The principle of LC car glass panes works on the basis of floating liquid crystals. With the aid of alternating voltage, the panes can be completely or partially darkened. It is also possible to use the panes as a display.
The principle of LC car glass panes works on the basis of floating liquid crystals. With the aid of alternating voltage, the panes can be completely or partially darkened. It is also possible to use the panes as a display.
( Source: Continental)

Technology These car windows darken and work as touch screens

Author / Editor: Hendrik Härter / Jochen Schwab

Continental is working on the development of a special film technology with which the window can be turned into a display. According to Continental, these car windows will darken automatically or serve as touch-screen displays. The car window becomes a digital interface with a range of features.

These days, the average modern car has about five square meters of glass built into it. That’s almost twice as much as 30 years ago. But while a lot of components already function as high-tech, digitally networked elements, from interior mirrors equipped with a drowsiness detection system to 3D speedometers, car windows are large surfaces that generally don’t serve any digital purpose.

Developers at Continental want to change that. The basis for their innovations is special film technologies, which enable panoramic roofs to darken, part of the windscreen to become tinted when the sun gets low in the sky, or the windows behind the B pillar to darken. If the window pane does not have any kind of integrated heating system, it can be heated by the film. And best of all, the windows fitted with the films can work as displays. Continental calls it Intelligent Glass Control. The concept is to be further developed so that window panes can serve as the car’s user interface.

Floating liquid crystals in car windows

Intelligent Glass Control uses special films, which are integrated into the glass and can change their level of transparency through electric control signals. There is a range of techniques that could achieve this effect, but they all come with different benefits and drawbacks with regard to the window’s optical quality or how quickly it can darken. Before now, windows like this were used primarily for panoramic roofs. Continental is focusing on developing technology that will work in every window in the car and continue to significantly boost the potential of glass control: LC or liquid crystal technology.

One form of LC car windows involves the liquid crystals floating, together with tiny color particles, in a special suspension, which in turn is integrated within a fine film between two thin glass panes. A low AC voltage causes the liquid crystals to align with the color particles in such a way that the window darkens or brightens. With this technology, a transparent window should be able to darken within milliseconds. Crucially, the windows don’t show any visible trace of opacity in transparent mode. It will also be possible to offer this technology in a range of color schemes.

Tinted windows and interior climate control

The general benefit of switchable glazing technologies is that each window in the car can be darkened individually. Legal regulations do not yet permit this technology to be used in all car windows, but there is a whole host of potential future application scenarios. Darkening the rear windows, perhaps for a bit of privacy in the backseat, will also noticeably improve the car’s interior climate. The sun’s thermal radiation stays outside, meaning the car won’t need to be cooled so much in summertime.

If the tinting function in the windscreen is coupled with the car’s electrical system and a connection to the cloud, individual areas of the glass will be able to darken automatically as the weather and position of the sun change. The heat management system also has a string of related benefits: another potential use scenario is the windows, connected to the locking system, being able to defrost instantly in winter when the driver approaches their car.

Touch-screen windows

This technology can also make cars’ adaptive camera systems more effective. These camera systems are very important, for instance for the functions of autonomous driving, and if they are positioned around the rear-view mirror, are impaired when the sun is low in the sky. With Intelligent Glass Control, car windows will be able to take on more functions of human-machine interaction in future: smart glass windows could display information from the driver assistance and infotainment systems. The window could also be fitted with a touch function and become a smart display.

The continued development of Intelligent Glass Control is in line with the general trend, evident in the auto industry, toward increasingly large glass surfaces. And there’s probably no other artificially produced material with as long and successful a history as glass – or with as much potential for the future. What began 2,500 years ago with a Pharaoh’s glass goblet in ancient Egypt has now become an essential field of research and development focusing on a high-tech, hybrid material.

This article was first published in German by