Until now, electrochromic glass panels have barely penetrated the automotive industry.
Sliding a window shade up and down in an airplane or the back seat of your Uber Black is so last decade. These days, a button press can electronically darken either of those apertures almost completely, no moving shade necessary. Global automotive supplier Gentex supplies the electrochromic windows for the mighty Boeing 787 Dreamliner, and the fancy glass is now showing up on 777s and some Airbus planes. While the basic technology has been used for years to electrically dim rear-view mirrors and even appeared in limited form in Mercedes-Benz sunroofs, the Gentex display at the 2020 CES included several new automotive glass applications of the technology. Here are a few ways this magic tech could infiltrate new cars in the coming years:
This application faces the fewest hurdles, and hence may be the first to really take off in the market because there are no regulations for light transmissibility of sunroofs. Besides, Mercedes has offered electrochromic, dimmable glass roof panels for many years now (supplied by a different company and marketed under the epic name "Magic Sky Control"). We think it's high time other manufacturers catch on—with Gentex's help, of course. We especially hope Tesla's troops were checking out the Gentex booth, because a fixed electrochromic sunroof would A) make all or mostly glass-top Teslas (such as the Model 3 and Model X) way more comfortable and B) would sidestep the challenge of supplying voltage to a moving sunroof panel. That will leave only the manufacturing challenge surrounding electrochromic layers not being fussy when bent. Most automotive glass fitments aren't flat (airplane windows are), meaning these electrochromic layers must be manufactured very precisely in order to marry them to curved glass panels. This probably explains why such panels have only shown up in Benzes.
Variable Visor Band
Regulations allow for the tops of windshields to be darker than the rest of the glass, so a variable-tint visor band—like electrochromic, variable-tint sunroofs—similarly faces no serious legal hurdles. That said, it's yet to be done. The challenge here is developing an invisible border of the electrochromic and clear main windshield areas.
Self-Darkening Side Glass
Regulations around other automotive glass, namely for side and rear windows, are more restrictive. Plus, different states allow different levels of tint than others, and how they'd treat variable light transmissibility is a mystery. All of which brings us to a key challenge facing Gentex engineers: Increasing the light transmissibility of electrochromic layers. These days, even in the "off" setting, these panels transmit just 55 percent of incident light—well shy of the National Highway Traffic Safety Administration's 70-percent minimum requirement. Full dark transmits just 0.5 percent if you were wondering, and they can be dimmed variably between those points. Another technical upgrade Gentex is working on? The ability to default to a state other than clear (today's power-off default), so that users could opt for side-window privacy when parked.
Head-up displays that don't use the windshield but use a pop-up or stationary "combiner" (i.e., a reflective panel mounted short of the actual windshield glass) can be difficult to read when low-angle sunlight or other bright light sources hit them from behind. Dimming such a combiner, say, with an electrochromic panel, can solve this problem without transgressing transmissibility issues.
Bonus Gentex Fun Fact/Not Glass-Related
Gentex as a company got its start making smoke detectors, and one of its tech displays at CES played to this legacy strength: A smoke detector that could be embedded in a car's HVAC duct and pick up trace whiffs of tobacco smoke or vaping products and alert a shared-ride car owner or rental-fleet operator if a user has transgressed the no-smoking rules. This could make life difficult for future used-car sellers, who'd have trouble arguing against electronic proof that a car had never been smoked in . . .
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