Impact Printers

Impact printers create an image by using some mechanism to physically press an inked ribbon against the page, causing the ink to be deposited on the page in the shape desired. These printers are typically loud, but remain in use today because of their unique ability to function with multi part forms. So it is called impact printers.

Major Types of Impact printer:

1. Dot-Matrix Printer:
                                   Dot matrix printing or impact matrix printing is a type of computer printing which uses 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. However, unlike a typewriter or daisy wheel printer, letters are drawn out of a dot matrix, and thus, varied fonts and arbitrary graphics can be produced.
2. Daisy-Wheel: Daisy wheel printing is an impact printing technology invented in 1969 by David S. Lee at Diablo Data Systems. It uses interchangeable pre-formed type elements, each with typically 96 glyphs, to generate high-quality output comparable to premium typewriters such as theIBM Selectric, but two to three times faster.
   
                                             Daisy wheel printing was used in electronic typewriters, word processors and computers from 1972. The daisy wheel is considered to be so named because of its resemblance to the daisy flower. By 1980 daisy wheel printers had become the dominant technology for high-quality print. Dot-matrix impact, thermal, or line printers were used where higher speed was required and poor print quality was acceptable. Both technologies were rapidly superseded for most purposes when dot-based printers—in particular laser printers—that could print any characters or graphics rather than being restricted to a limited character set became able to produce output of comparable quality. Daisy wheel technology is now found only in some electronic typewriters.
3. Line Printer: The line printer is an impact printer in which one line of text is printed at a time. They are mostly associated with unit record equipment and the early days of digital computing, but the technology is still in use. Print speeds of 600 lines-per-minute (approximately 10 pages per minute) were achieved in the 1950s, later increasing to as much as 1200 lpm. Line printers print a complete line at a time and have speeds in the range of 150 to 2500 lines per minute. The different types of line printers are drum printers and chain printers.