Needle type printing mechanism electromagnet - has spring-loaded plunger sliding between end cap and core in former

摘要

The electromagnetic control unit is for a neelde-type matrix printing mechanism. It has a coil wound on a cylindrical former (21) and a stationary magnetic core (13) with a cylindrical portion (27) inserted in a central bore (23) of the former from the front. A plunger (16) slides in this bore, and an end cap (17) secured to the former has a portion (44) opposite the plunger rear end, which is spring-loaded against it (50). This leaves a gap of set length between plunger and core. A yoke (12), acting as a housing, forms a magnetic circuit from core to plunger when the coil is energised, and a printing needle (15) passes through a central opening in the core and is fixed to the plunger at its rear end.