New display technology called into active service for multimedia

It used to be that assembling a multimedia presentation was the hard part of the job, with hours spent synchronizing sound, video and animation, tweaking text and making sure color palettes for graphics didn’t clash.

While tools for creating multimedia presentations have flourished in the past year, tools for displaying presentations from a computer to an audience, particularly a large audience, have evolved much more slowly. Among the more promising of these evolutionary paths is the growing popularity and availability of color flat-panel displays based on active-matrix technology, also known as thin-film transistor (TFT) technology.

Not a projector. To date, multimedia producers have basically had three choices for displaying their multimedia presentations: outputting the presentation to videotape; using a three-beam (red, green, blue) CRT (cathode ray tube) data projector; or opting for an LCD (liquid crystal display) projector.

Each technology has its problems. Most multimedia producers feel the degradation in quality from computer screen to video does not do their presentations justice. And video is not a viable option for those who require interactivity.

Data projectors, from companies such as Barco, NEC Technologies, Sony, Panasonic and PDS Video Technology, get the job done: these devices project beams on a wall, displaying a color image that is on average up to eight feet across and that provides a one-to-one correspondence between the computer screen and projected image. But data projectors are for the most part bulky and expensive (costing anywhere from $8,000 to $22,000). In addition, the user must be familiar with the projector in order to converge the RGB (red, green, blue) beams.

You need a specialist. In addition, not all computer graphics cards work with all data projectors. Since many multimedia producers don’t own data projectors, an audio-visual specialist is required to help set up the system.
LCD projection devices — flat panels that are placed on overhead projectors — are inexpensive, lightweight, portable and easy to set up. And in a time when computer users are becoming more aware and concerned about radiation emissions from CRTs and VDTs, LCD displays are an attractive alternative. LCDs are non-emissive; they do not create their own light, as do CRTs, but rather reflect and block light.

But LCD projection panels have generally been limited in color (with models ranging from 64 colors up to 5,000) and considered too slow to process animation and multimedia presentations because of the passive-matrix technology they use.

ENTER ACTIVE-MATRIX TECHNOLOGY

In a passive-matrix LCD display, a grid of square pixels is formed when the intersections of horizontal and vertical wires are lit up with electrical charges.

But with active-matrix (TFT) technology, a transistor drives each pixel, amplifying the electrical charge. This results in a high-contrast image. Because each pixel is individually controlled, the scan rate for the panel is also much faster than with passive displays. The faster scan rate also eliminates a problem commonly associated with passive LCDs called bleeding, where a shadow shows up near light or dark areas on the screen.

Every transistor counts. The major problem with active-matrix technology is also its most significant advantage: every transistor counts. On the small-screen LCD televisions manufactured by companies such as Panasonic, for instance, if a red, green or blue sub-pixel doesn’t fire occasionally, you probably won’t notice because the picture is constantly changing. On a computer screen, however, a bad transistor might change the content of the data — particularly if it shows up as an unintended decimal point in a spreadsheet.

To the manufacturers of active-matrix LCD panels — Sharp, Hitachi, Seiko/Epson and Toshiba (in a joint venture with IBM) — if a panel has a single defective pixel, it is unacceptable. For this reason, the production yields on active-matrix displays are low and the price per panel is high.

Manufacturers are beginning to address this low-yield problem by including extra transistors within each pixel, and in the somewhat near future, prices for active-matrix panels should come down.

They aren’t cheap. The Toshiba/IBM venture, Display Technology Inc., develops color flat-panel displays; a 10.5-inch display for laptops sells for about $3,000. And active-matrix displays are already being used in laptop and notebook computers by companies such as Apple, Toshiba and NEC, according to Joseph Castellano, president of Stanford Resources Inc. (San Jose, CA), whose firm specializes in electronic display technologies.

“The trouble is they are expensive, with [color display-equipped laptops] costing $5,000 to $6,000,” says Castellano. “Manufacturers haven’t been getting good yields, so machines are available only in limited quantities. But you’ll start to see more of them in 1992.”

OFF THE LAP, ONTO THE WALL

In the past year, two LCD projection panel vendors have released active-matrix LCD panels capable of displaying color animation and multimedia presentations.

Newport News, VA-based nView Corp. has released the MediaPro, a $9,995 lightweight LCD projection panel that can display both standard color video and computer-generated graphics from up to four sources.

Supports four sources. The 6-inch, 8.75-pound MediaPro can be hooked up to four computer and video sources simultaneously. It accepts composite, analog RGB and S-Video signals and a computer’s digital signals. It displays both Macintosh II and DOS PC graphics and animations, as well as live-motion video from devices such as laserdisc players, VCRs and video cameras. The device supports international video standards, including the U.S.’s NTSC, Europe’s pal and France’s SECAM video signals. Users can easily switch between sources throughout a presentation by using a remote control wand.

The MediaPro is placed on top of an overhead projector, which then projects the image on its panel onto a wall. It supports a resolution of 6405480 pixels in VGA, Macintosh II and video modes.

Fast enough for video. The MediaPro supports 32,000 colors and uses nView’s proprietary built-in software to enhance the active-matrix display. The combination of color and nView’s firmware allows the panel to display high-contrast images and offers a fast enough response time to display live, full-motion (30-frame-per-second) video with non-smearing motion, according to John Kupiec, nView’s vice president of product development.

“We were an early adopter of TFT technology and released our first product in March 1991 after the color TFT panels became commercially viable, not in huge quantities but in important quantities,” Kupiec said. “For so many years, people have talked about the flat TV set on the wall. The active-matrix LCD will probably put that technology on the wall, and we think the first versions of it will be projected.”

Monitor quality on the wall. Kupiec agrees that active-matrix technology is costly, but he notes that corporate clients — “early adopters” themselves — are already paying to use it for business meetings, sales demos and training sessions. “Our products are not inexpensive, but we sell a lot of product. There is a demand among people who are willing to pay extra dollars because they want a portable, lightweight display that puts monitor-like quality on the wall.”

MediaPro is actually the second LCD alternative to offer both graphics and video projection. In June, Proxima Corp. (San Diego, CA) began shipping Ovation, an active-matrix LCD that sells for $8,495.

Weighing in at six pounds, Ovation supports up to 24,389 colors and allows users to connect it to two sources, including a pc- or Mac-based system and an NTSC- or pal-compatible video device. Like the MediaPro, Ovation is used in combination with an overhead projector; you switch between signals using a handheld remote control.

THE COST OF THE CUTTING EDGE

Although LCD projection panels are lightweight and easily transportable, their cost may still seem prohibitive to multimedia producers. Kupiec and Castellano agree that costs will go down as manufacturers begin to get better yields, but that time may still be two to three years away.

Another factor that may keep prices high is a recent tax imposed on foreign LCD manufacturers. Many U.S. vendors buy their active-matrix panels from the Japanese; the U.S. International Trade Commission (ITC) –with some prodding from the U.S. Department of Commerce, which in turn was prodded by several small U.S. manufacturers of LCDs — recently decided to impose a 62.67 percent tariff on active-matrix displays.

The tariff’s intent is to discourage dumping, but since no U.S. companies are presently manufacturing the color TFT screens, no alternative is available. So, as nView’s Kupiec says, “When it comes to price, we’re at [Japan's] mercy.”

At the mercy of the overhead, too. In addition to the price barrier, no matter how fabulous a TFT display is, presenters are also at the mercy of the onsite overhead projector’s lens quality and the amount of light it emits. The image created by a $9,000 TFT projection panel, projected with an old or cheap overhead, will look awful.

In addition, while both the MediaPro and Ovation can reproduce the color and resolution of the computer screen, the projected image sizes for LCD panels range from six to 12 feet diagonally — after 12 feet, the image loses focus — with a 1:1 viewing ratio (i.e., a six-foot image looks best when you’re six feet away from it, etc.). And LCD panels — active-matrix or not — can’t amplify sound. If you have sound in your multimedia presentations, you still need to have speakers and/or a microphone hooked up to your computer to project it.

Connie Guglielmo