As Mobile Displays Boom, Innovations Continue
by Jyrki Kimmel
Mobile displays have transformed from the early, simple alphanumeric and monochromatic passive-matrix LCDs to full-video-capable multimedia displays that boast some of the leading characteristics in displays found today. The increasing demand for space savings, robustness, reduced power consumption, and improved image quality in an environment of rapid cost erosion presents trade-offs that are difficult to solve for any display provider – yet the market is booming. This is due to the proliferation of mobile phones in all markets worldwide, including previously inaccessible third-world countries where a mobile infrastructure is rapidly being deployed.
In the developed countries, mobile multimedia delivery to cell phones has become a hit. Multimedia in this context includes music videos, TV broadcasts, movies, and navigation applications, all of which demand high image quality on the display under various ambient-lighting environments. The entry point for many of these services is the Internet, and to access Web pages comfortably, highly legible displays are required. The entire mobile user interface is therefore a major focus of development, as can be seen in products that are coming out from major manufacturers. These include devices with touch screens and other advanced interaction capabilities. One challenge remains in "pocketable" devices, since one cannot stretch the screen size beyond the limits of the phone frame with current commercially available displays. The main dilemma is how to present all the information required by the mobile user in a virtual screen size that is significantly larger than the dimensions of the device itself.
One solution to the dilemma is to use head-worn displays, such as "goggles," that show the image by enlarging the view from a microdisplay. The early attempts at making these devices were not successful due to the bulky optics, which resulted in cumbersome devices with uncomfortable, nose-heavy weight distribution. They also must be tethered to the main device that is responsible for the reception, storage, and display of the content. Current radio interfaces cannot reliably deliver full video to a VGA resolution display, and thus the user needs to be wired to the device.
Another problem is the interaction paradigm with which the user is expected to control the mobile device. Touch input on the main screen is one obvious solution that is finding use in many forms. With head-worn displays, however, new ways of interfacing the user with the control of the device are required.
With respect to integrating displays into mobile devices, significant developments have taken place to ensure data delivery to the display module by adopting high-speed serial interfaces. With advanced interaction capability being integrated in the display itself, the back channel also becomes a problem to be solved, which future interfaces will address.
The three feature articles in this issue of Information Display describe the mobile-display market, interaction mechanisms, and the electrical interface development. First, Jeff Brown from Portelligent describes the effect that mobile smart-phone development has had on the small-to-medium–sized display market, including trends in phone form factor and the integration of touch screens. Overall, it seems like a boom for the small-display makers, even though the cost pressure remains high.
In the second article, Toni Järvenpää from the Nokia Research Center illuminates a facet of research that has taken place in the past few years to develop a solution for the head-worn-display interaction problem. Gaze tracking is integrated in a diffractive optics module that provides the image from a microdisplay to the user. The result is a compact gaze tracker that is registered with the image path automatically, demanding only a single calibration for each user.
Lastly, Jim Schuessler from National Semiconductor describes the developments in the electrical display interfaces for mobile devices. The demands on the display interface have resulted in extensive standardization of these interfaces, and the industry needs to collaborate to develop the standards to reflect the future needs of mobile-device users.
The Society for Information Display (SID) is well abreast of the trends in mobile displays. The 2008 SID Symposium had quite a few papers on mobile displays, and the Display Week Exhibition presented vendor offerings from the main players in the field. In addition, the Journal of the SID publishes papers on mobile-display research. In fact, in the November 2008 issue of JSID there will be a special section on mobile-display research papers. In September, SID organized the third Mobile Displays Conference held in San Diego, a further indication that there is a demand in the industry for sharing information on mobile displays. Finally, in May, the SID/Wiley book series published a textbook on mobile displays. All this activity in SID on mobile-display aspects, starting from basic research and ending up in industry offerings to the device integrators, shows that not only is there a business demand outside the large-area glass industry, but that major breakthroughs are appearing in the mobile space as well. •