Magnetic roller displacement sensor

The utility model belongs to the field of devices for detecting the linear displacement of objects made of magnetic material, particularly a device for detecting the displacement of a hydraulic cylinder. The utility model relates to a displacement sensor for a magnetic roller, comprising a magnetic roller, a rotary encoder and a signal processor. The excircle of the magnetic roller closely adheres to the surface of an object to be moved, the magnetic roller which is connected the rotary encoder through an input shaft can drive the rotary encoder to rotate, and the rotary encoder can send out pulse signals which can be changed into digital signals for display after being processed by the signal processor. The measuring range of the device can reach 10m and above, and the measuring resolution can be accurated to 1 mm.