The first eInk prototypes were under development in the early nineties, but it’s taken around twenty years for its revolution of print to really begin.
EInk, for those unsure, is the technology used in eBook readers, such as Amazon’s Kindle and the Sony eReader. Essentially, eInk offers a suitable alternative to reading on paper, as it replicates the visual aesthetics of printed paper in a screen, but without use of a backlight.
Electronic ink works by utilising millions of microcapsules, each barely wider than a human hair. Within each capsule there are thousands of both negatively charged black pigment particles and positively charged white pigment particles. These particles are naturally suspended with a clear fluid, until an electric field is applied. Upon application of the field, depending on its positive or negative charge, the particles are forced up or down. The pigment that moves upward then becomes visible to the reader.
Perhaps it is easier to consider a room with a glass ceiling. Imagine that there are lots of balloons held in a net in mid-air. In the net there are two types of balloons; some black and some white. The black balloons are filled with helium, but the white balloons have just been blown up normally. Upon their release, the black balloons will rise, and the white ones will fall, separating the colours. If you were then to look down through the glass ceiling, you would only see the black balloons.
EInk works in a similar way, except as the particles are charged, both white and black can be made to rise to the “ceiling” of the capsule depending on the charge of the electric field that is applied. These thousands of coloured particles once positioned at the top of the capsule, appear to a reader as a black or white spot.
The success of electronic ink lies largely in it not necessitating the use of a backlight, as with a normal screen. This avoids eye strain, and enables users to enjoy reading using just natural light without it becoming hard to read. Indeed, the better lit the environment, the easier it is to read from an eInk device, such as in bright sunlight, where using an LCD screen would be near to impossible.
Also adding to the popularity of eInk is its environmentally friendly image. Not only does the use of a screen mean that not as much paper need be produced, but the capsules themselves only require a very small amount of power to change the colour they are displaying. This results in an eInk display using very little power, lasting for months at a time off only one charge of a small battery (the kindle battery is 3.7 V, with a capacity of 1530 mAh).
The most recent development in electronic ink technology has been the introduction of colour. This has been achieved by embedding an RGBW filter on top of the layer of microcapsules. When the white particles are forced to the top of the capsules, they reflect ambient light back through the filters, allowing it to appear as colour to a reader.
It’s possible to apply electronic ink to a wide range of uses, including advertising, keypads, watches, phones, wireless devices and more. The versatility of eInk and its relative youth means that it’s certainly one to watch to for the coming decade as it becomes more and more widely used.