General Motors (GM) filed a patent application for a new, electrically heated windshield system last year, according to a patent application that was published earlier this month.
The patent, published on July 13 as US 2023/0225016 A1, describes “an electrically heatable panel” that could feature “conductive coating patterned to have a conductive profile with a narrow region whereby current density is greater in the narrow region, thus providing increased heat dissipation in the narrow region.”
In its application, GM outlines how “windshield moisture” can impede driver visibility as well as departure as a vehicle operator clears the ice, fog, frost or mist from the windshield before driving. Traditional defrost systems, the company points out, rely on hot air blown from a combustion engine that won’t heat until the engine itself reaches a certain temperature, “thereby resulting in heat availability delays,” says the patent filing. “In electric vehicles, the heat source for the warm air may come from a resistive heating element, thereby providing relatively rapid heat availability.”
Either way, GM inventors wrote in the patent, current defrost systems only clear small areas of glass at any given time. Conductive inks can provide electrically resistive defroster grids on a backlite, the patent application acknowledges, but those are not options for windshields as they would also impede a driver’s vision in a different way.
Current electrically heated windshields “include a conductive coating as an interior layer in a laminated windshield” to heat it from the inside, GM explains. However, “current and power available from 12 volt automotive accessory power systems limit the effectiveness and utility of such systems.”
According to the patent, what sets the GM system apart from currently available systems is the area of defrost “may include a respective locally narrow region of the passenger side of the windshield, and a respective locally narrow region on driver side of the windshield.” Those narrow sections are outlined as being “side central” regions of each section, respectively, though the patent further states that in a windshield in this system “the effective conduction region may include a conductive profile with at least one locally narrow region between the first bus bar and the second bus bar.”
Additionally, GM spells out in the patent that manufacturing of the windshield system “may include coating a windshield sheet substrate with a conductive coating to substantially completely cover the windshield, ohmically coupling the conductive coating” between the bus bars “and selectively removing the conductive coating along isolation paths to pattern an effective conduction region …”
Four engineers are listed as inventors on the patent: Julien P. Mourou, from Michigan; Rachit Garg from Bangalore, India; Omar Rodrigo Garcia Martinez of Tlalnepantla, Mexico; and Gerard Parij, also from Michigan.