ELECTRONIC PAPER

By Avinash Arun

contents Past and the future… What is e-paper? Desirable features of E-paper and it’s advantage over LCD

display Comparison of displays Various E-paper technology and companies designing

frontplane and backplane of e-paper 1) Electrophoretic technology 2) Cholesteric Liquid Crystal Display Technology 3) Electrowetting Technology 4) Electrochromic Technology 5) Interferometric Modulator Technology 6) Photonic crystal technology 7) REED(Reverse Emulsion electrophoretic Display) Technology

What urged researchers to design E-paper? Required future developments Current state of research applications

What is e-paper?

An Electronic Paper Display is a display that possess

• a paper-like high contrast appearance

• ultra-low power consumption• a thin, light form.• It gives the viewer the experience

of reading from paper, while having the power of updatable information.

Features of E-paper……

Form-Thin, light weight, shatterproof,

flexible.

Power-Ultra low

power

Look-Bright ,high contrast, full

viewing angle and sunlight

readable.

Advantage over LCD display•LCD display- back-litE-paper-uses ambient light.•LCD display- monostableE-paper display-bistablePower requirement.

Comparison of displays

E-readerPaper

ReadabilityMobility

Phone

Actuality/interactivity

Phone

PDA

Paper

Paper

Laptop

PC

E-reader

E-reader

+

+

+BB

BB

PDA

LaptopPC

Phone PDALaptop

PCBB

Various e-paper frontplane technology Electrophoretic Technology E Ink SiPix Bridgestone

Cholesteric LCD Technology Fujitsu Hitachi Kent Display Kodak Nemoptic ZBD Display

Electrowetting Technology Liquivista

Electrofluidic Technology• Gamma Dynamics

• Electrochromic Technology• Acreo• Aveso• Ntera• Siemens

•Interferometric Modulator Technology•Qualcomm

•Photonic Crystal Technology•Opalux

•REED Technology•Zikon

Companies designing backplane of e-paper areHPNECPlastic LogicPolymer VisionPrime View InternationalRicohSamsungSeiko Epson

1) Electrophoretic technology

Works on the basic principle of electrophoresis

2) Cholesteric Liquid Crystal Display Technology

• It uses chiral nematic Liquid Crystal (LC) molecules confined between two parallel substrates to define the liquid crystal cell.

• Bistable liquid crystal phases exists

• The planer texture reflects the light of specific wavelength

• The conical texture weakly reflects the light.

• Multicolored Ch-LCD can be used by using layers of three primary colors stacked on the top of each other

Planer texture

Conical texture

3) Electrowetting Technology

With no voltage applied, the (colored) oil forms a flat film between the water and a hydrophobic (water-repellent), insulating coating of an electrode, resulting in a colored pixel. Applying voltage between the electrode and the water causes the interfacial tension to change, which causes the water to move the oil aside. The result is a partly transparent pixel; if a reflective white surface is used under the switchable element, a white pixel results.

Change in colour due to oxidation or reduction state.Polyaniline and polyethylenedioxythiophene (PEDOT)

are examples of electrochromic materials.High contrast because it absorbs some colours and

reflects others

5) Interferometric Modulator Technology

4) Electrochromic Technology

• Reflects light at a specific wavelength and gives pure, bright colors like those in a butterfly’s wings

• MEMS are used to switch the display on and off.

6) Photonic crystal technology•Photonic crystals•Changing the pattern of molecules in the crystal causes a change in the color of light that the crystals reflect

Disadvantages• When pixels change from long wavelength colors to shorter ones the speed decreases• Its dependence on the flow of electrolyte in response to electricity

7) REED(Reverse Emulsion electrophoretic Display) Technology

uses nano-droplets of a polar liquid dispersed in a non-polar liquid

use less energyfaster switching speedsvideo possibleCan be produced using LCD

manufacturing technique.

What urged researchers to design E-paper?

Lack of a useable e-reader◦Most reading devices use LCDs,

which use backlights High power, hence low battery life Fatigue due to screen flicker

◦Most reading devices are small. Difficult to read Can not maintain original content layout

◦If not, they are heavy. Laptop, computers

Required future developments Full color implementation Implementation of video on it. Flexibility of the e-paper such that it can be rolled or

folded Develop it in the such that it will reflect infra red rays

and the documents can be read by using night vision camera only. So that it can be used by military. For security purpose.

LCD has a backplane lightning which consumes much power.

So , in case of low power state the same LCD screen can be made to work as a E-paper with no back light on.

Current state of research

applicationsEducation: digital schoolbooksWristwatchesNewspapersCell phones-Motorola's low-cost

mobile phone, the Motorola F3, also uses an alphanumeric black/white electrophoretic display.

The commercial goods with full color display are expected to be in market within a decade.

Thank you