In this blog post, we explore how e-paper is transforming our daily lives by combining the texture of paper with the functionality of a display.
A man being chased by the police flees, blends into the crowd, and hides in the subway. He looks around to see if anyone recognizes him. Feeling momentarily relieved, he sinks deep into his seat. But then, his eyes suddenly meet those of a man reading a newspaper across from him. The man’s newspaper suddenly updates, displaying a video containing information about the fugitive. The man has no choice but to flee again. This is a scene from the movie *Minority Report*. You may soon be able to see this kind of newspaper—the sort you’d expect to find only in science fiction films—right in your own living room.
This electronic paper, also known as e-paper, is a display that combines the advantages of both paper and traditional screens. The first electronic paper was developed in the 1970s by Nick Sheridan at Xerox’s Palos Alto Research Center under the name Gyricon. In 2007, Amazon created an e-book reader using electronic paper and released it under the name Kindle. Just four years later, Amazon announced that e-book sales had surpassed those of paper books. This rapid advancement in e-paper technology has not been limited to the publishing industry alone but has also brought about new innovations in fields such as education, advertising, and healthcare. For example, there is a growing number of applications using e-paper in digital textbooks, menus, and billboards. In particular, the medical field is taking notice of e-paper because it can convey information with a texture similar to paper, offering the advantage of providing clear, important information without straining patients’ eyes.
Unlike conventional displays, e-paper utilizes reflected light. E-paper contains millions of microcapsules inside, each about the diameter of a human hair (or even smaller). These capsules contain transparent oil and black and white particles with different electrical charges. Electronic circuits run along the bottom surface of the e-paper where these capsules are placed, and the particles move according to the voltage of these circuits. For example, if the circuit running beneath a capsule carries a negative voltage, the positively charged white particles move toward the circuit, while the negatively charged black particles rise to the surface, causing that specific location to display a black dot. This principle of electronic paper is similar to how the positive and negative poles of a magnet attract or repel each other. Thanks to this characteristic, electronic paper has the major advantage of very low power consumption. This is because electronic paper screens only use energy when a voltage is applied and consume almost no power when the screen is static. This has made it possible to develop e-book readers and digital menu boards that can be used for long periods on a single charge.
Conventional displays use a backlight method, where the color to be displayed at each pixel is determined, and light is projected from behind. While they offer the advantages of fast response times and visibility in the dark, they can cause eye strain when viewed for long periods and are difficult to see in areas with intense external light. Anyone who has used a smartphone has likely experienced trying to shield the screen with their hand because it was difficult to see in direct sunlight outdoors. In contrast, e-paper allows for reading outdoors just as if you were reading a physical book, and because it has no flickering or glare, it does not strain the eyes even during prolonged reading. As a result, e-paper provides a natural reading environment and is gaining popularity, especially among those who spend a lot of time outdoors. Furthermore, because e-paper is highly energy-efficient, more and more people are choosing e-books over paper books.
Another feature of e-paper is its flexibility. Since the display works by projecting light from behind, the position of each pixel that receives the light must be fixed. Therefore, even minimal flexibility is not possible. Since the position of the microcapsules in e-paper is not critical and they are small in size, the material can achieve a high degree of flexibility. It is said that e-paper flexible enough to be rolled up like a ballpoint pen has been developed, so it may not be long before we reach the stage where it can be folded and used just like paper. Based on this flexibility, e-paper is expanding into various fields of application. For example, the potential applications are endless, ranging from attachments to clothing and bendable billboards to even wearable smart devices.
However, e-paper also has its limitations. One of these is its inability to display a wide range of colors. While some companies have released products that address this issue, low-cost models for general consumers have not yet been introduced. Additionally, the slow screen response time—due to the physical movement of particles—remains an unresolved challenge. Consequently, current e-paper cannot play videos or run games. Other remaining challenges include the inability to display pure white due to the presence of black particles, as well as relatively low resolution. While these technical limitations still need to be addressed, the advancement of e-paper has not come to a halt. Researchers around the world are studying new materials and processes in an effort to overcome the limitations of e-paper. For example, active research is underway to improve color reproduction and response speeds, and there is a strong possibility that new e-paper with significantly improved performance will emerge in the near future.
Despite the issues associated with e-paper, the number of people attracted to its advantages is steadily growing. As mentioned earlier, sales of e-books on Amazon have surpassed those of paper books, and not only Amazon but also numerous companies both domestically and internationally are releasing e-book readers utilizing e-paper. Since 2007, a middle school in Maastricht, the Netherlands, has been using e-paper as digital textbooks. On the day that e-paper—which combines the best features of both paper and displays—replaces paper, you might find yourself sitting on the couch, sipping your morning coffee, unfolding an e-paper newspaper, and watching a video of yesterday’s summit. The advancement of e-paper will not stop at mere technological innovation; it will bring about changes across our daily lives and the way we consume media. Through these changes, we will be able to enjoy a more convenient and information-rich environment.
