Magnetic position detection device

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 twelfth 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 twelfth 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 and the magneto-resistance elements forming the seventh through tenth 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 twelfth 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 seventh and ninth field detection portions are located at a detection position in a region E;
• the eighth and tenth field detection portions are located at a detection position in a region F;
• the eleventh field detection portion is located at a detection position in a region G;
• the twelfth field detection portion is located at a detection position in a region H;
• 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)=L1=λ/n1,
• 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)=L1/m1=λ/(m1n1),
• the 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,
• the region E is located away from the region A in the direction of the region B and a distance L(A-E) between the detection positions in the region A and the region E is expressed as:
• L(A-E)=L2=λ/n2,
• the region F is located away from the region E in a direction of the region D and a distance L(E-F) between the detection positions in the region E and the region F is expressed as:
• L(E-F)=L1=λ/n1,
• the region G is located between the region E and the region F and a distance L(E-G) between the detection positions in the region E and the region G is expressed as:
• L(E-G)=L1/m2=a/(m2n1), and
• the region H is located away from the region G in a direction of the region F and a distance L(G-H) between the detection positions in the region G and the region H is expressed as:
• L(G-H)=λ/2,
• where n1 and n2 are natural numbers equal to or greater than 2 and m1 and m2 are natural numbers;
• 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;
• a third parallel-connected body formed of the serially-connected seventh and eighth field detection portions and the serially-connected ninth and tenth field detection portions and a fourth parallel-connected body formed of the eleventh and twelfth field detection portions are connected in series between a third reference potential and a fourth reference potential;
• and
• a signal corresponding to a movement of the magnetic movable body is outputted based on a difference Vout between a difference V12, which is a difference between a midpoint potential V1 of the first and second field detection portions and a midpoint potential V2 of the third and fourth field detection portions, and a difference V34, which is a difference between a midpoint potential V3 of the seventh and eighth field detection portions and a midpoint potential V4 of the ninth and tenth field detection portions.