A print head includes a coil carrier having upwardly bent legs serving as yokes and being arranged around or upon a permanent magnet whose outer face is coplanar with the end faces of the yokes; a cover plate is mounted on and in that plane having apertures adjacent the space between the permanent magnet and the closest yoke. A set of armature plates is resiliently mounted on the other side of the cover plate respectively adjacent the apertures which are filled with nonmagnetizable material, and the magnet plate of each armature has affixed to it thin, side-wall type members converging towards a main apex-point to which the stylus is mounted.

The invention is a magnetically actuated clapper-style armature wire matrix print head. A light weight highly reliable and low cost design is achieved by utilizing single molded parts wherever possible. A unitary molded straight line channel wire matrix wire guide is molded as a single part. The flux return member is a single formed part with attached magnetic cores. The magnetic cores have thermal contact with an attached or integral heat sink that extend from the flux return member in the axial direction with the cores and which may be integrated with the support frame for the print head structure. A rebound absorbing backstop member receives the armatures on the rebound but also serves as a means of maintaining pivotal contact between the end of the armatures and the top edge of the flux return member so that a continuous flux path from the flux return member, through the armature and down through the cores of the electromagnets can be attained.

The multi-wire dot print head is provided with a plurality of print wires with a wire driving armature associated with each of the print wires and being operable to move the print wire toward a print position. The wire driving armatures each include an actuator lever and a cylindrical movable core mounted intermediate opposite ends of the actuator lever with an electromagnetic actuator associated with each of the armatures for imparting movement thereto. The outer end of the actuator lever is provided with a downwardly depending pivot leg and pivot or fulcrum support means for the actuator lever is positioned in a plane below the level of the open end of a cylindrical bore in the electromagnetic actuator so that a minimum amount of clearance may be provided between the cylindrical core and the cylindrical bore.

A carrier frame is provided for oscillation along a printing platen of the printer and is comprised of two integral, U-shaped sections facing each other at right angles. A plurality of electromagnetic actuators are arranged in one section and include a yoke, a coil, and a pivot armature in each instance. A free end of the pivot armature projects into the other small section. A relatively short print needle is guided in one wall portion of the second section and has its rear end abutment with the projecting end of the armature; an adjusting screw adjusts the relative disposition of the pin-like needle and the armature; the common pivot axis for all armatures is established by a resilient string in a cover plate across the larger U.

A print head for a dot matrix serial printer, including a high energy permanent magnet (13) surrounded by a plurality of coil/post combinations (15, 17) each aligned with a print hammer (23), is disclosed. The high energy permanent magnet (13) is centrally mounted on a ferromagnetic base plate (11) having a plurality of outwardly extending arms (41). A coil/post combination (15,17) is mounted on each arm (41). The coil/post combinations (15,17) are surrounded by an apertured spacer ring (19) formed on a nonmagnetic material. The hammers (23) are formed by the inwardly extending arms of a print hammer disc (21) mounted on the spacer ring (19) such that a hammer (23) is aligned with each coil/post combination (15,17). The tips of the hammers overly a stepped pole (25) mounted on the outer end of the high energy permanent magnet (13). When the coils (15) are deenergized, the magnetic flux produced by the permanent magnet (13) stresses the hammers (23) by pulling them against the tips of their related posts (17). While pulled toward the stepped pole, the hammer tips remain spaced therefrom. The hammers and the stepped pole (25) are sized, configured and positioned such that the tips of the hammers lie in the step region (109) of the stepped pole (25). As a result, magnetic flux flowing between the stepped pole (25) and the hammer tips is split between two main paths, one lying generally orthogonal to the plane of the hammers and the other lying generally coplanar with the plane of the hammers. Energization of any coil (15) by a pulse of appropriate polarity and magnitude cancels the magnetic force pulling the related hammer (23) against the related post (17), releasing the hammer (23). The stored energy created by stressing the hammer (23) causes the hammer (23) to press an associated dot printing wire (27) against a ribbon resulting in the printing of a dot on a print receiving medium. Termination of the coil energization pulse results in the hammer (23) being reattracted to its related post (17). Splitting the magnetic flux at the stepped pole (25) reduces the magnetic force at the stepped pole, allowing the hammers (23) to be more readily released.