Patent ID: 7990139
Filing Date: 2011-08-02
Classification: G01C,G01R

Abstract:
1. A two-axis magnetic field sensor comprising: a plurality of plane coils each including a first conductor and two second conductors perpendicular to the first conductor and parallel to each other, the first conductor of a first plane coil of the plurality of plane coils being in parallel with the first conductor of a second plane coil of the plurality of plane coils, and the first conductor of a third plane coil of the plurality of plane coils being in parallel with the first conductor of a fourth plane coil of the plurality of plane coils; on a plane adjacent to the plurality of plane coils and parallel to the plurality of plane coils, a pair of first magneto-resistance elements each having a first end and a second end in a longitudinal direction, a first element of the pair of first magneto-resistance elements crossing only the first conductor of the first plane coil in the longitudinal direction of the first element of the pair of first magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the first plane coil, and a second element of the pair of first magneto-resistance elements crossing only the first conductor of the second plane coil in the longitudinal direction of the second element of the pair of first magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the second plane coil, the longitudinal directions of the pair of first magneto-resistance elements being not parallel to each other, and the first ends of the pair of first magneto-resistance elements being positioned between the first conductors of the first and second plane coils and connected to each other; a pair of second magneto-resistance elements each having a first end and a second end in a longitudinal direction, a first element of the pair of second magneto-resistance elements crossing only the first conductor of the first plane coil in the longitudinal direction of the first element of the pair of second magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the first plane coil, and a second element of the pair of second magneto-resistance elements crossing only the first conductor of the second plane coil in the longitudinal direction of the second element of the pair of second magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the second plane coil, the longitudinal directions of the pair of second magneto-resistance elements being not parallel to each other, and the first ends of the pair of second magneto-resistance elements being positioned between the first conductors of the first and second plane coils and connected to each other; a pair of third magneto-resistance elements each having a first end and a second end in a longitudinal direction, a first element of the pair of third magneto-resistance elements crossing only the first conductor of the third plane coil in the longitudinal direction of the first element of the pair of third magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the third plane coil, and a second element of the pair of third magneto-resistance elements crossing only the first conductor of the fourth plane coil in the longitudinal direction of the second element of the pair of third magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the fourth plane coil, the longitudinal directions of the pair of third magneto-resistance elements being not parallel to each other, and the first ends of the pair of third magneto-resistance elements being positioned between the first conductors of the third and fourth plane coils and connected to each other; a pair of fourth magneto-resistance elements each having a first end and a second end in a longitudinal direction, a first element of the pair of fourth magneto-resistance elements crossing only the first conductor of the third plane coil in the longitudinal direction of the first element of the pair of fourth magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the third plane coil, and a second element of the pair of fourth magneto-resistance elements crossing only the first conductor of the fourth plane coil in the longitudinal direction of the second element of the pair of fourth magneto-resistance elements at an angle of 30 degrees or more and less than 90 degrees with respect to the first conductor of the fourth plane coil, the longitudinal directions of the pair of fourth magneto-resistance elements being not parallel to each other, and the first ends of the pair of fourth magneto-resistance elements being positioned between the first conductors of the third and fourth plane coils and connected to each other; a first DC power source which supplies a current flow through the first conductor of the first plane coil so as to apply a magnetic field to saturate the two magneto-resistance elements crossing the first conductor of the first plane coil in a direction, a second DC power source which supplies a current flow through the first conductor of the second plane coil so as to apply a magnetic field to saturate the two magneto-resistance elements crossing the first conductor of the second plane coil in a direction opposite to the direction of the magnetic field saturating the two magneto-resistance elements crossing the first conductor of the first plane coil, a third DC power source which supplies a current flow through the first conductor of the third plane coil so as to apply a magnetic field to saturate the two magneto-resistance elements crossing the first conductor of the third plane coil in a direction, a fourth DC power source which supplies a current flow through the first conductor of the fourth plane coil so as to apply a magnetic field to saturate the two magneto-resistance elements crossing first conductor of the fourth plane coil in a direction opposite to the direction of the magnetic field saturating the two magneto-resistance elements crossing the first conductor of the third plane coil, and the first DC power source supplies a current flow through the first conductor of the first plane coil so as to apply to the two magneto-resistance elements crossing the first conductor of the first plane coil, a total magnetic field including a certain amount of a biasing magnetic field in a direction opposite to the magnetic field applied to saturate the two magneto-resistance elements crossing the first conductor of the first plane coil plus a magnetic field canceling an external offset magnetic field applied to the two magneto-resistance elements crossing the first conductor of the first plane coil, the second DC power source supplies a current flow through the first conductor of the second plane coil so as to apply, to the two magneto-resistance elements crossing the first conductor of the second plane coil, a total magnetic field including a certain amount of a biasing magnetic field in a direction opposite to the magnetic field applied to saturate the two magneto-resistance elements crossing the first conductor of the second plane coil plus a magnetic field canceling an external offset magnetic field applied to the two magneto-resistance elements crossing the first conductor of the second plane coil, the third DC power source supplies a current flow through the first conductor of the third plane coil so as to apply, to the two magneto-resistance elements crossing the first conductor of the third plane coil, a total magnetic field including a certain amount of a biasing magnetic field in a direction opposite to the magnetic field applied to saturate the two magneto-resistance elements crossing the first conductor of the third plane coil plus a magnetic field canceling an external offset magnetic field applied to the two magneto-resistance elements crossing the first conductor of the third plane coil, and the fourth DC power source supplies a current flow through the first conductor of the fourth plane coil so as to apply, to the two magneto-resistance elements crossing the first conductor of the fourth plane coil, a total magnetic field including a certain amount of a biasing magnetic field in a direction opposite to the magnetic field applied to saturate the two magneto-resistance elements crossing the first conductor of the fourth plane coil plus a magnetic field canceling an external offset magnetic field applied to the two magneto-resistance elements crossing the first conductor of the fourth plane coil; a measurement power source which applies a DC electric voltage for measurement: between the second ends of the pair of the first magneto-resistance elements, the second ends of the pair of the first magneto-resistance elements not positioned between the first conductors of the first and second plane coils, between the second ends of the pair of the second magneto-resistance elements, the second ends of the pair of the second magneto-resistance elements not positioned between the first conductors of the first and second plane coils, between the second ends of the pair of the third magneto-resistance elements, the second ends of the pair of the third magneto-resistance elements not positioned between the first conductors of the third and fourth plane coils, and between the second ends of the pair of the fourth magneto-resistance elements, the second ends of the pair of the fourth magneto-resistance elements not positioned between the first conductors of the third and fourth plane coils; and a device which detects a first intermediate potential output from the connected first ends of the pair of the first magneto-resistance elements and a second intermediate potential output from the connected first ends of the pair of the second magneto-resistance elements to get a first potential output difference between the first intermediate potential output and the second intermediate potential output, and which detects a third intermediate potential output from the connected first ends of the pair of the third magneto-resistance elements and a fourth intermediate potential output from the connected first ends of the pair of the fourth magneto-resistance elements to get a second potential output difference between the third intermediate potential output and the fourth intermediate potential output, while the DC electric voltage for measurement is applied to each pair of the magneto-resistance elements, and the device measures a magnetic field direction from the first potential output difference and the second potential output difference.