Techniques for reducing dynamic coupling of system modes in a dual actuator hard disk drive

Patent metadata

Field	Value
Publication number	US-10186286-B2
Application number	US-201715616804-A
Country	US
Kind code	B2
Filing date	Jun 7, 2017
Priority date	Jun 7, 2017
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

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.

First claim

What is claimed is:

1. A data storage device comprising:
a plurality of recording disk media rotatably mounted on a spindle;
a first head slider comprising a read-write transducer configured to read from and to write to one disk media of said plurality of disk media;
a first rotary actuator assembly configured to move said first head slider to access portions of said one disk media;
a second head slider comprising a read-write transducer configured to read from and to write to another disk media of said plurality of disk media;
a second rotary actuator assembly configured to move said second head slider to access portions of said another disk media; and
a shaft around which said first rotary actuator assembly is rotatably coupled, with a first bearing assembly interposed therebetween with a first particular bearing preload, at a first location of said shaft and said second rotary actuator assembly is rotatably coupled, with a second bearing assembly interposed therebetween with a second particular bearing preload, at a second location of said shaft;
wherein said first particular bearing preload is intentionally different from said second particular bearing preload.

2. The data storage device of claim 1 , wherein said first bearing assembly and said second bearing assembly are similarly constructed parts, and wherein a stiffness of said first bearing assembly is based on said first particular bearing preload and a stiffness of said second bearing assembly is based on said second particular bearing preload, and thereby said stiffness of said first bearing assembly is different from said stiffness of said second bearing assembly.

3. The data storage device of claim 2 , wherein each of said first and second bearing assemblies comprises a pair of equivalent bearings.

4. The data storage device of claim 3 , wherein said first bearing assembly comprises a first bearing spacing and said second bearing assembly comprises a second bearing spacing that is different from the first bearing spacing.

5. The data storage device of claim 1 , wherein said first rotary actuator assembly and said second rotary actuator assembly comprise similarly constructed parts.

6. The data storage device of claim 1 , wherein said first particular bearing preload corresponds to a first structural resonance mode of said first rotary actuator assembly and said second particular bearing preload corresponds to a second structural resonance mode of said second rotary actuator assembly, and wherein said first particular bearing preload and said second particular bearing preload are such that a first frequency corresponding to said first structural resonance mode is separated from a second frequency corresponding to said second structural resonance mode.

7. The data storage device of claim 6 , wherein said first particular bearing preload and said second particular bearing preload are such that a gain corresponding to a coupling transfer function between said first and second rotary actuator assemblies is less than would otherwise be in an actuator system in which said first and second bearing preloads are equivalent.

8. The data storage device of claim 6 , wherein each of said first structural resonance mode and said second structural resonance mode is a butterfly mode.

9. A hard disk drive actuator pivot assembly comprising:
a lower bearing assembly having a first particular preload;
an upper bearing assembly having a second particular preload different from said first particular preload;
wherein each of said lower and upper bearing assemblies comprises a pair of substantially identical bearing mechanisms;
wherein said lower bearing assembly comprises a lower bearing span and said upper bearing assembly comprises an upper bearing span that is different from the lower bearing span;
a lower voice coil actuator assembly, wherein said lower bearing assembly is interposed between a shared pivot shaft and said lower voice coil actuator assembly; and
an upper voice coil actuator assembly, wherein said upper bearing assembly is interposed between said shared pivot shaft and said upper voice coil actuator assembly;
wherein said lower voice coil actuator assembly and said upper voice coil actuator assembly comprise similarly configured components.

10. The hard disk drive actuator pivot assembly of claim 9 , wherein a stiffness of said lower bearing assembly is based on said first particular preload and a stiffness of said upper bearing assembly is based on said second particular preload, and thereby said stiffness of said lower bearing assembly is different from said stiffness of said upper bearing assembly.

11. The hard disk drive actuator pivot assembly of claim 9 , wherein said first particular preload corresponds to a structural resonance mode of said lower voice coil actuator assembly and said second particular preload corresponds to a structural resonance mode of said upper voice coil actuator assembly, and wherein said first particular preload and said second particular preload are such that a frequency at which said structural resonance mode of said lower voice coil actuator assembly occurs is intentionally different from a frequency at which said structural resonance mode of said upper voice coil actuator assembly occurs.

12. The hard disk drive actuator pivot assembly of claim 9 , wherein said lower and upper voice coil actuator assemblies, said lower and upper bearing assemblies, and said shared pivot shaft compose an actuator system, and wherein said first particular preload and said second particular preload are such that a gain corresponding to a coupling transfer function in said actuator system is less than would otherwise be in an actuator system in which said first and second preloads are equivalent.

13. A hard disk drive comprising the actuator pivot assembly of claim 9 .

14. A hard disk drive dual-actuator shared shaft assembly comprising:
a lower actuator assembly coupled with said shared shaft; and
an upper actuator assembly coupled with said shared shaft; and
means for separating a structural resonance mode frequency corresponding to said lower actuator assembly from a structural resonance mode frequency corresponding to said upper actuator assembly.

15. The hard disk drive dual-actuator shared shaft assembly of claim 14 , wherein each of said structural resonance mode frequency corresponding to said lower actuator assembly and said structural resonance mode frequency corresponding to said upper actuator assembly is a butterfly mode of vibration.

16. The hard disk drive dual-actuator shared shaft assembly of claim 14 , wherein each of said structural resonance mode frequency corresponding to said lower actuator assembly and said structural resonance mode frequency corresponding to said upper actuator assembly is a rocking mode of vibration.

17. A method for manufacturing an actuator pivot assembly, the method comprising:
assembling a first actuator assembly onto an actuator pivot shaft with a first bearing assembly interposed therebetween, wherein said first bearing assembly has a particular first preload applied thereto, thereby affecting a structural resonance frequency of said first actuator assembly; and
assembling a second actuator assembly onto said actuator pivot shaft with a second bearing assembly interposed therebetween, wherein said second bearing assembly has a second internationally different particular preload applied thereto, thereby affecting a structural resonance frequency of said second actuator assembly.

18. The method of claim 17 , wherein said first

Assignees

• Western Digital Tech Inc

Inventors

• Keshavan Manoj

Classifications

• G11B5/5578

  Multiple actuators addressing the same disk, e.g. to improve data rate or access rate · CPC title

• G11B5/5521

  across disk tracks (spiral track following G11B5/596) · CPC title

• G11B5/4813 Primary

  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 title

• G11B5/59622

  Gain control; Filters · CPC title

• G11B5/531 Primary

  Disposition of more than one recording or reproducing head on support rotating cyclically around an axis · CPC title