JP2010257532A - Magnetic disk device, frictional force measurement method and magnetic disk control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a frictional force between a head slider and a magnetic disk without adding any new component, and to adjust the frictional force within an appropriate range. <P>SOLUTION: Piezoelectric elements 8 and 9 for adjusting the position of a contact head slider 6 that reads or write data from/to a magnetic disk 10, in contact with the magnetic disk 10, are provided as sub-actuators. By using the piezoelectric elements, a frictional force generated between the head slider and the magnetic disk is measured. According to the measured frictional force, a thermal actuator included in the head slider is adjusted, and the contact force of the head slider with the magnetic disk is adjusted. Thus, the frictional force generated between the head slider and the magnetic disk is adjusted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic disk device, a friction force measuring method, and a magnetic disk control device.

  In recent years, magnetic disk devices such as HDDs (Hard Disk Drives) store high-density magnetic information in order to store a large amount of information. For this reason, the head slider of the magnetic disk device performs reading processing and writing processing close to the magnetic disk in order to perform accurate reading processing and writing processing on high-density magnetic information.

  There is also known a magnetic disk device that employs a contact slider system in which a head slider is brought into contact with a magnetic disk to read and write magnetic information. Here, in a magnetic disk using a contact slider, an excessive frictional force may be generated between the head slider and the magnetic disk and may be damaged.

  Therefore, a technique is known in which a frictional force sensor that measures the frictional force generated between the head slider and the magnetic disk is installed to maintain a contact state that does not generate excessive frictional force (see, for example, Patent Document 1). ). Further, a technique is known in which a sensor for measuring a frictional force generated between a head slider and a magnetic disk is installed in a magnetic disk device, and the installed sensor measures the frictional force (see, for example, Patent Document 2). .

  Further, the magnetic disk device has an actuator that moves the head slider by a minute distance. Such a magnetic disk device has, for example, a main actuator that moves the head slider stepwise and a subactuator that adjusts the minute position of the head slider (see, for example, Patent Document 3).

  As a magnetic disk device having such a sub-actuator, a technique for detecting contact between a flying head slider and a magnetic disk using a sub-actuator using a piezoelectric element is known (for example, see Patent Document 4). Specifically, the magnetic disk device observes the voltage of the sub-actuator and detects the voltage generated by the sub-actuator when the head slider and the magnetic disk come into contact with each other. When the magnetic disk device detects contact between the head slider and the magnetic disk, the magnetic disk device retracts the head slider from the magnetic disk.

Japanese Patent Laid-Open No. 08-07511 JP 07-85575 A Japanese Patent No. 3771122 JP 2002-15537 A

  However, the technique of detecting the contact between the head slider and the magnetic disk using the sub-actuator described above detects the contact between the head slider and the magnetic disk, but cannot measure the generated frictional force. As a result, the magnetic disk device cannot adjust the frictional force generated between the head slider and the magnetic disk, and there is a problem that the HDD is deteriorated.

  Further, in the technology for measuring the frictional force using the above-described sensor, it is necessary to install a sensor for measuring the frictional force generated between the magnetic disk and the head slider, so that the structure of the magnetic disk device is complicated. There was a problem of becoming.

  Therefore, the magnetic disk device disclosed in the present application is intended to solve the above-described problems, and the frictional force between the head slider and the magnetic disk is appropriately set without complicating the structure of the magnetic disk device. Provided are a magnetic disk device, a friction force measuring method, and a magnetic disk control device that are adjusted so as to fall within a certain range.

  According to one aspect of the technology disclosed in the present application, a frictional force is measured using a voltage generated in a piezoelectric element that adjusts the position of a head slider.

  According to one aspect of the technology disclosed in the present application, the frictional force between the magnetic disk and the head slider can be measured using the voltage generated in the piezoelectric element that adjusts the position of the head slider.

FIG. 1 is a diagram illustrating the magnetic disk device according to the first embodiment. FIG. 2 is a diagram for explaining a head portion of the magnetic disk apparatus according to the first embodiment. FIG. 3 is a diagram illustrating the subactuator according to the first embodiment. FIG. 4 is a block diagram illustrating the magnetic disk device according to the first embodiment. FIG. 5 is a diagram for explaining the subactuator of the magnetic disk device according to the first embodiment. FIG. 6 is a diagram (1) for explaining the frictional force generated between the head slider and the magnetic disk according to the first embodiment. FIG. 7 is a diagram (2) for explaining the frictional force generated between the head slider and the magnetic disk according to the first embodiment. FIG. 8 is a diagram for explaining the DFH of the head slider according to the first embodiment. FIG. 9 is a diagram for explaining the relationship among the frictional force, DFH, and vibration of the head slider according to the first embodiment. FIG. 10 is a flowchart for explaining the flow of processing for adjusting the frictional force of the magnetic disk apparatus according to the first embodiment. FIG. 11 is a flowchart for explaining the flow of tracking processing according to the first embodiment. FIG. 12 is a diagram (1) for explaining the position of the sub-actuator. FIG. 13 is a diagram (2) for explaining the position of the sub-actuator.

  Embodiments of a magnetic disk device and a friction force measuring method according to the present invention will be described below in detail with reference to the accompanying drawings.

  In the following embodiments, the configuration of the magnetic disk device and the flow of processing will be described in order. First, the configuration of the magnetic disk device according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating the magnetic disk device according to the first embodiment.

  A magnetic disk device 1 according to the first embodiment includes a controller 2, a main arm 3, a voice coil motor 4, a head suspension 5, a head slider 6, a ramp 7, and a magnetic disk 10.

  The controller 2 operates the main arm 3 using the voice coil motor 4. Further, the controller 2 adjusts the position of the head slider 6 using a piezoelectric element 8 and a piezoelectric element 9 which will be described later. In addition, the controller 2 uses the piezoelectric element 8 and the piezoelectric element 9 to measure the frictional force generated between the magnetic disk 10 and the head slider 6. The controller 2 uses the head slider 6 to read and write magnetic information recorded on the magnetic disk 10.

  The main arm 3 supports a head suspension 5 and a head slider 6. The voice coil motor 4 is connected to the main arm 3 and drives the main arm 3. The head suspension 5 is a cushioning component that supports the head slider 6.

  The head slider 6 comes into contact with the magnetic disk 10 and reads and writes magnetic information recorded on the magnetic disk 10. The head slider 6 has a function called DFH (Dynamic Flying High), which will be described later. The ramp 7 is a component that supports the retracted head slider 6. The magnetic disk 10 is a magnetic medium that records digital information using magnetism.

  Next, the head portion of the magnetic disk apparatus according to the first embodiment will be described with reference to FIG. FIG. 2 is a diagram for explaining the head portion of the magnetic disk apparatus according to the first embodiment. The head slider 6 according to the first embodiment is supported by the head suspension 5. The head suspension 5 is supported by the main arm 3 with the piezoelectric element 8 and the piezoelectric element 9 interposed therebetween.

  Next, the configuration of the subactuator using the piezoelectric element 8 and the piezoelectric element 9 according to the first embodiment will be described with reference to FIG. Here, FIG. 3 is a diagram illustrating the sub-actuator according to the first embodiment. The piezoelectric element 8 and the piezoelectric element 9 are installed between the head suspension 5 and the main arm 3. The piezoelectric element 8 and the piezoelectric element 9 shown in FIG. 3 undergo slip deformation (shear deformation) when a voltage in the vertical direction is applied (the upper electrode side of the piezoelectric element is deformed in the rear direction in the figure). The lower electrode side of the piezoelectric element is deformed toward the front of the figure). The magnetic disk device adjusts the minute position of the head slider 6 by deforming each piezoelectric element.

  Next, the configuration of the head slider 6 and the controller 2 included in the magnetic disk device according to the first embodiment will be described with reference to FIG. FIG. 4 is a block diagram illustrating the magnetic disk device according to the first embodiment. As shown in FIG. 4, the magnetic disk device 1 includes a controller 2, a subactuator unit 30, and a head slider 6. The subactuator unit 30 includes the piezoelectric element 8 and the piezoelectric element 9.

  The head slider 6 includes a thermal actuator 41 and a magnetic head 42. Here, the magnetic head 42 includes a reproducing element that reads magnetic information from the magnetic disk 10 and a recording element that writes magnetic information to the magnetic disk 10.

  The controller 2 includes a minute positioning controller 24, a frictional force calculation unit 21, a thermal actuator controller 22, and a position signal demodulation unit 23. The position signal demodulator 23 demodulates the position information acquired by the magnetic head 42 and transmits it to the minute positioning controller 24.

  The subactuator unit 30 includes the piezoelectric element 8 and the piezoelectric element 9. The piezoelectric element 8 and the piezoelectric element 9 are connected to a minute positioning controller 24. The piezoelectric element 8 and the piezoelectric element 9 are connected to the frictional force calculation unit 21. The frictional force calculation unit 21 is connected to the thermal actuator controller 22.

  The minute positioning controller 24 adjusts the minute position of the head slider 6 using the piezoelectric element 8 and the piezoelectric element 9 included in the subactuator unit 30. Specifically, the minute positioning controller 24 adjusts the position where the head slider 6 is in contact with the magnetic disk 10 by applying a voltage to each piezoelectric element. Further, the minute positioning controller 24 uses the position information demodulated by the position signal demodulator 23 to adjust the position where the head slider 6 is in contact with the magnetic disk 10.

  The thermal actuator controller 22 is connected to the thermal actuator 41 of the head slider 6. The thermal actuator controller 22 adjusts the strength with which the head slider 6 is in contact with the magnetic disk 10, and adjusts the frictional force generated between the head slider 6 and the magnetic disk 10. Specifically, the thermal actuator controller 22 heats the thermal actuator 41 to expand the head slider 6 and adjust the frictional force generated between the head slider 6 and the magnetic disk 10.

  The frictional force calculation unit 21 measures the frictional force generated between the head slider 6 and the magnetic disk 10 using the piezoelectric element 8 and the piezoelectric element 9 included in the subactuator unit 30. Specifically, the frictional force calculation unit 21 measures a voltage generated in the piezoelectric element 8 and the piezoelectric element 9. Each piezoelectric element generates a voltage when it is deformed by a frictional force generated between the head slider 6 and the magnetic disk 10. Therefore, the frictional force calculation unit 21 measures the frictional force generated between the head slider 6 and the magnetic disk 10 using the voltage generated in each piezoelectric element.

  Next, a method in which the magnetic disk device 1 according to the first embodiment uses the piezoelectric element 8 and the piezoelectric element 9 as subactuators will be described with reference to FIG. FIG. 5 is a diagram for explaining the subactuator of the magnetic disk device according to the first embodiment.

  In order to read magnetic information stored at high density, it is difficult to position the head slider 6 with only the voice coil motor 4. Therefore, the magnetic disk device 1 performs minute positioning of the head slider 6 using the piezoelectric element 8 and the piezoelectric element 9 as subactuators.

  As shown in FIG. 5, the magnetic disk device 1 moves the head slider 6 toward the piezoelectric element 9 when a voltage is applied so that the piezoelectric element 8 extends larger than the piezoelectric element 9. The magnetic disk device 1 moves the head slider 6 toward the piezoelectric element 8 when a voltage is applied so that the piezoelectric element 9 extends more than the piezoelectric element 8.

  The magnetic disk device 1 uses the voice coil motor 4 to slide the head slider 6 and the head suspension 5 to arbitrary positions on the magnetic disk 10. Further, the magnetic disk device 1 uses the piezoelectric element 8 and the piezoelectric element 9 to adjust the position of the head slider 6.

  Next, a method for measuring the frictional force generated between the magnetic disk 10 and the head slider 6 by the piezoelectric element 8 and the piezoelectric element 9 will be described with reference to FIGS. FIG. 6 is a diagram (1) for explaining the frictional force generated between the head slider and the magnetic disk according to the first embodiment. FIG. 7 is a diagram (2) for explaining the frictional force generated between the head slider and the magnetic disk according to the first embodiment.

  Here, as shown in FIG. 7, the frictional force F is the frictional force Fx applied in the direction in which the head suspension 5 is directed, and the direction perpendicular to Fx and the direction in which the head slider 6 moves. It is expressed separately as two components of Fy. The piezoelectric element 8 and the piezoelectric element 9 are applied with a tensile force due to the frictional force Fx and a moment due to the frictional force Fy. Therefore, a compressive force is applied to one piezoelectric element, and a tensile force is applied to the other piezoelectric element.

  Here, when the piezoelectric element 8 and the piezoelectric element 9 are deformed by applying a force from the outside, a voltage corresponding to the magnitude of the applied force is generated. Therefore, the magnetic disk device 1 according to the first embodiment measures the voltages generated in the piezoelectric element 8 and the piezoelectric element 9, and calculates the frictional force using the measured voltage. Specifically, as shown in FIG. 6, Fx can be expressed as the sum of the forces that the piezoelectric element 8 and the piezoelectric element 9 receive in the direction of the head suspension 5. Therefore, Fx can be expressed by the following equation.

On the other hand, as shown in FIG. 7, Fy represents the distances l ₁ and l ₂ from the central axis of the head suspension 5 to the piezoelectric elements 8 and 9 and the forces F ₁ and F received by the piezoelectric elements 8 and 9. ₂ and the length L of the head suspension 5 can be expressed by the following equation.

  Therefore, since the magnetic disk device 1 can calculate Fx and Fy from the forces received by the piezoelectric elements 8 and 9, the frictional force F can be calculated using the voltage generated in each piezoelectric element. .

  Next, DFH, which is a function of the head slider 6 according to the first embodiment, will be described with reference to FIG. FIG. 8 is a diagram for explaining the DFH of the head slider according to the first embodiment.

  The head slider 6 includes a reproducing element, a recording element, and a thermal actuator 41 and slides in contact with the magnetic disk 10. The thermal actuator controller 22 supplies power to the thermal actuator 41 when it is desired to increase the frictional force generated between the head slider 6 and the magnetic disk device 10.

  Then, as shown in the lower side of FIG. 8, the periphery of the thermal actuator 41 of the head slider 6 expands due to the heat generated by the thermal actuator 41. When the head slider 6 expands, it contacts the magnetic disk 10 with a stronger force. Therefore, the thermal actuator controller 22 increases the frictional force generated between the head slider 6 and the magnetic disk 10 when power is supplied to the thermal actuator 41.

  Next, the relationship between the frictional force generated between the head slider 6 and the magnetic disk, the power supplied to the thermal actuator 41, and the vibration of the head slider 6 will be described with reference to FIG. The upper graph in FIG. 9 is a graph showing the frictional force generated between the head slider 6 and the magnetic disk 10 and the electric power supplied to the thermal actuator 41. As shown in FIG. 9, the frictional force generated between the head slider 6 and the magnetic disk 10 increases according to the electric power applied to the thermal actuator 41.

  Here, the lower graph in FIG. 9 is a graph showing the vertical vibration of the head slider 6 and the electric power applied to the thermal actuator 41. Here, as shown in the lower side of FIG. 9, when the frictional force generated between the magnetic disk 10 and the head slider 6 falls within a certain range, the head slider 6 hardly generates vertical vibrations. Found that there is a range. In the range surrounded by the dotted line shown in the lower graph of FIG. 9, the head slider 6 hardly generates vertical vibrations.

  When the head slider 6 vibrates up and down, an extra load is applied to the magnetic disk 10. Further, when the head slider 6 vibrates up and down, the accuracy of reading and writing processing on the magnetic information stored in the magnetic disk 10 is lowered.

  Therefore, the magnetic disk apparatus 1 adjusts the frictional force between the head slider 6 and the magnetic disk 10 to be within the range surrounded by the dotted line shown in the upper graph of FIG. To do. Specifically, the magnetic disk device 1 uses DFH to adjust the frictional force generated between the head slider 6 and the magnetic disk 10 so as to be within the dotted line range of FIG.

  Next, a force for pressing the head slider 6 against the magnetic disk 10 using a tracking process in which the piezoelectric element 8 and the piezoelectric element 9 adjust a minute position of the head slider 6 and a frictional force measured by the piezoelectric element 8 and the piezoelectric element 9. The process for adjusting the frequency will be specifically described.

  First, a tracking process in which the magnetic disk device 1 uses the piezoelectric element 8 and the piezoelectric element 9 to adjust the position of the head slider 6 will be described. The magnetic disk 10 stores data tracks for storing information on concentric circles, and stores a position signal indicating a deviation from the data track in the vicinity of the data track.

  First, the head slider 6 reads a position signal together with magnetic information stored in the data track. The position signal demodulator 23 demodulates the position signal read by the head slider 6 and notifies the minute position controller 24 of the demodulated position signal.

  The minute positioning controller 24 recognizes the deviation between the data track and the head slider 6 based on the notified position signal, and corrects the minute deviation of the head slider 6 using the piezoelectric element 8 and the piezoelectric element 9. The micropositioning controller 24 constantly adjusts the voltage applied to the piezoelectric element 8 and the piezoelectric element 9 so that the position of the head slider 6 is maintained on the data track.

  Next, a process in which the magnetic disk device 1 uses the piezoelectric element 8 and the piezoelectric element 9 to adjust the frictional force generated between the head slider 6 and the magnetic disk 10 will be described. First, when the piezoelectric element 8 and the piezoelectric element 9 are deformed by a frictional force, a voltage is independently generated. The frictional force calculation unit 21 measures the voltage of each piezoelectric element and calculates the frictional force generated between the head slider 6 and the magnetic disk 10.

  The magnetic disk device 1 uses each piezoelectric element as a sub-actuator and a sensor for measuring frictional force. Therefore, when measuring the voltages of the piezoelectric element 8 and the piezoelectric element 9, the frictional force calculating unit 21 sums the voltage generated by the deformation of each piezoelectric element and the voltage applied by the micropositioning controller 24. Is measured as the voltage of each piezoelectric element.

  Here, when each piezoelectric element is used as a sub-actuator, the micropositioning controller 24 frequently changes the voltage applied to each piezoelectric element. On the other hand, the voltage generated by the frictional force of each piezoelectric element does not change much.

  Therefore, the frictional force calculation unit 21 measures a change in voltage of each piezoelectric element, and detects an element that changes infrequently, that is, a voltage element that changes in a low frequency range. The frictional force calculation unit 21 calculates the frictional force measured by each piezoelectric element from the voltage element that changes infrequently.

  When the frictional force generated between the head slider 6 and the magnetic disk 10 is not within an appropriate range, the frictional force calculation unit 21 controls the thermal actuator 41 included in the head slider 6 using the thermal actuator controller 22. , Adjust the friction force.

  For example, when the frictional force generated between the head slider 6 and the magnetic disk 10 is too large, the frictional force calculation unit 21 notifies the thermal actuator controller 22 that the frictional force is to be reduced.

  When the thermal actuator controller 22 receives a notification that the frictional force is to be reduced, the thermal actuator controller 22 reduces the power supplied to the thermal actuator 41 and reduces the protruding amount of the head slider 6. Then, the frictional force generated between the head slider 6 and the magnetic disk 10 decreases. Therefore, the frictional force generated between the head slider 6 and the magnetic disk 10 can be kept within an appropriate range.

  On the other hand, when the frictional force generated between the head slider 6 and the magnetic disk 10 is too small, the frictional force calculation unit 21 notifies the thermal actuator controller 22 that the frictional force is increased.

  When the thermal actuator controller 22 receives a notification to increase the frictional force, the thermal actuator controller 22 increases the power supplied to the thermal actuator 41 and increases the protrusion amount of the head slider 6. Then, the frictional force generated between the head slider 6 and the magnetic disk 10 increases. Therefore, the frictional force generated between the head slider 6 and the magnetic disk 10 can be kept within an appropriate range.

  The magnetic disk device 1 uses the piezoelectric element 8 and the piezoelectric element 9 to adjust the frictional force generated between the head slider 6 and the magnetic disk 10 and at the same time adjusts the minute position of the head slider 6. .

  Next, the flow of processing for adjusting the frictional force of the magnetic disk device 1 according to the first embodiment will be described with reference to FIG. FIG. 10 is a flowchart for explaining the flow of processing for adjusting the frictional force of the magnetic disk apparatus according to the first embodiment. First, the magnetic disk device 1 determines whether the reading and writing process has been started, triggered by the rotation speed of the magnetic disk 10 reaching a predetermined value (step S101).

  When reading and writing processing by the head slider 6 is started (Yes at Step S101), the magnetic disk device 1 calculates a frictional force generated between the head slider 6 and the magnetic disk 10 (Step S102). Next, the magnetic disk device 1 determines whether or not the calculated friction force is within a set appropriate friction force range (step S103).

  When the frictional force is not within the predetermined range (No at Step S103), the magnetic disk device 1 determines whether the frictional force is larger than the predetermined range (Step S104).

  When the frictional force is greater than the predetermined range (Yes at Step S104), the magnetic disk device 1 uses the DFH to reduce the protruding amount of the head slider 6 (Step S106). On the other hand, when the frictional force is smaller than the predetermined range (No at Step S104), the magnetic disk device 1 increases the protruding amount of the head slider 6 using DFH (Step S105).

  When the frictional force is adjusted using DFH, the magnetic disk device 1 determines whether or not the reading and writing processes are finished (step S107). If the process has not been completed (No at Step S107), the magnetic disk device 1 again calculates the frictional force generated between the head slider 6 and the magnetic disk 10 (Step S102). Further, when the process is completed (Yes at Step S107), the magnetic disk device 1 retracts the head slider 6 to the ramp 7 (Step S108) and ends the process.

  Further, when the frictional force is within the predetermined range (Yes at Step S103), the magnetic disk device 1 does not adjust the frictional force using DFH, and determines whether the reading and writing processes are completed. (Step S107).

  If the process has not been completed (No at Step S107), the magnetic disk device 1 again calculates the frictional force generated between the head slider 6 and the magnetic disk 10 (Step S102). Further, when the process is completed (Yes at Step S107), the magnetic disk device 1 retracts the head slider 6 to the ramp 7 (Step S108) and ends the process.

  Next, a flow of tracking processing according to the first embodiment will be described with reference to FIG. FIG. 11 is a flowchart for explaining the flow of the tracking process according to the first embodiment. First, the magnetic disk device 1 starts processing with the head slider 6 coming into contact with the magnetic disk 10 as a trigger.

  First, the head slider 6 determines whether or not a position signal has been acquired (step S201). Next, when the head slider 6 acquires a position signal (Yes at Step S201), the position signal demodulator 23 demodulates the position signal acquired by the head slider 6 (Step S202).

  Next, the micropositioning controller 24 uses the demodulated position signal to determine whether the head slider 6 and the data track are misaligned (step S203). If the head slider 6 and the data track are not misaligned (No at Step S203), the magnetic disk device 1 determines whether the reading and writing processes are completed (Step S205).

  When the reading and writing processes are completed (Yes at Step S205), the magnetic disk device 1 ends the tracking process. On the other hand, when the reading and writing processes are not completed (No at Step S205), the head slider 6 acquires the position signal again (Step S201).

  If the head slider 6 and the data track are misaligned (Yes at step S203), the micropositioning controller 24 executes a tracking process (step S204). When the tracking process is performed, the magnetic disk device 1 determines whether the reading and writing processes have been completed (step S205).

  When the reading and writing processes are completed (Yes at Step S205), the magnetic disk device 1 ends the tracking process. On the other hand, when the reading and writing processes are not completed (No at Step S205), the head slider 6 acquires the position signal again (Step S201).

[Effect of Example 1]
As described above, the magnetic disk device 1 according to the first embodiment uses the piezoelectric element 8 and the piezoelectric element 9 that adjust the position of the head slider 6, and the frictional force generated between the head slider 6 and the magnetic disk 10. Measure. Therefore, the magnetic disk device 1 can measure the friction force generated between the head slider 6 and the magnetic disk 10 without complicating the structure.

  In addition, the magnetic disk device 1 according to the first embodiment adjusts the strength with which the head slider 6 contacts the magnetic disk 10 according to the measured frictional force. The resulting frictional force can be adjusted.

  Therefore, the magnetic disk device 1 can keep the frictional force generated between the head slider 6 and the magnetic disk 10 within an appropriate range, and can extend the life of the head slider 6 and the magnetic disk 10. As a result, the magnetic disk device 1 can maintain a stable sliding state even with the secular change of the magnetic disk device itself.

  Although the first embodiment has been described so far, the present invention may be implemented in various different forms other than the first embodiment described above. Therefore, another embodiment included in the present embodiment will be described below as a second embodiment.

(1) Piezoelectric Element The magnetic disk device 1 according to the first embodiment has the piezoelectric element 8 and the piezoelectric element 9 between the main arm 3 and the head suspension 5 as subactuators and frictional force sensors. However, the magnetic disk device 1 of the second embodiment is not limited to this, and each piezoelectric element may be installed at another location.

  For example, as shown in FIG. 12, when the head suspension has a load beam and a flexure, each piezoelectric element may be placed between the head slider and the flexure. In the case shown in FIG. 12, each piezoelectric element is installed near the main arm between the head slider and the flexure.

  As shown in FIG. 13, in the magnetic disk device, each piezoelectric element may be installed between the head slider and the flexure on the side opposite to the main arm.

  If each piezoelectric element can be used as a sub-actuator and a friction force sensor, the magnetic disk device can measure the friction force generated between the head slider and the magnetic disk without adding new parts. Because you can reach

  Further, the magnetic disk device can more accurately measure the friction force generated between the head slider and the magnetic disk when each piezoelectric element is installed at a position in contact with the head slider.

(2) Number of Piezoelectric Elements The magnetic disk device 1 according to the first embodiment had two piezoelectric elements as a subactuator and a friction force sensor. However, the magnetic disk device according to the second embodiment is not limited to this, and may include, for example, one piezoelectric element or three or more piezoelectric elements.

  This is because the magnetic disk device can achieve its purpose if it can measure the friction force generated between the head slider and the magnetic disk by using the sub-actuator regardless of the number of piezoelectric elements.

(3) Thermal Actuator The magnetic disk device 1 according to the first embodiment adjusts the frictional force generated between the head slider 6 and the magnetic disk 10 using the thermal actuator. However, the magnetic disk device according to the second embodiment is not limited to this, and other mechanisms may be used.

  For example, the magnetic disk device may have a piezoelectric element for moving the head slider perpendicularly to the magnetic disk between the main arm and the head suspension, or at another arbitrary location. It may be. Further, the mechanism is not limited to a piezoelectric element as long as it is a mechanism for moving the head slider perpendicularly to the surface of the magnetic disk. For example, the mechanism using an electromagnetic force is used to form the head slider and the magnetic disk. You may adjust the frictional force which arises between.

  The magnetic disk drive can keep the friction force within an appropriate range when the strength of pressing the head slider against the magnetic disk is adjusted according to the measured friction force between the head slider and the magnetic disk. Because, you can reach the purpose.

(4) Operation of Subactuator The magnetic disk device 1 according to the first embodiment uses the piezoelectric element 8 and the piezoelectric element 9 to adjust the minute position of the head slider 6 and at the same time, the head slider 6 and the magnetic disk. The voltage of each piezoelectric element was measured by the frictional force generated between the two. However, the magnetic disk device according to the second embodiment is not limited to this. For example, when the minute position of the head slider 6 is not adjusted using each piezoelectric element, the voltage of each piezoelectric element is adjusted. You may measure.

  For example, the magnetic disk device may stop the tracking process when measuring the frictional force generated between the head slider 6 and the magnetic disk using each piezoelectric element.

  In addition, the magnetic disk device performs tracking processing using each piezoelectric element as a sub-actuator. Here, when the tracking process is intermittently adjusted, the magnetic disk device measures the voltage of each piezoelectric element while the tracking process is not being performed, and between the head slider and the magnetic disk. The resulting frictional force may be calculated.

(5) Friction Force and Subactuator Operation The magnetic disk device 1 according to the first embodiment uses the piezoelectric element 8 and the piezoelectric element 9 to adjust the minute position of the head slider 6. Here, the magnetic disk device according to the second embodiment may use a frictional force to adjust the minute position of the head slider 6.

  That is, the magnetic disk device calculates the frictional forces Fx and Fy using each piezoelectric element. Here, the frictional force Fy is a force generated in the direction in which the head slider moves, as shown in FIG. Therefore, the magnetic disk apparatus according to the second embodiment may adjust the position of the head slider in consideration of not only the deviation between the head slider and the data track but also the frictional force Fy.

  For example, when a frictional force Fy is generated in the direction in which the data track is stored with respect to the head slider deviated from the data track, the magnetic disk device adjusts the minute position of the head slider, The voltage applied to the piezoelectric element is lowered according to the magnitude of the frictional force Fy. This is because the frictional force Fy acts in a direction to bring the head slider closer to the data track.

  On the other hand, in the magnetic disk device, when the frictional force Fy is generated in the direction opposite to the direction in which the data track is stored with respect to the head slider that is deviated from the data track, the head slider has a minute position. In order to adjust the voltage, the voltage applied to the piezoelectric element is increased. This is because the position of the head slider is moved away from the data track by the frictional force Fy.

  The following supplementary notes are further disclosed with respect to the embodiments including the above examples.

(Supplementary Note 1) A magnetic information reading unit that contacts a magnetic storage medium and reads magnetic information recorded on the magnetic storage medium;
A position adjusting unit for adjusting a contact position of the magnetic information reading unit on the magnetic storage medium with a piezoelectric element;
A frictional force measuring unit that measures a frictional force generated between the magnetic information reading unit and the magnetic storage medium using a voltage generated in the piezoelectric element;
A magnetic disk device comprising:

(Supplementary Note 2) A friction force adjusting unit that adjusts a contact strength, which is a contact strength between the magnetic information reading unit and the magnetic storage medium, according to the friction force measured by the friction force measuring unit. The magnetic disk device according to appendix 1, further comprising:

(Additional remark 3) The said frictional force adjustment part adjusts the said contact strength so that the frequency of the vibration produced by the contact with the said magnetic information reading part and the said magnetic storage medium may become below a predetermined threshold value, It is characterized by the above-mentioned. 2. The magnetic disk device according to 2.

(Additional remark 4) The said position adjustment part stops adjustment of the said contact position, when the said frictional force measurement part is measuring the said frictional force, Any one of Additional remarks 1-3 characterized by the above-mentioned. The magnetic disk device according to 1.

(Additional remark 5) The said frictional force measurement part measures the said frictional force using the voltage which has changed in the range of a low frequency among the voltages which arose in the said piezoelectric element, The additional remarks 1-4 characterized by the above-mentioned. The magnetic disk device according to any one of the above.

(Appendix 6) The frictional force measuring unit includes a frictional force generated in a direction in which the magnetic information reading unit moves on the magnetic storage medium, and a friction generated in a direction perpendicular to the direction in which the magnetic information reading unit moves. The magnetic disk device according to any one of appendices 1 to 5, wherein force is measured individually.

(Supplementary note 7) The magnetic disk apparatus according to supplementary note 6, wherein the position adjusting unit adjusts the contact position by using the frictional force generated in a direction in which the magnetic information reading unit moves.

(Additional remark 8) The said piezoelectric element is arrange | positioned between the head suspension which supports the said magnetic information reading part, and the main arm which supports the said head suspension, Any one of Additional remark 1-7 characterized by the above-mentioned. The magnetic disk device described in 1.

(Supplementary Note 9) The piezoelectric element is disposed between the magnetic information reading unit and a flexure that supports the magnetic information reading unit, and closer to the operation center of the main arm than the magnetic information reading unit. The magnetic disk device according to any one of appendices 1 to 7, wherein

(Supplementary Note 10) The piezoelectric element is disposed between the magnetic information reading unit and a flexure that supports the magnetic information reading unit, at a position farther from the operation center of the main arm than the magnetic information reading unit. The magnetic disk device according to any one of appendices 1 to 7, wherein

(Supplementary Note 11) An acquisition step of acquiring a voltage generated in a piezoelectric element that adjusts a reading position on the magnetic storage medium of a magnetic information reading unit that reads magnetic information while being in contact with the magnetic storage medium;
A friction force measuring step for measuring a friction force generated between the magnetic information reading unit and the magnetic storage medium using the voltage acquired by the acquiring step;
A frictional force measuring method comprising:

(Supplementary Note 12) A position adjusting unit that adjusts a contact position on the magnetic storage medium of a magnetic information reading unit that reads magnetic information recorded on the magnetic storage medium while being in contact with the magnetic storage medium with a piezoelectric element;
A frictional force measuring unit that measures a frictional force generated between the magnetic information reading unit and the magnetic storage medium using a voltage generated in the piezoelectric element;
A magnetic disk control device comprising:

DESCRIPTION OF SYMBOLS 1 Magnetic disk apparatus 2 Controller 3 Main arm 4 Voice coil motor 5 Head suspension 6 Head slider 7 Lamp 8 Piezoelectric element 9 Piezoelectric element 10 Magnetic disk 21 Friction force calculation part 22 Thermal actuator controller 23 Position signal demodulation part 24 Minute positioning controller 30 Sub Actuator part 41 Thermal actuator 42 Magnetic head

Claims (7)

A magnetic information reading unit that contacts the magnetic storage medium and reads magnetic information recorded on the magnetic storage medium;
A position adjusting unit for adjusting a contact position of the magnetic information reading unit on the magnetic storage medium with a piezoelectric element;
A frictional force measuring unit that measures a frictional force generated between the magnetic information reading unit and the magnetic storage medium using a voltage generated in the piezoelectric element;
A magnetic disk device comprising:   A friction force adjusting unit that adjusts a contact strength that is a contact strength between the magnetic information reading unit and the magnetic storage medium according to the friction force measured by the friction force measuring unit; 2. The magnetic disk device according to claim 1, wherein   3. The magnetism according to claim 2, wherein the frictional force adjusting unit adjusts the contact strength so that vibration caused by contact between the magnetic information reading unit and the magnetic storage medium is a predetermined threshold value or less. Disk unit.   The said position adjustment part stops the adjustment of the said contact position, when the said frictional force measurement part is measuring the said frictional force, It is any one of Claims 1-3 characterized by the above-mentioned. Magnetic disk unit.   The frictional force measuring unit measures the frictional force using a voltage changing in a low frequency range among voltages generated in the piezoelectric element. The magnetic disk device according to one. An acquisition step of acquiring a voltage generated in a piezoelectric element that adjusts a reading position on the magnetic storage medium of a magnetic information reading unit that reads magnetic information while contacting the magnetic storage medium;
A friction force measurement method comprising: a friction force measurement step of measuring a friction force generated between the magnetic information reading unit and the magnetic storage medium using the voltage acquired in the acquisition step. A position adjusting unit that adjusts a reading position on the magnetic storage medium of a magnetic information reading unit that reads magnetic information while contacting the magnetic storage medium with a piezoelectric element;
A frictional force measuring unit that measures a frictional force generated between the magnetic information reading unit and the magnetic storage medium using a voltage generated in the piezoelectric element;
A magnetic disk control device comprising:

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