Spectrophotometer-based system enables self-calibration by printers

APRIL 17--Scientists at Xerox Corp. (Webster, NY; www.xerox.com) have patented an ultrafast, low-cost spectrophotometer that's expected to streamline and simplify color printing. This spectrophotometer also has potential uses in other fields that demand precise color matching, including fabrics, paint, wallpaper, plastics, and interior design, according to L.K. Mestha, Xerox principal scientist.

Xerox's invention is claimed as a breakthrough in both measurement and control. Scientists designed a spectrophotometer that costs less than one-sixth the price of current models. It will be embedded inside a digital printer to make full color measurements on each passing page in just milliseconds. During that time, the spectrophotometer shines light of different colors from several LEDs onto tiny color patches on paper moving at the speed of the printer, analyzes the reflected light, and determines its color makeup "on the fly."

With Xerox-proprietary control algorithms, the digital printer can compare the color of each patch to the color in the original image. While the printer is running, the system can make minute adjustments to all the pixels in the image at the machine printing speed.

"When machines can regulate themselves, they won't have to be designed with micron-level precision, and parts will last longer. They will be able to tolerate differences in materials and operating environments, and the result will be fewer service calls. Printing professionals will be able to minimize prepress work and operator interventions, yet deliver more saleable prints," Mestha says.

The technology, in the research labs now, is expected to show up in stages in next-generation digital color printers within two years. It is also available for licensing.