JP2007213745A - Disk drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve both reliability and performance of an HDD. <P>SOLUTION: An HDC/MPU23 uses a write inhibit value of an (X-y) PES which specifies a narrow allowance range, in a target PES near a 64PES and a 192PES. In other regions, a write inhibit value of an XPES which specifies a wide allowance range is used. Since a burst used by the 64PES and the 192PES changes, servo gain falls. That is, the change of the PES to the amount of physical movement of the head element section 12 becomes small. Squeeze write is prevented by making the write inhibit value severe near the 64PES and the 192PES. Furthermore, by using a different write inhibit value, the fall of performance due to only one severe write inhibit value is prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a disk drive device, and more particularly to write processing control in a disk drive device.

  As data storage devices, devices using various types of media such as optical disks and magnetic tapes are known. Among them, hard disk drives (HDDs) are used as computer storage devices. It has become widespread and has become one of the storage devices that are indispensable in current computer systems. Furthermore, applications of HDDs such as a removable memory used in a moving image recording / reproducing apparatus, a car navigation system, a digital camera, etc. are expanding more and more due to its excellent characteristics.

  An HDD that records and reproduces data by a head element unit performs head positioning control based on servo data formed on a magnetic disk. Each of the tracks formed concentrically on the magnetic disk has a plurality of servo sectors, and each servo sector is composed of servo data and user data. Servo data is recorded on a magnetic disk by a servo writer or the like in the HDD manufacturing process.

  In recent years, as the storage capacity of magnetic disks has increased and the recording density thereof has increased, the intervals between data tracks and servo tracks and the intervals between data sectors have become narrower. As the data track pitch decreases, the tolerance for fluctuations in the radial direction of the head element portion in data writing has decreased.

  In the data writing process on the magnetic disk, data writing is prohibited when the head element portion is outside the permitted range from the target servo address. This prevents the head element unit from overwriting the adjacent data track (squeeze write). Here, the servo address includes a servo track and a position error signal (PES). Strict conditions for this permission range can reduce the possibility of squeeze write, but if the permission range is too strict, data cannot be written, resulting in reduced performance or time.・ Hard error may occur due to out.

  For this reason, it is important to appropriately set the permission range defined by the servo address. One of such methods is proposed in Patent Document 1, for example. Patent Document 1 discloses that an erase band is different between the inner circumference side and the outer circumference side due to head skew, and discloses that different permission ranges are set on the inner circumference side and the outer circumference side according to the target data track. is doing.

That is, a narrow permissible range is set on the side where the erase band is wide and squeeze light is likely to occur, and a wide permissible range is set on the side where the erase band is narrow and unlikely to cause squeeze light. This prevents squeeze writing and suppresses a decrease in HDD performance.
JP 2000-173005 A

  However, the inventors have found that the squeeze-write possibility shift (variation) is not limited to the above, but may be caused by other factors or appear in other modes. In the write processing control, it is important to set a data write permission range in accordance with factors that cause variations in the possibility of squeeze write and how they appear. Alternatively, the write process executes an error recovery process in addition to the normal write process. Also in this error recovery process, it is important to set a permission range from the viewpoint of reliability and performance.

  A disk drive device according to one aspect of the present invention uses a head that accesses a rotating recording disk, an actuator that holds and moves the head, and servo data that the head reads from the recording disk. The head is positioned with respect to the target servo address, a permission range corresponding to the target servo address is determined so as to compensate for a change in servo gain according to the servo address, and the head reads A controller is provided for writing data to the recording disk on condition that the servo address is within the determined permission range from the target servo address. By determining the permission range so as to compensate for the change in servo gain, it is possible to achieve both prevention of squeeze write and maintenance of performance.

  The controller preferably determines the permission range based on the target servo address. As a result, the permitted range can be set in accordance with the servo gain that changes depending on the target servo address.

  Further, the servo address includes a servo track number and a position error signal, and the servo data includes a plurality of bursts used to generate a servo track ID for specifying the servo track and the position error signal. And the controller changes a burst used to generate a position error signal according to a head position, and the controller responds to the target servo address based on the position error signal of the target servo address. It is preferable to determine the permissible range. Thereby, it is possible to effectively cope with a change in servo gain due to a change in burst.

  Further, the controller changes a burst using the reference position error signal value as a boundary, uses at least a first permission range and a second permission range narrower than the first permission range, and the target servo address. It is preferable to use the second permission range on the condition that the position error signal value is a predetermined value near the reference position error signal value. This effectively compensates for a decrease in servo gain in the vicinity of the address where the burst is changed.

  It is preferable that the controller uses the second permission range as a weighting condition that the target data track is in a predetermined range. Alternatively, it is preferable that the controller further determines a permission range corresponding to the target servo address based on a write current of the head. As a result, the occurrence of squeeze / write can be suppressed, and the performance degradation can be more effectively suppressed.

  A disk drive device according to another aspect of the present invention uses a head that accesses a rotating recording disk, an actuator that holds and moves the head, and a servo address that the head reads from the recording disk. The head is positioned with respect to the target servo address, a permission range from the target servo address is determined based on the write current of the head, and the servo address read by the head is within the permission range A controller is provided for writing data to the recording disk on condition that there is a certain condition. By determining the allowable range from the target servo address based on the write current of the head, it is possible to achieve both prevention of squeeze write by the erase band and maintenance of performance.

  The disk drive device further includes a temperature detector, and adjusts the write current according to a detected temperature of the temperature detector, and the controller uses the detected temperature of the temperature detector to set the target servo address. It is preferable to determine the corresponding permitted range. By setting the allowable range using the detected temperature that is the reference for the write current control, the control can be made simpler.

  It is preferable that the controller sets a permissible range that is stricter than the permissible range when the write current is less than the reference value on condition that the write current is larger than the reference value. This effectively prevents squeeze light due to the erase band spreading due to an increase in write current, and suppresses performance degradation due to the use of one permission range. Furthermore, it is preferable that the controller sets a permitted range that is stricter than the permitted range equal to or less than the reference value, with a weighting condition that the target data track is in a predetermined range. As a result, the occurrence of squeeze / write can be suppressed, and the performance degradation can be more effectively suppressed.

A disk drive device according to another aspect of the present invention uses a head that accesses a rotating recording disk, an actuator that holds and moves the head, and servo data that the head reads from the recording disk. The head is positioned with respect to the target data track, a permission range narrower than a reference permission range is set on condition that the target data track is a predetermined data track, and the head reads A controller that writes data to the recording disk on condition that the servo address is within the set allowable range from the target servo address.
By setting a permission range narrower than the standard permission range on condition that the target data track is a predetermined data track, a permission range corresponding to the change in erase band due to head skew is set. The occurrence of squeeze light and the performance degradation due to the use of one narrow permission range can be suppressed.

  The servo address used by the controller includes a servo track number and a position error signal. The controller changes a burst using a reference position error signal value as a boundary, and the position error of the target servo data. A permission range that is stricter than the reference permission range may be set on condition that the signal value is a predetermined value near the reference position error signal value and the write current of the head is larger than the reference current value. preferable. As a result, the occurrence of squeeze / write can be suppressed, and the performance degradation can be more effectively suppressed.

  The controller sets a permission range narrower than the reference permission range on the condition that the target data track is in a predetermined data track range so as to compensate for an erase band change due to head skew. It is preferable to set. As a result, it is possible to suppress the occurrence of squeeze write due to the change of the erase band due to the head skew that changes in accordance with the data track, and the performance degradation due to the use of one narrow permission range.

  A disk drive device according to another aspect of the present invention includes a head for accessing a rotating recording disk, an actuator for holding and moving the head, and an error recovery step in an error recovery process in response to an error in a write process. A permission range that spreads as the progress proceeds is set, and in each error recovery step, data writing to the recording disk is performed on condition that the servo address read by the head is within the set permission range from the target servo address. A controller is provided. By setting a permissible range that expands as the error recovery step progresses, it is possible to suppress the occurrence of squeeze write and to suppress the performance degradation.

  The controller starts the error recovery process using the same permission range as the write process in which an error has occurred, and changes to a permission range wider than the same permission range in a predetermined error recovery step. Is preferred. This can more effectively suppress the occurrence of squeeze write and performance degradation. Furthermore, it is preferable that the controller changes to the wide permission range in an error recovery step of a predetermined execution order. Thereby, control can be facilitated.

  According to the present invention, it is possible to achieve both improvement in reliability of a disk drive device and maintenance of performance.

  Hereinafter, embodiments to which the present invention can be applied will be described. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. Moreover, in each drawing, the same code | symbol is attached | subjected to the same element and the duplication description is abbreviate | omitted as needed for clarification of description.

  In the following, embodiments of the present invention will be described by taking a hard disk drive (HDD) as an example of a disk drive device as an example. The HDD of this embodiment performs data writing on the condition that the servo address read by the head element unit is within the permitted range based on the target servo address. This prevents unwanted overwriting to adjacent data tracks. The HDD according to this embodiment sets a permission range based on the processing conditions in each write process. As a result, both the reliability and performance of the HDD are achieved.

  In order to facilitate understanding of the feature points of this embodiment, first, an outline of the entire configuration of the HDD will be described. FIG. 1 is a block diagram schematically showing the configuration of the HDD 1 according to the present embodiment. As shown in FIG. 1, the HDD 1 includes a magnetic disk 11, which is an example of a recording disk, a head element unit 12, an arm electronic circuit (AE: Arm Electronics) 13, and a spindle motor (SPM) in a sealed enclosure 10. 14, a voice coil motor (VCM) 15, and an actuator 16.

  The HDD 1 further includes a circuit board 20 fixed to the outside of the enclosure 10. On the circuit board 20, a read / write channel (R / W channel) 21, a motor driver unit 22, a hard disk controller (HDC) and an MPU integrated circuit (hereinafter referred to as HDC / MPU) 23, a RAM 24, and a temperature Each IC such as the detector 25 is provided. Each circuit configuration can be integrated into one IC, or can be divided into a plurality of ICs. User data from the external host 51 is received by the HDC / MPU 23 and written to the magnetic disk 11 by the head element unit 12 via the R / W channel 21 and the AE 13. The user data stored in the magnetic disk 11 is read by the head element unit 12, and the user data is output from the HDC / MPU 23 to the external host 51 via the AE 13 and the R / W channel 21. The

  The magnetic disk 11 is fixed to the SPM 14. The SPM 14 rotates the magnetic disk 11 at a predetermined angular velocity. The motor driver unit 22 drives the SPM 14 according to control data from the HDC / MPU 23. Each head element unit 12 is fixed to a slider (not shown). The slider is fixed to the tip of the actuator 16. The actuator 16 is coupled to the VCM 15 and moves in the radial direction on the magnetic disk 11 rotating the head element unit 12 (and slider) by swinging about the swing axis. The motor driver unit 22 drives the VCM 15 in accordance with control data (referred to as DACOUT in this specification) from the HDC / MPU 23.

  The head element unit 12 includes a write element that converts an electric signal into a magnetic field according to data recorded on the magnetic disk 11 and a read element that converts a magnetic field from the magnetic disk 11 into an electric signal. The write current value of the write element changes according to the control value set by the HDC / MPU 23. One or more magnetic disks 11 may be provided, and the recording surface can be formed on one side or both sides of the magnetic disk 11.

  The AE 13 selects one head element unit 12 that accesses the magnetic disk 11 from among the plurality of head element units 12, and amplifies a reproduction signal reproduced by the selected head element unit 12 with a constant gain ( Preamplifier) and send to the R / W channel 21. Also, the recording signal from the R / W channel 21 is sent to the selected head element unit 12. In the read process, the R / W channel 21 amplifies the read signal supplied from the AE 13 to have a constant amplitude, extracts data from the acquired read signal, and performs a decoding process. Data to be read out includes user data and servo data. The decoded read user data is supplied to the HDC / MPU 23. In the write process, the R / W channel 21 code-modulates the write data supplied from the HDC / MPU 23, converts the code-modulated write data into a write signal, and supplies the write signal to the AE 13.

  In the HDC / MPU 23, the MPU operates according to the code loaded in the RAM 24. Along with the activation of the HDD 1, the RAM 24 is loaded with data necessary for control and data processing from the magnetic disk 11 or ROM (not shown) in addition to the code operating on the MPU. The HDC / MPU 23 performs necessary processing related to data processing such as read / write processing control, command execution order management, positioning control (servo control) of the head element unit 12 using a servo signal, interface control, defect management, etc. The entire control of the HDD 1 is executed. The HDC / MPU 23 changes the write current value in the write process based on the temperature detected by the temperature detector 25. As the temperature decreases, the write current increases. As the temperature detector 25, for example, a thermistor can be used. The HDC / MPU 23 according to the present embodiment changes the write inhibit value based on the processing operation condition. This will be described in detail later.

  The recording data on the magnetic disk 11 will be described with reference to FIG. As shown in FIG. 2, the recording surface of the magnetic disk 11 has a plurality of adjacent servo areas 111 extending radially from the center of the magnetic disk 11 and spaced apart by a predetermined angle. A data area 112 is formed between the two servo areas 111. Servo data for controlling the positioning of the head element unit 12 is recorded in each servo area 111. In each data area 112, user data is recorded. On the recording surface of the magnetic disk 11, a plurality of data tracks having a predetermined width in the radial direction and formed concentrically are formed. User data is recorded along the data track. One data track has a plurality of data sectors (user data recording units) between the servo areas 111.

  Each of the plurality of data tracks is grouped into a plurality of zones 113 according to the radial position of the magnetic disk 11. The number of data sectors included in one data track is set for each zone. In FIG. 2, three zones 113a-113c are illustrated. Similarly, the magnetic disk 11 has a plurality of servo tracks having a predetermined width in the radial direction and formed concentrically. Each servo track is composed of a plurality of servo data separated in the data area 112.

  FIG. 3 schematically shows a part of the data area 112 and the servo area 111. The magnetic disk 11 of this embodiment records data according to an adaptive format in which the data track pitch and the servo track pitch are different. The data track pitch is larger than the servo track pitch, and squeeze and off-track writing can be prevented to improve reliability.

  Further, FIG. 3 schematically shows the positions of the write element 121 and the read element 121 at the time of data reading and data writing. In this example, when the head element unit 12 is positioned on the magnetic disk 11, the write element and the read element are at different positions in the radial direction. This difference (distance) in the radial direction between the write element and the read element is called a read / write offset.

  In FIG. 3, a write element 121a and a read element 122a indicate head positions at the time of data reading, and a write element 121b and read element 122b indicate head positions at the time of data writing. Specifically, the read element 122a is positioned at a position for reading the data track DTr_m. On the other hand, the read element 122b is positioned at a position where the write element 121b writes user data to the data track DTr_m-2.

  As described above, when the data track pitch and the servo track pitch are different, the target position of the head element unit 12 is not always the center of the servo track, and the position in the servo track depends on the target position. Different. Therefore, it is necessary to use different bursts according to the target position for positioning control of the head element unit 12.

  FIG. 4A schematically shows a data format of servo data. Servo data consists of servo AGC (Auto Gain Control: AGC), servo address mark (SAM), gray code, servo track ID (SERVO TRACK) that identifies the servo track, and servo within the servo track. A servo sector ID (SERVO SECTOR) for specifying a sector and a burst pattern for fine position control are provided.

  The HDD 1 determines the gain value of AGC using the read amplitude of the servo AGC. The SAM provides timing for the R / W channel 21 to process servo data. The servo track number specifies each servo track, and the servo sector ID specifies each servo sector in the servo track.

  The burst pattern is composed of four bursts A, B, C, and D having different circumferential positions and radial positions. The read element 122 reads in the order of bursts A, B, C, and D. Each burst is arranged from the inner circumference side in the order of bursts A, B, C, and D. The relative position in the servo track can be determined by the amplitude of the reproduction signal of each burst. As shown in FIG. 4B, the position in the servo track is represented by a value called a position error signal (PES) divided into 256 in the radial direction.

  In the servo track, the inner circumference (ID) side end is PES0 and the outer circumference (OD) side end is PES255. The positions of adjacent servo tracks PES0 and PES256 are the same. The center of each servo track is PES128. In this specification, the servo address is specified by a servo track ID, a servo sector ID, and a PES. The servo address in the radial direction of the magnetic disk 11 is specified by the servo track ID and the PES.

  The PES is determined by the burst pattern. Specifically, the HDD 1 of the present embodiment controls the positioning of the main PES (MPES) calculated using the burst A and the burst B and the secondary PES (SPES) calculated using the burst C and the burst D. Used in. MPES is calculated using | A−B | / (A + B). The SPES is calculated using | C−D | / (C + D). Here, each alphabet represents a read amplitude value of each burst. The HDC / MPU 23 changes the PES used according to the head position.

  Specifically, the HDC / MPU 23 uses MPES when the target servo address read by the head element unit 12 is between PES64 and PES192. When the read servo address is in the other area, the HDD 1 uses SPES. As shown in FIG. 4B, the boundary between burst A and burst B in the radial direction is at PES128. Note that MPES and SPES used at the time of track following may be switched in accordance with the target servo address for positioning the head element unit 12.

  Therefore, the HDD 1 uses MPES between PES 64 to PES 192 centered on the PES 128. On the other hand, the boundary between burst C and burst D in the radial direction is at PES0 (255). Therefore, HDD1 uses MPES between PES192 and PES64 centering on PES0. For PES 64 and 192, either MPES or SPES is used according to the design.

  FIG. 5 shows the relationship between the PES and the actual physical movement amount of the head element unit 12. As shown in FIG. 5, in the vicinity of 64 PES and 192 PES, the relationship between the PES and the physical movement amount is different from other regions, and there is a distortion of the relationship. Specifically, the change rate of the physical movement amount with respect to the PES change amount increases in the vicinity of 64 PES and 192 PES.

  In an ideal state, the PES and the physical movement amount have a linear relationship. However, in actual products, these do not satisfy a strict linear relationship. Therefore, it is necessary to correct the value calculated from the actually read burst signal. FIG. 5 shows the relationship between the corrected PES and the physical movement amount. Since MPES and SPES use different bursts, these values are not continuous in the actual HDD 1, and it is necessary to make these values continuous by correction. Distortion in the vicinity of 64 PES and 192 PES is caused by this correction. In particular, this discontinuity becomes more prominent as the track pitch decreases.

  As understood from FIG. 5, in the vicinity of 64 PES and 192 PES, the change amount of PES corresponding to the change of the physical movement amount is small. That is, in practice, the PES does not change so much even though the head element portion 12 is greatly moved in the radial direction of the magnetic disk 11. In this specification, the amount of change in PES with respect to the amount of physical movement is referred to as servo gain. That is, the servo gain is reduced in the vicinity of 64 PES and 192 PES.

  The HDC / MPU 23 specifies the current position of the head element unit 12 using servo data, that is, PES. As described above, the servo gain is reduced in the vicinity of 64 PES and 192 PES. That is, since a large change in the physical movement amount does not appear in the PES, the HDC / MPU 23 cannot accurately detect a large change in the physical movement amount in the vicinity of 64 PES and 192 PES.

  Therefore, the HDC / MPU 23 of this embodiment sets a permission range in which data writing is permitted so as to compensate for this change in servo gain. Specifically, the HDC / MPU 23 sets the permission range according to the PES value of the target servo address (hereinafter referred to as target PES). This permission range will be described. When the head element unit is located outside the permitted range from the target servo address, the HDC / MPU 23 does not write data. That is, the HDC / MPU 23 writes data to the magnetic disk 11 on the condition that the servo address read by the head element unit 12 is within the permitted range from the target servo address.

  FIG. 6 shows an example of the permitted range and the position of the head element unit 12 (read servo address). The permitted range is defined by two boundary PES values (write inhibit values) on the inner and outer peripheral sides of the target servo address. When the head element unit 12 (read element 122) moves away from the target servo address (TARGET) by a write inhibit value (WRITE INHIBIT) or more, the HDC / MPU 23 stops (aborts) the write process.

  FIG. 6 illustrates two permission ranges. The write inhibit value of one permission range is XPES (X is a positive integer) on the inner periphery side and the outer periphery side, and the write inhibit value of another permission range is (X−y) on the inner periphery side and the outer periphery side. ) PES (y is a positive integer). The HDC / MPU 23 selects one permission range according to the target servo address so as to compensate for the change in servo gain. Each circle 114a-114f in FIG. 6 represents a head position (servo address) calculated from each servo data read by the head element unit 12.

  When the PES value read by the head element unit 12 is away from the target servo address by the write inhibit value on the inner circumference or the outer circumference side, the HDC / MPU 23 does not write data. That is, the HDC / MPU 23 does not start data writing before data writing, and stops data writing when data is being written. Thus, the data write condition is that the PES value is within the write inhibit value with reference to the target servo address. By prohibiting / permitting writing using the write inhibit value, data writing (squeeze writing) to the adjacent data track is prevented.

  Specifically, when the HDC / MPU 23 uses the permission range defined by XPES, only the head position 114f is prohibited from writing data. When the HDC / MPU 23 uses the permission range defined by (X-y) PES, the head positions 114e and 114f are prohibited from writing data.

  As described with reference to FIG. 5, the servo gain decreases in the vicinity of 64 PES and 192 PES. The HDC / MPU 23 uses the write inhibit value of the PES that defines a narrow allowable range in the target PES near 64 PES and 192 PES in order to compensate for the change in the servo gain. In other target PES areas, the HDC / MPU 23 uses the XPES write inhibit value that defines a wide permitted range.

  That is, in the vicinity of 64 PES and 192 PES, the head element unit 12 physically moves larger than the PES change. For this reason, squeeze writing can be effectively prevented by reducing the write inhibit value to narrow the permission range and tightening the condition of the write permission.

  The target PES for setting the above-mentioned strict write-inhibit conditions can be set in advance in the design stage. For example, when a specific PES value in the vicinity of 64 and 192 PES is registered in advance, and the PES of the target servo data matches the registered PES, the HDC MPU 23 uses a narrow permitted range. A wide default permission range is used for other target servo data.

  Specifically, for example, an area within a predetermined PES value is registered with reference to 64PES and 192PES, such as (64 ± α) PES and (192 ± β) PES. When the PES of the target servo data is included in the area, the HDC MPU 23 uses a narrow allowable range. Here, α and β are integers of 0 or more, and can be set to 5, for example. α and β can be the same or different values. Further, 64 PES or 192 PES may not be the center of the area where the write inhibit value is narrowed, and the ID side and OD side areas may be different PES values. Note that since the PES used as a target varies depending on the design of the HDD, 64 PES or 192 PES is not necessarily registered.

  The HDC / MPU 23 can use an allowable range of 2 or 3 or more. From the viewpoint of effectiveness and controllability, it is preferable to use two allowable ranges. For example, the HDC / MPU 23 can use a default value and a value obtained by subtracting a reference value from the default value as the write inhibit value. For example, 35 PES is set as the default value, and 5 PES is used as the reference value. The default permission range is target servo address ± 35 PES, and the narrow permission range is target servo address ± 30 PES. Also, the HDC / MPU 23 can use different write inhibit values on the inner circumference side and the outer circumference side. These points are the same in the following other aspects.

  The HDC / MPU 232 can gradually change the reference value according to the target PES value. For example, when the target PES is 64 PES, the write inhibit value is set to 30 PES, and the write inhibit value is gradually changed from 30 PES to 35 PES in the 5 PES areas before and after that. As described above, by setting the permitted range for data writing to compensate for the change in the servo gain of the target servo address, the occurrence of squeeze write at a position where the servo gain is small is suppressed, and all It is possible to suppress the performance degradation caused by narrowing the permission range at the position and the occurrence of a hard error due to time-out.

  The write inhibit control based on the target PES value will be specifically described with reference to the block diagram of FIG. In the data writing process, the MPU 232 determines a VCM current value to be applied to the VCM 15 for positioning the head slider 12, and sets data (DACOUT) representing the value to the motor driver unit 22. The MPU 232 calculates DACOUT from the target position of the head slider 12 and the current head position acquired from the HDC 231.

  The MPU 232 acquires target track information from the host 51 via the HDC 231 and calculates a target position represented by servo data. The HDC 231 determines the current position of the head slider 12 from the servo data (SERVO DATA) acquired from the R / W channel 21 and sends it to the MPU 232. The R / W channel 21 generates servo data from the servo signal (SERVO SIGNAL) transferred from the head slider 12 via the AE 13.

  In writing data to the magnetic disk 11, the HDC 231 transfers write data (WRITE DATA) stored in the buffer 242 to the R / W channel 21 in accordance with an instruction from the MPU 232. The R / W channel 21 code-modulates the write data, further converts the code-modulated write data into a write signal (WRITE SIGNAL), and supplies it to the AE 13. The AE 13 outputs a write current having a value set by the MPU 232 to the head slider 12 in accordance with the signal.

  The MPU 232 monitors the current position of the head slider 12 using servo data in the data writing process. Further, the MPU 232 determines a write inhibit value based on the PES value at the target position. Data writing to the magnetic disk 11 is performed on condition that the deviation between the target position and the current position is within the write inhibit value. When the head element unit 12 moves away from the target by the write inhibit value or more during data writing, the MPU 232 instructs the HDC 231 and the R / W channel 21 to stop the writing process.

  In the above description, the method for compensating for the change in servo gain associated with the switching of the burst to be used has been described. However, the servo gain caused by other reasons such as the servo data format or the method of using the servo data has been explained. By setting a permission range so as to compensate for changes, it is possible to improve both reliability and maintain performance.

  Subsequently, as another preferred embodiment, a method for setting a permission range (write inhibit value) based on a write current will be described. In the above description, the MPU 232 determines the write inhibit value based on the servo gain of the target servo address. Hereinafter, an example in which the write inhibit value is determined based on the write current will be described. FIGS. 8A and 8B schematically show the relationship between the write current and the erase bands 115a and 115b.

  In writing data to the magnetic disk 11, the write element 121 generates a write magnetic field between the two magnetic poles 124a and 124b. This magnetic field spreads not only between the opposing surfaces of the magnetic poles 124a and 124b but also to the outside thereof. The erase bands 115a and 115b are areas where data is erased by a magnetic field extending outside the magnetic poles 124a and 124b outside the original data track 116b where data is written.

  When the write current is small, the widths of the erase bands 115a and 115b are small as shown in FIG. As shown in FIG. 8B, when the write current increases, the width of the erase bands 115a and 115b increases. Therefore, as the write current increases, the adjacent data tracks 116a, 116c on both sides approach the erase bands 115a, 115b. For this reason, under a condition where the write current is large, a slight positional deviation of the head element unit 12 causes overwriting of the adjacent data tracks 116a and 116c by the erase bands 115a and 115b.

  In this embodiment, the HDD 1 determines the write inhibit value so as to compensate for the expansion of the erase band due to the increase in the write current. As understood from the above description, the write inhibit value under the condition of the large write current is set to a value smaller than the write current value of the small write current. As a result, even when the erase bandwidth increases due to an increase in write current, the possibility of squeeze writing of adjacent data tracks can be reduced. Further, by changing the write inhibit value according to the erase bandwidth, it is possible to avoid a decrease in the performance of the HDD 1 due to the strict write inhibit condition.

  The HDD 1 can continuously increase the write inhibit value as the write current increases. Alternatively, the HDD 1 includes two or more discrete write inhibit values registered in advance, and associates each write inhibit value with each of a plurality of write current regions. As the write current shifts to a larger write current region, the corresponding write inhibit value decreases. That is, in any case, when the HDD 1 is larger than the specific write current reference value, the HDD 1 uses a permitted range that is stricter than the permitted range below it.

  The write inhibit control based on the write current will be specifically described with reference to the block diagram of FIG. The HDD 1 controls the write current supplied from the AE 13 to the head slider 12 according to the temperature detected by the temperature detector 25. The HDD 1 determines the write inhibit value using the detected temperature. As a result, the HDD 1 determines the write inhibit value as a function of the write current. The other points are substantially the same as the example described with reference to FIG.

  The MPU 232 acquires temperature data from the temperature detector 25 and determines a write current based on the temperature data. The MPU 232 sets data (WRITE CURRENT VALUE) indicating the determined write current in the register of the AE 13. The AE 13 supplies a write current to the head slider 12 in accordance with the set data.

  For example, the MPU 232 can calculate the write current from the temperature detected by the temperature detector 25 according to a preset continuous function. Alternatively, a plurality of discrete write current values corresponding to a plurality of temperature regions are registered in advance, and the MPU 232 can set the write current corresponding to the temperature region including the detected temperature in the AE 13. In writing data to the magnetic disk 11, the AE 13 outputs a write current having a value set by the MPU 232 to the head slider 12 in accordance with the signal.

  The MPU 232 monitors the current position of the head slider 12 using servo data in the data writing process. Further, the MPU 232 determines the write inhibit value based on the temperature detected by the temperature detector 25. When the head element unit 12 moves away from the target by the write inhibit value or more during data writing, the MPU 232 instructs the HDC 231 and the R / W channel 21 to stop the writing process (ABORT).

  Next, as another preferred embodiment, a method for setting a write inhibit value based on head skew will be described. The HDD 1 according to this aspect changes the write inhibit value based on the target data track. 10A, 10B, and 10C schematically show the relationship between the head skew and the erase band. FIG. 10A shows a state in which the head element unit 12 is positioned on the inner circumference (ID) side track, and FIG. 10B shows a state in which the head element unit 12 is positioned on the center (MD) track. FIG. 10C shows a state in which the head element portion 12 is positioned on a track on the outer periphery (ID) side.

  The head skew angle, which is the angle of the head element portion 12 with respect to the data track, is negative in FIG. 9A, 0 in FIG. 9B, and positive in FIG. 9C. As can be understood from FIGS. 9A to 9C, the widths of the erase bands 115a and 115b vary depending on the head skew angle. With reference to the width of the erase bands 115a and 115b when the head skew angle is 0, in the ID side track, the OD side erase band 115b is wide and the ID side erase band 115a is narrow. On the other hand, in the OD side track, the ID side erase band 115a is wide and the OD side erase band 115b is narrow. The MPU 232 according to the present embodiment has a permission range narrower than the default permission range when the target data track is in a predetermined range so as to compensate for a change in head skew that changes according to the data track. Set.

  Specifically, in order to prevent squeeze writing of adjacent tracks by the erase bands 115a and 115b, the HDD 1 is smaller (severe) write in the data track on the ID side and the OD side than the data track in the MD. • Use the inhibit value. For example, the HDD 1 uses a default value (for example, 35 PES) as the write inhibit value in the data track between the ID side reference data track and the OD side reference data track. On the other hand, the HDD 1 uses a predetermined value (determined from a default value) in a data track on the inner circumference side of the ID side reference data track and a data track on the outer side of the OD side reference data track ( For example, 5PES) is used.

  As described above, by determining the write inhibit value based on the target data track, that is, the head skew, it is possible to effectively prevent the squeeze write due to the erase band that varies depending on the data track. Further, by changing the write inhibit value in accordance with the data track, it is possible to avoid performance degradation due to imposing severe write inhibit conditions on all data tracks.

  Although the above example uses two write inhibit values, three or more write inhibit values may be used. Also, the HDD 1 can continuously change the write inhibit value according to the target data track. The write inhibit value is the largest in the data track with zero skew and decreases as the distance from the data track increases. As described above, in the data tracks other than the head skew 0, the widths of the erase bands 115a and 115b are different between the ID side and the OD side. In such a case, the write inhibit value may be changed between the ID side and the OD side.

  Here, the relationship between the data track and the head skew angle varies depending on the design of the HDD. For example, the head skew angle can be designed to always be negative, or the data track with head skew 0 can be designed to be near the innermost circumference or near the outermost circumference.

  In such a case, for example, the recording surface is divided into two, and the default inhibit value is used in an area where the absolute value of the head skew angle on the inner or outer circumference side is smaller than that of the reference data track. In the region where the absolute value of the head skew angle is large, a write inhibit value obtained by subtracting a predetermined number from the default value is used. For specific processing by each element in the HDD 1, see FIG. 7 except that the reference for determining the write inhibit value is changed from the target PES value to the data track (head skew). The description is substantially the same as that described above, and the description thereof is omitted.

  In the above description, the method of changing the write inhibit value according to several conditions has been described. However, changing the permission range according to a combination of these conditions is one of the preferred embodiments. That is, when a plurality of conditions selected from the servo gain, the write current, and the head skew are simultaneously satisfied, the MPU 232 uses a write inhibit value that is smaller than the default value. For example, when the target PES value and the write current satisfy the above-described condition, or when all three conditions satisfy the above-described condition, the MPU 232 uses a write inhibit value that is smaller than the default value. Thus, by reducing the write-inhibit value when a plurality of weighting conditions are satisfied, it is possible to more reliably prevent performance degradation and hard errors, and suppress the occurrence of squeeze write.

  Next, a method for setting a write inhibit value in an error recovery procedure (ERP) for a write process will be described. The HDD 1 of this example uses an increased write inhibit value (wide permission range) from the ERP step during ERP. In the ERP processing step, squeeze write can be prevented by using a strict write inhibit value, and by reducing the write inhibit condition in the middle of ERP, performance deterioration and write hard error can be prevented. it can.

  As shown in the block diagram of FIG. 11, when an error occurs in the write process, the MPU 232 executes ERP according to the write ERP table 242 stored in the RAM 24. The write ERP table 242 includes a plurality of ERP steps. The MPU 232 sequentially executes the processing indicated by each ERP step. Specifically, the MPU 232 changes the offset value from the original target position, changes the filter parameter (PARAMETERS) of the digital filter in the R / W channel 21, changes the read bias current value (BIAS CURRENT VALUE), etc. Execute. If the error is recovered in any ERP step, the MPU 232 ends the ERP.

  FIG. 12 shows an example of the write ERP table 242. The write ERP table 242 of this example has 64 ERP steps. In the write process before starting the write ERP, the MPU 232 uses a write inhibit value smaller than the default value. The MPU 232 uses two values, a default write inhibit value and a smaller write inhibit value.

  The MPU 232 executes each ERP step up to the third ERP step using a small value (severe condition) write inhibit value. In the ERP steps after the fourth ERP step, the MPU 232 performs each ERP step using a larger default write inhibit value. In this way, in the steps after the reference ERP step, the use of a write inhibit value larger than the write inhibit value in the previous ERP step balances prevention of squeeze write and suppression of performance degradation. be able to.

  In the above example, MPU 232 uses two write inhibit values, but three or more write inhibit values can be used. For example, the MPU 232 sequentially increases the write inhibit value in each of a plurality of predetermined reference ERP steps. Preferably, the MPU 232 starts ERP using the write inhibit value (permitted range) in which a write error has occurred. As a result, error recovery can be achieved by changing elements other than the permitted range, and also the occurrence of squeeze write by expanding the permitted range and the occurrence of a write error by narrowing the permitted range can be prevented.

  From the standpoint of effectiveness and controllability, the MPU 232 preferably changes the write inhibit value in an ERP step having a preset execution order such as the fifth step and the tenth step. Alternatively, the write inhibit value may be changed in an ERP step in which a preselected process is performed. Since using many write inhibit values complicates control, the MPU 232 preferably switches between two write inhibit values.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, the present invention is suitable for an HDD, but can be applied to other disk drive devices.

In this embodiment, it is a block diagram which shows typically the whole structure of HDD. In this embodiment, it is a figure which shows typically the state of the recording data of the recording surface of a magnetic disc. In this embodiment, it is a figure which shows typically the position of the write element at the time of data reading and data writing, and a read element. In this embodiment, it is a figure which shows typically the data format of servo data. In this embodiment, it is a figure which shows typically the relationship between PES and the actual physical displacement of a head element part. In this embodiment, it is a figure which shows an example of a permission range and the position (read servo address) of a head element part. In this embodiment, it is a block diagram which shows typically write-inhibit control based on a target PES value. In this embodiment, it is a figure which shows typically the relationship between a write current and an erase band. In this embodiment, it is a schematic diagram explaining the write inhibit control based on a write current. In this embodiment, it is a figure which shows typically the relationship between a head skew and an erase band. In this embodiment, it is a block diagram which shows typically the element regarding a write ERP process. In this embodiment, it is a figure which shows an example of the light ERP table.

Explanation of symbols

10 Enclosure, 11 Magnetic disk, 12 Head element, 13 AE
14 SPM, 15 VCM, 16 Actuator 20 Circuit board, 21 R / W channel, 22 Motor driver unit 23 HDC / MPU, 24 RAM, 51 Host 111 Servo area, 112 Data area, 113 Zone, 121a, b Write element 122a, b Read element, 231 HDC, 232 MPU, 241 Buffer 242 Write ERP table

Claims (16)

A head for accessing a rotating recording disk;
An actuator for holding and moving the head;
Using the servo data read from the recording disk by the head, the head is positioned with respect to a target servo address, and the target servo is compensated for a servo gain change according to the servo address. A controller that determines a permission range corresponding to an address and writes data to the recording disk on condition that the servo address read by the head is within the determined permission range from the target servo address. When,
A disk drive device comprising:   The disk drive device according to claim 1, wherein the controller determines the permission range based on the target servo address. The servo address includes a servo track number and a position error signal,
The servo data comprises a servo track ID that identifies the servo track and a plurality of bursts used to generate the position error signal;
The controller changes the burst used to generate the position error signal according to the head position,
The controller determines a permission range corresponding to the target servo address based on a position error signal of the target servo address;
The disk drive device according to claim 2.   The controller changes a burst using a reference position error signal value as a boundary, uses at least a first permission range and a second permission range narrower than the first permission range, and sets the position of the target servo address. 4. The disk drive device according to claim 3, wherein the second permission range is used on condition that an error signal value is a predetermined value near the reference position error signal value.   The recording disk drive according to claim 4, wherein the controller further uses the second permission range on condition that the target servo track is in a predetermined range.   The recording disk drive according to claim 1, wherein the controller further determines a permission range corresponding to the target servo address based on a write current of the head. A head for accessing a rotating recording disk;
An actuator for holding and moving the head;
Using the servo address read from the recording disk by the head, the head is positioned with respect to the target servo address, and the permitted range from the target servo address is determined based on the write current of the head A controller that writes data to the recording disk on condition that the servo address read by the head is within the permitted range;
A disk drive device comprising: The disk drive device further includes a temperature detector, and adjusts the write current according to a detected temperature of the temperature detector,
The controller determines a permission range corresponding to the target servo address using a temperature detected by the temperature detector.
The disk drive device according to claim 7.   8. The disk drive device according to claim 7, wherein the controller sets a permissible range that is stricter than a permissible range when the write current is less than the reference value on condition that the write current is larger than the reference value.   10. The disk drive according to claim 9, wherein the controller further sets a permissible range that is stricter than the permissible range when the target data track is in a predetermined range or less than the reference value. apparatus. A head for accessing a rotating recording disk;
An actuator for holding and moving the head;
Positioning the head with respect to a target data track using servo data read from the recording disk by the head, provided that the target data track is a predetermined data track A controller that sets a permission range narrower than a reference permission range and writes data to the recording disk on condition that the servo address read by the head is within the set permission range from the target servo address When,
A disk drive device comprising: The servo address used by the controller comprises a servo track number and a position error signal,
The controller changes a burst using a reference position error signal value as a boundary, and the position error signal value of the target servo data is a predetermined value near the reference position error signal value and the head 12. The disk drive device according to claim 11, wherein a permissible range that is stricter than the standard permissible range is set on condition that the write current is larger than a reference current value.   The controller sets a permission range narrower than the reference permission range on the condition that the target data track is in a predetermined data track range so as to compensate for an erase band change due to head skew. 12. The disk drive device according to claim 11, wherein the disk drive device is set. A head for accessing a rotating recording disk;
An actuator for holding and moving the head;
In the error recovery process in response to an error in the write process, a permissible range that expands as the error recovery step progresses is set, and the servo address read by the head is set from the target servo address in each error recovery step. A controller that writes data to the recording disk on the condition that it is within the permitted range;
A disk drive device comprising:   The controller starts the error recovery process using the same permission range as the write process that caused the error, and changes to a wider permission range than the same permission range in a predetermined error recovery step. The disk drive device according to claim 14.   The disk drive device according to claim 15, wherein the controller changes to the wide permission range in an error recovery step of a predetermined execution order.

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