Electronic paper (or e-paper) is a collective name for display technologies that resembles real paper - in terms of display clarity (contrast), sunlight readability, thickness and flexibility. The most popular e-readers (such as Amazon's Kindle) use E Ink display for example.
- Low power: An e-paper display actually uses no power when the image is not changing (it doesn't need to 'refresh' itself).
- High contrast, easy on the eye, no backlight, visible under direct light (sunlight)
While it's possible to fabricate flexible e-paper displays, such displays aren't available on the market today as companies are still perfecting the technology and developing ways to actually commercialize it.
The term e-paper is quite confusing, as actually there are several different technologies trying to achieve the same goal: a flexible, thin, sunlight-readable efficient paper-like display. Here is a list of the leading technologies around:
- E Ink: E Ink (made by E Ink Inc) is the 'original' e-paper technology, and the current market leader. E Ink offers black and white e-paper (color is coming soon) and is used in most e-readers today (Amazon, Sony, Barnes & Noble and others). E Ink displays are also used in other products.
- Sipix: Black and white e-paper made by AUO, quite similar to E Ink. It is currently being produced and used by some e-readers.
- Liquavista: Liquavista develops Electrowetting color displays (when a voltage is used to modify the wetting properties of a solid material) which are very efficient and can operate in transmissive, reflective or transflective modes. Liquavista were acquired by Samsung in 2011 and is working towards commercialization of their displays.
There are also some other technologies, which offers low-power reflective displays. While these aren't really e-paper technologies, they do compete with e-paper displays for sunlight readability and power consumption:
- Mirasol: Qualcomm's Mirasol displays are MEMS based reflective color displays. Mirasol displays offer fast response time and are power efficient (although they do require power even when the image does not change). Small Mirasol displays are currently being produced and Qualcomm is working towards a larger fab that will produce displays suited for e-readers (5.7" and larger).
- Pixel Qi: Pixel-Qi offers hybrid LCD/e-paper technology: you have one display that can can be switched between a full-color normal LCD and a black-and-white low power reflective display. Pixel-Qi displays can provide a great solution for laptops and tablet and are starting to appear in tablet computers today.
E Ink is currently the clear leader in e-paper displays. E Ink screens are made by E Ink Inc and are used by Amazon, Sony, Samsung, Barnes & Noble and others in their e-readers and other products.
E Ink displays are Electrophoretic (a science which was actually discovered back in 1807 and deals with particle motion as influenced by electric field): they are made of tiny capsules (0.04mm in diameter) that contain two kinds of particles: black and white. Using electricity you can choose whether the white or black particles will rise to the top of the capsule - and so change the color of the pixel. Those particles remain in place when no electricity is used - and so the displays do not need power when the image does not change. E Ink also offers color e-paper which uses color filters on top of the black and white display (these aren't available commercially yet).
Where can I find e-paper displays?
The most popular application for e-paper displays today is an e-reader. Popular readers include Amazon's Kindle, Sony Readers and the Barnes & Noble Nook. Those e-readers feature great sunlight readability and long battery life (a few weeks usually) - all thanks to the E Ink display.
Other products include mobile phones (for example the Motorola Motofone which uses an E Ink as the main display and Samsung's Zeal which uses small E Ink displays on the keyboard), wrist watches, hard-disks and more.