How Do DLP TV's Work?

A Buyer's Guide

DLP (Digital Light Processing) technology is a revolutionary display solution that uses an optical semiconductor to manipulate light digitally. It's a proven and dependable technology preferred by leading electronics companies worldwide. At the heart of every DLP TV projection system is an optical semiconductor known as the Digital Micromirror Device, or DMD chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in 1987. The DMD chip is the world's most sophisticated light switch. It contains a rectangular array of up to 1.3 million hinge-mounted microscopic mirrors; each of these micromirrors measures less than one-fifth the width of a human hair. When a DMD chip is coordinated with a digital video or graphic signal, a light source, and a projection lens, its mirrors can reflect an all-digital image onto a screen or other surface. The DMD and the electronics that surround it are called Digital Light Processing technology (DLP). A DMD panel's micromirrors are mounted on tiny hinges that enable them to tilt either toward the light source in a DLP projection system (ON) or away from it (OFF)-creating a light or dark pixel on the projection surface. The image code entering the semiconductor directs each mirror to switch on and off up to several thousand times per second. When a mirror is switched on more frequently than off, it reflects a light gray pixel; a mirror that's switched off more frequently reflects a darker gray pixel. In this way, the mirrors in a DLP projection system can reflect pixels in up to 1,024 shades of gray to convert the video or graphic signal entering the DMD into a highly detailed grayscale image. The white light generated by the lamp in a DLP projection system passes through a color wheel as it travels to the surface of the DMD panel. The color wheel filters the light into red, green, and blue, from which a single-chip DLP projection system can create at least 16.7 million colors. The on and off states of each micromirror are coordinated with these three basic building blocks of color. For example, a mirror responsible for projecting a purple pixel will only reflect red and blue light to the projection surface; our eyes then blend these rapidly alternating flashes to see the intended hue in a projected image. The switch to DTV broadcasting In 1996, the Federal Communications Commission (FCC) enacted legislation convincing the nation's 1600+ television stations to change the way they broadcast their programming and to start transmitting it digitally. Digital Television (DTV) began rising in America ever since then. For now, the FCC allows the media to offer digital broadcasts in parallel with their existing analog ones, giving consumers the opportunity to watch regular TV while they make the switch to DTV. Once the transition to digital TV is complete it is estimated that by the year 2006 85% of US households will get digital feeds, meaning that DTV will be the new standard in broadcasting replacing analog broadcasting. Sure, you'll still be able to watch your favorite shows in analog like always, but you'll need to "update" your existing TV with a device that converts digital signals into analog ones. All of which begs the question: Why not just go with the digital flow? How does DLP technology compare? DLP VS LCD DLP technology is superior to LCD projection in numerous ways. Digital Light Processing technology ensures that every pixel on your projected image gets exactly the same amount of light; there is no fading around the edges of the screen, and colors look sharp. Also, DLP consists of one single chip, instead of three bulky LCD panels, resulting in smaller lighter
projectors without any loss of image quality. Reduced pixellation is another benefit of DLP. LCD Televisions were always known for their visible pixel structure, often referred to as the screen door effect because it appears as though the picture is being viewed through a screen door. DLP will always give you the better visual image and it can produce higher contrast video with deeper black levels than you normally get on an LCD projector. DLP Televisions have Higher Contrast. The simple optical system reduces the unwanted effect of "stray" light, allowing for better contrast ratios, which means sharper, more detailed images. There is one single issue that people point to as a weakness in DLP, it is that the use of a spinning color wheel to modulate the image has the potential to produce a unique visible artifact on the screen that folks refer to as the "rainbow effect," which is simply colors separating out in distinct red, green, and blue. Basically, at any given instant in time, the image on the screen is either red, or green, or blue, and the technology relies upon your eyes not being able to detect the rapid changes from one to the other. Unfortunately some people can. DLP VS Plasma When you compare DLP technology to Plasma technology an important thing to look at is the contrast. Plasma televisions have better black levels than DLP televisions do and their slim build gives them a thinner look than DLP televisions have. DLP TVs have a huge advantage when it comes to price and value. DLP technology is much less expensive to reproduce than Plasma technology is and a DLP television will last you a longer to. The expected life span of a DLP television is close to 100,000 hours compared to approximately 30,000 hours with Plasma televisions. Plasma Televisions have the advantage when it comes to viewing angles typical Plasma has a viewing angle of about 160° compared to DLP, which only have a viewing angle of about 100°. What to look for when buying your DLP Television? Image Quality Buying a DLP TV is your first step to getting the clearest, most cinematic image your money can buy. The major factors to consider when choosing the right DLP projector are resolution and brightness uniformity. Resolution is the number of pixels from side to side and top to bottom of your image. The clearest answer for choosing the right resolution is to buy the best you can afford. Currently SVGA and XGA are the most common resolutions. An XGA projector has about twice the number of pixels of an SVGA projector, but it also costs a bit more. Brightness uniformity is also important. Uniformity is the percentage of brightness carried throughout the image. Some projectors have difficulty carrying the peak lumens all the way to the corners of the screen. A higher uniformity percentage indicates that the projector carries out an equal amount of brightness from the center to the corners of the image. That means fewer hot spots (bright areas) and an even distribution of light throughout the image. Lamp Life and Projectors DLP projectors typically have a lamp life of between 1000-2000 hours. This spec is actually the lamp's 'half-life.' The half-life is the point where the lamp is half as bright as it was new. The lamp will still work at its half-life, but it will continue to gradually lose brightness. Longer lamp life means less expense in maintaining your projector. If you are planning to use your DLP projector to replace your current television, lamp replacement cost should be factored into your purchase. Replacement lamps run approximately $299-$450. If your projector will be used primarily for watching movies and special events, lamp life will not be quite as important. But you may still want to factor the cost of a replacement lamp into your purchase. The average projector used in this manner runs approximately 8 hours a week. Lamps typically last between 1000-2000 hours. Replacement lamps cost between $299-$450. Aspect Ratio Is the width of your image divided by the height. There are several different aspect
ratios used in film and television today. Your standard NTSC broadcast is in the 4:3 aspect ratios. DLP video projectors come in two different ‘native’ aspect ratios - 4:3 and 16:9. Native resolution means that the chip inside the DLP projector, which is like a miniature version of the image, is shaped in the specified 4:3 or 16:9 dimension. Most projectors can switch between 4:3 and 16:9 ratios, but you will see black bars either on the sides or top and bottom of your image. If you will be using your DLP™ projector for standard TV, HDTV, and DVDs, make sure your DLP projector can switch between modes. Connectivity and Compatibility These are both factors for getting the clearest images. Some projectors are specifically designed for home theater use, so they have multiple inputs for video, special video chips and other features. Other projectors may not have been created solely for home theater use, but they still produce great video. Warranty Most Flat Screen TVs come with a 1 Year limited warranty from the manufacturer, some times covering Parts & Labor and sometime just the parts. Regardless, being that you'll most likely keep your new expensive TV a lot longer than 1-2 years (usually at least 6 years) you should consider investing in an extended service contract sometime referred to as an extended warranty or ESP Extended Service Plan. ESP - Extended Service Plan (extended warranty) If you've just purchased a new TV the smartest move you can make as a consumer is to protect your investment by purchasing an ESP (Extended Service Plan). Plasma, LCD and DLP TVs all use Digital technology, which can be somewhat fragile. Many factors can have a negative effect on Digital TV displays especially after the manufacturers warrant runs out, usually about a year. The peace of mind you buy with an extended warranty is well worth it, as you'll never have to worry about expensive repairs. Additionally, in the event of a malfunction, the cost of packing up a big screen TV and shipping it across the country to the manufacturers repair center can cost more than the price of an extended service warranty.