JP2011008880A - Magnetic disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk device with which risk of data disappearance on the adjacent track is eliminated when it is shocked in writing operation.SOLUTION: The magnetic disk device includes: a head slider including a micro-actuator and having a write head to write information on a storage medium and a plurality of read heads to read information from the storage medium; and an MPU 160 controlling and positioning the read head and the write head in such a way that a geometrical center line connecting the read head and the write head becomes a tangent to a concentric circle of a track for writing, wherein the read head is provided on a read position going ahead of the write head, and the MPU 160 simultaneously performs read processing of data just before writing on a track, being identical to the track on which writing is conducted with the write head, with the read head.

Description

  The present invention relates to a magnetic disk device that detects off-track.

  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 to turn the head on a specific track based on the servo information stored in the servo area on the storage medium.

  Specifically, first, a general outline of a magnetic disk device will be described. A magnetic disk device having a hard disk is connected to a host device such as a PC (Personal Computer) via a host interface. Further, the magnetic disk device internally performs data read / write operations on tracks arranged concentrically with respect to the disk medium. A plurality of servo areas are radially formed on the disk medium so as to penetrate concentric circles in order to be positioned on each track, and the read head reads this servo information and tracks on a predetermined track. I am letting.

  In recent years, with the increase in track density, the possibility of erasing the data of the adjacent track has increased, so measures such as increasing the servo sampling frequency by increasing the number of servo areas have been taken. For example, in a 2.5-inch disk device, the number increases from about 150 to about 250 per circumference. For this reason, the track width becomes narrower, and the write head moves to the adjacent track due to the impact received during the write operation, and as a result, writing is performed on the adjacent track, and the data on the adjacent track is lost. There is an increased risk of enduring.

  In order to avoid such a situation, as a technique for performing positioning control with high accuracy, when writing processing is performed with the head on the front surface of the storage medium, the servo information is read with the head on the back surface of the storage medium and the head Has been proposed (for example, Patent Document 1).

  In addition, a servo track for storing servo information is provided between data tracks for storing user data, and the servo information is read by a read head dedicated to the servo track, so that data is read by the read head while the head is on-track. A technique for reading out has also been proposed (for example, Patent Document 2).

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

  However, the technique of Patent Document 1 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. Further, in the technique of Patent Document 2, it is possible to increase the accuracy of off-track detection by narrowing the interval between servo tracks, but this causes a problem of reducing the data capacity that can be written to the storage medium.

  In addition, these techniques cannot completely prevent off-tracking. For example, a disk enclosure that stores a disk of a disk device and a voice coil motor unit that controls a head actuator in the disk enclosure are generally manufactured from different metals. When a change in temperature is applied, each metal expands and contracts, but an impact may occur momentarily to release the strain due to the difference in expansion and contraction. Such an impact is high frequency and cannot be detected at the servo sampling interval. Therefore, if such an impact occurs during the write operation, the write operation is erroneously performed on the adjacent track.

  The present invention has been made in view of the above, and an object of the present invention is to provide a magnetic disk device that can eliminate the risk of data loss of adjacent tracks when subjected to an impact during a write operation.

  In one aspect, a magnetic disk device disclosed in the present application includes a micro-actuator, a head having a write head for writing information to a storage medium, and a plurality of read heads for reading information from the storage medium, and the read head And a control unit for positioning and controlling the geometric center line connecting the write head and the concentric circle of the track to be written, and the read head precedes the write head. The control unit is performing writing processing by the read head and simultaneously reading data on the same track immediately before writing by the read head.

  According to one aspect of the magnetic disk device disclosed in the present application, there is an effect that it is possible to eliminate the risk of data loss of adjacent tracks when receiving an impact during a write operation.

FIG. 1 is a diagram illustrating a configuration of a head included in the magnetic disk device 100 according to the first embodiment. FIG. 2 is a diagram illustrating the head in an on-track state. FIG. 3 is a diagram showing angles formed between the read head 11 and the write head 12 and the track. FIG. 4 shows the positional relationship between the head and the track. FIG. 5 is a diagram showing an arrangement relationship between the read head 11 and the write head 12. FIG. 6 is a diagram showing the positional relationship of the head on the track. FIG. 7 is a diagram showing the positional relationship of the head on the track. FIG. 8 is a side view of the head slider 10 and the track 30. FIG. 9 is a block diagram illustrating the internal structure of the magnetic disk device 100 according to the first embodiment. FIG. 10 is a functional block diagram showing functions of the MPU 160. As shown in FIG. FIG. 11 is a flowchart of a write process performed by the magnetic disk device 100 according to the first embodiment. FIG. 12 is a diagram illustrating the occurrence of a write stop condition. FIG. 13 is a block diagram of the internal structure of the magnetic disk device 300 according to the second embodiment. FIG. 14 is a functional block diagram illustrating functions of the MPU 260. FIG. 15 is a diagram illustrating the occurrence of a write stop condition.

  Embodiments of a magnetic disk device disclosed in the present application will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  First, the external configuration of the magnetic disk device 100 according to the first embodiment will be described. FIG. 1 is a diagram illustrating the configuration of the head actuator 5 included in the magnetic disk device 100 according to the first embodiment. As shown in FIG. 1, the head actuator 5 includes an actuator 14, an arm 1, a microactuator 13, and a head slider 10. The head slider 10 includes a read head 11 and a write head 12. Further, as shown in the figure, the read head 11 is disposed at a position preceding the write head 12 on the track. Hereinafter, the read head 11 and the write head 12 may be collectively referred to simply as “head”.

  FIG. 2 is a diagram illustrating the head in an on-track state. As shown in the figure, the center line connecting the read head 11 and the write head 12 forms a tangent to the track 30 that is on-track, and the read head 11 and the write head 12 are on the same track 30. Show.

  FIG. 3 is a diagram showing angles formed between the read head 11 and the write head 12 and the track. In this figure, the center line A connecting the read head 11 and the write head 12 forms the tangent line B of the on-track 30 by rotating the head using the microactuator 13. In other words, the microactuator 13 causes the yaw angle formed between the center line A connecting the read head 11 and the write head 12 to the track 30 to be approximately 0 degrees, so that the read head 11 and the write head 12 are It is located on the same track 30.

  Strictly speaking, since there is a distance between the read head 11 and the write head 12, the on-track 30 and the center line connecting the read head 11 and the write head 12 are as shown in FIG. It becomes the relationship which comprises an arc and a string. However, if the radius of the circle drawn by the track 30 is compared with the distance between the read head 11 and the write head 12, the distance between the read head 11 and the write head 12 is much shorter. The following description will be made assuming that the track 30 is a tangent line.

  Next, the arrangement relationship between the read head 11 and the write head 12 will be described. FIG. 5 is a diagram showing that the read head 11 and the write head 12 are on the same track 30a. In general, if an impact is applied during a write operation in this state, it is assumed that the head is shifted to the adjacent track 30b as shown in FIG. 6, and the data of the adjacent track 30b is lost as shown in FIG. It is assumed that FIG. 7 shows that when the data of the adjacent track 30b is lost, the off-track is detected and the writing operation is stopped.

  FIG. 8 is a side view of the head slider 10 and the track 30 included in the magnetic disk device 100 according to the first embodiment. As shown in the figure, the read head 11 and the write head 12 included in the head slider 10 are arranged on the same track 30, and the head slider 10 advances on the track 30 in the direction of the arrow. Therefore, the read head 11 can read already written data even during the write operation. An arrow C indicates reading of data already written by the read head 11, and an arrow D indicates writing of new data by the write head 12. In addition, as shown in this figure, the track density is variable for each surface or even on the same surface, and the track interval is variable depending on the track position. This is always a readable track.

  Next, the internal structure of the magnetic disk device 100 will be described. FIG. 9 is a block diagram illustrating the internal structure of the magnetic disk device 100 according to the first embodiment. As shown in the figure, 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 referred to as “host”). Control unit 120, buffer control unit 130, buffer memory 131, nonvolatile memory 132, format control unit 140, read channel 150, MPU (Micro Processing Unit) 160, memory 170, program The memory 180, the servo control unit 190, and the GAIN monitoring unit 200 are included.

  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 includes a read head 11 and a write head 12. The read head 11 reads 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.

  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 signal read by the read head 11 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 GAIN monitoring unit 200 confirms the GAIN value or Viterbimetric margin value of the signal read by the read head 11, or the change rate of the GAIN value or Viterbimetric margin value or other signal quality. Detect possible values.

  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 program memory 180 stores parameters necessary for firmware control using a flash ROM and a RAM.

  The memory 170 and the nonvolatile memory 132 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.

  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 a MCU (Micro Controller Unit) or a CPU (Central Processing Unit).

  Here, the functions of the MPU 160 will be described. FIG. 10 is a functional block diagram showing functions of the MPU 160. As shown in FIG. As shown in the figure, the MPU 160 includes a positioning control unit 161, a reading unit 162, a writing unit 163, a GAIN value acquisition unit 164, a determination unit 165, a write stop execution unit 166, and a write resumption execution unit 167. And mainly.

  When receiving a command from the host device, the positioning control unit 161 analyzes the command and calculates a target position on the magnetic storage medium 111 for reading or writing data. Based on the servo information read from the magnetic storage medium 111 by the read head 11, the current position of the head is calculated.

  Then, the positioning control unit 161 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 the generated VCM control signal is used. Output to the servo controller 190. Then, the arm 1 is rotated on the magnetic storage medium 111 by the VCM 112 to position the head.

  The reading unit 162 reads user data, servo information, and the like stored in the magnetic storage medium 111 read by the read head 11.

  The writing unit 163 writes the write information to the magnetic storage medium 111 by the write head 12 according to the write information received from the host IF control unit 120.

  The GAIN value acquisition unit 164 acquires the GAIN or Viterbimetric margin value detected by the GAIN monitoring unit 200 from the GAIN monitoring unit 200.

  The determination unit 165 checks whether or not the GAIN or Viterbimetric margin value detected by the GAIN monitoring unit 200 is equal to or greater than a predetermined value, and if it is equal to or greater than the predetermined value, writes that it is off-track It is determined that a write stop condition that is a condition for canceling the write is satisfied. Further, even when the GAIN or Viterbimetric margin value is not equal to or greater than a predetermined value and does not satisfy the write stop condition, the current position and the target position are collated based on the servo information read by the reading unit 162. It is determined whether or not the write stop condition is satisfied.

  When the determination unit 165 determines that the write stop condition is satisfied, the write cancel execution unit 166 cancels the writing by the writing unit 163.

  The write restart execution unit 167 performs write restart control. Specifically, the write restart execution unit 166 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 write execution control unit 167 restarts the data read process or write process after the head is on-track.

  Next, write processing by the magnetic disk device 100 according to the first embodiment will be described. FIG. 11 is a flowchart of a write process performed by the magnetic disk device 100 according to the first embodiment.

  The reading unit 162 receives the reading instruction from the host IF control unit 120, and starts the reading process of sector data by the read head 11 (step S10). Subsequently, the writing unit 163 receives a write instruction from the host IF control unit 120, and starts a process of writing sector data to the magnetic storage medium 111 (step S11).

  The GAIN value acquisition unit 164 detects the GAIN value, Viterbimetric margin, or other value that can confirm the signal quality of the signal read by the read head 11 (step S12).

  The determination unit 165 receives the GAIN or Viterbimetric margin value detected from the GAIN monitoring unit 200, checks whether or not the value exceeds the threshold, and determines whether or not the write stop condition is satisfied (step S1). S13).

  Here, a specific determination method will be described. The write stop condition satisfies the write stop condition when the rate of change in the increase in the GAIN or Viterbimetric margin value exceeds a predetermined threshold. FIG. 12 is a diagram illustrating the occurrence of a write stop condition. FIG. 12 shows the relationship between the GAIN or Viterbimetric margin value and the threshold value. In this figure, the horizontal axis represents time (Time), and the vertical axis represents GAIN or Viterbimetric margin values. Here, since the value of GAIN or Viterbimetric margin exceeds the threshold value at time T1, it indicates that a write stop condition has occurred.

  If the determination unit 165 determines that the write stop condition is satisfied (step S13: Yes), the determination unit 165 transmits an error stop to the write stop execution unit 166, and the write stop execution unit 166 executes the write stop (step S16). ).

  On the other hand, if the determination unit 165 determines that the write stop condition is not satisfied (step S13: No), the determination unit 165 determines whether the write stop condition based on the servo information is satisfied (step S14). If the determination unit 165 determines that the write stop condition based on the servo information is satisfied (step S14: Yes), the determination unit 165 transmits an error stop to the write stop execution unit 166, and the write stop execution unit 166 executes the write stop. (Step S16). Here, the write stop condition is determined based on the servo information, but other conventional techniques can be used as long as it is a means for determining the write stop condition.

  On the other hand, when the determination unit 165 determines that the write stop condition based on the servo information is not satisfied (step S14: No), the writing unit 163 confirms whether or not the writing is completed (step S15) and completes. If yes (step S15: Yes), the writing is terminated. If the writing has not been completed (step S15: No), the process returns to step S12, and the determination process by the determination unit 165 is repeated.

  Note that the signal detected by the GAIN monitoring unit 200 is already written data, but the data is generally not written uniformly in the sector, and is generally not written in the vicinity of the sector pulse. Is. Accordingly, the GAIN or Viterbi margin value at the time of reading is detected at the same timing as the normal data reading timing. That is, this determination process is performed in the PLL area, the data area, and the PAD area. As a result, the conventional read processing by the read head can be used as it is.

  In addition, initial value data can be written in advance in a factory in an area reserved for sector replacement processing in the magnetic storage medium 111. As a result, when sector data is written to the replacement area by alternation processing, writing is performed in units of one sector. By checking the GAIN or Viterbi margin of the initial data previously written, It can be used for off-track detection.

  In the current disk apparatus, there can be about 10 sectors or more in one servo frame, but if this method is used, data can be protected from an impact with a frequency higher than the servo sampling frequency.

  As described above, in the first embodiment, the off-track detection by the read head is performed prior to the writing process by the write head, and the write operation is stopped when the off-track is detected. As a result, it is possible to eliminate the risk of continuation of writing and loss of data on adjacent tracks when the track is subjected to an impact during a write operation and is off-tracked, so that the quality of the disk device can be improved.

  In the magnetic disk device 100 according to the first embodiment, the GAIN value acquisition unit 164 acquires a GAIN or viterbimetric margin value from the GAIN monitoring unit 200, and the determination unit 165 sets a write stop condition based on the value. Judgment was made on whether or not to satisfy. On the other hand, in this embodiment, it is determined whether or not the write stop condition is satisfied based on the rate of change in the increase in the GAIN or Viterbimetric margin value.

  Since the external configuration and internal configuration of the magnetic disk device 300 according to the second embodiment are the same as those of the magnetic disk device 100 according to the first embodiment, the description thereof is omitted.

  First, the internal structure of the magnetic disk device in this embodiment will be described. FIG. 13 is a block diagram of the internal structure of the magnetic disk device 300 according to the second embodiment. As shown in the figure, the magnetic disk device 300 includes a head slider 10, a magnetic storage medium 111, a VCM 112, an SPM 113, a head IC 114, a shared bus 115, a host IF control unit 120, a buffer control unit 130, and the like. , A buffer memory 131, a nonvolatile memory 132, a format control unit 140, a read channel 150, an MPU 260, a memory 170, a program memory 180, a servo control unit 190, and a GAIN monitoring unit 200.

  Since the internal configuration of the magnetic disk device 300 according to the second embodiment is the same as that of the magnetic disk device 100 according to the first embodiment except for the MPU 260, the description thereof is omitted. Hereinafter, the MPU 260 will be described.

  FIG. 14 is a functional block diagram illustrating functions of the MPU 260. As shown in the figure, the MPU 260 includes a positioning control unit 161, a reading unit 162, a writing unit 163, a GAIN value acquisition unit 264, a determination unit 265, a write stop execution unit 166, and a write resumption execution unit 167. And mainly. Here, the GAIN value acquisition unit 264 and the determination unit 265, which are different functions from the first embodiment, will be described.

  The GAIN value acquisition unit 264 acquires the change rate of the GAIN or Viterbimetric margin value detected by the GAIN monitoring unit 200, that is, the time derivative of the GAIN or Viterbimetric margin from the GAIN monitoring unit 200.

  The determination unit 263 checks whether the change rate of the GAIN or Viterbimetric margin value detected by the GAIN monitoring unit 200 is equal to or greater than a predetermined value. Is determined. Further, the current position and the target position are collated based on the servo information read by the reading unit 162, and it is determined whether or not the write stop condition is satisfied. Here, the write stop condition is determined based on the servo information, but other conventional techniques can be used as long as it is a means for determining the write stop condition.

  Next, write processing by the magnetic disk device 300 according to the second embodiment will be described. The procedure of the writing process by the magnetic disk device 300 according to the second embodiment is the same as the procedure of the writing process by the magnetic disk device according to the first embodiment, and therefore the difference from the first embodiment will be described with reference to FIG. explain.

  In this embodiment, in step S12, the GAIN value acquisition unit 264 detects the change rate of the GAIN value or the change rate of the viterbimetric margin value (step S12).

  In this embodiment, in step S13, the determination unit 265 receives the change rate of the increase in the GAIN or Viterbimetric margin value detected from the GAIN monitoring unit 200, and determines whether the value exceeds the threshold value. It is confirmed and it is determined whether or not the write stop condition is satisfied (step S13).

  FIG. 15 shows the relationship between the change rate of the increase in the GAIN or Viterbimetric margin value and the threshold value. In this figure, the horizontal axis represents time (Time), and the vertical axis represents the change rate of GAIN or Viterbimetric margin. Here, the change rate of the increase in the GAIN or Viterbimetric margin value exceeds the threshold at time T2, indicating that a write stop condition has occurred at time T2.

  As described above, in the first embodiment, the off-track detection by the read head is performed prior to the writing process by the write head, and the write operation is stopped when the off-track is detected. As a result, it is possible to eliminate the risk of continuation of writing and loss of data in adjacent tracks when the track is subjected to an impact during a write operation and is off-tracked, and the quality of the disk device can be improved.

1 Arm 5 Head Actuator 10 Head Slider 11 Read Head 12 Write Head 30 Track 31 Sector 100, 300 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 132 Nonvolatile Memory 140 Format Control Unit 150 Read Channel 160, 260 MPU
161 Positioning Control Unit 162 Reading Unit 163 Writing Unit 164, 264 GAIN Value Acquisition Unit 165, 265 Judgment Unit 166 Write Cancel Execution Unit 167 Write Resume Execution Unit 170 Memory 180 Program Memory 190 Servo Control Unit 200 GAIN Monitoring Unit

Claims (6)

A head slider comprising a microactuator and 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 controls positioning so that a geometric center line connecting the read head and the write head is tangent to a concentric circle of a track to be written; and the read head precedes the write head Is provided at the readout position,
The controller is performing writing processing by the read head, and simultaneously reading data on the same track immediately before writing by the read head;
A magnetic disk drive characterized by The control unit measures a signal value that is a gain or a Viterbimetric margin at the time of reading by the read head, and stops a writing operation when a value equal to or greater than a predetermined value is detected.
The magnetic disk apparatus according to claim 1. When the control unit detects that the time derivative of the measured signal value is equal to or greater than a predetermined value, the control unit stops the writing operation;
The magnetic disk apparatus according to claim 2. The controller stops the write operation when a value equal to or greater than a predetermined value is detected for a certain period;
The magnetic disk apparatus according to claim 2 or 3, wherein The control unit performs read processing in an area where user sector data can be recorded,
The magnetic disk device according to claim 2, wherein: The control unit performs read processing in a predetermined area for replacement processing,
The magnetic disk device according to claim 2, wherein:

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