JP2011123952A - Magnetic disk device which applies correction information in accessing data track - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently access a data track which is inefficiently accessed when in normal use. <P>SOLUTION: A CPU 22 detects whether a predetermined criterion is satisfied or not by accessing a data track available on a disk 11 in an HDD 10. The CPU 22 obtains correction information for use in the predetermined criterion when the predetermined data track does not satisfy the criterion. The CPU 22 stores the obtained correction information in association with the predetermined data track, in an area 231 of an FROM 23. The CPU 22 controls access to the predetermined data track based on the correction information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic disk device that applies correction information when accessing a data track, and can use correction information suitable for the data track, particularly when accessing a data track with poor access efficiency in a normal usage mode. The present invention relates to a magnetic disk device.

  In general, in a magnetic disk device, head positioning control for positioning a head on a target data track (target track) is performed. The head positioning control includes seek control for moving the head to the target track and track following control for setting the head moved to the target track to the target position of the target track. The head positioning control may refer to track following control in a narrow sense.

  In the head positioning control, a deviation (that is, an error) from the target position that occurs when the head is positioned on the target track is called a position error. For example, Patent Documents 1 and 2 disclose various factors of this position error. Patent Documents 1 and 2 disclose that an eccentricity occurs in a track on a disk due to a factor associated with the rotation of the disk, for example. Further, Patent Documents 1 and 2 disclose, as factors associated with the rotation of the disk, shaft vibration of the spindle motor for rotating the disk, vibration of the disk when servo information is written to the disk, expansion and contraction of the disk shape, and the like. ing.

  In particular, Patent Document 1 discloses a technique (hereinafter, referred to as a prior art) for suppressing a position error (that is, an eccentric component) caused by the eccentricity of a track that occurs as a disk rotates based on correction information acquired by learning. ) Along with the theory.

  On the other hand, Patent Document 2 discloses a technique for shortening the time required to detect a synchronization component having a correlation between a plurality of tracks by learning processing, together with theory. The learning process described in this Patent Document 2 is performed based on a synchronization component (that is, an eccentric component) of a track synchronized with the rotation of the disk.

JP 11-39814 A JP 2000-195202 A

  In the above prior art, the correction information used to suppress the position error due to the eccentricity of the track is optimized by learning for each of a plurality of areas (more specifically, ring-shaped areas) on the disk. To be acquired. Each of the plurality of areas has a plurality of tracks. Correction information (hereinafter referred to as area learning value) acquired for each area is stored in a memory.

  According to the above prior art, in the positioning control for positioning the head on the target track, the area learning value corresponding to the area to which the target track belongs can be read from the memory and used.

  However, if the degree of correlation between the target track and other tracks in the area to which the target track belongs is relatively low with respect to the eccentric component (for example, the synchronous component as described in Patent Document 2), Invite such a state. In the following description, a track having a relatively low degree of correlation with respect to an eccentric component with another track (for example, an adjacent track) is referred to as a first type track. A track having a high degree of correlation with respect to an eccentric component with another track is referred to as a second type track.

  First, correction information for suppressing the eccentric component of the first type track (that is, the learning value of the first type track) is an area learning value corresponding to the area to which the first type track belongs. With different values. Therefore, if the head positioning control for positioning the head on the first type track is performed based on the area learning value, the head positioning accuracy deteriorates, the seek response time deteriorates, and the convergence speed of the correction information learning deteriorates. appear.

  Usually, since the degree of correlation with respect to the eccentric component is extremely low with other tracks in the area, a track that does not satisfy a predetermined criterion (first criterion) (that is, use in the criterion) The difficult track) is detected as a defective track in the process (manufacturing process) of manufacturing the corresponding magnetic disk device. The track detected as a defective track is, for example, a track that cannot write data or a track that cannot read data. An alternative track is assigned to the detected defective track.

  On the other hand, since the eccentric component of the first type track described above is relatively low with respect to the degree of correlation with other tracks, the first type track satisfies the determination criterion. For this reason, the first type track is not detected as a defective sector in the manufacturing process. This is because the first type of track that satisfies the above-mentioned criteria can write or read data, although it takes a long time to write or read data. Therefore, the first type of truck passes inspection in the manufacturing process.

  When an access to the first type track that has passed the inspection occurs, as described above, the head positioning accuracy deteriorates, the seek response time deteriorates, and the correction information learning convergence speed deteriorates. That is, the first type of track has poor access efficiency. Also, after shipment of the magnetic disk device, the second type track may change to the first type track due to, for example, a change with time.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a magnetic disk device capable of efficiently accessing a data track that has poor access efficiency in a normal usage mode.

  According to one aspect of the present invention, a magnetic disk device is provided. The magnetic disk device includes a storage unit, a detection unit that accesses an available data track on the disk in the magnetic disk device and detects whether a predetermined criterion is satisfied, and the predetermined data track includes the predetermined data track. Correction information acquisition means for acquiring correction information for use in the predetermined determination criterion when the determination criterion is not satisfied, and the acquired correction information in association with the predetermined data track, the storage Storage means for storing in the means, and control means for controlling access to the predetermined data track based on the correction information.

  According to the present invention, for example, even an available data track that has passed the inspection in the manufacturing process of the magnetic disk device is used according to the predetermined determination criterion when the predetermined determination criterion is not satisfied. Correction information is acquired and stored in a storage unit in association with a data track that does not satisfy the predetermined determination criterion, so that the correction information is used to obtain a data track that does not satisfy the predetermined determination criterion. Can control access. Therefore, according to the present invention, it is possible to efficiently access a data track that does not satisfy a predetermined criterion.

1 is a block diagram showing a configuration of an electronic apparatus including a magnetic disk device according to an embodiment of the present invention. The conceptual diagram which shows the example of the zone arrangement | positioning on the disk applied in the embodiment. The figure which shows the example of the track shape reflecting the eccentricity of the some track | truck in the same area. 6 is a flowchart showing a procedure of head positioning processing in the embodiment. 6 is a flowchart showing a procedure of correction information determination processing included in the head positioning processing. The figure which shows the example of the relationship between the area learning value with respect to the sector position on a track | truck in the same embodiment, and a track learning value, respectively when the difference of an area learning value and a track learning value is small and large. The figure which shows the value which integrated the difference of an area learning value and a track learning value with a bar graph about each when the difference of the area learning value and track learning value in the example of FIG. 6 is small and large.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an electronic apparatus 1 including a magnetic disk device according to an embodiment of the present invention. The electronic device 1 includes a magnetic disk device (HDD) 10 and a host 100. The electronic device 1 is, for example, a personal computer, a video camera, a music player, a mobile terminal, or a mobile phone. The host 100 uses the HDD 10 as a storage device of the host 100. The HDD 10 is connected to the host 100 by a host interface 110.

  The HDD 10 includes a disk (magnetic disk) 11 as a recording medium. The disk 11 has two upper and lower disk surfaces. For example, the upper disk surface of the disk 11 forms a recording surface on which data is magnetically recorded. A head (magnetic head) 12 is disposed corresponding to the recording surface of the disk 11. The head 12 is used for data writing to the disk 11 and data reading from the disk 11. 1 shows an example of the HDD 10 having one head 12 for the sake of drawing. However, in general, the two disk surfaces of the disk 11 together form a recording surface, and a head is disposed corresponding to each disk surface. In the configuration of FIG. 1, the HDD 10 including a single disk 11 is assumed. However, it may be an HDD in which a plurality of disks 11 are stacked.

  The disk 11 is rotated at high speed by a spindle motor (SPM) 13. The head 12 is attached to the tip of the actuator 14. The head 12 floats on the disk 11 as the disk 11 rotates at a high speed. The actuator 14 has a voice coil motor (VCM) 15 serving as a drive source for the actuator 14. The actuator 14 is driven by the VCM 15 to move the head 12 in the radial direction of the disk 11. That is, the actuator 14 supports the head 12 so as to be movable in the radial direction of the disk 11. The head 12 is positioned on the target track of the disk 11 by the operation of the actuator 14. The SPM 13 and the VCM 15 are driven by drive currents respectively supplied from the motor driver IC 16.

  On the recording surface of the disk 11, a plurality of servo areas 111 are discretely arranged radially in the radial direction of the disk 11 and at equal intervals in the circumferential direction of the disk 11. Servo data is magnetically written in advance in each servo area 111. FIG. 1 shows a case where the number of servo areas 111 is 12 for the sake of drawing. However, the number of servo areas 111 is generally 100 or more in recent HDDs.

  The servo data includes position information used for control (head positioning control) for positioning the head 12 at the target radial position of the disk 11 with respect to the disk 11 rotated by the SPM 13. This position information includes a cylinder code (cylinder number) and burst data. The cylinder code indicates a cylinder (track) position on the disk 1-i in which corresponding servo information is written. The burst data indicates relative position information (position error) of the head in the cylinder in which the corresponding servo data is written. By the head positioning control based on the servo data, the head 12 can move along the target concentric circle 112 on the recording surface of the disk 11 (that is, follow the concentric circle 112). However, the concentric circle 112 is generally eccentric with respect to the center of the disk 11.

  In the disk 11, an area sandwiched between adjacent servo areas on the concentric circle 112 is called a user data area 113. In the user data area 113, a plurality of data sectors (hereinafter simply referred to as sectors) are arranged. The head 12 writes data to the user data area 113 on the concentric circle 112 or reads data from the area on the concentric circle 112 while following the concentric circle 112. An area on the concentric circle 112 on the recording surface of the disk 11 is called a track. Therefore, in the following description, this track is expressed as a track 112.

  A recording format called CDR (constant density recording) is applied to the disk 11. The recording surface of the disk 11 to which this CDR format is applied is managed by being divided into a plurality of zones (CDR zones) in the radial direction of the disk 11. The number of sectors per track (cylinder) in each zone is set to be larger in the zone on the outer peripheral side of the disk 11.

  FIG. 2 is a conceptual diagram showing an example of zone arrangement on the disk 11. In the example of FIG. 2, for the sake of simplicity, the recording surface of the disk 11 is managed by being divided into three zones Z0 to Z2, and each zone Zi (i = 0, 1, 2) is composed of two tracks. Shall be. Actually, the recording surface of the disk 11 is divided into more than three zones, and each zone is composed of more than two tracks. In the example of FIG. 2, the servo area 111 shown in FIG. 1 is omitted.

  A lamp 17 is disposed at a position off the recording surface of the disk 11, for example, a position close to the outer periphery of the disk 11. The lamp 17 provides a retreat area 171 for retracting the head 12 while the HDD 10 is in a non-operating state. Note that the non-operating state includes a state of a specific power save mode of the HDD 10 in addition to a state in which the HDD 10 has completely stopped its operation as when the power of the HDD 10 is shut off. The specific power save mode is set not only autonomously in the HDD 10 but also by an instruction from the host 100.

  The head 12 is connected to a head IC (head amplifier circuit) 18 through a wiring pattern formed on a flexible printed cable (FPC) (not shown). The head IC 18 includes a read amplifier that amplifies the read signal read by the head 12 and a write driver (none of which is shown) that converts write data into a write current.

  The head IC 18 is connected to a read / write IC (read / write channel) 19. The read / write IC 19 is a signal processing module that executes various types of signal processing. The read / write IC 19 executes an analog / digital conversion process for converting the read signal amplified by the head IC 18 into digital data. The read / write IC 19 executes a process for extracting servo data from the digital data. The read / write IC 19 executes a process for decoding the digital data (read data) and a process for encoding the write data.

  The read / write IC 19 is connected to a disk controller (HDC) 20 and a CPU 21. The HDC 20 is connected to the buffer RAM 21 and the CPU 22. The HDC 20 is also connected to the host 100 via the host interface 110. The HDC 20 has a host interface control function that controls reception of commands (write command, read command, etc.) transferred from the host 100 via the host interface 110 and data transfer between the host 100 and the HDC 20. The HDC 20 also has a disk interface control function for controlling data transfer between the disk 11 and the HDC 20 performed via the read / write IC 19. The HDC 20 also has a buffer interface control function for controlling the buffer RAM 21.

  A part of the storage area of the buffer RAM 21 is used as a write buffer for temporarily storing data (write data) to be written to the disk 11 via the HDC 20. Another part of the storage area of the buffer RAM 21 is used as a read buffer for temporarily storing data (read data) read from the disk 11 via the HDC 20.

  The CPU 22 is connected to the motor driver IC 16 and to a flash ROM (FROM) 23 and a RAM 24. The FROM 23 is a rewritable nonvolatile memory that stores a control program (firmware) to be executed by the CPU 22. The RAM 24 is a volatile memory that provides a work area for the CPU 22. The CPU 22 functions as a main controller of the HDD 10 by executing a control program. The control program includes a head positioning process routine.

  A part of the storage area of the FROM 23 is assigned to the first learning value area 231, and another part of the storage area of the FROM 23 is assigned to the second learning value area 232. The second learning value area 232 is a well-known learning value (that is, an area learning value) acquired for each predetermined area (more specifically, a ring-shaped area) on the disk 11 at the manufacturing stage of the HDD 10. , Used as second storage means (storage module) for storing in association with the area (more specifically, information for specifying the area). The area learning value stored in the second learning value area 232 is updated as necessary. This update condition will be described later.

  In the present embodiment, the predetermined area is a zone. Therefore, the area may be read as a zone. Note that when the two disk surfaces of the disk 11 are both recording surfaces and a head is arranged corresponding to each disk surface, the area learning value is the area (more specifically, the area is specified). Information) and a head existing on the recording surface side to which the area belongs (more specifically, information for specifying the head) and stored in the second learning value area 232. In the present embodiment in which the area is a zone, the information for specifying the area is, for example, a zone number, and the information for specifying the head is, for example, a head number.

  The first learning value area 231 stores a learning value (track learning value) of a track acquired after the HDD 10 is shipped in association with the track (more specifically, information for specifying the track). Used as first storage means (storage module). The track learning value stored in the first learning value area 231 is updated as necessary. The information for specifying the track is, for example, a track number. Unlike the present embodiment, the track number is determined from the head number and the cylinder number when there are a plurality of heads. Conditions for storing or updating the track learning value will be described later.

  FIG. 3 shows five tracks N−2, N−1, N, N + 1, track numbers N−2, N−1, N, N + 1, N + 2 belonging to the same zone (area) Zi on the disk 11. An eccentric state with respect to the center of the N + 2 disk 11 is schematically shown as a track shape. Here, the eccentricity occurs with the rotation of the disk 11 (more specifically, in synchronization with the rotation of the disk 11). In FIG. 3, a broken line shows an ideal track shape when there is no eccentricity of the tracks N−2, N−1, N, N + 1, and N + 2.

  In the example of FIG. 3, it is assumed that the degree of correlation between the tracks N−2, N−1, N, and N + 2 is high with respect to the eccentric component, for example, the eccentric component synchronized with the rotation of the disk 11 (that is, the synchronous component). On the other hand, the track N + 1 has a relatively low degree of correlation with the other tracks N-2, N-1, N, N + 2 (especially adjacent tracks N, N + 2) with respect to the eccentric component. Track N + 1 is referred to as an adjacent uncorrelated track or a first type of track. Tracks N-2, N-1, N, and N + 2 are referred to as adjacent correlation tracks or second type tracks.

  Next, the operation of the present embodiment will be described with reference to the flowcharts of FIGS. 4 and 5, taking as an example a head positioning process for positioning the head 12 on a target track (target track) 112 on the disk 11. . Here, it is assumed that the target track 112 belongs to the zone Zi.

  The CPU 22 refers to the first learning value area 231 of the FROM 23 when positioning the head 12 on the target track 112. The CPU 22 functions as a determination (detection) unit, and determines whether the learning value (track learning value) of the target track 112 is stored in the first learning value area 231 in association with the track number of the target track 112. (Step 401).

  If the learning value of the target track 112 is stored in the first learning value area 231 (YES in step 401), the CPU 22 proceeds to step 402. In step 402, the CPU 22 functions as a selection unit, and selectively acquires the learning value of the target track 112 from the first learning value area 231. The acquired learning value of the target track 112 is used as correction information (first correction information) for suppressing an eccentric component synchronized with the rotation of the disk 11 of the target track 112.

  On the other hand, when the learning value of the target track 112 is not stored in the first learning value area 231 (NO in step 401), the CPU 22 proceeds to step 403. In step 403, the CPU 22 functions as a selection unit, and the learning value of the zone (area) Zi associated with the zone number of the zone (area) Zi to which the target track 112 belongs is stored in the second learning value area 232 of the FROM 23. Get selectively from. The acquired learning value of the area Zi is used as correction information (second correction information) for suppressing an eccentric component synchronized with the rotation of the disk 11 of the target track 112 belonging to the area Zi.

  When the CPU 22 acquires the correction information in step 402 or 403, the CPU 22 functions as a head positioning control means and executes head positioning control (step 404). In this head positioning control, seek control and track following control are performed.

  The seek control is executed in order to move the head 12 to the target track 112 on the disk 11 as is well known. In the seek control, the CPU 22 calculates a control value indicating a drive current necessary for moving the head 12 from the current position to the target track 112. The CPU 21 sets this control value in the VCM driver in the motor driver IC 16. The VCM driver supplies the drive current represented by the set control value to the VCM 15 to drive the VCM 15 and rotate the actuator 14. As a result, the head 12 moves on the disk 11 in the radial direction of the disk 11.

  At this time, the head 12 reads information magnetically recorded on the disk 11 and outputs it as a read signal. The head IC 18 amplifies this read signal. The read / write IC 19 converts the amplified read signal into digital data, and extracts servo data from the digital data. The CPU 22 determines the current position of the head 12 (more specifically, the radial position on the disk 11) based on the servo data extracted by the read / write IC 19 (more specifically, the cylinder code included in the servo data). ) Is detected. The CPU 22 again generates a control value necessary for moving the head 12 to the target track 112 from the detected position of the current head 12 by calculation. Thereafter, similarly, seek control for moving the head 12 to the target track 112 is performed.

  As is well known, the track following control is executed in order to set the head 12 moved to the target track 111 to the target position of the target track 111. In the track following control, the CPU 22 detects the deviation of the current position of the head 12 from the target position based on the servo data extracted by the read / write IC 19 (more specifically, burst data included in the servo data). Detect as position error.

  The CPU 22 calculates a first control value for setting (positioning) the head 12 at the target position of the target track 112 in accordance with the detected position error. The CPU 22 also calculates a second control value for removing the eccentric component (that is, the learned value of the eccentric component) indicated by the correction information from the detected position error based on the acquired correction information.

  The CPU 22 calculates a corrected control value for setting the head 12 at the target position of the target track 112 by adding the first control value and the second control value. The CPU 22 sets the calculated control value in the VCM driver in the motor driver IC 16 to set the head 12 at the target position. Then, the CPU 22 detects the position error again. This position error represents the result of one track following control (that is, feedback control for track following).

  The CPU 22 determines whether this position error is less than a predetermined first threshold TH1 (step 405). If the position error is less than the first threshold value TH1 (YES in step 405), the CPU 22 determines that the head 12 has been set to the target position of the target track 112. In this case, the CPU 22 controls a write / read operation for writing data to the target track 112 (more specifically, a target sector of the target track 112) or reading data from the target track 112 (step 406). . Then, the CPU 22 determines whether or not the next write / read operation should be executed (step 407). If so (YES in step 407), the CPU 22 returns to step 401, otherwise (in step 407). NO), the head positioning process is terminated.

  On the other hand, if the position error is not less than the first threshold value TH1 (NO in step 405), the CPU 22 determines that the head 12 could not be set at the target position of the target track 112. That is, the CPU 22 functions as a correction information acquisition unit and determines that the head positioning has not converged. In this case, the CPU 22 learns the correction information of the target track 112 by a learning type feedforward control system as described in Patent Document 1 or 2 (step 408). That is, the CPU 22 detects (learns) an eccentric component of the target track 112, for example, an eccentric component (synchronous component) synchronized with the rotation of the disk 11, and uses the detected eccentric component as correction information (that is, a learning value) of the target track 112. ) Get as.

  Next, the CPU 22 functions as a determination (detection) unit, and determines whether or not the learning value of the target track 112 acquired in step 408 is significantly different from the learning value of the area Zi to which the target track 112 belongs. The CPU 22 uses a determination value and a predetermined second threshold TH2 for this determination. For example, the CPU 22 uses the integrated value ΣΔ of the difference Δ between the learned value of the area Zi and the acquired learned value of the target track 112 as the determination value. That is, the CPU 22 determines whether the learning value of the target track 112 is not significantly different from the learning value of the area Zi by determining whether the determination value is less than the second threshold value TH2 (step 409).

  Hereinafter, the significance of this determination will be described with reference to FIGS. 6A and 6B show an example of the relationship between the area learning value and the track learning value (Y-axis direction) with respect to the sector position on the track (X-axis direction) and the area learning value. Each of the cases where the difference from the track learning value is small and large is schematically shown. The difference is represented by ΔA in FIG. 6A and represented by ΔB in FIG. 6B. That is, in FIGS. 6A and 6B, the length in the Y-axis direction of the area (hatched area) surrounded by the curves indicating the area learning value and the track learning value is the area learning value and the track learning. It corresponds to the difference with the value.

  The CPU 22 calculates an integrated value Δ of the difference between the area learning value and the track learning value in the determination at step 409. Then, the CPU 22 uses the integrated value Δ as a determination value to determine whether the determination value (integrated value Δ) is less than the second threshold value TH2 (step 409). For example, the second threshold value TH2 is experimentally determined so that the head positioning accuracy when the head 12 is positioned at the target position of the target track and the operation performance of the HDD 10 satisfy the HDD specifications. Note that the second threshold TH2 is not necessarily a fixed value. For example, the second threshold TH2 may be switched according to conditions such as the area (zone) to which the target track 112 belongs, or the operating environment (temperature, pressure) of the HDD 10.

  FIG. 7 shows values (integrated values) DVA (= ΣΔA) and DVB (= ΣΔB) obtained by integrating the differences ΔA and ΔB between the area learning value and the track learning value shown in FIGS. Shown as a bar graph. In the example of FIG. 7, the integrated value DVA (= ΣΔA) is less than the second threshold value TH2, and the integrated value DVB (= ΣΔB) exceeds the second threshold value TH2.

  When the integrated value (that is, the determination value) of the difference between the area learning value and the track learning value is less than the second threshold value TH2 (YES in step 409), as in the integrated value DVA shown in FIG. It is determined that the area learning value is equal to the track learning value. In this case, the CPU 22 proceeds to step 410.

  The area learning value and the track learning value are equal to each other. The degree of correlation regarding the eccentric component synchronized with the rotation of the disk 11 between the target track 112 and other tracks in the area Zi is determined in advance. Means higher than the threshold (correlation degree). That is, the area learning value and the track learning value are equal to each other with respect to the eccentric component synchronized with the rotation of the disk 11 between the target track 112 and other tracks in the area Zi. Means a second type of track (adjacent correlation track).

  When the target track 112 is the second type of track, even if the head positioning control for positioning the head 12 on the target track 112 based on the area learning value is executed, there is no possibility that the access efficiency is deteriorated. That is, the target track 112 that is determined to be the second type of track with the second threshold TH2 as a determination criterion can be used based on the area learning value (second correction information). This is equivalent to the fact that the target track 112 that is determined to be the second type of track can be used based on the determination criterion (second determination criterion). This criterion (second criterion) is equivalent to or relatively higher than the criterion (first criterion) used for the inspection in the manufacturing process.

  On the other hand, when the integrated value (that is, the determination value) of the difference between the area learning value and the track learning value exceeds the second threshold value TH2 as in the integrated value DVB shown in FIG. 7 (NO in step 409) ), The CPU 22 determines that the area learning value and the track learning value are not equal (different). In this case, the CPU 22 proceeds to step 411.

  If the area learning value and the track learning value are not equal, the degree of correlation regarding the eccentric component synchronized with the rotation of the disk 11 between the target track 112 and other tracks in the area Zi is a predetermined threshold value. It means lower than (correlation degree). That is, if the area learning value and the track learning value are not equal, there is no correlation between the target track 112 and the other tracks in the area Zi with respect to the eccentric component synchronized with the rotation of the disk 11, and the target track 112 It means a first type of track.

  When the target track 112 is the first type of track, if the head positioning control for positioning the head 12 on the target track 112 based on the area learning value is executed, the access efficiency may be deteriorated. That is, it is difficult to use the target track 112 that is determined to be the first type of track with the second threshold TH2 as a determination criterion based on the area learning value (second correction information).

  As the determination value, a parameter other than the integrated value of the difference between the area learning value and the track learning value can be used. For example, assuming that the time required to acquire the area learning value and the track learning value is Te and Tt, the disc 11 is inserted between the times Te and Tt, the difference in the number of retries that occurred between the times Te and Tt. It is also possible to use the difference in the number of rotations or the difference between the times Te and Tt.

  Now, since it is determined that the area learning value is equal to the track learning value, the CPU 22 proceeds to step 410. In this step 410, the CPU 22 functions as correction information acquisition means, and learns correction information of the area Zi to which the target track 112 belongs, for example, by a learning type feedforward control system as described in Patent Document 1. That is, the CPU 22 detects (learns) an eccentric component having a correlation between tracks in the area Zi, for example, an eccentric component (synchronous component) synchronized with the rotation of the disk 11, and corrects the detected eccentric component in the area Zi. Obtained as information (that is, learned value). In step 410, the CPU 22 further functions as a storage unit, and the correction information (learned value) stored in the second learning value area 232 of the FROM 23 corresponding to the area Zi is used as the acquired correction information of the area Zi. Update.

  Next, the CPU 22 returns to step 404 and executes head positioning control again. The CPU 22 uses the correction information of the area Zi corrected in step 410 for the head following control in the head positioning control.

  Next, since it is determined that the area learning value is different from the track learning value, the CPU 22 proceeds to step 411. In step 411, the CPU 22 executes a process (correction information determination process) for determining correction information used for head tracking control in the head positioning control in step 404.

Hereinafter, the correction information determination process will be described with reference to the flowchart of FIG.
First, the CPU 22 functions as a determination (detection) unit, and in the same manner as in the step 401, the learning value of the target track 112 (hereinafter referred to as the learning value LVo) is associated with the track number of the target track 112 and the first value of the FROM 23 is stored. It is determined whether it is stored in one learning value area 231 (step 501). If the learning value LVo of the target track 112 is stored in the first learning value area 231 (YES in step 501), the CPU 22 proceeds to step 502.

  In step 502, the CPU 22 learns the learning value LVo of the target track 112 stored in the first learning value area 231 and the learning value of the target track 112 newly acquired in the step 408 (hereinafter referred to as learning value LVn). ) Is equivalent. The CPU 22 uses a determination value and a predetermined third threshold TH3 for this determination. As this determination value, the CPU 22 uses, for example, an integrated value of a difference between the learning value LVo of the target track 112 stored in the first learning value area 231 and the newly acquired learning value LVn of the target track 112. Use. That is, the CPU 22 determines whether the learning values LVo and Ln are equal by determining whether the determination value (the integrated value of the differences) is less than the third threshold value TH2 (step 502).

  When the learning values LVo and Ln are equal (YES in step 502), the CPU 22 proceeds to step 503. In step 503, the CPU 22 discards the learning value Ln, that is, the newly acquired learning value of the target track 112. Thereby, it is possible to prevent the learning value of the target track 112 stored in the first learning value area 231 of the FROM 23 from being updated unnecessarily.

  Next, the CPU 22 functions as correction information determination means, and uses the learning value LVo, that is, the learning value of the target track 112 stored in the first learning value area 231 for head tracking control in head positioning control in step 404. The correction information to be determined is determined (step 504). Thus, the correction information determination process (step 411) is completed.

  Then, the CPU 22 returns to step 404 and executes head positioning control again. The CPU 22 uses the target track 112 stored in the first learning value area 231 (that is, step 504 in the correction information determination process) determined in the correction information determination process (here, step 504 in the correction information determination process) for the head follow-up control in the head positioning control. First type track) correction information is used.

  On the other hand, if the learned values LVo and Ln are not equal (NO in step 502), the CPU 22 proceeds to step 505. In step 505, the CPU 22 functions as a storage unit, and associates the learning value Ln, that is, the newly acquired learning value of the target track 112 with the track number of the target track 112 in the first learning value area 231 of the FROM 23. Store. In step 505, the learning value Lo already stored in the first learning value area 231 is updated to the learning value Ln. Even when the learning value of the target track 112 is not stored in the first learning value area 231 (NO in step 501), the CPU 22 proceeds to step 505. In this step 505, the CPU 22 newly stores the learning value Ln in the first learning value area 231.

  In order to newly store the learning value Ln in the first learning value area 231, there must be an empty space in the first learning value area 231. If there is no free space, it is necessary to secure a free space in the first learning value area 231. Therefore, the CPU 22 applies the following method in order to secure an empty space in the first learning value area 231. That is, the CPU 22 assigns an alternative track on the disk 11 to a track associated with a learning value (track learning value) already stored in the first learning value area 231. Then, the CPU 22 erases the learning value stored in the first learning value area 231 in association with the track to which the alternative track is assigned. Here, as a method of selecting a track to which an alternative track is assigned, a first-in first-out method according to the order in which corresponding learning values are stored in the first learning value area 231 or a method of sequentially selecting from a track with low access frequency can be applied. It is.

  When the CPU 22 executes step 505, it functions as correction information determination means, and uses the learning value LVn, that is, the newly acquired learning value of the target track 112, for correction information used for head tracking control in head positioning control in step 404. (Step 506). Thus, the correction information determination process (step 411) is completed.

  Then, the CPU 22 returns to step 404 and executes head positioning control again. The CPU 22 performs the head follow-up control in the head positioning control in the newly acquired target track 112 (that is, the first type track) determined in the correction information determination process (here, step 506 in the correction information determination process). ) Correction information is used.

  Now, it is assumed that the newly acquired correction information (learning value) of the first type track is stored in the first learning value area 231 of the FROM 23, and the head positioning process according to the flowchart of FIG. Thereafter, it is assumed that the head positioning process is started again with the first type of track as the target track 112. In this case, the correction information of the first type track is already stored in the first learning value area 231 of the FROM 23 (YES in Step 401). Therefore, head positioning control for positioning the head 12 on the track 112 is executed using the correction information of the first type track as the learning value of the target track 112 (steps 402 and 404). In this head positioning control, the eccentric component due to the eccentricity of the target track 112 having a low correlation with other tracks is suppressed based on the correction information of the first type track. This is equivalent to the fact that the target track 112 that is determined to be the first type of track can be used based on the determination criterion (second determination criterion).

  According to the present embodiment, the learning values of the first type track that has passed the inspection in the manufacturing process are stored in the first learning value area 231 of the FROM 23 and can be used, so that they are listed below. Effects can be obtained.

  1) The positioning accuracy when the head 12 is positioned on the first type track (adjacent uncorrelated track) is improved. In addition, the improvement in positioning accuracy improves the reliability when writing / reading data to / from the first type track, and the frequency of retries in data writing / reading is reduced, resulting in the operation of the HDD 10. Increases performance.

  2) The speed at which the learning of the correction information for suppressing the eccentric component (synchronous component) of the first type track synchronized with the rotation of the disk 11 is converged, and as a result, the operation performance of the HDD 10 is improved.

  3) With the configuration in which the learning value of the first type track that has passed the inspection in the manufacturing process is stored in the first learning value area 231 of the FROM 23, a condition for determining a track to which an alternative track should be allocated in the manufacturing process is determined. Can be loosened. When the HDD 10 is mainly applied to the electronic device 1 that requires sequential access, the efficiency of the seek operation is improved when the number of alternative tracks is reduced, and as a result, the operation performance of the HDD 10 is improved.

  In the above embodiment, when the area learning value and the track learning value are not equivalent (NO in step 409), the correction information determination process (step 411) is executed. However, it is determined whether the area learning value is not equal to the track learning value, and if the area learning value is not equal to the track learning value is high, an alternative track is assigned to the target track 112 instead of the correction information determination process. It doesn't matter. In this way, the correction information determination process is limited to a track where the area learning value and the track learning value are not equal to each other, and the effects 1) and 2) are further enhanced. However, since the number of alternative tracks increases after the shipment of the HDD 10, the effect of 3) is reduced.

  Further, the alternative track may be secured in the FROM 23 instead of the disk 11. Further, if the area learning value and the track learning value are not equivalent (NO in step 409), instead of the correction information determination process, an alternative track is assigned to the target track 112, and the alternative track is assigned to, for example, the first learning value area 231 in the FROM 23. It may be secured within. That is, the information recorded in the target track 112 is stored in the first learning value area 231 in association with the target track 112 as correction information (second correction information) corresponding to the track learning value. Also good. In this case, accessing the correction information stored in the first learning value area 231 in association with the target track 112 corresponds to accessing the target track 112, so that the access efficiency is significantly improved. However, the capacity of the FROM 23 is increased.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Electronic device, 10 ... HDD (magnetic disk device), 11 ... Disk, 12 ... Head, 13 ... SPM (spindle motor), 14 ... VCM (voice coil motor), 16 ... Motor driver IC, 18 ... Head IC, DESCRIPTION OF SYMBOLS 19 ... Read / write IC, 20 ... HDC (disk controller), 22 ... CPU (main controller), 23 ... FROM (flash ROM), 100 ... Host, 111 ... Servo area, 112 ... Track (data track), 113 ... User data area, Z0 to Z2... Zone (area).

Claims (9)

In the magnetic disk device, the magnetic disk device comprises:
Storage means;
Detecting means for accessing an available data track on a disk in the magnetic disk device and detecting whether a predetermined criterion is satisfied;
Correction information acquisition means for acquiring correction information for use in the predetermined determination criterion when a predetermined data track does not satisfy the predetermined criterion;
Storage means for storing the acquired correction information in the storage means in association with the predetermined data track;
Control means for controlling access to the predetermined data track based on the correction information. The magnetic disk apparatus according to claim 1,
The correction information corresponds to an eccentric component of the predetermined data track. The magnetic disk device according to claim 1,
The storage means acquires correction information corresponding to the correction information stored in the storage means in association with the predetermined data track, and the stored correction information and the acquired correction information are not equivalent. The correction information is updated to the acquired correction information. The magnetic disk apparatus according to claim 1,
The acquired correction information is information recorded in the predetermined data track. The magnetic disk apparatus according to claim 1,
The acquired correction information is information recorded in the predetermined data track,
The control means is configured to access correction information associated with the predetermined data track instead of accessing the predetermined data track. The magnetic disk apparatus according to claim 1,
The detecting means is configured to detect whether the data track to be accessed satisfies the predetermined criterion when accessing the data track to be accessed on the disk. A method for applying correction information when accessing a data track on a disk, the method comprising:
Detecting whether a predetermined criterion is satisfied by accessing an available data track on a disk in the magnetic disk device; and
Obtaining correction information for use in the predetermined determination criterion when a predetermined data track does not satisfy the predetermined determination criterion;
Storing the acquired correction information in a storage unit in association with the predetermined data track;
Controlling access to the predetermined data track based on the correction information. The method of claim 7, wherein
The correction information corresponds to an eccentric component of the predetermined data track. The method of claim 7, wherein
The acquired correction information is information recorded in the predetermined data track,
Instead of the predetermined data track, correction information associated with the predetermined data track is accessed.

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