Dot Matrix Printer Definition/Meaning:
A printer that creates each character from an array of dots
that are usually formed by transferring ink by mechanical impact. It may be a
serial printer, printing a character at a time, or a line printer.
The serial printer has a prim head containing typically 7 or 9
electromagnetically operated styluses. In a wire primer the styluses are steel
or tungsten wires that are constrained by a guide at the printing tip. The
styluses may also be short rods rigidly attached to a pivoting armature. The
head is mounted on a carriage that is moved along guides so that it travels
parallel to the paper and the position of the line to be printed. The styluses
are selectively operated to build up alphanumeric characters and other shapes
from a matrix of small dots, printed so that they almost touch. Alphanumeric
characters of data-processing quality are built up on a matrix of 7 or 9 dots
high by 4 or 5 dots wide.
These usually have voids and scalloped edges, which
can however be removed by making repealed passes of the head along the same line
but printing the dots in a slightly different place on each pass: the dots can
thus be made to overlap in both horizontal and vertical lines. More recent
designs of printers have 18 or 24 styluses and can produce characters that more
closely resemble ordinary typewritten quality. The generally available speed
range is 100-400 characters per second (cps) for print of data-processing
quality, and up to 100 cps for a higher-quality character.
A widely adopted
design for dot matrix line printers is to have a row of spring fingers that span
the line to be printed. Such printers operate at 200-600 lines per minute.
Enhancements of dot matrix printers include the ability to print in seven
colors. Ribbonless printers in which the ink is fed directly to the styluses are
also available.
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