How can e-paper replace and further the role of paper in the modern world?

E-paper has been applied to various fields such as e-books and e-paper watches due to its bistable, reflective, and flexible properties. Although there are disadvantages such as response speed and readability in the dark, e-paper is expected to be a promising technology to replace paper when considering environmental protection and user convenience.

 

As the joke goes, “You can live a day without food, but you can’t live a day without electronics.” As such, electronics have permeated modern life. In particular, the media we watch and read, such as TVs, smartphones, and PMPs, have all been created with IT technology. The only media that have not yet been digitized and remain analog are the newspaper delivered in the morning and the books on our bookshelves. But paper media is also going digital. E-paper is the next generation of display technology that promises to effectively replace paper.
The principle of e-paper is simple. E-paper consists of a series of tiny capsules called microcapsules arranged between metal plates on top and bottom, with tiny electrical circuits running underneath. The microcapsules are filled with a colloidal liquid and contain charged ink microparticles. The black ink particles are positively charged and the white ink particles are negatively charged. These charges attract opposite poles and repel like poles, making it easy to display information on electronic paper.
If you apply a positive voltage to the electrical circuit below the paper, the negatively charged white capsules will be attracted to the direction of the voltage, while the positively charged black capsules will move to the other side, revealing black ink. Conversely, if you apply a negative voltage, you’ll see white ink.
Unlike conventional displays, which control the amount of light they emit to show information in terms of relative light intensity, e-paper uses a unique method of displaying information using actual ink. This gives e-paper several distinct advantages. The main characteristics of e-paper can be summarized as bistable, reflective, and flexible.
First, bistability means having two stable states. The liquid in the microcapsules is highly tacky, so once the ink has moved, it doesn’t move easily until the voltage is applied again. So even when each capsule appears black or white, it remains in a stable state, so the information remains intact when the power is turned off. This allows the information to be retained for long periods of time without power.
Second, it is reflexive, which means that it glows by reflecting ambient light rather than being self-luminous. This characteristic makes e-paper very similar to paper, which means it’s easier on the eyes over time and uses less power.
Third, flexibility is something that is not easily achieved in displays. E-paper uses metal foil plates instead of glass plates, making it easier to bend the electrical circuits. In addition, the microcapsules used in e-paper can be made as small as 30 micrometers, which is thinner than a human hair. Thanks to these tiny particles, e-paper has the same flexibility as real paper.
With all these advantages, e-paper also has its drawbacks. Because the ink travels directly to display information, it’s slow to respond, so you can’t use it to play videos, play games, or do anything that requires a fast response time. Also, because of the reflective display, you can’t read anything in the dark. Initially, e-paper had the disadvantage of only being able to display black and white, but nowadays, e-paper that can display color has been developed and is on its way to production.
Despite these drawbacks, e-paper has many applications due to its unique characteristics. The most popular example is e-books. E-paper is most often used to make e-books, and e-books are perfect for this because the information doesn’t need to change rapidly, as you slowly flip through the pages. Also, since books are meant to be looked at for long periods of time, e-paper is easier on the eyes, so you can read e-books for longer periods of time without experiencing the same fatigue as when looking at a monitor.
Another important application that takes advantage of the flexibility of e-paper is e-paper watches. By rolling e-paper into a ball and wearing it on the wrist, e-paper watches are expected to take advantage of low power to not only display the time for several hours on a single charge, but also to provide additional media functions such as reading novels or viewing photos by unfolding it.
In addition, by applying the bistability of e-paper to a removable disk, the remaining capacity can be displayed on the outside of the disk while it is powered, and the remaining capacity can be displayed even when the power is cut off. This makes it possible to create removable disks that can be plugged in and still show the remaining capacity.
E-paper is expected to be applied to many more fields in the future, as it combines the advantages of paper, such as less eye strain and flexibility, with the convenience of electronics, such as the ability to easily change information. As long as nostalgia for traditional books and newspapers remains, it will be difficult for e-paper to completely replace the current paper, but with 140 million trees worth of paper being consumed in Korea every year, the spread of e-paper will be a choice that considers the convenience of users and the environment.