use digital printing technology to reproduce their work for a number of
purposes. Most of us own and rely on one or more digital printing output
devices to help us conduct our business and produce our work. Illustrators who exclusively
work digitally are totally reliant on digital printers to help proof work in
preparation for offset printing or display it in non-digital settings.
past few decades several different types of printers has been used to reproduce
digital work. Some of these device types have become all but obsolete due to
technological advancements in digital printers, which have become quite
sophisticated in quality and economically efficient.
digital were based on impact technology. These printers contain an appliance
that comes into physical contact with the paper surface in order to transfer
toner to create an image. The two main types of impact printers are character
printers and dot matrix printers.
Character printers are basically computerized
typewriters that print nothing but fixed characters. They have a ball or series
of bars with actual raised letters and numbers on the surface. To print a
letter is struck against an ink ribbon, transferring the character's image to
the paper. The characters are finite and cannot be altered.
|Inpact character printhead.|
|Impact character print sample.|
to as a pin printer, and precursor to inkjet and laser printers, dot
matrix printers use print heads to strike an ink ribbon to place hundreds to
thousands of little dots directly on the paper to form text or images. The
matrix field allowed computer manipulated imagery and type to be combined and
customized. Dot matrix printers, because of their low quality prints, have been
replaced by inkjet and laser printers.
|Dot matrix printhead.|
|Dot matrix print sample.|
As the name
suggests, non-impact printers do not touch the paper when creating an image. Both
wet and dry toner technology printers are represented in this category, which
includes inkjet, laser, thermal wax, dye sublimation, solid ink, bubble jet, piezoelectric,
and thermal autochrome printers.
printers produce prints by spraying liquid ink onto paper. Inkjet
printers can produce resolutions as fine as 600 dpi or more rather
inexpensively. The print head has several tiny nozzles, called jets that spray
ink drops onto the paper as it moves past it to produce characters and images. Because
the ink is liquid, prints require time to dry for the ink to cure properly. Most
inkjet printers contain cyan, magenta, yellow, and black inks, consistent with CMYK
4-color process printing. The more sophisticated units use as many as eight
color cartridges with red, green, blue, matt black, and gloss optimizer along
with the CMYK inks. These high-level inkjet printers can render gallery quality
digital images on special paper stocks,
|Inkjet 4-color printhead.|
|Inkjet dot pattern nagnified.|
A thermal bubble
jet printer differs from a conventional inkjet printer in the way the droplets
of ink are formed and distributed on the paper. In a standard bubble jet
printer, tiny resistors produce heat, which vaporizes the ink into bubbles.
The expansion of the liquid from the heat causes a bubble that pops or
collapses causing a vacuum to be created, which forces ink into the print head
from the cartridge to be ejected onto the paper surface. Bubble jet print head have
300 ink nozzles. High-end units have 600 nozzles, all which can dispense ink
|Bubble jet printhead dispensing ink.|
|Bubble jet print dot pattern magnified.|
, piezoelectric technology uses piezo crystal dyes. These
dyes are located at the back of the ink reservoir of each nozzle. The
crystal receives an electric charge that causes them to vibrate. When they
vibrate in the nozzle they act like a piston in an engine, alternatively
pulling ink into the nozzle from the reservoir and then dispensing it to a receiving surface. Piezoelectric printing is most commonly used for digital printing on fabrics.
|Piezoelectric dot pattern magnified.|
printers, also called laserjet printers, were developed as devices that adapted
photocopier technology for computer generated digital output. Using static
electricity and heat, laser printers differ from inkjet printers in that the toner
or ink in a laser printer is dry, whereas in an inkjet printer the ink is wet.
More commonly used for high volume output, most laser printers are monochrome,
although there are also color laser printers that contain 4-color CMYK insets
for the production of full-color prints. To print, a laser printer places an
electrical charge on a selenium drum. The charged areas attract ink, which is
then transferred to the paper surface. Most laser printers print at a
resolution of 600 dpi
however high-end models can produce resolutions as fine as 2400 dpi
|Laserjet dot pattern magnified.|
used for solid ink printers is in the form of sticks of wax-like ink
similar to hard crayons. This heat based process melts the ink as it is applied
to the paper. As the ink cools it then hardens in place. Unfortunately prints
produced using solid ink are susceptible to damage by heat such as would occur
in lamination. Solid ink printing can be applied to many different types of
media and substrates.
|Solid ink printhead and ink bar.|
|Solid ink dot pattern magnified. The American Institute for Conservation.|
colors in dye sublimation printers is supplied by rolls of red, blue, yellow
and gray colored cellophane film panels that are alternatively sectioned
together end to end. The 4-color CMYK version contains cellophane film coated
with solid cyan, magenta, yellow and black dyes corresponding to four basic
color printing. The film is heated at various temperatures, according to the
amount needed to reproduce a particular image. The heated dyes melt and permeate
the surface of the paper, then they solidify to form a print. Dye sublimation
printers apply each color individually as its own layer until the image is
completed. The dyes actually permeate and stain the paper to generate an image.
|Dye sublimation printhead with color ink ribbon.|
|Dye sublimation ink pattern magnified. The American Institute for Conservation.|
Wax Transfer Printers
A hybrid of
dye sublimation and solid ink technologies, thermal wax printers use a solid
form of ink applied to a ribbon with alternating 4 color CMYK process color
bands. Tiny heated pins contact the toner ribbon as it passes to produce an
impression on the paper surface. The heat causes the wax to melt and adhere to
the paper, where it hardens in place.
|Thermal wax transfer print head.|
|Thermal wax transfer ink pattern magnified. The American Institute for |
autochrome printers operate in a parallel way to photographic printers. The
color is contained within the autochrome paper and acts as a receptor for a
heat source, instead of a light source, that brings forth the color. The paper
contains three color layers--cyan, magenta and yellow. Color density within the
print is controlled by a varying amount of heat that is applied. in the paper,
and each layer is activated by the application of a specific amount of heat.
The print head applies each color individually by passing over the paper for
each separate color until the image is complete.
|Thermal autochrome print head.|
|Thermal autochrome dot pattern magnified. Image Permanence Institute.|
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