Топик По Английскому Языку (Воронов Р. И.) / DIGITAL PRINTING SYSTEMS

DIGITAL PRINTING SYSTEMS
Computer-to-Print (EP) Systems
Most plateless printers can be adapted to accept digital files and become computer-to-print digital printing
systems. They use electrophotographic photoconductor, ink-jet, ion or electron charge deposition, magnetography,
thermal transfer, thermal dye sublimation and electro-coagulation technologies.
Electrophotography
In 1993, two new systems were introduced, one using liquid toner EP photoconductor technology on a sheetfed
offset press design; the other using dry toner EP technology on a web press design.
These systems are developing markets for short-run color, on-demand and variable information printing. Other
printing systems using EP engines are in use. One is a press design like the first two, and the others are
clusters of EP color copier engines.
Ink-jet systems
They use jets of ink droplets driven by digital signals to print the same or variable information directly on
paper without a press-like device.
The first plateless digital printing system was ink-jet introduced in 1970. Two types of ink-jet systems are in use:
(1) continuous jets and (2) drop-on-demand.
(1) Continuous jets are used for digital color proofing, color printers and variable information on-press
color printing systems at speeds up to 220 feet/minute.
(2) Drop-on-demand ink-jets are divided into Bubblejet and Solid Ink/Phase Change digital printing systems.
Ink-jet systems are gaining in use, especially since new inks have been developed with light- and water-fastness
properties.
Ion or electron charge deposition
It is imaged by passing digital data through an electron cartridge that generates negative charges which produce a charge image on a heated dielectric drum. The visible image is created with a magnetic toner which is transferred to the substrate by cold fusion.
Magnetography
It is similar to electron deposition except that a magnetic drum, a magnetic charge and special magnetic toners
are used to produce the printed images.
Thermal transfer printers use digital data to drive thermal print heads in press-like machines that melt spots of
dry thermoplastic ink on a donor ink ribbon and transfer them to a receiver to produce color labels, logos, wiring
diagrams, bar codes and other similar products.
Thermal dye sublimation printers are like thermal transfer printers except the inks on the donor ribbons are
replaced by sublimable dyes. The thermal head converts the dyes to gas spots that condense on the receiver.
The printers are used for digital color proofing and color printing.
Electro-coagulation printing is a unique digital printing technology. It uses a pigmented water-base ink sprayed
on a release coating on a metallic press cylinder. The image is produced by a digital file-controlled print head
that uses the cylinder as a positive electrode to coagulate the ink imagewise on the release coating.
This transfers the coagulated ink image to the paper in printing.