Electronics brighten outlook for lighting; suppliers are adding value to lighting systems by using electronic controls

Automotive Industries, July, 1998 by Mark Phelan

Suppliers are adding value to lighting systems by using electronic controls.

The future of electronics in lighting is so bright, you've gotta wear shades. As automakers put more emphasis on creating distinctive interiors, they look to electronics to add functions and reduce the size of light modules.

Over the next several years, lighting suppliers will use a variety of electronic components to redefine the capabilities and physical properties of their components. The changes encompass interior and exterior lighting, and include controls, power modulation and packaging.

One of the first advances to reach the market will be an electronically controlled dome lamp from Cooper Automotive for a 2000-model car.

"There's already a good marriage of switches and electronics, but it hasn't reached the auto industry," says Bill Buchman, Cooper director of OEM sales. Cooper hopes to remedy that by bringing soft-touch controls -- common on microwave ovens -- to interior lighting.

The electronic switches have an actuation depth of just 0.5mm, and the total control unit -- switch and underlying circuit board-- may be as thin as 2mm. That compares to switch depths of 16mm to 25mm for current mechanical switches, he says.

It's easy to add functions with electronic switches, Buchman says, citing opera lighting, variable brightness for each bulb in the assembly, and configurable control panels for different models. Controlling all those functions from a chip in the light housing rather than the body controller simplifies both the wiring harness and demands on the body controller.

On the other hand, running several lighting functions from the body controller or a single lighting-control module offers some benefits, says Joe Fadool, Siemens Automotive marketing manager, electrical and electronic distribution systems. The module could regulate voltage to all the bulbs in a system and provide diagnostic features at lower cost and complexity than current systems.

"You can also program a lighting-control module for the requirements of different countries, rather than having a different set of parts for each country," he says. While Fadool is intrigued by the possibility of integrating other functions -- anti-theft, warning chimes, fuses, switches -- into the "we have to cost," he says. Separate controls may make sense for multifunction interior lights, while exterior lights might run off a single controller, he says.

Such central control will help make high-intensity-discharge (HID) and neon lamps less costly and more common, says George English, director of lighting systems for Siemens' OsramSylvania unit. Today's costly HID lamps rely on sophisticated ballasts to regulate the current they receive from vehicles' relatively imprecise electrical systems. "Half the cost of a ballast comes from regulating current," he notes. Those functions will move from the ballast to the car, as other components also require more closely controlled voltage.

Electronic controls will keep those high-voltage lights from interfering with the other electronic systems, says Tom Gioia, Visteon director, electronic component engineering. "It's important that these powerful lights are good electrical citizens." Visteon is also looking at electronic controls to vary headlight illumination depending on the ambient light, vehicle speed, road surface and cornering attitude.

The growing emphasis on interior design will lead to a greater emphasis on controlling interior lights, predicts Michael Buford, president of Hella North America and Hella Electronics. "Electronics will play a big part of that because the lights must do more than just illuminate," he says. "They must be functional, with dimmers or voice-activated lighting. We're also looking at proximity activation, so that if you reach close to where the switch is, the light comes on."

Sensors will also play a large role in interior lighting, he says, varying illumination depending on glare or ambient light.

Hewlett-Packard is also working on interior light with its LED lamps, says Dave Zabrowski, manager, automotive lighting. "Moving away from bulbs to LEDs for instrument panel lighting can reduce the depth of an instrument cluster from 100mm to 150mm, to just 7mm to 10mm. That frees up space for air bags, CD players or other features." With multi-chip controls, a single LED could produce any of several colors, reducing manufacturing complexity, he says.

However, none of these sophisticated controls make sense for a simple on-off lamp, so the automakers will use them as differentiators in upscale vehicles. "We must raise the customer's perceived value with more convenience features and greater reliability," Visteon's Gioia says.