Thermal printing system

Abstract

A thermal printing system in which printing speed is maximized by electronically controlling the temperature of the print elements in accordance with the varying dot pattern being printed. The system includes a thermal printer module and a printer circuit which are specially adapted to be utilized in a modularized device such as a ticket vending machine. The printer circuit includes a microprocessor which demodulates serial data commands and stores the demodulated data in an input buffer. The microprocessor decodes the information in the input buffer and sets up an output buffer containing character data to be printed on the ticket. The microprocessor causes the character data stored in the output buffer to be printed on the ticket using software timing loops to selectively control the temperature of the individual print elements. The alphanumeric information is printed in dot matrix form on the ticket, in column by column fashion, each column consisting of a plurality of dots representative of portions of characters in separate lines. Each print element has associated therewith solid state preheat and print drivers which sequentially cause a preheat current, a print current and then zero current to flow through the print element when it prints a dot to maximize the speed at which the print element temperature passes the thermal coating threshold temperature.