Abstract: A twin counterweight, shuttle drive (11) for a reciprocably mounted dot matrix line printer carriage (13) that is shock stabilized to: (a) eliminate instability when the printer is bumped; and, (b) maintain the center point of the carriage peak-to-peak travel in the same position even when the printer is inclined, is disclosed. The shuttle drive (11) comprises a pair of equally sized and configured weight unbalanced gears (43) rotatably coupled together and secured to the mounted dot matrix line printer carriage (13). Rotation of the weight unbalanced gears (43) creates a drive force that shuttles the carriage (13). The gears (43) are positioned such that the drive force is aligned with the center of gravity of the carriage (13) and such that the centers of rotation of the gears (43) lie on a line that is perpendicular to the line of shuttle motion.

Abstract: A hammer module (11) for a dot matrix line printer including a cantilever mounted multi-arm hammer (23) formed from a single piece of resilient ferromagnetic material is disclosed. The multi-arm hammer (23) comprises a plurality of hammer arms (25) each including a thin spring region (51) and a thick head region (53) that lie in a plane that forms a slight angle with the plane of the base (27) of the multi-arm hammer (23). Each module also includes magnetic circuits for each hammer arm (25) formed by a common permanent magnet (13), a post (19), an arm (29) of a flux plate (15) and an arm (33) of a return plate (17). The post (19) is mounted on the tip of the flux plate arm (29). The flux plate and return plate arms (29 and 33) lie in parallel planes located on opposite sides (poles) of the permanent magnet (13).

Abstract: A linear motor shuttling system for shuttling the print head (11) of a dot matrix line printer is disclosed. The print head (11) is supported by a pair of flexures (13, 15) such that the head is free to move back and forth along a print line. One end of the flexure supported print head is attached to the coil (31) of a voice coil linear motor (23). The linear motor (23) is also flexure (27, 29) supported. The linear motor (23) is positioned such that the axis of coil movement is co-axial with the axis of movement of the print head (11). Further, the resonant vibration frequency of the combination of the linear motor and the linear motor flexure support is tuned to the resonant vibration frequency of the combination of the print head and the print head flexure support.

Abstract: A print hammer actuator system for a dot matrix line printer comprising a plurality of coils greater than the number of dot imprinting hammers to be actuated by the coils is disclosed. The coils (C1, C2 . . . C80 or 61, 62, 63 . . . 69) are mounted side-by-side in a fixed position; and, the hammers (H1, H2 . . . H40 or 51, 53, 55, 57) are oscillated back and forth in the regions where magnetic fields are produced by energized coils. As the hammers are oscillated, the coils are selectively energized and de-energized to actuate the hammers. Energizing the coils attracts the hammers toward the coils, against the spring force of the hammers. De-energizing the coils releases the hammers, whereby the stored spring energy creates a dot. Depending upon the position of the hammers, either one or two coils are energized and de-energized to actuate a single hammer.