Auto-Dimming Mirrors

Basic Description

Auto-dimming mirrors, also called self-dimming mirrors, can automatically dim and clear according to the ambient and incident light levels. Research shows that headlight glare from cars traveling behind you reflected by your rear view mirror can temporarily blind you while driving at night. This glare can also cause a phenomenon known as the 'Troxler Effect', which slows a driver's reactions and increases the time required for a driver to stop the car in emergency situations.

Auto-dimming mirrors usually have an ambient light sensor and a rear-facing glare sensor. They employ an electrochromic material held between two pieces of glass to dim the mirror. When the ambient light sensor detects a low ambient, it enables the glare sensor. The glare sensor provides a voltage to the electrochromic material proportional to the amount of glare detected. The electrochromic material dims or clears the mirror in proportion to the voltage applied. Thus glare reflected by the mirror won't blind the driver.

Sensors

Ambient light sensor, glare sensor

Actuators

Electrochromic material

Data Communications

Usually none

Manufacturers

CIPA, Exon Science, Gentex, Magna Donnelly, Murakami, Tokai Rika

For More Information

[1] Troxler's fading, Wikipedia.

[2] Electrochromism, Wikipedia.

[3] How Smart Windows Work, Kevin Bonsor, HowStuffWorks.com, Mar. 29, 2001.