E Ink's "electronic paper" is the special sauce that makes e-book readers like the Amazon Kindle possible, but it hasn't proven to be much of a meal for its venture capital backers.

The privately held company was purchased by Taiwanese display maker Prime View International on Monday for $215 million, 12 years after it emerged from a Massachusetts Institute of Technology laboratory.

peHUB notes that the decade-plus span is far from ideal for VCs (the ideal horizon is five to seven years). Even worse, VCs including Intel Capital, Motorola Ventures, Solstice Capital, the McClatchy Company, Lucent Technologies, FA Technology Ventures, and the Hearst Corporation sunk some $148.8 million into E Ink over the years, for an underwhelming 1.4 multiple.

E Ink holds more than 100 patents on its "electrophoretic" ink technology, in which electric charges are sent along a grid embedded in the paper. The charges cause tiny black and white particles to move up and down, creating text and images.

E-Ink and Prime View are already close business partners, with E-Ink providing the front part of flexible displays to Amazon and Sony. Prime View makes the back end and assembles the displays. The companies said said the deal would provide the financing and manpower needed to fuel development of color displays, slated for mass production at the end of 2010.