Pressure sensor and microphone

• US 8,973,446 B2
• Filed: 12/28/2012
• Issued: 03/10/2015
• Est. Priority Date: 03/29/2012
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Fukuzawa, Hideaki, Enamito, Akihiko, Nishimura, Osamu, Hara, Michiko, Yuasa, Hiromi, Fuji, Yoshihiko, Kii, Masayuki, Fujisawa, Eizo
• Primary Examiner(s): Noori, Max
• Application Number:
  US13/730,016
• Publication Number:
  US 20130255393A1
• Time in Patent Office: 802 Days
• Field of Search: 737/60, 737/79, 738/626.9, 73862331-861335
• US Class Current: 73/779
• CPC Class Codes: G01L 1/12 by measuring variations in the magnetic properties of materials resulting from the application of stress
• CPC Class Codes: G01L 1/125 by using magnetostrictive means magnetostrictive sensors H10N35/101
• CPC Class Codes: G01L 9/005 Non square semiconductive diaphragm
• CPC Class Codes: G01L 9/008 using piezoelectric devices piezoelectric resonators G01L9/0022; surface acoustic waves G01L9/0025
• CPC Class Codes: G01L 9/16 by making use of variations in the magnetic properties of material resulting from the application of stress

Abstract

According to one embodiment, a pressure sensor includes a base, and a first sensor unit. The first sensor unit includes a first transducer thin film, a first strain sensing device and a second strain sensing device. The first strain sensing device includes a first magnetic layer, a second magnetic layer, and a first intermediate layer provided between the first and the second magnetic layers. The second strain sensing device is provided apart from the first strain sensing device on the first membrane surface and provided at a location different from a location of the barycenter, the second strain sensing device including a third magnetic layer, a fourth magnetic layer, and a second intermediate layer provided between the third and the fourth magnetic layers, the first and the second intermediate layers being nonmagnetic. The first and the second strain sensing devices, and the barycenter are in a straight line.

Claims

1. A pressure sensor comprising:

a base; and

a first sensor unit provided on the base,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

the second strain sensing device being disposed between the first strain sensing device and the barycenter.

2. The sensor according to claim 1, wherein the first sensor unit further includes a fixing unit connected to an edge portion of the first transducer thin film and configured to fix the edge portion to the base.

3. The sensor according to claim 2, wherein the fixing unit fixes a part of the edge portion of the first transducer thin film to the base, and the part is located in a straight line passing the first strain sensing device, the second strain sensing device and the barycenter.

4. The sensor according to claim 2, wherein the fixing unit continuously fixes the edge portion of the first transducer thin film to the base.

5. The sensor according to claim 1, wherein the second strain sensing device and the first strain sensing device are arranged along an edge portion of the first membrane surface.

6. The sensor according to claim 1, wherein

a magnetization direction of the third magnetic layer is along one of a magnetization direction of the first magnetic layer and a magnetization direction of the second magnetic layer, and

a magnetization direction of the fourth magnetic layer is along the other of the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer.

7. The sensor according to claim 1, further comprising a processing circuit configured to process a first signal obtained from the first strain sensing device and a second signal obtained from the second strain sensing device.

8. The sensor according to claim 7, wherein the processing circuit is configured to perform at least one of an adding process of the first signal and the second signal, a subtracting process of the first signal and the second signal, and a multiplying process of the first signal and the second signal.

9. The sensor according to claim 1, wherein

a length of the first strain sensing device along a direction perpendicular to a direction from the first magnetic layer toward the second magnetic layer is 0.5 μ

m or more and 20 μ

m or less, and

a length of the second strain sensing device along a direction perpendicular to the direction from the first magnetic layer toward the second magnetic layer is 0.5 μ

m or more and 20 μ

m or less.

10. The sensor according to claim 1, further comprising a second sensor unit provided at a location on the base different from a location of the first sensor unit,

the second sensor unit including:

a second transducer thin film having a second membrane surface, the second transducer thin film being flexible; and

a third strain sensing device provided on the second membrane surface, the third strain sensing device 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, the third intermediate layer being nonmagnetic,

a width of the second transducer thin film passing through a barycenter of the second membrane surface of the second transducer thin film along a direction parallel with the second membrane surface being different from a width of the first transducer thin film passing through the barycenter of the first membrane surface of the first transducer thin film along a direction parallel with the first membrane surface.

11. The sensor according to claim 1, wherein

the first sensor unit further includes

a third strain sensing device provided at a location on the first membrane surface different from the location of the barycenter of the first membrane surface, the third strain sensing device 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, the third intermediate layer being nonmagnetic;

and

a fourth strain sensing device provided apart from the third strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the fourth strain sensing device including a seventh magnetic layer, an eighth magnetic layer, and a fourth intermediate layer provided between the seventh magnetic layer and the eighth magnetic layer, the fourth intermediate layer being nonmagnetic,

the fourth strain sensing device is disposed between the third strain sensing device and the barycenter,

a straight line passing the first strain sensing device and the barycenter crosses a straight line passing the third strain sensing device and the barycenter.

12. A pressure sensor comprising:

a base;

a first sensor unit provided on the base; and

a processing circuit,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

a distance between the first strain sensing device and the barycenter being the same as a distance between the second strain sensing device and the barycenter,

a first straight line passing the first strain sensing device and the barycenter being oblique with respect to the a second straight line passing the second strain sensing and the barycenter,

a magnetization direction of the third magnetic layer being along one of a magnetization direction of the first magnetic layer and a magnetization direction of the second magnetic layer,

a magnetization direction of the fourth magnetic layer being along the other of the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer,

the processing circuit being configured to process a first signal obtained from the first strain sensing device and a second signal obtained from the second strain sensing device, and

the processing circuit being configured to perform at least one of an adding process of the first signal and the second signal, a subtracting process of the first signal and the second signal, and a multiplying process of the first signal and the second signal.

13. The sensor according to claim 12, wherein the first sensor unit further includes a fixing unit connected to an edge portion of the first transducer thin film and configured to fix the edge portion to the base.

14. The sensor according to claim 13, wherein the fixing unit fixes a plurality of portions of the edge portion of the first transducer thin film to the base, the portions being symmetric to the barycenter.

15. The sensor according to claim 13, wherein the fixing unit continuously fixes the edge portion of the first transducer thin film to the base.

16. The sensor according to claim 12, wherein the second strain sensing device and the first strain sensing device are arranged along an edge portion of the first membrane surface.

17. The sensor according to claim 12, wherein

a length of the first strain sensing device along a direction perpendicular to a direction from the first magnetic layer toward the second magnetic layer is 0.5 μ

m or more and 20 μ

m or less, and

a length of the second strain sensing device along a direction perpendicular to the direction from the first magnetic layer toward the second magnetic layer is 0.5 μ

m or more and 20 μ

m or less.

18. The sensor according to claim 12, further comprising a second sensor unit provided at a location on the base different from a location of the first sensor unit,

the second sensor unit including:

a second transducer thin film having a second membrane surface, the second transducer thin film being flexible; and

a third strain sensing device provided on the second membrane surface, the third strain sensing device 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, the third intermediate layer being nonmagnetic,

a width of the second transducer thin film passing through a barycenter of the second membrane surface of the second transducer thin film along a direction parallel with the second membrane surface being different from a width of the first transducer thin film passing through the barycenter of the first membrane surface of the first transducer thin film along a direction parallel with the first membrane surface.

19. A pressure sensor comprising:

a base;

a first sensor unit provided on the base; and

a processing circuit,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

the processing circuit being configured to process a first signal obtained from the first strain sensing device and a second signal obtained from the second strain sensing device, and

the processing circuit being configured to perform at least one of an adding process of the first signal and the second signal, a subtracting process of the first signal and the second signal, and a multiplying process of the first signal and the second signal.

20. The sensor according to claim 19, wherein the first sensor unit further includes a fixing unit connected to an edge portion of the first transducer thin film and configured to fix the edge portion to the base.

21. The sensor according to claim 20, wherein the fixing unit fixes a part of the edge portion of the first transducer thin film to the base and the part is located in a straight line passing the first strain sensing device, the second strain sensing device and the barycenter.

22. The sensor according to claim 20, wherein the fixing unit continuously fixes the edge portion of the first transducer thin film to the base.

23. The sensor according to claim 19, wherein the second strain sensing device and the first strain sensing device are arranged along an edge portion of the first membrane surface.

24. The sensor according to claim 19, wherein

a magnetization direction of the third magnetic layer is along one of a magnetization direction of the first magnetic layer and a magnetization direction of the second magnetic layer, and

a magnetization direction of the fourth magnetic layer is along the other of the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer.

25. The sensor according to claim 19, wherein

a length of the first strain sensing device along a direction perpendicular to a direction from the first magnetic layer toward the second magnetic layer is 0.5 μ

m or more and 20 μ

m or less, and

a length of the second strain sensing device along a direction perpendicular to the direction from the first magnetic layer toward the second magnetic layer is 0.5 μ

m or more and 20 μ

m or less.

26. The sensor according to claim 19, further comprising a second sensor unit provided at a location on the base different from a location of the first sensor unit,

the second sensor unit including:

a second transducer thin film having a second membrane surface, the second transducer thin film being flexible; and

a third strain sensing device provided on the second membrane surface, the third strain sensing device 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, the third intermediate layer being nonmagnetic,

a width of the second transducer thin film passing through a barycenter of the second membrane surface of the second transducer thin film along a direction parallel with the second membrane surface being different from a width of the first transducer thin film passing through the barycenter of the first membrane surface of the first transducer thin film along a direction parallel with the first membrane surface.

27. A microphone comprising a pressure sensor including:

a base; and

a first sensor unit provided on the base,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

the second strain sensing device being disposed between the first strain sensing device and the barycenter.

28. A microphone comprising a pressure sensor including:

a base;

a first sensor unit provided on the base; and

a processing circuit,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

a distance between the first strain sensing device and the barycenter being the same as a distance between the second strain sensing device and the barycenter,

a first straight line passing the first strain sensing device and the barycenter being oblique with respect to the a second straight line passing the second strain sensing device and the barycenter,

a magnetization direction of the third magnetic layer being along one of a magnetization direction of the first magnetic layer and a magnetization direction of the second magnetic layer,

a magnetization direction of the fourth magnetic layer being along the other of the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer,

the processing circuit being configured to process a first signal obtained from the first strain sensing device and a second signal obtained from the second strain sensing device, and

the processing circuit being configured to perform at least one of an adding process of the first signal and the second signal, a subtracting process of the first signal and the second signal, and a multiplying process of the first signal and the second signal.

29. A microphone comprising a pressure sensor including:

a base;

a first sensor unit provided on the base; and

a processing circuit,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

the processing circuit being configured to process a first signal obtained from the first strain sensing device and a second signal obtained from the second strain sensing device, and

the processing circuit being configured to perform at least one of an adding process of the first signal and the second signal, a subtracting process of the first signal and the second signal, and a multiplying process of the first signal and the second signal.

30. A pressure sensor comprising:

a base; and

a first sensor unit provided on the base,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

the second strain sensing device being disposed between the first strain sensing device and the barycenter,

wherein the first sensor unit further includes a fixing unit connected to an edge portion of the first transducer thin film and configured to fix the edge portion to the base, and

the fixing unit continuously fixes the edge portion of the first transducer thin film to the base.

31. A pressure sensor comprising:

a base; and

a first sensor unit provided on the base,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

a distance between the first strain sensing device and the barycenter being the same as a distance between the second strain sensing device and the barycenter,

wherein the first sensor unit further includes a fixing unit connected to an edge portion of the first transducer thin film and configured to fix the edge portion to the base, and

the fixing unit continuously fixes the edge portion of the first transducer thin film to the base.

32. A pressure sensor comprising:

a base;

a first sensor unit provided on the base; and

a processing circuit,

the first sensor unit including;

a first transducer thin film having a first membrane surface, the first transducer thin film being flexible;

a first strain sensing device provided at a location on the first membrane surface different from a location of a barycenter of the first membrane surface, the first strain sensing device 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, the first intermediate layer being nonmagnetic; and

a second strain sensing device provided apart from the first strain sensing device on the first membrane surface and provided at a location different from the location of the barycenter, the second strain sensing device 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 intermediate layer being nonmagnetic,

the processing circuit being configured to process a first signal obtained from the first strain sensing device and a second signal obtained from the second strain sensing device, and

the processing circuit being configured to perform at least one of an adding process of the first signal and the second signal, a subtracting process of the first signal and the second signal, and a multiplying process of the first signal and the second signal,

wherein the first sensor unit further includes a fixing unit connected to an edge portion of the first transducer thin film and configured to fix the edge portion to the base, and

wherein the fixing unit continuously fixes the edge portion of the first transducer thin film to the base.