Typewriting machines – Typing by other than type-face or type-die – Character formation by impact
Patent
1979-10-23
1982-04-27
Sewell, Paul T.
Typewriting machines
Typing by other than type-face or type-die
Character formation by impact
400306, 400322, 400323, B41J 312
Patent
active
043268137
ABSTRACT:
A dot matrix character printer having the capability of printing characters at variable speeds and with variable pitches. Variable pitch is provided through the use of programmable radix counters which control actuation of the printing solenoids. Solenoid actuation is based on print head position, with the actuation position being varied with print head velocity, to compensate for the distance travelled by the print head during the time between solenoid actuation and print wire impact; this permits operation at variable printing rates. Printing rate is limited by the cyclic rate of the print head, with an additional limitation based on dot printing density which prevents excessive heating of the printing solenoids. Control functions are provided by a firmware-controlled microprocessor and a special purpose integrated circuit (PCC). The operation of the microprocessor and PCC are time-independent of each other. For initiating printing, the microprocessor provides a coarse time window and the PCC controls operations within that window.
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Heller Peter N.
Lomicka, Jr. Roy F.
Digital Equipment Corporation
Sewell Paul T.
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