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Direct-view CRT (cathode-ray tube) Tube TVs have been around for decades, and though they're slowly going away as big-name brands focus on new technologies, the best of the breed can still deliver superb pictures. And they're affordable. (some 34 inch wide screen sets sell for less that $1,000) But the screens on direct-view models are relatively small, and their cabinets are bulky and very heavy. (They're called "direct-view" because you look right at the tube, unlike rear-projection CRT TVs, in which the beams from separate red, green, and blue tubes combine to form a full-color image on the screen.) Currently, the largest CRT models with 4:3 aspect-ratio screens are 36 inches, and the largest widescreen model is 38 inches. If you're considering a direct-view set, look for one with a flat tube. Unlike traditional curved tubes, flat-screen tubes perform well in all lighting conditions - although glare from the glass screen can still be a problem. Rear Projection (RPTV) Many people associate "rear projection" with fuzzy, out-of-focus images unwatchable from anywhere other than right in front of the screen. But today's rear-projection TVs (RPTVs) bear little resemblance to their poor-performing ancestors. New technologies like DLP (Digital Light Processing), LCD (liquid-crystal display), and LCoS (liquid crystal on silicon, a.k.a. Direct-drive Light Amplifier, or D-ILA, and Silicon X-tal Reflective Display, or SXRD) deliver stunningly bright, detailed images and permit far wider viewing angles than traditional CRT-based RPTVs. But these technologies carry a premium price - around $2,000 for HDTVs in the 50-inch range to around $3,500 for some 60-inch sets. CRT models, on the other hand, will give you the biggest screens for the lowest prices, with many 50-inch widescreen sets selling for less than $2,000. Sizewise, RPTVs begin where direct-view tubes leave off, with screens ranging from 40 to 82 inches. These big screens often mean big - and heavy - cabinets, but the newer technologies have allowed for much slimmer designs, many less than 17 inches deep for a 50-inch screen. Flat Panels The sexiest designs by far are flat, hang-on-the-wall plasma and LCD sets. Measuring less than 4 inches thick, these high-tech marvels provide amazingly bright pictures while taking up virtually no space. LCD owns the market at sizes less than 40 inches, while plasma reigns from 42 inches up. Prices increase dramatically with size. LCD sets range from 15 inch models selling for $400 up to 45 inches that sell for just under $5000. Plasma starts about where LCD maxes out, from 42-inch models priced as low as $1500 up to a 63-inch HDTV with a list price of $13000. Both plasma and LCD sets offer bright, detailed images, are very resistant to glare, and have phenomenal off-angle viewing - up to 160 degrees. While current plasma sets top out at 65 inches, LG and Samsung have shown working prototypes with screens bigger than 75 inches. In addition to going larger, a number of manufactures have been developing new flat panel TV technologies to provide us with even better pictures then are currently available with plasma and lcd, without their drawbacks. The two main technologies are Organic Light Emitting Diode (OLED), and Surface Conduction Electron Emitter Display (SED). These technologies will allow for brighter more brilliant images, greater longevity, and the absence of premature phosphor aging (burn-in). Look for these new TV's to be available near the end of 2006 for your viewing pleasure Front Projection For the ultimate home theater experience, you need a front projector. Similar to movie-theater projectors because they project the image onto a screen on the other side of the room, these models can create detailed images as big as the side of your house - though 80 to 120 inches is typical. And a front-projection system can disappear when not in use. With a motorized screen and recessed projector mount, even the largest screen and projector can completely vanish. Three-tube CRT front projectors, which once ruled this market, are rapidly being replaced by smaller, cheaper, more installation-friendly technologies like LCD ($1,000 and up for a high-def projector), DLP ($3,000 and up), and LCoS ($9,000 and up). The new technologies use a single lens instead of a CRT projector's three, making them easier to install and maintain. Entry-level models start at $800 but have only EDTV resolution. And JVC's xHD-iLA (as well as Sony's SXRD) projectors provide ultra-high 1080p resolution. But for money-no-object, reference-quality projectors, models using 9-inch CRTs are still the champs, fetching prices over $25,000. Display Technologies CRT Cathode-ray tube technology was used in the very first TVs, and after all these years, it's still the most common and inexpensive way to get a video image in your living room. Direct-view CRTs are the familiar glass-fronted TV sets, which have evolved to include flat-glass and widescreen varieties. Rear- and front-projection CRTs use three tubes side by side (one each for red, green, and blue) to create an image that's then sprayed onto a large screen. How It Works - Direct-view tubes contain a "gun" consisting of a cathode that emits three distinct invisible electron beams and anodes that accelerate them. The beams are aimed at red, green, and blue phosphors set into the screen, which glow to produce the picture. (A metal grid on the tube's inside face, called a shadow mask, helps keep the beams on target.) Combining the three primary colors in varying proportions produces the full color range. In the three-tube designs used in big-screen projection TVs, each tube fires at its own small screen with a single color of phosphors. Lenses and mirrors focus the colored images onto the viewing screen. The tubes must be perfectly aligned ("converged") or else distortions such as red or blue fringes around objects will appear. Pros Cons Where It's At - Having graced American living rooms for the past half-century, direct-view sets are fading fast in popularity, especially in the high-end market. Big-screen projection CRTs are being overtaken by lighter, shallower TVs based on other technologies. Plasma Just 3 to 6 inches thick, plasma TVs can be set up next to or mounted on a wall, preserving precious room space. Screen sizes range from 32 inches diagonal to a cinematic 63 inches, and at least one 71-inch model is in the wings. How It Works - Each pixel in a plasma display consists of three gas-filled sub-pixels (cells) coated with red, green, or blue phosphors. Electrodes above and below the cells (the top electrode layer is transparent) jolt them with varying amounts of voltage. This excites the gas in the cells to a plasma state, stimulating the phosphors to produce colored light. Pros Cons Where It's At - Just about every TV maker sells a plasma model. But these slim, sexy sets are still expensive, with $2,000 42-inch enhanced-definition TV (EDTV) model representing the low end of the price scale. Expect to pay $3,700 to $9,000 for a 42-inch HDTV model and $4,800 to $15,000 or more for a high-def model with a 50-inch or larger screen. Don't expect prices to fall to CRT levels for a few more years. DLP Rear-projection TVs can be slimmed down to less than 2 feet deep when chips are used in place of CRTs. One fixed-pixel technology, Texas Instruments' Digital Light Processing (DLP), offers a high-quality, less-expensive alternative to CRT for front projectors. But manufacturers are also starting to roll out more affordable DLP-based widescreen RPTVs. How It Works - High-def DLP TVs use a 16:9 chip, called a Digital Micromirror Device (DMD), packed with nearly a million individually hinged and controlled "micromirrors" that pivot to reflect light from a lamp through a lens onto a screen. DLP sets fall mainly into two camps. Single-chip RPTVs and front projectors filter white light from the lamp through a rapidly spinning color wheel to produce color, while the more expensive ($23,000 and up) three-chip front projectors dedicate one chip each to red, green, and blue. Pros Cons Where It's At - Many manufacturers offer DLP RPTVs, with prices starting at about $2,500. But don't rule out DLP front projectors. Basic models start at around $3,000, while HDTV-ready models range from $4,500 to $15,000. Prices of DLP sets drop every year, and the trend shows no signs of slowing down. LCD The granddaddy of fixed-pixel technologies, LCDs (liquid-crystal displays) first appeared in pocket calculators in the early 1970s. The technology is amazingly versatile, able to power front projectors, rear-projection TVs, and flat-panel displays. But LCDs are only now making headway in home theaters. How It Works - A matrix of thin-film transistors (TFTs) supplies voltage to liquid crystal-filled cells sandwiched between two sheets of glass. As with plasma panels, a trio of red, green, and blue cells make up one pixel. When hit with an electrical charge, the crystals "untwist," allowing light generated by a lamp behind the screen (for flat-panel TVs) or a lamp shining through a small LCD chip (for projection TVs) to filter through. The higher the voltage, the more a cell "opens up." Pros Cons Where It's At - High prices have slowed widespread adoption of LCD TVs, but 43-inch rear-projection models are now available for as little as $2,300. As with DLP, the LCD front projectors offer the greatest variety - and the best deals. Coming Soon SED and OLED Flat Panel Technologies LCoS The least-familiar player at the fixed-pixel poker table, LCoS (liquid crystal on silicon) owes most of its technological heritage to LCD. But it can outperform LCD because it uses smaller pixels that provide higher resolution and almost eliminate the screen-door effect. LCoS has great potential for home theater, but it's only available in a few products. (JVC calls its version of LCoS "D-ILA," for Direct-drive Image Light Amplifier, while Sony uses "SXRD," for Silicon X-tal Reflective Display.) How It Works - LCoS borrows from both LCD and DLP technology. As with LCD, each pixel in an LCoS display has liquid crystals that untwist to transmit light, and - as the name indicates - these crystals are applied to a silicon chip instead of sandwiched between glass. As in DLP, light is reflected off the chip toward a screen. LCoS front projectors and RPTVs can be designed with either a single chip, using a color wheel or prisms to separate the light, or three chips, one for each primary color. Pros oLCoS rear-projection TVs clearly demonstrate the two major advantages this technology has over both DLP and LCD: resolution and pixel spacing. The pixel count of most current DLP and LCD displays max out at 1,280 x 720 and 1,366 x 768, respectively. But each of the three LCoS chips in most current sets is packed with 1,920 x 1,080 pixels - enough to display all the detail in any high-definition TV broadcast. And because the pixels are spaced closer than those of the other projection technologies, the picture is smoother on extremely large screens. Cons Where It's At - LCoS has had a somewhat tortured history, with most companies who have adopted it bailing out soon thereafter (apparently because the chips are very hard to manufacture in quantity). Still, the technology's resolution capability makes it a real contender among fixed-pixel displays, especially for exceptionally large screens. JVC, which has championed LCoS for years with its high-end D-ILA front projectors, now has some RPTV models, and Sony recently made what appears to be a substantial commitment with its SXRD projectors. |
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