Return to May 25, 1998 table of contents

Cheryl Ajluni

Where does one go for the latest information on anything and everything to do with displays? The answer is simple: the 1998 Society for Information Display (SID) international symposium, seminar, and exhibition, scheduled for May 17-22 at the Anaheim Convention Center in Anaheim, Calif. With a line-up of over 350 papers, nearly 400 exhibitors, and a slew of day and evening short courses, seminars, and panel sessions, there is something to appeal to every attendee's level of interest (see the table). As Russel Martin, Principal Scientist at Silicon Image, Inc., San Jose, Calif., and General Chair for SID '98 explains, "The conference has become the leading international forum for advances in electronic-display products, technology, systems, applications, manufacturing, testing, and human factors."

As a result, it seems only fitting that new information on displays--information that will help to change how we live, work, and play--will be delivered near the home of "the most magical place on earth"--Disneyland. And, in keeping with this theme, attendees will be treated to keynote addresses from Hisashi Yamada, Toshiba Corporation, Kawasaki, Japan, who will describe Digital Video Disk (DVD) technology and explore its many applications, and Eric Haseltine, Vice President and Chief Scientist of Walt Disney Imagineering, Anaheim, Calif., who will speak on the continually increasing possibilities for using computers in entertainment.

One of the new items at the show is a Display Technology Showcase. The object of the showcase is to feature side-by-side comparisons of different display technologies intended for similar applications, and operating from the same signal sources.

Some of the technologies that will be featured at the Display Technology Showcase include large video and graphics displays using plasma, liquid-crystal dispaly, cathode-ray tube, and front- and rear-projection technologies; medium to medium-large monitors using a variety of technologies; LCD monitors using TFT, standard STN, and enhanced STN technologies; medical displays; and small datagraphic displays using LCD, FED, LED, and EL technologies.

Display Technology Advances

In recent years, the maturation of the display industry has been dominated by three factors: the demand for more display-based consumer products; the drive toward lower-power, higher-performance portable display technologies; and the call for large- area, low-weight display technologies driven by HDTV and wall-hanging television applications. Not surprisingly, the trends at this year's show are no different.

On the consumer side, an interesting technological development known as the reverse emulsion electrophoretic display (REED) comes from researchers at Zikon Corporation, Campbell, Calif. Basically, it's a flat-panel display (FPD) technology (which utilizes the electrophoretic properties of reverse emulsions) that's being eyed as a viable alternative to LCDs (Liquid Crystal Displays). In its continuous or non-polar phase, this emulsion is a clear liquid. Its polar phase is a liquid that can be colored with virtually any dye as long as it is soluble in a polar solvent and insoluble in the non-polar phase. To form a stable suspension of colored droplets inside the non-polar phase, detergent is used to form micelles containing the polar phase. These colored micelles can then be electrically charged, or otherwise responsive to electric fields, depending on the specific components chosen.

To form the display, this reverse emulsion is injected into a sealed cell. The cell is comprised of two glass plates with etched ITO (Indium Tin Oxide) electrodes. By applying voltages across the emulsion through the ITO electrodes, the color of the display can be changed.

As compared to LCDs, the REED offers higher performance in transmissivity--in excess of 70%, a wider viewing angle, and increased color brightness. The technology also offers lower power consumption, low material cost, is inexpensive to produce, easier to fabricate, and has the potential to display full colors. Further details of this development are highlighted in paper 47, "Reverse emulsion electrophoretic display (REED)."

One of the major factors driving the development of low-power, high-performance portable display technologies is the growing popularity of portable laptop computers and cell phones. To answer this need, a joint team of researchers from Sarnoff Corporation, Princeton, N.J., and Thomson-LCD, Moirans, France, have developed an 8.4-in. a-Si AMLCD (amorphous silicon active matrix liquid crystal display). With a pixel size of 204 µm by 202 µm and an aperture ratio of 45%, it is the first a-Si display designed for direct-view applications, and the largest built to date with integrated row and column drivers.

As summarized in paper 148, "Sub-notebook a-Si color SVGA display with integrated drivers," the large-area a-Si AMLCD, with on-board scanners, uses a sample-and-hold column driver with a threshold autozero function. This allows for uniform column charging and an increased data- sampling interval. The row drivers incorporate previous line storage with circuitry to reduce horizontal crosstalk. Transistor threshold drift cancellation circuits also are used to extend lifetime. Special bussing techniques are used to help reduce power dissipation.

By now, almost everyone has heard about the coming of HDTV (high-definition television). What we haven't heard is when it will arrive. Part of the problem is standards related and the other part stems from lack of mature technology. One of the most promising candidates for HDTV is PDP (plasma display panel). But until now, they have lacked the higher resolution, larger display area, and higher picture-quality characteristics required by the consumer TV and HDTV markets.

Researchers from NEC Corporation, Kanagawa, Japan, think they have changed all this with the development of a high-contrast 50-in. color AC plasma display. As detailed in paper 165, "High contrast 50-in color AC plasma display with 1365 x 768 pixels," the display features 17 million colors and can display both HDTV (Hi-Vision) and XGA (PC) images with a 350:1 dark-room contrast ratio. This latter feature is made possible by the use of a single priming drive sequence. The PDP also uses an improved capsulated color-filter technology and features a wider color array than the more traditional CRT.

NEC's display monitor is a mere 97 mm in depth--despite its 50-in. diagonal area, and has an aspect ratio of 16:9. Using a dual-scan technique, the panel can be driven in 8-bit gray levels without miswriting. A scaling IC converts the Hi-Vision signal to 768 progressive scan data allowing the panel to reproduce vivid high-definition moving pictures.

One problem with the conventional CRT is that its curved face can cause distorted images when viewed from the side, as well as unwanted reflections from ambient light. Thanks to researchers from Mitsubishi Electric Co., Kyoto, Japan, these problems have now been solved with a perfectly flat face color-display tube. As detailed in paper 236, "Development of perfectly flat face color display tube DIAMONDTRON NF," this tube features high brightness and high resolution, is distortion free, and allows for natural-looking flat images. Because the tube is flat, the reflection and glare caused by ambient light is significantly reduced.

The DIAMONDTRON NF tube was developed using an accurately calculated polynomial curve based on typical usage environments and human vision characteristics. It incorporates a host of new technologies including a tempered glass bulb, flatter aperture grille, and a new electron gun. Its surface is treated with an anti-reflection coating.

Emerging Applications

One exciting feature of the SID show is that it affords attendees the opportunity to get a first glimpse at some of the more innovative uses of display technology; especially as it pertains to consumer products. An interesting development in this area comes from a joint effort by Jaguar Cars Ltd., Coventry, England; Texas Instruments (TI), Dallas; and Pilkington Optronics, Glasgow, Scotland, to develop an automotive Heads Up Display (HUD). The system, which uses a HUD to project an enhanced image into the drivers line of view, incorporates a variety of technologies including Pilkington's optical modules, and TI's digital near-infrared (NIR) CCD camera.

The project, summarized in paper 97, "Evaluation of flat panel display technologies for an automotive night vision enhancement HUD system," came about as a result of human factor trials done by Jaguar indicating that night vision systems can dramatically improve automotive safety.

The way the system works is that a set of filtered car headlights illuminate the scene ahead of a vehicle with NIR radiation. A NIR-sensitive digital CCD camera images the scene and exports the data to a DSP. Here, the image is processed and presented to the display. The HUD display module then projects the image off a partially reflective combining element. The image becomes superimposed on the real view through the windshield and is focused at a point in front of the vehicle. To a driver looking through the windshield, what they would see is an enhanced image overlaid onto the real forward view.

Work on this system is now focused on the use FPDs, as opposed to CRTs. This could lead to substantial improvements in performance while reducing volume, complexity, and unit cost. A production-intent prototype of the system is expected to be developed next year.

Medical Imaging

In the medical arena, researchers from the X-ray Imaging Research Laboratory, Henry Ford Health System, Detroit, Mich., have developed a computational method for examining the effect of rough surfaces and anti-reflective thin-film coatings on luminance spread functions. This is an especially critical capability for medical imaging applications where images with wide luminance range and low contrast detail are displayed.

To achieve the required display quality for medical applications, careful control of the light transport processes in the faceplate of CRTs is needed. But, the luminance range of CRT systems is limited by the glare associated with light diffusion in the thick glass faceplate.

One way to deal with this problem is through the use of an optical Monte Carlo simulation code (DETECT-II). This code, written in FORTRAN 90, can effectively model the luminance spread in emissive structures. Specific details of the code are presented in paper 260, "X-ray Monte Carlo modeling of glare in cathode-ray tubes for medical imaging."

Eyeglass Displays

A new approach to the design of an eyeglass-based display is highlighted in paper 250, "Optical approaches to incorporation of displays within eyeglasses," from The MicroOptical Corporation and Northeastern University, both of Boston, Mass. The approach incorporates the optical relay between the display and the eye within the eyeglass lens, and the display within the eyeglass temple. This design offers an eyeglass appearance that is acceptable to the user. Such an advance is significant since the development of wearable computers requires a portable display that is light-weight and low power, and that can be operated without requiring the use of hands.

The system uses a 0.25-in. diagonal, 320 X 240 pixel format AMLCD, and an optical relay built into the frames. The display and backlight are mounted within the temple of the glasses. The image is provided to the eye by the optical relay mounted within the eyeglass lens. When the display is turned off, the system reverts back to ordinary glasses. A cable runs through the temple that connects the analog AMLCD to drive electronics. The electronics receive standard VGA signals and convert the data to the format required to drive the 320 X 240 display. A monochrome version of this eyeglass system has already been developed, with a color version currently being developed.

Anyone looking for more information on display technologies or a glance at some the latest display-based products should look no farther than SID. For more information on the conference or to register, contact Mark Goldfarb, Palisades Institute for Research Services, 201 Varick St., Suite 1006, New York, NY 10014; (212) 620- 3380; fax (212) 620-3379

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