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How does an e-ink display work?

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Quick answer

An e-ink display uses microscopic capsules filled with clear fluid and charged black and white pigment particles. An electric field pulls one colour to the top of each capsule, forming the visible image. Because the particles stay in place after the voltage is removed, the display holds its image without using power until the next refresh.

An e-ink display works by moving tiny black and white pigment particles through a clear fluid inside microscopic capsules using electric fields. The particles stay where they are pushed, so the image remains visible without power until the next page change.

Step by step

  1. Each pixel is made of a tiny microcapsule containing clear fluid and two types of pigment particles.
  2. White particles are positively charged, and black particles are negatively charged.
  3. A transparent electrode layer above and a back electrode below apply voltage across the capsule.
  4. The electric field pulls the black particles to the top for a dark pixel or the white particles for a light pixel.
  5. When the voltage is removed, the particles remain stuck to the capsule wall, holding the image.
  6. A new voltage pattern rearranges the particles to show the next page or image.

Key things to understand

  1. Each pixel contains a microcapsule filled with clear fluid and two types of charged pigment particles.
  2. In the standard design, white particles carry a positive charge and black particles a negative charge.
  3. A transparent electrode grid sits above the capsules, and a back electrode sits below.
  4. Applying voltage between electrodes creates an electric field that pulls one colour to the top.
  5. The particles stick to the capsule wall after the voltage is removed, holding the image without power.

Labelled diagram

  1. Top electrode

    Transparent conductive layer that applies voltage above the capsule.

  2. Microcapsule

    Tiny sphere filled with clear fluid and charged black and white particles.

  3. Black particles

    Carry negative charge; rise to the top when the top electrode is positive.

  4. White particles

    Carry positive charge; rise to the top when the top electrode is negative.

  5. Bottom electrode

    Back conductive layer that completes the electric circuit for each pixel.

How an e-ink pixel works

Real-world examples

  • Amazon Kindle e-readers use e-ink to show books for weeks on a single charge.
  • The Kobo Libra 2 e-reader uses a 7-inch e-ink screen for reading in bright sunlight.
  • Electronic shelf labels in supermarkets use e-ink to display prices that update wirelessly.
  • Some smartwatches and fitness bands use e-paper displays for always-on screens with low power draw.

Common mistake

✗ Myth: E-ink displays use no power at all.

✓ Fact: E-ink displays use no power to maintain an image, but they do draw power when the image changes. Each refresh requires a voltage pulse to move the pigment particles, so frequent page turns still drain the battery.

People also ask

What is e-ink made of?
E-ink is made of millions of microcapsules, each about the width of a human hair. Inside each capsule is a clear fluid with black and white pigment particles that carry opposite electric charges. The capsules are sandwiched between transparent electrode layers that control the particle movement.
Why does e-ink look like paper?
E-ink looks like paper because it reflects ambient light instead of emitting light like an LCD. The white particles scatter light back to your eyes, just as paper does. This makes it readable in bright sunlight and easier on the eyes for long reading sessions.
How long does an e-ink display last?
An e-ink display can last for many years because it has no backlight to burn out and few moving parts. The main wear comes from the electrode layers and the fluid slowly degrading. Most e-readers remain usable for five to ten years with normal use.
Why does an e-ink screen only show black and white?
Standard e-ink uses two pigment colours, black and white, because the electric field can only pull one type of particle to the surface at a time. Adding more colours requires extra particles or colour filters, which reduce contrast and speed. Colour e-ink exists but is slower and less vivid.
Why is e-ink so slow to refresh?
The pigment particles must physically travel through the fluid inside each capsule, which takes tens to hundreds of milliseconds. That is far slower than flipping liquid crystals in an LCD. The trade-off is that the image stays put without power, unlike an LCD.
Does an e-ink display use power when the page is not changing?
No. Once the particles are positioned, they remain stuck to the capsule wall by van der Waals forces and do not need electricity to stay visible. Power is only drawn during a page refresh. This is why e-readers can last weeks on a single charge.
Can e-ink displays show video?
Not smoothly. The particles need time to move, so refresh rates are typically under 10 frames per second, far below the 24 frames per second needed for video. Some advanced e-ink panels reach higher rates but still look flickery and are not used for video playback.

Part of the guide: How the Internet Works →