Halogen headlights are probably the oldest technology you can get in a new car today. They comprise a glass bowl, filament and gas. When current is passed through the filament is gives off light. Halogen gas is used in the bulb to keep the bulb staying brighter for longer. The gas prevents the tungsten filament blackening the surface of the glass. While they’re cheap and easy to replace if they break – you can do it yourself in most cases – they’re not as energy efficient as LED or xenon lights, which does affect fuel economy. They’re also not efficient in themselves – around 80% of the energy from a halogen bulb is waste heat. And on top of that, halogen bulbs do break from time-to-time, rather than LED technology which is expected to last for the whole lifecycle of a car.
How are car headlights developed today? We find out from Seat:
Headlights might be something every car has, but have you ever thought about how much work has to go into making them? Tony Gallardo, design leader exterior components at Seat said, “At first we didn’t have much to do, but as time developed, the introduction of design in light illumination has become more important.” Today, Seat’s headlights take around three years to design and build! From a design perspective, headlights are a key part of a car’s character, but have to be developed with engineers and designers working closely together. Many car manufacturers now have a ‘light signature’, which is a design you will see running through a company’s entire range. Seat’s ‘light signature’ is a triangle. But that triangle has to evoke different things in different cars. Designers work with engineers from the very start, and there’s plenty of back and forth. There has to be a compromise between cost, and the final product. And quite often, the lights will differ across a car range – a basic car might have halogen lights, whereas LED or Xenon lights are found further up – so all this has to be taken into consideration.
The process of building LED headlights:
Initially, designers and engineers sketch plans for car lights. The next step is to build exterior 3D designs with no LEDs, before moving onto building LED models with all the electronics in place. It’s important to protect the LED chips, and engineers have to factor in both fan cooling and radiators, to deal with the heat coming off them. From here it’s onto CAD (Computer Aided Design), and first renders. To show how the lights will work, without building them first, Seat runs computerised simulations. These show all the necessary information, including light distribution over different distances. In total, Seat runs around 300 simulations. Once everything has passed the simulation stage, engineers build mock-ups of all the lights, which are close to the finished article but not quite there in terms of quality. It’s then on to static and dynamic tests. There are so many factors to consider, including the fact the light beams have to be asymmetric as not to dazzle other drivers.