E-Ink’s Electrophortic Technology
The electrophoretic display technique involves two parallel conductive plates with thickness of 10 to 100 millimeters, filling the gap with a mixture of hydrocarbon oil, any dark-colored dye, surfactants, and charging agents, and dispersing millions of one millimeter diameter titanium dioxide microcapsules into the mixture. Each microcapsule contains white particles with a positive charge and black particles with a negative charge. The application of negative electric fields causes the white particles to move to the top of the microcapsule and the black particles to hide at the bottom of the microcapsule, causing the area to appear to the viewer as a white dot. Similarly, application of the positive electric field causes black particles to migrate to the top and the white particles to move to the bottom, generating black text or a picture. The images once struck remain embedded there, until applying new voltage to change a page. This ability to stick, while ensuring low power utilization, also causes a low refresh rate, making this technology unsuitable for displaying animation or video.
Although Oliver Smithies discovered the elecrophoretic technology as early as in 1957, it was only in 1997, when the Michigan Institute of Technology spun off the MIT media lab as E Ink Corporation that the technology began to apply to electronic paper displays. E-ink that uses electrophortic technology is a big improvement on Gyricon as it bears close resemblance to ordinary paper in display and resolution. E-ink lacks the high-contrast available to backlit computer screens, making reading difficult in dim light, but have a reflective surface that allows reading in daylight situations, which is not possible with conventional laptop displays. Most e-books such as the Amazon Kindle, Barnes & Noble Nook, Sony Librie, Sony Reader, and iRex iLiad use e-ink.
Of late, Philips Research has made further advances in this technology by applying the Electronics on Plastic by a Laser Release (EPLaR) process that allows creating flexible plastic displays. This makes e-ink almost as flexible as conventional pulp-based paper. E Ink has joined hands with the Japanese company Toppan Printing to produce color filters, and thereby produce electronic pages with color displays.