US 6,055,089 · Granted 2000-04-25
The Smart Window That Powers Itself With Sunlight
Imagine a window pane that can automatically darken or lighten itself without any wires or batteries — powered entirely by the sun hitting the glass. This patent describes exactly that: a special glass unit with color-changing material inside that solar cells power, plus a wireless remote to control it from outside.
The plain-English version
What it protects
The claim covers a sealed glass window unit containing an electrochromic layer (material that changes color when electricity flows through it), powered by built-in photovoltaic cells, and controlled wirelessly from outside the window via remote signals that penetrate the glass magnetically. What's protected here is the specific combination of self-powered color-changing glass, the positioning of solar cells so light can pass through them and the electrochromic layer simultaneously, and the use of variable resistance circuits to fine-tune how the window responds to changes in sunlight.
Why it matters
This patent addresses a real engineering challenge: how do you make a window that adapts to sunlight without running wires through the walls or replacing dead batteries every few months? By having the window power itself through the very sunlight it's filtering, the design creates a self-sustaining smart window. The wireless control mechanism (using magnetic signals) eliminates the need for embedded electrical connections, which would weaken the seal. This opens the door to energy-efficient buildings that can automatically manage heat and glare without external power sources.
Real-world use
In a sunny office building, the window could automatically darken during the hottest part of the day to keep the room cool and reduce air conditioning load, all powered by the sun itself — no plug required.
Original USPTO abstract
A sealed insulated glass unit is provided with an electrochromic device for modulating light passing through the unit. The electrochromic device is controlled from outside the unit by a remote control electrically unconnected to the device. Circuitry within the unit may be magnetically controlled from outside. The electrochromic device is powered by a photovoltaic cells. The photovoltaic cells may be positioned so that at least a part of the light incident on the cell passes through the electrochromic device, providing a form of feedback control. A variable resistance placed in parallel with the electrochromic element is used to control the response of the electrochromic element to changes in output of the photovoltaic cell.
Patent details
- Publication number
- US 6,055,089
- Filing date
- 1999-02-25
- Grant date
- 2000-04-25
- Assignee
- Minnesota Mining And Manufacturing Company
- Inventor(s)
- SCHULZ; STEPHEN C., MICHALSKI; LECH A., VOLLTRAUER; HERMANN N., VAN DINE; JOHN E.
- CPC class
- G02F1/163
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