armature having an outer end pivotably supported by the frame means an electric magnet for attracting the armature an impact dot wire being driven in an axial direction thereof by the armature the armatures are radially arranged on an arrangement face perpendicular to the direction in which the dot wires are driven and the outer end of each armature is provided with a projection protruded perpendicularly to the arrangement face and in a direction opposite to the direction in which the dot wire is driven the frame is provided with slots for loosely accommodating the projections of the respective armature so that a movement of the armature in the arrangement face is restricted application_number US 98544392 A description fig4 and 5 show an impact wire dot printing head known in the prior art the printing head comprises a plurality of e g 24 impact dot printing mechanisms radially and equi angularly arranged each of the impact dot printing mechanisms comprising an armature 51 made of a magnetic material an electromagnet 52 and a dot wire 53 the electromagnet 52 comprises an iron core 54 and a yoke 55 made of a magnetic material and cylindrically formed integrally with the iron core 54 a spring 56 urges the wire 53 toward the armature 51 the armature 51 is t shaped and has an outer end projecting toward the respective sides along an 34 arrangement face 34 an armature support ring 58 is provided with a pair of recesses 57 into which the respective outer ends of the armature 51 are loosely fit in such a manner that the armature 51 is prevented.