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Printer and Its Types


Printer is the most popular output device that produces output in a permanent readable form, known as hard copy. Computer printers are commonly divided into two general classes according to the way they produce images on paper. They are : impact printer and non-impact printer.

Impact Printer
Impact printer is a printer that uses a mechanical hammering device to produce each character. Each hammer is embossed with the shape of an alphanumeric character and is transferred through the inked ribbon onto the paper, resulting in a printed character. They are relatively slow, noisy and inexpensive. They can withstand dusty environment, vibrations and extreme temperature. The most popular kinds of impact printer are drum printer and dot-matrix printer. 

Drum Printer
Drum printer is an impact printer that consists of a cylindrical drum on which characters are embossed and it rotates at a uniform speed. There is a magnetically driver hammer in each character position of a line. A character is printed by striking a hammer against the embossed character on the surface. The hammer hits the ribbon and paper against the desired character on the drum when it comes in the printing position. It is capable of printing at a very high speed ranging from 125 to 3000 lines per minute and is very expensive.

Dot Matrix Printer
Dot matrix printer is an impact printer that uses a movable print head consisting of pins. These pins, when pressed against a ribbon and paper; cause small dots to be printed. The more pins that a print head contains, the higher the printer's resolution. The lowest resolution dot matrix printers have only nine pins; the highest resolution printers have twenty-four pins. The speed of dot matrix printer is measured in character per second (cps). Dot matrix printers are inexpensive and relatively fast, but they do not produce high-quality output.

Non-impact printer
Non-impact printers are those in which the printing is done with thermal, chemical, electrostatic, laser beam or inkjet technology for printing. The quality of printing is very high. They are less noisy, faster and produce high-quality graphics. The most popular kinds of impact printers are ink jet printer and laser printer.

Laser Printer
Laser printer is a popular type of personal computer printer that uses a non-impact, photocopier technology. When a document is sent to the printer, a laser beam "draws" the document on a selenium-coated drum using electrical charges. After the drum is charged, it is rolled in a toner, a dry powder type of ink. The toner adheres to the charged image on the drum. The toner is transferred onto a piece of paper and fused to the paper with heat and pressure. After the document is printed, the electrical charge is removed from the drum and the excess toner is collected. Laser printers are very expensive but they produce high-quality output.

Ink-jet printer
Ink-jet printer is a high quality non-impact printer that forms characters by spraying small drops of ink onto the paper. A special ink with high iron content is used. The droplets of ink are charged electrically after being lead onto a nozzle. The droplets are then guided to thin proper positions on paper by electrically charged deflection plates. Inkjets are usually inexpensive, quiet in operation and produce high-quality output.

Plotter is a specialized output device that produces high-quality drawings, maps, charts, and other forms of graphics. Unlike a regular printer, the plotter can draw continuous point-to-point lines directly from vector graphics files or commands. There are a number of different types of plotters: a drum plotter draws on paper wrapped around a drum which turns to produce one direction of the plot, while the pens move to provide the other direction; a flatbed plotter draws on paper with positively charged toner. They are most frequently used for CAE (computer-aided engineering) applications such as CAD (computer-aided design) and CAM (computer-aided manufacturing).