Dot Matrix - Usage in Printers

Usage in Printers

In the context of printers, the term mainly refers to low-resolution impact printers, with a column of 8, 9 or 24 "pins" hitting an ink-impregnated fabric ribbon, like a typewriter ribbon, onto the paper. It was originally contrasted with both daisy wheel printers and line printers that used fixed-shape embossed metal or plastic stamps to mark paper.

However, almost all modern computer printers also create their output as matrices of dots, but use a different technology like laser printing or inkjet printing, and are not called Dot Matrix printers. Impact printers survive where multi-part forms are needed, as the pins can impress dots through multiple layers of paper to make a carbonless copy, for security purposes.

All types of electronic printers typically generate image data as a two-step process. First the information to be printed is converted into a dot matrix using a raster image processor, and the output is a dot matrix referred to as a raster image, which is a complete full-page rendering of the information to be printed. Raster image processing may occur in either the printer itself using a page description language such as Adobe Postscript, or may be performed by printer driver software installed on the user's computer.

Early 1980s impact printers used a simple form of internal raster image processing, using low-resolution built-in bitmap fonts to render raw character data sent from the computer, and only capable of storing enough dot matrix data for one printed line at a time. External raster image processing was possible such as to print a graphical image, but was commonly extremely slow and data was sent one line at a time to the impact printer.

Depending on the printer technology the dot size or grid shape may not be uniform. Some printers are capable of producing smaller dots and will intermesh the small dots within the corners larger ones for antialiasing. Some printers have a fixed resolution across the printhead but with much smaller micro-stepping for the mechanical paper feed, resulting in non-uniform dot-overlapping printing resolutions like 600x1200 dpi.

A dot matrix is useful for marking materials other than paper. In manufacturing industry, many product marking applications use dot matrix inkjet or impact methods. This can also be used to print 2D matrix codes, e.g. Datamatrix.