Implementing enhanced ESD prevention for hard disk drives using spin-torque oscillator (STO)

• US 8,797,693 B1
• Filed: 08/26/2013
• Issued: 08/05/2014
• Est. Priority Date: 08/26/2013
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Inventors: Furukawa, Masaru, Xu, Junguo, Suzuki, Kenji, Satou, Makoto
• Primary Examiner(s): HINDI, NABIL Z
• Application Number:
  US13/975,660
• Time in Patent Office: 344 Days
• Field of Search: 360/59, 360/128, 360/323, 360/110, 360/125.16
• US Class Current: 360/323
• CPC Class Codes: G11B 2005/0024 Microwave assisted recording
• CPC Class Codes: G11B 5/3106 where the integrated or assembled structure comprises means for conditioning against physical detrimental influence, e.g. wear, contamination G11B5/3133 takes precedence
• CPC Class Codes: G11B 5/6094 Preventing or discharging electrostatic charge build-up on the flying head

Abstract

A method, apparatus, and system are provided for preventing electrostatic discharge (ESD) in hard disk drives using spin-torque oscillator (STO) for microwave assisted magnetic recording (MAMR). A control circuit adjusts a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element. The control circuit maintains a potential difference of less than about 115 millivolts (mV) between the disk and the STO element.

Claims

1. A method for preventing electrostatic discharge (ESD) in hard disk drives using spin-torque oscillator (STO) comprising:

providing control circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element; and

said control circuitry maintaining a potential difference of less than about 115 millivolts (mV) between a disk and the STO element.

2. The method as recited in claim 1 includes providing said spin-torque oscillator (STO) element coupled between a first STO electrode and a second STO electrode, and a preamplifier coupled to said first STO electrode and said second STO electrode.

3. The method as recited in claim 1 wherein providing control circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element includes providing a preamplifier including an STO reference terminal, and said STO reference connected to a potential control circuit, and providing said potential control circuit coupled to a disk spindle supporting the disk.

4. The method as recited in claim 3 wherein providing said potential control circuit coupled to said disk spindle supporting the disk includes providing a wire connecting said STO reference terminal and said potential control circuit.

5. The method as recited in claim 3 includes providing a current-limiting resistance between said potential control circuit and said disk spindle, said current-limiting resistance of at least 10 kilohms (kΩ

).

6. The method as recited in claim 1 wherein providing circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element includes providing said spin-torque oscillator (STO) element coupled between a first STO electrode and a second STO electrode and providing a preamplifier having respective terminals coupled to said first STO electrode and said second STO electrode, and providing one of said respective terminals of said preamplifier coupled to a disk spindle supporting the disk.

7. The method as recited in claim 6 wherein providing one of said respective terminals of said preamplifier coupled to a disk spindle supporting the disk includes providing a current-limiting resistance between said one of said respective terminals of said preamplifier and said disk spindle.

8. The method as recited in claim 1 wherein providing circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element includes providing said spin-torque oscillator (STO) element coupled between a first STO electrode and a second STO electrode and providing a preamplifier having respective terminals coupled to said first STO electrode and said second STO electrode, providing a potential control circuit coupled to a disk spindle supporting the disk, and providing one of said respective terminals of said preamplifier coupled to said potential control circuit.

9. The method as recited in claim 1 wherein providing a potential control circuit coupled to a disk spindle supporting the disk includes providing a current-limiting resistance between said potential control circuit and said disk spindle, said current-limiting resistance of at least 10 kilohms (kΩ

).

10. The method as recited in claim 1 wherein providing circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element includes providing said spin-torque oscillator (STO) element coupled between a first STO electrode and a second STO electrode and providing a preamplifier having respective terminals coupled to said first STO electrode and said second STO electrode, providing a common voltage circuit applying a common mode voltage to said respective terminals of said preamplifier responsive to conduction by said STO element.

11. An apparatus for preventing electrostatic discharge (ESD) in hard disk drives using spin-torque oscillator (STO) comprising:

control circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element; and

said control circuitry maintaining a potential difference of less than about 115 millivolts (mV) between the disk and the STO element.

12. The apparatus as recited in claim 11 wherein said control circuitry includes said spin-torque oscillator (STO) element coupled between a first STO electrode and a second STO electrode, and said control circuitry includes a preamplifier having respective terminals coupled to said first STO electrode and said second STO electrode.

13. The apparatus as recited in claim 12 wherein said control circuitry includes said preamplifier including an STO reference terminal, and said STO reference connected to a potential control circuit, said potential control circuit coupled to a disk spindle supporting the disk, and a current-limiting resistance coupled between said potential control circuit and said disk spindle.

14. The apparatus as recited in claim 12 wherein said control circuitry includes one of said respective terminals of said preamplifier coupled to a disk spindle supporting the disk, and a current-limiting resistance coupled between said one of said respective terminals of said preamplifier and said disk spindle.

15. The apparatus as recited in claim 12 wherein said control circuitry includes one of said respective terminals of said preamplifier coupled to a potential control circuit, said potential control circuit coupled to a disk spindle supporting the disk, and a current-limiting resistance coupled between said potential control circuit and said disk spindle.

16. The apparatus as recited in claim 12 wherein said control circuitry includes a common voltage circuit applying a common mode voltage to said respective terminals of said preamplifier responsive to conduction by said STO element.

17. A system for preventing electrostatic discharge (ESD) in hard disk drives using spin-torque oscillator (STO) comprising:

at least one disk for storing data;

a slider including a spin-torque oscillator (STO) element;

said spin-torque oscillator (STO) element coupled between a first STO electrode and a second STO electrode;

control circuitry for adjusting a disk electrical potential with an electrical potential of a spin-torque oscillator (STO) element; and

said control circuitry maintaining a potential difference of less than about 115 millivolts (mV) between the disk and the STO element.

18. The system as recited in claim 17 wherein said control circuitry includes a preamplifier having respective terminals coupled to said first STO electrode and said second STO electrode.

19. The system as recited in claim 18 wherein said preamplifier includes an STO reference terminal, and said STO reference connected to a potential control circuit, said potential control circuit coupled to a disk spindle supporting the disk, and a current-limiting resistance coupled between said potential control circuit and said disk spindle.

20. The system as recited in claim 18 wherein said control circuitry includes one of said respective terminals of said preamplifier coupled to a disk spindle supporting the disk, and a current-limiting resistance coupled between said one of said respective terminals of said preamplifier and said disk spindle.