High speed printer printing hammer mechanism - uses rotating magnetic strip at gap between electromagnets and permanent magnets to improve action

摘要

The printing hammer operating system for a high speed printer, uses arms (11) each swinging about an axis (9) and with a printing head (2) at the top, and a magnet (5) at the bottom. Attached to the lower part of the arm is a spring (3) tending to hold the head in cotact. In front of each arm is a magnet (6) with an exitation coil (8) around it, which can swing the arm in the opposite direction. Below the arms is a rotating shaft (11) with a layer of magnetic material around it and an outer layer of soft iron carrying a flat strip (10) with slots opposite the hammer arms. The magnetic force of the strip acts while approaching and passing the gap between the magnetic surface (7) of the electromagnet (6) and the permanent magnet (5) assisting their action. The magnet are made of rare earth elements.