Inkless printers

Inkless printers use paper with colorless dye crystals embedded between the two outer layers of the paper. When the printer is turned on, heat from the drum causes the crystals to colorize at different rates and become visible. The technology was worked on by Zink Imaging and is now available (2007). Because of the way it prints, the printer can be as small as a business card, the images are waterproof, and in fact, one product slated for release by Zink Imaging is a digital camera with a printer built into it. Xerox is also working on an inkless printer which will use a special reusable paper coated with a few micrometres of UV light sensitive chemicals. The printer will use a special UV light bar which will be able to write and erase the paper. As of early 2007 this technology is still in development and the text on the printed pages can only last between 16-24 hours before fading [2].
Palaroid Company has invented an inkless printer. The principle of work is very simple; the paper is changing its color when heat is applied. So applying certain amount of heat will make the piece of paper change color to a specific one. The paper is originally white plastic that has several thin layers. The layers are micro-thin layers of different colors: yellow on top, magenta and on the very bottom cyan. When heat is applied the paper changes it color thanks to the color layers.