Dynamic write field test for a perpendicular recording head

Patent metadata

Field	Value
Publication number	US-9928881-B1
Application number	US-201715711790-A
Country	US
Kind code	B1
Filing date	Sep 21, 2017
Priority date	Sep 21, 2017
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A method of testing a dynamic write field of a recording head includes preparing a test magnetic medium and recording a write signal on the test magnetic medium with the write signal being set at a first write parameter and a second write parameter. An average of multiple read-back signals of the recorded write signal are captured to determine an average amplitude of the read-back signals. The recording of the write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal are repeated to determine the average amplitude of the read-back signals by fixing the first write parameter of the write signal and changing the second write parameter of the write signal until the average amplitude of the read-back signals saturates.

First claim

What is claimed is:

1. A method of testing a dynamic write field of a recording head, the method comprising:
preparing a test magnetic medium;
recording a write signal on the test magnetic medium with the write signal being set at a first write parameter and a second write parameter;
capturing an average of multiple read-back signals of the recorded write signal to determine an average amplitude of the read-back signals, wherein the average amplitude of the read-back signals is related to write current; and
repeating the recording of the write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal to determine the average amplitude of the read-back signals by fixing the first write parameter of the write signal and changing the second write parameter of the write signal until the average amplitude of the read-back signals saturates.

2. The method of claim 1 , further comprising calculating a rise time of the write signal based on when the average amplitude of the read-back signals saturate, wherein the rise time is comprises a first rise time.

3. The method of claim 2 , further comprising verifying the calculated first rise time of the write signal by resetting the write signal to the first write parameter and the second write parameter and performing the steps of:
recording a verification write signal on the test magnetic medium with the verification write signal being set at the first write parameter and the second write parameter;
capturing an average of multiple read-back signals of the recorded verification write signal to determine an average amplitude of the read-back signals, wherein the average amplitude of the read-back signals is related to write current; and
repeating the recording of the verification write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal to determine the average amplitude of the read-back signals by changing the first write parameter of the write signal and fixing the second write parameter of the write signal until the average amplitude of the read-back signals saturates.

4. The method of claim 3 , further comprising calculating a verification rise time of the verification write signal based on when the average amplitude of the read-back signals saturate, wherein the verification rise time comprises a second rise time.

5. The method of claim 4 , further comprising comparing the first rise time to the second rise time to verify accuracy of the first rise time.

6. The method of claim 1 , wherein the first write parameter of the write signal comprises one of a pulse width and an amplitude of the write current.

7. The method of claim 6 , wherein the second write parameter of the write signal is different from the first write parameter and comprises one of the pulse width and the amplitude of the write current.

8. The method of claim 7 , wherein the amplitude of the write current comprises an overshoot amplitude of the write current.

9. A method of testing a dynamic write field of a recording head, the method comprising:
preparing a test magnetic medium;
recording a write signal on the test magnetic medium with the write signal being set at an amplitude of a write current and a pulse width;
capturing an average of multiple read-back signals of the recorded write signal to determine an average amplitude of the read-back signals, wherein the average amplitude of the read-back signals is related to write current; and
repeating the recording of the write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal to determine the average amplitude of the read-back signals by fixing the amplitude of the write current and changing the pulse width of the write signal until the average amplitude of the read-back signals saturates.

10. The method of claim 9 , further comprising calculating a rise time of the write signal based on when the average amplitude of the read-back signals saturate, wherein the rise time is comprises a first rise time.

11. The method of claim 10 , further comprising verifying the calculated first rise time of the write signal by resetting the amplitude of the write current and the pulse width of the write signal and performing the steps of:
recording a verification write signal on the test magnetic medium with the verification write signal being set at the amplitude of the write current and the pulse width;
capturing an average of multiple read-back signals of the recorded verification write signal to determine an average amplitude of the read-back signals at the amplitude of the write signal and the pulse width of the write signal, wherein the average amplitude of the read-back signals is related to write current; and
repeating the recording of the verification write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal to determine the average amplitude of the read-back signals by changing the amplitude of the write current and fixing the pulse width of the write signal until the average amplitude of the read-back signals saturates.

12. The method of claim 11 , further comprising calculating a verification rise time of the verification write signal based on when the average amplitude of the read-back signals saturate, wherein the verification rise time comprises a second rise time.

13. The method of claim 12 , further comprising comparing the first rise time to the second rise time to verify accuracy of the first rise time.

14. The method of claim 9 , wherein the amplitude of the write current comprises an overshoe amplitude of the write current.

15. A method of testing a dynamic write field of a recording head, the method comprising:
preparing a test magnetic medium;
recording a write signal on the test magnetic medium with the write signal being set at a pulse width and an amplitude of a write current;
capturing an average of multiple read-back signals of the recorded write signal to determine an average amplitude of the read-back signals, wherein the average amplitude of the read-back signals is related to write current; and
repeating the recording of the write signal on the test magnetic medium and the capturing of the average of multiple read-back signals of the recorded write signal to determine the average amplitude of the read-back signals by fixing the pulse width of the write signal and changing the amplitude of the write current until the average amplitude of the read-back signals saturates.

16. The method of claim 15 , further comprising calculating a rise time of the write signal based on when the average amplitude of the read-back signals saturate, wherein the rise time is comprises a first rise time.

17. The method of claim 16 , further comprising verifying the calculated first rise time of the write signal by resetting the pulse width of the write signal and the amplitude of the write current and performing the steps of:
recording a verification write signal on the test magnetic medium with the verification write signal being set at the pulse width and the amplitude of the write current;
capturing an average of multiple read-back signals of the recorded verification write signal to determine an average amplitude of the read-back signals, wherein the average amplitude of the read-back signals is related to write current; and
repeating the recording of the verification write signal on the test magnetic medium and the cap

Assignees

• Seagate Technology Llc

Inventors

• Shen Zhe
• Lin Zuxuan
• Lu Lei
• Xue Jianhua

Classifications

• G11B5/4555

  by using a spin-stand, i.e. a spinning disc or simulator · CPC title

• G11B5/012

  Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence) · CPC title

• G11B5/09

  Digital recording · CPC title

• G11B2005/0013

  of transducers, e.g. linearisation, equalisation · CPC title

• G11B20/10481

  optimisation methods · CPC title