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.
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 threedimensional look in their clusters, he says.
|Yazaki incorporated OLED technology into the new Aston Martin DB9’s instrumentation cluster and infotainment control module. |
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 appliqu?s 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.”
|The 2005 Corvette (shown) and Jeep Grand Cherokee both incorporate OLED technology in their display modules. The OLED modules are made at ADEON in Tokyo, a joint venture between Optrex and Nippon Seiki.|
| The Siemens VDO Automotive instrument cluster for the Mercedes-Benz E-Class features an informational LCD placed directly in the center of the dial over the revolving disc assembly, allowing the speedometer pointer to travel round the centered LCD.|
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 aftermarket 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 requiring 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.”
Rogers says it would help if the testing rules for comparing OLEDs and LCDs were revised. Traditional displays like LCDs were used to create the standards which are specified independent of temperature. “Life for an OLED display may be shorter at extremely high temperatures, but realistically, how long will a driver use the display while sitting inside a vehicle at 85 degrees C? Also, each color has a different lifespan allowing adoption of some colors before others. Not all OLED colors are developed,” she says. “You can’t match the ‘Pontiac Red’ with OLED because that color material isn't yet available.”OLED Debuts
Yazaki’s first automotive application of OLED display technology appears in the new Aston Martin DB9. Yazaki incorporated OLED technology into the DB9’s instrumentation cluster and infotainment control module.
With the DB9, Aston Martin wanted to pay particular attention to the appearance of the driver communication products. Having seen examples of the work Yazaki was doing with OLED technology, Aston Martin challenged the supplier to create a unique instrumentation cluster for the DB9.
The DB9’s WatchDial cluster face contains components that give the appearance of a brushed metallic look that was created by using in-mold metallic foil on plastic. When the watch dial is lit, the tick marks appear as lit jewels. Each tick is part of a prism with vacuum deposition of aluminum onto the surface. The end of the plastic is then cut at an angle and inserted through the openings in the outer ring. Each overall dial is floodlit from above within the cluster. A final element of the cluster’s design includes a unique tachometer needle: the speedometer has a clockwise movement, while in a break from the automotive norm, the tachometer moves counterclockwise.
OLED displays, manufactured by ADEON, a joint venture between Optrex and Nippon Seiki formed in 2003, are incorporated in the clusters of the 2005 Chevrolet Corvette and the Jeep Grand Cherokee. The blue-green display areas below the word CORVETTE, and gear shift and driver door open displays on the Jeep Grand Cherokee are both OLED modules.A Bright Future
Most suppliers agree that it’s only a matter of time before OLED technology overcomes its weaknesses in temperature and lifespan, and OEMs are already excited about the new design possibilities with OLED.
“In a couple of years, OLED cost will match that of LCD,” predicts Yazaki’s Rogers. “Add that to the technology’s presumed ability to address its temperature and lifespan challenges, and you’ve got an exciting new design tool for automakers and drastically improved vehicle display performance for the driver.”