DONALD MARTIN, D.C.
Chiropractic in Chicago, IL

3990559, Nov 9, 1976

Oct 20, 1975

5/624054

Donald P. Martin - Chicago IL
Richard G. Ryan - Elmhurst IL

Extel Corporation - Northbrook IL

B41J 304

197 1R

A method and apparatus for controlling the print rate of a column-sequential dot matrix printer actuated by an input signal comprising a sequence of code words occurring at a given maximum input rate, a print head and a print head drive operating at a speed determined by the frequency of a print rate timing signal, and a multi-stage FIFO input storage register. A multiplicity of constant-frequency print rate timing signals are generated, ranging in frequency from substantially below to substantially above a normal print rate frequency Fn approximately matched to the input rate, and a variable print rate timing signal progressively increasing in frequency from well below Fn to well above Fn is also generated; these signals are applied to the printer in accordance with a predetermined schedule, determined by the number of code words in storage at the beginning of each spacing character cycle, and in accordance with a program affording relatively smooth acceleration and deceleration of the print head. In continuing operation, the number of code words in storage is accumulated to a given level and maintained approximately at that level until the input is interrupted.