GB1372742A - Thermal printing system - Google Patents

Abstract

1372742 Printers AMERICAN MICROSYSTEMS Inc 14 Dec 1971 [1 Dec 1971] 57897/71 Heading G4H [Also in Division B6] A thermal printing system comprises a print head having upper and lower planar ceramic plates separated by a metallized layer and bearing further such layers on their other planar surfaces, one of these forming a series of master characters, the layers being interconnected through the ceramic plates, each master being comprised of a plurality of segments capable of forming a plurality of different human-readable characters when viewed in preselected segment combinations, and combinations of these segments being energized electrically on a sequential time-sharing basis to print the required characters. Each master charcter is in the shape of a roughly rectangular Fig. 8, a combination of the 7 segments (bars) of this being energized. Decimal points are also provided, and an initial minus sign, the printer being used in an electronic calculator or measurement system. A line of 8 characters to be printed is supplied in binary-coded-decimal form, serial by character, parallel by bit, to a decoder which energizes a combination of 7 output lines corresponding to the segments, and an 8th line for the decimal point. The 8 lines feed respective 4-bit shift registers of first and third groups of 4 registers per group, then similar registers of second and fourth groups. The contents of the first group are read out in parallel (16 bits) to 16 triacs to energize selected respective segments of 4 of the character positions, then the second group is similarly read out to the triacs to energize selected corresponding segments of the other 4 character positions, then the third and fourth groups are read out in turn for the other segments and decimal point. The durations of the signals to the triacs are adjustable to allow for different types of paper, or in accordance with print head temperature. In the print head, the middle metal layer forms interconnections to be linked to earth connectors, and the remaining metal layer provides drive and earth connectors. A thick metal support member for the print head aids heat dissipation.