Printers

Printers are devices for outputting data from a computer, forming a point-by-point copy of documents on paper or other similar material, for example, a transparent film. Printers are very diverse in terms of the operation and quality of the image reproduction, the size of the paper on which they can reproduce it, as well as the ability to print color or only black and white images and print speeds. The main characteristic of the printer, determining the quality of the paper document received, is the resolution, measured by the number of dots, which are placed on one inch - dots per inch (dpi). The higher the resolution, the more accurately the image details are reproduced. Modern printers provide a resolution of 200 to 2880 dpi. Another important characteristic is the printer's performance, which is measured by the number of pages produced by the printer per minute - page per minute (ppm). Usually, performance is specified for the A4 format pages.

Printers are devices for outputting data from a computer, forming a point-by-point copy of documents on paper or other similar material, for example, a transparent film

Matrix printers form an image of points that are obtained by hitting a thin needle on the ink ribbon, pressed at the time of impact to the paper. The needles, numbering from 9 to 24, are united in the head and placed vertically in one row in it. For one pass of the head, a strip is obtained, whose height at points is equal to the number of needles in the head. Matrix printers have a low speed, which is about 2 ppm. The resolution is 200-360 dpi. Matrix printers have a low cost of consumables (ink ribbon) and the ability to print multiple copies of a document at the same time.

Inkjet printers in our country are currently the most common printers. The print head of the inkjet printer, instead of needles, contains thin tubes-nozzles, through which the minute dosed drops of dye are thrown onto the paper. The number of nozzles in the head is from 12 to 64. Inkjet printers also perform color printing. With color printing, the color point is obtained by mixing in the specified proportions the dyes of the three primary colors: cyan, magenta and yellow, fired from three nozzles. Inkjet printers have a high resolution, which depends on the number of nozzles in the head and is from 300 to 1200 dpi; high printing speed (up to 10 ppm); noiseless operation.

Laser printers provide the best quality print with the highest resolution and speed. The image in them is formed in several stages. At the first stage, a narrow intermittent light beam is illuminated from the laser diode of the drum, on which a thin layer of material is electrolyzed under the action of light. At the second stage, the drum is sprinkled with a fine-dispersed coloring powder, which adheres to the drum at the points of exposure, and the excess powder is removed. The third stage consists in rolling the drum with the powder adhering to it on paper, as a result of which the dye passes to the paper. At the last stage, the paper is thermally treated. It is heated to 2000 C, as a result, the powder melts and, penetrating into the paper structure, is fixed on it. Laser printers can print a color image. Laser printers have high print quality, high printing speed (up to 40 ppm), as well as low cost of copy and noiseless operation.

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