Within-line color change printing

In a printer of the type in which a carriage carrying a printhead is traversed on stationary guide means along a paper-supporting platen to form characters by driving a printing element against an inked ribbon interposed between the printhead and the paper, a means for shifting the ribbon to bring different colored portions into alignment with the printing head, said shifting means comprising:

• means for effecting a change of color within a single line from at least four colors of a multi-color ribbon during carriage traverse and printing of that line entirely independent of the position of the carriage along the line including;
• a cable extending generally from one end of the platen to the other;
• mounted on said carriage, a pair of pulleys which are fixedly journaled with respect to said carriage and a third pulley which is indirectly mounted so as to be movable with respect to the pair, the cable passing sequentially over one of the pair, the movable pulley and the other of the pair so that the position of the movable pulley is controllable as a function of the free length of the cable, the portions of the cable on opposite sides of the carriage being parallel to each other and to the direction of movement of the carriage;
• an electromagnetically controlled attachment means for one end of said cable having first and second states, a change between said first and second states providing a predetermined change of a first value in the free length of said cable, said attachment means being fixedly mounted with respect to said guide means;
• a second electromagnetically controlled attachment means for the other end of said cable also having first and second states, a change between said first and second states of said second attachment means providing a predetermined change of a second value in the free length of said cable, said second value being essentially twice that of said first value so that four different variations of cable free length can be effected, said second attachment means also being fixedly mounted with respect to said guide means;
• means for variably positioning a multi-color ribbon of at least four colors between said printing element and said platen;
• and
• means coupling said positioning means to said movable pulley whereby the position of the ribbon with respect to the printing element can be varied independently of carriage position by controlling the states of said attachment means.