US 5,115,346 · Granted 1992-05-19
The Mirror That Won't Shatter, Fade, or Fog
This is a rearview mirror for cars that solves three annoying problems at once: it won't scatter into dangerous fragments if you crash, it stays clear in humid weather, and special tinted glass keeps sunlight from breaking down the mirror's reflective coating over time. It's basically a mirror designed to survive.
The plain-English version
What it protects
The patent covers a rearview mirror assembly that combines multiple protective layers: tempered or safety glass panels bonded together with UV-blocking interlayer material, optional UV-blocking coatings or films, and a specially formulated electro-optic medium (the reflective liquid) that contains yellow/orange/red light-absorbing dyes. What's protected is the specific combination of these materials and how they work together to prevent shattering, block UV rays, and resist fogging in humid conditions.
Why it matters
Donnelly Corporation was a major automotive supplier, and this patent addresses real durability challenges in car mirrors. Rearview mirrors are constantly exposed to sunlight and humidity, which degrade reflective coatings and cause fogging. The patent's innovation was bundling safety (laminated glass that won't shatter into sharp fragments) with longevity (UV protection) and functionality (anti-misting) into one assembly. This kind of integrated approach to material science protected Donnelly's competitive advantage in supplying mirrors to automakers.
Real-world use
Every time a driver adjusts their rearview mirror on a sunny day, they're benefiting from the UV-absorbing materials and anti-fog technology this patent describes—even though they'll never notice it working.
Original USPTO abstract
An electro-optic rearview mirror assembly is disclosed which is protected against scattering fragments while reducing risk of laceration if broken/damaged, against ultraviolet (UV) radiation degradation, and against fogging or misting in high humidity conditions. The mirror may include a first element incorporating specialized yellow/orange/red visible light absorbing, UV radiation reducing glass having a blue or green color to provide a consumer acceptable silvery reflection even when yellow tinted UV radiation absorbing additives are mixed in the electro-optic medium of the assembly. The first element may be laminated from a pair of optically transparent, tinted, tempered safety, or other glass panels and incorporate UV radiation reducing paint/lacquer coatings or polymeric films. The panels may be secured together with UV radiation reducing Saflex TM PVB sheeting, or other UV radiation reducing polymeric interlayers including blue or blue/green tinted, yellow/orange/red visible light absorbing sheeting or UV curable, pourable adhesive. Yellow/orange/red light absorbing dye may be incorporated in the electro-optic medium or the curable adhesive.
Patent details
- Publication number
- US 5,115,346
- Filing date
- 1990-01-16
- Grant date
- 1992-05-19
- Assignee
- Donnelly Corporation
- Inventor(s)
- LYNAM; NIALL R.
- CPC class
- B32B7/12
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