From the site:
"How it works.
ZINK® stands for Zero Ink® - an amazing new way to print in full color without the need for ink cartridges or ribbons. ZINK Technology encompasses both the ZINK Paper® and the intelligence embedded in every ZINK-enabled device. ZINK enables a new category of color printing devices and paper that work as a system to print in a whole new way.
Based on advances in chemistry, engineering, physics, image science, and manufacturing, the development of ZINK has generated an IP portfolio that includes over 180 patents and patents pending. At the heart of the technology is ZINK Paper which looks like regular white photo paper before printing. Heat from a ZINK-enabled device activates the color-forming chemistry within the ZINK Paper, forming all the colors of the rainbow. The printing process is now radically simple. Just add ZINK Paper™."