Dot Matrix Printer

Dot Matrix Printer

              Dot matrix printer was by far most popular printer for PC systems. Compared to its predecessors, daisy wheel printers and adapted electric typewriters, it was faster, relatively quieter, included more fonts and print sizes, and offered flexibility for cut-sheet paper or continuous-feed paper and forms. For these same reasons, dot matrix printers are still in use in many offices. Dot matrix printers for PCs have two standard sizes: narrow and wide. A narrow width printer is usually limited to 80 columns and is  typically used only for correspondence or forms. A wider dot matrix printer has a 132-column width and can e used as a general printer.

Dot Matrix Printer

              Compared to inkjet and laser printers, dot matrix printers are slow and noisy. However, in environments where printing on multi-part or continuous-feed preprinted forms is more important than the printer's noise or speed, dot matrix printers continue to thrive. For this reason, you will commonly see dot matrix printers in pharmacies, receiving docks, warehouses, and other administrative offices etc.

             

              sample output from 9-pin dot matrix printer (one character expanded to show detail)

The term dot matrix printer is used for impact printers that use a matrix of small pins to transfer ink to the page. The advantage of dot matrix over other impact printers is that they can produce graphical images in addition to text; however the text is generally of poorer quality than impact printers that use letter-forms (type).

Dot-matrix printers can be broadly divided into two major classes:

• Ballistic wire printers
• Stored energy printers

Dot matrix printers can either be character-based or line-based (that is, a single horizontal series of pixels across the page), referring to the configuration of the print head.

                In the 1970s & 80s, dot matrix printers were one of the more common types of printers used for general use, such as for home and small office use. Such printers normally had either 9 or 24 pins on the print head (early 7 pin printers also existed, which did not print descenders). There was a period during the early home computer era when a range of printers were manufactured under many brands such as the Commodore VIC-1525 using the Seikosha Uni-Hammer system. This used a single solenoid with an oblique striker that would be actuated 7 times for each column of 7 vertical pixels while the head was moving at a constant speed. The angle of the striker would align the dots vertically even though the head had moved one dot spacing in the time. The vertical dot position was controlled by a synchronised longitudinally ribbed platen behind the paper that rotated rapidly with a rib moving vertically seven dot spacings in the time it took to print one pixel column. 24-pin print heads were able to print at a higher quality and started to offer additional type styles and were marketed as Near Letter Quality by some vendors. Once the price of inkjet printers dropped to the point where they were competitive with dot matrix printers, dot matrix printers began to fall out of favour for general use.

              Some dot matrix printers, such as the NEC P6300, can be upgraded to print in colour. This is achieved through the use of a four-colour ribbon mounted on a mechanism (provided in an upgrade kit that replaces the standard black ribbon mechanism after installation) that raises and lowers the ribbons as needed. Colour graphics are generally printed in four passes at standard resolution, thus slowing down printing considerably. As a result, colour graphics can take up to four times longer to print than standard monochrome graphics, or up to 8-16 times as long at high resolution mode.

             Dot matrix printers are still commonly used in low-cost, low-quality applications such as cash registers, or in demanding, very high volume applications like invoice printing. Impact printing, unlike laser printing, allows the pressure of the print head to be applied to a stack of two or more forms to print multi-part documents such as sales invoices and credit card receipts using continuous stationery with carbonless copy paper. Dot-matrix printers were being superseded even as receipt printers after the end of the twentieth century.