In this blog post, we will look at the technological potential of electronic paper to replace paper, focusing on its principles, advantages, and potential applications.
There is a saying that goes, “You can live a day without food, but you can’t live a day without electronics.” Electronics have thus become deeply ingrained in modern life. In particular, the media we watch and read, such as TVs, smartphones, and PMPs, are all made with IT technology. Today, people’s lives are closely connected through real-time information, video content, and the digitization of work, which is driving a surge in demand for display devices and increasing interest in new display technologies. The only media that have not yet been digitized and remain in an analog form are newspapers delivered every morning and books on bookshelves. However, even these paper-based media are seeing a wave of digitization. At the center of this change is electronic paper, which is attracting attention as a next-generation display technology that can effectively replace paper.
The basic principle of electronic paper is simple. Electronic paper is a structure in which small capsules called microcapsules are continuously arranged between the upper and lower metal plates, and a fine electrical circuit flows underneath. The microcapsules are filled with a colloidal liquid, and charged ink particles are contained in the liquid. Black ink particles have a positive charge, while white ink particles have a negative charge. By using the property that these charges attract each other when they are of different polarities and repel each other when they are of the same polarity, it is easy to display information on electronic paper.
If you look deeper into the principle of electronic paper, its innovation becomes clear. When a positive voltage is applied to the electrical circuit under the electronic paper, the white capsule with a negative charge is attracted to the direction of the applied voltage, and the black capsule with a positive charge moves in the opposite direction, allowing you to see the black ink. On the contrary, applying a negative voltage causes white ink to appear. In this way, electronic paper displays text and images like paper. Unlike conventional displays that emit light to ensure the visibility of information, electronic paper displays express information through differences in ink color, so the eyes are comfortable even when reading for a long time, and power consumption is significantly lower.
This type of electronic paper has three distinctive advantages: bistability, reflexivity, and flexibility. First, bistability means that it has two stable states. The liquid in the microcapsules is highly adhesive, so once the ink is moved, it does not move easily until it is re-energized. Therefore, even when each capsule appears black or white, it can remain stable with the power off, allowing information to be retained for a long time. This is excellent for low-power displays such as existing e-books and e-paper billboards.
In addition, e-paper is a reflective display that displays information by reflecting ambient light rather than emitting light itself. Thanks to this, the display is easy to read with a natural brightness that matches the ambient brightness, and it is particularly easy to see in sunlight, so it consumes less power and is environmentally friendly. Finally, the flexibility of e-paper allows the display to be thin and bendable, making it suitable for various applications such as smartphones, e-books, and fashion wearables.
The innovative changes that e-paper technology will bring are not limited to e-books. Recently, there has been active development of smart watches, smart cards, and traffic information displays using the bistability and reflective properties of e-paper. For example, a watch using e-paper can display the time for several days on a single charge and can display personalized information on the watch screen as needed. The introduction of e-paper is also being considered for industrial applications such as RFID tags in logistics and libraries. E-paper tags display information about products or inventory status and are efficient because they use power only when updates are needed.
Another example is electronic price tags and smart name tags that use the bistability of e-paper. In large supermarkets and retail stores, e-paper displays can be used as product price tags, which can be easily updated and retain existing information even when the power is cut, saving power. This makes e-paper an environmentally friendly and economical choice that can reduce operating costs while protecting the environment.
E-paper is not yet able to completely replace conventional paper in all aspects. E-paper is somewhat slow in its response speed, which limits its use in fast-moving video or graphics, and its readability may be poor in dark places with insufficient ambient lighting. Initially, information could only be expressed in black and white, but the recent emergence of color e-paper technology is expected to be used in a variety of areas, including advertising, education, and publishing.
As such, e-paper, which has the advantages of paper and display at the same time, has a great potential to be applied in a wider range of fields in the future. With the huge amount of paper used worldwide every year and the serious impact it has on the natural environment, the spread of e-paper can be an option for practicing sustainability. As a result, e-paper is emerging as an important alternative in a new era where IT technology and environmental protection are in harmony.
