| 摘要 |
The invention relates to a needle printing head (1) comprising a number of printing units (2). Each printing unit (2) is provided with a spring (9) supporting an armature (6) and a printing needle (10). The armature (6) is included in a magnetic field path comprising both a permanent magnet (4) and an electromagnet (7) provided with a core (8). Each spring (9) has one rigidly fastened end and one freely swinging end. According to prior art needle printing heads, the springs are so fixed that essentially the hole bending takes place in one single point in direct connection to the rigidly fastened end. This puts high requirements upon the spring material and the risk of material fatigue is great. According to the invention the bending of the spring (9) does not take place in one signal point, but it distributed along at least a first length adjacent to the fastening point. This distributed fastening is obtained by means of a supporting means (5.1) disposed on the side of the spring facing the electromagnet between the fastening point and an end of the core of the exciting coil (8) disposed in connection to the armature (6).
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