An e-paper display, also called electronic paper display, is a type of power-efficient electronic display that resembles paper. Unlike LCDs or OLED and AMOLED displays, electronic paper screens reflect light rather than emitting light, just like regular paper.
The images are produced using e-ink, and no electricity is needed to keep them on the screen, therefore drastically reducing the screen's power consumption. The e-ink screen is formed of millions of microscopic ink capsules filled with a suspended clear fluid (liquid polymer), placed between two sheets of thin film with electrodes on both sides. Typically, these capsules contain a negatively charged black pigment and a positively charged white pigment, hence producing grayscale images. There are also e-ink displays that contain colored pigments, but the most common ones work with black and white pigments only. Depending on the electric charge applied to the electrodes, the particles will move in the capsule, generating black or white pixels. With millions of capsules, high-resolution images appear on the screen.
If no electric charge is applied, the image stays the same. Keeping an e-paper display on without changing the image requires very little energy. These types of displays are known as bistable because they use two types of electric charges to generate images. This bistable technology, highly power-efficient, makes e-paper displays extremely versatile and well-suited for various types of industries. It is not surprising that some smartphone manufacturers have started using secondary e-paper screens for their devices. There are also many wearable devices and smart-home devices with e-ink displays. Still, the most popular industry for electronic paper manufacturers is the e-book reader industry, which employs almost exclusively e-ink displays. In addition to low power consumption, these displays are also lightweight, have extremely wide viewing angles, and put less strain on the eyes.