Last week, a number of new technologies were announced at DEMO, a conference in Palm Desert, CA, where startups are unveiled. One company, called ZINK Imaging, impressed the media by offering a new way to print pictures without ink. By rethinking printing, ZINK, a spinoff of Polaroid, claims it can make ultraportable printers that can fit in a human hand or be integrated into digital cameras and cell phones.

The company's trick is to use a novel type of photo paper that changes color when heat is applied, says Steve Herchen, chief technology officer at ZINK. "It's the first new printing technology for digital printing that's come along in more than a decade," he says. There are a number of benefits that come with the new technology that aren't available with today's portable printers, he adds. At the top of his list is not worrying about running out of ink. People would still need to buy special photo paper, but the goal is to make this paper, which is expected to cost from 20 to 25 cents, ubiquitous.

Another benefit that comes out of the new printing approach, Herchen says, is technologists' ability to make the printer small enough to embed in portable gadgets. "If you look at any printer that prints with ink, you'd see that a fair amount of space is taken up by ink cartridges, ink ribbons, and the mechanisms to manage them," he says. With the ZINK printers, all of that bulk can be eliminated.

Historically, printing has been divided into several camps. Many home-office printers are inkjet, a relatively inexpensive technology that squirts ink from cartridges directly onto paper. More expensive laser printers use another approach that creates images using electrically charged colored powder, called toner. The third technology is called thermal printing. The most common type of thermal transfer printing uses a ribbon, similar to that in a typewriter, says Eric Hanson, manager of marking technology at Hewlett Packard Labs, in Palo Alto, CA. The ribbon is pressed to the paper, then heat is applied with a thermal printhead to transfer color. "Essentially, there's a color that can be vaporized from a ribbon and stick to paper that's designed for those dyes to stick to them," Hanson says. An example of this technology is found in Kodak's Easy Share Camera and Printer.

ZINK's printing technology is a first cousin of these traditional thermal printers. In fact, the company uses a thermal printhead similar to what's on the market today. "The printheads aren't unique to ZINK," says Herchen. "The technology to drive them is well-known. However, we've adapted them in a special way so that heat can be applied to ZINK media." Unlike the existing technologies that use thermal printheads to transfer color to paper, the new media has the color embedded in it, in the form of dye crystals that are clear at room temperature. The thermal printheads have been modified to selectively bring out the color in the dye crystals.