Impact Printers
As the term implies, these printers have metal hammers, which strike a print ribbon as in the case of a typewriter. They are used generally when a carbon copy forms part of the print requirements, eg., receipts
Impact printers are also called Dot Matrix printers as they form characters by printing dots onto paper. Software installed on the host computer send coded electronic signals to the printer to control where the dots are printed. As the print head moves across the paper, the pins on it receive impulses from the computer, which direct where the dots are to be printed. A ribbon impregnated with ink lies between the print head and the paper. As the pins strike out from the print head in response from the computers signals. They force the ribbon against the paper. At these points the dots are printed.
Non-Impact Printers
Non-impact printers use an ink jet spray and no impact is made on the paper. Characters are formed on the paper by a spray of vaporised ink from tiny nozzles, forming a dot print effect. As the ink passes through an electric field it becomes charged and sticks to the paper in the shape of the character to form printed characters on the paper.
Non impact printers give a much better quality of print for text and graphics than an impact printer.
Non-Impact printers include Bubble Jets and Ink Jet printers. Laser Printers are also non-impact printers, however, they operate similar to a photocopier machine