Polaroid, the company famous for cameras that print instant pictures, unveiled an ultrasmall photo printer today at the Consumer Electronics Show in Las Vegas. The company's new handheld printers produce color photos using novel thermal-printing technology developed at Polaroid spinoff Zink Imaging and first demonstrated earlier this year. (See "Printing without Ink.") John Pollock, the vice president and general manager of digital imaging at Polaroid, says that the printers will be available to consumers by the summer, and they will be priced at less than $150.

Pollock calls the device, preliminarily dubbed the "digital instant mobile photo printer," the ultimate in mobile printing. "When you talk about most portable printers today, you're dealing with lunchbox-sized printers," he says. "What Zink allows us to do is to get ultrasmall form factors."

The printer is about the size of a deck of cards. A user who takes a picture on a cell phone or camera can wirelessly send the file to the printer using Bluetooth, a common short-range wireless technology used in cell phones, or PictBridge, a wireless technology found in a number of cameras. The result is a two-inch-by-three-inch photo printed on paper engineered by Zink.

The printing technology is similar to that of a common thermal printer, says Steve Herchen, chief technology officer at Zink. Inside the printer is a dense collection of tiny heaters--300 per square inch. Zink's paper--which looks and feels like normal photo paper--consists of a white plastic sheet covered with three thin layers of dye molecules. Initially, these molecules have an orderly crystalline structure that renders them transparent. But when heat is applied, the molecules change orientation to become an amorphous glass, reflecting either yellow, magenta, or cyan light. By precisely controlling the temperature and duration of the heat emitted by each heater, the printer can blend the three colors into any combination.

Since Zink's technology eliminates the need for printer cartridges, Herchen says, it has led to the smallest printers on the market, and it could eventually be integrated into cell phones and cameras. It would also dispense with the inconvenience of ink cartridges that unexpectedly begin to run out of ink, and which have to be replaced. "When you go to replace an ink-jet cartridge today, it's in the $40 range," Herchen says. With Zink, a person pays only by the print. Polaroid expects to sell the photo paper for $0.30 a page. "You know exactly how many prints you're paying for," Herchen says.