Granted Patent B1

US 9,123,370 · App. 14/578,054 · Granted Sep 1, 2015

Inventors: Huanxiang Ruan (Irvine, CA); Galvin T. Chia (Rancho Santa Margarita, CA)

Assignee: Western Digital Technologies, Inc.

G11B5/6052G11B13/04G11B2005/0021

Abstract

Claims (30)

1. A data storage device comprising:

a disk;

a head comprising a laser configured to heat the disk while writing data to the disk;

a fly height actuator (FHA) configured to actuate the head vertically over the disk based on an FHA setting; and

control circuitry configured to:

calibrate a write laser power applied to the laser during a write operation;

measure a first fly height of the head at a first laser power setting;

measure a second fly height of the head at a second laser power setting different from the first laser power setting; and

generate a FHA write setting based on the calibrated write laser power, the first and second fly height measurements, and a first function representing a nominal FHA delta setting between a read touchdown FHA setting and a write touchdown FHA setting relative to a delta in a fly height of the head due to a corresponding change in laser power applied to the laser, where the FHA write setting is applied to the FHA during the write operation.

2. The data storage device as recited in claim 1 , wherein the first function comprises a second order polynomial.

3. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:

generate a second function representing the delta in fly height of the head relative to the laser power applied to the laser; and

generate the FHA write setting based on the second function.

4. The data storage device as recited in claim 3 , wherein the second function comprises a linear function.

5. The data storage device as recited in claim 3 , wherein the control circuitry is further configured to:

compute a calibrated delta in the fly height with the calibrated write laser power as an input to the second function; and

compute the FHA write setting with the calibrated delta in the fly height as an input to the first function.

6. A method of operating a data storage device, the method comprising:

calibrating a write laser power applied to a laser of a head during a write operation;

measuring a first fly height of the head over a disk at a first laser power setting;

measuring a second fly height of the head at a second laser power setting different from the first laser power setting; and

generating a fly height actuator (FHA) write setting based on the calibrated write laser power, the first and second fly height measurements, and a first function representing a nominal FHA delta setting between a read touchdown FHA setting and a write touchdown FHA setting relative to a delta in a fly height of the head due to a corresponding change in laser power applied to the laser, where the FHA write setting is applied to the FHA during the write operation.

7. The method as recited in claim 6 , wherein the first function comprises a second order polynomial.

8. The method as recited in claim 6 , further comprising:

generating a second function representing the delta in fly height of the head relative to the laser power applied to the laser; and

generating the FHA write setting based on the second function.

9. The method as recited in claim 8 , wherein the second function comprises a linear function.

10. The method as recited in claim 8 , further comprising:

computing a calibrated delta in the fly height with the calibrated write laser power as an input to the second function; and

computing the FHA write setting with the calibrated delta in the fly height as an input to the first function.

Assignments (8)

Continuity (1)