JP2007087454A - Method for recording servo pattern, method for manufacturing disk apparatus and disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the yield of a disk apparatus by accuarately reading out a servo pattern. <P>SOLUTION: An HDD 1 comprises a disk and a plurality of head element parts each of which is provided with a write element for recording a pattern in the disk and a read element for reading out the pattern recorded in the disk. In the case of recording a servo pattern for controlling the positioning of heads by SSW, the HDD 1 allows the write elements of respective heads to record the prescribed pattern, allows the read elements of respective head to read out the pattern and calculates the writing width of the write element of each head and the amplitude of the read pattern. Then the head in which the amplitude is a prescribed threshold and more and the writing width is maximum is selected. While reproducing the recorded servo pattern by the read element of the selected head, the servo pattern is successively recorded by the write elements of respective heads. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a servo pattern recording method, a disk device manufacturing method, and a disk device that can record and reproduce more accurately.

  As data storage devices, devices using various types of media such as optical disks and magnetic tapes are known. Among them, a hard disk drive (HDD) is widely used as a computer storage device, and is one of the storage devices indispensable in the current computer system. Furthermore, not only computer systems, but also the use of HDDs, such as moving image recording / playback devices, car navigation systems, mobile phones, and removable memories used in digital cameras, are increasingly expanding due to their superior characteristics. .

  A magnetic disk used in the HDD has a plurality of tracks formed concentrically, and servo data and user data are stored in each track. Data can be written or read by accessing a desired area (address) in accordance with servo data by a head element portion formed of a thin film element. In the data reading process, a signal read from the magnetic disk by the head element unit is subjected to predetermined signal processing such as waveform shaping and decoding processing by a signal processing circuit and transmitted to the host. Transfer data from the host is similarly processed by the signal processing circuit and then written to the magnetic disk.

  As described above, each track has a user data area for storing user data and a servo pattern area for storing servo data. The servo pattern is composed of a cylinder ID, a sector number, a burst pattern, and the like. The cylinder ID indicates a track address, and the sector number indicates a sector address in the track. The burst pattern has relative position information of the magnetic head with respect to the track.

  Servo patterns are formed in a plurality of sectors spaced apart in the circumferential direction on each track, and the servo patterns of each sector across all tracks have the same position (phase) in the circumferential direction. Reading or writing data to or from the magnetic disk is executed while confirming the position of the magnetic head based on the servo data while the magnetic disk is rotating.

  The servo pattern is written on the magnetic disk in the factory before the HDD as a product is shipped. Conventional typical servo pattern writing is performed using a servo writer as an external device. The HDD is set in the servo writer, the servo writer positions the head in the HDD by a positioner (external positioning mechanism), and writes the servo pattern generated by the servo pattern generation circuit to the magnetic disk.

  Currently, the servo data write process (Servo Track Write: STW) occupies a major position in the HDD manufacturing cost. In particular, in recent years, competition for increasing the capacity of HDDs has intensified, and TPI (Track Per Inch) has been increasing accordingly. As the TPI increases, the number of tracks increases and the track width decreases. These increase the STW time and increase the precision of the servo writer, which increases the STW cost. In order to reduce this cost, servo writer cost reduction, STW time reduction, etc. are being promoted.

  Therefore, an SSW (Self Servo Write) method for writing a servo pattern using the mechanism of the HDD main body is used. The SSW uses only the HDD body as the mechanical part, controls the spindle motor and voice coil motor (VCM) in the HDD from an external circuit, and the HDD itself writes a servo pattern under the control of the external circuit. Thus, the cost of servo writing is reduced (see, for example, Patent Document 1).

  As an SSW technique, the servo element already written on the inner circumference side or the outer circumference side is utilized by utilizing the fact that the radial position of the read element and the write element in the head element portion is different (this is called a read / write offset). It is known that positioning is performed while a pattern is read by a read element, and a write element writes a new servo pattern on a track away from the read / write offset.

Normally, in an HDD having a plurality of head element units, one head element unit is selected, and the read element of the selected head element unit is used. The selected head element portion is called a propagation head. At this time, the head element portion having the widest writing width is selected as the propagation head. The reason is mainly to prevent squeeze. When a propagation head having a narrow writing width is selected, the read head of the head element section reads and positions a servo pattern having a narrow writing width, thereby locally narrowing the track width. Then, adjacent tracks overlap each other, and the data on the other track is overwritten and erased by one writing, and the data on the other track cannot be read (for example, patents). References 2 and 3).
JP 2003-141835 A Japanese National Patent Publication No. 10-504128 Japanese Patent Publication No. 8-212733

  However, even if the head element with the widest write width is selected as the propagation head as described above during servo writing, the servo pattern written on the outer circumference side during servo writing will be In some cases, a deviation occurs, the amplitude of servo data to be read is reduced, and a read / write error (VGA (Variable Gain Amplifier) abort) occurs.

  The present invention has been made to solve such problems, and a servo pattern recording method and a disk device that can improve the yield of the disk device by reading the servo pattern more accurately. It is an object to provide a manufacturing method and a disk device.

  In order to achieve the above-described object, a servo pattern recording method according to the present invention includes a disk, a recording element that records a pattern on the disk, and a plurality of heads that include a reproducing element that reads the pattern recorded on the disk. A servo pattern recording method for positioning control of the head in a disk device having: a result of recording a predetermined pattern by the recording element of each head and reading the pattern by the reproducing element Based on the above, the write width of the recording element of each head and the amplitude of the read pattern are calculated, one head is selected based on the value of the write width and amplitude, and the servo pattern previously recorded is Positioning control of each head is performed while reproducing with the reproducing element of the selected head, and servo performance is recorded with the recording element of each head. One in which sequentially to record over emissions.

  Conventionally, when recording a servo pattern with a recording element while reproducing with a reproducing element, a reproducing element of a head having a recording element with the largest writing width among a plurality of heads was used. In the present invention, by considering not only the write width but also the amplitude of the pattern, the head can be selected in consideration of both the characteristics of the recording element and the reproducing element.

  In this case, when selecting the head, it is preferable to select the head having the largest writing width among those having the amplitude equal to or larger than a predetermined amplitude threshold, and the read capable of obtaining the amplitude equal to or larger than the predetermined threshold. By selecting the head having the head, the servo pattern can be read accurately and the positioning accuracy can be improved.

  Further, when calculating the write width and amplitude, a plurality of the predetermined patterns are recorded, and an average value of the results of reading the predetermined patterns is obtained, whereby the head can be selected more accurately.

  Further, when the predetermined pattern is read out, the reading element is read out on the predetermined pattern while being shifted at predetermined intervals, and a profile is created in which the amplitude value of the read signal is taken on the vertical axis with the shift amount as the horizontal axis. The write width and amplitude can be calculated based on the profile, and the write width and amplitude can be easily obtained.

  Furthermore, the maximum amplitude value obtained by the profile can be set as the amplitude, and the width of the profile at a position ½ of the amplitude can be set as the writing width, and parameters of the amplitude and the writing width can be easily obtained. .

  A manufacturing method of a disk device according to the present invention stores a plurality of heads including a disk, a recording element for recording a pattern on the disk, and a reproducing element for reading the pattern recorded on the disk, in the housing, A method of manufacturing a disk device, wherein a control circuit for controlling writing and reproduction of a head is mounted, and a servo pattern for recording and controlling positioning of the plurality of heads on the disk is recorded by the plurality of heads. When recording a pattern, a predetermined pattern is recorded by the recording element of each head, and based on a result of reading the pattern by the reproducing element, a writing width of the recording element of each head and a read pattern And select one head based on the write width and the amplitude value, and the previously recorded servo The controlled positioning of each head while playing a turn at regeneration device of said selected head by the recording element of each head in which sequentially records servo patterns.

  According to the present invention, servo data can be recorded with high accuracy by selecting the head in consideration of the characteristics of the recording element and the reproducing element, and thus the manufacturing yield of the disk device can be improved.

  A disk device according to the present invention includes a disk, a plurality of heads each including a recording element that records a pattern on the disk and a reproducing element that reads a pattern recorded on the disk, and servos the disk by the own head. A disk device for recording a pattern, the recording element for recording a predetermined pattern, the reproducing element for reading the pattern, and the writing width of the recording element of each head based on the pattern reading result of the reproducing element And the amplitude of the read pattern, and a head selection unit that selects one head based on the calculation result, and the previously recorded servo pattern in the reproduction element of the one head selected by the head selection unit Each head is positioned and controlled during playback, and servo patterns are sequentially recorded by the recording elements of each head. Those having a part.

  According to the present invention, it is possible to provide a servo pattern recording method, a disk device manufacturing method, and a disk device that can improve the yield of the disk device by reading the servo pattern more accurately.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 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.

  The present embodiment relates to self-pattern writing to a medium in a data storage device, that is, a process of writing a new pattern on the basis of a pattern written on the medium by itself, particularly when writing a self-pattern using a plurality of heads. In this case, it is necessary to select one read head, and by appropriately selecting the read head at this time, a decrease in manufacturing yield due to a self-pattern writing failure is suppressed. In the present embodiment, the present invention will be described by taking as an example a servo pattern self-writing process in a hard disk drive (HDD) which is an example of a data storage device.

  In the HDD, self-servo write (SSW) is known in which a servo pattern is written using its internal mechanism. In the HDD according to the preferred embodiment, the function performed by the external circuit in the conventional SSW is incorporated in the internal circuit itself on the product card (the board on which each IC of the HDD as a finished product is mounted). . Thus, the HDD can execute the servo pattern writing process on the magnetic disk substantially only by the internal configuration without directly depending on the servo writer device as an external device. In this embodiment, this method is called TSSW (True Self Servo Write). The HDD writes a servo pattern on the magnetic disk by a function implemented in an internal circuit in response to a start signal from an external control device.

  In the present embodiment, the TSSW will be described as an example. However, the present invention can be applied even to an SSW by an external circuit or a servo write by a servo track writer. That is, when writing a servo pattern on a disk by a plurality of head element units, by applying the present invention and selecting an appropriate propagation head, an accurate servo pattern is written, and the product yield in subsequent manufacturing tests. Can be improved.

  As described above, in the case of having a plurality of head element portions in SSW or the like, the head element portion having the widest writing width has been selected as the propagation head. However, even if the head element portion having the widest write width is selected as the propagation head, a defect may be found in various manufacturing tests after writing the servo pattern. After the servo pattern is written, various inspection processes such as a normal function test, SRST (Self Run Self Test), and final test are provided. In the function test, processing such as adjusting each parameter used in the HDD head or the like is performed. In SRST, data is written and read at high temperatures when the HDD is confident, and it is tested whether data can be read and written correctly. Data is written to and read from all tracks on the disk, and the surface of the disk is damaged. For example, a surface analysis test (SAT) for detecting a defective area such as the occurrence of a defect, a fill data for testing whether or not a write error occurs by writing data on all tracks of the disk, and the like are performed. In particular, Filldata tests whether or not a write error occurs, and if a servo pattern is not correctly recorded or cannot be read, a write error occurs. Even when the head element portion having the widest write width is selected as the propagation head, the write error may occur.

  Thus, as a result of intensive studies by the inventors of the present application, it has been found that one of the causes of this write error is that the servo pattern shifts especially when the bit rate increases on the outer peripheral side. In order to solve this problem, not only the write head characteristic of the write width but also the read head characteristic is taken into consideration in selecting the propagation head, thereby improving the servo pattern read performance and increasing the positioning accuracy. As a result, it has been found that the phase shift of the servo pattern can be reduced. As a result, the BPI increases and the write error that frequently occurs due to the conventional phase shift becoming more conspicuous on the outer peripheral side where the rate is high can be reduced, and the yield can be improved.

  Specifically, a propagation head is selected by adding a condition whether or not an amplitude value of a read signal when a pattern is read out is a predetermined value or more to the write width condition. As a result, write errors caused mainly by the servo pattern can be drastically reduced, and the yield of HDD manufacturing can be greatly improved.

  First, before explaining the method of selecting a propagation head and TSSW processing in the present embodiment, an outline of the overall configuration of the HDD that executes the TSSW of the present embodiment will be described. FIG. 1 is a block diagram showing a schematic configuration of the HDD 1. The HDD 1 includes a magnetic disk 11 as an example of a medium (recording medium), a head element section 12, an arm electronic circuit (arm electronics: AE) 13, a spindle motor (SPM) 14, a voice A coil motor (VCM) 15 and an actuator 16 are provided.

  The HDD 1 includes a circuit board 20 that is 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, etc. Each IC is provided. Each circuit configuration can be integrated into one IC or can be divided into a plurality of ICs.

  In a normal use state, write data from the external host 51 is received by the HDC / MPU 23 and is transferred to the magnetic disk 11 which is a non-volatile medium by the head element unit 12 via the R / W channel 21 and the AE 13. Written. Read data stored in the magnetic disk 11 is read by the head element unit 12, and the read data is output from the HDC / MPU 23 to the external host 51 via the AE 13 and the R / W channel 21. The

  Next, each component of the HDD 1 will be described. The magnetic disk 11 is fixed to the SPM 14. The SPM 14 rotates the magnetic disk 11 at a predetermined speed. The motor driver unit 22 drives the SPM 14 according to control data from the HDC / MPU 23. The magnetic disk 11 of this example has recording surfaces for recording data on both sides, and a head element unit 12 corresponding to each recording surface is provided.

  Each head element unit 12 is fixed to a slider (not shown). The slider is fixed to the actuator 16. The actuator 16 is connected to the VCM 15, and swings about the rotation axis to move the head element unit 12 (and the slider) in the radial direction on the magnetic disk 11. The motor driver unit 22 drives the VCM 15 according to control data (DACOUT) 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. This point will be described later. 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 to which data access is performed from the plurality of head element units 12, and amplifies a reproduction signal reproduced by the selected head element unit 12 with a certain gain (preamplifier). 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 SSW including the TSSW of this embodiment, the AE 13 transfers the servo signal read by the selected head element unit 12 to the R / W channel 21 and writes to all the head element units 12 from the R / W channel 21.・ Transfer data.

  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 read process, the R / W channel 21 extracts data from the read signal supplied from the AE 13 and performs a decoding process. The decoded read data is supplied to the HDC / MPU 23. The R / W channel 21 includes a clock circuit, and timing control is executed according to a clock signal generated by the R / W channel 21.

  In the HDC / MPU 23, the MPU operates according to the microcode loaded in the RAM 24. As the HDD 1 starts up, 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 microcode operating on the MPU. The HDC / MPU 23 performs overall control of the HDD 1 in addition to necessary processing relating to data processing such as positioning control of the head element unit 12 and interface control. The TSSW of this embodiment is executed under the control of the HDC / MPU 23.

  FIG. 2 schematically shows the SSW method including TSSW. The SSW reads the pattern (PO) written on the inner circumference (ID) side or outer circumference (OD) side servo track (TO) with the read element 121 in the head element section 12 while reading the pattern (PO). A new pattern (PN) is written by the write element 122 in the head element unit 12 arranged in the servo track (TN). That is, while the read element 121 follows the servo pattern of each sector of the reference track (TO), the write element 122 writes a new servo pattern PN to the track (TN) after a predetermined timing from the detection of each sector. The servo pattern can be written on the entire surface of the magnetic disk 11 by writing the pattern while sequentially moving the head element portion 12 toward the outer peripheral side or the inner peripheral side.

  In the following description, it is assumed that the read element 121 is arranged closer to the inner periphery (ID) side of the magnetic disk 11 than the write element 122. By writing the pattern from the inner peripheral side, the read element 121 can read the pattern previously written by the write element 122. Thus, the write element 122 can write a new pattern while aligning the head element unit 12 with the pattern read by the read element 121. Note that the TSSW of this embodiment can be started from the outside of the magnetic disk 11 by changing the positions of the read / write elements 121 and 122. In the TSSW of this embodiment, the position of each element in the circumferential direction is not particularly limited.

  Further, FIG. 2 shows some values defined by the read element 121 and the write element 122. One is the write width (W_Width) which is the width of the write element 122, and the other is the read width (R_Width) which is the width of the read element 121. Further, a read / write offset (RW_Offset) is defined. The read / write offset is a distance in the radial direction between the read element 121 and the write element 122. Specifically, it is the distance in the radial direction of the magnetic disk 11 between the centers of the read element 121 and the write element 122. The read / write offset varies depending on the position of the head element portion 12 in the radial direction. In the head element unit 12, there is a read / write offset even at the track position closest to the OD side. As a result, the servo pattern written on the inner circumference side is read out, the head element unit 12 is aligned, and the servo pattern can be written up to the track on the most OD side.

  Here, the pattern format of the servo pattern will be described with reference to FIG. FIG. 3A shows the format of one servo pattern (Product Servo Pattern that is finally written on the magnetic disk). The servo pattern is composed of a preamble, a servo address mark (SAM), a track ID (Gray) composed of a gray code, a servo sector number (PHSN), and a burst pattern (Burst). It is configured.

  When the servo gate of the R / W channel 21 is opened in the Preamble, the servo read clock is synchronized with this preamble, and the amplitude of the VGA (Variable Gain Amplifier) of the R / W channel 21 is set to the expected value. adjust. The SAM is a portion indicating that actual information such as Gray is started, and has an accurate correlation with the position where the SAM signal, which is a timing signal that is normally output when the SAM is found, is written on the magnetic disk 11. The track ID is information indicating a track number (Cylinder number) and is a Gray Code that changes for each track in the radial direction, and the servo sector number (PHSN) is the order of servo sectors counted from the Index.

  Here, Index is a signal generated by the motor driver unit 22 that drives the spindle motor 14 in accordance with the back electromotive force of the spindle motor 14 and is defined by the rotation period of the spindle motor 14.

  The burst pattern (Burst) is a signal indicating a more precise position of the track indicated by the track ID. In this example, A, B, C written in a zigzag pattern at a slightly different position on the track for each track. , D have four amplitude signals. The A and B sets and the C and D sets are in a positional relationship shifted from each other by a half track pitch. Each of these Burst A, B, C, and D is a single frequency signal having the same cycle as the preamble (Preamble).

  FIG. 3B shows a servo pattern written over a plurality of continuous servo tracks, specifically, 10 servo tracks. Here, the servo track pitch is half of the data track pitch in which user data is stored, and FIG. 3B corresponds to 5 data tracks. In the TSSW of this example, half of the pattern on the outer peripheral side is overlapped with half of the pattern written on the inner peripheral side, and the servo pattern is written from the inner peripheral side to the outer peripheral side.

  In this way, SSW including TSSW refers to a pattern written by itself, and uses temporal and spatial information obtained from the signal to make temporal (timing control in the circumferential direction) and spatial (in the radial direction). This is a method of writing the next pattern at a position shifted in the radial direction by the read / write offset while performing position control. However, at the beginning of the TSSW process, there is no signal written on the magnetic disk 11, and it is impossible to write the next pattern with reference to some pattern.

  Normally, in the TSSW, a sufficient current is first supplied to the VCM 15 so that the actuator 16 is abutted against a crash stop (not shown) and the position of the head element portion 12 in the radial direction is kept stable. Here, the crash stop is a member that restricts movement in the rotation direction by colliding with the actuator 16, and is arranged on both the inner peripheral side and the outer peripheral side with respect to the actuator. Typically, the crash stop is made of resin. In order to change the position of the head element unit 12 with the actuator 16 applied to the crash stop, the value of the VCM 15 current is finely adjusted.

  As understood from the pattern of FIG. 3B, the TSSW writes the servo pattern using the characteristics of the head element unit 12. Therefore, it is important to accurately determine the characteristic value of the head element unit 12 in the initial procedure of TSSW. Specifically, the characteristic values include a write width (W_Width) and a read / write offset (RW_Offset) (see FIG. 2 respectively). The track pitch is determined by the write width (W_Width), and the read / write offset (RW_Offset) defines the distance between the read track and the write track. Also, it is necessary to determine the actual track pitch from the measured write width (W_Width). Since the characteristic value of the head element unit 12 is different for each HDD, it is necessary to measure for each HDD.

  As described above, in the initial procedure of the TSSW of this embodiment, the actuator 16 is pressed against the crash stop. Therefore, each of the write width (W_Width), track pitch, and read / write offset (RW_Offset) can be defined by the VCM current applied to the VCM 15. Similarly, the control data of the VCM current can be represented by DACOUT given from the HDC / MPU 23 to the motor driver unit 24. That is, DACOUT is a position control signal that defines the position of the head element unit 12, that is, the read element 121.

  The TSSW of this embodiment writes a plurality of specific patterns on the magnetic disk 11 by the head element unit 12 and measures the head characteristics. Further, the measured values are used to determine parameter values required for TSSW such as track pitch. Each of the plurality of patterns is the same type of pattern, and is a pattern composed of the same frequency signal as the Burst used in the Product Servo Pattern. In the following description, this pattern is referred to as an initial burst pattern (IB pattern).

  FIG. 4 shows a part of a plurality of IB patterns written on the magnetic disk 11, and specifically shows six IB patterns from the innermost periphery. As described above, each IB pattern can be a periodic pattern having a length BL at the same frequency as the Burst frequency used in the Product Servo Pattern. The length BL must be sufficiently longer than the period in which the servo gate normally used by the HDD 1 is active (period in which the servo gate is open). Here, the servo gate is a control signal for reading servo data (Product Servo Pattern) from the magnetic disk 11, and is given to the R / W channel 21 by the HDC / MPU 23. In normal servo control of the HDD 1, servo data is read from the magnetic disk 11 and transferred to the HDC / MPU 23 while the servo gate is active.

  The HDD 1 reads each IB pattern while writing the IB pattern from the inner circumference side. Here, an example in which an IB pattern of 6 slots from SLOT 0 to SLOT 5 is written on the magnetic disk 11 will be described. Each slot is composed of a plurality of IB patterns (six IB patterns from IBn_0 to IBn_5 in the figure) having the same circumferential position. The slots are separated by a certain distance in the circumferential direction, and are represented by Tsect (time) in this example. This Tsect is the same as or different from the sector interval of the Product Servo Pattern. The IB patterns adjacent in the radial direction, for example, the IB pattern (IB0_0) and the IB pattern (IB0_1) are formed so as to overlap in the radial direction.

  First, the actuator 16 is pressed against the crash stop with the DACOUT value Iact [0], and the IB pattern (IB0_0) is written after the time S0 determined from the index. Next, at the DACOUT value Iact [0], the read element 121 reads the amplitude of the written IB pattern (IB0_0). Thereafter, the DACOUT value is decreased by r_Step, the position of the head element unit 12 (read element 121) is slightly shifted to the outer peripheral side, and the Burst signal of the IB pattern is read. Thereafter, the Burst signal of the IB pattern is read at each DACOUT value while sequentially changing the DACOUT value in units of r_Step.

  This process is repeated, and the next IB pattern (IB0_1) from the index to the position of S0 + Tsect at the Kth operation, that is, Iact [K] = Iact [0] −K * r_Step (K * r_Step = w_Step). ) With a length BL. Further, at that position, the amplitude of the IB pattern is read in the round following the writing. Thus, by writing and reading six IB patterns, a profile as shown in FIG. 5 can be obtained.

  In other words, FIG. 5 is a schematic diagram showing the profile 200 with the horizontal axis representing the shift amount of the read element 121 in the radial direction and the vertical axis representing the signal amplitude. Here, the shift amount of the read element 121 in the radial direction is a change in the DACOUT value. That is, the profile indicates the relationship of the amplitude value of each burst pattern to the DACOUT value that is the position control signal value. Such a profile may be obtained by averaging six IB patterns for each head element unit 12 as in the present embodiment, but may be one or more measurements. Further, as described above, one IB pattern may be recorded and reproduced to obtain a profile, or after a plurality of IB patterns are written once, the head element unit 12 is moved to the first on the inner peripheral side. It is also possible to return to the position and measure the profile at r_Step intervals.

  In this profile 200, the maximum value on the vertical axis can be measured as the amplitude AP, and the width above the minimum value (= 0) and half of the maximum value 1 / 2AP (50% of the maximum value) can be measured as the write width W_Width. In the present embodiment, the amplitude AP and the write width W_Width are obtained for each head element unit 12 from the average profile of six profiles. Note that six amplitudes AP and write width W_Width may be obtained from each profile, and the average value thereof may be obtained.

  Next, a method for selecting a propagation head using parameters of the amplitude AP and the write width W_Width will be described. In this embodiment, the propagation head that is normally selected as having the largest write width is selected in consideration of the amplitude value in addition to the write width. Specifically, one having the largest write width among those having an amplitude equal to or greater than a predetermined threshold Ath is selected as the propagation head.

  Here, this threshold value Ath can be determined as follows, for example. That is, a graph with the horizontal axis representing the amplitude data obtained from the current production and the vertical axis representing the product yield at that time is created, and a value that can reduce the number of defective products to less than a predetermined number is set as the amplitude threshold Ath. . By setting the amplitude to be equal to or greater than the predetermined threshold value Ath, it is possible to prevent selection of a write element 122 having a low writing performance or a read element 121 having a low reading performance, thereby improving the yield. Thus, it is possible to prevent the servo pattern reading performance from being deteriorated due to the servo pattern deviation that is likely to occur on the outer peripheral side, and as a result, the servo data can be accurately recorded. Further, by selecting one having a large write width, it is possible to avoid squeeze as much as possible.

A method for selecting a propagation head will be specifically described. Assume that the HDD has two head element units H [0] and H [1], the write widths are W [0] and W [1], and the amplitudes are A [0] and A [1]. I will do it. In this case, “propagation head whose amplitude is equal to or greater than a predetermined threshold Ath and whose write width is maximum” is selected. Here, when the amplitude is smaller than the threshold value Ath in any of the head element portions, a wider one is desirable for writing the timing pattern and the servo pattern, so that one having a larger write width is selected. When the propagation head is selected by applying the above, it becomes as shown in Table 1 below.

  That is, as shown in Table 1, in the head [0] and the head [1], when the write width W [0] ≧ W [1], the amplitude A [0] of the head [0] is larger than the threshold value Ath. In this case, or if any head is smaller than the threshold Ath, the head [0] is selected. If only the amplitude A [1] of the head [1] is larger than the threshold Ath, the head [1] is selected. If the write width W [0] <W [1], the head [1] is selected if the amplitude A [1] of the head [1] is larger than the threshold value Ath or if any head is smaller than the threshold value Ath. When only the amplitude A [0] of the head [0] is larger than the threshold value Ath, the head [0] is selected.

  The same applies even when there are two or more head element portions. Of the two or more head element units, only those having the amplitude of the threshold value Ath are extracted, and the one having the largest write width is set as the propagation head. When the amplitude of any head element portion is smaller than the threshold value Ath, the head element portion having the largest amplitude is set as a propagation head.

  A propagation head is selected based on the amplitude AP and the write width W_Width by the HDC / MPU 23 that executes a test program (SSWCode) for executing SSW, and read by the read element 121 of the selected head element 12. A predetermined value is set in the corresponding register of the AE 13 so that is executed. Thus, the servo pattern is written by the write element 122 while the servo pattern is reproduced by the read element 121 of the propagation head, thereby writing the servo pattern by SSW on the entire surface of the disk.

  Next, the effect in this Embodiment is demonstrated. In the write test performed after writing the servo pattern, only the HDD in which a write error considered to be related to writing of the servo pattern has occurred is extracted, and the results of retrying from the servo pattern writing process again after applying the present invention are as follows: Shown in the table.

  By applying the present invention, as shown in the result 1 of Table 2 above, the write error is reduced to about 70% in the HDD that was originally defective with 100% write error. And 20% of HDDs passed the final inspection. Further, Table 2 shows the result 2 in which the HDDs whose propagation heads have been changed by applying the present invention are used as a population. As shown in Table 2, the write error was reduced to about 50%, and about 40% passed the final inspection. As is apparent from this, when selecting the propagation head, not only the write width but also the amplitude parameter can be taken into consideration, and a dramatic improvement in yield can be realized.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the TSSW has been described as an example, but it is needless to say that the present invention can also be applied when selecting an SSW propagation head. By considering not only the read width but also the amplitude, it is possible to select a head that considers not only the write element but also the read element performance, improving servo pattern read performance and dramatically increasing the HDD manufacturing yield. Can be improved.

It is a block diagram which shows the structure of the whole hard disk drive concerning embodiment of this invention. It is a figure which shows roughly the technique of TSSW of HDD concerning embodiment of this invention. It is a figure which shows the format of the servo pattern of HDD concerning embodiment of this invention. It is a figure which shows a part of multiple IB pattern written in the magnetic disc of HDD concerning embodiment of this invention. It is a figure for demonstrating the parameter used when selecting the propagation head in TSSW of HDD concerning embodiment of this invention.

Explanation of symbols

10 enclosure,
11 Magnetic disk,
12 Head element part,
14 spindle motor,
15 voice coil motor,
16 Actuator,
20 circuit board,
21 read / write channel,
22 Motor driver unit,
23 Hard disk controller / MPU,
51 hosts,
121 lead element,
122 Light element

Claims (10)

A servo pattern recording method for positioning control of a head in a disk device having a disk, a recording element for recording a pattern on the disk, and a plurality of heads provided with a reproducing element for reading the pattern recorded on the disk There,
Based on the result of recording a predetermined pattern by the recording element of each head and reading the pattern by the reproducing element, the writing width of the recording element of each head and the amplitude of the read pattern are calculated,
Select one head based on the write width and amplitude values,
A servo pattern recording method in which each head is positioned and controlled while the previously recorded servo pattern is reproduced by the reproduction element of the selected head, and the servo pattern is sequentially recorded by the recording element of each head. 2. The servo pattern recording method according to claim 1, wherein when the head is selected, the one having the largest writing width among those having the amplitude equal to or greater than a predetermined amplitude threshold is selected. 3. The servo pattern recording method according to claim 2, wherein when all of the amplitudes obtained from the plurality of heads are less than the predetermined threshold value, the one having the largest amplitude is selected. The servo pattern recording method according to claim 1, wherein when calculating the write width and amplitude, a plurality of the predetermined patterns are recorded, and an average value obtained by reading the predetermined patterns is obtained. When reading the predetermined pattern, read while shifting the reproduction element at a predetermined interval on the predetermined pattern, creating a profile with the vertical axis representing the amplitude value of the read signal with the shift amount as the horizontal axis, The servo pattern recording method according to claim 1, wherein the write width and amplitude are calculated based on the profile. The servo pattern recording method according to claim 5, wherein the maximum amplitude value obtained by the profile is the amplitude, and the width of the profile at a position ½ of the amplitude is the write width. A plurality of heads each including a disk, a recording element that records a pattern on the disk, and a reproducing element that reads a pattern recorded on the disk are stored in a housing.
A control circuit for controlling writing and reproduction of the plurality of heads is mounted,
A method of manufacturing a disk device for recording a servo pattern for controlling the positioning of the plurality of heads on the disk by the plurality of heads,
When recording the servo pattern,
A predetermined pattern is recorded by the recording element of each head, and based on the result of reading the pattern by the reproducing element, the write width of the recording element of each head and the amplitude of the read pattern are calculated,
Select one head based on the write width and amplitude values,
A method of manufacturing a disk device, wherein each head is positioned and controlled while a previously recorded servo pattern is reproduced by the reproducing element of the selected head, and the servo pattern is sequentially recorded by the recording element of each head. 8. The method of manufacturing a disk device according to claim 7, wherein when the head is selected, the one having the largest write width among those having the amplitude equal to or greater than a predetermined amplitude threshold is selected. A disk device having a disk, a recording element for recording a pattern on the disk, and a plurality of heads provided with a reproducing element for reading the pattern recorded on the disk, and recording a servo pattern on the disk by its own head There,
The recording element for recording a predetermined pattern;
The reproducing element for reading the pattern;
A head selection unit that calculates the write width of the recording element of each head and the amplitude of the read pattern based on the pattern reading result of the reproducing element, and selects one head based on the calculation result;
A control unit that controls the positioning of each head while reproducing the servo pattern recorded earlier by the reproducing element of one head selected by the head selecting unit, and sequentially records the servo pattern by the recording element of each head. And a disk device. The disk device according to claim 9, wherein the head selection unit selects the one having the largest writing width among those having the amplitude equal to or greater than a predetermined amplitude threshold value.

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