System and method for reducing effect of magnetic fields on a magnetic transducer

• US 20050001703A1
• Filed: 06/25/2004
• Published: 01/06/2005
• Est. Priority Date: 04/01/2002
• Status: Active Grant

• Current Assignee: MED-EL Elektromedizinische Gerate GmbH (MED-EL Corporation)
• Original Assignee: MED-EL Elektromedizinische Gerate GmbH (MED-EL Corporation)
• Inventors: Zimmerling, Martin
• Granted Patent: US 7,190,247 B2
• Time in Patent Office: Days
• US Class Current: 335/220
• CPC Class Codes: B06B 1/045 using vibrating magnet, armature or coil system
• CPC Class Codes: H01H 36/0073 actuated by relative movement between two magnets
• CPC Class Codes: H02K 33/16 with polarised armatures moving in alternate directions by reversal or energisation of a single coil system
• CPC Class Codes: H02K 35/02 with moving magnets and stationary coil systems
• CPC Class Codes: H04R 11/00 Transducers of moving-armature or moving-core type acoustic diaphragm of magnetisable material directly coacting with electromagnet H04R13/00
• CPC Class Codes: H04R 25/606 acting directly on the eardrum, the ossicles or the skull, e.g. mastoid, tooth, maxillary or mandibular bone, or mechanically stimulating the cochlea, e.g. at the oval window

Abstract

An electromagnetic driver transducer free of torque in the presence of an external magnetic field, of any direction and orientation (such as in a Magnetic Resonance Imaging environment). The transducer includes a housing. At least one coil is associated with the housing. A plurality of magnets within the housing are aligned along an axis in an anti-parallel orientation. The magnets are free to move along an axis, wherein vibration of the magnets causes vibration of the housing. The transducer may be, for example, fixed to an ossicle.

Claims

1. An electromagnetic transducer comprising:

a housing;

at least one coil associated with the housing; and

a plurality of magnets within the housing, the magnets aligned along an axis in an anti-parallel orientation, the magnets free to move along the axis, wherein vibration of the magnets causes vibration of the housing.

2. The electromagnetic transducer according to claim 1, further comprising at least one biasing member positioned between one of the magnets and the housing, the biasing member for biasing movement of the magnets.

3. The electromagnetic transducer according to claim 2, wherein the at least one biasing member is flexible and resilient.

4. The electromagnetic transducer according to claim 2, wherein the at least one biasing member includes one of a spring and a silicone material.

5. The electro-magnetic transducer according to claim 2, wherein the at least one biasing member prevents the magnets from directly contacting the housing.

6. The electromagnetic transducer according to claim 1, wherein the transducer is substantially free of torque in the presence of an external magnetic field.

7. The electromagnetic transducer according to claim 6, wherein the external magnetic field is caused by a Magnetic Resonance Imaging device.

8. The electromagnetic transducer according to claim 1, wherein the housing is adapted to be fixed to an ossicle.

9. The electromagnetic transducer according to claim 1, wherein the at least one coil is positioned within the housing.

10. The electromagnetic transducer according to claim 1, wherein the at least one coil is positioned external to the housing.

11. The electromagnetic transducer according to claim 1, wherein the magnets include a first magnet having a first pole and a second magnet having a second pole, the first pole and the second pole having similar orientation, the first and second magnets aligned such that the first pole and the second pole are adjacent.

12. The electro-magnetic transducer according to claim 1, wherein the magnets are cylindrical.

13. The electromagnetic transducer according to claim 1, wherein at least one of the magnets and an inner wall of the housing are coated with a material having a low coefficient of friction.

14. The electromagnetic transducer according to claim 1, wherein the material is Teflon.

15. The electromagnetic transducer according to claim 1, wherein the friction of the magnet is reduced by a lubricant.

16. The electromagnetic transducer according to claim 1, wherein the at least one coil includes a plurality of coils, wherein the induced voltage of the plurality of coils arising from an external RF field is zero.

17. The electromagnetic transducer according to claim 16, wherein the at least one coil includes a first and second outer coil, and a middle coil positioned between the first and second outer coils, wherein the middle coil is winded in a direction opposite the two outer coils, and wherein the number of loops of the middle coil equals the sum of loops of the first and second outer coils.

18. The electromagnetic transducer according to claim 1, wherein the housing is hermetically sealed.

19. The electromagnetic transducer according to claim 1, wherein the transducer is adapted to act as a sensor.

20. The electromagnetic transducer according to claim 19, wherein a vibration in the housing causes vibration in the magnets so as to cause a current in the at least one coil.

21. The electro-magnetic transducer according to claim 1, wherein the transducer is adapted to act as an actuator.

22. The electro-magnetic transducer according to claim 21, wherein alternating current flowing through the at least one coil causes vibration of the magnets, the vibration transferred to the housing.

23. An electromagnetic transducer comprising:

a housing;

at least one coil associated with the housing; and

a plurality of magnets within the housing, the magnets aligned along an axis in an anti-parallel orientation, the magnets mechanically free to move along the axis, wherein current flowing through the at least one coil causes movement of the magnet along the axis which in turn causes movement of a driver shaft.

24. The electromagnetic transducer according to claim 23, further comprising at least one biasing member positioned between one of the magnets and the housing, the biasing member for biasing movement of the magnets.

25. The electromagnetic transducer according to claim 23, wherein movement of the driver shaft causes the magnet to move such that current flows through the at least one coil.

26. An electromagnetic transducer comprising:

a housing having an axis;

at least one coil associated with the housing; and

a quadrupolar magnet with the housing, the magnet free to move along an axis, wherein vibration of the magnet causes vibration of the housing.

27. The electromagnetic transducer according to claim 26, further comprising at least one biasing member positioned between the magnet and the housing, the biasing member for biasing movement of the magnet.

28. The electromagnetic transducer according to claim 26, wherein the transducer is substantially free of torque in the presence of an external magnetic field.

29. An electro-magnetic transducer comprising:

a housing;

at least one coil associated with the housing;

a spherical magnet within the housing, the magnet capable of turning in any direction and of moving along an axis; and

a first keeper that includes magnetically soft material and that is free to move along the axis, the first keeper attracted by a magnetic pole of the magnet in the absence of an external magnetic field, such that opposing magnetic poles of the magnet are aligned parallel to the axis, wherein alternating current flowing through the at least one coil causes a vibration of the magnet, the vibration transferred to the housing.

30. The electromagnetic transducer according to claim 29, further comprising a non-magnetic adapter which is free to move along the axis and which holds the first keeper centered on the axis.

31. The electromagnetic transducer according to claim 29, further comprising a second keeper that includes magnetically soft material, the first and second keeper positioned on opposite sides of the magnet.

32. The electromagnetic transducer of claim 31, further comprising:

a first non-magnetic adapter which is free to move along the axis and which holds the first keeper centered on the axis;

and a second non-magnetic adapter which is free to move along the axis and which holds the second keeper centered on the axis, the first keeper and second keeper positioned on opposite sides of the magnet.

33. The electromagnetic transducer according to claim 29, further comprising at least one biasing member positioned between the magnet and the housing, the biasing member for biasing movement of the magnet.

34. The electromagnetic transducer according to claim 33, wherein the at least one biasing member is flexible and resilient.

35. The electro-magnetic transducer according to claim 33, wherein the at least one biasing member includes one of a spring and a silicone material.

36. The electromagnetic transducer according to claim 33, wherein the at least one biasing member prevent the magnets from directly contacting the housing.

37. The electromagnetic transducer according to claim 29, wherein the transducer is substantially free of torque in the presence of an external magnetic field.

38. The electromagnetic transducer according to claim 37, wherein the external magnetic field is caused by a Magnetic Resonance Imaging device.

39. The electromagnetic transducer according to claim 29, wherein the housing is adapted to be fixed to an ossicle.

40. The electromagnetic transducer according to claim 29, wherein the at least one coil is positioned within the housing.

41. The electromagnetic transducer according to claim 29, wherein the at least one coil is positioned external to the housing.

42. The electromagnetic transducer according to claim 29, wherein at least one of the magnets and an inner wall of the housing are coated with a material having a low coefficient of friction.

43. The electro-magnetic transducer according to claim 42, wherein the material is Teflon.

44. The electromagnetic transducer according to claim 29, wherein the friction of the magnet is reduced by a lubricant.

45. The electromagnetic transducer according to claim 29, wherein the at least one coil includes a plurality of coils, and wherein the induced voltage of the plurality of coils arising from an external RF field is zero.

46. The electromagnetic transducer according to claim 45, wherein the at least one coil includes a first and second outer coil, and a middle coil positioned between the first and second outer coils, wherein the middle coil is winded in a direction opposite the two outer coils, and wherein the number of loops of the middle coil equals the sum of loops of the first and second outer coils.

47. The electro-magnetic transducer according to claim 29, wherein the housing is hermetically sealed.

48. The electromagnetic transducer according to claim 29, wherein the transducer is adapted to act as a sensor.

49. The electro-magnetic transducer according to claim 48, wherein a vibration in the housing causes vibration in the magnets so as to cause a current in the at least one coil.

50. The electromagnetic transducer according to claim 29, wherein the transducer is adapted to act as an actuator.

81. The electromagnetic transducer according to claim 29, wherein an orientation of the magnetic moment of the spherical magnet can be defined by applying an axial magnetic field of a predefined orientation.

82. The electromagnetic transducer of claim 81, wherein the axial magnetic field is capable of causing a phase shift of 0°

or 180°

between current flow in the at least one coil(s) and motion of the spherical magnet.

51. An electromagnetic driver transducer comprising:

a housing;

at least one coil associated with the housing;

a spherical magnet within the housing, the magnet capable of turning in any direction and of moving along an axis; and

a keeper that includes magnetically soft material and that is free to move along the axis, the keeper attracted by a magnetic pole of the magnet in the absence of an external magnetic field, such that opposing magnetic poles of the magnet are aligned parallel to the axis, wherein current flowing through the at least one coil can cause movement of the magnet which in turn moves a driver shaft.

52. The electromagnetic transducer according to claim 51, further comprising at least one biasing member positioned between the magnet and the driver shaft, the biasing member for biasing movement of the magnet.

53. The electromagnetic transducer according to claim 51, wherein movement of the driver shaft causes the magnet to move such that current flows through the at least one coil.

54. An electromagnetic transducer comprising:

a housing;

at least one coil; and

a plurality of spherical magnets within the housing, the magnets capable of turning in any direction and of movement along an axis, wherein vibration of the magnets causes vibration of the housing.

55. The electromagnetic transducer according to claim 54, wherein the plurality of spherical magnets include a first and second magnet.

56. The electromagnetic transducer according to claim 54, further comprising a non-magnetic adapter placed between each of the magnets, each adapter free to move along the axis.

57. The electromagnetic transducer according to claim 56, wherein the non-magnetic adapter is one of a ball bearing and a slide bearing.

58. The electromagnetic transducer according to claim 54, further comprising at least one biasing member positioned between the magnets and the housing, the biasing member for biasing movement of the magnets.

59. The electromagnetic transducer according to claim 58, wherein the at least one biasing member is flexible and resilient.

60. The electromagnetic transducer according to claim 58, wherein the at least one biasing member includes one of a spring and a silicone material.

61. The electromagnetic transducer according to claim 58, wherein the at least one biasing member prevent the magnets from directly contacting the housing.

62. The electromagnetic transducer according to claim 54, wherein the at least one coil includes a plurality of coils, wherein the induced voltage of the plurality of coils arising from an external RF field is zero.

63. The electro-magnetic transducer according to claim 62, wherein the at least one coil includes a first and second coil, the first coil wound in a direction opposite the second coil.

64. The electromagnetic transducer according to claim 54, wherein the at least one coil is positioned within the housing.

65. The electromagnetic transducer according to claim 54, wherein the at least one coil is positioned external to the housing.

66. The electromagnetic transducer according to claim 54, further comprising a switching element as a function of an orientation of an external magnetic field.

67. The electromagnetic transducer according to claim 54, wherein the transducer is substantially free of torque in the presence of an external magnetic field.

68. The electromagnetic transducer according to claim 67, wherein the external magnetic field is caused by a Magnetic Resonance Imaging device.

69. The electromagnetic transducer according to claim 54, wherein the housing is adapted to be fixed to an ossicle.

70. The electromagnetic transducer according to claim 54, wherein at least one of the magnets and an inner wall of the housing are coated with a material having a low coefficient of friction.

71. The electromagnetic transducer according to claim 70, wherein the material is Teflon.

72. The electro-magnetic transducer according to claim 54, wherein the housing is hermetically sealed.

73. The electromagnetic transducer according to claim 54, wherein the transducer is adapted to act as a sensor.

74. The electromagnetic transducer according to claim 73, wherein a vibration in the housing causes vibration in the magnets so as to cause a current in the at least one coil.

75. The electromagnetic transducer according to claim 54, wherein the transducer is adapted to act as an actuator.

76. The electromagnetic transducer according to claim 75, wherein alternating current flowing through the at least one coil causes vibration of the magnets, the vibration transferred to the housing.

83. The electromagnetic transducer according to claim 54, wherein an orientation of the magnetic moment of the spherical magnets can be defined by applying an axial magnetic field of a predefined orientation.

84. The electromagnetic transducer of claim 83, wherein the axial magnetic field is capable of causing a phase shift of 0°

or 180°

between current flow in the at least one coil(s) and motion of the spherical magnets.

77. An electromagnetic transducer comprising:

a housing;

at least one coil; and

a plurality of spherical magnets within the housing, the magnets capable of turning in any direction and of movement along an axis, wherein current flowing through the at least one coil causes movement of the magnet along the axis which in turn causes movement of a driver shaft.

78. The electromagnetic transducer according to claim 77, wherein movement of the driver shaft causes the magnet to move such that current flows through the at least one coil.

79. A rotational mass transducer comprising:

a housing;

a coil mounted to the housing;

a spherical magnet within the housing, the magnet free to turn into any direction; and

at least one keeper that includes magnetically soft material and that is fixed to the housing such that the magnet, in the absence of an external magnetic field, is oriented so that the magnetic moment of the spherical magnet is perpendicular to a magnetic field generated by current flowing through the coil, wherein an alternating current flow through the coil causes an alternating torque to be exerted on the magnet, which in turn causes a rotational vibration of the housing.

80. The rotational mass transducer according to claim 79, wherein the housing is adapted to be fixed to an ossicle.

85. A method of improving hearing in a subject, the method comprising:

surgically implanting a transducer in the subject, the transducer including a housing, at least one coil associated with the housing; and

a plurality of magnets within the housing, the magnets aligned along an axis in an anti-parallel orientation, the magnets free to move along the axis; and

causing current to flow through the at least one coil so as vibrate the magnets and cause vibration of the housing.

86. The method according to claim 85, wherein said implanting includes securing said housing to an ossicle in the middle ear.

87. A method of sensing vibration in a subject, the method comprising:

surgically implanting a transducer in the subject, the transducer including a housing, at least one coil associated with the housing, and a plurality of magnets within the housing, the magnets aligned along an axis in an anti-parallel orientation, the magnets free to move along the axis; and

sensing current generated in the coil caused by vibration of the magnets.

88. The method according to claim 87, wherein said implanting included securing said housing to an ossicle in the middle ear.

89. A method of driving a shaft, the method comprising:

providing a transducer that includes a housing, at least one coil associated with the housing, and a plurality of magnets within the housing, the magnets aligned along an axis in an anti-parallel orientation, the magnets mechanically free to move along the axis; and

causing a current to flow through the at least one coil so as to move the magnet along the axis, wherein movement of the magnet causes the drive shaft to move.

90. A method of improving hearing in a subject, the method comprising:

surgically implanting a transducer in the subject, the transducer including;

a housing,

at least one coil associated with the housing,

a spherical magnet within the housing, the magnet capable of turning in any direction and of moving along an axis, and

a first keeper that includes magnetically soft material and that is free to move along the axis, the first keeper attracted by a magnetic pole of the magnet in the absence of an external magnetic field, such that opposing magnetic poles of the magnet are aligned parallel to the axis

causing current to flow through the at least one coil so as to cause a vibration of the magnet, the vibration transferred to the housing.

91. The method according to claim 90, wherein said implanting includes securing said housing to an ossicle in the middle ear.

92. A method of sensing vibration in a subject, the method comprising:

surgically implanting a transducer in the subject, the transducer including;

a housing,

at least one coil associated with the housing,

a spherical magnet within the housing, the magnet capable of turning in any direction and of moving along an axis, and

a first keeper that includes magnetically soft material and that is free to move along the axis, the first keeper attracted by a magnetic pole of the magnet in the absence of an external magnetic field, such that opposing magnetic poles of the magnet are aligned parallel to the axis; and

sensing current generated in the coil caused by vibration of the magnets.

93. The method according to claim 92, wherein said implanting includes securing said housing to an ossicle in the middle ear.

94. A method of driving a shaft, the method comprising:

providing a transducer, the transducer including;

a housing,

at least one coil associated with the housing,

a spherical magnet within the housing, the magnet capable of turning in any direction and of moving along an axis, and

a first keeper that includes magnetically soft material and that is free to move along the axis, the first keeper attracted by a magnetic pole of the magnet in the absence of an external magnetic field, such that opposing magnetic poles of the magnet are aligned parallel to the axis; and

causing current to flow through the at least one coil so as to move the magnet along the axis, wherein movement of the magnet causes the drive shaft to move.

95. A method of improving hearing in a subject, the method comprising:

surgically implanting a transducer in the subject, the transducer including;

a housing;

at least one coil; and

a plurality of spherical magnets within the housing, the magnets capable of turning in any direction and of movement along an axis; and

causing current to flow through the at least one coil so as to cause a vibration of the magnets, the vibration transferred to the housing,

96. The method according to claim 95, wherein said implanting includes securing said housing to an ossicle in the middle ear.

97. A method of sensing vibration in a subject, the method comprising:

surgically implanting a transducer in the subject, the transducer including;

a housing;

at least one coil; and

a plurality of spherical magnets within the housing, the magnets capable of turning in any direction and of movement along an axis; and

sensing current generated in the coil caused by vibration of the magnets.

98. The method according to claim 97, wherein said implanting includes securing said housing to an ossicle in the middle ear.