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Light up the night

india Updated: Aug 28, 2009 11:25 IST
Grease Monkey
Grease Monkey
Hindustan Times
Highlight Story

Technicalities out of the way first — ‘headlamp’ is the assembly which contains reflectors, lenses and bulbs and emits light to help you on your way in the dark with the help of electricity. Headlight, on the other hand, is the actual light that the headlamp emits. And I thought they were as simple as a torch.

That isn’t entirely untrue, actually. It’s the ‘simple’ bit that’s a little complicated. A torch has a bulb that emits light, a reflector that helps concentrate the light in the direction is pointed, and both these are present in a car or motorcycle’s headlamp as well. However, all the components of the headlamp have to adhere to strict safety guidelines, pertaining to the relevant authority. There are other features in a headlamp that help it perform better — for example, when glass lenses were banned to increase pedestrian safety, all manufacturers switched to plastic, the next best alternative.

However, they found that over the years the plastic lenses dulled or crazed, which made the beam dull as well. Clear plastic lenses were then developed, which you can see on many cars today.

Reflector patterns
If you look carefully at the old lenses (try to do this while the headlamp is off, please) you’ll notice they have a specific pattern to them. It isn’t just for visual appeal, the design helps focus the beam better so that not much of the light from the bulb is wasted. You will also notice patterns in the reflector — these have the same function as the designs in the old plastic lenses.

For countries that drive on the left hand side of the road, the low (or dipped) beam, also called the ‘dipper’, has a much further reach on the left side. This is so that the driver can see pedestrians, road signs and the edge of the road well in time to react. The right side of the beam doesn’t go as far ahead, because if it did, it would blind oncoming drivers. The exact opposite applies to left-hand-drive cars — if you’ve been dazzled by a left-hand-drive car’s headlamps on our streets, now you know why.

Spreading the beam
The dipped beam is designed to light up the road, and give the driver assistance while cornering as well, which is why the beam spread is substantial. The high beam, on the other hand, is designed to throw light in almost a straight line in front of the vehicle. Do try not to use your high beam unless there is absolutely no traffic coming in the opposite direction, you might end up dazzling drivers of cars that you’re following as well. Cars are now being engineered with all kinds of aids to help light up the road at night. The VW Passat’s top-end variant, the DSG S, has got ‘cornering lamps’ which literally emit light from the corners, should you turn the wheel over. The new Skoda Superb uses a simpler solution. If the wheel is turned to one side, the fog lamp on that particular side comes on to light up the road. This works only if the headlamps are on but the fog lamps are off. The new S-Class has got headlamps that detect oncoming traffic, and dip automatically if the car has the high beam switched on!

Next week, we’ll discuss solutions designed by manufacturers to meet lighting and safety requirements for headlamps.

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