Patent ID: 6922158

Claim:
A pressure-medium cylinder comprising a piston which has a piston rod ( 11 ), and a measuring system for determining the position of the piston rod ( 11 ) relative to a reference point, the measuring system having a code track of binary code elements ( 30 , 31 ) which code track is applied to the piston rod ( 11 ) and extends along the piston rod ( 11 ), said code elements ( 30 , 31 ) being formed by grooves ( 30 ) and plateaus ( 31 ) which run in circumferential direction in a magnetically conductive base material ( 13 ) of the piston rod ( 11 ), which base material is coated with a protective layer ( 14 ), and the measuring system having a sensor ( 20 ) which is in a fixed position relative to the reference point and has several sensor elements ( 50 ) which are arranged along the code track and each scan a limited number of code elements ( 30 , 31 ), wherein for determining the absolute position of the piston rod ( 11 ), the code elements ( 30 , 31 ) in the code track on the piston rod ( 11 ) are arranged in an irregular pattern, which for different positions of the piston rod in each case produces a unique pattern of output signals from the sensor elements ( 50 ), and wherein the grooves ( 30 ) and plateaus ( 31 ) in the piston rod form, at least in wide areas, a Manchester Code, by which at most two code elements ( 30 , 31 ) of same state follow one another.