US 5,668,663 · Granted 1997-09-16
The Electrochromic Mirror That Dims Itself at Night
Imagine a car mirror that automatically gets darker when headlights from a car behind you shine into it—no manual adjustment needed. This patent covers the chemistry and construction of smart mirrors that use electricity to change how much light they reflect, protecting your eyes from blinding glare while driving.
The plain-English version
What it protects
The claim covers a mirror whose reflective properties shift electronically through electrochromic reactions. What's protected here is the specific combination of a solid electrochromic film paired with an electrolyte that contains redox reaction promoters and alkali ions or protons. Anyone manufacturing or selling an auto-dimming mirror using this electrochemical approach would need a license from Donnelly to avoid infringement.
Why it matters
This patent represents a key innovation in automotive safety and comfort. Rather than relying on mechanical shutters or photosensitive glass, electrochromic mirrors offer instant, electronically controlled dimming with no moving parts—making them more reliable and responsive. Donnelly's control of this technology gave them significant leverage in the automotive supply market during the 1990s and 2000s.
Real-world use
Every time you drive at night with oncoming traffic behind you and the rearview mirror automatically darkens to reduce glare, you're benefiting from electrochromic mirror technology covered by patents like this one.
Original USPTO abstract
The present invention relates to electrochromic mirrors and devices whose electrochromic element is composed of an electrochromic solid film and an electrolyte comprising redox reaction promoters and alkali ions and/or protons.
Patent details
- Publication number
- US 5,668,663
- Filing date
- 1994-05-05
- Grant date
- 1997-09-16
- Assignee
- Donnelly Corporation
- Inventor(s)
- VARAPRASAD; DESARAJU V., HABIBI; HAMID, MCCABE; IAN A., LYNAM; NIALL R.
- CPC class
- B60R1/088
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