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The main hardcopy output devices are printers and plotters. A printer can
print characters, symbols, and sometimes graphics on paper. Printers are
categorized according to whether or not the image produced is formed by
physical contact of the print mechanism with the paper. Impact printers make
contact; nonimpact printers do not.
Impact printers usually form images by pressing an inked ribbon against
the paper with a hammerlike mechanism. A letter-quality printer, like a
typewriter, presses fully formed characters against the ribbon. A dot-matrix
printer uses separate pinlike hammers to form characters out of dot patterns.
Letter-quality printers produce higher quality images than dot-matrix printers
do and are generally used for business letters, important memos, and reports.
However, letter-quality printers are slower and noisier than dot-matrix printers,
and they cannot produce graphics. Common types of impact letter-quality
printers are the daisy wheel printer, the thimble printer, and the ball printer.
Dot-matrix printers, because they do not print fully formed characters, are
more flexible and can be used to print graphics in black or in colors.
The high-volume output requirements of most large computer installations
cannot be satisfied by dot-matrix or letter-quality printers. Large computer
systems often use special high-speed printers, called line printers, because they
print a whole line at a time. Three common types of line printers are drum
printers, band or belt printers, and chain printers.
The main categories of nonimpact printers are ink-jet printers, thermal
printers, and laser printers. These printers make much less noise than impact
printers, but they cannot be used to generate carbon copies. Ink jet printers,
which are about as fast as dot-matrix printers, form images with tiny droplets of
ink fired through a plate with holes drilled in it. Color ink-jet printers are used to
produce graphics; however, ink jets can get clogged, and the image quality is not
considered to be as good as that produced by plotters.
Thermal printers use heat to produce an image on specially treated paper.
They are very quiet; however, they are slow and the special paper is expensive.
Laser printers are nonmechanical, nonimpact printers. Because the process
has no print heads that move or print hammers that fire, the result is high speed
and quiet operation. Laser printers work somewhat like photocopying
machines. They use laser beams to transfer images to sensitive paper that is
then coated with toner — the toner sticks to the spots sensitized by the laser.
Laser printers print a page at a time and can produce very high quality images,
so they are often used for graphics. Since their prices have fallen, small laser
printers are now within reach of users wanting a high-quality desktop printer.
They are frequently used in desktop publishing, which uses microcomputers,
special software packages, and laser printers to produce material ready to be
published. However, the small, affordable desktop laser printers do not yet
produce color.
A plotter is most often used for producing graphics because it can output
free-form drawings on paper in color.
The main hardcopy output devices are printers and plotters. A printer can print characters, symbols, and sometimes graphics on paper. Printers are categorized according to whether or not the image produced is formed by physical contact of the print mechanism with the paper. Impact printers make contact; nonimpact printers do not. Impact printers usually form images by pressing an inked ribbon against the paper with a hammerlike mechanism. A letter-quality printer, like a typewriter, presses fully formed characters against the ribbon. A dot-matrix printer uses separate pinlike hammers to form characters out of dot patterns. Letter-quality printers produce higher quality images than dot-matrix printers do and are generally used for business letters, important memos, and reports. However, letter-quality printers are slower and noisier than dot-matrix printers, and they cannot produce graphics. Common types of impact letter-quality printers are the daisy wheel printer, the thimble printer, and the ball printer. Dot-matrix printers, because they do not print fully formed characters, are more flexible and can be used to print graphics in black or in colors. The high-volume output requirements of most large computer installations cannot be satisfied by dot-matrix or letter-quality printers. Large computer systems often use special high-speed printers, called line printers, because they print a whole line at a time. Three common types of line printers are drum printers, band or belt printers, and chain printers. The main categories of nonimpact printers are ink-jet printers, thermal printers, and laser printers. These printers make much less noise than impact printers, but they cannot be used to generate carbon copies. Ink jet printers, which are about as fast as dot-matrix printers, form images with tiny droplets of ink fired through a plate with holes drilled in it. Color ink-jet printers are used to produce graphics; however, ink jets can get clogged, and the image quality is not considered to be as good as that produced by plotters. Thermal printers use heat to produce an image on specially treated paper. They are very quiet; however, they are slow and the special paper is expensive. Laser printers are nonmechanical, nonimpact printers. Because the process has no print heads that move or print hammers that fire, the result is high speed and quiet operation. Laser printers work somewhat like photocopying machines. They use laser beams to transfer images to sensitive paper that is then coated with toner — the toner sticks to the spots sensitized by the laser. Laser printers print a page at a time and can produce very high quality images, so they are often used for graphics. Since their prices have fallen, small laser printers are now within reach of users wanting a high-quality desktop printer. They are frequently used in desktop publishing, which uses microcomputers, special software packages, and laser printers to produce material ready to be published. However, the small, affordable desktop laser printers do not yet produce color. A plotter is most often used for producing graphics because it can output free-form drawings on paper in color.
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