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New technologies make smartphone displays brighter while lowering power consumptionStage Image

New technologies make smartphone displays brighter while lowering power consumption

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Liquid crystals

An award-winning research process

2016/5/11

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In the development of innovative liquid crystals, Merck KGaA, Darmstadt, Germany, is building on the ideas of many. Important input is provided not only by the company’s own basic research, but also by customers. This is the only way that major progress can be achieved.

  • Mark Verrall heads Research and Development (R&D) within the Display Materials business unit of Merck KGaA, Darmstadt, Germany
  • Mark Verrall heads Research and Development (R&D) within the Display Materials business unit of Merck KGaA, Darmstadt, Germany
    © Merck KGaA, Darmstadt, Germany

    Anyone who regularly reads the advertisements for new smartphone models will discover big changes from one generation to the next. For example, the display of high-end smartphones in 2012 had a typical contrast ratio of 800:1. Two years later, they already had a contrast ratio of 1,400:1. This leap was supported by ultra-brightness fringe field switching (UB-FFS), a multiple award-winning liquid crystal technology from Merck KGaA, Darmstadt, Germany.

    Liquid crystals: The crucial difference


    The contrast ratio is a value that expresses the maximum difference in brightness between black and white pixels. The higher this value is, the sharper and more vivid the image appears. However, there are factors that set physical limits to this value.

    One of these factors is a display’s resolution. To develop displays with increasingly higher resolutions, each individual dot or pixel in the display must become smaller and smaller. This reduces the intensity of light that can be transmitted by the liquid crystal layer, leading to lower brightness and therefore less brilliant displays.
  • Merck KGaA, Darmstadt, Germany, manufactures its liquid crystals where the displays are produced, for example here in JapanEnlarge
  • Merck KGaA, Darmstadt, Germany, manufactures its liquid crystals where the displays are produced, for example here in Japan
    © Merck KGaA, Darmstadt, Germany

    One solution could be to increase the power of the display backlight, but this would inevitably drain the battery too quickly. Power sources are especially overtaxed by videos displayed on smartphones at full brightness. Although such videos are displayed in brilliant colors, the viewing experience is relatively short-lived.

    This is where UB-FFS technology comes into play because it can substantially reduce the physical limits. UB-FFS mixes and switches liquid crystals so cleverly that around 15% more light can penetrate from the background lighting through the highest-resolution displays. As an added benefit, it also reduces energy consumption by up to 30%. UB-FFS technology is already being used in many smartphones and tablets. In 2014, Merck KGaA, Darmstadt, Germany, received the Meyer-Galow prize for business chemistry for UB-FFS – followed by the German Innovation Award in 2015.

    Targeted research in a global network


    However, such quantum leaps do not occur by chance; they are the result of well-organized planning. “We have a long-term vision and a fast-paced research roadmap,” says Mark Verrall, who heads Research and Development (R&D) within the Display Materials business unit of Merck KGaA, Darmstadt, Germany. “In addition, we have based our R&D process on several pillars and networked it worldwide.”

    “Our basic research helps us to completely rethink matters.“

    Mark Verrall
    R&D Displays
    Merck KGaA, Darmstadt, Germany

    Verrall himself is a fantastic example of how the company networks its employees. He has been working for the company for the past 25 years. After initially working in Chilworth, United Kingdom, he spent seven years in Taiwan and has been at headquarters in Darmstadt since early 2015. Verrall points out that employees can of course also go on short assignments abroad. “We also send our experts to work with our R&D teams around the world, often for three to six months at a time,” he says. “Although that’s not enough time to complete an entire project, it really helps to create networks and enable the participants to get to know other cultures.”

    UB-FFS technology

     
     

     

  • A technology from Merck KGaA, Darmstadt, Germany, is frequently behind the brilliant liquid crystal displays of smartphones and tablets. The latest variant, UB-FFS, makes displays even brighter while lowering power consumption. So how does this technology, which is collecting one award after another, actually work?Enlarge
  • Unpolarized light, which is produced by an LED, for example, is like sunlight or the light from an incandescent bulbEnlarge
  • Polarizer: Modern displays use backlighting with white light from LEDs. However, this light is a mixture of electromagnetic waves oscillating in all directions. It therefore has to pass through a polarizer on its way to the display surface. This filter lets through waves oscillating in one specific direction. This is essential for the rod-shaped liquid crystal molecules to be able to visibly control the lightEnlarge
  • The glass substrate is the mechanical backbone of an LCD. It carries all of the layers and filmsEnlarge
  • ITO electrode: The ITO layer is made of indium tin oxide (ITO) and is both transparent and electrically conductive. The UB-FFS (ultra-brightness fringe field switching) technology requires electric stray fields. These are produced by the two ITO layers. Of course, these layers must be separated by an insulating layer which prevents direct contact between the two electrodesEnlarge
  • Insulating layerEnlarge
  • The orientation layer "orients" the LC molecules parallel to the glass plates. In a further step, the long axes of all of the molecules can be set to point in the same directionEnlarge
  • Polarized lightEnlarge
  • Liquid crystals: A liquid crystal is a hybrid of a liquid, whose molecules are disordered and can move freely, and a crystal, which has a strict spatial order. Thanks to their physical properties, they can rotate the direction of oscillation of polarized light. The liquid crystal layer is the key to this. The layer must make optimal use of the light, as the polarizer only passes half of it. This is where the latest-generation technology comes in. The liquid crystal layer of the “ultra-brightness” variant (UB-FFS) passes 15% more of the background illumination than its predecessor, FFS technologyEnlarge
  • Color filters make the primary colors — red, green and blue — from white lightEnlarge
  • Transmitted light is light that has passed through polarizers and color filters. Its intensity depends on the liquid crystals that are controlled by the electrodeEnlarge
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    In addition to the employees’ expert knowledge, such networks are a key precondition for ensuring that the R&D process for liquid crystals remains productive. This process is based on four pillars: searching for new materials, technically integrating these materials into finished components, making customer-specific adaptations, and transferring tested prototypes to mass production.

    The R&D process also depends on innovative ideas, which come from a wide variety of sources.

    Important input is provided by the customers who manufacture liquid crystal displays (LCDs) in China, Japan, Korea, and Taiwan. Because the global production of LCDs is concentrated in these four countries, Merck KGaA, Darmstadt, Germany, has set up its own facilities there. This allows local teams to quickly supply the customers’ varied needs. “Customers typically give us just ten days’ time to develop individualized new product samples,” says Verrall. Customers may have special requests regarding the color brilliance, for example, or the switching speed of the liquid crystals. To meet such requests, Merck KGaA, Darmstadt, Germany, relies on its broad range of in-house developments and production capabilities. As a result, the company can deliver its own components for eight of the up to ten layers contained in a modern liquid crystal display.

    More demanding future-oriented projects are managed from Central Research in Darmstadt, where specialists conduct a more thorough search for solutions at the material and technical levels. Here, interdisciplinary teams of chemists, physicists, and engineers work hand in hand, adapting new chemical formulations to specific display technologies so that they can offer the client a choice of different possibilities. As was the case with the development of the UB-FFS technology, this process typically takes two to three years.

    Liquid crystals can even control windows


    Merck KGaA, Darmstadt, Germany, has also set itself a longer-term vision that looks beyond current technology to the future. Its researchers are pursuing groundbreaking projects that can take five to ten years to complete. “This basic research helps us to completely rethink matters and even create entirely new applications for our materials” says Verrall.

    2016/5/11

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    As part of its LC 2021 initiative, the company aims to make liquid crystals marketable for other applications besides displays. For example, liquid crystals are to regulate the transparency and heat transmittance of windows in building facades by quickly and efficiently switching the glass between bright and dark. Such technology has already been installed into a whole wall of windows at the company’s Innovation Center in Darmstadt. Cooperation partners from the glass and window industries will help market this promising new technology in the future.
     
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