How to Buy a Rear-Projection TV
In a TV market where "big-screen" increasingly means "flat-panel," rear projection remains an excellent alternative if you don't require an extremely shallow profile or wall mounting.
As a matter of fact, stand-mounted plasma or LCD TVs often wind up not much slimmer than today's rear-projection models, which typically are just 11 to 18 inches deep. Plus, RPTVs often weigh less at a given screen size (only a few tip the scales at more than 100 pounds). And especially for screens larger than 50 inches, they frequently cost less. Rear-projection TVs come in multiple flavors, however; here's what you need to know to sort through the alternatives.
The Big Picture
Big doesn't necessarily mean bulky anymore. Today's microdisplay technologies--DLP, LCoS, and LCD--deliver superb high-definition pictures from cabinets much smaller and lighter than those of the CRT rear-projection TVs of yesteryear. more
The Specs Explained
We give you the lowdown on all those strange names and numbers. more
Rear-Projection TV Shopping Tips
Before you pull out your wallet, understand how to match size and technology to your needs and budget. more
The Big Picture
Many TVs with screens bigger than about 42 inches diagonal are rear-projection designs. They project a video image inside a box and direct it by means of lenses and mirrors onto the inner surface of a translucent screen. Originally, all used cathode-ray tubes, or CRTs, to create the image. Although this technique works well, the chassis is heavy and requires a relatively large, usually floor-standing cabinet.
As screens have grown and TV has begun migrating to the new, wider 16:9 aspect ratio (ratio of width to height), CRT-based designs have been displaced by new technologies that offer similar or better performance in lighter, more compact enclosures.
Regardless of technology, today's rear-projection TVs are all high-definition displays, able to take full advantage of digital HDTV broadcasts and discs. (HDTV provides wide-screen pictures with much greater clarity and detail than conventional television.) Built-in HD tuners are now standard, and all sets include tuners for regular analog broadcast and cable TV as well; the ability to receive unencrypted digital cable without a set-top box has also become a near-universal feature.
Digital light processing projectors are based on Texas Instruments' Digital Micromirror Device, which is actually a chip manufactured using semiconductor-fabrication techniques. Its method of operation sounds preposterous--thousands of microscopic mirrors flipping back and forth under microprocessor control--but is spectacularly effective. As with LCD sets, the light source is normally a user-replaceable, high-intensity lamp that will last for years in normal use, although some models now use LED light engines instead for quicker turn-on, much longer life, and better color reproduction. In fact, DLP and LCD rear-projection TVs are very similar in nearly every aspect of their physical construction, sharing the light weight and shallow cabinet depth that are such a big part of their appeal. Screens range from 46 inches to 73 inches diagonal; prices run from about $1200 to $5900, though relatively few have list prices higher than about $3500.
Also like LCD sets, DLP projectors are not subject to burn-in or declining brightness with age. Their handling of blacks and dark grays is superior, however--close to the performance of CRTs. A very small number of people occasionally notice a fleeting separation of colors ("rainbows") on moving objects when they move their heads or eyes quickly, but for most this is not an issue. (Projectors that use LED light sources instead of a white lamp with a color wheel to generate colors from a single DMD chip are immune to this effect.) All current DLP rear-projection TVs are wide-screen displays with a resolution of 1280 by 720 (720p) or 1920 by 1080 (1080p), and almost all are tabletop designs.
The oldest alternative imaging device in RPTVs is the liquid-crystal display, or LCD. Several manufacturers now use small LCD panels and high-intensity lamps to produce lightweight, high-performance rear-projection TVs. Even a 61-inch set will be less than 20 inches deep and weigh less than 100 pounds. And LCD sets can go on a shelf; floor stands are optional. Screens range from 37 inches to 61 inches diagonal, and prices range from about $1000 to $2400.
LCDs are not susceptible to burn-in and do not gradually lose brightness over time as CRTs do. On the other hand, they have a harder time producing deep blacks and gradations of dark gray, which can make LCD sets look a little washed out compared with CRTs. Manufacturers have worked hard to mitigate this weakness, however, and the best LCD projectors tend not to be as obviously challenged in this respect as they once were. All LCD rear-projection TVs are wide-screen displays, usually with a resolution of either 1280 by 720 (720p) or 1920 by 1080 (1080p).
Liquid crystal on silicon, or LCoS (also known as D-ILA, for direct-drive image light amplifier, or SXRD, for silicon x-tal reflective display), is a liquid-crystal display technology. But unlike conventional transmissive LCD panels, LCoS chips use a reflective silicon substrate, so that light bounces off them rather than passing through. Like DLP and LCD, LCoS allows production of shallow, lightweight, high-performance displays. A big appeal of this technology has always been the tight pixel packing it allows, which helps keep the picture smooth on very big screens. Screens range from 50 inches to 70 inches diagonal; prices range from about $2300 to $6000.
The strengths of current LCoS sets are similar to those of DLP models, though the best models may provide even better blacks and dark grays. In addition, all current implementations are three-chip designs (one for each primary color), which eliminates the possibility of the "rainbow" effect that some people observe with conventional DLP models. All current LCoS sets have 1920 by 1080 (1080p) resolution and are built for table or stand mounting.
The Specs Explained
Gone are the days when you figured out how big a screen you wanted, looked at some sets, and bought the one with the best picture that fit your budget. An options explosion has littered the shopping landscape with numbers, features, and terminology that even experts sometimes have trouble tracking. So we've tried to boil it down to the basics that can actually do you some good. (In audio and video, never forget that just because something has a number to describe it doesn't mean it really matters!)
We've divided the specs into three categories: important, somewhat important, and minor.
Important: Aspect Ratio
The aspect ratio describes the relationship of screen width to screen height. Conventional sets have a 4:3 aspect ratio, whereas wide-screen models are 16:9. Wide screen is the future. HDTV is a wide-screen format, for one thing. For another, DVDs usually look better on wide-screen displays because nearly every movie made in the last 50 years was filmed in an aspect ratio of either 1.85:1 (very close to 16:9, which is 1.78:1) or 2.35:1 (even wider than 16:9).
Somewhat Important: Resolution
For CRT displays, resolution typically is specified according to standard broadcast TV formats, such as 480i, 720p, 1080i, and so forth. The 720p and 1080i formats are high definition. Non-CRT displays, such as LCDs and DLPs, are fixed-pixel arrays, which means they have rows and columns of individual picture elements that turn on and off to produce the necessary patterns of light. Resolution is usually specified as the number of pixel columns by the number of pixel rows--640 by 480, for example, or 1280 by 720.
Perceived picture detail depends primarily on display resolution. Generally speaking, a display is considered high definition if it is wide screen and has a total pixel count approaching 1 million. So 1920 by 1080 (1080i or 1080p), 1280 by 720 (720p), and 1366 by 768 are all examples of high-definition display resolutions. Small differences are usually not very consequential; you would probably not see much, if any, difference between the three examples just cited unless you were sitting close to a large screen (say, less than 10 feet from a 50-inch display)--which is why we consider this spec only somewhat important. Since all current rear-projection TV models are high-definition displays, resolution is not the biggest point of differentiation among them.
Important: Video Inputs
The number and type of video inputs determine which sources you can use with the display.
Composite video: This input type has the lowest quality but the broadest compatibility. Any device that has video outputs will include composite video among them. Connection is made with a single 75-ohm coaxial cable between RCA jacks.
S-Video: S-Video offers better quality than composite video, and most video sources except standard VCRs now have S-Video outputs. Connection is made with a special cable and multipin sockets.
Component video: This high-quality option is the minimum standard for connecting HDTV cable and satellite boxes and progressive-scan DVD players. It requires three 75-ohm coaxial cables of the same type used for composite video.
VGA: Video graphics array is a high-quality analog RGB connection used for computer connections and sometimes in place of RGB+H/V.
DVI: This is one of the highest-quality types of inputs. Digital visual interface is a digital video connection that can link to devices with HDMI outputs (see below) by means of an adapter. It may also be used for computer connections. Requires a special cable and multipin sockets. Some displays with a DVI input may work only with computers, so watch out for that if you plan to connect an HDTV source, such as an HD digital cable box or an HD DVD or Blu-ray Disc player. Another thing you need for guaranteed HDTV compatibility is compliance with the HDCP (High-bandwidth Digital Content Protection) system.
HDMI: Also of the highest quality, High-Definition Multimedia Interface is basically DVI plus a digital audio and control link, and it normally incorporates HDCP; it can be mated to DVI with adapter cables. This connection is provided on almost all current HD satellite receivers, HD cable boxes, and upconverting DVD players (those that provide 720p, 1080i, or 1080p output from regular DVDs). It is also the standard video connector for HD DVD and Blu-ray Disc players. The exact version of the HDMI input (e.g., 1.1 or 1.3) is of little consequence on TV sets. If you have or plan on getting an HD DVD or Blu-ray Disc player, it is desirable, though not essential, that the TV's HDMI inputs be capable of accepting 1080p signals (most now are).
Important: Viewing Angle
Because of the nature of their screens, rear-projection TV images tend to lose brightness as you move away from directly in front of them, especially on CRT-based sets. The effect is usually more pronounced vertically than horizontally, but since people tend to watch from the same height all the time, the vertical fade is less important. How much the horizontal viewing angle matters depends on how your seating area is set up, but the closer a set gets to a 180-degree acceptable viewing angle, the better. And though a viewing-angle spec can be a handy rough guide, there is no substitute for checking this out with your own eyes.
Somewhat Important: Built-In Tuners
You can expect any rear-projection television to include tuners for conventional analog broadcast and cable TV reception and for broadcast HDTV. And it almost always will have a built-in tuner for digital cable TV as well. Although a standard for handling scrambled premium channels (for example, HBO) exists in such tuners, few sets support it, so be sure you know exactly what you are getting. If you want that capability, make sure the set you buy has a CableCard slot and that your cable provider can provide you with the necessary electronic ID card. Cable pay-per-view services and satellite TV currently require external set-top boxes.
Minor: Comb Filter Type
Comb filters are necessary in analog TV to separate color and luminance information without losing too much detail, but that's not an issue in HDTV. The only time the comb filter comes into play is for analog TV reception or any signal coming in through a composite video connection. For all other connections, it's out of the loop. Plus, the comb filters in today's rear-projection TVs are routinely very good.
Rear-Projection TV Shopping Tips
Ready to buy? Here are key points to consider before you make the big commitment.
Make some measurements: Some rear-projection TVs have very large cabinets. It's important not only that whatever you buy fits where it needs to go in the room but also that it can be maneuvered through halls, doorways, and stairways to its final destination.
Think HDMI: If at all possible, you should get a set with at least one, preferably two or three, HDMI (High-Definition Multimedia Interface) inputs. This will ensure full compatibility and maximum performance with HDTV sources such as HD satellite receivers, HD digital cable boxes, and HD DVD and Blu-ray Disc players.
Compare displays using a variety of material: Just about any current rear-projection set will handle HDTV and DVD signals well, but mediocre cable and satellite signals will give some of them fits. Don't make a buying decision based solely on pictures generated from pristine sources.
Look for good blacks: When you head to the store, bring a DVD of a movie containing some dimly lit night scenes. Use it to check for good black reproduction and ability to render detail in near-darkness.
Take a walk: Around the TV, that is. How does the picture hold up as you move away from the center toward the sides? Also, when comparing the picture on two different sets, make sure you are looking at them from the same vertical angle. If one screen is at a greater distance above or below your eye, it will almost always look darker and duller.
Get to know the remote: A good remote can be your best friend, a bad remote your worst enemy. (Well, okay, we're exaggerating a little, but you get the idea.) Does it have backlighting or glow-in-the-dark buttons to help you see what you're doing when the lights are turned down? How easy is it to find commonly used buttons by feel?
Check the video settings: Now that you've got the remote, pull up the video-adjustment menu and look at the settings. If you thought the picture looked a little (or a lot) off on first viewing, try choosing the median settings for contrast, brightness, color, tint, and sharpness. Those probably won't be optimum, but chances are they're closer than what you found originally. A good display can easily look worse than a lesser one if it's poorly adjusted. Repeat your tests using a variety of sources, including a dimly lit movie, if necessary.