Magnetic sensor
An object of the present invention is to enhance detection accuracy of a magnetic sensor having four bridge-connected magnetic sensing elements. A magnetic sensor includes magnetic layers 41 - 43 provided on a surface of the sensor substrate 20 and bridge-connected magnetic sensing elements R 1 -R 4 . The magnetic layer 41 includes a main area M 1 and a converging area S 1 having a width gradually reduced with increasing distance from the main area M 1 , the magnetic layer 42 includes a main area M 2 and converging areas S 5 , S 7 each having a width gradually reduced with increasing distance from the main area M 2 , and the magnetic layer 43 includes a main area M 3 and converging areas S 6 , S 8 each having a width gradually reduced with increasing distance from the main area M 3 . The end portions of the converging areas S 1 -S 4 and the end portions of the converging areas S 5 -S 8 face each other, respectively, through gaps G 1 -G 4 , respectively. The magnetic sensing elements R 1 -R 4 are disposed on magnetic paths formed by the gaps G 1 -G 4 , respectively. According to the present invention, detection accuracy is enhanced because a magnetic flux generated by current flowing in one magnetic sensing element does not affect the other sensing element.
1. A magnetic sensor comprising:
a sensor substrate;
first, second, and third magnetic layers provided on the sensor substrate, the first magnetic layer being arranged between the second and third magnetic layers, the first magnetic layer being greater in area than the second and third magnetic layers; and
first, second, third, and fourth magnetic sensing elements that are bridge-connected,
wherein the first magnetic layer includes a first main area and first, second, third, and fourth converging areas each having a width gradually reduced with increasing distance from the first main area,
wherein the second magnetic layer includes a second main area and fifth and seventh converging areas each having a width gradually reduced with increasing distance from the second main area,
wherein the third magnetic layer includes a third main area and sixth and eighth converging areas each having a width gradually reduced with increasing distance from the third main area,
wherein end portions of the first, second, third, and fourth converging areas and end portions of the fifth, sixth, seventh, and eighth converging areas face each other, respectively, through first, second, third, and fourth gaps, respectively, and
wherein the first, second, third, and fourth magnetic sensing elements are disposed on magnetic paths formed by the first, second, third, and fourth gaps, respectively.
2. The magnetic sensor as claimed in claim 1 , further comprising a first external magnetic member provided on the sensor substrate so as to cover the first main area.
3. The magnetic sensor as claimed in claim 2 , wherein a width of the first external magnetic member in a first direction that is an extending direction of the first to fourth gaps is larger than a width of the first main area in the first direction, whereby an entire width of the first main area in the first direction is covered with the first external magnetic member.
4. The magnetic sensor as claimed in claim 2 , further comprising a second external magnetic member provided near the second main area and a third external magnetic member provided near the third main area.
5. The magnetic sensor as claimed in claim 1 ,
wherein the first converging area and the fourth converging area are line-symmetric with respect to a first line extending in a first direction that is an extending direction of the first to fourth gaps, and
the second converging area and the third converging area are line-symmetric with respect to the first line.
6. The magnetic sensor as claimed in claim 1 ,
wherein the first converging area and the third converging area are line-symmetric with respect to a second line extending in a second direction perpendicular to an extending direction of the first to fourth gaps,
wherein the second converging area and the fourth converging area are line-symmetric with respect to the second line,
wherein the fifth converging area and the seventh converging area are line-symmetric with respect to the second line, and
wherein the sixth converging area and the eighth converging area are line-symmetric with respect to the second line.
7. The magnetic sensor as claimed in claim 1 ,
wherein each of the first and third magnetic sensing elements overlaps the first and second magnetic layers, and
wherein each of the second and fourth magnetic sensing elements overlaps the first and third magnetic layers.
8. The magnetic sensor as claimed in claim 1 , wherein a cut part having a loop-shaped outer periphery is formed in the first magnetic layer.
9. The magnetic sensor as claimed in claim 1 , wherein each of the first, second, third, and fourth magnetic sensing elements is constituted by a plurality of series-connected magnetic sensing elements disposed on the magnetic path formed by each of the first, second, third, and fourth gaps.
10. The magnetic sensor as claimed in claim 9 , further comprising fourth magnetic layers disposed, in a plan view, between the plurality of magnetic sensing elements constituting each of the first, second, third, and fourth sensing elements.
11. The magnetic sensor as claimed in claim 10 , wherein the fourth magnetic layers overlap the plurality of magnetic sensing elements constituting each of the first, second, third, and fourth sensing elements.
12. The magnetic sensor as claimed in claim 10 , wherein the fourth magnetic layers are divided in a first direction that is an extending direction of the first to fourth gaps.
13. The magnetic sensor as claimed in claim 1 , wherein each of the first to fourth magnetic sensing elements is a magnetoresistive element.
14. The magnetic sensor as claimed in claim 13 , wherein sensitivity directions of the magnetoresistive elements constituting the respective first to fourth magnetic sensing elements are the same.
15. The magnetic sensor as claimed in claim 13 , wherein each of the magnetoresistive elements constituting the respective first to fourth magnetic sensing elements is a spin valve type GMR element.
16. The magnetic sensor as claimed in claim 1 ,
wherein the widths of the first and third converging areas in a first direction are gradually reduced from the first main area toward a second direction perpendicular with the first direction,
wherein the widths of the second and fourth converging areas in the first direction are gradually reduced from the first main area toward a third direction opposite to the second direction,
wherein the widths of the fifth and seventh converging areas in the first direction are gradually reduced from the second main area toward the third direction, and
wherein the widths of the sixth and eighth converging areas in the first direction are gradually reduced from the third main area toward the second direction.
17. The magnetic sensor as claimed in claim 16 , wherein the first, second, third, and fourth gaps are extending in the first direction.
18. A magnetic sensor comprising:
a sensor substrate;
first, second, and third magnetic layers provided on the sensor substrate; and
first, second, third, and fourth magnetic sensing elements that are bridge-connected,
wherein the first magnetic layer includes a first main area and first, second, third, and fourth converging areas each having a width gradually reduced with increasing distance from the first main area,
wherein the second magnetic layer includes a second main area and fifth and seventh converging areas each having a width gradually reduced with increasing distance from the second main area,
wherein the third magnetic layer includes a third main area and sixth and eighth converging areas each having a width gradually reduced with increasing distance from the third main area,
wherein end portions of the first, second, third, and fourth converging areas and end portions of the fifth, sixth, seventh, and eighth converging areas face each other, respectively, through first, second, third, and fourth gaps, respectively,
wherein the first, second, third, and fourth magnetic sensing elements are disposed on magnetic paths formed by the first, second, third, and fourth gaps, respectively,
wherein the magnetic sensor further comprises a first external magnetic member provided on the sensor substrate so as to cover the first main area, and
wherein a width of the first external magnetic member in a first direction that is an extending direction of the first to fourth gaps is larger than a width of the first main area in the first direction, whereby an entire width of the first main area in the first direction is covered with the first external magnetic member.
19. A magnetic sensor comprising:
a sensor substrate;
first, second, and third magnetic layers provided on the sensor substrate; and
first, second, third, and fourth magnetic sensing elements that are bridge-connected,
wherein the first magnetic layer includes a first main area and first, second, third, and fourth converging areas each having a width gradually reduced with increasing distance from the first main area,
wherein the second magnetic layer includes a second main area and fifth and seventh converging areas each having a width gradually reduced with increasing distance from the second main area,
wherein the third magnetic layer includes a third main area and sixth and eighth converging areas each having a width gradually reduced with increasing distance from the third main area,
wherein end portions of the first, second, third, and fourth converging areas and end portions of the fifth, sixth, seventh, and eighth converging areas face each other, respectively, through first, second, third, and fourth gaps, respectively,
wherein the first, second, third, and fourth magnetic sensing elements are disposed on magnetic paths formed by the first, second, third, and fourth gaps, respectively,
wherein the first converging area and the fourth converging area are line-symmetric with respect to a first line extending in a first direction that is an extending direction of the first to fourth gaps, and
wherein the second converging area and the third converging area are line-symmetric with respect to the first line.
20. A magnetic sensor comprising:
a sensor substrate;
first, second, and third magnetic layers provided on the sensor substrate; and
first, second, third, and fourth magnetic sensing elements that are bridge-connected,
wherein the first magnetic layer includes a first main area and first, second, third, and fourth converging areas each having a width gradually reduced with increasing distance from the first main area,
wherein the second magnetic layer includes a second main area and fifth and seventh converging areas each having a width gradually reduced with increasing distance from the second main area,
wherein the third magnetic layer includes a third main area and sixth and eighth converging areas each having a width gradually reduced with increasing distance from the third main area,
wherein end portions of the first, second, third, and fourth converging areas and end portions of the fifth, sixth, seventh, and eighth converging areas face each other, respectively, through first, second, third, and fourth gaps, respectively,
wherein the first, second, third, and fourth magnetic sensing elements are disposed on magnetic paths formed by the first, second, third, and fourth gaps, respectively,
wherein the first converging area and the third converging area are line-symmetric with respect to a second line extending in a second direction perpendicular to an extending direction of the first to fourth gaps,
wherein the second converging area and the fourth converging area are line-symmetric with respect to the second line,
wherein the fifth converging area and the seventh converging area are line-symmetric with respect to the second line, and
wherein the sixth converging area and the eighth converging area are line-symmetric with respect to the second line.