Dot matrix printing system

Abstract

In the dot matrix printer disclosed herein, a multicolor ribbon is shifted to bring different colored stripes in alignment with the nosepiece of a dot matrix printhead by means of cup-like ribbon guide members journaled on either side of the nosepiece. Each guide member provides, in its periphery, an arcuate slot through which the ribbon can freely slide as the printhead traverses. A stepping motor is coupled to the guide members for rotating them so as to selectively bring a stripe of desired color into operative position.

What is claimed is: 
     
       1. In a dot matrix printer of the type having an elongate platen, a printhead having a projecting nosepiece through which a plurality of print pins are journaled, and means for travesing said printhead along said platen and selectively actuating said pins to effect printing on a web overlying said platen; a .[.multicolor.]. ribbon system comprising: a .[.multicolor.]. ribbon having .[.parallel strips of different colors.]. .Iadd.a plurality of portions.Iaddend.;   stationary ribbon holder means for holding a substantial quantity of said ribbon and for positioning a length of said ribbon generally parallel to said platen;   pivot pin means on each side of said nosepiece .Iadd.for serving as a pivotable mount.Iaddend.;   shiftable ribbon guide .Iadd.member .Iaddend.means including, on each side of said nosepiece, a disk-like base portion and a cylindrical wall means .Iadd.for guiding said ribbon.Iaddend., each wall means being attached to said base portion at spaced locations thereby to form an arcuate slot therebetween, the length of each slot being substantially equal to the width of the ribbon, the base portions being centrally apertured to receive said .Iadd.pivot .Iaddend.pin .[.portions.]. .Iadd.means.Iaddend.;   gear tooth means on .[.the periphery of at least one of said base portions;.]. .Iadd.said shiftable ribbon guide member .Iaddend.means .Iadd.for enabling the guide member means to be rotated.Iaddend.; and   selectively energizable stepper motor means .Iadd.for driving said gear tooth means .Iaddend.including gear means engagable with said gear tooth means for rotating said guide .[.members.]. .Iadd.member means .Iaddend.thereby to roll different .[.stripes.]. .Iadd.portions .Iaddend.of said ribbon into alignment with said print pins.   
     
     
       2. A ribbon system as set forth in claim 1 wherein said guide .[.members.]. .Iadd.member means on each side of said nosepiece .Iaddend.are linked by a .Iadd.connecting .Iaddend.web for movement together. 
     
     
       3. A ribbon system as set forth in claim 2 wherein said .[.members.]. .Iadd.member means .Iaddend.and said .Iadd.connecting .Iaddend.web are integral. 
     
     
       4. In a dot matrix printer of the type having an elongate platen, a printhead having a projecting nosepiece through which a plurality of print pins are journaled, and means for traversing said printhead along said platen and selectively actuating said pins to effect printing on a web overlying said platen; a .[.multicolor.]. ribbon system comprising: a .[.multicolor.]. ribbon having .[.parallel strips of different colors.]. .Iadd.a plurality of parallel portions.Iaddend.;   stationary ribbon holder means for holding a substantial quantity of said ribbon and for positioning a length of said ribbon generally parallel to said platen;   pivot pin means on each side of said nosepiece .Iadd.for serving as a pivotable mount.Iaddend.;   shiftable ribbon guide means including, on each side of said nosepiece, a disk-like base portion and a tapered cylindrical wall portion, each wall portion being attached to the respective base portion at spaced locations thereby to form an arcuate slot, the length of each slot being substantially equal to the width of the ribbon with the ribbon passing through said slots, the base portions being centrally apertured to receive said pin portions, said guide means including an integral .Iadd.connecting .Iaddend.web linking the portions on each side of said nosepiece;   gear tooth means on .[.the periphery of one of said base portions.]. .Iadd.said shiftable ribbon guide means for enabling the ribbon guide means to be rotated.Iaddend.; and   selectively energizable stepper motor means .Iadd.for driving said gear tooth means .Iaddend.including gear means engagable with said gear tooth means for rotating said guide .[.members.]. .Iadd.means .Iaddend.thereby to roll different .[.stripes.]. .Iadd.portions .Iaddend.of said ribbon into alignment with said print pins.   
     
     
       5. A replaceable ribbon assembly for use in a dot matrix printer of the type in which a printhead is traversed along a platen to produce a line of print, the printhead carrying a projecting nosepiece through which a plurality of print pins are journaled, said ribbon assembly comprising: an endless ribbon having .[.parallel stripes of different colors.]. .Iadd.a plurality of portions, each of which is alignable with said print pins.Iaddend.;   a cartridge holding a substantial quantity of said ribbon with a loop extending outside of said cartridge;   a ribbon guide comprising a pair of cup-like sections, each of which includes a cylindrical wall portion and a disk-like base portion, the base portion being spaced apart to receive the printhead nosepiece therebetween with the respective cylindrical wall portions extending in opposite directions, each wall portion being attached to the respective base portion at spaced locations thereby to form an arcuate slot, the ribbon loop passing through said slots, the base portions being centrally apertured to receive pivot pins carried by the printhead nosepiece, at least one of said disk-like base portions being provided with gear tooth means .[.around a portion of its periphery.]. .Iadd.on said ribbon guide for enabling said ribbon guide to be rotated.Iaddend., whereby motor driven gear means .Iadd.for engaging said gear tooth means, and .Iaddend.carried by a printhead can roll said ribbon around the printhead nosepiece thereby to bring different .[.stripes.]. .Iadd.portions of said ribbon .Iaddend.into alignment with the print pins.