Xerography
Xerography was invented in 1938 by a man named Chester Carlson. Carlson is the man who patented the xerography process as well. The patent was granted for xerography in 1942, which is also known as electro-photography.
Xerography is a form of dry photocopying which is used in photo copying machines. The very first commercial machine was released by the Xerox company in 1960. Carlson was not the first to invent dry printing, but was the first to make it practical to use. Another man by the name of Georg Christoph Lichtenberg made an electric printing machine 18 years before Carlson, but it involved many steps.
Xerography involves seven steps. The first step is charging. The second step in xerography is exposure. The next steps are development, transfer, separation or detack, fixing or fusing, and the seventh and final step in xerography is cleaning. In simple terms, light is reflected from a laser to a page of white paper with black writing. Because there is a white background, light is reflected off, on to a separate plate that is electrically charged. Light does not reflect from the black lettering. Toner, which is a plastic powder, sticks to the part that was reflected and charged. Then paper passes through the machine, and the ink sticks to the paper by the process of heat. More detail about these steps can be found on Wikipedia.
The first company to use xerography in animation was Ub Iwerks in 1961. The very first film to be printed using the xerography process to eliminate the need for artists to hand ink the cels was One Hundred and One Dalmatians. The first movie that used colored xerography was The Secret of NIMH in the 1980s.
Xerography is used in recent devices such as the obvious Xerox machines, and also fax machines, and laser computer printers.