Abstract: 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.

Abstract: 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.

Abstract: Control circuitry is disclosed configured to control inner fine actuators of a first plurality of inner actuator arms and independently control a first outer fine actuator of a first outer actuator arm. Inner fine actuators of a second plurality of inner actuator arms are controlled while independently controlling a second outer fine actuator of a second outer actuator arm. Each actuator arm comprises at least one head configured to access a disk surface of a disk.

Abstract: Control circuitry is disclosed configured to control inner fine actuators of a first plurality of inner actuator arms and independently control a first outer fine actuator of a first outer actuator arm. Inner fine actuators of a second plurality of inner actuator arms are controlled while independently controlling a second outer fine actuator of a second outer actuator arm. Each actuator arm comprises at least one head configured to access a disk surface of a disk.

Abstract: 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.

Abstract: A multi-actuator data storage device such as a hard disk drive may include a lower actuator-pivot-VCM assembly including a lower pivot shaft and a lower motor assembly, an upper actuator-pivot-VCM assembly including an upper pivot shaft and an upper motor assembly, and a central support structure or plate sandwiched between the lower and upper pivot shafts and the lower and upper motor assemblies. The central support structure may be shaped to make contact with the motor assemblies only at discrete assembly locations and to make contact with the pivot shafts at opposing raised pads. Viscoelastic dampers may be adhered to the central support structure at the contact locations to dampen motor vibrational modes and/or to reduce the amplitude of vibration transmitted among the actuator-pivot assemblies. Such an assembly may increase the tilt and in-phase butterfly mode frequencies and decrease the gains of the tilt and coil torsion modes.

Abstract: An actuator pivot shaft assembly for a multi-actuator data storage device may include one or more annular grooves extending radially inward from an outer surface of the pivot shaft, thereby desirably weakening or structurally decoupling the shaft between the actuators, to assist with inhibiting transmission of vibration between the actuators during operation. The shaft assembly may further include an elastomeric damper positioned within the annular groove(s), to damp transmission of vibrational forces between the actuators through the shared shaft.

Abstract: A split-shaft pivot assembly for a dual-actuator data storage device may include a first pivot shaft around which a first bearing assembly is affixed, a second pivot shaft around which a second bearing assembly is affixed, and whereby the two pivot shafts are coupled together by way of an interface spacer between the shafts. The interface spacer may include a receiving structure at each end of a housing, for receiving an end of a respective shaft, and an annular slot circumscribing the housing between the receiving structures, where an elastomeric damper is positioned within the slot. The interface spacer housing may be composed of a material having a lower elastic modulus than the material of which the shafts are composed, thereby making the interface spacer relatively compliant. Such features may serve to inhibit and/or damp transmission of vibrational energy among the actuators through the shared split-shaft.

Abstract: An actuator pivot assembly for a multi-actuator shared shaft data storage device may include a shared pivot shaft around which a first rotary actuator assembly is coupled, with a first bearing assembly interposed therebetween with a first bearing preload, and around which a second rotary actuator assembly is coupled, with a second bearing assembly interposed therebetween with a second different bearing preload. Furthermore, the first bearing assembly may have a first bearing span and the second bearing assembly may have a second bearing span that is different from the first bearing span. Each of the foregoing bearing features may thereby assist with spacing apart the structural resonance frequencies of the actuator assemblies to inhibit transmission of vibration between the actuators during operation.

Abstract: A split-shaft pivot assembly for a dual-actuator data storage device may include a first pivot shaft having a threaded stud extending from one end and an attachment flange at the other end, and a second pivot shaft having a threaded bore at one end a structurally equivalent attachment flange at the other end, where the two pivot shafts are attached to each other by threading the stud into the bore. A first bearing assembly may be affixed with a first preload around the first pivot shaft, and a second bearing assembly may be affixed with a second different preload around the second pivot shaft. The pivot assembly may further include an elastomeric damper positioned within an annular groove formed in, and around the threaded stud of, the first pivot shaft. Such features may serve to inhibit and/or damp transmission of vibrational energy among the actuators through the shared split-shaft.

Abstract: A split-shaft pivot assembly for a dual-actuator data storage device may include a first pivot shaft around which a first bearing assembly is affixed, a second pivot shaft around which a second bearing assembly is affixed, and whereby the two pivot shafts are coupled together by way of an interface spacer between the shafts. The interface spacer may include a receiving structure at each end of a housing, for receiving an end of a respective shaft, and an annular slot circumscribing the housing between the receiving structures, where an elastomeric damper is positioned within the slot. The interface spacer housing may be composed of a material having a lower elastic modulus than the material of which the shafts are composed, thereby making the interface spacer relatively compliant. Such features may serve to inhibit and/or damp transmission of vibrational energy among the actuators through the shared split-shaft.

Abstract: A split-shaft pivot assembly for a dual-actuator data storage device may include a first pivot shaft having a threaded stud extending from one end and an attachment flange at the other end, and a second pivot shaft having a threaded bore at one end a structurally equivalent attachment flange at the other end, where the two pivot shafts are attached to each other by threading the stud into the bore. A first bearing assembly may be affixed with a first preload around the first pivot shaft, and a second bearing assembly may be affixed with a second different preload around the second pivot shaft. The pivot assembly may further include an elastomeric damper positioned within an annular groove formed in, and around the threaded stud of, the first pivot shaft. Such features may serve to inhibit and/or damp transmission of vibrational energy among the actuators through the shared split-shaft.

Abstract: An actuator pivot assembly for a multi-actuator shared shaft data storage device may include a shared pivot shaft around which a first rotary actuator assembly is coupled, with a first bearing assembly interposed therebetween with a first bearing preload, and around which a second rotary actuator assembly is coupled, with a second bearing assembly interposed therebetween with a second different bearing preload. Furthermore, the first bearing assembly may have a first bearing span and the second bearing assembly may have a second bearing span that is different from the first bearing span. Each of the foregoing bearing features may thereby assist with spacing apart the structural resonance frequencies of the actuator assemblies to inhibit transmission of vibration between the actuators during operation.

Abstract: A post-assembly head/disk offset adjuster is disclosed. One embodiment provides a housing and at least one disk coupled with the housing. In addition, an adjustable pivot plate is coupled with the housing such that access to at least one adjustment point of the adjustable pivot plate is provided regardless of a state of assembly of the hard disk drive. Furthermore, an actuator is coupled with the adjustable pivot plate. In so doing, an adjustment to the at least one adjustment point of the adjustable pivot plate results in an adjustment to the actuator regardless of the state of assembly of the hard disk drive.

Abstract: A post-assembly head/disk offset adjuster is disclosed. One embodiment provides a housing and at least one disk coupled with the housing. In addition, an adjustable pivot plate is coupled with the housing such that access to at least one adjustment point of the adjustable pivot plate is provided regardless of a state of assembly of the hard disk drive. Furthermore, an actuator is coupled with the adjustable pivot plate. In so doing, an adjustment to the at least one adjustment point of the adjustable pivot plate results in an adjustment to the actuator regardless of the state of assembly of the hard disk drive.

Abstract: A data recording disk drive has damping plates with nonplanar surfaces for reducing flow-induced, out-of-plane vibration of the disks. The nonplanar damping plates reduce spindle motor torque, as compared with planar damping plates, while reducing the turbulent intensity. Each damping plate has a nonplanar surface that results in spacing between the plate surface and its associated disk surface that varies in the radial direction. The nonplanar surface may be a pattern of surface irregularities or features that may be arranged in concentric patterns, such as a pattern of concentric grooves, depressions or protuberances. The nonplanar surface may be shaped as a section of a conic surface so that in the radial direction the spacing between the damping plate surface and its associated disk surface varies linearly. For the disk surfaces facing the top and bottom of the disk housing, the nonplanar surfaces are applied to the top and bottom of the disk housing.