ACOUSTIC SENSOR AND ACOUSTIC SENSOR SYSTEM

• US 20150082888A1
• Filed: 08/21/2014
• 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: OTSU, Kenji, FUKUZAWA, Hideaki, HARA, Michiko, ONO, Tomio
• Granted Patent: US 9,581,571 B2
• Time in Patent Office: Days
• US Class Current: 73/587
• CPC Class Codes: G01B 7/24 using change in magnetic properties
• CPC Class Codes: G01H 11/02 by magnetic means, e.g. reluctance
• CPC Class Codes: G01N 2291/0234 Metals, e.g. steel
• CPC Class Codes: G01N 2291/0238 Wood
• CPC Class Codes: G01N 2291/0258 Structural degradation, e.g. fatigue of composites, ageing of oils
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/245 Ceramic probes, e.g. lead zirconate titanate [PZT] probes
• CPC Class Codes: G01N 29/28 providing acoustic coupling , e.g. water impedance matching G10K11/02

Abstract

According to one embodiment, an acoustic sensor includes a base and a first strain sensing element. The base includes a support and a first film unit supported by the support. The first film unit is flexible. The first strain sensing element is provided on a first surface of the first film unit. The first strain sensing element includes a first magnetic layer, a second magnetic layer, and a first intermediate layer provided between the first magnetic layer and the second magnetic layer. An angle between a magnetization of the first magnetic layer and a magnetization of the second magnetic layer is variable by an acoustic wave. The acoustic wave is transmitted to a first film unit by a first transmitting material in contact with the first film unit.

Claims

1. An acoustic sensor comprising:

a base including a support and a first film unit supported by the support, the first film unit being flexible; and

a first strain sensing element provided on a first surface of the first film unit, the first strain sensing element including a first magnetic layer, a second magnetic layer, and a first intermediate layer provided between the first magnetic layer and the second magnetic layer,

an acoustic wave being transmitted to the first film unit via a first transmitting material provided in contact with the first film unit,

an angle between a magnetization of the first magnetic layer and a magnetization of the second magnetic layer being variable in accordance with the acoustic wave.

2. The acoustic sensor according to claim 1, wherein the first transmitting material is disposed in a space partitioned by the support and the first film unit.

3. The acoustic sensor according to claim 1, further comprising a fixing unit to fix the base to a measuring object, the measuring object emitting an acoustic wave,

an acoustic impedance of the first transmitting material being lower than an acoustic impedance of the measuring object.

4. The acoustic sensor according to claim 1, further comprising:

a housing; and

a bottom plate,

the base, the first strain sensing element, and the first transmitting material being provided in the housing,

the first transmitting material being disposed between the bottom plate and the first film unit.

5. The acoustic sensor according to claim 4, further comprising an acoustic coupler material provided between the bottom plate and a measuring object.

6. The acoustic sensor according to claim 1, wherein the first transmitting material includes at least one of a liquid, a gel, and a solid.

7. The acoustic sensor according to claim 1, wherein the first transmitting material includes at least one of water, glycerin, mercury, and rubber.

8. The acoustic sensor according to claim 1, wherein the first transmitting material includes:

a first layer; and

a second layer provided between the first layer and the first film unit.

9. The acoustic sensor according to claim 1, further comprising:

a second strain sensing element; and

a second transmitting material,

the base further including a second film unit supported by the support,

the second strain sensing element being provided on a second surface of the second film unit, the second strain sensing element including a third magnetic layer, a fourth magnetic layer, and a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer,

the second transmitting material being in contact with the second film unit and configured to transmit the acoustic wave to the second film unit.

10. The acoustic sensor according to claim 9, wherein an area of the first surface is different from an area of the second surface.

11. The acoustic sensor according to claim 9, wherein a resonance frequency of the first strain sensing element is different from a resonance frequency of the second strain sensing element.

12. The acoustic sensor according to claim 1, further comprising a second strain sensing element,

the second strain sensing element being provided on the first surface, the second strain sensing element including a third magnetic layer, a fourth magnetic layer, and a second intermediate layer provided between the third magnetic layer and the fourth magnetic layer.

13. The acoustic sensor according to claim 9, further comprising a third strain sensing element,

the third strain sensing element being provided on the first surface, the third strain sensing element including a fifth magnetic layer, a sixth magnetic layer, and a third intermediate layer provided between the fifth magnetic layer and the sixth magnetic layer.

14. The acoustic sensor according to claim 1, wherein a shape of the first surface is a circle.

15. The acoustic sensor according to claim 1, wherein a shape of the first surface is a polygon.

16. The acoustic sensor according to claim 1, wherein a shape of the first surface is a rectangle.

17. The acoustic sensor according to claim 1, wherein the first surface has rounded corners.

18. The acoustic sensor according to claim 1, wherein

the first strain sensing element has a first area when projected onto the first surface, and

the first area is not more than ⅕

of an area of the first surface.

19. An acoustic sensor system comprising the acoustic sensor according to claim 1 provided in a plurality.

20. An acoustic sensor comprising:

a base including a support and a first film unit supported by the support, the first film unit being flexible;

a first strain sensing element provided on a first surface of the first film unit, the first strain sensing element including a first magnetic layer, a second magnetic layer, and a first intermediate layer provided between the first magnetic layer and the second magnetic layer; and

a first transmitting material in contact with the first film unit and configured to transmit an acoustic wave to the first film unit.