Management of actuator dynamics in a multiple actuator hard disk drive with an unequal number of heads on the two outer arms of each actuator
A hard disk drive includes multiple actuator assemblies, each of which includes a head-stack assembly (HSA) including an end-arm to which a single head-gimbal assembly (HGA) is coupled, where this end-arm is configured with a notch along one side and a triangular or quadrilateral-shaped through-hole at a root-side of the end-arm, and where the HSA further includes a plurality of other end- and inner-arms to each of which two HGAs are coupled and none of which have a through-hole near their root. The single-HGA end-arm may be further configured with an outer damper having a through-hole coincident with the end-arm through-hole, such that the through-hole of the end-arm is not covered by this damper, and an inner damper having no through-hole, such that the through-hole of the end-arm is covered by this damper. Gains are thereby better matched across all HGAs for problematic arm and system modes.
1. A hard disk drive (HDD) head-stack assembly (HSA) comprising:
a first end-arm to which a single head-gimbal assembly (HGA) is coupled, the first end-arm comprising:
a notch along one side of the first end-arm;
a second end-arm to which two HGAs are coupled; and
a plurality of inner-arms positioned between the first and second end-arms and to each of which two HGAs are coupled;
wherein none of the plurality of inner-arms and the second end-arm comprise a notch configured equivalently to the notch of the first end-arm.
2. The HSA of claim 1 , wherein:
the first end-arm further comprises a swage pad at an end opposing a root of the first end-arm; and
the notch is a single notch spanning a portion of the one side of the first end-arm between the root and the swage pad.
3. The HSA of claim 1 , wherein the first end-arm further comprises:
a substantially triangular-shaped or substantially quadrilateral-shaped through-hole at a root-side of the first end-arm.
4. The HSA of claim 3 , wherein the through-hole is substantially quadrilateral-shaped having a first width at a first side nearer the root greater than a second width at a second side farther from the root.
5. The HSA of claim 3 , wherein none of the plurality of inner-arms and the second end-arm comprise a through-hole at a root-side of the inner-arm and a root-side of the second end-arm.
6. The HSA of claim 5 , further comprising:
a shared pivot shaft onto which the first and second end-arms are mounted in a hard disk drive.
7. The HSA of claim 3 , further comprising:
a top damper coupled to a top surface of the first end-arm and comprising a through-hole coincident with the through-hole of the first end-arm such that the through-hole of the first end-arm is not covered by the top damper.
8. The HSA of claim 7 , further comprising:
a bottom damper coupled to a bottom surface of the first end-arm and comprising no through-hole coincident with the through-hole of the first end-arm such that the through-hole of the first end-arm is covered by the bottom damper.
9. The HSA of claim 8 , further comprising:
a shared pivot shaft onto which the first and second end-arms are mounted in a hard disk drive.
10. The HSA of claim 7 , wherein the through-hole of the top damper is shaped the same as the through-hole of the first end-arm.
11. The HSA of claim 3 , wherein each of the plurality of inner-arms and the second end-arm comprises a through-hole at a root-side of the inner-arm and a root-side of the second end-arm, coincident with and smaller in area than the through-hole of the first end-arm.
12. The HSA of claim 1 , wherein:
each of the plurality of inner-arms and the second end-arm comprises a through-hole at a root-side of the inner-arm and a root-side of the second end-arm; and
the first end-arm comprises no through-hole at a root-side of the first end-arm.
13. The HSA of claim 1 , wherein:
the first end-arm further comprises a through-hole at a root-side of the first end-arm; and
each of the plurality of inner-arms and the second end-arm comprises a through-hole at a root-side of the inner-arm and a root-side of the second end-arm, coincident with and shaped the same as the through-hole of the first end-arm.
14. The HSA of claim 1 , further comprising:
a shared pivot shaft onto which the first and second end-arms are mounted in a hard disk drive.
15. A data storage device comprising:
a plurality of disk media rotatably mounted on a spindle;
a first actuator assembly comprising:
a first head-stack assembly (HSA) comprising:
an end-arm to which a single head-gimbal assembly (HGA) is coupled, the end-arm comprising:
a substantially triangular-shaped or substantially quadrilateral-shaped through-hole at a root-side of the end-arm;
a plurality of dual-HGA arms to each of which two HGAs are coupled, wherein none of the plurality of dual-HGA arms comprise a through-hole at a root-side of dual-HGA arm; and
a first head slider comprising a read-write head configured to write to and to read from one of the plurality of disk media; and
a second actuator assembly comprising:
a second head-stack assembly (HSA) comprising:
an end-arm to which a single head-gimbal assembly (HGA) is coupled, the end-arm comprising:
a substantially triangular-shaped or substantially quadrilateral-shaped through-hole at a root-side of the end-arm;
a plurality of dual-HGA arms to each of which two HGAs are coupled, wherein none of the plurality of dual-HGA arms comprise a through-hole at a root-side of dual-HGA arm; and
a second head slider comprising a read-write head configured to write to and to read from another of the plurality of disk media.
16. The data storage device of claim 15 , wherein:
the end-arm of the first HSA further comprises a notch along one side; and
the end-arm of the second HSA further comprises a notch along one side.
17. The data storage device of claim 16 , wherein none of the plurality of dual-HGA arms comprise a notch configured equivalently to the notch of the end-arm of the first and second HSAs.
18. The data storage device of claim 15 , further comprising:
a top damper coupled to a top non-disk-facing surface of each end-arm and comprising a through-hole coincident with the through-hole of the corresponding end-arm such that the through-hole of the end-arm is not covered by the top damper; and
a bottom damper coupled to a bottom disk-facing surface of each end-arm and comprising no through-hole coincident with the through-hole of the corresponding end-arm such that the through-hole of the end-arm is covered by the bottom damper.
19. The data storage device of claim 15 , wherein the through-hole of each end-arm is substantially quadrilateral-shaped having a first width at a first side nearer the root greater than a second width at a second side farther from the root.
20. A multi-actuator hard disk drive including an odd number of recording media including a shared center disk shared by multiple actuators, the system comprising:
a first actuator assembly comprising:
a first head-stack assembly (HSA) comprising:
a first single-HGA end-arm to which a single head-gimbal assembly (HGA) is coupled;
a first dual-HGA end-arm to which two HGAs are coupled and which is configured to service the shared center disk;
a plurality of first inner-arms to each of which two HGAs are coupled; and
means for reducing gain differences in the arm structural dynamics modes between the first single-HGA end-arm, and the first dual-HGA end-arm and the first inner-arms; and
a second actuator assembly comprising:
a second head-stack assembly (HSA) comprising:
a second single-HGA end-arm to which a single head-gimbal assembly (HGA) is coupled;
a second dual-HGA end-arm to which two HGAs are coupled and which is configured to service the shared center disk;
a plurality of second inner-arms to each of which two HGAs are coupled; and
means for reducing gain differences in the arm structural dynamics modes between the second single-HGA end-arm, and the second dual-HGA end-arm and the second inner-arms.
21. A hard disk drive (HDD) head-stack assembly (HSA) comprising:
a first end-arm to which a single head-gimbal assembly (HGA) is coupled, the first end-arm comprising:
a swage pad at an end opposing a root of the first end-arm, and
a single notch along one side of the first end-arm and spanning a portion of the one side of the first end-arm between the root and the swage pad;
a second end-arm to which two HGAs are coupled; and
a plurality of inner-arms positioned between the first and second end-arms and to each of which two HGAs are coupled.
22. A hard disk drive (HDD) head-stack assembly (HSA) comprising:
a first end-arm to which a single head-gimbal assembly (HGA) is coupled, the first end-arm comprising:
a notch along one side of the first end-arm, and
a substantially triangular-shaped or substantially quadrilateral-shaped through-hole at a root-side of the first end-arm;
a second end-arm to which two HGAs are coupled; and
a plurality of inner-arms positioned between the first and second end-arms and to each of which two HGAs are coupled.
23. The HSA of claim 22 , further comprising:
a top damper coupled to a top surface of the first end-arm and comprising a through-hole coincident with the through-hole of the first end-arm such that the through-hole of the first end-arm is not covered by the top damper; and
a bottom damper coupled to a bottom surface of the first end-arm and comprising no through-hole coincident with the through-hole of the first end-arm such that the through-hole of the first end-arm is covered by the bottom damper.