Electronic Design

Build A Color Printer For The Cost Of A B&W Model

Static electricity can destroy chips, but it may also lead to cheaper and smaller color printers. Lawrence Schein, a former IBM and Xerox researcher, believes that electrostatic technology pioneered by Ben Franklin over 200 years ago could be used to create color laser printers that cost less and are up to 70% smaller than current models. "This is the biggest innovation in laser printing in many years," he says.

Harnessing static electricity for text and image reproduction is hardly new. It's already widely used in laser printers, photocopiers, and some fax machines. But by taking a nanotechnology approach to static charges, Schein and his research partner, Stanley Czarnecki of Torrey Pines Research, have created an enhanced electrostatic process that makes it possible to slash the amount of hardware that goes into a color laser printer.

Electrostatic printing works by transferring charged toner particles from a photoconductor belt to paper, where they are permanently fused to the paper by heat. In a color laser printer, a second belt accumulates and processes color images—black, cyan, magenta and yellow—one hue at a time. The extra belt significantly increases the printer's size, weight, and complexity.

Schein's goal was to decrease electrostatic adhesion. By making toner particles less sticky, it would be possible to apply all color images to a single photoconductor belt without disturbing already accumulated images. The approach promises color laser printers that aren't much more complex or costly than current black-and-white models.

To diminish toner adhesion, Schein studied electrostatic attraction theories and principles, including Gauss' law. He realized that the forces that make plastic-based toner particles stick to surfaces during printing are surprisingly strong. He eventually discovered that toner particles' rough edges form very small contact footprints.

"That creates exceptionally strong attractive forces," Schein says.

To reduce the number of contact points, Schein completely coated toner particles with 10-nm silica balls—a thousand times smaller than the toner particle themselves. The silica nanoballs effectively smooth the toner particles' edges and minimize the number of contact points.

"The result is reduced adhesion," Schein says. "The new system is simply a roller with toner on it, spaced away from the photoconductor. When the second color image comes around, the photoconductor's electric field just pulls the toner across the gap and doesn't disturb a previously developed color image."

Schein is currently consulting with Aetas Systems, a Taiwan-funded startup that's dedicated to developing new laser printing technology. Working with Schein, Aetas is developing a design for a new generation of single-belt color laser printers that are comparable in weight and complexity to today's black and white models.

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