GB825782A - Electronic apparatus for high-speed printers - Google Patents

Abstract

825,782. Selective printing. GENERAL, ELECTRIC CO. March 22, 1957 [Aug. 27, 1956], No. 9428/57. Class 100(4) A high-speed printing machine comprises a line length of columns of characters, each column of which is successively moved through a printing position and as each character reaches printing position, equivalent first signals are sensed on a code wheel 14 by a sensing head 18 and are compared with second or input signals 22 in a coincidence device 40 whereupon identity of signals actuates a hammer-control apparatus to print on a paper web 26a through ink-ribbon 26. For each line of characters there are a plurality of coincidence devices 40, fed by two-part registers 30A, 30B into which the printer input signals are successively entered and circulated. In the embodiment described the characters are on a drum 10, required to make one complete revolution per line, and the paper advances one line after each revolution of the drum. A seven bit binary code is used and each register can hold 84 bits (twelve characters) 42 bits in each part which are circulated simultaneously so that the contents of the registers for a line of type is scanned in much less time. Circulation is enabled by a shift pulse generator 39 and occurs from the centre of the register to the front end and from the back end of the register to the centre. The shift pulse generator 39 is connected to the seven outputs of a bitphase ring counter 37. After the output of the counter is filled, it is applied via an AND gate 34, to a column-phase ring counter 38 which can count a total of six counts before it returns to its initial position to deal with the seventh character of the line. The outputs of counter 37 are applied to other AND gates 50A- 50F. The first signals, for comparison purposes, are applied from the code wheel 14 to all the coincidence devices 40A, B simultaneously and outputs from the coincidence devices 40A, B are also applied to the AND gate 50A-50F. Flip-flops 52A-52F are connected to each AND gate 50A-50F, and to the outputs from the column-phase ring counter 38. The coincidence device 40A, if it finds that the contents of register A and the code-wheel indications are identical, applies its output to all AND gates 50A-50F simultaneously. However, since only AND gate 50A has the required enablng input from the column-phase ring counter, only it will be enabled to provide an output which drives the associated flip-flop 52A. If the flip-flop 52A has been driven to its set condition, it is enabled to prime for firing an associated thyratron valve 56A, which, when subsequently fired by a pulse from the source 62, can energize a hammer which prints a character at the column position for that hammer. Another required input to AND gate 50A before it can drive the flip-flop 52A, is an output from a non-zero on the code wheel 14. This controls circuitry so that zeros which have no significance are not printed.