US 5,384,653 · Granted 1995-01-24
The Self-Powered Smart Window That Dims Itself With Sunlight
Imagine a window that gets darker or lighter on its own, powered by tiny solar cells hidden along its edge. When sunlight hits those solar cells, they generate just enough electricity to change the window's tint — no wall outlet needed. It's like having sunglasses that automatically adjust themselves.
The plain-English version
What it protects
The claim covers a double-pane window with an electrochromic (light-sensitive color-changing) coating on one pane, paired with photovoltaic cells positioned along the window's edge to generate power for the tinting effect. What's protected here is the specific combination of these three components working together: the variable-tint material, the solar cells that power it, and a battery that lets you manually override the automatic tinting whenever you want.
Why it matters
This patent bridges two major technology trends of the 1990s: smart glass and renewable energy integration. By embedding solar power generation directly into the window frame itself, it eliminated the need for external wiring or building infrastructure changes — a significant engineering advance for retrofitting existing homes. The manual override battery also solved a real user-experience problem: people want control over their windows, not just automation.
Real-world use
When afternoon sun floods through your bedroom window, the solar cells along the frame wake up and darken the glass automatically, keeping your room cooler without you lifting a finger.
Original USPTO abstract
A variable transmittance double pane window includes an electrochromic material that has been deposited on one pane of the window in conjunction with an array of photovoltaic cells deposited along an edge of the pane to produce the required electric power necessary to vary the effective transmittance of the window. A battery is placed in a parallel fashion to the array of photovoltaic cells to allow the user the ability to manually override the system when a desired transmittance is desired.
Patent details
- Publication number
- US 5,384,653
- Filing date
- 1992-11-06
- Grant date
- 1995-01-24
- Assignee
- Midwest Research Institute
- Inventor(s)
- BENSON; DAVID K., CRANDALL; RICHARD S., DEB; SATYENDRA K., STONE; JACK L.
- CPC class
- E06B3/6722
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