Media drive and control method for the same

Abstract

Embodiments in accordance with the present invention relate to improving error recovery process performance. A head slider in an embodiment of this invention includes a heater for adjusting a clearance between a head element section and a magnetic disk. During an error recovery process (ERP) for a reading error, if a particular environmental temperature is in a low-temperature region, a microprocessing unit (MPU) executes the ERP steps of increasing a heater power value of the heater (i.e., STEP X to STEP X+2), preferentially over the ERP steps of reducing the heater power (i.e., STEP X+3 to STEP X+5). In the low-temperature region, the possibility of error recovery in an earlier step can be raised by executing the heater power increasing ERP steps earlier than the heater power reducing ERP steps.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing schematically a total configuration of an HDD according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a construction of a head slider which has a heater for TFC according to an embodiment of the present invention.

FIG. 3 is a block diagram showing schematically a logical configuration associated with a reading ERP according to an embodiment of the present invention.

FIG. 4 is a diagram showing schematically an example of a reading ERP table relating to a normal-temperature region according to an embodiment of the present invention.

FIG. 5 is a diagram showing schematically an example of a reading ERP table relating to a low-temperature region according to an embodiment of the present invention.

FIG. 6 is a diagram showing schematically an example of a high-temperature region reading ERP table according to an embodiment of the present invention.

FIG. 7 is a block diagram showing schematically a logical configuration associated with a writing ERP according to an embodiment of the present invention.

FIG. 8 is a diagram showing schematically an example of a writing ERP table for a ‘velocity-based write abort’ error according to an embodiment of the present invention.

FIG. 9 is a diagram showing schematically an example of a writing ERP table for a ‘servo VGA abort’ error according to an embodiment of the present invention.

FIG. 10 is a diagram schematically showing a structure of a magnetoresistive element according to an embodiment of the present invention.

FIGS. 11( a) and 11(b) are graphs that show deterioration of instability due to TFC.

FIG. 12 is a diagram schematically showing a writing current waveform according to an embodiment of the present invention.

FIGS. 13( a) and 13(b) are diagrams schematically showing a data format of a servo pattern according to an embodiment of the present invention.

FIG. 14 is a graph that shows characteristics quantities of a reading signal waveform used for instability judgment.

Claims

1. A media drive comprising: a slider that flies above a rotating medium;a head element section disposed in the slider;a heater disposed in the slider, wherein the heater causes the head element section to protrude by thermal expansion and adjusts a clearance between the medium and the head element section;a table which, if an error occurs, identifies an execution step of an error recovery process for the error, wherein the table includes a step of changing the heater in heater power; anda controller that conducts execution control of the execution step identified by the table.

2. The media drive according to claim 1, further comprising a temperature detector, wherein, in accordance with a temperature detected by the temperature detector, the drive changes the heater power changing step to be executed in the error recovery process.

3. The media drive according to claim 1, further comprising a temperature detector, wherein, in accordance with a temperature detected by the temperature detector, the drive changes execution priority of the heater power changing step in the error recovery process.

4. The media drive according to claim 1, further comprising a temperature detector, wherein, in an error recovery process for a reading error, if a temperature detected by the temperature detector is lower than a reference temperature, the table identifies the step of increasing the heater power, as an execution step.

5. The media drive according to claim 4, wherein, the table identifies the step of increasing the heater power and the step of reducing the heater power, as execution steps; andexecution priority of the step of increasing the heater power is higher than execution priority of the step of reducing the heater power.

6. The media drive according to claim 1, further comprising a temperature detector, wherein, in an error recovery process for a reading error, if a temperature detected by the temperature detector is higher than a reference temperature, the table identifies the step of reducing the heater power, as an execution step.

7. The media drive according to claim 6, wherein, the table identifies the step of increasing the heater power and the step of reducing the heater power, as execution steps; andexecution priority of the step of reducing the heater power is higher than execution priority of the step of increasing the heater power.

8. The media drive according to claim 1, wherein, in accordance with the type of error, the drive changes the heater power changing step to be executed in the error recovery process.

9. The media drive according to claim 8, wherein, in an error recovery process for a writing error during data writing onto the medium, the table identifies the step of reducing the heater power, as an execution step.

10. The media drive according to claim 8, wherein, in an error recovery process for an error whose servo data reading signal level during a writing process is lower than a reference level, the table identifies the step of increasing the heater power, as an execution step.

11. The media drive according to claim 10, wherein, in accordance with the servo data reading signal level, the drive determines the heater power in the execution step.

12. The media drive according to claim 1, wherein the table changes a writing current waveform so as to reduce strength of a magnetic field generated and increases the heater power so as to compensate for a decrease in calorific value due to the change in the waveform.

13. The media drive according to claim 1, wherein the controller judges whether instability of the head element section is in excess of a reference value, and if the reference value is judged to be exceeded, raises an execution priority level of the step of changing the heater power.

14. The media drive according to claim 13, wherein the controller raises execution priority of the heater power reducing step to a level higher than execution priority of the heater power increasing step.

15. A method of controlling a media drive including a slider which flies above a rotating medium, a head element section which is disposed in the slider, and a heater which is disposed in the slider, makes the head element section protrude by thermal expansion, and adjusts a clearance between the medium and the head element section, the control method comprising: if an error occurs, referring to a table that identifies an execution step of an error recovery process for the error; andin the error recovery process, executing the step identified by the table in order to change the heater in heater power.

16. The method according to claim 15, further comprising, in accordance with a detected temperature, changing the heater power changing step to be executed in the error recovery process.

17. The method according to claim 15, further comprising, in accordance with a detected temperature, changing execution priority of the heater power changing step to be executed in the error recovery process.

18. The method according to claim 15, further comprising, in accordance with the type of error, changing the heater power changing step to be executed in the error recovery process.

19. A media drive comprising: a slider that flies above a rotating medium;a head element section disposed in the slider;a heater disposed in the slider, wherein the heater causes the head element section to protrude by thermal expansion and adjusts a clearance between the medium and the head element section; anda controller that judges whether instability of the head element section is in excess of a reference value, and if the reference value is judged to be exceeded, adjusts the power supplied to the heater.

20. The media drive according to claim 19, wherein the controller judges the instability on the basis of an error rate of data read out by the head element section.

21. The media drive according to claim 19, wherein the controller judges the instability on the basis of an execution rate of error recovery processes with respect to data reading operations and/or an execution rate of specific steps in an error recovery process.

22. The media drive according to claim 19, wherein the controller judges the instability on the basis of an error rate of registered servo data read out from the medium by the head element section.

23. The media drive according to claim 19, wherein the controller judges the instability in accordance with amplitude and/or symmetry of a waveform of a signal from a reading element of the head element section.

24. The media drive according to claim 19, wherein: the instability is judged using at least any two criteria of all those which include an error rate of data read out by the head element section, an execution rate of error recovery processes with respect to data reading operations and/or an execution rate of specific steps in an error recovery process, an error rate of registered servo data read out from the medium by the head element section, and amplitude and/or symmetry of a waveform of a signal from a reading element of the head element section; andif the required plurality of judgment criteria are all overstepped, the controller judges that the instability of the head element section is outside an allowable range.