page_title: Dot matrix printing
section_title: Variations
hierarchical_section_title: Dot matrix printing / Variations
caption_attribution_description: English: Epson Wide Carriage 9-pin printer - with legal paper 8.5x14, friction feed only
context_page_description: Dot matrix printing, sometimes called impact matrix printing, is a computer printing process in which ink is applied to a surface using a relatively low-resolution dot matrix for layout. Dot matrix printers typically use a print head that moves back and forth or in an up-and-down motion on the page and prints by impact, striking an ink-soaked cloth ribbon against the paper, much like the print mechanism on a typewriter or line printer. However, a dot matrix printer is able to print arbitrary patterns and not just specific characters.
  The perceived quality of dot matrix printers depends on the vertical and horizontal resolution and the ability of the printer to overlap adjacent dots. 9-pin and 24-pin are common; this specifies the number of pins in a specific vertically aligned space. With 24-pin printers, the horizontal movement can slightly overlap dots, producing visually superior output, usually at the cost of speed.
  Dot matrix printing is typically distinguished from non-impact methods, such as inkjet, thermal, or laser printing, though they too may use a bitmap to represent the printed work.
context_section_description: The common serial dot matrix printers use a horizontally moving print head. The print head can be thought of featuring a single vertical column of seven or more pins approximately the height of a character box. In reality, the pins are arranged in up to four vertically or/and horizontally slightly displaced columns in order to increase the dot density and print speed through interleaving without causing the pins to jam. Thereby, up to 48 pins can be used to form the characters of a line while the print head moves horizontally. The printing speed of serial dot matrix printers with moving heads varies from 30 to 1550 cps. 
  In a considerably different configuration, so called line dot matrix printers use a fixed print head almost as wide as the paper path utilizing a horizontal line of thousands of pins for printing. Sometimes two horizontally slightly displaced rows are used to improve the effective dot density through interleaving. While still line-oriented, these printers for the professional heavy-duty market effectively print a whole line at once while the paper moves forward below the print head. Line matrix printers are capable of printing much more than 1000 cps, resulting in a throughput of up to 800 pages/hour.
  A variation on the dot matrix printer was the cross hammer dot printer, patented by Seikosha in 1982. The smooth cylindrical roller of a conventional printer was replaced by a spinning, fluted cylinder. The print head was a simple hammer, with a vertical projecting edge, operated by an electromagnet. Where the vertical edge of the hammer intersected the horizontal flute of the cylinder, compressing the paper and ribbon between them, a single dot was marked on the paper. Characters were built up of multiple dots.
caption: An example of a wide-carriage printer, designed for paper 14 inches wide, shown with legal paper loaded (8.5"×14")
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