3.7. Information display devices

Printers include printers that print text and graphics on paper, film, and other media. Printers connect to a computer using a parallel port or USB port, while you can connect multiple printers to the computer at the same time. Network printers are called high-performance printers that can simultaneously serve several computers connected to it in the order of a common queue.

Distinguish petal, thermal, special, dot-matrix, inkjet and laser printers.

Petal and thermal printers are rarely used at present, special printers are used for printing on the surfaces of parts, fabrics, glass, etc. The most frequently used are dot-matrix, inkjet and laser printers.

Dot matrix printers consist of a printhead moving along the paper; in the head are thin rods that move with an electromagnet. The “ejection” of a certain combination of needles hits the ink ribbon, printing an image of a certain set of points on paper. With a consistent set of printed points is obtained the outline of a symbol. Matrix printers are distinguished according to the width of the carriage: “wide” printers are used when printing on A3 paper, and “narrow” - on A4 paper.

Dot-matrix printers are printed in the following modes:

• draft - low-quality printing;

• NLQ - high quality printing;

• graphic.

Most often, matrix printers have the following set of font sizes:

• pica - 10 characters / inch;

• elite - 12 characters / inch;

• proportional spacing - proportional, when the width of different letters is not the same, as a result there may be a different number on one inch.

In addition to black and white color matrix printers are also used.

In inkjet printers, in contrast to dot-matrix, the principle of printing needles is not used. Instead, microscopic ink drops are ejected through the nozzles of the printer head. This significantly improves the speed and quality of printing in graphics modes.

Of the color printers, the most common are three- and four-color printers, and the cheapest are printers with one cartridge used at the same time.

Laser printers differ from the others in that the image in them is formed by a laser beam on a photosensitive drum inside the printer. In a place where the beam illuminates the surface of the drum, an electric discharge is formed, attracting the dust particles of dry paint. After the drum touches the paper, the toner melts and leaves a dot print on the paper, forming an image.

Laser printers have high print quality and high speed, but they are more expensive than other printers.

Plotters, or plotters, are devices that are used to draw complex graphic images. Plotters can be of two types: tablet and roll. The sheet in the tablet plotter is fixed as on the drawing board, and the drawing pen moves in two coordinates along the entire sheet. In a roll-to - roll type, the drawing pen moves only along the sheet, and the paper is pulled back and forth by a transport roller, therefore roll-type plotters are much more compact.