How Does a Dot-Matrix Printer Work?
In the 1970s and 1980s, dot-matrix printers were extremely popular in both offices and homes. For a while, they were the only printer that could output graphics or do multiple colors, and once laser printers and inkjet printers entered the market, dot-matrix printers enjoyed a significant cost advantage. Today they are relatively rare, having been supplanted by quieter, faster, cheaper and higher resolution laser and inkjet printers. But they still remain useful in applications like multi-part forms that require the printer to actually strike the paper.
Dot-matrix printers use a piezoelectric print head that pushes pins out towards the paper, making patterns as it moves across the page. For example, a nine-pin print head might make a capital L by firing all nine pins once to make the vertical line, then firing the bottom pin eight times, one after another, to make the L's tail. Dot-matrix printers with more pins, like 24-pin models, are capable of higher quality printing since they use smaller dots to produce their output.
The ribbon sits between the print head and the paper. When the pins emerge from the print head, they press the ribbon into the paper. Ribbon cartridges typically have a length of pre-inked fabric ribbon wound inside of them. As the printer prints, it advances the ribbon and gradually uses it up, necessitating its replacement.
While many dot-matrix printers can accept individual sheets like a laser printer or an inkjet, their strength comes in their ability to work with continuous feed paper. Most dot-matrix printers have a sprocket drive that grabs hold of the pre-punched perforated strips on either side of the special paper and feeds the paper through the printer that way. This enables the printer to generate output in continuous sessions with few paper jams.
Dot-matrix printers have two key drawbacks. The first is that they are very noisy due to the printer pins' hammering effect when they strike the paper. While the noise level varies from printer to printer, expect to hear a cacophonous combination of a loud whine and the thudding sound of the paper feed. Their second drawback is that they produce low resolution output with a visible dot structure. The highest quality dot-matrix printers usually print at 240 dots per inch, which is less than the lowest quality laser printers that can print 300 dots per inch.
Dot-matrix printers have two key advantages. The first is that their continuous feed paper-handling systems allow them to work reliably with relatively few paper jams and lets them be loaded with large quantities of paper at once. The second is that they work well with pressure-sensitive business forms that require an impact to generate multiple copies.