| 摘要 |
PURPOSE:To prevent a retainer from fatigue fracture and elongate the service life of the printing head by a method wherein the contact part between an armature and the retainer has a point contact structure. CONSTITUTION:An angular projecting part 4' is provided near the center of the engaging part of an armature hinge guide part 7 for engagement with the armature 3, so that the projecting part 4' contacts with the armature 3 and supports the latter. The height of the projecting part 4' is set to be larger than the maximum amplitude of torsion created when the armature 3 is attracted, so that the upward force applied from the armature 3 to the hinge guide part 7 is borne by the projecting part 4' and the impact generated at the time of re-collision of the armature hinge guide part 7 against the armature 3 is also borne by the projecting part 4'. Accordingly, the concentration of strss on the vicinity of the corner parts 8 is avoided and the deformation of the corner parts 8 is minimized. |
