US 7,999,787 · Granted 2011-08-16
How E Ink Invented the Electrically Controlled Ink Behind Modern E-Readers
Imagine ink made of tiny charged particles suspended in a clear liquid. By flipping an electric switch, you can make those particles move around and rearrange themselves to display text or images—and they stay put without needing constant power. That's the core trick behind e-paper screens.
The plain-English version
What it protects
What's protected here is a method for controlling tiny particles in a fluid using electric fields to make them cluster or disperse across a viewing surface. The claim covers the specific use of dielectrophoretic forces—a physics technique where uncharged particles move when exposed to non-uniform electric fields—to drive those particles into different positions on a display substrate, creating visual patterns that can be switched on and off electronically.
Why it matters
This patent is foundational to E Ink's business, which has spent decades perfecting electrophoretic display technology for e-readers, digital signage, and smart labels. By controlling particle movement with electric fields rather than relying on liquid crystals or LEDs, E Ink created displays that consume almost no power once an image is set and can be read in sunlight like printed paper. That fundamental advantage has made the company the dominant supplier of screens for devices like Amazon Kindles.
Real-world use
Every time you turn a page on an e-reader like a Kindle or flip through a digital price tag in a grocery store, you're watching dielectrophoretic particles rearrange themselves behind that crisp, paper-like display.
Original USPTO abstract
A dielectrophoretic display has a substrate having walls defining a cavity, the cavity having a viewing surface and a side wall inclined to the viewing surface. A fluid is contained within the cavity; and a plurality of particles are present in the fluid. There is applied to the substrate an electric field effective to cause dielectrophoretic movement of the particles so that the particles occupy only a minor proportion of the viewing surface.
Patent details
- Publication number
- US 7,999,787
- Filing date
- 2005-08-31
- Grant date
- 2011-08-16
- Assignee
- E Ink Corporation
- Inventor(s)
- AMUNDSON KARL R., ARANGO ALEXI C., JACOBSON JOSEPH M., WHITESIDES THOMAS H., MCCREARY MICHAEL D., PAOLINI, JR. RICHARD J.
- CPC class
- G02F1/167
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