Andreas Wolf, head of Continental’s Body and Security business unit, explained: “The selective, incremental darkening of the side and rear windows, as well as parts of the windshield, not only offers considerably increased comfort for passengers, but also makes driving safer.”
A typical example is a low sun on the horizon: The driver's hand instinctively goes from the steering wheel to the sun visor decreasing the driver’s control of the vehicle. In the future, Wolf says such situations can be detected in advance, and the windows could darken automatically before the event even occurs.
By using these films, solar radiation can be reduced more effectively than with other technologies. Reflecting heat away from the vehicle will reduce the interior temperature, meaning the air conditioning unit can be smaller, more energy efficient, and therefore lighter in weight. Furthermore, the added weight of the sun visors and mechanical blinds is removed. “Our calculations have shown that the CO2 emissions are reduced by a good four grams per kilometre thanks to these measures, thus increasing the range of electric vehicles by around 5.5%," said Wolf.
Films in which embedded particles can be aligned when a voltage is applied, and which can be used for targeted darkening of the window, have been available for a long time. Until recently, this technology has only been feasible in the roof area for a small number of high-end cars. Engineers at Continental are implementing the intelligent activation of the ‘Suspended Particle Device’ film technology for side and rear windows and the windscreen for the first time in a test vehicle.
This production-ready film technology is based on embedded particles, which arrange themselves randomly when unpowered and darken the window from outside, while retaining transparency from the inside to the outside. If a voltage is applied, the particles systematically align themselves in parallel, so that the window becomes permeable to light in both directions.
The connection to the vehicle system enables the windows to lighten automatically when you approach the vehicle with a key or smartphone. Another safety feature is that the windows could be set to darken when the car is parked, so that the interior of the car cannot be seen from the outside.
