US 7,338,177 · Granted 2008-03-04
The Smart Rearview Mirror That Shows GPS Without Blocking Your View
Imagine a rearview mirror that's actually two mirrors working together: one acts as a normal mirror so you see behind you, while a second layer lets light from a hidden display screen shine through it. That way you can see both the road behind AND your GPS directions on the same mirror.
The plain-English version
What it protects
The claim covers a rearview mirror assembly where a wedge-shaped prism sits in front, with a reflective layer attached to its back via a special transparent glue. Behind that, a display screen is positioned so that light from the screen passes through the reflective layer and the prism to reach the driver's eyes. What's protected is this specific sandwich of optical layers that lets you see through a mirror while also seeing images displayed behind it.
Why it matters
Before this invention, adding a display to a rearview mirror meant either blocking your view of the road or requiring a separate screen mounted elsewhere in the cabin. This patent solved that problem by making the mirror itself transparent enough to show information while still functioning as an actual mirror. It became the foundation for the heads-up display mirrors that are now standard in luxury vehicles.
Real-world use
When you glance at the rearview mirror in a modern luxury car and see your backup camera feed or navigation arrows overlaid on the reflection, you're looking through the optical layers this patent describes.
Original USPTO abstract
An interior rearview mirror assembly for a vehicle includes a prismatic mirror element and a display element. The prismatic mirror element includes a wedge-shaped prism element having a front surface and a rear surface and a second element having a transflective reflector on a first surface thereof. The front surface of the prism element generally faces a driver of the vehicle when the mirror assembly is installed in the vehicle, and the rear surface is opposite the front surface. The transflective reflector coated first surface of the second element is attached to the rear surface of the prism element via an optically matching medium. The display element is positioned to the rear of the prismatic mirror element and operates to display information through the prismatic mirror element so as to be viewable by a driver of the vehicle when the display element is operated to emit visible light.
Patent details
- Publication number
- US 7,338,177
- Filing date
- 2004-11-19
- Grant date
- 2008-03-04
- Assignee
- Donnelly Corporation
- Inventor(s)
- LYNAM NIALL R.
- CPC class
- B60R1/12
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