| 摘要 |
PURPOSE:To suppress the warpage of an armature by a drive force at the time of striking a wire and to prevent the armature from vibrating due to the warpage by forming the armature in a plate state of the entirely warped shape in which its center protrudes in the drive force acting direction at the time of striking. CONSTITUTION:An armature 15 is so formed in shape of substantially triangular plate state in which the whole is warped in a circular arc state with radius R of curvature that its center protrudes in a direction of a magnetic force F acting as a drive force at the time of striking a wire 2. Then, the armature 15 is brought at the sections of points E, F into contact with the edges of the hole 13b of an auxiliary yoke 13 to reduce the warpage of the armature 15 by the force F. As a result, it can prevent the secondary vibration of the armature 15 due to the warpage. |
