Abstract: A release-type dot print head formed by joining together a magnet unit, and an armature unit formed by brazing torsion bars to armatures and supporting parts formed integrally with a second yoke with the armatures in a state in which the free ends of styluses fixed to the free ends of the armatures project from the outer surface of a stylus guide attached to the second yoke by a predetermined length. Portions of the free ends of the styluses projecting from the outer surface of the stylus guide are cut off by a wire-cut electrical discharge cutting process with the styluses in a free state to adjust the length of projection of the free ends of the stylus to a predetermined length. The second yoke and the stylus guide are formed respectively of materials having substantially the same coefficients of thermal expansion. The armature unit is subjected to heat treatment after assembly.

Abstract: A printing head comprises a plurality of printing wires, a plurality of armatures connected at their tips to the base ends of the printing wires, an armature supporting member for rotatably supporting the plurality of armatures so that the tips of the armatures are movable in the longitudinal direction of the printing wires, a reciprocable drive unit for driving the plurality of armatures to reciprocate the plurality of printing wires between a projected position and a drawn position in the longitudinal direction of the plurality of printing wires, and wear resistant chips mounted on the rotatably supporting portions of the plurality of armatures on the armature supporting member.

Abstract: A dot printer head in which each radially directed armature is urged to pivot about its primary fulcrum in the return direction by a metallic return spring and is urged to pivot in the opposite angular direction by a metallic holding spring. The metallic return springs and metallic holding springs are sized and positioned so that the metallic holding springs exert a torque urging the radially directed armature to pivot in the actuating direction that is lower than the torque urging the armatures to pivot in the return direction.