Two lever print actuator with aligned pivots and energy transfer surfaces

Abstract

A two-lever electromagnetic print actuator having a pivoted bellcrank armature and an end-pivoted print hammer is urged to free-flight by energy transfer at an energy transfer contact surface. The armature pivot, print hammer pivot and energy transfer surface are aligned in sequence and substantially coplanar. This converts input energy to optimum print velocity with minimum wear. In operation, energizing a coil attracts the armature to the stator, imparting energy to an energy transfer surface on an energy transfer armature leg. The energy transfer surface moves in an arc, delivering energy to a related energy transfer surface on the print hammer. The print hammer goes into pivoted free-flight when the armature strikes a stop pad. There is mimimum sliding, and thus minimum wear, between the energy transfer surfaces of the print hammer and armature as they both move in arcs of similarly convex circles which remain tangent at their contact point. The two-lever print actuator provides a low mass print hammer with a short contact time; the hammer moves at a substantially higher velocity than the armature at the pole face due to the optimized lever length ratios.