This article explains the basics of electronic paper technology and electrophoretic displays (EPD). The EPD was created by eInk Corporation in the late 1990s.
EPDs relay on electrophoresis, which is the motion of dispersed particles in a fluid under the influence of an electric field.
Electronic ink is made of millions of microcapsules with pigment particles floating in clear fluid. The ink layer is placed between two electrode layers. The particles are charged: white - positively, black - negatively. When a voltage is applied, particles move based on their charges. The top electrode is transparent. When black particles go to the top of the capsule, that spot on the display looks black. EPDs use thin-film transistor technology. This technology controls the voltage for different parts of the display to create an image. Special software was designed to control voltage sequences using algorithms called waveforms. When the voltage is removed, the particles stay in their positions. EPDs can display static images without using electricity, making them very energy efficient.
Electronic paper displays are known for their ultra-low power consumption. EPDs only draw power when the content changes (and the particles must be rearranged). Unlike LCD screens, EPDs don't need constant refreshing and can last weeks on one battery charge.
Electronic paper looks like ink on regular paper, using the same pigments as traditional printing. It also aims to give the reader the same readability experience. EPDs are reflective display. They don't emit any light, but reflect ambient light, like paper. The text can be read in direct sunlight and at a wide viewing angle. EPDs also cause less eyestrain, because they don't need to be back-illuminated.
Electronic paper is widely known for its use in e-book readers. However, this technology has also been used in other industries. Especially those where low energy consumption and high readability play a vital role.
Here are some examples:
-
digital signage
-
transport information system
-
menu boards
-
directional signs
-
shelf labels
