Split VCM actuator

• US 6,847,504 B1
• Filed: 04/30/2002
• Issued: 01/25/2005
• Est. Priority Date: 04/30/2002
• Status: Expired due to Term

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Bennett, George J., Patton, Charles R. III
• Primary Examiner(s): Tran, Sinh
• Assistant Examiner(s): Tzeng, Fred
• Application Number:
  US10/137,227
• Time in Patent Office: 1,001 Days
• Field of Search: 360/78.12, 360/78.04, 360/75, 360/77.02, 360/77.06, 360/97.01, 360/97.02, 360/25, 360/31, 360/245.2, 360/245.7, 360/264.4, 360/264.5, 360/264.7
• US Class Current: 360/78.12
• CPC Class Codes: G11B 5/4813 Mounting or aligning of arm assemblies, e.g. actuator arm supported by bearings, multiple arm assemblies, arm stacks or multiple heads on single arm G11B5/484 takes precedence
• CPC Class Codes: G11B 5/4833 Structure of the arm assembly, e.g. load beams, flexures, parts of the arm adapted for controlling vertical force on the head G11B5/484 takes precedence

Abstract

A split actuator comprising two spring coupled actuators that share a common pivot bearing. The two reduced inertia actuators permit overlapping motions during a seek operation thereby reducing dead times in transfer of data between disk and transducers disposed on the actuators. A spring member that spring couples the two actuators boosts relative motions by storing and releasing spring potential energy selectively. The spring member is also configured so as to substantially restrict the relative motions of the two actuators to rotational motions about a common axis of the common pivot bearing. Rigidity of the spring member to non-rotational relative motions, as well as tuning of the spring member to provide a rigid response to selected frequencies, the spring member in conjunction with the common pivot bearing result in mechanical disturbance being substantially common to the two actuators, thereby allowing predictable and manageable disturbance corrections.

Claims

1. A disk drive comprising:

a rotatable disk having a magnetic recording media formed on a surface of the rotatable disk wherein the rotatable disk defines a plurality of concentric data tracks;

a pivot point positioned adjacent the rotatable disk wherein the pivot point defines an axis;

a rotatable pivot assembly positioned on the pivot point so as to rotate about the axis defined by the pivot point;

a first actuator having a first transducer coupled to the pivot assembly so as to be rotatable about the axis wherein the first actuator extends over the surface of the rotatable disk such that rotation of the pivot assembly results in movement of the first transducer over the surface of the rotatable disk such that the first transducer can be positioned adjacent selected data tracks;

a first coil that is disposed with respect to the first actuator so as to induce movement of the first actuator and the first transducer with respect to the surface of the disk;

a second actuator having a second transducer coupled to the pivot assembly so as to be rotatable about the axis wherein the second actuator extends over the surface of the rotatable disk such that rotation of the pivot assembly results in movement of the second transducer over the surface of the rotatable disk such that the second transducer can be positioned adjacent selected data tracks;

a second coil that is disposed with respect to the second actuator so as to induce movement of the second actuator and the second transducer with respect to the surface of the disk; and

a mechanical interconnect structure that couples the first and second actuators so as to permit limited relative movement of the first and second actuators such that when the pivot assembly is rotated to a first angular position with the first transducer in a first position adjacent a first selected data track and the second transducer is in a second position adjacent a second selected data track, the first transducer can be moved by the first coil to a third position adjacent a third selected data track without moving the second transducer from the second selected data track.

2. The disk drive of claim 1, wherein the second actuator is coupled to the pivot assembly by the mechanical interconnect structure thereby coupling the first and second actuators wherein the first and second actuators are influenced by a common vibration associated with the pivot assembly.

3. The disk drive of claim 2, wherein the disk drive comprises one or more disks wherein each disk defines a top surface and a bottom surface.

4. The disk drive of claim 3, wherein each of the first and second actuators comprises at least one arm wherein at least one transducer is disposed on each of the at least one arm and wherein the at least one arm of the first actuator is arranged with respect to the at least one arm of the second actuator in an alternating manner such that the alternating arms are arranged in an interleaving manner with respect to the one or more disks.

5. The disk drive of claim 4, wherein the disk drive comprises two disks.

6. The disk drive of claim 5, wherein the first actuator comprises two arms and wherein the second actuator comprises one arm interposed between the two arms of the first actuator.

7. The disk of claim 4, wherein the disk drive comprises three disks.

8. The disk of claim 7, wherein the first actuator comprises two arms and wherein the second actuator comprises two arms that alternate with the two arms of the first actuator.

9. The disk drive of claim 2, wherein the pivot assembly comprises a cylindrical member having a cylindrical axis that is substantially co-axial with the axis defined by the pivot point wherein the cylindrical member is adapted to allow mounting of the first and second actuators such that the first and second actuators are mechanically coupled.

10. The disk drive of claim 1, wherein the mechanical interconnect structure is a spring member that spring couples the first and second actuators.

11. The disk drive of claim 10, wherein the spring member comprises a plurality of flex sections wherein each flex section is a vertically oriented panel with a first edge attached to a portion of the first actuator and a second edge attached to a portion of the second actuator wherein the first and second edges are two opposing edges.

12. The disk drive of claim 11, wherein the flex sections allow relative motion of the first and second actuators in a first mode while resisting other modes of the relative motion.

13. The disk drive of claim 12, wherein the first and second edges of the flex section are inner and outer edges that attach to the first and second actuators respectively.

14. The disk drive of claim 13, wherein the spring member comprises four flex sections distributed substantially evenly circumferentially so as to provide symmetry about the axis defined by the pivot wherein the symmetry of the arrangement of the flex sections inhibits non-rotational relative motion between the first and second actuators.

15. The disk drive of claim 11, wherein the flex sections allow a limited spring-coupled rotational relative motion between the first and second actuators.

16. The disk drive of claim 10, wherein the spring member acquires and stores potential energy as the first and second actuators undergo relative rotational displacement.

17. The disk drive of claim 16, wherein the spring member releases the stored potential energy at a selected instance so as to facilitate subsequent rotational relative motion of the first and second actuators.

18. The disk drive of claim 17, wherein each of the first and second actuators has a reduced inertia thereby allowing greater acceleration for a given applied power.

19. The disk drive of claim 18, wherein the spring member allows the first transducer to begin moving in a seek operation while the second transducer is performing a disk data transfer on a selected data track.

20. The disk drive of claim 19, wherein separate movements of the first and second actuators reduces a dead time during which disk data transfer is not being performed.

21. The disk drive of claim 20, wherein the dead time is substantially zero for seek operations involving seek lengths less than a selected distance.

22. The disk drive of claim 16, wherein controlling of the motion of the first and second actuators is performed so as to utilize the oscillatory property of the spring member thereby enhancing the controlling effect on the motion of the first and second actuators.

23. A disk drive comprising:

a rotatable disk having a magnetic recording media formed on a surface of the rotatable disk wherein the rotatable disk defines a plurality of concentric data tracks;

a first actuator having a first transducer and a first coil mounted to a pivot assembly so as to be rotatable about an axis defined by the pivot assembly wherein the first coil induces movement of the first actuator;

a second actuator having a second transducer and a second coil mounted on the pivot assembly so as to be rotatable about the axis defined by the pivot assembly wherein the second coil induces movement of the second actuator; and

a spring member that interconnects and provides a spring coupling between the first and second actuators such that motion of one actuator affects the other actuator wherein the spring coupling allows the spring member to acquire spring potential energy during a first relative motion of the first and second actuators and release at least a selected portion of the acquired spring potential energy during a second relative motion thereby increasing the rate at which the second relative motion occurs and wherein the spring coupling involves a force that is mutual between the two actuators and generally isolated therebetween such that effects of the force on other parts of the disk drive is reduced.

24. The disk drive of claim 23, wherein the spring coupling provided by the spring member allows one of the two actuators to be controlled predictably in response to motion of the other actuator.

25. The disk drive of claim 24, wherein the first actuator moves while the second actuator remains over a selected data track wherein the second actuator is controlled to compensate for the spring member acquiring the spring potential energy thereby allowing the first transducer to initiate a seek operation while the second transducer is performing a disk data transfer.

26. The disk drive of claim 25, wherein mechanical disturbance experienced by one actuator is transferred to the other actuator predictably via the spring coupling thereby allowing the coupled mechanical disturbance to be compensated in both actuators in a simplified manner.

27. The disk drive of claim 23, wherein the spring member includes a structure that allows relative motion of the first and second actuators in a first mode while resisting other modes of the relative motion.

28. The disk drive of claim 27, wherein the spring member allows a limited range of rotational relative motion between the first and second actuators about the axis defined by the pivot assembly wherein the spring member also inhibits non-rotational relative motions between the first and second actuators.

29. The disk drive of claim 28, wherein the spring member comprises a plurality of flex sections wherein each flex section is a vertically oriented panel with a first edge attached to a portion of the first actuator and a second edge attached to a portion of the second actuator wherein the first and second edges are two opposing edges.

30. The disk drive of claim 29, wherein the first and second edges of the flex section are inner and outer edges that attach to the first and second actuators respectively.

31. The disk drive of claim 30, wherein the spring member comprises four flex springs distributed substantially evenly circumferentially so as to provide symmetry about the axis defined by the pivot wherein the symmetry of the arrangement of the flex springs inhibits non-rotational relative motion between the inner and outer portions.

32. The disk drive of claim 23, wherein the spring member acquires and stores potential energy as the first and second actuators undergo relative rotational displacement.

33. The disk drive of claim 32, wherein the spring member releases the stored potential energy at a selected instance so as to facilitate subsequent rotational relative motion of the first and second actuators.

34. The disk drive of claim 33, wherein each of the first and second actuators has a reduced inertia thereby allowing greater acceleration for a given applied power.

35. The disk drive of claim 34, wherein the spring member allows the first transducer to begin moving in a seek operation while the second transducer is performing a disk data transfer on a selected data track.

36. The disk drive of claim 32, wherein separate movements of the first and second actuators reduces a dead time during which disk data transfer is not being performed.

37. The disk drive of claim 36, wherein the dead time is substantially zero for seek operations involving seek lengths less than a selected distance.

38. The disk drive of claim 32, wherein controlling of the motion of the first and second actuators is performed so as to utilize the oscillatory property of the spring member thereby enhancing the controlling effect on the motion of the first and second actuators.

39. A method of performing a seek operation in a hard disk drive comprising a rotatable disk having a magnetic recording media, and an actuator assembly that includes a first transducer mounted on a first rotatable actuator and a second transducer mounted on a second rotatable actuator, the method comprising:

initiating movement of the first actuator at time T0 while maintaining the second transducer at a first location on the disk to perform a disk data transfer, wherein the resulting relative motion of the first and second actuators causes an interaction of the first and second actuators wherein the interaction causes some of kinetic energy of the relative motion to be stored as potential energy; and

terminating the disk data transfer of the second transducer at the first location at time T1 and initiating movement of the second actuator wherein at least a portion of the potential energy stored as a result of the interaction of the first and second actuators is converted into kinetic energy of the second actuator thereby increasing the rate of the second actuator'"'"'s movement.

40. The method of claim 39, wherein initiating movement of the first actuator comprises initially supplying the first actuator with a substantially full power available to both actuators so as to cause an increased acceleration of the first actuator.

41. The method of claim 40, wherein the increased acceleration of the first actuator reduces duration of first actuator'"'"'s movement.

42. The method of claim 39, wherein maintaining the second transducer at the first location while the first actuator is moving comprises supplying the second actuator with controlled power to compensate for interaction between the first and second actuators.

43. The method of claim 42, wherein the interaction between the first and second actuators is a spring-coupled interaction.

44. The method of claim 43, wherein initiating movement of the second actuator comprises releasing the second actuator by stopping the controlled power thereby allowing the spring-coupled second actuator to be accelerated along with the first actuator.

45. The method of claim 44, wherein the spring coupling reduces duration of the second actuator'"'"'s movement.

46. The method of claim 39, further comprising stopping the first actuator and performing a disk data transfer with the first transducer while the second actuator is still in motion.

47. The method of claim 46, wherein switching of the second transducer to the first transducer as the disk operating transducer reduces a dead time during which disk data transfer is not being performed.

48. The method of claim 47, wherein the dead time is substantially zero for seek operations involving seek lengths less than a selected distance.

49. The method of claim 46, wherein stopping the first actuator comprises supplying the first actuator with a substantially full power available to both actuators so as to cause an increased deceleration of the first actuator.

50. The method of claim 39, further comprising stopping the first actuator and utilizing the spring member to facilitate stopping of the second actuator wherein the second transducer performs a disk data transfer after the second actuator has stopped.

51. The method of claim 50, wherein stopping the second actuator comprises controlling the deceleration of the first and second actuators such that oscillatory motion between the two actuators due to the spring interaction enhances the effects of the controlled deceleration.