US 4,376,942 AGranted

Thermal printing system

AssigneeCubic Western Data

InventorsJohn E. Toth, Wayne M. Spani, Chandler R. Deming, Anthony W. Cumo

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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.

Claims7

Dependent claims

A thermal printing system for rapidly printing alphanumeric information in dot matrix format consisting of a plurality of columns of dots on stock coated with material having a predetermined threshold temperature at which it changes color, comprising;

a print head including a plurality of print elements arranged in a row, each print element adapted to be selectively heated in an amount proportional to the amplitude of an electric current made to flow therethrough;
means for supporting and propelling the stock past the print head adjacent to the print elements and in a direction extending generally perpendicular to the row of print elements;
control means for receiving commands representative of the format and the text of the alphanumeric information to be printed and for decoding the commands and storing data representative of the columns of dots to be printed;
and
driver means responsive to the control means for causing each column of dots to be printed by sequentially causing a preheat current, a print current and zero current to flow through a first portion of the print elements and the preheat current to continuously flow through a second remaining portion of the print elements, the amplitudes of the preheat current and the print current being sufficient so that the temperature of the print elements of the first portion rapidly fluctuates above and below the threshold temperature whereby the columns of dots can be printed in rapid succession.

2 more elements

Dependencies are inferred from the claim text.