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Dual Column Matrix Print Head Wire Selection Scheme

IP.com Disclosure Number: IPCOM000050165D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 4 page(s) / 63K

Publishing Venue

IBM

Related People

Cockrell, HH: AUTHOR [+2]

Abstract

A wire fire selection technique for dual column wire matrix print heads is described. A particular dual column wire matrix print head has two adjacent columns of eight wires each in the vertical direction with the banks of wires being separated by 30/1000 of an inch. A schematic of this is shown in Fig. 1 showing the relative positions of the wires as asterisks and numbering them 1L through 8L, 1R through 8R for left and right banks, respectively.

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Dual Column Matrix Print Head Wire Selection Scheme

A wire fire selection technique for dual column wire matrix print heads is described. A particular dual column wire matrix print head has two adjacent columns of eight wires each in the vertical direction with the banks of wires being separated by 30/1000 of an inch. A schematic of this is shown in Fig. 1 showing the relative positions of the wires as asterisks and numbering them 1L through 8L, 1R through 8R for left and right banks, respectively.

Wire matrix printers of this type can position character dots anywhere in a desired matrix and at any desired pitch depending upon the speed of the wire matrix print head as it traverses a sheet of paper. For a given repetition rate for a wire firing of 1.176 milliseconds, the print head speed is either 34" per second for 10 pitch characters or 20.4" per second for 16.7 pitch characters. Two rules for constructing characters within an 8 x 10 dot matrix for character fonts are as follows: No horizontally adjacent dots are to be fired within a matrix, and columns 8, 9 and 10 in the 10 x 8 matrix are to be left blank for intercharacter spacing.

Fig. 2 shows the basic constraints just described, and illustrates also the normal wire fire selection process by banks. Across the top of Fig. 2 are the column numbers 1-10 repeated for each of the two adjacent print columns, column X and column X+1, reading from left to right. Below the print column identifiers are Rs and Ls, indicating that either the right or the left bank of wires in the print head are to be fired to print those slices within the print matrix.

It will be noted with the examples shown that at 10 characters to the inch or 10 pitch printing, the wire banks will be three slices apart and at 16.7 character pitch, they will be five slices apart. The wire firing repetition rate is such that any of the 16 wires in the print head may be fired once every 1.176 milliseconds. Running faster exceeds the design point of the print head and may cause overheating.

The alphanumeric printing speed is 340 characters per second for either pitch, and since there are 10 slices per character at each pitch, the time between character slices, as the print head traverses the paper, is 294 microseconds. Therefore, once a wire has been fired, it may not again be fired until four slices later since 4 x 294 microseconds equals 1.176 milliseconds.

The normal approach for printing is to define a specific wire for striking a specific dot within each character in a given font. These instructions are normally coded into ROS (read-only storage) memory. This has major disadvantages, since no customer programmable font would be possible without an expensive ROS change. Also, different dots in a single slice will be fired by different wire banks instead of just one, which causes a deterioration in appearance due to small misalignments.

The present invention uses a technique employing a basic sequence of right, right,...