Extel Corporation

Donald P Martin

Richard G Ryan

A descender printing system for a dot matrix printer, comprising a detector for detecting code words representative of descender characters (lower case letters, punctuation, fractions, etc.) prior to printing, and shift means for actuating the line feed mechanism of the printer to advance the paper by two or more dot heights and thereby print the descender elements of such characters below the normal base line. The shift means again actuates the line feed mechanism to return the paper to its original position when the next non-descender character is to be printed.

Descender printing system for dot matrix printer

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.

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Chicago, IL, United States of America

Donald P Martin