Four styles of HDTV
Rear-projection TVs: CRT, DLP, LCD, and LCoSThinking of going big? Sure, you could buy a 65-inch plasma, but most people who want to maintain a good credit rating will opt for a rear-projection television (RPTV) instead. These sets start at 42 inches (diagonal), and almost all have a 16:9 aspect ratio and are HDTV-compatible. Their big screens hide two basic varieties of display technology: Old-fashioned CRT tubes, and microdisplays that use DLP, LCD, or LCoS technology. Here's an introduction to the choices.
 The popularity of bulky CRT-based rear-projection sets is fading fast. Low prices will keep CRT-based big screens in the game for another year or two, and videophiles may indeed point out that the best examples of this technology still provide superior image quality in many ways. They still have better black levels than any microdisplay; they generally have deep, well-saturated color; and they can achieve a sharp picture if adjusted properly. Truly good-quality CRT-based big-screens are basically nonexistent now, however, and the product category as a whole is destined to die off sooner rather than later. Microdisplays Smaller box: Microdisplays are lighter, shorter, and thinner than CRT-based rear-projection HDTVs.
 Samsung's pedestal-mounted HL-R5087W DLP TV shows off the possibilities of microdisplay design. A tremendous range of DLP-based sets are available today, and their image quality varies greatly according to price and manufacturer. Entry-level models, among the least-expensive microdisplays you can buy, generally have 720p native resolution (1,280 x 720), although naturally they can also accept and display 1080i HDTV signals. Step-up models have 1080p resolution (1,920 x 1,080), which can deliver sharper images with 1080i HD and computer sources. Both 1080p and some 720p DLP televisions use a technique called wobulation to achieve their stated native resolutions. With wobulation, which Samsung calls SmoothPicture, the DLP chips have half as many physical pixels (a 1080p chip has 960 x 1,080 pixels). A tiny mirror or lens moves rapidly back and forth to alternately create the first and second halves of the image and achieve 1,920 x 1,080 resolution. Wobulation can produce good results, and on some 1080p TVs, it can technically deliver all 1,920 lines of horizontal resolution; on other sets, it makes the image look softer. As usual, performance varies from model to model. One potential problem with DLP sets is known as the rainbow effect. Some people can see brief streaks of color on these TVs, especially in images with black fields and some bright features (such as a spaceship). This is caused by the fact that the single DLP chip uses a color wheel to create red, green, and blue, and hence all colors. The occurrence of these rainbows has been significantly reduced with the advent of newer, faster color wheels, and most people who watch a DLP never see rainbows at all (and the few who do usually see them only occasionally). DLP HDTVs do introduce a bit more low-level video noise, which can look like tiny dancing pixels or motes in shadowy areas, than other microdisplay TVs. Upcoming DLP technologies address a few of these issues. At CES 2006, Samsung announced a DLP set with an LED light source (as opposed to a traditional lamp), which the company says will reduce rainbows and have other benefits. A few other companies will also offer LED DLPs this year. Mitsubishi demonstrateda laser-powered DLP HDTV at its 2006 line show but doesn't expect to ship one until late 2007. Nonwobulated 1080p DLP chips have also been developed for front projectors, and we expect them appear in high-end DLP RPTVs by 2007.
While less popular than DLP models, LCD-based rear-projection sets should continue to do well as long as the Big S stays in the game. Sony has developed a better chip than LCD, however, which it calls SXRD (see below) and puts in its higher-end rear-projection HDTVs. Until LCD makers bring a true 1080p microdisplay to market, the technology will remain the province of entry-level sets. The best DLP and LCoS sets still hold the lead in producing the deepest blacks, but LCD chips have made serious improvements. Translation: Unless you have them side by side, you probably won't be able to tell which of the two delivers the deepest blacks. Prices for similarly sized DLP and LCD TVs will likely remain close as big-brand behemoths face off and try to outdo one another. Another area where DLP and LCoS have an image-quality advantage is something called the screen-door effect. If you sit close to an LCD, you may notice a faint grid of pixels, much like a screen door, overlaid atop the image. You're seeing the space between the pixels, which is more visible on LCD than on the other two microdisplay technologies. It's generally not noticeable even on LCDs unless you sit closer than twice the diagonal measurement of the screen. LCD and LCoS also generally have more white-field uniformity issues than DLP. With expansive flat fields, such as the ice in a hockey rink, some LCD and LCoS sets introduce slight discoloration into some areas of the screen. This effect varies widely from model to model, but DLP sets are generally immune. DLP sets are also generally capable of producing brighter images than LCDs. LCD's big advantage over DLP, and one that it shares with LCoS, is lack of the rainbow effect--a big deal if you see rainbows on DLP sets and a moot point if you don't. Don't put too much stock in the slightly higher native resolution afforded by some LCD chips; in the big scheme of things, 1,386 x 788 doesn't provide much of a sharpness boost over 1,280 x 720. DLP makers have also claimed that the organic compounds in LCD chips degrade over time, while DLP chips do not. Though this is essentially true, it has little impact on real-world product life span because LCD chips still last very long time under normal working conditions. While LCoS and DLP makers tout the "inorganic" nature of their chips, we don't consider that a major reason to choose one technology over another. LCoS
 JVC, with models such as the 1080p HD-61FH96, is one of only two major-name manufacturers of LCoS-based HDTVs. JVC (HD-ILA): JVC has been producing LCoS-based front projectors for years under the D-ILA (Direct-drive Image Light Amplifier) brand, and in 2004, the company proffered a line of rear-projection sets, exemplified by the HD-52Z575 and employing yet another abbreviation: HD-ILA. JVC's 2005 HD-ILA lineup expanded on the previous year's, adding a step-up 1080p series that includes the very solid-performing HD-61FH96--more proof that high-end LCoS sets pose the biggest challenge to DLP. Sony (SXRD): Much like JVC, Sony rebranded its LCoS chip, choosing to call it SXRD (Silicon X-tal Reflective Display or Silicon Crystal Reflective Display). Despite their high prices, Sony's SXRD sets remain extremely popular. So far, the company hasn't officially announced any new 2006 SXRD sets, but it's just a matter of time. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1: Direct-view (tube) TVs
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