Abstract: A printing head comprising a plurality of armatures which are arranged radially and which are swingable before and behind, an armature stopper having armature abutting portions of cantilever type provided in projection toward a center in a radial direction at respective locations at the back of the armature for positioning the armatures under a waiting condition, the armature stopper being displaceable by impingement of the armatures, and a gap defined at the back of the armature abutting portions.

Abstract: A printing head includes solenoids arranged in an annular array for driving needles which are arranged in a zigzag array of two vertical columns. Solenoids corresponding to needles forming one of the columns are arranged on a semicircle of the annular array in the same order as that of the needles on the needle column. Two solenoids respectively corresponding to needles disposed at lower ends of the two needle columns are designed to generate magnetic fluxes whose directions are the same. During underline printing where these two solenoids are alternately energized, the magnetic flux generated by one of the solenoids never acts to increase an effective magnetic flux of the other solenoid at an initial stage of the excitation period thereof, so that the needle of the first solenoid reaches its forwardmost position at an appropriate time. The needle is rapidly restored and its tip prevented from being caught by the ink ribbon.

Abstract: A print head for a dot printer having a plurality of needles for printing by projecting the needles selectively from the print head. The print head has a solenoid base having a plurality of solenoids arranged in a circle thereon for driving the needles, a heat conductor having one side fixed in heat conducting relationship to one surface of the solenoid base and having a heat radiating portion extending in one direction from the solenoid base for radiating heat conducted thereto from the solenoid base, and a connecting portion extending in another direction from the solenoid base, a printed circuit board mounted on the side of the heat conductor opposite the one side, and an electrical connector for receiving a cable for supplying signals to a circuit on the printed circuit board and mounted on the connecting portion and electrically connected to the circuit on the printed circuit board.

Abstract: A dot matrix print head has a print wire unit having a plurality of print wires, an armature unit having a plurality of armatures, each corresponding to the print wire, and an electromagnet unit having electromagnets. Each wire comprises a wire body and a head. A return coil spring is provided between the head of the print wire and a guide plate. The return coil spring has a small diameter end portion engaged with the head and a large diameter portion engaged with the guide plate and has a substantially conical peripheral shape. The large diameter portion engages a recess, thereby preventing rotation of the spring.

Abstract: A printing head comprises a plurality of printing wires which are disposed in alignment with each other and for reciprocal motion. Each of the printing wires is formed by a main body member made of powdered high speed steel, and a chip member made of a rhenium base alloy and welded to an outer tip end of the main body member by means of partial welding. Further, a wire guide member made of zirconia is provided to guide the wire for reciprocal motion of the wire.

Abstract: A rotor assembly for a stepping motor, in which a protecting member fixedly is mounted on a rotor shaft and including a hub portion extending coaxially with the rotor shaft, and at least one face portion radially outwardly extending from said hub portion, and a rotor magnet having an inner bore and an outer periphery formed by etching a magnetic body of an intermetallic compound is mounted on the protecting member.