Read/write head with dynamic flying height control by magnetostriction
View Patent ↗A read/write head for use in a data storage device to control the low dynamic flying height in order to achieve high data recording storage capacity of magnetic hard drives. The read/write head is designed for use in a data storage device that includes a storage medium having a recording surface. The head comprises a pole tip region and an actuator. In turn, the actuator includes an excitation source for generating a magnetic field, and a magnetostrictive plate for expanding in response to the magnetic field, resulting in a protrusion in a section of the pole tip region along a direction towards the recording surface, so that the head flies above the recording surface at a flying height lower than a nominal flying height.
1. A head for use in a data storage device including a storage medium having a recording surface, the head comprising:
a pole tip region;
an actuator including:
an excitation source for generating a magnetic field; and
a magnetostrictive plate for expanding in response to the magnetic field, resulting in a protrusion in a section of the pole tip region along a direction towards the recording surface; and
a stop layer that is disposed behind the actuator, adjacent the magnetostrictive plate along the direction but opposite the protrusion.
2. The head of claim 1 , wherein the excitation source comprises a coil.
3. The head of claim 2 , wherein the magnetostrictive plate is placed in proximity to the coil, in order to saturate the coil when the coil is energized.
4. The head of claim 3 , wherein the magnetostrictive plate is made of a material that is selected from the group consisting of one or a combination of: cobalt; nickel; iron; rare earth material; oxides of cobalt, nickel, iron, or rare earth materials; additives of oxygen, nitrogen, fluoride, or boron to cobalt, nickel, iron, or rare earth materials.
5. The head of claim 1 , wherein the head comprises a first pole, P 1 , and wherein the actuator is disposed, at least in part, behind the first pole, P 1 .
6. The head of claim 1 , wherein the head comprises a first pole, P 1 , and a second pole, P 2 , and wherein the actuator is disposed, at least in part, behind the second pole, P 2 .
7. The head of claim 1 , wherein the head comprises a first pole, P 1 , a second pole, P 2 , and a third pole, P 3 , and wherein the actuator is disposed, at least in part, behind the third pole, P 3 .
8. The head of claim 1 , wherein the head comprises a write gap disposed within the pole tip region, and wherein the actuator is disposed, at least in part, behind the write gap.
9. The head of claim 1 , wherein the head comprises a read gap disposed within the pole tip region, and wherein the actuator is disposed, at least in part, behind the read gap.
10. The head of claim 1 , wherein the head comprises a first shield, S 1 , and wherein the actuator is disposed, at least in part, behind the first shield, S 1 .
11. The head of claim 1 , wherein the head comprises a first shield, S 1 and a second shield, S 2 , and wherein the actuator is disposed, at least in part, behind the second shield, S 2 .
12. The head of claim 1 , wherein the head comprises a first pole, P 1 ; a second pole, P 2 ; a third pole, P 3 ; a write gap disposed within the pole tip region; a read gap disposed within the pole tip region; a first shield, S 1 ; a second shield, S 2 ; a write coil; and
wherein the actuator is disposed, at least in part, behind any one or more of: the first pole, P 1 ; the second pole, P 2 ; the third pole, P 3 ; the write gap; the read gap; the first shield, S 1 ; the second shield, S 2 ; and the write coil.
13. The head of claim 12 , further comprising a third shield layer, S 3 , and a fourth shield layer, S 4 ; and wherein the actuator is disposed at least in part, behind the fourth shield layer, S 4 .
14. The head of claim 1 , further comprising an overcoat layer and wherein the actuator is disposed at least in part, behind the overcoat layer.
15. The head of claim 1 , wherein the stop layer comprises a non-magnetic material.
16. The head of claim 1 , wherein the expansion of the magnetostrictive plate is on the order of approximately 5 nm.
17. The head of claim 16 , wherein a magnetostriction of the magnetostrictive plate is on the order of approximately 5×10 −5 .
18. The head of claim 1 , wherein the magnetostrictive plate has a generally rectangular shape.
19. The head of claim 1 , wherein the magnetostrictive plate has a generally square shape.
20. The head of claim 1 , wherein the magnetostrictive plate has a generally trapezoidal shape.
21. The head of claim 1 , wherein the magnetostrictive plate has a generally elliptical shape.
22. The head of claim 1 , wherein the excitation source begins to be energized upon initiation of a data read operation.
23. The head of claim 1 , wherein the excitation source begins to be energized upon initiation of a data write operation.
24. The head of claim 1 , wherein when the head is idle, the actuator is not energized.
25. The head of claim 1 , wherein the head is a perpendicular recording head.
26. The head of claim 1 , wherein the head is a longitudinal recording head.
27. The head of claim 1 , wherein the excitation source is continuously energized during operation of the head, to compensate for flying height tolerance.
28. The head of claim 1 , wherein the excitation source is selectively energized only during a read operation.
29. The head of claim 1 , wherein the excitation source is selectively energized only during a write operation.
30. A disk drive comprising:
a base;
a spindle motor attached to the base;
a disk having a recording surface and positioned on the spindle motor;
a head stack assembly coupled to the base and comprising:
an actuator body;
an actuator arm cantilevered from the actuator body; and
a read/write head coupled to the actuator arm, and including:
a pole tip region; and
an actuator including:
an excitation source for generating a magnetic field; and
a magnetostrictive plate for expanding in response to the magnetic field, resulting in a protrusion in a section of the pole tip region along a direction towards the recording surface; and
a stop layer that is disposed behind the actuator, adjacent the magnetostrictive plate along the direction but opposite the protrusion.
31. The disk drive of claim 30 , wherein the excitation source comprises a coil.
32. The disk drive of claim 31 , wherein the magnetostrictive plate is placed in proximity to the coil, in order to saturate the coil when the coil is energized.
33. The disk drive of claim 32 , wherein the magnetostrictive plate is made of a material that is selected from the group consisting of one or a combination of: cobalt; nickel; iron; rare earth material; oxides of cobalt, nickel, iron, or rare earth materials; additives of oxygen, nitrogen, fluoride, or boron to cobalt, nickel, iron, or rare earth materials.
34. The disk drive of claim 30 , wherein the head comprises a first pole, P 1 , and wherein the actuator is disposed, at least in part, behind the first pole, P 1 .
35. The disk drive of claim 30 , wherein the head comprises a first pole, P 1 , and a second pole, P 2 , and wherein the actuator is disposed, at least in part, behind the second pole, P 2 .
36. The disk drive of claim 30 , wherein the head comprises a first pole, P 1 , a second pole, P 2 , and a third pole, P 3 , and wherein the actuator is disposed, at least in part, behind the third pole, P 3 .
37. The disk drive of claim 30 , wherein the head comprises a write gap disposed within the pole tip region, and wherein the actuator is disposed, at least in part, behind the write gap.
38. The disk drive of claim 30 , wherein the head comprises a read gap disposed within the pole tip region, and wherein the actuator is disposed, at least in part, behind the read gap.
39. The disk drive of claim 30 , wherein the head comprises a first shield, S 1 , and wherein the actuator is disposed, at least in part, behind the first shield, S 1 .
40. The disk drive of claim 30 , wherein the head comprises a first shield, S 1 and a second shield, S 2 , and wherein the actuator is disposed, at least in part, behind the second shield, S 2 .
41. The disk drive of claim 30 , wherein the stop layer comprises a non-magnetic material.
42. The disk drive of claim 40 , wherein the expansion of the magnetostrictive plate is on the order of approximately 5 nm.
43. The disk drive of claim 42 , wherein a magnetostriction of the magnetostrictive plate is on the order of approximately 5×10 −5 .
44. The disk drive of claim 30 , wherein the magnetostrictive plate has a generally rectangular shape.
45. The disk drive of claim 30 , wherein the magnetostrictive plate has a generally square shape.
46. The disk drive of claim 30 , wherein the magnetostrictive plate has any of a generally trapezoidal shape or a generally elliptical shape.
47. The disk drive of claim 30 , wherein the excitation source begins to be energized upon initiation of a data read operation.
48. The disk drive of claim 30 , wherein the excitation source begins to be energized upon initiation of a data write operation.
49. The disk drive of claim 30 , wherein when the head is idle, the actuator is not energized.
50. The disk drive of claim 30 , wherein the head comprises a first pole, P 1 ; a second pole, P 2 ; a third pole, P 3 ; a write gap disposed within the pole tip region; a read gap disposed within the pole tip region; a first shield, S 1 ; a second shield, S 2 ; a write coil; and
wherein the actuator is disposed, at least in part, behind any one or more of: the first pole, P 1 ; the second pole, P 2 ; the third pole, P 3 ; the write gap; the read gap; the first shield, S 1 ; the second shield, S 2 ; and the write coil.
51. The disk drive of claim 50 , further comprising a third shield layer, S 3 , and a fourth shield layer, S 4 ; and wherein the actuator is disposed at least in part, behind the fourth shield layer, S 4 .
52. The disk drive of claim 30 , further comprising an overcoat layer and wherein the actuator is disposed at least in part, behind the overcoat layer.
53. The disk drive of claim 30 , wherein the head is a perpendicular recording head.
54. The disk drive of claim 30 , wherein the head is a longitudinal recording head.
55. The disk drive of claim 30 , wherein the excitation source is continuously energized during operation of the head, to compensate for flying height tolerance.
56. The disk drive of claim 30 , wherein the excitation source is selectively energized only during a read operation.
57. The disk drive of claim 30 , wherein the excitation source is selectively energized only during a write operation.