Wire dot printer head and wire dot printer using the same

A wire dot printer, comprising:

• a sheet transferring passage for guiding a sheet;
• transferring rollers for transferring the sheet in the sheet transferring passage;
• a platen arranged along the sheet transferring passage;
• a wire dot printer head;
• comprising
• a yoke;
• a plurality of cores arranged in an annular form on the yoke;
• a plurality of coils combined with the cores so as to fit the cores;
• a plurality of armatures supported so as to be raised or lowered in respect to the cores;
• a plurality of wires supported at the free ends of the armatures in such a way that they may be driven and displaced;
• and
• an extremity end guide having a plurality of guide holes for independently and slidably supporting the extremity ends of the wires and arranging them,
• wherein, the guide holes of the extremity end guide form one or more groups, the extremity end guide holes in each of the groups are set such that a plurality of wires having rear ends adjacent to each other within a certain range are applied as one sub-group, the wires are classified into a plurality of sub-groups, the extremity ends of the wires are arranged in a unit of sub group on a straight line in the sub-scanning direction, and the arrangement positions of the extremity ends of the wires in the main scanning direction are made different in response to a difference in the arrangement positions of the rear ends of the wires for every sub-groups different in such a way that the bending stress of the corresponding wire may become low as compared with that where the extremity ends of all the wires are arranged on the straight line.
• wherein the wire dot printer head is faced against the platen through the sheet transferring passage and movably held in the width direction of the sheet transferring passage;
• and
• means for performing a voltage application to the coils driving respective wires in response to the arrangement positions of the extremity ends of the wires in the main scanning direction while changing timing therefor.