A Look Inside DLP

In Uncategorizedby tfwm

Browsing the Internet the other day, I came across something I wasn’t looking for, which is no surprise. What was a surprise, was finding a software package called “WorshipCenter Pro” that claimed, among its many other alleged benefits, to feature built-in support for the PowerPoint presentation graphics program. Even more surprising was another site I stumbled upon which boasts of projector-ready worship backgrounds, sermon templates and formatted songs. If I needed confirmation that a projector is now a mainstream piece of equipment for the average house of worship, there it was.

In its most recent US Projector Market Analysis Report, TFCinfo Corp, the worldwide leader in audiovisual (A/V) market research and consulting, reported that 58.8% of churches are currently looking to purchase and expand upon their projection systems. And the 17th Annual Contractors Survey, published in Sound & Communications magazine, indicates that the house of worship market is the single largest segment of business for audiovisual installers. As further proof of this growing trend, a ‘virtual’ cottage industry has developed to provide assistance and support on-demand for technology-weary churches and ministries.

Though projectors are commonplace today, it may come as a surprise to many people that projectors first saw the light of day in the late 1980s. For the most part, those projectors were based on LCD (Liquid Crystal Display) technology. But a Texas Instruments (TI) scientist, Dr. Larry Hornbeck, was developing a new imaging technology that, he thought, would be a dramatic improvement on the alternative display technologies.

Dr. Hornbeck’s vision was to create a display technology that would be digital rather than analog, meaning that it would be more accurate at reproducing images repeatedly. It would be reflective rather than transmissive, so it would be more efficient at transmitting an image to the screen. It would use inorganic materials rather than organic materials, making it more durable and reliable. Because it would be fabricated using proven semiconductor technology, it would be incredibly fast. Dr. Hornbeck’s invention became known as the Digital Micromirror Device, or DMD, which became the heart of DLP technology, an imaging technology that has revolutionized the world of projectors since the first prototypes were unveiled in 1994.

The principle of the DMD is very simple. It uses an array of microscopically small, square, hinged mirrors, each of which acts as a light switch. One mirror corresponds to one pixel in the projected image, so an XGA resolution (1,024 x 768 pixels) application will use a DMD that comprises an array of 1,024 x 768 mirrors.

Under opposite corners of each mirror are electrodes that cause the mirror to tilt 12 degrees in either direction. As each mirror has only two states- 12 degrees in one direction or 12 degrees in the other- DLP technology can truly be said to be a digital technology. The electrodes are activated by the graphics or video signal in the underlying memory chip. Tilting the mirror in the ‘on’ direction causes light from a lamp to be reflected out through a lens and onto a screen, where it appears as a white pixel. Tilting the mirror in the ‘off’ direction causes no light to be passed through the lens and on to the screen, resulting in a black pixel in the corresponding position on the screen. Shades of gray are created by varying the proportion of time a mirror is on or off. Each mirror can switch on and off up to 5,000 times/second. The human eye integrates this and does not see the individual switching movements.

In a simple projection system, only a single DMD is used. Color is created by placing a rapidly-rotating color filter wheel between the lamp and the surface of the DMD. Now, instead of white light falling on the surface of the mirrors, red, green and blue light shine sequentially on them. Up to 16 million colors can be created by varying the proportion of time a mirror is reflecting red, green or blue light. For example, to create a purple pixel, the mirror responsible for that pixel would be switched ‘on’ when red light is shining on it and also ‘on’ when blue light is shining on it. The human eye integrates the rapid switching of the red and blue light and sees only a purple pixel.

One of the single most significant advantages of Dr. Hornbeck’s invention is its incredible speed. Because the individual mirrors/pixels can be switched on and off 5,000 times each second, a single ‘panel’ (in this case, an array of mirrors) can switch red and green and blue light. By contrast, other slower technologies require one ‘panel’ each for red, green and blue. The impact of this simple difference is enormous. Using only a single panel means that a much smaller, lighter optical system can be used, which in turn means much smaller, lighter projectors are possible. The world’s smallest/lightest projector weighs less than 2lbs and is based on DLP technology. Similarly, all projectors weighing less than 4lbs on the market today are based on DLP technology. Projectors based on DLP technology also lead the competition in what is known as ‘lumens/lb’. In other words, the amount of brightness delivered per pound of projector weight. That makes them uniquely portable and flexible.

As well as enabling the world’s lightest projectors, DLP also enables the world’s brightest. At 17,500 lumens, these projectors are about ten times as bright as the average portable projector. Projectors featuring DLP technology also feature the highest contrast ratio (routinely above 2,000:1) which contributes enormously to the perceived sharpness of, and detail in an image.

A variant of DLP technology, DLP Cinema technology, is causing a revolution to take place in the movie industry. No longer do movies need to be shipped in huge canisters to each movie theater around the country. Now projectors can show movies that look just the way the director intended them. A movie can be transmitted as a digital file (via DVD, the Internet or satellite) to any cinema around the world in a matter of seconds, potentially saving the movie industry hundreds of millions of dollars each year. Around eighty movie theaters in North America are now equipped with these new projectors.

So what does the future hold? Rather boringly, the answer is “more of the same.” It could be summed up in three simple words: lighter, brighter, cheaper. DLP technology will almost certainly allow the development of the world’s first one-pound projector in the not-too-distant future. Projectors featuring DLP technology will continue to set the standard in lumens/lb. As with projectors based on other technologies, prices of projectors based on DLP technology will continue to fall. The InFocus X1 projector, for example, can already be bought for a remarkable $999. You’ll also see something of a revolution in home entertainment, as home cinema projectors and large screen TVs become available at increasingly affordable price points.

Projectors will unquestionably become brighter and lighter, more fully featured and easier to use. But will they ever include a complete version of the King James Bible? It’s unlikely. For that, you’ll still need “WorshipCenter Pro.”