JP2010146626A - Storage device, storage device control method, and head slider - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a storage device capable of highly precisely detecting the off-track of a head, and to provide a storage device control method and a head slider. <P>SOLUTION: A plurality of read-heads are provided at a head slider. When servo information is read out from a storage medium by each read head, based on read out servo information, it is monitored whether a head is off-tracked or not, when off-track is detected, following control in which the head is follower to a target position on the storage medium is performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a storage device, a storage device control method, and a head slider.

  In general, a storage device such as a magnetic disk device reads data stored in a storage medium by a head or writes data to the storage medium. At this time, the magnetic disk device performs positioning control for on-tracking the head onto a specific track based on the servo information stored in the servo area on the storage medium. The magnetic disk device also monitors whether or not the head is off-track after turning the head on-track, and performs following control to turn the head on-track when detecting that the head is off-track. The following control is also called on-track control or track following control.

  Here, the head positioning control and following control by the conventional magnetic disk apparatus will be described with reference to FIGS. FIG. 9 is a diagram showing a configuration of a head included in a conventional magnetic disk device. As shown in FIG. 9, the conventional magnetic disk device has a read head 91 and a write head 92 on a head slider 90 connected to the arm 1. The read head 91 is a head that reads data from the magnetic storage medium, and the write head 92 is a head that writes data to the magnetic storage medium.

  FIG. 10 is a diagram for explaining a method of accessing a magnetic storage medium by a conventional magnetic disk device. In the example shown in FIG. 10, the magnetic storage medium 111 is rotationally driven by a spindle motor (not shown) (hereinafter referred to as “SPM”). The arm 1 is driven by a voice coil motor (hereinafter referred to as “VCM”) (not shown) and rotates on an arc centered on the shaft 2. The magnetic disk drive drives the arm 1 so that the read head 91 or the write head 92 provided in the head slider 90 is moved to an arbitrary track on the magnetic storage medium 111 (track T1 in the example shown in FIG. 10). To access the magnetic storage medium 111.

  FIG. 11 is a diagram for explaining the following control by the conventional magnetic disk device. In the example shown in FIG. 11, the magnetic storage medium 111 has servo areas SP11, SP12, SP13, and SP14 at predetermined intervals. Here, a case where the follow control is performed on the read head 91 will be described. The magnetic disk device monitors whether or not the read head 91 is off-track from the track T1 based on the servo information read by the read head 91.

  Specifically, when the servo information is read from the servo area SP11 by the read head 91, the magnetic disk device determines whether the read head 91 is off-track from the track T1 based on the servo information. Monitor. Thereafter, when the servo information is read from the servo area SP12 by the read head 91, the magnetic disk device monitors whether or not the read head 91 is off-track based on the servo information. Note that when the magnetic disk device detects that the read head 91 is off-track, it causes the read head 91 to be on-track on the track T1.

  As described above, the magnetic disk device performs following control for on-tracking the head based on servo information read at predetermined intervals. In FIG. 11, the example in which the follow control is performed on the read head 91 has been described. However, the same process is performed when the follow control is performed on the write head 92.

  The following control as described above is an important process in the storage device. This is because when the head is off-tracked, data cannot be read or written correctly. For example, if the read head is in an off-track state, the magnetic disk device cannot correctly read data from the magnetic storage medium. Further, for example, when the write head enters an off-track state, the magnetic disk device cannot correctly write data to the magnetic storage medium or overwrites data stored in an adjacent track.

  For these reasons, in recent years, several techniques for performing high-precision head positioning control have been proposed. For example, a technique has been proposed in which servo information is read out by a head on the back surface of a storage medium to monitor whether the head is in an on-track state when writing processing is performed by the head on the front surface of the storage medium. In addition, for example, by providing a servo track for storing servo information between data tracks for storing user data and reading the servo information with a read head dedicated to the servo track, the read head can be used while the head is on-track. Techniques for reading data have been proposed.

Japanese Patent Laid-Open No. 5-101520 JP-A-6-309824 JP 2008-217896 A

  Incidentally, in recent years, the recording capacity of storage devices has been on an increasing trend. Specifically, track density (TPI: Track Per Inch), which is the number of tracks per unit size on the storage medium, is increasing. For this reason, recent storage media tend to be in an off-track state due to a slight impact or the like because the track interval is narrow. Furthermore, since the recording density (BPI: Bit Per Inch) of the storage medium is also increasing, when the data is written in an off-track state, there is a problem that a lot of data stored in the adjacent track is overwritten.

  Under such circumstances, the above-described prior art has a problem that the off-track detection accuracy is low. Specifically, the storage device described above cannot detect the head off-track until the read head passes through a predetermined servo area and then passes through the next servo area. Since recent storage devices tend to be in an off-track state with an increase in TPI, there is a high possibility that the head will be off-track while servo information is not being read by the read head. For this reason, it has become an important issue how to realize a storage device that can detect off-track with high accuracy.

  In order to solve the above problem, it is conceivable to read the servo information with the head on the back surface of the storage medium as described above. However, this technique is based on the premise that information can be read from both sides of the storage medium, and can only be applied to a storage medium that satisfies such a precondition. It is also conceivable to narrow the interval between the servo areas arranged on the storage medium or provide the servo track as described above. However, this causes a problem of reducing the data capacity that can be written to the storage medium.

  The disclosed technique has been made in order to solve the above-described problems caused by the prior art, and provides a storage device, a storage device control method, and a head slider that can detect head off-track with high accuracy. With the goal.

  In order to solve the above-described problems and achieve the object, a storage device disclosed in the present application includes a write head that writes information to a storage medium, and a head slider that includes a plurality of read heads that read information from the storage medium; A control unit that performs following control for causing the read head or the write head to follow a target position on the storage medium based on the servo information when servo information is read by any of the plurality of read heads. It is a requirement to have.

  In addition, what applied the component, expression, or arbitrary combination of the components disclosed in the present application to a method, device, system, computer program, recording medium, data structure, etc. is also effective as another aspect. .

  According to the storage device disclosed in the present application, it is possible to detect with high accuracy whether or not the head is off-track.

  Hereinafter, embodiments of a storage device, a storage device control method, and a head slider disclosed in the present application will be described in detail based on the drawings. Note that the storage device, the storage device control method, and the head slider disclosed in the present application are not limited to the embodiment. For example, in the following embodiments, a case where the storage device disclosed in the present application is applied to a magnetic disk device will be described as an example. The storage device disclosed in the present application is a magneto-optical disk device, an optical disk device, or a memory disk device. The present invention can also be applied to a storage device such as

  First, following control by the magnetic disk device 100 according to the first embodiment will be described. The magnetic disk device 100 according to the first embodiment further includes a read head for reading servo information from the servo area in addition to the conventional read head and write head. Then, the magnetic disk device 100 performs following control based on the servo information read by the two read heads.

  The following control by the magnetic disk device 100 described above will be specifically described with reference to FIGS. FIG. 1 is a diagram illustrating a configuration of a head included in the magnetic disk device 100 according to the first embodiment. As shown in FIG. 1, the head slider 10 includes a read head 11 and a write head 12. Furthermore, the head slider 10 in the first embodiment has a read head 13 for reading servo information from the servo area.

  FIG. 2 is a diagram for explaining the following control by the magnetic disk device 100 according to the first embodiment. FIG. 2 shows the head slider 10 flying above the track T1 of the magnetic storage medium 111. First, it is assumed that the position of the head slider 10 is in the state shown in the upper part of FIG. In such a case, the read head 11 reads servo information from the servo area SP12. Then, the magnetic disk device 100 performs following control based on the servo information read by the read head 11.

  Subsequently, it is assumed that the position of the head slider 10 is in the state shown in the lower part of FIG. 2 by rotating the magnetic storage medium 111. In such a case, the read head 13 reads servo information from the servo area SP12. Then, the magnetic disk device 100 performs following control based on the servo information read by the read head 13.

  As described above, the magnetic disk device 100 according to the first embodiment performs the following control based on the servo information read by the two read heads 11 and 13, so that the frequency is twice that of the conventional magnetic disk device. Can follow control. In other words, the magnetic disk device 100 can detect whether or not the head is off-track twice as often as the conventional magnetic disk device.

  The effects of the magnetic disk device 100 described above will be described in detail by comparing the examples shown in FIGS. In the case of a conventional magnetic disk device, as shown in the example shown in FIG. 11, following control is performed based on servo information read from the servo area SP12 by the read head 91, and then read from the servo area SP13. Following control is performed based on the servo information. That is, the conventional magnetic disk device reads the servo information at intervals at which servo areas are arranged, and performs following control.

  On the other hand, the magnetic disk apparatus 100 according to the first embodiment performs the following control based on the servo information read by the read head 11 and then reads it by the read head 13 as in the example shown in FIG. Following control is performed based on the servo information. That is, the magnetic disk device 100 can perform following control based on the servo information read by the read head 13 after the read head 11 has passed through the servo area SP12 and before reaching the servo area SP13. For this reason, the magnetic disk device 100 can perform following control more frequently than a conventional magnetic disk device, and therefore can perform off-track detection processing with high accuracy.

  Note that the distance between the read head 11 and the read head 13 disposed on the head slider 10 is preferably half the interval of the servo areas. Specifically, as shown in the lower part of FIG. 2, when the interval between the servo areas is 2a, the distance between the read head 11 and the read head 13 is preferably a. As a result, the magnetic disk device 100 can read servo information at a constant interval (half the interval of the conventional magnetic disk device), and as a result, can perform following control at a constant interval.

  As described above, since the magnetic disk device 100 according to the first embodiment reads servo information by the two read heads 11 and 13, the following control can be performed with a high frequency. As a result, the head is off-tracked. It can be detected with high accuracy. If the two read heads 11 and 13 are provided on the head slider 10, the same effect as that obtained by arranging twice the servo area on the magnetic storage medium can be obtained without reducing the data capacity that can be written to the magnetic storage medium. It can be said that it is possible.

  Next, the configuration of the magnetic disk device 100 according to the first embodiment will be described. FIG. 3 is a diagram illustrating the configuration of the magnetic disk device 100 according to the first embodiment. As shown in FIG. 3, the magnetic disk device 100 includes a head slider 10, a magnetic storage medium 111, a VCM 112, an SPM 113, a head IC (Integrated Circuit) 114, a shared bus 115, a host interface (hereinafter, “ A control unit 120, a buffer control unit 130, a buffer memory 131, a format control unit 140, a read channel 150, an MPU (Micro Processing Unit) 160, a memory 170, a nonvolatile memory 180, And a servo control unit 190.

  The magnetic storage medium 111 has a magnetic film formed on a disk-shaped substrate made of metal or glass, and has a user area for storing user data, a servo area for storing servo information, and the like.

  As shown in FIG. 1, the head slider 10 has a read head 11, a write head 12, and a read head 13 for reading servo information. The read heads 11 and 13 read user data, servo information, and the like stored in the magnetic storage medium 111 while flying above the rotating magnetic storage medium 111. The write head 12 writes user data and the like to the magnetic storage medium 111 while flying above the rotating magnetic storage medium 111. Hereinafter, the read heads 11 and 13 and the write head 12 may be collectively referred to simply as “head”.

  The VCM 112 is a head driving mechanism that is driven by the servo control unit 190 and rotates the arm 1 on the magnetic storage medium 111. The SPM 113 is a mechanism that is driven by the servo control unit 190 and rotates the magnetic storage medium 111.

  The head IC 114 includes a preamplifier (not shown), and preamplifies the data signals read by the read heads 11 and 13 when reading data. The shared bus 115 connects the processing units in the magnetic disk device 100 and exchanges various information between the processing units.

  The host IF control unit 120 is connected to a host device such as a personal computer (PC) and controls communication with the host device. The buffer control unit 130 controls the buffer memory 131. The buffer memory 131 temporarily stores information exchanged between the host device and the magnetic disk device 100.

  The format control unit 140 performs an error check on data transferred between the host device and the magnetic disk device 100. For example, the format control unit 140 receives data from the read channel 150 at the time of data reading, performs error correction on the data as necessary, and outputs the data to the buffer control unit 130. For example, the format control unit 140 accepts data from the host device via the host IF control unit 120 when writing data, adds an error correction code or the like to the data, and outputs the data to the read channel 150.

  The read channel 150 AD-converts, modulates, and demodulates data transferred between the host device and the magnetic disk device 100. For example, when reading data, the read channel 150 amplifies the data signal output from the head IC 114 and performs predetermined processing such as AD conversion and demodulation. Further, for example, the read channel 150 performs code modulation on data input from the format control unit 140 when data is written.

  The MPU 160 performs main control of the magnetic disk device 100 by a firmware program. In other words, the MPU 160 decodes commands from the host device and controls each processing unit, and performs overall control of reading and writing data on the magnetic storage medium 111. The MPU 160 may be an MCU (Micro Controller Unit) or a CPU (Central Processing Unit).

  Here, the positioning control and following control by the MPU 160 will be specifically described. When the MPU 160 receives a command from the host device, the MPU 160 analyzes the command and calculates a target position on the magnetic storage medium 111 for reading or writing data. Then, the MPU 160 calculates the current position of the head based on the servo information read from the magnetic storage medium 111 by the read head 11 or 13.

  Then, the MPU 160 generates a control signal (hereinafter referred to as “VCM control signal”) for driving the VCM 112 based on the distance from the current position of the head to the target position, and uses the generated VCM control signal as a servo control unit. Output to 190. Then, when the arm 1 is rotated on the magnetic storage medium 111 by the VCM 112, the head positioning control is performed.

  The MPU 160 performs the following control after performing the positioning control on the head. Specifically, the MPU 160 calculates the current position of the head based on servo information read by the head (here, the read head 11). Then, the MPU 160 determines whether or not the head is off-track based on the current position and the target position. When it is detected that the head is off-track, the MPU 160 interrupts the data reading process or the writing process. Then, the MPU 160 generates a VCM control signal so that the positional deviation between the current position and the target position becomes zero, and outputs the generated VCM control signal to the servo control unit 190. Then, the MPU 160 resumes the data reading process or the writing process after the head is on-tracked.

  Subsequently, the MPU 160 calculates the current position of the head based on the servo information read by the read head 13. When the MPU 160 detects that the head is off-track, the MPU 160 interrupts the data reading process or the writing process, and servos the VCM control signal so that the positional deviation between the current position and the target position becomes zero. Output to the control unit 190. Then, the MPU 160 resumes the data reading process or the writing process after the head is on-tracked.

  In this way, the MPU 160 performs following control each time servo information is read by the read head 11 and the read head 13. As a result, the magnetic disk device 100 can detect with high accuracy whether or not the head is off-track.

  The memory 170 and the nonvolatile memory 180 store a predetermined control program (firmware program) operating in the MPU 160 and various control data. The servo control unit 190 drives the VCM 112 and the SPM 113 in accordance with instructions input from the MPU 160. For example, when the VCM control signal is input from the MPU 160, the servo control unit 190 drives the VCM 112 based on the VCM control signal.

  Next, processing procedures for following control by the magnetic disk device 100 according to the first embodiment will be described. FIG. 4 is a flowchart illustrating the processing procedure of the following control by the magnetic disk device 100 according to the first embodiment. Here, it is assumed that a predetermined head is in a state where positioning control is performed.

  As shown in FIG. 4, the MPU 160 of the magnetic disk device 100 according to the first embodiment reads the servo information when the servo information is read by either the read head 11 or the read head 13 (step S101). Based on this, it is determined whether or not the head is off-track.

  When it is detected that the head is off-track (Yes at Step S102), the MPU 160 interrupts the data reading process or the writing process (Step S103). Thereafter, the MPU 160 resumes the data reading process or the writing process after the head is on-tracked.

  On the other hand, when the head is not off-track (No at Step S102), the MPU 160 does not perform a process of interrupting the data reading process or the writing process.

  Subsequently, since the servo information is read by a read head different from the read head from which the servo information is read in step S101 (step S104), the MPU 160 determines whether the head is off-track based on the servo information. judge.

  When it is detected that the head is off-track (Yes at Step S105), the MPU 160 interrupts the data reading process or the writing process (Step S106). Thereafter, the MPU 160 resumes the data reading process or the writing process after the head is on-tracked.

  On the other hand, when the head is not off-track (No at Step S105), the MPU 160 returns to the processing procedure at Step S101 without performing the process of interrupting the data reading process or the writing process.

  The magnetic disk device 100 performs off-track detection processing each time servo information is read by the read head 11 or the read head 13. The magnetic disk device 100 repeats the above processing procedure even after the head has been seek-moved to another track position.

  As described above, the magnetic disk device 100 according to the first embodiment reads servo information by the two read heads 11 and 13. As a result, the magnetic disk device 100 can perform the following control with high frequency, and as a result, can detect with high accuracy whether or not the head is off-track.

  In the magnetic disk device 100 described above, even when the position of the head slider 10 is fixed at a specific position, the track position where the read head 11 floats on the magnetic storage medium 111 and the read head 13 There are cases where the position of the track that floats on the magnetic storage medium 111 is different. This is because the read head 11 and the read head 13 are arranged at different positions on the head slider 10. In the second embodiment, an example of a magnetic disk device that performs the following control in consideration of such a point that the read head 11 and the read head 13 are located on different tracks will be described.

  First, the point that the read head 11 and the read head 13 float on different tracks will be described with reference to FIG. FIG. 5 is a diagram showing the track position at which the read head 11 and the read head 13 float. In FIG. 5, it is assumed that the position of the head slider 10 is fixed. In the example shown in FIG. 5, the read head 11 is levitated on the track T3, and the read head 13 is levitated on the track T4. That is, the read head 11 and the read head 13 are levitated on different tracks. Therefore, the read head 11 reads servo information from the servo areas SP11 to SP13 formed on the track T3, and the read head 13 reads servo information from the servo areas SP11 to SP13 formed on the track T4.

  Such a difference in the track position where the read head 11 and the read head 13 float varies depending on the position of the head slider 10. This is because the head slider 10 is structured to rotate around a specific axis (axis 2 in the example shown in FIG. 10). For example, in the state shown in FIG. 5, the read heads 11 and 13 are levitated on different tracks by one, but when the head slider 10 moves to the left side in FIG. 5, the read heads 11 and 13 are There is also the possibility of floating on two or more different tracks.

  Next, the configuration of the magnetic disk device 200 according to the second embodiment will be described. FIG. 6 is a diagram illustrating the configuration of the magnetic disk device 200 according to the second embodiment. In FIG. 6, parts having the same functions as the constituent parts shown in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 6, the magnetic disk device 200 has an MPU 260 instead of the MPU 160 and a nonvolatile memory 280 instead of the nonvolatile memory 180 as compared with the magnetic disk device 100 shown in FIG. 3.

  The nonvolatile memory 280 stores a difference value between the track position of the read head 11 and the track position of the read head 13 for each position where the read head 11 floats on the magnetic storage medium 111. Such a difference value is calculated in the manufacturing process of the magnetic disk device 200. Specifically, the magnetic disk device 200 divides all tracks on the magnetic storage medium 111 into a predetermined number (for example, 40), and divides each section (hereinafter referred to as “zone (zone)”). Then, the difference in track position between the read head 11 and the read head 13 is calculated. Then, the magnetic disk device 200 stores the calculated difference value in the nonvolatile memory 280.

  Here, FIG. 7 shows an example of a difference value of the track position between the read head 11 and the read head 13. FIG. 7 shows an example in which all tracks on the magnetic storage medium 111 are divided into 40 parts. Here, it is assumed that the outermost zone of the magnetic storage medium 111 is zone “1”, and the zone adjacent to the inner side of zone “N” (N is 1 to 39) is zone “N + 1”. It shall be.

  The first line shown in FIG. 7 indicates that when the read head 11 is positioned at zone 1, the read head 13 is levitated to a track position shifted by 7.1 tracks inward from the track position of the read head 11. Show. In the last row shown in FIG. 7, when the read head 11 is positioned at the zone 40, the read head 13 is levitated at a track position shifted 6.8 tracks outward from the track position of the read head 11. It is shown that.

  The MPU 260 calculates the zone of the seek destination of the head at the time of data read processing or write processing, and acquires the difference value corresponding to the calculated zone from the nonvolatile memory 280. Then, the MPU 260 performs following control using the acquired difference value. The following control by the MPU 260 will be described in detail with reference to FIG.

  Next, a processing procedure for following control by the magnetic disk device 200 according to the second embodiment will be described. FIG. 8 is a flowchart illustrating a processing procedure of following control by the magnetic disk device 200 according to the second embodiment.

  As shown in FIG. 8, the MPU 260 of the magnetic disk device 200 calculates the seek position (target position on the magnetic storage medium 111) of the read head 11 when positioning control of a predetermined head (step S201).

  Subsequently, the MPU 260 performs a seek process for moving the read head 11 to the target position (step S202). Specifically, the MPU 260 outputs a VCM control signal to the servo control unit 190, thereby causing the VCM 112 to drive the arm 1 to perform a seek process.

  Subsequently, the MPU 260 obtains the zone to which the seek position of the read head 11 belongs. Subsequently, the MPU 260 acquires a difference value corresponding to the obtained zone from the nonvolatile memory 280 (step S203). Then, the MPU 260 calculates the track position where the read head 13 should be positioned by calculating the difference between the seek position of the read head 11 and the acquired difference value (step S204).

  Subsequently, when the servo information is read by the read head 11 (step S205), the MPU 260 determines whether the head is off-track based on the servo information.

  When it is detected that the head is off-track (Yes at Step S206), the MPU 260 interrupts the data reading process or the writing process (Step S207). Subsequently, the MPU 260 restarts the data reading process or the writing process after the head is on-tracked.

  Subsequently, when the servo information is read by the read head 13 (step S208), the MPU 260 tracks the track position indicated by the read servo information and the track on which the read head 13 calculated in step S204 is located. It is determined whether or not the position matches. Thereby, the MPU 260 determines whether or not the head is off-track.

  When it is detected that the head is off-track (Yes at Step S209), the MPU 260 interrupts the data reading process or the writing process (Step S210). Subsequently, the MPU 260 restarts the data reading process or the writing process after the head is on-tracked.

  As described above, the magnetic disk device 200 according to the second embodiment performs the following control using the difference value between the track positions of the read head 11 and the read head 13 for each zone. As a result, the magnetic disk device 200 can perform the following control even when the read head 11 and the read head 13 float on different tracks.

  Incidentally, the magnetic disk devices 100 and 200 described in the first and second embodiments may be implemented in various different forms other than the first and second embodiments described above. Therefore, in a third embodiment, another embodiment included in the magnetic disk devices 100 and 200 will be described.

[Readhead]
In the first and second embodiments, the head slider 10 has two read heads 11 and the read head 13. However, the head slider 10 may have three or more read heads. For example, when the head slider 10 has three read heads, the magnetic disk devices 100 and 200 perform following control each time servo information is read by each read head. Thus, the magnetic disk devices 100 and 200 can perform following control three times as often as the conventional magnetic disk devices.

  That is, when the head slider 10 has N read heads, the magnetic disk devices 100 and 200 can perform following control with a frequency N times that of the conventional magnetic disk device. As a result, the magnetic disk devices 100 and 200 can detect whether or not the head is off-track at a frequency N times that of the conventional magnetic disk device. If N read heads are provided on the head slider 10, the same effect as that obtained by arranging N times as many servo areas on the magnetic storage medium can be obtained without reducing the data capacity that can be written to the magnetic storage medium. It can be said.

  When N read heads are provided on the head slider 10, the interval between the read heads is preferably equal to an interval obtained by equally dividing a section of the servo area arranged in the magnetic storage medium 111 by N. Thus, the magnetic disk devices 100 and 200 can read servo information at a constant interval (1 / N interval of the conventional magnetic disk device), and as a result, follow control can be performed at a constant interval. .

[System configuration]
Each of the processing functions performed in the magnetic disk devices 100 and 200 is realized by a CPU and a program that is analyzed and executed by the CPU, or hardware by wired logic. It may be realized as.

  Each component of each illustrated device is functionally conceptual and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured.

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

(Appendix 1) A head slider having a write head for writing information to a storage medium, and a plurality of read heads for reading information from the storage medium;
A control unit that performs following control for causing the read head or the write head to follow a target position on the storage medium based on the servo information when servo information is read by any of the plurality of read heads; A storage device comprising:

(Supplementary Note 2) The plurality of read heads are arranged at an interval equal to an interval obtained by equally dividing a section of a servo area where servo information is stored in the storage medium by the number of the plurality of read heads. The storage device according to attachment 1, wherein

(Supplementary Note 3) For each position where the plurality of read heads float on the storage medium, a track position of a reference read head which is a predetermined read head among the plurality of read heads, and other than the reference read head A storage unit for storing a difference value with the track position of the read head;
The control unit acquires, from the storage unit, a difference value corresponding to a target position where the read head or the write head is levitated on the storage medium when servo information is read by the other read head. Then, the following control is performed using the obtained difference value.

(Additional remark 4) The said control part reads the track position calculated | required by the difference of the difference value acquired from the said memory | storage part, and the track position which the servo information read by the said reference read head reads by said other read head. 4. The storage device according to appendix 3, wherein the following control is performed by determining whether or not the track position indicated by the servo information is coincident.

(Supplementary Note 5) A storage device control method for controlling a storage device that reads and writes information from and to a storage medium,
The storage device is
When servo information is read by any of a plurality of read heads that read information from the storage medium, a write head that writes information to the read head or the storage medium based on the servo information is provided on the storage medium. A storage device control method comprising a control step of performing following control for following a target position.

(Appendix 6) A write head for writing information to a storage medium;
And a plurality of read heads for reading information from the storage medium.

(Supplementary note 7) The plurality of read heads are arranged at an interval equal to an interval obtained by equally dividing a section of a servo area where servo information is stored in the storage medium by the number of the plurality of read heads. The head slider according to appendix 6, which is characterized.

FIG. 3 is a diagram illustrating a configuration of a head included in the magnetic disk device according to the first embodiment. FIG. 6 is a diagram for explaining following control by the magnetic disk device according to the first embodiment. 1 is a diagram illustrating a configuration of a magnetic disk device according to a first embodiment. 4 is a flowchart illustrating a processing procedure of following control by the magnetic disk device according to the first embodiment. It is a figure which shows the track position where two read heads float. FIG. 4 is a diagram illustrating a configuration of a magnetic disk device according to a second embodiment. It is a figure which shows the example of a difference value of the track position of two read heads. 12 is a flowchart illustrating a processing procedure of following control by the magnetic disk device according to the second embodiment. It is a figure which shows the structure of the head which the conventional magnetic disc device has. It is a figure for demonstrating the access method to the magnetic storage medium by the conventional magnetic disc apparatus. It is a figure for demonstrating following control by the conventional magnetic disc unit.

Explanation of symbols

1 Arm 2 Axis 10, 90 Head Slider 11, 13 Read Head 12 Write Head 91 Read Head 92 Write Head 100, 200 Magnetic Disk Device 111 Magnetic Storage Medium 112 VCM
113 SPM
114 head IC
115 Shared Bus 120 Host IF Control Unit 130 Buffer Control Unit 131 Buffer Memory 140 Format Control Unit 150 Read Channel 160, 260 MPU
170 Memory 180, 280 Nonvolatile memory 190 Servo controller

Claims (6)

A head slider having a write head for writing information to a storage medium, and a plurality of read heads for reading information from the storage medium;
A control unit that performs following control for causing the read head or the write head to follow a target position on the storage medium based on the servo information when servo information is read by any of the plurality of read heads; A storage device comprising:   In the head slider, the plurality of read heads are arranged at an interval equal to an interval obtained by equally dividing a section of a servo area where servo information is stored in the storage medium by the number of the plurality of read heads. The storage device according to claim 1. A track position of a reference read head that is a predetermined read head among the plurality of read heads and a track of a read head other than the reference read head for each position where the plurality of read heads float on the storage medium. A storage unit for storing a difference value from the position;
When the servo information is read by the other read head, the control unit acquires, from the storage unit, a difference value corresponding to a target position where the read head or the write head is levitated on the storage medium. The storage device according to claim 1, wherein the following control is performed using the obtained difference value. A storage device control method for controlling a storage device that reads and writes information from and to a storage medium,
The storage device is
When servo information is read by any of a plurality of read heads that read information from the storage medium, a write head that writes information to the read head or the storage medium based on the servo information is provided on the storage medium. A storage device control method comprising a control step of performing following control for following a target position. A write head for writing information to a storage medium;
And a plurality of read heads for reading information from the storage medium.   The plurality of read heads are arranged at an interval equal to an interval obtained by equally dividing a section of a servo area in which servo information is stored in the storage medium by the number of the plurality of read heads. Item 6. The head slider according to Item 5.

Images