Magnetic disk apparatus

Abstract

Magnetic disk apparatus includes a magnetic head element having a read element and a write element, a heater provided in the magnetic head element for controlling a protruding amount thereof, a write resistance detector that detects a resistance value of the write element, and an MPU (write element temperature calculation unit) that calculates a temperature of the write element as a temperature of the magnetic head element based on a resistance value of the write element detected by the write resistance detector and a temperature coefficient of the write element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of a structure of a magnetic disk apparatus.

FIG. 2 is a diagram showing an example of a structure of a MPU.

FIG. 3 is a diagram showing an example of an electric power/current control table.

FIG. 4 is a diagram showing a magnetic head and a HDIC of the magnetic disk apparatus.

FIGS. 5A and 5B are diagrams showing an example in which a certain cross-section of the magnetic head is viewed from the side and an example in which a top of the magnetic head is viewed from above.

FIG. 6A and 6B are diagrams showing a cross-section of the magnetic head element for describing protrusion control for the magnetic head element.

FIG. 7 is a diagram showing the dependence of a write element resistance value on temperature.

FIG. 8 is a diagram showing an example of a process flowchart to set a resistance value of a write element at 25° C. and control selection information before shipment of the magnetic disk apparatus.

FIG. 9 is a diagram showing an example of a process flowchart to control a heater power, a sense current and a write current.

Claims

1. A magnetic disk apparatus, comprising: a magnetic head element including a read element and a write element;a heater provided in the magnetic head element and controlling a protruding amount of the magnetic head element;a resistance detection unit detecting a resistance value of the write element; anda write element temperature calculation unit calculating a temperature of the write element as a temperature of the magnetic head element based on the resistance value of the write element detected by the resistance detection unit and a temperature coefficient of the write element.

2. The magnetic disk apparatus according to claim 1, further comprising: a heater power control unit controlling a heater power supplied to the heater based on the temperature of the write element calculated by the write element temperature calculation unit.

3. The magnetic disk apparatus according to claim 2, wherein, when the temperature of the write element calculated by the write element temperature calculation unit is equal to or greater than a predetermined value, the heater power control unit suppresses the heater power supplied to the heater.

4. The magnetic disk apparatus according to claim 1, further comprising: a sense current control unit controlling a sense current supplied to the read element based on the temperature of the write element calculated by the write element temperature calculation unit.

5. The magnetic disk apparatus according to claim 4, wherein the sense current control unit sets a sense current supplied to the read element in response to the temperature of the write element calculated by the write element temperature calculation unit.

6. The magnetic disk apparatus according to claim 1, further comprising: a write current control unit controlling a write current supplied to the write element based on the temperature of the write element calculated by the write element temperature calculation unit.

7. The magnetic disk apparatus according to claim 6, wherein the write current control unit sets a write current supplied to the write element in response to the temperature of the write element calculated by the write element temperature calculation unit.

8. The magnetic disk apparatus according to claim 1, further comprising: a control unit performing control of the heater power, control of the sense current, or control of the write current based on the temperature of the write element calculated by the write element temperature calculation unit and a preset control selection information that indicates which control to be performed among control of a heater power to be supplied to the heater, control of a sense current to be supplied to the read element and control of a write current to be supplied to the write element.

9. The magnetic disk apparatus according to claim 1, wherein the write element temperature calculation unit further calculates the temperature of the write element using a preset resistance value of the write element at an ordinary temperature.

10. The magnetic disk apparatus according to claim 1, further comprising: a temperature sensor detecting an internal temperature of the magnetic disk apparatus,wherein the write element temperature calculation unit further calculates the temperature of the write element using the internal temperature detected by the temperature sensor, a preset resistance value of a magnetic head circuit at an ordinary temperature, and a preset temperature coefficient of the magnetic head circuit.