Anyone who has driven down a dark street and found it difficult to see, even with the car’s headlights on, can take heart.
Over the next several years, a new type of automotive lighting will become common, one that promises to light up the roads of America like never before. It’s called high-intensity discharge, or HID, lighting.
An HID lamp will produce up to 2 1/2 times more light than today’s low-beam headlamps, use less electricity and last 10 times as long. HID is the centerpiece of several new lighting innovations that manufacturers such as BMW, Ford Motor Co. and General Motors Corp. will introduce this decade to meet an expected demand from an aging, less visually acute population for improved and more extensive lighting sources.
In terms of automotive lighting, America has historically been in the dark ages-mainly because of federal standards. For decades, tungsten sealed-beam headlamps were the only legal car lighting.
The lamp-with filament, reflector and lens permanently sealed-came in round, two- or four-lamp versions. By the late 1970s, the now standard rectangular units also could be fitted. In the mid-1980s the government deregulated the lamps’ shape. So, today’s car headlamps look more modern than those that graced the boxy Chevrolet Impalas and Ford Fairmonts of 15 years ago, but they perform no better.
At the same time, European and Japanese manufacturers were selling cars in their home markets with brighter, multisize headlamps designed to go with the styling and dimensions of the vehicle. Despite the brightness, a sharply defined beam pattern reduced glare to oncoming drivers. Yet, when those cars were shipped to America, the lights were replaced by standard low-output tungsten units.
“U.S. headlamp specifications came about when lighting manufacturers took samples to empty airfields, shone them down the runway and then voted for which looked the best,” said Barry Felrice, the associate administrator of rule making for the National Highway Traffic Safety Administration. “There’s been no scientific study to determine the ideal pattern of light that a car headlamp should throw.”
“Lighting standards have a lot of room for improvement,” said Tom Troy, BMW’s product training manager in this country. “Ideal headlights would be brighter and shine more light to the sides of the road to improve peripheral vision.”
Yet, faced with an increasing need to improve vehicles’ aerodynamics to increase fuel economy and pressure from car designers to integrate lights better into the shape of the car, domestic manufacturers have concentrated on changing the shape of the headlight, not its capabilities.
In the mid-1980s, Ford’s Lincoln Division became the first Detroit distributor to offer cars that used non-sealed-beam lamps that sat flush with the body panels, allowing air to flow over rather than into the lamp. But most headlights are still of the old-fashioned variety and do not transmit as much light as the government standards allow.
“We’re allowed by regulation to produce headlights that deliver 20,000 candelas on low and 75,000 on high beam,” said Walter Kosmatka, a General Electric Co. lighting engineer, “but regular tungsten sealed beams put out only 8,000 to 10,000; with halogen, the output rises to 12,000 on low,” or 60 percent of maximum. (Halogen light is whiter than tungsten, so drivers often perceive it to be brighter.) High beams perform somewhat better; two lamps typically produce 50,000 candelas per side, and a four-lamp setup delivers 70,000, close to the legal limit.
High-intensity discharge lighting, on the other hand, delivers the permissible 20,000 candelas of brightness on low; it consumes 40 percent less electric current and generates a correspondingly smaller amount of heat. So, HID headlamp units can be made narrower and thinner, increasing space in the engine compartment and allowing smoother sculpting of the front of the vehicle.
HID lighting has been used for years in sports arenas. For cars, engineers had to reduce the bulb size and dramatically speed the time it took the unit to illuminate, to a split second from several minutes.
Here’s how HID car lighting works: A quartz glass capsule filled with inert xenon gas receives a momentary high-intensity 10,000-volt charge from an electronic ballast in the unit, causing an arc to light between two electrodes. Once lit, the charge drops to a constant 85 volts. To protect drivers and mechanics from electrical hazards, opening the headlamp unit or ballast deactivates the system.
The extremely bright light produces a white beam, mimicking the sun’s rays in color. Additionally, ultraviolet light emitted by the bulb helps illuminate reflectors in road signs and any neon coloring in pedestrians’ clothing. Coupled with a projection-type lens that focuses the beam and reduces glare to oncoming vehicles, the light dramatically increases illumination to the side and directly in front of the vehicle.
“These lights are demonstrably brighter, and they’ll last 10,000 hours, rather than the 1,000 typical of a halogen lamp. That’s the life of the vehicle,” said Gil Davenport, project manager at Buick’s advanced concept group. “When I drive friends around-who know nothing about cars-in my special HID-lit Buick, they all want to know why my headlights are so good.”
BMW is the only manufacturer to offer HID lamps at present. It charges a $900 premium for the system in Europe, but includes it in the $80,900 list price of its 1993 model 750 in the U.S.
Ford will introduce HID lamps as an extra-cost option in the next few years. “Once we get the price down to $50 per vehicle, it will really take off,” said Larry Kazanowski, Ford’s director of vehicle exterior systems, for the plastic and trim products division.
Davenport’s group at GM has asked the company to include HID lighting in its 1997 Buick Park Avenue and Oldsmobile 98, “but now I think our HID program will be extremely accelerated,” he said.
The major Japanese manufacturers, Honda, Nissan and Toyota, said they were investigating HID systems but would not comment on whether or when they would introduce them.
HID lights are so intense that, in the foreseeable future, they could become one of just two sources of a vehicle’s lighting. In a concept called a “light engine” developed and promoted by GE, fiber optics, with high-intensity lighting, would be used to reduce dramatically the number of replaceable bulbs in a vehicle. A car with a light engine would have about 10 bulbs, in contrast to the 80 now used.
Fiber-optic cable would feed light to wherever it was needed; headlamps and stop and turn signals could be powered by HID lamps, and halogen or light-emitting diode (LED) bulbs would do the same for interior instruments. With only a thin fiber cable transmitting light to the front of a vehicle, the area devoted to the car’s lighting system can become even smaller, presenting less of a challenge to designers.
Perhaps more important to drivers, lighting door handles and floor areas, for example, which has been impractical and expensive, would be feasible with fiber-optic cable. That should prove a boon to the growing number of Americans making the transition from John Lennon-style glasses to bifocals.
