Xerox scientists discuss groundbreaking technologies engineered to make great colour prints

Producing great colour prints is all about ultra-fine precision, and Xerox Corporation scientists are applying their expertise in precision imaging across a range of products, according to presentations that were done at NIP20: The International Conference on Digital Printing Technologies, that took place in Salt Lake City from 31 October to 5 November 2004.

In separate presentations, Rick Lux and Huoy-Jen Yuh from Xerox`s Webster, New York, research and development complex, and James D Padgett and Rodney Hill from Xerox`s office products research and manufacturing facility in Wilsonville, Oregon, discussed engineering aimed at even higher image quality in the company`s colour digital presses and printers.

Their papers were two of the 15 technical papers Xerox presented at the conference. In addition, its researchers shared their knowledge in six tutorials, and the company was a corporate sponsor of the event. The annual NIP meeting, jointly sponsored by the Society for Imaging Science and Technology and the Imaging Society of Japan, was the pre-eminent forum for discussions of advances and directions in non-impact and digital printing technologies. This was its 20th year.

Lux leads Xerox`s Production Xerographic Competency Centre, of which Yuh is a member. Their paper revealed how the company overcame key technical challenges in the development of Xerox`s patented Image-on-Image marking technology.

The company`s first product employing IOI technology, the 100-page-per-minute Xerox iGen3T Digital Production Press, was so innovative that Xerox has received or applied for more than 425 patents associated with unique areas of the machine.

In their presentation, Lux and Yuh provided a behind-the-scenes look at Xerox`s new high-speed marking technology, which was developed to deliver exceptional colour images and high-precision registration at reduced costs and on a wide range of media. The centrepiece of this third-generation digital colour printing system is the Recharge, Expose and Develop (REaD) IOI process, the first that can build a four-colour image on the photoreceptor in a single pass, then transfer the image to paper in a single step.

Single-step transfer eliminates opportunities for mis-registration, according to Lux and Yuh, and it results in image registration accuracy better than 40 microns, producing print quality close to - and in some cases better than - offset. (There are 25 400 microns in an inch, and the period at the end of this sentence is about 600 microns wide.) Single-step transfer also ensures consistent image quality job-to-job and machine-to-machine.

In Wilsonville, Xerox scientists are working to increase performance of office products by developing printheads with higher jetting frequencies, configurations to pack more jets into a given space, and ways to decrease drop mass.

One challenge: all colours are built up from just four colours of ink - yellow, cyan, magenta and black. To get green in a printed image, for example, a cyan drop must be deposited on top of a yellow drop. But as ink drops get smaller, they solidify faster, and the second drop tends to slide off to one side, increasing colour-to-colour dot position error. It`s a problem called "dot position amplification".

Padgett and Hill have found that while it seems counterintuitive, intentionally mis-registering the colours could solve the problem, according to a paper on the technique prepared for the NIP conference. Their technique has been used on the Phaser 8400 Color Printer, a 24ppm solid ink printer that`s priced at less than $1 000. Introduced in early 2004, the printer has received accolades for its outstanding print quality.

Other Xerox papers at the conference covered topics ranging from GlossMark images, a technique for authenticating documents, to use of modern control theory to automate document production processes. Also included was research on characterisation of surface properties of xerographic developers done in collaboration with the University of Montreal and research on half toning done with Purdue University.

Xerox Corporation is a $15.7 billion technology and services enterprise that operates research and technology centres in the US, Canada and Europe that conduct work in colour science, computing, digital imaging, work practices, electromechanical systems, novel materials and other disciplines connected to Xerox`s expertise in printing and document management. The company consistently builds its inventions into business by embedding them in superior Xerox products and solutions, using them as the foundation of new businesses, or licensing or selling them to other entities. For more information, visit www.xerox.com/innovation.