A device that converts computer output into printed images. Following is an overview of the various technologies. For more details, look up the individual entries.
General Categories
Following are the broad categories of printers.
Serial Printers (Character Printers)
Serial printers print one character at a time moving across the paper. Electrosensitive, direct thermal, older daisy wheel and even inkjet printers could be cataloged in this group; however, the primary desktop serial printer is the serial dot matrix printer, with speeds ranging from 200 to 400 cps, which is about 90 to 180 lines per minute (lpm).
Line Printers
Line printers print a line at a time from approximately 400 to 2,000 lpm and are commonly found in datacenters and industrial environments. Earlier technologies included drum, chain, train and dot band matrix technologies. The surviving technologies use band and line matrix mechanisms.
Page Printers
Page printers print a page at a time from four to more than 800 ppm. Laser, LED, solid ink and electron beam imaging printers fall into this category. All of these printers adhere toner or ink onto a drum which is transferred to the entire page in one cycle for black and white and multiple cycles for color.
Impact Printers
Impact printers were the first type of printer on the market. Like a typewriter, a "hammer" presses the ink onto the paper.
Serial Dot Matrix
A desktop printer that uses a moving printhead of wire hammers. It forms characters and graphics by impacting a ribbon and transferring dots of ink onto the paper. See
dot matrix printer.
Line Matrix
A type of line printer that uses an oscillating row of print hammers. The hammers form characters and graphics by impacting a ribbon and transferring dots of ink onto the paper. See
line matrix printer.
Band (Line Character)
A type of line printer that uses a fixed set of characters attached to a continuously revolving metal band. A set of hammers (one for each column) hit the paper, pushing it into the ribbon and against the character image on the band. See
band printer.
Earlier Impact Technologies
Impact printers were developed for the first computers, and several earlier technologies have gone by the wayside.
Chain, train and drum printers were precursors to band printers. They all used actual shaped characters, or type slugs, to print a fixed size and style of letter and digit. Daisy wheel printers were desktop impact printers used in the 1970s and 1980s. Dot band matrix printers used a combination of band printer and dot matrix methods. See
chain printer,
train printer,
drum printer,
daisy wheel and
dot band matrix printer.
Non-Impact Printers
These are common types of printers used in the home and office today.
Laser & LED
Laser printers and LED printers employ the electrophotographic method used in copy machines. Both technologies are available from small desktop units to high-speed digital printing presses, ranging in speed from four to more than 700 ppm, and color units from three to 75 ppm. See
laser printer,
LED printer and
electrophotographic.
Inkjet
Inkjets have become the most popular form of desktop personal printer, and all units print in color. Inkjets propel droplets of ink directly onto the paper. See
inkjet printer.
IRIS
IRIS printers use inkjet technology, but are in a class by themselves. They achieve a perceived 1,800 dpi resolution and can print on fabric as well as paper. See
IRIS printer.
Solid Ink
Solid ink printers use sticks of wax ink that are melted into a liquid. The ink is directed onto a drum, similar to a laser printer, and then transferred onto the paper to produce high-quality output. See
solid ink printer.
Electron Beam Imaging
A technology somewhat similar to a laser printer, except that electricity is used to create the image instead of light. This evolved from ion deposition and is used in very high-speed page printers exceeding 800 ppm. See
electron beam imaging.
Thermal Wax Transfer & Dye Sublimation
Dots of ink or dye are transferred from a ribbon onto paper by passing the ribbon and the paper across a line of heating elements. Thermal wax is used for barcode and other types of labels as well as medium-resolution graphics. Dye sublimation is used for photorealistic color output. See
thermal wax transfer printer and
dye sublimation printer.
Electrosensitive
A dot matrix printhead charges dots on aluminum-coated silver paper, usually in a serial fashion. The charge removes the coating, leaving a black image. See
electrosensitive printer.
Direct Thermal
Used in barcode and other specialty printers as well as in earlier fax machines, dots are burned onto a type of coated paper that darkens when heat is applied to it. See
direct thermal printer.
Electrostatic
Dots are charged onto a coated paper, typically a line at a time. A toner is attracted to the paper and made permanent by pressure or heat. See
electrostatic plotter.