Importance

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Abstract

A print head for dot printers comprising a plurality of actuators each including an armature supported on a holder through a torsion spring and having at its end a printing wire. The torsion spring is inserted in and bonded to the inner wall of through-holes of the bifurcated end portion of one of the armature and holder and to the inner wall of through-hole of the other of them, and has larger diameter portions fitted in the through-holes and smaller diameter portions interposed between the larger diameter portions. The smaller diameter portions of the torsion spring are formed in the concave section to avoid the concentration of torsional stress in the stepped boundary portions. Further, the opposite end portion of the other of said holder and armature made larger in thickness than the axial length of the torsion spring from the reason in strength, is forced at both end openings of the through hole with bevelling or facing portions, whereby the armature can be swung with uniform spring force of the torsion spring without being adversely affected by solder material leaked out.

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First Claim