A marking device with a reciprocating needle. The needle is attached to an armature which reciprocates in a slot in a housing by a crank which is rotated by a motor in the housing. Vibration of the motor and tolerances between the armature and track cause unwanted movements of the needle in a plane perpendicular...http://www.google.com/patents/US5551319?utm_source=gb-gplus-sharePatent US5551319 - Device for marking and article with ink
