Systems and methods for identifying problems with PZT elements of micro-actuators

• US 7,768,276 B2
• Filed: 11/06/2006
• Issued: 08/03/2010
• Est. Priority Date: 11/06/2006
• Status: Expired due to Fees

• Current Assignee: SAE Magnetics Limited (TDK Corporation)
• Original Assignee: SAE Magnetics Limited (TDK Corporation)
• Inventors: Yao, MingGao
• Primary Examiner(s): NGUYEN, HOAI AN D
• Application Number:
  US11/593,169
• Publication Number:
  US 20080106823A1
• Time in Patent Office: 1,366 Days
• Field of Search: 324/652, 324/649, 324/600, 324/727, 324/109, 324/76.11, 324/76.49, 360/294.4, 360/245, 735/79, 310/311, 310/314, 310/317
• US Class Current: 324/727
• CPC Class Codes: G11B 19/048 Testing of disk drives, e.g. to detect defects or prevent sudden failure
• CPC Class Codes: G11B 5/4826 Mounting, aligning or attachment of the transducer head relative to the arm assembly, e.g. slider holding members, gimbals, adhesive G11B5/484 takes precedence; details of head housings or structures G11B5/10, G11B5/127; adjustment relative to the record carrier G11B5/56
• CPC Class Codes: G11B 5/4873 the arm comprising piezoelectric or other actuators for adjustment of the arm
• CPC Class Codes: G11B 5/5552 using fine positioning means for track acquisition separate from the coarse (e.g. track changing) positioning means

Abstract

Systems and methods for identifying problems with PZT elements of micro-actuators are provided. In certain example embodiments, a voltage (e.g., a sine voltage) may be applied to a reference unit causing it as well as a test unit to vibrate. Characteristics of the respective resonances (e.g., frequency, amplitude, phase, etc.) may be compared (e.g., by a processor) to determine whether there are problems with the test unit. The reference unit may include an HGA or an HSA of a hard disk drive device. The test unit may include corresponding parts for inspection. Such techniques make it possible to detect problems with PZT elements when there is only one PZT element per micro-actuator.

Claims

1. A system for identifying problems with a PZT element of a micro-actuator, comprising:

a voltage driver operably connected to a reference micro-actuator, the voltage driver being configured to cause the reference micro-actuator to vibrate at a reference resonance;

a test micro-actuator, configured to vibrate at a test resonance when induced by vibrations from the reference micro-actuator; and

,

a processor, configured to compare at least one characteristic of the reference resonance and at least one corresponding characteristic of the test resonance.

2. The system of claim 1, wherein the voltage driver is configured to apply a sine voltage to the reference micro-actuator.

3. The system of claim 1, wherein the at least one characteristic of the reference resonance and the at least one corresponding characteristic of the test resonance are one or more of:

frequency, amplitude, and phase.

4. The system of claim 1, wherein each micro-actuator is located within a disk drive device, the disk drive device comprising:

a head stack assembly including a plurality of head gimbal assemblies, each head gimbal assembly having a slider with a read/write head thereon and a drive arm connected to the head gimbal assembly;

a disk operable to be read from and/or written to by said read/write head; and

,

a spindle motor operable to spin the disk.

5. The system of claim 4, wherein the reference micro-actuator is one micro-actuator in the head stack assembly, and wherein all other micro-actuators are test micro-actuators.

6. A method for identifying problems with a PZT element of a micro-actuator, the method comprising:

providing a reference micro-actuator and a test micro-actuator;

applying a voltage to the reference micro-actuator to induce a reference resonance in the reference micro-actuator, the reference resonance causing a test resonance in the test micro-actuator;

measuring the reference resonance and the test resonance; and

,

comparing at least one characteristic of the reference resonance and at least one corresponding characteristic of the test resonance.

7. The method of claim 6, further comprising determining whether there is a problem with the test micro-actuator based on the comparing step.

8. The method of claim 6, wherein the voltage is a sine voltage.

9. The method of claim 6, wherein the at least one characteristic of the reference resonance and at the least one corresponding characteristic of the test resonance are one or more of:

frequency, amplitude, and phase.

10. A method for identifying problems with a PZT element of a micro-actuator of a disk drive device including a head stack assembly including a plurality of head gimbal assemblies, each head gimbal assembly having a slider with a read/write head thereon and a drive arm connected to the head gimbal assembly, the method comprising:

applying a voltage to the head stack assembly to induce resonances in each micro-actuator;

measuring the induced resonances in each micro-actuator;

generating a reference resonance; and

,

comparing at least one characteristic of the induced resonances with at least one corresponding characteristic of the reference resonance.

11. The method of claim 10, further comprising determining whether there is a problem with one or more of the micro-actuators based on the comparing step.

12. The method of claim 10, wherein the voltage is a sine voltage.

13. The method of claim 10, wherein the at least one characteristic of the induced resonances is one or more of:

frequency, amplitude, and phase.

14. The method of claim 10, further comprising estimating the reference resonance based at least in part on the voltage applies.

15. The method of claim 10, further comprising averaging the induced resonances to generate the reference resonance.

16. The method of claim 10, further comprising designating one induced reference as the reference resonance.

17. The method of claim 10, wherein the reference resonance rotates among the induced resonances such that the comparing step includes comparing each induced resonance to every other induced resonance.