How Automatic Mirrors Came to Exist
Drivers had dealt with headlight glare for decades by flipping a manual tab that changed the mirror angle. The tab worked, but required the driver to notice the glare and take action every time bright lights appeared behind them. Gentex Corporation automated this process in 1982 by connecting light sensors to a small motor that tilted the mirror when glare appeared. These electromechanical mirrors became optional equipment in luxury cars by 1983.
The motor system solved the glare problem, but the mechanical parts made it expensive and prone to failure. Engineers kept searching for more reliable ways to help the public drive safely at night and avoid accidents.
A father and son team of chemists brought Gentex the answer. They had developed an electrochromic gel that darkens when electricity flows through it and clears when the current stops. Gentex spent years refining a way to sandwich a thin gel layer between two pieces of glass. Sensors mounted on the mirror housing could now trigger an electrical charge that darkened the gel instantly, with no moving parts.
The first electrochromic mirror appeared in the 1988 Lincoln Continental. Eight GM models added the feature in 1989, and the technology spread through the industry during the early 1990s. Donnelly Corporation developed similar technology and tried to compete. Gentex sued them for patent violations in 1990, starting a legal battle that lasted through the decade. Both companies survived and kept making mirrors, but Gentex maintained the dominant position.