Sensor, and method for measuring physical quantity by use of the sensor

• US 7,443,158 B2
• Filed: 09/28/2005
• Issued: 10/28/2008
• Est. Priority Date: 09/28/2004
• Status: Expired due to Fees

• Current Assignee: Yamaha Corporation
• Original Assignee: Yamaha Corporation
• Inventors: Suzuki, Tamito, Oohashi, Toshiyuki
• Primary Examiner(s): WHITTINGTON, KENNETH
• Application Number:
  US11/236,680
• Publication Number:
  US 20060066303A1
• Time in Patent Office: 1,126 Days
• Field of Search: 324/244, 324/247, 324/249, 324/251, 324/252, 324/260, 324/207.21, 324/207.26, 735/140.1, 735/141.6, 735/143.1
• US Class Current: 324/207.22
• CPC Class Codes: G01R 33/0283 in which a current or voltage is generated due to relative movement of conductor and magnetic field

Abstract

A sensor includes a first X-axis GMR element to a fourth X-axis GMR element fixed on a substrate, and a movable coil movably supported on the substrate. When electric current flows through the movable coil, a magnetic field is generated around the movable coil. The generated magnetic field is applied to the first to fourth X-axis GMR elements. The movable coil moves in accordance with acceleration generated in the sensor. The movement of the movable coil causes variation in the magnetic field applied to the first to fourth X-axis GMR element. While no electric current flows to the movable coil, the sensor measures an external magnetic field on the basis of resistances of the first to fourth X-axis GMR elements. While constant electric current flows through the movable coil, the sensor measures acceleration or the like on the basis of resistances of the first to fourth X-axis GMR elements.

Claims

1. A sensor comprising:

a substrate;

a plurality of magnetic detection elements, at least one of the magnetic detection elements being fixed on the substrate and exhibiting a characteristic value whose magnitude corresponds to a magnetic field applied thereto; and

a movable coil supported movably on the substrate via a support member and applying to the magnetic detection elements a magnetic field generated through application of electric current to the movable coil;

the sensor outputting a value corresponding to a characteristic value exhibited by at least one of the plurality of magnetic detection elements,wherein the movable coil is polygonally-shaped and at least one of the magnetic detection elements is disposed in the vicinity of central portion of one of sides of the polygon-shaped movable coil.

2. The sensor according to claim 1, further comprising electric-current control means for controlling electric current flowing through the movable coil.

3. The sensor according to claim 1, wherein at least one of the other of the magnetic detection elements is disposed in the vicinity of central portion of one of the other sides of the polygon-shaped movable coil.

4. The sensor according to claim 1, wherein at least two of the magnetic detection elements are disposed opposite to each other and the movable coil is disposed between the two of the magnetic detection elements.

5. The sensor according to claim 1, wherein the magnetic detection elements are in a full bridge connection.

6. A method for measuring a physical quantity for measuring, by use of a sensor, at least either acceleration or angular acceleration of the sensor or an object on which the sensor is fixed, the sensor including a substrate, a plurality of magnetic detection elements, at least one of the magnetic detection elements being fixed on the substrate and exhibiting a characteristic value whose magnitude corresponds to a magnetic field applied thereto, and a movable coil supported movably on the substrate via a support member, the method comprising:

applying electric current to the movable coil to generate a magnetic field, and measuring in this state a value corresponding to a characteristic value exhibited by the magnetic detection elements as at least either the acceleration or the angular acceleration, wherein the movable coil is polygonally-shaped and at least one of the magnetic detection elements is disposed in the vicinity of central portion of one of sides of the polygon-shaped movable coil.

7. The method according to claim 6, wherein at least one of the other of the magnetic detection elements is disposed in the vicinity of central portion of one of the other sides of the polygon-shaped movable coil.

8. The method according to claim 6, wherein at least two of the magnetic detection elements are disposed opposite to each other and the movable coil is disposed between the two of the magnetic detection elements.

9. The method according to claim 6, wherein the magnetic detection elements are in a full bridge connection.

10. A sensor comprising:

a substrate having a main surface;

a first magnetic detection element fixed om the main surface of the substrate so as to exhibit a characteristic value whose magnitude corresponds to a component of a magnetic field along a first direction on the main surface of the substrate;

a second magnetic detection element fixed on the main surface of the substrate so as to exhibit a characteristic value whose magnitude corresponds to a component of the magnetic field along a second direction intersecting the first direction at a predetermined angle on the main surface of the substrate; and

a movable coil supported on the substrate via a support member so as to be movable in a plane in parallel with the main surface of the substrate and applying to the first and second magnetic detection elements a magnetic field generated through application of electric current to the movable coil; and

the sensor being configured so as to output a value corresponding to a characteristic value exhibited by the first magnetic detection element and a value corresponding to a characteristic value exhibited by the second magnetic detection element.

11. The sensor according to claim 10, wherein the predetermined angle is 90 degrees.

12. The sensor according to claim 11, further comprising electric-current control means for controlling electric current flowing through the movable coil.

13. The sensor according to calim 10, further comprising electric-current control means for controlling electric current flowing through the movable coil.

14. A sensor comprising:

a substrate having a main surface;

a first magnetic detection element fixed on the main surface of the substrate; and

a second magnetic detection element fixed on the main surface of the substrate.

the sensor outputting a value to a characteristic value exhibited by the first magnetic detection element and a value corresponding to a characteristic value exhibited by the second magnetic detection element;

the first magnetic detection element being disposed in the vicinity of a central portion of a first side, which is one of the sides constituting and imaginary polygon formed on the main surface of the substrate, and being configured so as to exhibit a characteristic value whose magnitude corresponds to a component of a magnetic field along a direction perpendicularly intersecting the first side;

the second magnetic detection element being disposed in the vicinity of a central portion of a second side, which is one of sides constituting the imaginary polygon formed on the main surface of the substrate and which intersects the first side, and being configured so as to exhibit a characteristic value whose magnitude corresponds to a component of the magnetic field along a direction perpendicularly intersecting the second side; and

the sensor further comprising a movable coil having a shape identical with or similar to the imaginary polygon, the movable coil being supported on the substrate via a support member so as to be movable in a plane in parallel with the main surface of the substrate, the movable coil, at the time of the sensor being in a stationary condition, being held in its position where a barycenter of the movable coil coincides with that of the imaginary polygon and where sides of the movable coil are in parallel with those of the imaginary polygon, the movable coil applying to the first and second magnetic detection elements of a magnetic field generated through application of electric current to the movable coil.

15. The sensor according to claim 14, wherein the imaginary polygon is a regular polygon.

16. The sensor according to claim 15, wherein the imaginary polygon is a square.

17. The sensor according to claim 16, further comprising electric-current control means for controlling electric current flowing through the movable coil.

18. The sensor according to claim 15, further comprising electric-current control means for controlling electric current flowing through the movable coil.

19. The sensor according to claim 14, further comprising electric-current control means for controlling electric current flowing through the movable coil.

20. A measuring method for measuring, by use of a sensor, an external magnetic field applied to the sensor and at least either acceleration or angular acceleration of the sensor or an object on which the sensor is fixed, the sensor including a substrate, a magnetic detection element fixed on the substrate and exhibiting a characteristic value whose magnitude corresponds to a magnetic field applied thereto, and a movable coil supported movably on the substrate via a support member, the method comprising:

and external-magnetic-field-measuring step of stopping application of electric current to the movable coil so as to extinguish the magnetic field generated by the movable coil, and obtaining in this state a value corresponding to a characteristic value exhibited by the magnetic detection element as an intensity of the external magnetic field applied to the sensor; and

a physical-quantity-measuring step of applying electric current to the movable coil so as to generate the magnetic field by the movable coil, and obtaining in this state a value corresponding to a characteristic value exhibited by the magnetic detection element as at least either the acceleration or the angular acceleration.

21. The measuring method according to claim 20, wherein the external-magnetic-field-measuring step and the physical-quantity-measuring step are performed alternately and repeatedly at predetermined time intervals, and the external-magnetic-field-measuring step is started after elapse of an allowance time subsequent to stoppage of application of electric current to the movable coil upon completion of the physical-quantity-measuring step.

22. A sensor comprising:

a substrate having a main surface;

a first X-axis magnetic detection element fixed on the main surface of the substrate;

a second X-axis magnetic detection element fixed on the main surface of the substrate;

a third X-axis magnetic detection element fixed on the main surface of the substrate;

a fourth X-axis magnetic detection element fixed on the main surface of the substrate;

wherein the first X-axis magnetic detection element being disposed in the vicinity of a central portion of a first side, which is one of sides constituting an imaginary square formed on the main surface of the substrate, and being configured so as to exhibit a characteristic value whose magnitude corresponds to a component of a magnetic field along an X-axis positive direction which perpendicularly intersects the first side;

the second X-axis magnetic detection element being disposed in the vicinity of a central portion of the first side constituting the imaginary square on the main surface of the substrate, and being configured so as to exhibit a characteristic value whose magnitude corresponds to the component of the magnetic field along the X-axis positive direction;

the third X-axis magnetic detection element being disposed in the vicinity of a central portion of a second side facing the first side of the imaginary square on the main surface of the substrate, and being configured so as to exhibit a characteristic value whose magnitude corresponds to a component of the magnetic field along an X-axis negative direction which intersects the second side;

the fourth X-axis magnetic detection element being disposed in the vicinity of a central portion of the second side of the imaginary square on the main surface of the substrate, and being configured so as to exhibit a characteristic value whose magnitude corresponds to the component of the magnetic field along the X-axis negative direction; and

the sensor further comprising;

a movable coil having a shape identical with or similar to the imaginary square, the movable coil being supported on the substrate via a support member so as to be movable in a plane in parallel with the main surface of the substrate, the movable coil, at the time of the sensor being in a stationary condition, being held in its initial position where a barycenter of the movable coil coincides with that of the imaginary square and where sides of the movable coil are in parallel with those of the imaginary square, the movable coil applying to the first, second, third, and fourth magnetic detection elements a magnetic field generated through application of electric current to the movable coil.