Mobile Computing Tips: Spotlight on Notebook Displays

We analyze the three type of notebook screens--in plain English.

James A. Martin

Feature: Mobile Computing FAQ--Notebook Displays

When it comes to notebooks, the phrase "put it where the sun doesn't shine" is apt. Portable computers allow you to work any time, anywhere--except in bright daylight, where the screen loses all contrast and becomes unreadable. This has left many of you with the following question.

Q: Why does my notebook display wash out in bright sunlight?

A: Because your boss doesn't want you goofing off in the park, silly.

Actually, the answer is more involved, though it all has to do with lighting. There are three types of LCDs (liquid-crystal displays) used in today's notebooks, PDAs, and other portable gadgets: transmissive, reflective, and transflective. I could get really techie describing how these technologies differ, but I'll spare us both the pain and just get to the heart of the matter. Read on for the 411 on the three screen types.

Good Images: Transmissive

The overwhelming majority (like, 99.9999 percent) of current notebooks feature transmissive, color, active-matrix LCDs. That's because transmissive screens offer the best-quality images and are the most affordable option for manufacturers.

Transmissive LCDs are illuminated by fluorescent backlighting and are capable of rendering the greatest color depth, sharpest text, and highest resolutions. The backlighting is a major drag on a notebook's battery, however. And it's easily overpowered by bright sunlight.

"If you shine two lights at each other, the stronger will overpower the weaker," explains Bob O'Donnell, research director for device technology (including LCD screens) for IDC in Mountain View, California. With transmissive screens, backlighting automatically takes a back seat to sunlight. The result is that transmissive screens become nearly unreadable, with little discernible contrast, when exposed to sunlight.

Because of their high quality indoors, though, transmissive color screens have become the most widely produced displays for notebooks and desktop flat-panel monitors. Like any technology, the more transmissive color screens produced, the less costly the displays are to make. And because most notebook users work indoors, it only makes sense to give them the best, least expensive display technology for the job.

Good Outdoors: Reflective

A reflective screen forgoes backlighting in favor of a mirror that reflects ambient light to illuminate the display. As a result, reflective screens are ideal for use in bright sunlight and use the least amount of battery juice. The downside? You guessed it: Reflective screens are typically dim when viewed indoors, which severely limits their use.

With its illuminated reflective screen, NEC's Versa E120 DayLite notebook is an exception to the rule. NEC's notebook, designed for viewing outdoors and only "occasional indoor use," as the company's marketing brochure states, features a switch that turns on the screen's backlighting. For more information, read my hands-on evaluation of the DayLite's dual-mode screen in this issue's Notebooks section.

Somewhere in Between: Transflective

Transflective (or transreflective) LCDs are a kind of hybrid between transmissive and reflective screens. Indoors, transflective screens use backlighting to render images. Outdoors, transflective screens are still legible, because they absorb the sun's rays to produce a bright, readable image (which also saves battery power).

Typically, transflective LCDs render good-quality color and images, but they can't measure up to the high resolutions and sharp images that transmissive screens produce. And because they lack the economies of scale that transmissive screens have, the majority of notebook manufacturers don't see transflective LCDs as a practical option.

There are exceptions, however. Some Panasonic ToughBook notebooks--ruggedized portables for markets such as law enforcement--feature transreflective screens. The ToughBook 28, for instance, is available with a 13.3-inch XGA transmissive, touchscreen, active-matrix color LCD capable of 1024 by 768 resolution or with a 12.1-inch transflective, touchscreen, active-matrix color LCD capable of 800 by 600 resolution. But a 13.3-inch transmissive-screen ToughBook costs $200 less than a similarly equipped model with a smaller transflective screen. For more information about ToughBooks, see "Panasonic Unveils Tougher ToughBooks."

Small transflective screens are often found in today's PDAs, in both color and monochrome versions. Hewlett-Packard's IPaqs feature color transflective displays, for instance, while the Palm I705's screen is monochrome transflective.

In the future, the growing popularity of wireless networks (see the Wireless section) may spur notebook makers to offer more models with transflective or reflective screens, says IDC's O'Donnell. For now, though, most mobile workers will need to stay inside to get their work done. (I've got an inexpensive workaround to the problem, though; see my tip in the Notebooks section.)

Notebooks

Hands On: NEC's Notebook for Outdoorsy Types

I love to get out on a beautiful day, but I have to make a living, too. So any device that promises to let me work outdoors, such as NEC's Versa E120 DayLite notebook, immediately gets my attention.

Unlike other notebooks, the DayLite features an illuminated reflective screen that's designed to be at its most legible in bright sunlight. By comparison, the vast majority of notebooks today feature transmissive screens, which produce crisp, bright images inside but lose all contrast outside. (See this week's feature for an explanation of LCD technologies.)

While evaluating the DayLite, I came to admire many things about it: its light weight (about 3 pounds), three USB ports, FireWire port, built-in Ethernet, and more. But its screen wasn't one of them.

The 10.4-inch display can be positioned flat, parallel to the keyboard, which provides a wider range of viewing angles than most notebook screens offer. But no matter where I positioned the screen, there were always dark areas, even with a bright sun at my back.

The areas directly in the sunlight were the most legible. I could easily make out details and colors of digital camera images, for instance, when the sun was directly on them. As for areas in shadow, or that got indirect sunlight, the screen's antireflective coating proved distracting. In addition, the top and bottom corner areas were too dim for comfortable viewing.

When you're indoors, you can toggle a switch to you turn on backlighting, but the screen remains dim--even with the brightness control set to maximum.

At $2129, the DayLite is fairly pricey for an 800-MHz Pentium III ultra portable. You get 256MB of memory, a 20GB hard drive, an external CD-ROM drive, and a choice of Microsoft Windows XP Professional or Windows 2000 Professional--but no Office applications are included.

Still, because you can read at least some of the screen outdoors, the DayLite is worthy of consideration by digital photographers, mobile workers, and other professionals who frequently need a computer outside. The DayLite might also serve as their primary computer, but only if an external monitor were attached and there was no need to use the DayLite indoors when traveling. For someone like me, though, who needs the flexibility to work anywhere, the DayLite isn't the answer. I'll stick with my 11-year-old laptop, thank you very much (see the next item).

For more information about the DayLite, see "NEC Revamps Notebook for Outdoors." For current prices, go to the PCWorld.com Product Finder.

Tip: For Outdoor Computing, Try an Old Mac

Most Palm and Pocket PC screens are designed to be readable indoors and out. In a previous newsletter, I explained how to configure a PDA with a full-size keyboard and Office-compatible applications to work anywhere.

But their small screens make PDAs uncomfortable for any extended work. So when I need to get out and work a while, I pack an 11-year-old Macintosh PowerBook. Introduced in 1991, the PowerBook 170 remains, in my opinion, a laptop classic. The crisp, active-matrix, black-and-white screen can be backlit while inside for optimal viewing. Outside, just slide a bar to turn backlighting off (and conserve battery power), and you've got a terrific word processor or Excel spreadsheet cruncher to use by the pool.

Yes, the PowerBook 170 is slow. And of course it's terribly outdated. But you can pick one up on EBay for less than $100, often with Word and Excel-compatible applications already installed. A program such as DataViz's Mac Opener 2000 allows your current Windows PC to read a Mac-formatted floppy, onto which you can shuttle Word, Excel, and other files back and forth from the PowerBook. Mac Opener 2000 is available for $50 at the DataViz site.

News: Mobile PCs on the Rise

If you start seeing more people traveling with notebooks, don't be surprised. During the second quarter of 2002, worldwide mobile PC shipments increased 6.1 percent, compared to the same period last year, while overall PC shipments around the globe dropped 1 percent, according to a study by Dataquest, a division of Gartner. Dell and HP were in a virtual tie for the most notebooks shipped, the study reports.

Handhelds

News: Got Fuel?

PDA and mobile-phone users will get a charge out of this: a direct methanol fuel cell about the size of a deck of cards, capable of letting small gadgets run nearly ten times longer than they can now. MTI Micro recently unveiled a fuel-cell prototype that will recharge your device's lithium-ion battery. That's the good news. The bad? A commercial version won't be available until 2004.

Tip: How to Decide on a PDA

Palm or Pocket PC? It can be a jungle out there in PDA Land as you try to figure out which handheld device deserves your dough.

But here's a handy rule of thumb, courtesy of our "Buyers' Guide to PDAs": Just want to maintain an up-to-date calendar, contact database, and to-do list? Palm OS devices have the edge here for their easy-to-use data synchronization. Need to carry a lot of Office files with you on the road? Pocket PC devices handle PC-like apps better than Palm handhelds, yet still offer scheduling and contact synchronization.

Tip: Web Site for Bargain Hunters

Not long ago, you could knock $100 off the price of a Toshiba E310 Pocket PC using two $50 rebates available at Amazon.com (one rebate has since expired). The company was also offering Toshiba buyers a free $50 gift certificate, good for Amazon.com purchases, a free 32MB Secure Digital card, and if all that wasn't enough, free shipping. How do you find bargains like this? By trolling Techbargains.com, a Web site that compiles info on the latest price drops, rebates, coupons, and other money savers for gadget lovers.

Wireless

News: Wireless Networks Growing

Wireless networks based on the IEEE 802.11 (Wi-Fi) standard are on a roll. The global demand for Wi-Fi products will grow from $1.2 billion in 2001 to $3.1 billion in 2006, according to research company Dell'Oro Group. Wi-Fi networks will be particularly popular in small businesses and homes. Declining prices for Wi-Fi home networks, which allow users to share broadband connections among multiple PCs, is one reason why wireless networks will grow in popularity.

Confused?

Have you ever mistaken a Wi-Fi hot spot for a cold boot? Send your questions about notebooks, PDAs, and wireless services to james_martin@pcworld.com for possible publication (with answers, of course) in future issues of this newsletter.