Electronic control circuit for a high speed bidirectional printer

Abstract

An electronic control circuit is designed for use with a high speed printer having a character generator which is coupled to a print head. The print head is laterally displaced along a print line by a stepper motor and forms characters from a plurality of columns of dots as the print head moves. The electronic control circuit includes an encoder which is coupled to the shaft of the stepper motor to generate count up pulses when the stepper motor displaces the print head in a first direction and count down pulses when the stepper motor displaces the print head in a second direction. The count up and count down pulses permit the control circuit to continuously define the present print head position. A random access memory receives printable characters during a load cycle and reads out printable characters to the character generator during a print cycle. A data formatting control is provided to format input data, to load the memory with the formatted data, to compute a desired print head position during each load cycle and to initiate the print mode at the end of each load mode. An up/down counter receives the count up and count down pulses and converts them into digital address signals for the memory and for the character generator to cause the print head to print selected characters at selected positions along the print line in response to displacements of the stepper motor. A motor control is provided to controllably accelerate and decelerate the print head during each print cycle.