E-paper

From MobileRead

Electronic paper, also sometimes called e-paper or electronic ink (E-Ink), is a display technology designed to mimic the appearance of regular ink on paper. Formally the name for this is EPD (Electronic Paper Display). The "ink" used with such "paper" is called e-Ink. The technology is from a company called e-ink Corporation.

[edit] The Technology

E-ink is a technology that uses tiny liquid filled bubbles that contain both white and black "ink". Each bubble represents a pixel on the screen display. Electronic charges are applied to the bubble to bring either the white ink or the black ink to the surface. Once the charge is removed the ink will stay at the surface so it can been seen without any power applied. The bubbles are the same size as a pixel on the screen and the connection of all these bubbles can form text characters and images on the surface of the screen. A positive charge will cause white ink to appear while a negative charge will cause black to appear. A charge can applied to effect a small portion of the bubble instead of the whole bubble. This can be used to cause a mix of white and black (gray) to appear.

Initial e-books that used EPD were able to show 4 levels of gray (black to white) but the latest technology has been able to achieve 8 levels of gray. The iRex iLiad has managed to do 16 levels of gray with a custom controller. Additional apparent gray levels can be done using dithering to achieve more levels than what can be done with the controller. Supporting Gray scale can improve the looks of images in the e-books and may (depending on the implementation) even be used to smooth font edges that use diagonal lines or curves (this technique is called anti-aliasing). Note that the performance of the display is better if only 2 colors are used.

EPD has sufficient contrast to be read quite well in direct sunlight. EPD is not transparent so it cannot be backlit, thus it requires external lighting to be read in the dark.

E-paper displays are expected to find applications in signage, on shelving for the display of information, and on packaging for the display of pricing and instructions. These displays are also already used in portable eBook reading devices, in clocks, and in USB sticks.

Currently, there are opportunities in improved color paperlike, fully flexible, low-cost paperlike and self-edge displays, and other labeling applications.

[edit] E-paper Technology Providers

[edit] Limitations

• Current displays are only in greyscale, not color.
• The refresh rate of the screen is very low compared to standard LCD screens : about 1 to 2 seconds, compared to about 30 ms for LCD. Mixing pure text content with Flash or video content is not currently possible. Web browsing using scrolling is not really suitable on E-ink displays
• The refresh of an eInk page creates a black flash and can create temporary "ghosting" effect which can be annoying to some people.
• There is no way to backlight the display as the technology is opaque.

[edit] E Ink Display Specifications

Updated for Vizplex display.

[edit] Optical

In actual practice the grayscale capability is up to the controller hardware and can range from 4 levels to 16 levels in currently shipped devices.

[edit] Mechanical / Dimensional for 6" Display

There are other display sizes available.

9.7" (5.6" x 8.1") 1200 x 825 pixels

8.0" 1024 x 768

5.0" 800 x 600

For more details see: http://www.eink.com/products/matrix/High_Res.html

For display controller specs see: http://www.eink.com/products/matrix/metronome.html

[edit] Environmental

[edit] Electrical

[edit] Notes on earlier E-Ink devices.

The older display technology has 4 level gray scale and slower update times of 1000 ms for gray scale and 500 ms for 1-bit mode. These were primarily 6" devices. They also had less reflectivity. This causes these devices to appear less white (light grey background) and have less contrast.

The iRex iLiad, on the other hand, uses a custom display controller that achieves 16 levels of gray scale. They are also using an 8.1" display featuring a 1024 x 768 pixel display.

See also E-paper and E Ink

[edit] Review of E-Ink

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