I was asked to post a quick summary for laypeople, but please feel free to ask about other related technologies or companies, since there's more out there than just these three, and EPDs are a big market being approached from a few angles.
The term E-Ink has become very much genericised for use in describing virtually all
e-paper display technologies. This is somewhat erroneous, as there are numerous e-paper technologies that are being developed, and will, with little doubt, become serious competitors with the E-Ink name as a dominant basis for future e-paper devices. Without getting into technical discussion, here's a beginner's guide to some of the big technologies around.
EPD
First, let's properly name
E-Ink's product. It is commonly referred to as an EPD, or
electrophoretic display. It is what is used in the Sony Readers, the Amazon Kindle, the Barnes and Noble Nook, and most other ebook reading devices. Currently, it's by far the most popular e-paper technology being used. In addition to E-Ink (which was acquired by PVI, a large display manufacturer), many other companies have been developing EPDs. Key innovations being sought after now are color (which at first was visually mediocre and very slow with EPDs) and flexible backplanes to replace the much more fragile traditional glass ones.
EWD
An up-and-coming e-paper technology is called EWD, or
electrowetting display. It is being developed by a few companies, the most public of them being
Liquavista. Their technology is also low-power, while also being able to produce video-rate speeds and higher white reflectance and contrast than EPDs are currently capable of. Their first product, LiquavistaBright, has been around a while but has not entered the ebook reader market (2010 may well change that). A successor to it is already being developed and is demonstrated at CES in January 2010, called LiquavistaColor.
IMOD
Qualcomm's
Mirasol displays use a technology called IMOD (
interferometric modulation) that, according to their marketing, is a form of biomimicry inspired by butterflies. They too are an actively-marketed e-paper developer, and expect to see usage in devices like ebook readers before the end of 2010. Their product, while being fundamentally different from both EWD and EPD, is capable of producing color video with relatively minimal power consumption.
When any apparent "ebook reader" display is announced, demonstrated, or promoted, many people ask if it's "e-ink". To address this without favouring E-Ink
as a company:- They all have excellent power consumption with fixed images (the exception being Liquavista, which is not a true bistable solution but what they call a quasi-stable one)
- They are all reflective displays ("less straining" for the people who find that backlighting hurts their eyes)
So in those senses, they are all
e-paper. Those consumers who enjoy the EPD screens on their current ebook readers have nothing to fear from these emerging e-paper products, and in fact should be enthusiastic that these new technologies will allow greater functionality and performance, as well as offering competition that improves not only innovation, but also market pricing.
Hope that is helpful!