STRAIN SENSOR, PRESSURE SENSOR, MICROPHONE, BLOOD PRESSURESENSOR, PERSONAL DIGITAL ASSISTANT, AND HEARING AID

• US 20150082919A1
• Filed: 08/29/2014
• Published: 03/26/2015
• Est. Priority Date: 09/20/2013
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: HIGASHI, Yoshihiro, FUKUZAWA, Hideaki, FUJI, Yoshihiko, HARA, Michiko, HORI, Akio, NAGATA, Tomohiko, KII, Masayuki
• Granted Patent: US 9,383,268 B2
• Time in Patent Office: Days
• US Class Current: 73/862.69
• CPC Class Codes: G01L 1/12 by measuring variations in the magnetic properties of materials resulting from the application of stress
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182

Abstract

According to one embodiment, a strain sensor includes: a base; a strain sensing element; a magnetic field sensing element; and a processing unit. The strain sensing element includes a first magnetic layer having a first magnetization; a second magnetic layer having a second magnetization; and a first intermediate layer. In the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changes in accordance with a strain. The magnetic field sensing element includes a third magnetic layer having a third magnetization; a fourth magnetic layer having a fourth magnetization; and a second intermediate layer. In the magnetic field sensing an angle between a direction of the third magnetization and a direction of the fourth magnetization changes in accordance with a magnetic field.

Claims

1. A strain sensor comprising:

a base including a film body capable of being deformed;

a strain sensing element provided on the film body and including;

a first magnetic layer having a first magnetization;

a second magnetic layer having a second magnetization; and

a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

in the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changing in accordance with a strain;

a magnetic field sensing element provided on the base other than the film body and including;

a third magnetic layer having a third magnetization;

a fourth magnetic layer having a fourth magnetization; and

a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

in the magnetic field sensing an angle between a direction of the third magnetization and a direction of the fourth magnetization changing in accordance with a magnetic field; and

a processing unit configured to process an output signal of the strain sensing element and an output signal of the magnetic field sensing element.

2. A pressure sensor comprising a strain sensor,

the strain sensor including:

a base including a film body capable of being deformed by a pressure;

a strain sensing element provided on the film body and including;

a first magnetic layer having a first magnetization;

a second magnetic layer having a second magnetization; and

a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

in the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changing in accordance with a strain;

a magnetic field sensing element provided on the base other than the film body and including;

a third magnetic layer having a third magnetization;

a fourth magnetic layer having a fourth magnetization; and

a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

in the magnetic field sensing element an angle between a direction of the third magnetization and a direction of the fourth magnetization changing in accordance with a magnetic field; and

a processing unit configured to process an output signal of the strain sensing element and an output signal of the magnetic field sensing element.

3. The pressure sensor according to claim 2, wherein the strain sensing element further senses a magnetic field.

4. The pressure sensor according to claim 2, wherein the processing unit executes processing of subtracting an output signal of the magnetic field sensing element from an output signal of the strain sensing element.

5. The pressure sensor according to claim 2, wherein

the processing unit includes:

an intensity estimation unit that finds a correction factor on the basis of an intensity ratio between an intensity of an output signal of the strain sensing element and an intensity of an output signal of the magnetic field sensing element;

a delay estimation unit that finds a phase difference between a signal based on a partial pressure out of the pressure and a signal based on the magnetic field;

a transform unit that produces a pseudo-signal by means of an output signal of the intensity estimation unit and an output signal of the delay estimation unit;

a first differential circuit that executes processing of subtracting the pseudo-signal from an output signal of the strain sensing element; and

a second differential circuit that executes processing of subtracting an output signal of the magnetic field sensing element from an output signal of the first differential circuit.

6. The pressure sensor according to claim 5, wherein the signal based on the magnetic field is a magnetic field signal that a voice coil speaker outputs.

7. The pressure sensor according to claim 5, wherein the signal based on the partial pressure out of the pressure is an audio signal that a voice coil speaker outputs.

8. The pressure sensor according to claim 5, wherein the intensity estimation unit sets as the correction factor the minimum intensity ratio out of intensity ratios between a peak intensity of an output signal of the strain sensing element and a peak intensity of an output signal of the magnetic field sensing element.

9. The pressure sensor according to claim 5, wherein the intensity estimation unit finds the intensity ratio in a frequency band in which an intensity of an output signal of the strain sensing element and an intensity of an output signal of the magnetic field sensing element are not less than a prescribed threshold.

10. The pressure sensor according to claim 9, wherein the prescribed threshold is determined by a signal intensity not less than a sensing limit of the strain sensing element and a signal intensity not less than a sensing limit of the magnetic field sensing element.

11. The pressure sensor according to claim 2, wherein

the first magnetic layer, the first intermediate layer, and the second magnetic layer are stacked in a first stacking direction from the first magnetic layer toward the second magnetic layer,

the third magnetic layer, the second intermediate layer, and the fourth magnetic layer are stacked in a second stacking direction from the third magnetic layer toward the fourth magnetic layer,

a direction of the first magnetization is perpendicular to the first stacking direction,

a direction of the second magnetization is perpendicular to the first stacking direction,

a direction of the third magnetization is perpendicular to the second stacking direction, and

a direction of the fourth magnetization is perpendicular to the second stacking direction.

12. The pressure sensor according to claim 2, wherein

the first magnetic layer, the first intermediate layer, and the second magnetic layer are stacked in a first stacking direction from the first magnetic layer toward the second magnetic layer,

the third magnetic layer, the second intermediate layer, and the fourth magnetic layer are stacked in a second stacking direction from the third magnetic layer toward the fourth magnetic layer,

a direction of the first magnetization is parallel to the first stacking direction,

a direction of the second magnetization is parallel to the first stacking direction,

a direction of the third magnetization is parallel to the second stacking direction, and

a direction of the fourth magnetization is parallel to the second stacking direction.

13. The pressure sensor according to claim 2, wherein the strain sensing element further includes:

a first electrode having electrical conductivity;

a second electrode provided apart from the first electrode and having electrical conductivity, the first magnetic layer, the second magnetic layer, and the first intermediate layer being provided between the first electrode and the second electrode;

a buffer layer provided between the first electrode and the second magnetic layer; and

a cap layer provided between the first magnetic layer and the second electrode.

14. The pressure sensor according to claim 13, wherein the strain sensing element further includes:

a first insulating layer having an insulating property; and

a second insulating layer provided apart from the first insulating layer in a direction perpendicular to a stacking direction from the first magnetic layer toward the second magnetic layer and having an insulating property, the buffer layer, the second magnetic layer, the first intermediate layer, the first magnetic layer, and the cap layer being provided between the first insulating layer and the second insulating layer.

15. The pressure sensor according to claim 2, wherein the magnetic field sensing element further includes:

a first electrode having electrical conductivity;

a second electrode provided apart from the first electrode and having electrical conductivity, the third magnetic layer, the fourth magnetic layer, and the second intermediate layer being provided between the first electrode and the second electrode;

a buffer layer provided between the first electrode and the fourth magnetic layer; and

a cap layer provided between the third magnetic layer and the second electrode.

16. The pressure sensor according to claim 15, wherein the magnetic field sensing element further includes:

a first insulating layer having an insulating property; and

a second insulating layer provided apart from the first insulating layer in a direction perpendicular to a stacking direction from the third magnetic layer toward the fourth magnetic layer and having an insulating property, the buffer layer, the fourth magnetic layer, the second intermediate layer, the third magnetic layer, and the cap layer being provided between the first insulating layer and the second insulating layer.

17. A blood pressure sensor comprising a pressure sensor including a strain sensor,

the strain sensor including:

a base including a film body capable of being deformed by a pressure;

a strain sensing element provided on the film body and including;

a first magnetic layer having a first magnetization;

a second magnetic layer having a second magnetization; and

a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

in the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changing in accordance with a strain;

a magnetic field sensing element provided on the base other than the film body and including;

a third magnetic layer having a third magnetization;

a fourth magnetic layer having a fourth magnetization; and

a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

in the magnetic field sensing element an angle between a direction of the third magnetization and a direction of the fourth magnetization changing in accordance with a magnetic field; and

a processing unit configured to process an output signal of the strain sensing element and an output signal of the magnetic field sensing element.

18. A microphone comprising a pressure sensor including a strain sensor,

the strain sensor including:

a base including a film body capable of being deformed by a pressure;

a strain sensing element provided on the film body and including;

a first magnetic layer having a first magnetization;

a second magnetic layer having a second magnetization; and

a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

in the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changing in accordance with a strain;

a magnetic field sensing element provided on the base other than the film body and including;

a third magnetic layer having a third magnetization;

a fourth magnetic layer having a fourth magnetization; and

a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

in the magnetic field sensing element an angle between a direction of the third magnetization and a direction of the fourth magnetization changing in accordance with a magnetic field; and

a processing unit configured to process an output signal of the strain sensing element and an output signal of the magnetic field sensing element.

19. A personal digital assistant comprising a microphone including a pressure sensor,

the pressure sensor including a strain sensor,

the strain sensor including:

a base including a film body capable of being deformed by a pressure;

a strain sensing element provided on the film body and including;

a first magnetic layer having a first magnetization;

a second magnetic layer having a second magnetization; and

a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

in the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changing in accordance with a strain;

a magnetic field sensing element provided on the base other than the film body and including;

a third magnetic layer having a third magnetization;

a fourth magnetic layer having a fourth magnetization; and

a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

in the magnetic field sensing element an angle between a direction of the third magnetization and a direction of the fourth magnetization changing in accordance with a magnetic field; and

a processing unit configured to process an output signal of the strain sensing element and an output signal of the magnetic field sensing element.

20. A hearing aid comprising a microphone including a pressure sensor,

the pressure sensor including a strain sensor,

the strain sensor including:

a base including a film body capable of being deformed by a pressure;

a strain sensing element provided on the film body and including;

a first magnetic layer having a first magnetization;

a second magnetic layer having a second magnetization; and

a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

in the strain sensing element an angle between a direction of the first magnetization and a direction of the second magnetization changing in accordance with a strain;

a magnetic field sensing element provided on the base other than the film body and including;

a third magnetic layer having a third magnetization;

a fourth magnetic layer having a fourth magnetization; and

a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

in the magnetic field sensing element an angle between a direction of the third magnetization and a direction of the fourth magnetization changing in accordance with a magnetic field; and

a processing unit configured to process an output signal of the strain sensing element and an output signal of the magnetic field sensing element.