Analysis of Surface and Flexible Touch Panel Technology and Development Trend

The popularity of wearable devices has driven the market demand for curved surfaces and flexible display panels. The touch functions necessary for smart mobile devices have also been used by various manufacturers to create their own Curved and Curlable types. Rollable, bendable, and foldable flexible panel technologies and touch solutions enable curved touch functionality to be implemented in small and medium-sized end products. Let's take a look at the techniques and development trends of these curved surfaces and flexible touch panels.

Surface display technology e-paper pioneered

Surface display technology allows smart mobile products to give more space for imagination. According to a study by the research organization TouchDisplayResearch, flat or curved wearable devices will exceed 30 million by 2023, of which the curved touch display market will exceed the $27 billion mark in 2023. Therefore, the surface touch display technology has become a topic that all circles have begun to pay attention to in recent years.

As early as 1974, Nick Sheridon, a researcher at the Parc Research Center (now the PARC Research Center) of Xerox (all recorded), developed the first generation of ePaper display technology and pioneered the surface display technology. The principle and feature is that in the charged ball, one side is painted white, the other side is painted black, and the ball is turned up and down by changing the electric field to present a black and white picture. Until 2003, Xerox founded the Gyricon subsidiary to commercialize its e-paper technology, which is also known as the Gyricon technology. However, its commercialization is too slow. In 2005 Gyricon ended its operations.

In 2004, the U.S. Army set up the FDC (Flexible Display Center) at ASU (Arizona State University) and cooperated with HP (Hewlett-Packard) technology. In 2008, it published the prototype of a flexible, non-breakable electronic paper display for the first time. ASUFDC later turned to OLED display, and subsequently released the largest OLED flexible full-color display panel at SID 2012, measuring 7.4 inches. It was developed from a Mixed Oxide TFT.

ASU stressed that the panel material allows manufacturers to reuse existing production lines to produce, without additional investment in other equipment, more cost-effective. The PEN (polyethylene naphthalate) film substrate of the panel is a Teonex product from Japan Teijin DuPont Film Co., Ltd., which has heat resistance and surface smoothness, and is quickly introduced into mass production.

Founded in 2000, British-based PlasticLogic specializes in the field of polymer transistors and plastic electronics, and produces color and monochrome plastic flexible displays, using its own proprietary organic TFT (OTFT) technology. Distortion and other abilities. The company launched its own plastic screen in 2004 that can be used in newspapers, e-books, and other products, and announced in 2010 that it will launch its own QUE e-book (but later plans to cancel).

As the company's strategy changed, PlasticLogic began to introduce various soft display products of monochrome electronic paper technology (ie, the Pacific Electronics' EInk technology) and color OLED display technology in 2013, and demonstrated 16 single 10.7 inches single in Tokyo. 42-inch large flexible screen prototype product grouped by Flexible Display.

In the accumulation of R&D achievements of previous companies, in 2004, HumanMediaLab (Human Media Lab) of Queen's University of Canada started the PaperWindows development plan, and in 2007, the new term Organic UI (OUI) was introduced to describe non-manipulation. Computer products for flat/non-rigid display technology, this term is also included in the ACM (Computer Association) journal.

The lab collaborated with ASUFDC in 2010 to develop PaperPhone, the world's first e-paper-displayed mobile phone, to be manipulated through gestures. The Lab also partnered with PaperLogic and Intel to publish PaperTab, a prototype PC for flexible PCs and multi-screen e-papers, at CES2013. Then in April, it further announced MorePhone, the world's first flexible smart prototype phone. Touch or bend the screen to manipulate the computer.

Other flexible electronic paper technology R&D part: AUO published its flexible electronic paper technology in cooperation with SiPix (Daiyi Technology, which was incorporated into Yuantai Technology in 2012) in 2009; LG also displayed its 19 in 2010. The inch-flexible E-Paper prototype product; and Sony published a 13-inch electronic newspaper in 2014 (using Enk Mobius technology).

OLED with plastic material surface shows great evolution

When a large number of mobile devices use Flexible PCB (Flexible Printed Circuit Board), there are also manufacturers trying to use plastic instead of TFT glass, so that existing TFTLCD, OLED also has the flexibility to become a display of competing technology companies after 2005 Panel technology, formal products will be listed after 2010.

In 2011, Nokia demonstrated its Kinetic flexible OLED panel and concept mobile phone, which can control the handset through bending amplitude, but it has not been mass-produced. Subsequently, at SID2014, SEL (Semiconductor Energy Research Institute) and AFD (AdvancedFilmDevice) demonstrated their two-fold, three-fold 5.9-inch mobile phone OLED display panel with a resolution of 1280x720 and 249ppi.

This product uses a special panel manufacturing technology, sandwiching the sealant and the flexible base substrate between the color filter, OLED and TFT panel layers, making the shortest radius up to 2mm, 4mm, and can withstand 100,000 folds. . Although the product is later than the two Korean panel makers, it is reported that Apple will adopt its technology and apply it to wearable products (such as iWatch).

In 2005, Sony cooperated with RIKEN to invest in the development of flexible display technology. After launching the world's first OLED TV in 2007, it demonstrated its 4.1-inch rollable OTFT-driven OLED display panel in 2010, followed by 2012 display of 9.9-inch OLED flexible panel with 960x540, 111ppi resolution. After the training of surface display technology became mature, the world’s first 65-inch curved LED TV was exhibited at IFA 2013 with its own Triluminos primary color display technology to provide more realistic image quality. However, the mobile phone has not yet launched a curved screen.

After Samsung acquired OLED technology, its ContourDisplay curved glass screen first appeared on a NexusS curved phone in cooperation with Google in 2010. It adopted a 4-inch SuperAMOLED flat panel and configured curved glass to achieve this. Then Samsung first released a truly flexible AMOLED 4.5-inch panel at CES2011.

Samsung acquired Liquavista with EWD (Electrowing Display) technology in 2010 and was unable to commercialize the EWD technology. It was later resold to Amazon in 2013 and focused on OLED research and development. Its touchable small-sized product is named SuperAMOLED; as for the flexible touch panel, it was named Youm and was first publicized at CES2013; then in August, KN55S9C curved TV (55-inch OLED) was released; and in October, it released the world’s first GalaxyRound curved phone (take 5.7-inch AMOLED multi-touch panel), and released GearFit smart bracelet (take 1.84-inch curved AMOLED touch panel) at MWC2014 exhibition. However, although the panel is bendable, the body cannot be bent, so it cannot be called a flexible mobile phone/bracelet.

The U7800 (78-inch) and U6000 (55-inch) series of curved TVs were recently released in July 2014. They have two options, curved surface and flat surface, and adopt 4200R gold curvature design.

LG, the latecomer to LG, mainly focused on POLED (Plastic OLED) in the research and development of flexible panels, with ultra-thin characteristics, and demonstrated its leading position in surface display technology. Released the 55EA9800 curved TV (55-inch OLED) at CES2013, winning the market with a body thickness of only 4.3mm; in October also announced the GFlex flexible mobile phone (using 6-inch POLED multi-touch panel), 700R radius of curvature The LG has the flexibility to bend the surface of the fuselage and has the ability to heal itself. With the design of the flexible battery, LG calls it the world's first flexible mobile phone.

In July 2014, LG released a 105-inch 21:9 arc-shaped television with a wide screen display to retaliate against its opponent. In addition, LG released an 18-inch “translucent” OLED flexible display panel in July 2014 with a resolution of 1200x810, a 30% transparency, and a deflection radius of 3mm, which will drive new applications for future transparent and flexible display panels.

Asustek is presenting the world's first 32-inch LED curved display concept product at COMPUTEX 2014 with a resolution of 2560x1440WQHD and joining the big manufacturers to join the surface display boom.

Flexible Touch Technology Soft Board Alternatives

Since 2013, curved screen products have been officially launched, and various companies have proposed different touch solutions. Samsung Galaxy Round, for example, uses On-cell touch technology with a glass substrate. LGGFlex is a plastic substrate. In 2010, Apple applied for a patent for a "curved touch sensor" manufacturing method and was officially announced at the end of 2013. This technology adopts a self-fabricated film conductor laminate design, covering the conductor film on the substrate, and then changing the substrate into an arc after the embossing process, and then heating and fixing the surface into a curved shape. This method can ensure touch sensing. The layer is not easily deformed to produce a wavy, flexible touch screen and is applied to its own mobile phones, tablets, and computers.

In addition to the above-mentioned solutions from large manufacturers, various companies have also proposed various curved touch technologies, such as the use of ITO (Indium Tin Oxide) substitutes, to reduce material costs, and at the same time providing flexible solutions with thin film flexible boards. . For example, eTurboTouch and UniDisplay have both published OFS (OneFilmSolution, single-film solution) flexible touch panels, using Cambrios nanosilver as an alternative to ITO materials; Tektronix (TPK) It is through the introduction of flexible substrates and OGS module technology to achieve the ability to display high-quality images at different curvatures.