Abstract: An impact line printer comprising a print ribbon wound on a pair of spools for traversal in two directions across a plurality of print hammers having tips for impacting the print ribbon to print on a media. A permanent magnet having two pole pieces having pole piece ends in adjacent relationship to the print hammers retains the print hammers until a coil in associated relationship with each pole piece releases the magnetic retention of the hammers. A magnetically permeable extension is longitudinally adjacent each hammer which acts as a magnetic shunt to permit more rapid printing rates and higher impacts. The extensions conduct and shunt magnetic flux from the hammers through the longitudinally adjacent extensions.

Abstract: An impact printer with a hammerbank having print hammers retained by a permanent magnet for impacting a print ribbon, and a mechanical driver for moving the hammerbank across print media. First and second coils for each hammer are wrapped around first and second pole pieces, one of which is asymmetrical to the other pole piece. One of the pole pieces can have a generally elongated longitudinal form with the coil wound around the longitudinal form and the other can have a generally arcuate form, with the coil wrapped on a portion between the ends thereof. The coil wrapped around the arcuately formed pole piece is thicker than the coil wrapped around the longitudinal pole piece. The result is to provide pole pieces and coils for an impact printer having differing spatial relationships that can be staggered, or formed asymmetrically for more compact coil and pole piece placement to improve printer efficiency.

Abstract: An impact printer having one or multiple lines of hammers on a hammerbank for impacting a print ribbon against a print media after release by one or more electrically energized coils in a magnetic circuit with one or more pole pieces retaining the hammers prior to impact. One or more of the coils has a spaced winding thereby allowing filling of the spaced winding during return winding. Another embodiment utilizes a longitudinal return from an initial winding which can be formed with multiple layers or multiple overlappings of the longitudinal return. The foregoing minimizes a first dimension while having controlled wire crossing resulting in expansion in a second dimension, thereby allowing compaction of magnetic circuits in the first dimension.