A descendant of the old-fashioned hand-cranked
mimeograph machine. Modern duplicators make
mono (one coloured) copies faster and cheaper than most
photocopiers when copies are made in
volume.
The duplicator first takes a
digital "snapshot" of the image with a
CCD, using a similar method to a home PC
flatbed scanner. The duplicator is now ready to make a "
master."
Special paper, similar to
wax paper is fed off of a roll and through a
thermal print head. The print head melts away the wax in the dark areas, and leaves the wax intact in the light areas. The finished
master is then wrapped around and clamped to a special
drum.
The duplicator
drum consists of several layers of metal screens wrapped around a large metal form. In the bottom of the drum is a rubber roller which transfers liquid ink from the ink nozzles to the inside of the screen.
Once the
master is made and clamped to the
drum, the
drum begins to rotate at a high speed. Sheets of
paper are fed in from one end, pass rapidly between the
drum and a rubber
pressure roller, and are ejected from the other end into a collection bin to dry. Each time the
drum rotates, one copy is made.
Duplicators are highly
efficient when printing in large volumes, but costly and
wasteful for small volumes. Each time you want to make a copy of a different
original, the old
master is ejected and a fresh one made.