A small private company has taken a significant step in developing a technology that promises to revolutionize the printing industry, turning the printed page into a display that can be retypeset at the click of a mouse. E Ink Corp. became the first company to commercialize electronic-ink technology this year when its Immedia displays were field-tested in a Marlborough, Mass., J.C. Penney store. The displays measure 3 ft by 4 ft and have the look and feel of poster board -- with the words as sharp and bright as ink on a printed page. Yet they can be changed remotely on a moment's notice using Motorola pager technology via a Web interface. To make the Immedia sign, the ink -- made up of microcapsules of dye and pigment chips suspended in a "liquid carrier" -- is spread evenly on a transparent material, which in turn is laminated onto a conductive material. The conductive material reaches the edge of the "page," where it connects to an interface between the pager and the sign. Electrical charges sent via the pager retypeset the sign. Compared with current LCDs, electronic ink promises better readability, more design flexibility, low power usage, and lower cost of manufacture. Further, the electronic ink can be printed onto many surfaces including cloth, and therefore can be used in may more applications than current LCDs. If it develops as promised, the technology could turn up in nearly every industry from household appliances and portable electronic devices to credit cards and the ultmate goal: electronic newspapers and books that look and feel like ink on paper. John Teresko, John Sheridan, Tim Stevens, Doug Bartholomew, Patricia Panchak, Tonya Vinas, Samuel Greengard, Kristin Ohlson, and Barbara Schmitz contributed to this article.