| 摘要 |
A dot matrix printing head and related printing apparatus, the print head comprising a plurality of printing electromagnets, each having a magnetic core, an energization winding, a movable armature for actuation of a printing element and a first abutment element defining a first rest position of the armatures, where electrically energizeable means are provided for controlling the position of a second abutment element which defines a second rest position of the armatures, so as to change the air gap width between each armature and the related magnetic core and the stroke of the related printing element, depending on requirement of printing on single copy sheets or multiple copy sheets, and where, in addition to gap adjustment, the duration of the energization time interval of the printing electromagnets, their energization frequency and the advancement speed of the print head relative to a printing medium are modified to achieve the best performances, both when printing on single copy sheet and on multiple copy sheets.
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