Continental shows off Intelligent Glass Control with automatic electronic shading
At the Consumer Electronics Show (CES) in Las Vegas in January, automotive supplier Continental showed off a demo vehicle that had a shady disposition: All of its windows darken at the touch of a button. "Intelligent Glass Control" uses special films that are inserted into the glass and change their transparency through electric control signals.
Controllable incremental darkening of car windows prevents heat entry and light blinding -- and can ultimately lower CO2 emissions.
"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," said Andreas Wolf, head of Continental's Body & Security business unit.
A typical example is a low sun on the horizon. The driver's hand instinctively goes from the steering wheel to the sun visor, which "results in both impaired visibility and a brief decrease in control of the vehicle," said Wolf. In the future, such situations can be detected in advance, and the windows could darken automatically before the event occurs.
Wolf said that solar radiation can be reduced more effectively for applications in the total vehicle glass surround by using the film technology than with other methods. "This [also] means that we can keep the heat out of the vehicle and significantly reduce the interior temperature," he said. This relieves the air conditioning unit, which could be made smaller and more energy efficient -- and therefore much lighter in weight. Furthermore, the added weight of the sun visors and mechanical blinds is removed, with positive effects on the environment. "Our calculations have shown that the CO2 emissions are reduced by a good four grams per kilometer thanks to these measures, thus increasing the range of electric vehicles by around 5.5 percent," said Wolf.
In addition to the reduced heat in the interior, window darkening also effectively enhances privacy. "If the vehicle is parked, the windows darken automatically, so the inside of the vehicle cannot be seen from the outside," said Wolf.
Intelligent Glass Control also gives designers new options. According to Wolf, the glass surfaces could be extended further, without having to cover certain areas mechanically.
One technical drawback is that the available film still has a slightly blue shimmer, but in the future Continental is expecting a broader range of colors, opening up additional design possibilities. Other effects, from coupling light effects through energy recovery to touchscreen functionalities, may also be possible.
Getting particles to align under current
Films that feature embedded particles that can be aligned when a voltage is applied -- and that can be used for targeted darkening of windows -- have been available for a long time. But up to now, this technology has only been feasible in the roof area for a small number of high-end cars. Engineers at Continental demonstrated the intelligent activation of the "Suspended Particle Device" film technology also for side and rear windows and the windshield for the first time in a test vehicle. (Due to legal requirements, however, the technology was only shown in the permitted area of the sun visors for the windshield.)
The production-ready film technology is based on embedded particles that 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.
This film is still rather cost-intensive for mid-range vehicles with large glazed areas. However, due to further promising developments with initial applications in the mobile-tech area, it is anticipated that the prices could drop quickly. Other alternatives to the film technology are based on liquid crystal polymers or electrochromism. The latter uses the ability of molecules and crystals to change their optical properties under the influence of an electric field or a current flow. This technology is already deployed in cars in order to darken the interior and exterior mirror to prevent glare effects. The disadvantage of this tech use on larger surfaces is the high energy requirement needed to achieve short switching times.
But regardless of which method is used for automatic shading, Wolf said that it is the software and the intelligent connection to the vehicle system that ultimately drive the complete system technology. It's not a question of if intelligent glass is coming, he said, it's when.
"At Continental, we use our know-how for the entire system and can therefore integrate the desired functions into our electronic control units," Wolf said. "Here we adjust the algorithms so that the behavior of the windows offers maximum safety and comfort for the driver while improving emission values. The appearance of all windows is optimized with an intelligent reaction to the changing lighting situations as well as automatic compensation of temperature and aging effects."
Published January 2016
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