FROM THE ARCHIVES: March 5, 2002


The Flat Look

You've decided to buy an LCD screen. Now comes the hard part: How do you choose?


(See Corrections & Amplifications item below.)

Flat-panel computer displays seem to be popping up everywhere. Prized as space savers by professionals such as Wall Street traders and physicians, the screens' falling prices and improved quality are making them popular additions to home computers as well.

This past Christmas, sales of flat-panel screens for home use skyrocketed thanks to prices that fell along with PC demand. Well-equipped, 15-inch screens are selling for as little as $300 in retail stores, and even some large, 18-inch sizes are priced under $900.

But choosing the right screen can be tricky. Flat panels, also called LCDs for "liquid crystal display," use a light and filters that open and close like camera shutters to illuminate an image, unlike traditional displays that use a stream of electrons. The technology allows for thin, compact screens -- and presents a unique set of considerations. Choose too weak a light source, for instance, and the contrast will be poor. Go for a super-high resolution, and older software won't show as well.

'Multimedia Appliance'

Patrick Bevill, a 38-year-old Los Angeles computer enthusiast, recently went shopping for the ultimate home computer. He picked a large, 17.4-inch display that would allow him to watch television, play the latest computer games and view crisp Web-page images. "The PC is turning into a multimedia appliance, and I wanted an LCD that accommodated that," says Mr. Bevill, who plunked down $900 for a model with a transparent case, ultrafast updates, a digital connection and external speakers.

While not everyone has the same needs, the checklist he used could be a good starting point for any LCD purchase. After deciding on screen size and price range, Mr. Bevill says the key choices in picking a flat-panel display are contrast ratio, resolution and brightness. The three should be considered together because of their impact on how well an image is displayed.

Contrast ratio calculates the difference between the white and black displayed on your screen. This is one choice that's relatively easy: The higher the contrast ratio, the better the image. Contrast ratios in the range of 350:1 to 400:1 will deliver richer colors compared with a weak 200:1 ratio.

Bright Idea

Brightness is another key consideration. Light intensity is measured as candelas per square meter, also known as "nits." A low rating of 100 nits would deliver a washed-out look, though if you've been satisfied with a laptop computer, consider that the best-selling laptops from Dell Computer Corp. and Compaq Computer Corp. have screens rated at 130 nits.

A more typical brightness rating on an LCD for home use would be 200 to 250 nits, suitable for use in a small, contained setting such as a den or study. Brighter screens, of up to 400 nits, will deliver images that are more easily viewed from the side or in a sun room.

Resolution is a measure of the density and detail of an image. On a traditional cathode ray tube (CRT) screen, it's expressed as the number of lines in the display, horizontally and vertically. And while LCDs don't actually have lines, the resolution is expressed the same way. The minimum resolution to look for is 1,024 by 768, the format for most 15-inch LCDs and the preferred design spec for most Web pages. This is also the spec used by software designed for so-called XGA video cards, the most widely used among home PCs.

If you plan to use the LCD with PhotoShop or other desktop-publishing programs, you should consider screens with photo-sharp 1,600-by-1,200 resolution. These are found primarily on larger and more costly 17-inch and 18-inch LCDs.

Another factor related to resolution is "pixel pitch," which is the size of the dots that make up the images. Smaller is better, and on most LCDs, it's a respectable 0.29 millimeters or less -- comparable to a good-quality CRT.

A word of caution: LCDs differ from traditional CRT displays in that they don't handle lower resolutions well. Most CRTs can easily adapt to show at full-screen size everything from older software with 640-by-480 resolution, all the way up to 1,600 by 1,200. But a flat panel won't automatically resize when confronted with older programs. Run an application using 640-by-480 resolution on a 15-inch LCD, and you'll wind up with a shrunken image surrounded by a black border, leaving the bulk of that big screen you bought dark and unused.

You can manually alter the resolution settings on the display, but you'll have to go in and change it back again to view higher-quality images.

One way around this problem: Microsoft Corp.'s new Windows XP has a feature called Liquid View that inflates the size of icons and text when running older software on 15-inch and larger screens. It's a particularly useful feature for running older computer programs, says Chris Connery, a marketing manager at NEC-Mitsubishi Electronics Display of America Inc., Itasca, Ill.

Exorcise the Ghosts

Another factor to keep in mind when purchasing an LCD is screen response time. This is one place where LCDs deliver inferior performance compared with CRTs, especially for video and games.

The response time is a measure of how quickly light rises and falls within each screen dot. Slower models, such as those rated more than 50 milliseconds, can adequately run simple applications like tax-preparation software and allow you to surf the Internet. But such response times can lead to ghost images and blurred video, animation and even scrolling text. Many game players who replace a CRT with a flat panel will feel the difference when running fast-paced applications.


Key points to remember when picking a flat-panel display

Contrast Ratio: The higher the contrast, the richer the colors. Look for screens with at least a 350:1 ratio.
If the computer is used in a sunny room, consider 400:1 or higher.

Resolution LCDs: unlike bulky monitors, donÕt adapt to different resolutions well. A 15-inch screen has 1024 by 768 resolution, which is suited to Web-page viewing. Sharper 1280 by 1024 screens are available on 17-inch and 18-inch LCDs.

Tilt/Swivel: If youÕve got kids, make sure you
can secure the base to a desk or countertop. LCDs
are fragile and prone to topple if moved frequently.

Brightness: The brighter the better. Most home-PC screens carry light intensity ratings between 200 nits and 400 nits. The best choice is 250 nits or higher.

Response Time: Games such as Quake III and DVD videos require 25 to 30 millisecond response time. Home productivity programs and Web surfing can get along with 50-80 millisecond response times.

For streaming video and the fast-paced action of racing and shooting games such as Quake III, consider displays with response times on the order of 25 to 30 milliseconds, which can be found on the higher-end screens. CRTs are still nearly twice as fast as that. But at 25 milliseconds, an LCD can handle 40 frames a second of video, good enough for playing advanced games and watching streaming video and DVDs without ghosting.

One of the trade-offs related to response time will be the viewing angle -- meaning how far to the side you can be, for instance while answering the phone, and still see a clear image on the screen. A wide horizontal viewing angle of about 160 degrees allows a clear side view. But "if you have a wide viewing angle, you may give up response time," says NEC-Mitsubishi's Mr. Connery. And on the flip side, a faster response time can mean a narrower viewing angle. At a span of less than 100 degrees, the image becomes distorted and loses its color when viewed from the side.

Knowing what specifications to look for in an LCD is one thing, but finding the information is quite another. "You really have to do your homework," advises Mr. Bevill, the Los Angeles computer maven.

The Web sites of the three largest home-PC makers, Hewlett-Packard Co., Compaq Computer and Dell Computer, list basic screen size and resolution information on LCDs sold with their computers. But for more detailed specifications, you have to hunt around the sites for pages devoted to monitors. Count on calling manufacturers' technical-support lines to get the real low-down.

Don't count on getting the information you need at the store. A recent trek through retail outlets Fry's, CompUSA and Best Buy found little detail on most sales material. And because LCDs only recently have hit retail shelves, few salespeople are versed in the nitty-gritty details. One incorrectly cited a frequency rating when asked for the screen response time.

Most sales pitches emphasized LCDs' lower power demands and lack of screen flicker that can cause eyestrain. Both are valid points but unlikely to prove significant to the average home-PC customer who uses the PC just occasionally. LCDs use less than half the electric power of a CRT, a consideration if you run the computer all day.

As for what this will do to your pocketbook, expect to pay about twice the cost of similar-sized CRTs, which also have come down sharply in price along with LCDs. Stephen Baker, retail analyst at NPD Intelect, a Port Washington, N.Y., market-research firm, says the average price last Christmas for a 17-inch CRT (with a 16-inch viewable screen) was about $230. A 15-inch LCD averaged about $440, he says, compared with $851 a year earlier.

Retail sales of LCDs rose nearly 700% in the fourth quarter last year compared with a year earlier, as prices plummeted, according to NPD. "Price," says Mr. Baker, "is what's moving the market."

One feature that can drive up the cost is a digital visual interface. Most LCDs -- and for that matter CRTs -- sold for home use are analog, meaning the signal coming from the computer, which is in digital format, is converted before being displayed. Digital screens that don't require the conversion have sharper images and cost anywhere from 25% to 40% more. But models with DVI may not work with the lower-quality graphics cards found in many home PCs, and for that reason aren't really practical for home use.

Handle With Care

A final note is the stand that holds the screen. LCDs are made of thin glass plates that are easily damaged if they fall, so the stand must be strong and stable. Especially if you have kids who will be using the display, make sure the base is either fixed to a desk or heavy enough that it won't be easily knocked over.

Most LCDs can be tilted back and forth and some will swivel left and right or lift vertically, like Apple Computer Inc.'s new iMac, on an arm.

Ajay Gupta, vice president of desktop product development at Gateway Inc., suggests avoiding complicated bases. "Simplicity is the end game. We've debated the number of pivot points and find that a single pivot point is best," he says.

The greater the number of hinges, the more likely one is to jam or break, says Mr. Gupta. So, too, cables inside the base and arm can twist or fray if they are moved frequently, he says.

--Mr. McWilliams is a staff reporter in The Wall Street Journal's Houston bureau.

Write to Gary McWilliams at gary.mcwilliams@wsj.com