From dials to digits: to increase user friendliness and driver-vehicle interaction, instrument cluster displays must integrate more information into the same space and do so with high-intensity color, clarity and flair

Automotive Industries,  Dec, 2004  by Carla Kalogeridis

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A range of new solutions has emerged to meet the demands of the growing number of informational and entertainment displays in tomorrow's automobiles. As the trend moves away from dials to digits, opportunities abound for software and vehicle display technology suppliers.

"The current trend is toward the integration of graphics with gauges," says John Cramer, marketing and business development manager for OPTREX. "In this global automotive market, OEMs are interested in clusters without area-specific content. It's possible now for an automaker to have one IP for all its geographical markets and use graphics and software to alter the language from cluster to cluster."

Automakers can also employ a three-dimensional look in their clusters, he says. Background colors come from lamps on the ceiling of the instrument panel and are reflected in back behind the gauges. In addition, a new just-out-of-the-lab advancement from Optrex called field sequential technology features a series of colors that cycle through one frame at a time on the display, yet do so at a speed that makes it appear the colors are on at all times. The timing of the lamps and patterns flash off and on in sequence, Cramer explains, allowing the creation of a color display without color filters.

"The industry is definitely moving away from pre-printed appliques on gauges," Cramer agrees.

Bob Drury, director of engineering for Siemens VDO's IP Group, says another current trend is toward stand-alone center stack displays that feature a computer-like terminal. "We've already seen more integration of LCDs for driver-specific, turn-by-turn intelligence," he says. "Today's complete LCD displays are a fusion of digital and analog overlaid technology with large color. There is still a market for people who like to see gauges moving."

Yet, when it comes to vehicle displays, perhaps no advancement offers more promise in terms of greater contrast complexity, performance and packaging efficiencies than organic light emitting diode (OLED) technology. Currently, the growing range of specialty information requirements inside a vehicle is met primarily by liquid crystal displays (LCDs). Nevertheless, OLED technology is predicted by many as a viable replacement for LCDs in the next few years. "The development and progress of OLED technology is unprecedented in the display technology world," says Diane Rogers product manager for instrumentation, Yazaki North America. "There's no doubt in my mind that OLED will eventually compete head on with LCD."

"OLEDs are definitely coming," agrees Siemens-VDO's Drury. "There's already a pull toward OLEDs in Europe, which means it's only a matter of time before the technology arrives big in North America."

The benefits of OLEDs are numerous. OLED displays are composed of self-luminous pixels and require no backlights, using only five to six thin film layers to emit light. The technology provides clear, bright display and a full-motion, 180-degree viewing angle. In addition, OLED displays offer fast response times, high brightness levels in a variety of lighting conditions, low voltage and power consumption, cold temperature operation and thin design options. In addition, OLEDs are potentially suitable for curved applications in IPs with 3D contours. While many companies have begun using OLED technology in mobile phones, digital cameras and automotive after-market audio products, it is estimated that the size of the OLED market could grow to more than $1.7 billion within the next several years.

"OLEDs offer higher levels of integration, higher density and more pixels in a given area," says Cramer. "Although certain design rules still specify which technology is used in a given vehicle, OLEDs are just emerging in North America." Cramer says the industry will see more OLED installations in 2006 and 2007, as more OEMs recognize the greater complexity achievable with OLEDs and the trend moves from monochrome to full color and higher resolutions.

Unfortunately, OLED technology is not without its shortcomings. The self-luminous colors don't last as long as required to be viable in the automotive market. (Length of life is not so important for cell phones because they are replaced in 6 months to a year, but vehicle owners will expect their displays to work for 15 years). In addition, the technology does not perform well in high temperatures, and it is still more costly than LCDs.

The short lifespan can be blamed partially on the fact that the OLED material decays if exposed to moisture. OLEDs, like LCDs, are housed between two pieces of glass requiting the display to be flat. Replacing the glass with plastic would enable curved displays," Rogers says. "Light-emitting material doesn't last very long with plastics," she says. "It's the same reason that you don't buy beer in plastic bottles--it goes flat. We have to find a way to seal plastics so moisture doesn't get in."