ElectronicPaper(e-Paper)

Introduction
E-paperalso known as electronic paper or electronic ink display.
Unlike conventionalbacklitflat panel displayswhich emit light:
E-paper displays reflect light like ordinary paper
Theoretically making it more comfortable to read
And giving the surface a wider viewing angle compared to conventional displays.
Extremely light and flexible.

Construction of E-paper
•It has two different parts.
•Front plane.
•Back plane.
•The front plane consist of E-ink.
•The back plane consist of electronic circuits.
•Back plane is made up of organic thin film transistor arrays which provide voltage needed by the E-Paper.
•To form an E-ink electronic display the ink is printed onto a plastic film that is laminated to a layer of circuitry.

•The front plane consist ofE-ink.
•E-ink is made up of millions oftiny microcapsules.
•Microcapsules have diameter of the order of 100 microns.
•Each microcapsule contains positively charged white particles and negatively charged black particles suspended in a clear fluid . Front plane

When a positive or negative electric field is applied, corresponding particles move to the top of the microcapsule where they become visible to the viewer. This makes the surface appear white or black at that spot.

Back Plane Layout

Technologies proposed so far

Gyricon
•It was the first electronic paper and was developed in 1970’s.
•Consists of polyethylene spheres having diameter between 75-106 micrometers.
•Each sphere is ajanus particlecomposed of negatively charged black plastic on one side and positively charged white plastic on the other (each bead is thus adipole).
•These spheres are embedded in transparent silicone made sheet,with each sphere suspended in a bubble of oil so that they can rotate freely.
•The polarity of the voltage applied to each pair of electrodes then determines whether the white or black side is face-up, thus giving the pixel a white or black appearance.

The spheres of the Gyricondisplay are trapped in the oil- filled cavities of an elastomer. Positioning them with a positive or negative voltage puts them into the reflecting [left] or light-absorbing [right] black state. Prototypes have been fabricated at Xerox' PARC.
GyriconE-Paper by Xerox

Electrophoretic Display
•The electronic ink display from E Ink is based on encapsulated electrophoretics
--microcapsules containing many tiny white pigment chips, or particles, that are suspended in a blue-black liquid dye.
•Applying an electric field moves the particles about; the microcapsules can be switched into the reflecting [left] or absorbing [right] state by applying a positive or negative voltage across the indium-tin oxide (ITO) electrodes.

Electrophoretic Display
•Any kind of electrophoretic display relies on electrostatic migration of light- scattering particles in a dyed colloidal suspension.
•When a positive voltage is applied, the particles migrate electrostatically toward the electrode on the viewer side.
•If white light-scattering particles are used, a near-Lambertianreflection can be obtained.
•When a negative voltage is applied, the particles move to the electrode on the side away from the viewer and become hidden behind the dye; the viewer sees the color of the dye.
•Once migration occurs under either polarity and the voltage is removed, the white particles stay in place, creating a bistablememory device.

Electrowetting Display
Based on the phenomenon of Electrowetting effect-controlling the shape of a confined water/oil interface by an applied voltage.
With no voltage applied, the (coloured) oil forms a flat film between the water and a hydrophobic (water-repellent) insulating coating of an electrode, resulting in a colouredpixel.
When a voltage is applied between the electrode and the water, the interfacial tension between the water and the coating changes. As a result the stacked state is no longer stable, causing the water to move the oil aside.
This results in a partly transparent pixel, or, if a reflective white surface is used under the switchable element, a white pixel.

ElectrofluidicDisplays
•Electrofluidicdisplays are a variation of an electrowettingdisplay.
•Electrofluidicdisplays place an aqueous pigment dispersion inside a tiny reservoir.
•The reservoir comprises <5-10% of the viewable pixel area and therefore the pigment is substantially hidden from view.
•Voltage is used to electromechanically pull the pigment out of the reservoir and spread it as a film directly behind the viewing substrate.
•As a result, the display takes on color and brightness similar to that of conventional pigments printed on paper.

ElectrofluidicDisplay

Interferometricmodulator (Mirasol)
•Technology used in electronic visual displays that can create various colors via interference of reflected light.
•The color is selected with an electrically switched light modulator comprising a microscopic cavity that is switched on and off using driver integrated circuits similar to those used to address liquid crystal displays (LCD).

MirasolDisplay

Comparison Of E-paper & LCD
Electronic Ink Display
Liquid Crystal Display
Wide viewing angle
Best image only from one position
Readable in sunlight
Can be difficult to see in sunlight
Holds image without power drain
Required power to hold images
Plastic or glass
Glass only
Light Weight
Power supply and glass make LCDs relatively heavy
Thin (~1 mm)
Thick (~7 mm)

Power consumption
This analysis done for E ink triton.
Mechanical / Dimensional for 6" Display:
Electrical specifications:
Supply Voltage:
2.7—3.3 V DC
Power Consumption:
Active update peak: 1800 mWActive update typical: 750 mWStandby typical: 1 mW

Merits of E-paper
Paper-like readability
Persistent without power, drawing current only when they change, which means low power consumption
Batteries can be smaller and last longer.
•Display module is thinner, lighter weight, and more robust than conventional LCD's.
•Highly flexible and it is able to be twisted or bended into different curvatures.
•The electronic paper can be applied to different shapes of products, without being limited to being bonded to flat display panels.
•They are completely reflective requiring no backlight.
•They are inherently bi-stable for extended periods of time.

Demerits of E-paper
Electronic paper technologies have a very low refresh rate compared to other low-power display technologies, such as LCD.
An example of this limit is that a document cannot be smoothly zoomed without either extreme blurring during the transition or a very slow zoom.
A shadow of an image may be visible after refreshing parts of the screen. Such shadows are termed "ghost images", and the effect is termed "ghosting“.
Because of ghosting the entire screen white and black when loading a new image.

An e-ink screen showing the "ghost" of a prior image
An e-paper display on a watch refreshes to remove ghosts.

Applications
• Wristwatches
• e-Book reader
• eg: Amazon kindle.
• Electronic Shelf Label
• In a large department store or supermarket, e-paper can be
used for labelling the shelves and price tagging.
 Smart Card Display
 Some credit cards contain a smart card to store information such
as accumulated credit and money expenses etc.
 Mobile phones
 E-Newspaper
 Time Table at Stations

•Electronic Billboards
•Status displays
•Digital Photo Frames

Conclusion
Electronic ink is not intended to diminish or do away with traditional displays. Instead electronic ink will initially co-exist with traditional paper and other display technologies.
In the long run, electronic ink may have a multibillion-dollar impact on the publishing industry.
Ultimately electronic ink will permit almost any surface to become a display, bringing information out of the confines of traditional devices and into the world around us.

References
Flexible and Roll-able Displays/Electronic Paper A Brief Technology Overview Rong-Chang (R.C.) Liang
Paper Electronics and Electronic Paper
by Magnus Berggren*'**, Thomas Kugler*'**, TommiRemonen*, David Nilsson**,MiaoxiangChen**, PetronellaNorberg"*The Research Institute ACRE0 AB, Bredgatan34, SE-602 21 Norrkoping, Sweden **Organic Electronics Group, Campus Norrkoping, SE-601 74, Sweden
E-paper: Clarifying future R&D needs by a fundamental understanding of the maximum performance of current technologies
Author(s): Heikenfeld, J. Novel Devices Lab., Univ. of Cincinnati, Cincinnati, OH, USA
http://en.wikipedia.org/wiki/Electronic_paperhttp://spectrum.ieee.org/consumer-electronics/portable-devices/lighter-brighter-displays
Image taken from: http://www.eink.com/technology.html
http://www.amazon.in/gp/product/B007RF5F0Q/ref=famstripe_kp3