitched together into larger arrays. "If you need a 30-ft. high image, we need front projection," Thorburn says.

But that, in turn, means longer throw distances, more light loss…and a whole new look at the calculation.

Battling the sun
Churches with very high brightness environments, though, have a new choice these days, LED screens.

Long associated with stadiums and other huge outdoor venues, these flat-panel displays have also been identified with very poor resolution and have never been thought of as a strong video display medium…until now.

"The new LED stuff is nothing short of spectacular," says Wagner. "Now you can put up smaller displays, a 9x12 or 10x14, and have it be stunning in full room light. A 20-foot LED screen can cost more than $1 million, but it will work in places where you'd never see a projector. LED will outperform five top-of-the-line DLPs stacked together."

Sandra Demond, director of marketing for Creative Technology of Los Angeles, cites a recent sale her company made to Harvest Church in greater Los Angeles as a prime example. Harvest Church is moving its LED display around to various outdoor locations. "Projectors can't compete with the sun," Demond says, "but LEDs can."

Lighthouse International is an LED screen manufacturer that's "recently been seeing more requests and sales of LEDs for churches, and for video screens in particular," says Sales and Marketing Coordinator, Jennifer Johnston. In addition to the brightness advantage, Johnston notes, "rear projection takes up quite a bit of space, and front projection requires a clear shot from the projector to the screen." As a self-contained system, the LED panel avoids these difficulties. "The quality of the image is getting better all the time," Johnston says.

Plasma screens an option?
Some churches are buying plasma displays for a variety of applications, including overflow rooms, lobbies, under-balcony displays, and the like. The biggest advantage of plasmas is their flat profile, which enables them to be displayed in very tight spaces.

They also have many drawbacks, including size. The largest plasma screens available are 60 in. wide. And the optimum viewing distance for a plasma screen is two or three times the screen size, so these large plasmas are limited to rooms where viewers will be within 15 ft. And their cost is an impediment, too; prices can top $10,000, and sometimes get above $15,000 per unit.

To solve this complex equation, designers, systems integrators and other experts generally suggest their clients focus on congregation needs and content rather than becoming bogged down in product minutiae. With such a diverse range of choices available, every church should be able to fasten on a solution that's just right for its particular community and mission.