In this blog post, we will look at how electronic paper combines the texture of paper with the functionality of a display to change our daily lives.
A man being chased by the police runs away and hides in a subway car, where he is surrounded by a crowd of people. The man looks around to see if anyone recognizes him. He takes a moment to breathe and sink deeper into the seat. But then, he suddenly catches the eye of a man reading a newspaper across from him. The man’s newspaper suddenly updates, showing a video with information on the wanted man. The man has no choice but to run away again. This is a scene from the movie Minority Report. This newspaper, which looks like something out of a science fiction movie, may soon be seen in your living room.
This electronic paper, also called e-paper, is a display that combines the advantages of paper and display. The first electronic paper was developed in the 1970s by Nick Sheridon at Xerox’s Palo 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 paper book sales. This rapid development of e-paper is not limited to the publishing industry, but has also brought about new innovations in education, advertising, and the medical field. For example, there are an increasing number of cases where e-paper is used in digital textbooks, menus, and billboards. In particular, in the medical field, e-paper, which can convey information with a paper-like texture, is attracting attention for its ability to provide important information clearly without putting a strain on the patient’s eyes.
Electronic paper uses reflected light, unlike conventional displays. Electronic paper contains millions of microcapsules inside it, each the diameter of a human hair (or smaller). These capsules contain transparent oil and black and white particles with different charges. Electronic circuits flow on the bottom of the electronic paper, where the particles move according to the voltage of the electronic circuits. For example, if the electronic circuit flowing under a capsule has a negative voltage, a positively charged white particle approaches the circuit, and a negatively charged black particle floats to the surface, the location corresponding to that capsule is marked with a black dot. The 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, e-paper has the great advantage of consuming very little power. This is because e-paper screens use energy only when voltage is applied, and consume almost no power when the screen is fixed. This has made it possible to create e-book readers and electronic menu boards that can be used for a long time on a single charge.
Existing displays use a backlight method that determines which color to display at each point and shoots that light from behind. It has the advantage of being fast to respond and can be viewed in the dark, but it is tiring to the eyes over the long term and is difficult to see in places with strong external light. Anyone who has used a smartphone has probably experienced the problem of being unable to see the screen outdoors in bright sunlight and having to create a shadow with their hand. In contrast, e-paper can be read outdoors as if reading a book, and there is no flickering or glare, so the eyes do not get tired even after prolonged reading. This makes e-paper a natural reading environment, and it is especially popular with people who are often outdoors. In addition, e-books are increasingly being chosen over paper books because they are more energy-efficient.
Another feature of e-books is their flexibility. Since the display is illuminated from behind, the position of each pixel that will receive light must be fixed. Therefore, even the slightest flexibility is not allowed. E-paper has a high level of flexibility because the position of the microcapsules is not important and the size is small. E-paper has been developed to the point where it is flexible enough to be used as a pen, so it may be possible to fold it like paper and use it in the near future. Based on this flexibility, e-paper is expanding into various applications. For example, the applications are endless, from billboards that can be attached to clothes or bend, to even wearable smart devices.
However, there are also limits to electronic paper. One of them is that it cannot express a variety of colors. Some companies have come up with products that solve this problem, but there are no low-cost products for general consumers yet. Another problem that has not yet been solved is the slow screen response speed due to the direct movement of the particles. For this reason, current e-paper cannot play videos or run games. The fact that it cannot display pure white because of the presence of black and white particles and the relatively low resolution are also remaining issues. These technical limitations still need to be addressed, but the progress of e-paper has not stopped. Researchers around the world are working to overcome the limitations of e-paper by researching new materials and processes. For example, research is actively being conducted to improve color reproduction technology and reaction speed, and there is a good chance that new electronic paper that significantly improves existing problems will soon appear.
Despite the problems that e-paper has, more and more people are attracted to its advantages. As mentioned earlier, the sales volume of e-books has exceeded that of paper books on Amazon, and many companies in Korea and overseas are launching e-book readers using e-paper. Since 2007, middle schools in Maastricht, the Netherlands, have started using electronic paper as digital textbooks. On the day when electronic paper, which has the advantages of both paper and a display, replaces paper, you may be sitting on the sofa drinking your morning coffee, opening a single sheet of electronic paper newspaper and watching a video of the summit that took place yesterday. The development of electronic paper will not stop at mere technological innovation, but will bring about changes in our daily lives and the way we consume media. Through these changes, we will be able to enjoy a more convenient and richer information environment.
