It wasn’t that long ago that your computer monitor took up your entire desk and moving it was definitely a two-man job. Flat panel displays (FPD) completely changed the market with lighter and thinner displays freeing up precious space on your office desk and in your home as monitors and televisions were streamlined.
The continued evolution of FPD technology subsequently enabled the ubiquitous rise of portable devices: mobile phones, PDAs, e-readers and now tablets. Whilst the functionality of these devices has changed dramatically over the years, the display itself has remained a rigid, rectangular component with several layers of glass. This brings us to the next disruptive revolution in display technology that is now underway: plastic displays.
Plastic Logic recently announced that its electrophoretic EPD-based plastic flexible displays are commercially available for product integration. This new generation of displays are slimmer, lighter and much more durable than their glass counterparts, with extremely low battery consumption. Since they can be fabricated in any shape and conformed to any surface they will enable truly unique product form factors.
Flexible displays enabled by plastic electronics have caught the imagination of science fiction writers and product designers for decades, but it seemed that the technology could never transition past the prototype stage. This was primarily due to the challenges of carrying out precision engineering on plastic. The first obstacle lies in the mere handling of such thin plastic films through a multiple-stage fabrication process.
Whilst flexibility may be an attractive product feature, it definitely represents a manufacturing headache. For example, a standard display in your e-reader device will have over 150 pixels in every square inch and its fabrication demands structuring to dimensions several times thinner than a standard sheet of paper. A thin plastic sheet simply does not have the same dimensional stability as a sheet of glass, which made it difficult to develop a consistent display making process.
Temperature is another challenge. The traditional FPD fabrication process includes several bake steps at temperatures well over 300°C. Standard engineering plastics are designed to melt at temperatures below 200°C to make it viable to cast or mould them in their molten state. It is clear that innovative thinking and manufacturing methods were required to turn this from mere science fiction in to reality.
The presence of flexible displays on the technology roadmap of every major display maker means there are several tactics being explored to overcome these considerable challenges. Plastic Logic’s specific journey to developing a manufacturing process for flexible displays has run in parallel with and to a certain extent also been a driving force behind the development of the plastic electronics industry.
The foundation of this industry was motivated by the vision that a new class of plastic materials can perform the same semiconductor functions as silicon. For Plastic Logic replacing the active silicon component with a plastic has resulted in several advantages for the fabrication of flexible displays. It enables a much lower temperature profile during fabrication, which in turn allows us to use standard polyester films. Another benefit is the improved dimensional stability at lower processing temperatures. Finally, using the plastic electronics approach has allowed us to not only remove the glass, but also several other brittle ceramic layers normally used in display fabrication. As yet, Plastic Logic is currently the only company worldwide with a process and volume manufacturing facility capable of reliably producing flexible plastic displays at yields comparable to that of the LCD industry. Nevertheless, market research companies recognise that this is indeed a market destined for considerable growth. According to Transparency Market Research, the market for displays enabled by organic or plastic electronics will be worth $16,740 million in 2018.
Lab to fab
For flexible plastic displays the transition from lab to fab is now complete. Plastic Logic can reliably manufacture monochrome and colour flexible EPD display components in a wide variety of shapes and sizes. The next challenge is finding innovative product designers to make the best use of the unique form factors enabled by these displays. Their extreme durability makes them attractive for traditional e-readers in challenging environments such as schools or factories. Furthermore, a great wealth of applications for this breakthrough technology exists, some of which are already known and others have yet even to be discovered. For example, Gartner, Inc. sees a potential market for flexible displays being used for advertising wrapped around columns in shops or in window displays, which communicate with potential customers, displaying personalised adverts on their smartphones as they pass by. In general, as the display size increases it will be the weight that becomes the most attractive feature, with peripheral devices for your smartphones emerging that will have the look and feel of a sheet of paper. As the display size decreases it will be the formability of the display that will create new markets. For example, imagine a watch that has the information density of your smartphone, but actually wraps around your wrist!
At Plastic Logic we believe that in a few short years we will recall that the flexible display was only the start of a wave of plastic electronics enabled products. This can be illustrated best by breaking down the technology that enables a flexible display: A flexible plastic display component is comprised of a frontplane, which is the display effect, and a backplane that is fabricated using plastic electronics. In a display the backplane operates as an output device with its high density array of switches supplying the correct voltage levels to every pixel. However, these backplanes can also be used as an input device and there is currently considerable interest in flexible sensor technologies. One example is a digital x-ray sensor that can conform to the body thus becoming a much more effective imaging device.
The backplane itself is actually comprised of millions of individual transistors, which now can be reliably fabricated on a plastic sheet. In the future, smart packaging will include a series of these transistors configured to complete complex logic operations to offer end-users additional security or brand promotion opportunities for products. Plastic electronics is a young technology, which at its core represents the transition from traditional rigid manufacturing paradigms to more customisable techniques. Eventually it will dovetail with the emerging 3D-printing revolution to allow consumers the ultimate flexibility in designing new products.
The rise of the silicon industry was best illustrated by Moore’s law, which motivated an entire industry to compress as much processing power into the smallest area possible. The equivalent view for the plastic electronics industry will be the complete opposite: processing circuitry will be processed over ever expanding areas to make every surface you contact ‘smarter’. Compared with the silicon industry, plastic electronics has come a long way in a very short time. For our flexible display technology Plastic Logic is seeing interest as diverse as e-readers to displays on kettles. This is instructive to other market sectors for flexible electronics in the future, where an equally diverse range of applications will in all likelihood emerge.
Mike Banach is Senior Research Manager at Plastic Logic Ltd