Abstract: Resiliency of a flat spring 7 corresponding to an end print wire 12 is set to be greater than that corresponding to a central print wire 12 by varying width of an effective spring portion 7b of a flat spring piece 7A to which an armature 13 is attached depending on positions of corresponding tips of the print wires 12. Distance between a magnet yoke 5 and a core 15 provided between the flat spring 7 and a permanent magnet 4 at a position corresponding to a central print wire 12 side is set to be smaller than that at a position corresponding to an end print wire 12 side by varying it depending on positions of corresponding tips of the print wires 12.

Abstract: An impact printer having a print head, the print head having a movable armature, a printing wire fixed to the armature, and sensor for detecting movement of the armature. The position of the armature is monitored based on an output of the sensor. A home sensor detects whether the print head is at a home position. A paper end sensor detect whether a printing medium is between the platen and the print head. A gap motor means adjusts a gap between the printing wire and the platen. A gap controller is responsive to detection signals output by said home sensor and said paper end sensor, for controlling the print head to swing the armature so as to cause the tip of said printing wire to strike the platen, determining a time of impact of the tip with the platen based on the monitored position of the armature, performing a comparison of the time of impact with a predetermined impact time, and outputting a drive signal to the gap motor for adjusting the gap according to a result of the comparison.

Abstract: A controller for a dot impact printer has capacitance sensors for sensing the motion of the dot wires in the print head, and a non-volatile, rewritable memory for storing self-adjustment data relating to dot-wire characteristics. A processor controls the driving of the dot wires according to the self-adjustment data stored in the memory. At certain times, the processor causes the dot wires to be driven in a test sequence and updates the self-adjustment data in the memory according to the resulting sensor output. Print quality is thereby maintained for the full guaranteed life of the print head.

Abstract: A spring charge type wire dot printing head includes front cores 35 and rear cores 36 that are disposed in circles. The front and rear cores are used in pairs, and either one of these paired cores is wound with a coil 39 or 40. Since the inductance of the coils 39 and 40 can be increased, low electric current and low electric power consumption can be realized.

Abstract: A wire-dot print head has an armature having a tip to which a print wire is secured, a core provided in confrontation with the armature, a plate spring which is supported in a cantilever fashion and to which the armature is fixed, a permanent magnet assembly generating a magnetic flux to cause the armature to be attracted toward the core overcoming the resilient force of the plate spring, and a coil wound on the core to generate a magnetic flux upon energization to cancel the magnetic flux from the permanent magnet assembly, thereby to release the armature. The permanent magnet assembly includes a first permanent magnet of the samarium-cobalt type, and a second permanent magnet of the neodyminum-iron-boron type or the lanthanoid-iron-boron type.