daisywheel printer

daisywheel printer An obsolete type of serial impact printer formerly widely used on word-processor systems for producing letters and documents. The font was formed on the end of spring fingers extending radially from a central hub. The font carrier was rotated by a servosystem until the correct character was opposite the printing position and a single hammer impacted it against the inked ribbon and paper. The carriage with the font and hammer – and usually the ribbon – was then moved to the next printing position in the line. The print head and paper position could generally be incremented bidirectionally by control commands, making possible proportional spacing, justification, subscript and superscript characters, etc.

The daisywheel printer was introduced by Diablo Systems Inc. in 1972 and represented a considerable improvement in speed and reduction in mechanical complexity compared to other typewriters then used as low-speed printers. The speed was initially 30 characters per second with a repertoire of 96 characters. Developments led to speeds of 65 cps for average text and up to 192 characters on the type wheel; by overprinting it was possible to form a further 250 characters. This development partially overcame the disadvantage – relative to matrix printers – of the limited character set. By 1990, however, daisywheel printers had been superseded by faster, more flexible, and quieter dot matrix printers and page printers.