As well as being used for in-store signage, E Ink's technology powers Sony's e-book reader, and in April, Seiko, a watchmaker, unveiled a digital watch built around an E Ink display.

ECONOMIST: REPORTS

Sony has introduced an e-book reader that uses electrophoretic materials to provide a high-resolution, high-contrast display.

ECONOMIST: REPORTS

Can Barnes and Noble or Sony really take a bite out of the e-book reader market by dethroning the iPad or the Kindle?

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He added that the shift "allows Sony to make its e-book store compatible with multiple devices and its Reader devices open to multiple sources for content".

BBC: Sony to back open e-book format

Sony's move is also seen as a response to the widely perceived success of Amazon's Kindle e-book reader - although so far the online store has declined to reveal how many devices it has sold.

BBC: Sony to back open e-book format