Systems for recording position information in a magnetic layer on a piston rod

摘要

Described are system for recording piston rod position information in a magnetic layer on the piston rod. A piston rod has a magnetically hard layer formed thereon to provide a recording medium. A magnetic pattern is recorded in the magnetically hard layer. A magnetic field sensor disposed adjacent to the piston rod senses the recorded magnetic pattern while the piston rod is moving and generates signals in response to the magnetic pattern that are used to determine a position of the piston rod.