E Ink ("electronic ink") is a brand of electronic paper (e-paper) display technology commercialized by the E Ink Corporation, which was co-founded in 1997 by MIT undergraduates J.D. Albert & Barrett Comiskey, MIT Media Lab professor Joseph Jacobson, Jerome Rubin and Russ Wilcox.
It is currently available commercially in grayscale and color and is commonly used in mobile devices such as e-readers, and, to a lesser extent, digital signage, smartwatches, mobile phones, electronic shelf labels and architecture panels.
Origins at MIT
The notion of a low-power paper-like display had existed since the 1970s, originally conceived by researchers at Xerox PARC, but had never been realized. While a post-doctoral student at Stanford University, physicist Joseph Jacobson envisioned a multi-page book with content that could be changed at the push of a button and required little power to use.
Neil Gershenfeld brought in Jacobson to the MIT Media Lab in 1995 after hearing his ideas for an electronic book. Jacobson, in turn, recruited MIT undergrads Barrett Comiskey, a math major, and J.D. Albert, a mechanical engineering major, to create the display technology required to realize his vision.
The initial approach was to create tiny spheres which were half white and half black, and which, depending on the electric charge, would rotate such that the white side or the black side would be visible on the display. Albert and Comiskey were told this approach was impossible by most experienced chemists and materials scientists and they had trouble creating these perfectly half-white, half-black spheres; during his experiments, Albert accidentally created some all-white spheres.
Comiskey experimented with charging and encapsulating those all-white particles in microcapsules mixed in with a dark dye. The result was a system of microcapsules that could be applied to a surface and could then be charged independently to create black and white images. A first patent was filed by MIT for the microencapsulated electrophoretic display in October 1996.
The scientific paper was featured on the cover of Nature, something extremely unusual for work done by undergraduates. The advantage of the microencapsulated electrophoretic display and its potential for satisfying the practical requirements of electronic paper are summarized in the abstract of the Nature paper in these terms:
It has for many years been an ambition of researchers in display media to create a flexible low-cost system that is the electronic analogue of paper. In this context, microparticle-based displays have long intrigued researchers. Switchable contrast in such displays is achieved by the electromigration of highly scattering or absorbing microparticles (in the size range 0.1–5 μm), quite distinct from the molecular-scale properties that govern the behaviour of the more familiar liquid-crystal displays. Micro-particle-based displays possess intrinsic bistability, exhibit extremely low power d.c. field addressing and have demonstrated high contrast and reflectivity. These features, combined with a near-lambertian viewing characteristic, result in an "ink on paper" look. But such displays have to date suffered from short lifetimes and difficulty in manufacture. Here we report the synthesis of an electrophoretic ink based on the microencapsulation of an electrophoretic dispersion. The use of a microencapsulated electrophoretic medium solves the lifetime issues and permits the fabrication of a bistable electronic display solely by means of printing. This system may satisfy the practical requirements of electronic paper.
A second patent was filed by MIT for the microencapsulated electrophoretic display in March 1997.
Subsequently, Albert, Comiskey and Jacobson along with Russ Wilcox and Jerome Rubin founded the E Ink Corporation in 1997, two months prior to Albert and Comiskey's graduation from MIT.
At the E Ink Corporation, Comiskey led the development effort for E Ink's first generation of electronic ink, while Albert developed the manufacturing methods used to make electronic ink displays in high volumes. Wilcox played a variety of business roles and served as CEO from 2004-2009.
On June 1, 2009, E Ink Corp. announced an agreement to be purchased by one of its primary business partners, Prime View Int'l Co. Ltd, for US$215 million. The purchase price was re-negotiated in the latter half of 2009. E Ink was officially acquired on Dec. 24, 2009, for $450 million. The purchase by this Taiwanese company magnified the scale of production for the E Ink e-paper display, since Prime View also owned BOE Hydis Technology Co. Ltd and maintained a strategic partner relationship with Chi Mei Optoelectronics Corp. (now Chimei InnoLux Corporation, part of the Hon Hai-Foxconn Group). Foxconn is the sole ODM partner for Prime View's Netronix Inc., the supplier of E Ink panel e-readers, but the end-use products appear in various guises, e.g., as Bookeen, COOL-ER, PocketBook, etc.
The Motorola F3 was the first mobile phone to employ E Ink technology in its display to take advantage of the material's ultra-low power consumption. In addition, the Samsung Alias 2 uses this technology in its keypad in order to allow varying reader orientations.
The October 2008 limited edition North American issue of Esquire was the first magazine cover to integrate E Ink. This cover featured flashing text. It was manufactured in Shanghai and was shipped refrigerated to the United States for binding. The E ink was powered by a 90-day integrated battery supply.
In July 2015 New South Wales Road and Maritime Services installed road traffic signs using E Ink in Sydney, Australia. The installed e-paper traffic signs represent the first use of E Ink in traffic signage. Transport for London made trials of E Ink displays at bus stops to offer timetables, route maps and real-time travel information. Some Whole Foods 365 stores have employed E Ink-powered electronic shelf labels that can be adjusted and updated remotely and include additional information, such as whether a product is gluten-free. E Ink Prism was announced in January 2015 at International CES and is the internal name for E Ink’s bistable ink technology in a film that can dynamically change colors, patterns and designs with architectural products. E Ink displays can also be made flexible, just like LCDs, OLEDs and microLED. 
Commercial display products
Versions or modela of E Ink are marketed under different brand names, as explained below.
E Ink Vizplex
E Ink Vizplex is the retroactive name used to refer to the first generation of the E Ink displays. Vizplex was the internal name of E Ink's display technologies, which was announced in May 2007. E Ink originally used the term "Vizplex" as an umbrella term that included multiple generations of E Ink display technologies. For example, E Ink Pearl and E Ink Triton used the text "E Ink Vizplex" at the bottom of startup screens for those displays. However, as more generations were released, "Vizplex" became more often used to refer to specifically the first generation of the E Ink product line, in order to have a designation for the first generation to distinguish it from future generations.
E Ink Pearl
E Ink Pearl, announced in July 2010, is the second generation of E Ink Vizplex displays, a higher-contrast screen built with E Ink Pearl imaging film. The updated Amazon Kindle DX was the first device announced to use the screen, and the Kindle Keyboard, Kindle 4, and Kindle Touch also incorporate the Pearl display. Amazon still uses this display technology in the Kindle (all generations, minus the Paperwhite, Voyage, and Oasis series). Sony has also included this technology into its latest release of the Sony Reader Touch edition. This display is also used in the Nook Simple Touch, Kobo eReader Touch, Kobo Glo, Onyx Boox M90, X61S and Pocketbook Touch.
E Ink Mobius
E Ink Mobius (also known as E Ink Flex) is a modification of E Ink Pearl. It does not have one of the main disadvantages of the first two models of E Ink displays: a substrate made of very thin glass. E Ink Vizplex and E Ink Pearl have fragile screens which can be broken easily. The substrate of E Ink Mobius is made of flexible plastic, so it can resist small impacts and some flexing. Nearly A4-sized E ink Mobius devices make up the most expensive e-readers. These include Sony Digital Paper DPT-S1, Pocketbook CAD Reader Flex and Onyx Boox MAX 3.
E Ink Triton
E Ink Triton, announced in November 2010, is the third generation of E Ink Vizplex displays: a color display that is easy to read in high light. The Triton is able to display 16 shades of gray, and 4,096 colors. E Ink Triton is used in commercially available products such as the Hanvon color e-reader, JetBook Color made by ectaco and PocketBook Color Lux made by PocketBook.
E Ink Carta
E Ink Carta, announced in January 2013 at International CES, is the fourth generation of E Ink displays and features 768 by 1024 resolution on 6-inch displays, with 212 ppi pixel density. Named Carta, it is used in the Kindle Paperwhite 1st (2012) and 2nd (2013) generations and the Pocketbook Touch Lux 3 (2015).
E Ink Carta HD
E Ink Carta HD features a 1080 by 1440 resolution on a 6" screen with 300 ppi. It is used in many eReaders including the Kindle Voyage (2014), Tolino Vision 2 (2014), Kindle Paperwhite 3rd and 4th generation (2015 and 2018), Kobo Glo HD (2015), Nook Glowlight Plus (2015), Cybook Muse Frontlight, Kindle Oasis (2016), PocketBook Touch HD (2016), PocketBook Touch HD 2 (2017), and the Kobo Clara HD (2018).
E Ink Carta and Carta HD displays support Regal waveform technology, which reduces the need for page refreshes.
E Ink Kaleido
E ink Kaleido, originally announced in December 2019  as "Print Color", is the first of a new generation of color displays based on one of E Ink's greyscale displays with a color filter layer. E Ink Kaleido uses a plastic colour filter layer, unlike the glass filter layer used in the E Ink Triton family of displays. 
E Ink Spectra
E ink Spectra is a three pigment display. The display uses microcups, each of which contains three pigments. It is available for retail and electronic shelf tag labels. It is currently produced with black, white and red or black, white and yellow pigments.
Advanced Color ePaper
Advanced Color ePaper (ACeP) was announced at SID Display Week in May 2016. The display contains four pigments in each microcapsule or microcup thereby eliminating the need for a color filter overlay. The pigments used are cyan, magenta, yellow and white, enabling display of a full color gamut and up to 32,000 colors. Initially targeted at the in-store signage market, with 20-inch displays with a resolution of 1600 by 2500 pixels at 150 ppi with a two second refresh rate, it began shipping for signage purposes in late 2018 but is years away from being available for e-readers.
Comparison of E Ink displays
A comparison of a selection of E Ink displays as of June 2017
|Diagonal length or diameter (inch)||1.1||1.3||1.43||3.5||4.3||4.7||5.2||6||6.8||7.8||10.3||13.3||31.2||42|
|Resolution (horizontal × vertical)||240 × 240||256 × 256||128 × 296||360 × 600||480 × 800||540 × 960||540 × 960||1072 × 1448||1080 × 1440||1404 × 1872||1404 × 1872||1650 × 2200||1440 × 2560||2160 × 2880|
|Active area (mm)||27.96 × 27.96||23.30 × 23.30||14.46 × 33.45||45.54 × 75.90||56.16 × 93.60||58.32 × 103.68||64.53 × 114.24||90.60 × 122.40||103.68 × 138.24||118.64 × 158.18||157.25 × 209.66||202.95 × 270.60||388.80 × 691.20||642.6 × 856.8|
|Outline dimensions (mm)||31.80 × 34.60||27.10 × 28.40||18.30 × 42.70||51.54 × 86.50||62.40 × 106.40||62.1 × 115.2||69.23 × 124.59||101.80 × 138.40||119.70 × 158.50||127.60 × 173.80||165.80 × 227.70||215.50 × 287.00||402.80 × 697.20||650.0 × 872.5|
|Pixel density (pixels per inch)||218||279||225||200||216||234||213||300||260||300||226||206||94||85|
|E Ink film||Carta 1.2||Thin Pearl||Pearl||Pearl||Pearl||Carta 1.2||Carta 1.2||Carta 1.2||Carta 1.2||Carta 1.2||Carta 1.2||Carta 1.2||Pearl||Pearl|
|Refresh time (ms)||800||3200||800||450||450||480||480||450||450||450||450||450||980||-|
|Total thickness (mm)||0.53||0.4||0.607||1.18||0.912||0.682||0.68||1.01||1.84||0.78||0.65||0.65||0.805||-|
|Total weight (g)||0.72||0.4||0.87||10||12.8||6.6||12.3||30||54||37||32||68||494||1100|
|Number of levels of grey||4||2||4||16||16||16||16||16||16||16||16||16||16||16|
|Surface treatment||Hard coat||Hard coat||Hard coat||Hard coat||Hard coat||Hard coat||Hard coat||Anti-glare treatment||Anti-glare treatment||Hard coat||Anti-glare treatment||Anti-glare treatment||Hard coat||Hard coat|
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