Magnetic field measuring device

• US 9,581,426 B2
• Filed: 07/27/2012
• Issued: 02/28/2017
• Est. Priority Date: 07/29/2011
• Status: Active Grant

• Current Assignee: Asahi Kasei Microdevices Corporation (Asahi Kasei Corporation)
• Original Assignee: Asahi Kasei Microdevices Corporation (Asahi Kasei Corporation)
• Inventors: Okamoto, Junichiro, Takahashi, Arata
• Primary Examiner(s): Bui, Bryan
• Application Number:
  US14/233,411
• Publication Number:
  US 20140156220A1
• Time in Patent Office: 1,677 Days
• Field of Search: 702/150
• US Class Current: 1/1
• CPC Class Codes: G01B 7/14 for measuring distance or clearance between spaced objects or spaced apertures G01B7/30 takes precedence
• CPC Class Codes: G01D 2205/40 Position sensors comprising arrangements for concentrating or redirecting magnetic flux
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01D 5/2451 Incremental encoders G01D5/2454 takes precedence
• CPC Class Codes: G01R 33/072 Constructional adaptation of the sensor to specific applications

Abstract

The present invention provides a magnetic field measuring device comprising first to fourth magnetoelectric transducers, magnetic convergence plates, and a calculation unit that calculates the strength of a magnetic field applied in a horizontal direction and/or a vertical direction with respect to a magneto-sensing surface of the magnetoelectric transducers, wherein the magnetic convergence plates are placed in the vicinity of the first to fourth magnetoelectric transducers so as to convert magnetic field vectors, and the calculation unit includes a first calculation block that adds or subtracts output from the first to fourth magnetoelectric transducers, and outputs a calculation result.

Claims

1. A magnetic field measuring device that detects the strength of a magnetic field produced from a magnetic field-producing body, comprising:

first to fourth magnetoelectric transducers;

magnetic convergence plates made up of a magnetic body; and

a calculation unit that calculates the strength of a magnetic field applied in a horizontal direction and/or a vertical direction with respect to a magneto-sensing surface of the magnetoelectric transducers;

wherein the magnetic convergence plates are placed in the vicinity of the first to fourth magnetoelectric transducers so as to

convert magnetic field vectors produced in a horizontal direction with respect to the magneto-sensing surface of the first magnetoelectric transducer and the magneto-sensing surface of the second magnetoelectric transducer into magnetic field vectors in a vertical direction with respect to the magneto-sensing surface of the first magnetoelectric transducer and the magneto-sensing surface of the second magnetoelectric transducer, and also in opposite directions at the respective magneto-sensing surfaces, and further,

convert magnetic field vectors produced in a horizontal direction with respect to the magneto-sensing surface of the third magnetoelectric transducer and the magneto-sensing surface of the fourth magnetoelectric transducer into magnetic field vectors in a vertical direction with respect to the magneto-sensing surface of the third magnetoelectric transducer and the magneto-sensing surface of the fourth magnetoelectric transducer, and also in opposite directions at the respective magneto-sensing surfaces, and

wherein the calculation unit comprises a first calculation block that adds or subtracts outputs from the first to fourth magnetoelectric transducers to output a calculation result.

3. The magnetic field measuring device according to claim 1, wherein the first calculation block comprises a first addition/subtraction block that adds or subtracts outputs from the first magnetoelectric transducer and the second magnetoelectric transducer to output a calculation result, a second addition/subtraction block that adds or subtracts outputs from the third magnetoelectric transducer and the fourth magnetoelectric transducer to output a calculation result, and a third addition/subtraction block that adds or subtracts output from the first addition/subtraction block and output from the second addition/subtraction block to output a calculation result.

4. The magnetic field measuring device according to claim 1, wherein the first calculation block comprises a first addition/subtraction block that adds or subtracts outputs from the first magnetoelectric transducer and the third magnetoelectric transducer to output a calculation result, a second addition/subtraction block that adds or subtracts outputs from the second magnetoelectric transducer and the fourth magnetoelectric transducer to output a calculation result, and a third addition/subtraction block that adds or subtracts output from the first addition/subtraction block and output from the second addition/subtraction block to output a calculation result.

5. The magnetic field measuring device according to claim 1, wherein the calculation unit comprises a second calculation block that adds or subtracts outputs from the first to fourth magnetoelectric transducers to calculate a signal whose phase differs from an output signal of the first calculation block.

6. The magnetic field measuring device according to claim 5, wherein the phase difference between an output signal from the first calculation block and an output signal from the second calculation block is 90 degrees.

7. The magnetic field measuring device according to claim 5, wherein the second calculation block comprises a fourth addition/subtraction block that adds or subtracts outputs from the first magnetoelectric transducer and the second magnetoelectric transducer to output a calculation result, a fifth addition/subtraction block that adds or subtracts outputs from the third magnetoelectric transducer and the fourth magnetoelectric transducer to output a calculation result, and a sixth addition/subtraction block that adds or subtracts output from the fourth addition/subtraction block and output from the fifth addition/subtraction block to output a calculation result.

8. The magnetic field measuring device according to claim 5, wherein the second calculation block comprises a fourth addition/subtraction block that adds or subtracts outputs from the first magnetoelectric transducer and the third magnetoelectric transducer to output a calculation result, a fifth addition/subtraction block that adds or subtracts outputs from the second magnetoelectric transducer and the fourth magnetoelectric transducer to outputs a calculation result, and a sixth addition/subtraction block that adds or subtracts output from the fourth addition/subtraction block and output from the fifth addition/subtraction block to output a calculation result.

9. The magnetic field measuring device according to claim 1, wherein the first to fourth magnetoelectric transducers are placed approximately linearly.

10. The magnetic field measuring device according to claim 1, wherein the calculation unit detects position, move, or rotation of the magnetic field-producing body.

11. The magnetic field measuring device according to claim 10, wherein the calculation unit detects position, move, or rotation of the magnetic field-producing body, on the basis of output from the first calculation block.

12. The magnetic field measuring device according to claim 10, wherein the calculation unit detects position, move, or rotation of the magnetic field-producing body, on the basis of a signal obtained by forming an output signal from the first calculation block into a pulse waveform.

13. The magnetic field measuring device according to claim 5, wherein the calculation unit detects position, move, or rotation of the magnetic field-producing body, on the basis of output from the first calculation block, and output from the second calculation block.

14. The magnetic field measuring device according to claim 1, comprising:

a magnetic field-producing body;

wherein the magnetic field-producing body is a movable and/or rotatable multipolar-magnetized magnet, or alternatively, a structure composed of a back-bias magnet installed in the vicinity of the first to fourth magnetoelectric transducers, and movable and/or rotatable gear teeth.

15. The magnetic field measuring device according to claim 1, comprising:

a magnetic field-producing body;

wherein the magnetic field-producing body is a structure composed of a back-bias magnet installed in the vicinity of the first to fourth magnetoelectric transducers, and movable and/or rotatable gear teeth, and

the first to fourth magnetoelectric transducers are installed at positions between the back-bias magnet and the gear teeth.

2. A magnetic field measuring device that detects the strength of a magnetic field produced from a magnetic field-producing body, comprising:

first to fourth magnetoelectric transducers; and

a calculation unit that calculates the strength of a magnetic field applied in a horizontal direction and/or a vertical direction with respect to a magneto-sensing surface of the magnetoelectric transducers;

wherein the calculation unit comprises;

a first calculation block that adds or subtracts outputs from the first to fourth magnetoelectric transducers to output a calculation result, and

a second calculation block that adds or subtracts output from the first to fourth magnetoelectric transducers to calculate a signal whose phase differs by 90 degrees from an output signal of the first calculation block to output a calculation result.