To provide a device for measuring the displacement between two regions on a rotating object by a method independent of a rotational speed, and a tire circumferential force measuring sensor for measuring the force in the tire circumferential direction independently of the rotational speed.
This displacement measuring device is equipped with a magnetic element 1 for forming a magnetic field between both ends and a magnetic sensor 4 for measuring the magnetic field. The magnetic element 1 comprises a comb-shaped magnet 12 fixed on one region, and a pair of bar magnetic bodies having high permeability fixed on the other region, and the comb-shaped magnet has three magnetic poles 5A, 5B, 5C aligned at equal intervals in the prescribed direction. The three magnetic poles are directed in the direction perpendicular to the prescribed direction, and the magnetic poles on both ends have a reverse polarity to that of the center magnetic pole. The pair of bar magnetic bodies are extended in parallel with the magnetic poles and arranged respectively at the center of both poles across lines of magnetic force formed between two mutually adjacent poles among the three magnetic poles of the comb-shaped magnet in the state where the displacement is zero, and the end of each bar magnetic body on the farther side from the comb-shaped magnet is used as both ends of the magnetic element.
AOIKE YUKIO
SHIZUKU TAKAHISA
