SAE 2001: Gentex Auto High-Beam System to Bow in ’04 Lincolns

DETROIT – Gentex Corp. says its new SmartBeam intelligent high-beam headlamp control system will make its debut on an ’04 model Lincoln.

The Zeeland, MI-based supplier of electrochromic mirrors won’t specify the model, but the new device is likely to bow first on the Town Car, followed by the LS.

The system uses a forward-facing CMOS (complementary metal oxide semiconductor) image sensor developed by Photobit Corp. (owned 10% by Gentex) to detect light images on the road ahead and automatically activate or deactivate the vehicle’s high beams. The CMOS camera on the chip, which fits on the tip of a finger, is mounted to the back of the vehicle’s electrochromic rear view mirror and views the road through the windshield.

Joseph S. Stam, Gentex electronics research engineer, says key challenges to developing the system included making sure it detects both oncoming headlamps and leading taillamps, while ignoring light from other sources such as street lamps.

Taillamp light is about 1,000 times less intense than that of headlamps, Mr. Stam says, making it difficult for the camera to see. So Gentex incorporates dual lenses – one clear and one red – to detect incoming red light in order to signal the system to dim the high beams when approaching a vehicle from behind.

To factor out light from street lamps, the camera takes eight images at 480 frames per second to detect the ripple effect that occurs in light patterns from AC powered lamps. Mr. Stam says 99% of all street lamps are fed by AC (alternating current) power sources, while vehicles use DC (direct current) electrical systems.

Gentex isn’t the first to develop automatic high beams, but earlier systems used by Cadillac and Lincoln weren’t able to distinguish from among various incoming light sources and they weren’t very effective at detecting taillamps, Mr. Stam says. They also were set up to switch abruptly from high to low beams, causing a ping-ponging effect under some driving conditions that drivers found disturbing. The Gentex system gradually transitions from high to low beams unless an abrupt change is needed – such as a more sudden appearance of an oncoming car.

The CMOS chip is robust enough to withstand strong exposure to the sun, Mr. Stam says. And the mirror mounting allows the device to connect to the vehicle’s electrical wiring bus to operate the headlamp switches and control module.

In a demonstration video shown here at the Society of Automotive Engineers conference, the Gentex system appeared to operate smoothly in all types of driving situations. The system is set up to turn the high beams off within 500 meters (1,640 ft.) of an on-coming car, which Mr. Stam says studies show is how most people use their high beams. In testing with consumers, "there’s some variability in what distance people want it to dim at," says Mr. Stam. "(But) we set it up in a way that most people would be comfortable."

In part because of U.S. regulations, SmartBeam will come with a switch to allow drivers to deactivate the system.

Gentex says more active use of high beams could help save lives. Some 2,000 pedestrians die annually in accidents resulting from poor visibility, and pedestrians are four to six times more vulnerable at night, Mr. Stam says, citing independent studies. Government research also shows that high beams are used only 25% of time during which conditions warrant.

"This device has the power to save lives," Mr. Stam says.