Patent GB-1342771-A (GB)
Title: Apparatus and method for printing serially-received data
IPC: G06K15/07
Filed: 1971-01-18
Abstract: 1342771 Printers MOHAWK DATA SCIENCES CORP 18 Jan 1971 [3 April 1970] 2300/71 Heading G4H A drum-type on-the-fly line printer with a row of print actuators, has first storage means adapted to store characters to be printed in a first group of columns at the beginning of the line, and further storage means adapted to store characters to be printed in subsets of the remaining columns, the further storage means being associated with successive ones of the subsets in turn until all the columns have been printed in, the print actuators associated with the first group of columns being disabled during advance of the documents to the next line. A series of 80 six-bit characters (some of which may indicate spaces) to be printed in a line, are supplied in turn serial-by-bit to a register which converts each to parallel-by-bit form and to a bit counter which enables a function decoder after each 6 bits. The register output is supplied to the function decoder and to 8 character registers, each character being loaded into one of these registers under control of a counter arrangement so that the first 8 characters go in the 1st-8th registers respectively, and each succeeding 4 characters go into the 5th-8th registers respectively. A type-drum rotating about an axis parallel to the line of print has a complete font in each circumferential column, the character coming into printing position at each position in the line being indicated by sensing a coded disc rotating with the drum. This character indication is compared with each of the character registers, equality producing a "fire" pulse provided a strobe pulse from the disc and (in the case of the 1st-1th character registers) a "feed complete" signal (see below) are present. The "fire" pulse clears the character register and actuates a respective hammer driver (except that the hammer drivers are all inhibited if the disc indicates "space"), there being one hammer per possible character position in the line. The hammer drivers corresponding to the 1st-4th character registers control respective hammers directly but those corresponding to the other character registers are each connected to the appropriate one of 19 hammers by a hammer select circuit respective to the register. Each such circuit includes a binary counter (advanced after a delay by the "fire" pulse), two separate sets of stages of which are decoded to select row and column respectively of a matrix arrangement to route the hammer driver output to the appropriate hammer. Line (paper) feed is achieved by a pulse from the function decoder which increments a counter, the paper being stepped (to the next line) with production of a pulse to decrement the counter, a zero count stopping the stepping and producing the "feed complete" signal. Characters to be printed continue to be received at the system input during stepping of the paper and during printing. The time for one revolution of the drum is four times the time between arrivals of successive characters at the system input. As a modification, there may be a hammer for each of the first four positions in the line, and a carriage moving along the line and bearing a plurality of hammers shared between the remaining positions.