Automatic print wheel element changing mechanism for a serial printer

A rotary type print element interchange mechanism for use on a high speed serial printer, said printer including a frame, a platen over which a printing medium is indexed, a carriage assembly carrying a rotary print element and means for activating selected individual print slugs of said print element, said carriage assembly mounted along a track for movement parallel to said platen, the interchange mechanism comprising:

• said printer having a print section and a change section;
• said track extending into said change section and having an exchange position for said carriage assembly;
• a selectively movable changer mechanism mounted within said changer section and having a rotatable carousel mounted thereon, said changer mechanism having means for moving said changer mechanism and carousel therewith along a path between a load position and a retracted position;
• said path being normal to said track;
• said carousel having a plurality of arms, each of said arms having means for releasably securing a print element thereto;
• said carriage assembly having means for securing a print element thereto;
• said carousel arms and carriage assembly securing means and said print element configured to allow both said carousel arm securing means and said carriage assembly securing means to simultaneously engage said print element when said changer mechanism is in said load position and said carriage assembly is in said exchange position;
• said carousel arm securing means having means for removing said simultaneously engaged print element from said carriage assembly print element securing means when said changer mechanism is moved along said path from said load position towards said retracted position;
• and
• said carriage assembly securing means having means for removing said simultaneously engaged print element from said carousel arm print element securing means when said carriage assembly is moved along said track away from said exchange position.

A method for automatically exchanging rotary print elements on a serial printer, said serial printer having a first print element mounted on a carriage assembly for movement between a printing area and at least one exchange position, said carriage assembly having print element securing means, said serial printer also having a carousel rotatably mounted on a changer mechanism and having a plurality of arms for holding print elements, said changer mechanism mounted for movement toward and away from said exchange position, each of said arms having print element securing means, comprising the steps of:

• requesting a second print element;
• searching a memory to determine which of said carousel arms has said second print element mounted thereon;
• rotating said first print element for alignment with the print element securing means of the carousel arm facing said exchange position;
• moving said carriage assembly to said exchange position whereat said carousel arm print element securing means engages said first print element;
• moving said changer mechanism, said carousel and said first print element away from said carriage assembly to a retracted position;
• indexing said carousel until the carousel arm having said second print element mounted thereon faces said exchange position;
• moving said changer mechanism, said carousel, and said second print element toward said exchange position so that said second print element is engaged by said carriage assembly print element securing means;
• and
• moving said carriage assembly and second print element away from said exchange position toward said printing area whereupon said printer is ready to print.