Magnetic position detection device

摘要

A distortion of a signal of a magnetic position detection device is reduced so that precise position information at a high degree of accuracy can be obtained. The magnetic position detection device 100 includes a magnetic movable body 10, a bridge circuit 20, a correction circuit 30, and a detection circuit 40. The magnetic movable body 10 is magnetized so that N-poles and S-poles alternately appear and has a region in which distances between the N-poles and the S-poles are constant. The bridge circuit 20 is formed of first, second, third, and fourth field detection portions 2R1, 2R2, 2R3, and 2R4. The correction circuit 30 is formed of fifth and sixth field detection portions 2R5 and 2R6. The detection circuit 40 detects a position of the magnetic movable body 10 on the basis of a differential output Vout of the bridge circuit.

主权项

1. A magnetic position detection device, characterized by comprising:
a magnetic movable body formed of a magnetic body, magnetized so that N-poles and S-poles alternately appear, and having a region in which distances between the N-poles and the S-poles are constant; and first through sixth field detection portions each having an electrical resistance value that varies with a change in a field in association with a movement of the magnetic movable body,wherein:
the first through sixth field detection portions are formed of magneto-resistance elements each having a spin-valve structure and including a magnetization fixed layer in which a magnetization direction with respect to an applied field is fixed, a magnetization free layer in which a magnetization direction varies with the applied field, and a non-magnetic intermediate layer sandwiched between the magnetization fixed layer and the magnetization free layer; the magneto-resistance elements forming the first through fourth field detection portions are tunneling magneto-resistance elements in which the intermediate layers are an insulator; the magnetization directions of the magnetization fixed layers of the respective magneto-resistance elements forming the first through sixth field detection portions are all in a same direction with respect to a movement direction of the magnetic movable body; the first and third field detection portions are located at a detection position in a region A; the second and fourth field detection portions are located at a detection position in a region B; the fifth field detection portion is located at a detection position in a region C; the sixth field detection portion is located at a detection position in a region D; the following relations are satisfied,
a distance L(A-B) between the detection positions in the region A and the region B with respect to a constant distance λ between an N-pole and another N-pole or between an S-pole and another S-pole of the magnetic movable body is expressed as:
L(A-B)=L=λ/n, the region C is located between the region A and the region B and a distance L(A-C) between the detection positions in the region A and the region C is expressed as:
L(A-C)=L/m=λ/(mn), andthe region D is located away from the region C in a direction of the region B and a distance L(C-D) between the detection positions in the region C and the region D is expressed as:
L(C-D)=λ/2,where n is a natural number equal to or greater than 2 and m is a natural number;
a first parallel-connected body formed of the serially-connected first and second field detection portions and the serially-connected third and fourth field detection portions and a second parallel-connected body formed of the fifth and sixth field detection portions are connected in series between a first reference potential and a second reference potential; and a signal corresponding to a movement of the magnetic movable body is outputted on the basis of a difference Vout between a midpoint potential V1 of the first and a second field detection portions and a midpoint potential V2 of the third and fourth field detection portions.