TABLE OF CONTENTS

TABLE OF CONTENTS

ABSTRACT
TABLE OF CONTENTS

1.INTRODUCTION
2.EVOLUTION
3.POLYMER VISION
4.WHAT IS A ROLLABLE DISPLAY
5.THE TECHNOLOGY BEHIND
a.ORGANIC THIN FILM TRANSISTER
b.POLYMER ELECTRONICS
c.E-INK
i.GYRICON TECHNOLOGY
6.HOW DO U MAKE A ROLLABLE DISPLAY
a.ACTIVE MATRIX BACKPLANE
b.E-INK FRONT PLANE
7.BENEFITS
8.APPLICATIONS
a.DISTRIBUTED SIGNAGE
b.ENTERTAINMENT
c.GPS
d.ENTERPRISE
9.COMMERCIAL REALISATIONS
a.FIRST GENERATION ELECTRONIC PAPER DISPLAY
b.WORLD’S THINNEST ACITVE MATRIX DISPLAY
c.PHILIPS CONCEPT READIUS
10.FUTURE POSSIBILITIES
11.CONCLUSION
12.REFERENCES

ABSTRACT

Rollable displays are lightweight, large-area displays that are unbreakable and can be rolled up into a small-sized housing when not actively used. The displays combine active-matrix polymer driving electronics with a reflective ‘electronic ink’ front plane on an extremely thin sheet of plastic. The availability of such displays would greatly stimulate the advance of electronic books, newspapers and magazines, and also new services offered by (third generation) mobile network operators. These applications currently depend on fragile, heavy and bulky laptops or small, low-resolution displays of mobile phones, which both have clear drawbacks. Within the Philips Technology Incubator an internal venture has been formed with this aim. The venture is called Polymer Vision

INTRODUCTION

The display is the interface to the networked society; it forms the essential link between information and the human being. The major trends to be noted in this respect are the increasing demand for pervasive Mobile/Wearable terminal displays, requiring the introduction of rugged, lightweight and flexible display interfaces, and ubiquitous displays of any shape and size based on new enabling process technologies, with cost-effective production methods.

Reflective displays with paper-like viewing characteristics are rapidly emerging, with applications like electronic books and newspapers, roaming data access, and, on the longer term, full-color video access on the move.

For years, the "holy grail" of the display industry has been a thin, clear, flexible substrate with barrier properties equal to those of a sheet of glass. Flexible displays offer many potential benefits over other display technologies, including reductions in weight and thickness, improved ruggedness, and nonlinear form factors. These features make flexible displays attractive for a variety of electronic products ranging from cell phones and PDAs to computers, toys, electronic books, and "wearables."

EVOLUTION

The manufacturing of flat panel displays is a dynamic and continuously evolving industry. Improvements of flat panel displays are made rapidly as technology improves and new discoveries are made by display scientists and engineers. The cathode ray tube and active matrix liquid crystal display (LCD) recently celebrated their 100th and 25th anniversary, respectively. The arrival of portable electronic devices has put an increasing premium on durable, lightweight and inexpensive display components. In recent years, there has been significant research investment in the development of a flexible display technology.





Organic LEDs on glass substrates are already making their way into consumer products such as digital cameras and electric shavers, but the first products to incorporate flexible displays will likely be electronic books, paper, and signage. While products are initially being built on glass substrates, the shift to flexible substrates is under way.


Rollable-display initially focused on electrophoretics, a low-power-consumption display technology better known for its role in e-paper, e-books, and e-signage.Gyricon's Smart Paper, for example, is produced in a roll like conventional paper but is actually two sheets of thin plastic with millions of tiny bichromal beads embedded in between. E Ink uses stationary microcapsules that contain white particles, black particles, and a clear fluid OLEDs are self-luminous and do not require backlighting, polarizer, or diffusers, which reduces the size and weight. In addition, they offer a wide viewing angle and low power consumption. While OLEDs are not yet as bright as other displays, efforts are under way to improve this. When it comes to putting OLEDs on polymer or metal-foil substrates, proponents say there is a symbiotic relationship between the materials and the production processes that make OLEDs a natural fit for flexible displays.

It turns out that the OLED manufacturing process, because it is all chemical, is much more amenable to retaining optimum performance on a flexible surface than other display technologies such as LCDs.There are still some key technology limitations to be overcome—most notably the extreme sensitivity OLEDs have to moisture and oxygen. Another key factor in transitioning OLED, LCD, and electrophoretic displays onto polymer or metal involves the TFT backplanes, which must also eventually reside on plastic in order to achieve a truly flexible display.

Another approach is to eliminate the temperature issue altogether by using organic transistor materials for TFTs that can be printed directly on plastic.
Polymer Vision, a division of Philips, has been able to make organics-based QVGA (320 × 240 pixels) active-matrix displays with a diagonal of 5 in., a resolution of 85 dpi, and a bending radius of 2 cm. The displays combine a 25-µm thick active-matrix backplane containing the polymer electronics-based pixel drivers, with a 200-µm front plane of reflective "electronic ink" developed by E Ink (see photo, [right]). With nearly 80,000 TFTs, the resulting display is the largest organic electronics–based display yet.

POLYMER VISION

Polymer Vision NV (Eindhoven, Netherlands) is a business initiative within the Philips Technology Incubator aiming to bring flexible displays to market by combining polymer electronics with electronic ink.

Polymer Vision builds on years of groundbreaking research in the field of organic electronics within Philips Research, which earlier led to world-first demonstrations of organics-based, functional RFID circuits and active-matrix displays. One key competence of Polymer Vision is the robust fabrication of large arrays of polymer based thin-film transistors (TFTs) with largely identical electrical characteristics. This is combined with the capability to model and design circuitry that exploits the characteristics of organic electronics to the fullest.

By combining active-matrix polymer driving electronics with a reflective electronic ink front plane on an extremely thin sheet of plastic, Philips is capable of producing the world’s thinnest flexible active-matrix display to date. Philips Polymer Vision's rollable display is well positioned to accommodate the user with smooth, paper like viewing in all sorts of data-centric mobile applications, such as text, agendas, e-mail, electronic maps, and multiple-data information services.

WHAT IS A ROLLABLE DISPLAY

The display is an organics-based, QVGA (320 × 240 pixels) active-matrix display, 5 in. on the diagonal, and 85dpi (see Figure 4). The display layers a 200-micron thick, reflective Electronic-Ink display from E Ink Corporation (www.eink.com) on top of a 25-micronthick, active-matrix plane.

Key Features

Big screens in small devices
High resolution
Robust / unbreakable
Feather weight
Paper-like readability under any light conditions
Low power consumption
Enable revolutionary product designs and form factors

THE TECHNOLOGY BEHIND

Proven Building Blocks

Although rollable displays are truly revolutionary, the technologies behind them - TFTs (Thin Film Transistors), polymer electronics and electronic ink - are tried and tested. Polymer Vision can draw on over 20 years of experience in polymer electronics and flat display technology. Also, the electronic ink currently used, is based on technology already integrated into commercial products such as e-books. The processing techniques involved in manufacturing rollable displays are widely used in today's semiconductor and display industries. So the move to mass production does not require complex, unproven equipment or processes. The display combine active-matrix polymer driving electronics with a reflective electronic ink" front plane on an extremely thin sheet of plastic. The flexible, active-matrix backplane has a thickness of only 25 microns " one-quarter the thickness of a sheet of paper " contains a 200-micron frontplane of reflective electronic ink. Polymer Vision also developed shift registers based on organic electronics.

ORGANIC THIN FILM TRANSISTORS

Organic thin-film transistor (OTFT) technology involves the use of organic semiconducting compounds in electronic components, notably computer displays. Such displays are bright, the colors are vivid, they provide fast response times, and they are easy to read in most ambient lighting environments.

Several factors have motivated engineers to conduct and continue research in organic semiconductor technology. One of these factors is cost. Organic displays are relatively cheap, but until recently, they have proven slow in terms of carrier mobility (the ease with which an atom shares electrons and holes with other atoms). Slow carrier mobility translates into sluggish response time, which limits the ability of a display to render motion such as is common in animated computer games and, increasingly, on the Web. However, a process for growing organic crystals with carrier mobility rivaling that of traditional TFT materials has been developed.

Another factor that motivates research in OTFT technology is application diversity. Organic substrates allow for displays to be fabricated on flexible surfaces, rather than on rigid materials as is necessary in traditional TFT displays. A piece of flexible plastic might be coated with OTFT material and made into a display that can be handled like a paper document. Sets of such displays might be bundled, producing magazines or newspapers whose page contents can be varied periodically, or even animated. More likely, such displays will find use in portable computers and communications systems.

POLYMER ELECTRONICS

The kind of electronics which deals with new electrically conducting and semi- conducting organic polymers is called polymer electronics. In dependence on their chemical structure plastics may exhibit electrically conductive, semi-conductive or insulating properties. The insulating quality of organic materials, especially of polymers, has long been deployed in the field of electrical engineering. With the deployment of such materials for electronic applications, the words "polymer electronics" were shaped. They are derived from their chemical structure, which contains so-called "conjugated polymer main chains", consisting of a strictly alternating sequence of single and double bonds. Consequently, these polymers possess a delocalized -electron system giving it semi-conducting properties, and after chemical doping can even be made conductive. Additionally to their conducting or semi conducting features, these materials can - under certain circumstances - emit light and therefore be used in organic light-emitting diodes, so called OLEDs.Polymer electronics is thin and flexible and is printed onto a polyester film in several layers.

E-INK CORPORATION

Electronic ink is a proprietary material that is processed into a film for integration into electronic displays. Although revolutionary in concept, electronic ink is a straightforward fusion of chemistry, physics and electronics to create this new material. The principal components of electronic ink are millions of tiny microcapsules, about the diameter of a human hair. In one incarnation, each microcapsule contains positively charged white particles and negatively charged black particles suspended in a clear fluid. When a negative electric field is applied, the white particles move to the top of the microcapsule where they become visible to the user. This makes the surface appear white at that spot. At the same time, an opposite electric field pulls the black particles to the bottom of the microcapsules where they are hidden. By reversing this process, the black particles appear at the top of the capsule, which now makes the surface appear dark at that spot.

GYRICON TECHNOLOGY

Electronic paper was first developed in the 1970’s by Nick Sheridon at Xerox’s Palo Alto Research Center. The first electronic paper, called Gyricon, consisted of polyethylene spheres between 20 and 100 micrometres across. The basic Gyricon display technology consists of a sheet of silicone elastomer in which many round spheres are embedded. The spheres are smaller than the eye can see and are made so that one hemisphere is one color and the other is a contrasting color. In addition to a different color, each hemisphere also has a different electronic charge. Every ball floats in its own small cavity, which is filled with silicone fluid. An electric field across the sheet can cause the ball to rotate. When the field is turned off, the ball settles against the cavity wall. Electrostatic forces maintain that state of rotation until an opposite electric field is applied, thus achieving bistable operation. Patterned electrodes allow us to rotate balls in selected areas, thus creating an image on the display. This is achieved by laminating the sheet between an electronic backplane and a transparent top electrode.

For situations in which the user needs central control of signs spread around a building or campus, these displays can be updated via a wireless router. One piece of software can control hundreds or thousands of signs if the designer assigns each sign its own network address and stores each sign's layout in the software scheduler. This program looks like commonly available scheduling software: any message can be scheduled for any time slot. Once programmed into the scheduler, the appropriate message appears on the sign at the appropriate time, whether it is a one-time message or a recurring message programmed far in advance.

HOW DO U MAKE A ROLLABLE DISPLAY

Using glass as a substrate (base) isn’t an option, as glass doesn’t bend. Thin plastic films are ideal, but they melt if you use the high process temperatures normally involved in manufacturing silicon-based TFTs (Thin Film Transistors) like those used in laptop displays.

The answer lies in organic/polymer TFTs. These can be made using low temperature processing techniques, so you can use plastic as a substrate for the TFT layer. Together, the base and the TFT layer are just 25 μm thick.



On top of this base and TFT layer, you still need a display effect technology that’s also flexible enough to roll – such as the electronic ink we’re using today By combining active-matrix polymer driving electronics with a reflective electronic ink front plane on an extremely thin sheet of plastic we get a rollable display.

ACTIVE MATRIX – BACK PLANE

In an active-matrix display, each pixel is connected to its corresponding row and column electrodes by one or more transistor switches. These transistors allow the pixel to remain in the defined ‘on’ or ‘off’ state, even when the row in which the pixel resides is not being addressed. The image represented by each row of pixels therefore remains static until the row is re-addressed, eliminating the possibility of flicker.





Further development of large, flexible displays requires a cost-effective manufacturing process for the active-matrix backplane, which contains one transistor per pixel. One way to further reduce costs is to integrate (part of) the display drive circuitry, such as row shift registers, directly on the display substrate. Here, we demonstrate flexible active-matrix monochrome electrophoretic displays based on solution-processed organic transistors on 25-m-thick polyimide substrates. The displays can be bent to a radius of 1 cm without significant loss in performance. Using the same process flow we prepared row shift registers. With 1,888 transistors, these are the largest organic integrated circuits reported to date. More importantly, the operating frequency of 5 kHz is sufficiently high to allow integration with the display operating at video speed. This work therefore represents a major step towards 'system-on-plastic'.

ELECTRONIC INK-FRONT PLANE

To form an E Ink electronic display, the ink is printed onto a sheet of plastic film that is laminated to a layer of circuitry. The circuitry forms a pattern of pixels that can then be controlled by a display driver. These microcapsules are suspended in a liquid "carrier medium" allowing them to be printed using existing screen printing processes onto virtually any surface, including glass, plastic, fabric and even paper. Ultimately electronic ink will permit most any surface to become a display, bringing information out of the confines of traditional devices and into the world around us.

BENEFITS

Increasingly, business users are demanding access to broadband information while on the move. Rollable displays are projected to be the primary solution to the consequent demand for larger displays in mobile devices -- without increasing device size, weight, or power consumption. Philips Polymer Vision's rollable display is well positioned to accommodate the user with smooth, paperlike viewing in all sorts of data-centric mobile applications, such as text, agendas, e-mail, electronic maps, and multiple-data information services.

Rollable displays are projected to be the primary solution to the consequent demand for larger displays in mobile devices -- without increasing device size, weight, or power consumption.The rollable b/w display could provide a useful additional option to those needing to type and edit on the move, while traveling on airplanes, trains, buses, cars or ships. Those foldable and highly portable keyboards could well carry within themselves also an rolled up b/w display that would give much relief to the strain placed on looking at those tiny and low resolution PDA screens.

APPLICATIONS

DISTRIBUTED SIGNAGE

Signs provide several functions in public buildings, campuses, offices, and stores: they help people find their way, show the schedules of classrooms or conference rooms, and indicate the price of merchandise. With the proliferation of digital information, there are many potential benefits to making signs that can be tied to a database and electronically changed. Difficulties in achieving such displays include the cost of the signs, the cost of installation, the need to supply a source of power to each sign, and the need for software and systems to control the information sent to each sign. Part of the problem can be solved using electronic-paper displays that are inexpensive, easy to read, and lightweight. These signs can run on batteries for months or years because they don't consume power to maintain an image, and they are easy to install because they use reflected light for illumination. A single computer and software system controls all the signs via a wireless connection, and all the signs run on batteries.

ENTERTAINMENT

Larger screens for mobile entertainment

Entertainment is big business in the mobile world – and growing bigger. But few applications look their best on a 2” screen, and larger screens have always required larger devices. With rollable displays, device manufacturers can create compact, distinctive products with large screens. Increasing the appeal by adding to the fun, they’ll be the envy of anyone’s friends.

Today, the sheer size of a rollable display greatly adds to the comfort and ease-of-use of mobile applications. As the technology evolves, it will offer yet more – color, motion video and touch screen functionality, delivering an even richer multimedia experience. The future of the mobile world relies heavily on advanced, fun applications. Devices which support them without growing to the size of laptops will have a huge advantage, attracting consumers and service providers alike. Rollable displays enable large screens on devices which consumers always have with them, tucked away in lightweight, pocket-sized casings. Truly mobile, they are the ideal way to reach out to a mobile customer base of immense proportions.

GPS

Unroll the world of information

GPS and location-based services are ideal application areas for rollable displays. No other display technology combines such a high degree of ‘visual convenience’ with the ability to pack away into a tiny case. When in use, the display opens out to a useful size – similar to a small book – so users can easily see the location they’re interested in, its surroundings and any associated data provided. When not in use, the screen simply ‘disappears’ back into the casing, allowing users to slip the device into a bag or pocket.

This is just one example. The versatility, robustness and low power consumption of rollable displays allow device manufacturers unique freedom to offer a wide variety of new form factors and innovative designs. Screens can be built into portable equipment such as you see here or created as stand-alone devices that access data via wireless connections to other equipment.

ENTERPRISE

The ‘bigger picture’ for business applications

With QVGA resolution, high contrast and low power usage, Polymer Vision's rollable displays are the ideal solution for paper-like reading comfort on mobile devices. These displays enable the creation of compact and rugged products which give user’s convenient access to many forms of simple, but valuable digital visual content such as text information, mail and graphics.

Content can be pushed to an 'accessory' device via a mobile phone wireless connection, or direct to a stand-alone device with its own communication pipe. With the evolution of voice-to-text services, Polymer Vision-enabled rollable display devices can also be a convenient way of receiving, reading and storing larger text messages, making them an attractively simple solution for enterprise users on the move.