JP2007287247A - Method for writing pattern in recording surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a track pitch of a servo pattern from being greatly fluctuated in self-servo light. <P>SOLUTION: In one embodiment of this invention, a servo light controller carries out a predetermined sequence so that a pre-amplifier IC 13 increases in heat generation after a calibration sequence in self-servo light of HDA 1. After that, the servo light controller starts pattern write sequence to a magnetic disk 11. Thus, a large variation in the track pitch of the servo pattern written before and after the calibration sequence is suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of writing a pattern on a recording surface of a disk, and more particularly to a method of positioning a head while reading a pattern written on the recording surface by a head and writing a new pattern on the recording surface.

  2. Description of the Related Art As disk drive devices, devices that use recording disks of various modes such as optical disks, magneto-optical disks, and flexible magnetic disks 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. In addition to computer systems, HDD applications 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. Yes.

  A magnetic disk used in the HDD has a plurality of data tracks and servo tracks formed concentrically. The servo track has a plurality of servo data (servo patterns) separated in the circumferential direction. User data is recorded between the servo sectors. When the head element unit as a thin film element accesses a desired area (address) according to the servo data, user data can be written or user data can be read.

  Each servo pattern (referred to as a product servo pattern in this specification) includes 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.

  As described above, the product servo pattern is formed with a plurality of sectors spaced apart in the circumferential direction in each track. The product servo patterns that are at the same position in the circumferential direction, that is, having the same sector number, have the same position (phase) in the circumferential direction over all tracks. The product servo pattern is written on the magnetic disk in the factory before the HDD as a product is shipped. Conventional typical product servo pattern writing is performed using a servo writer as an external device. The HDD is set in the servo writer, the servo track writer positions the head in the HDD with a positioner (external positioning mechanism), and writes the product servo pattern generated by the product servo pattern generation circuit to the magnetic disk .

  Currently, a product servo pattern writing process (hereinafter referred to as a servo writing process) occupies a major position in the manufacturing cost of HDDs. In particular, in recent years, competition for increasing the capacity of HDDs has intensified, and TPI (Track Per Inch) has been increasing accordingly. As TPI increases, the number of tracks increases and the track width (track pitch) decreases. These increase the servo write time and increase the precision of the servo writer. It has become. In order to reduce this cost, efforts are being made to reduce the cost of servo writers and servo write time.

  SSW (Self Servo Write) has been proposed as one method for solving the above problem. Unlike conventional servo write, SSW uses only the mechanical mechanism of the HDD body, and controls the spindle motor (SPM) and voice coil motor (VCM) in the HDD from an external circuit. Use to write the product servo pattern. As a result, the cost of the servo writer is reduced.

  The SSW is a pattern that has already been written on the inner peripheral side or the outer peripheral side by utilizing the fact that the read element and the write element in the head element portion have different radial positions (referred to as read / write offset in this specification). The head element portion is positioned while the read element reads, and the write element writes a new pattern on a desired track away from the read / write / offset. In addition to the product servo pattern, the SSW writes other patterns on the recording surface and uses them to execute head position control and timing control.

Typically, the HDD has a plurality of recording surfaces, a plurality of head element portions corresponding to each recording surface, and an actuator that supports the plurality of element portions. The SSW reads a pattern on the recording surface using one head element unit (referred to as a propagation head in this specification) selected from a plurality of head element units, and outputs a signal of the read pattern. The head elements are positioned by controlling the actuator by using the actuator. In the positioned state, a pattern is simultaneously written on each recording surface by all head element portions. Here, Patent Document 1 discloses a servo track writer for writing on each recording surface of a plurality of magnetic disks by shifting the servo write track in accordance with the positional deviation of the head.
JP 2004-199841 A

  The SSW has a calibration sequence in addition to a sequence for writing servo data in each servo write track while sequentially moving and positioning the head element portion. In the calibration sequence, servo gain adjustment for accurately positioning the head element portion at a desired position, confirmation that a pattern is written at a pitch according to the design, and the like are performed. Unlike the pattern writing sequence, this calibration sequence does not perform pattern writing and continues the pattern reading process.

  The SSW executes a calibration sequence when the pattern writing sequence to a partial area of the recording surface is completed. After the end of the calibration sequence, the SSW restarts the pattern writing sequence in an area that is continuous with the area where writing has been completed previously. The inventors have recognized that a servo track pitch shift occurs at the boundary between the two areas on the recording surface other than the recording surface corresponding to the propagation head. This was found to be due to a temperature drop in the enclosure due to the calibration sequence.

  One embodiment of the present invention uses a plurality of heads in a housing, an actuator that supports and moves the plurality of heads in the housing, and a circuit element that is mounted in the housing and outputs a signal to the plurality of heads. In this method, a pattern is written on each of a plurality of recording surfaces rotating in the housing. In this method, in the first sequence, a pattern on a corresponding recording surface is read by one propagation head in the plurality of heads, the plurality of heads are positioned by the actuator, and the plurality of recording surfaces are positioned. Then, a new pattern is written by the plurality of heads, and the positioning and the writing of the new pattern are repeated, and the patterns are sequentially written at different positions in the radial direction on each recording surface. Further, after the first sequence, a second sequence in which the heat generation state of the circuit element is lower than the first sequence is executed. Before newly writing a pattern adjacent to the pattern written in the first sequence, the circuit element is operated in a heat generation state higher than that in the second sequence, and then the adjacent pattern is written. By operating the circuit element in a heat generation state higher than that in the second sequence, it is possible to suppress the pitch variation of the pattern adjacent to the pattern in the first sequence.

  The present invention is effective when the second sequence continuously repeats reading by at least one of the plurality of heads. Preferably, the heat generation of the circuit element is made higher than that in the second sequence by performing writing on the corresponding recording surface by at least one of the plurality of heads. As a result, the heat generation of the circuit elements can be increased effectively and quickly. Further, it is preferable that writing is performed on the corresponding recording surface by a head other than the propagation head. Alternatively, it is preferable that writing is performed on the corresponding recording surface by the propagation head, and the area to be written is an area other than an area in which a pattern used for positioning of the propagation head is written. This can prevent adverse effects on the reading of the propagation head.

  Preferably, after the heat generation of the circuit element is made higher than that in the second sequence, the pattern is read by a head different from the propagation head in a state where the pattern is read and positioned by the propagation head, Check the deviation of the head from the target position. As a result, the pitch variation of the pattern can be prevented more reliably. Furthermore, it is preferable that the propagation head and the different heads alternately read out patterns from the corresponding recording surfaces. As a result, the deviation can be accurately measured.

  Another aspect of the present invention uses a plurality of heads in a housing, an actuator that supports and moves the plurality of heads in the housing, and a circuit element that is mounted in the housing and outputs a signal to the plurality of heads. The method of writing a pattern on each of a plurality of recording surfaces rotating in the housing. In this method, a pattern is written on each recording surface by the plurality of heads. Further, the pattern on the corresponding recording surface is read out by one of the plurality of heads, and the plurality of heads are moved by the actuator. Then, a new pattern is written by the plurality of heads in a state in which the inside of the housing is temperature-controlled by heating and positioning is performed using a read signal of the propagation head. By writing a new pattern with a plurality of heads in a state in which the temperature inside the housing is controlled, variation in the pitch of the pattern can be suppressed.

  Preferably, the temperature in the casing is adjusted by increasing the amount of heat generated by the circuit elements mounted in the casing and outputting signals to the plurality of heads. Further, it is preferable that the heat generation amount of the circuit element is increased by writing an erase pattern on the corresponding recording surface by at least one of the plurality of heads.

  Another aspect of the present invention uses a plurality of heads in a housing, an actuator that supports and moves the plurality of heads in the housing, and a circuit element that is mounted in the housing and outputs a signal to the plurality of heads. The method of writing a pattern on each of a plurality of recording surfaces rotating in the housing. In the first sequence, a pattern on the corresponding recording surface is read by one of the plurality of heads, the plurality of heads are positioned by the actuator, and a new state is determined by the plurality of heads on the plurality of recording surfaces in a determined state. A pattern is written, and the positioning and the writing of a new pattern are repeated, and the pattern is sequentially written at each radial position on each recording surface. After the first sequence, a calibration sequence for controlling the actuator is executed. Before newly writing a pattern adjacent to the pattern written in the first sequence, writing is performed on the corresponding recording surface by at least one of the plurality of heads, and then the adjacent pattern is written. Thereby, the pitch fluctuation of the pattern adjacent to the pattern of the first sequence can be suppressed.

  According to the present invention, it is possible to suppress variations in track pitch in writing a pattern on a recording surface.

  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. Hereinafter, preferred embodiments of the present invention will be described by taking servo write of a hard disk drive (HDD) as an example of a disk drive device as an example. The servo write of this embodiment is a self-servo write (SSW) for writing a servo pattern by controlling the internal mechanism of the HDD main body. The SSW in this embodiment performs a predetermined sequence after the calibration sequence so that the heat generation of the preamplifier IC increases. Thereafter, a pattern writing sequence on the recording surface is started. As a result, the track pitch of the pattern written before and after the calibration sequence is prevented from greatly fluctuating.

  Servo writing in this embodiment will be described below. FIG. 1 is a block diagram schematically showing a logical configuration of the servo write control device 2 that controls the servo write of HDA 1 and HDA 1. The HDA 1 is a component of the HDD and includes a housing 10 having a base and a top cover that closes an upper opening of the base. The HDA 1 includes a magnetic disk 11, a head slider 12, a preamplifier IC 13, which is an example of a circuit element, a voice coil motor (VCM) 15, and an actuator 16. The actuator 16 supports the head slider 12 at the tip. Further, the preamplifier IC 13 is fixed to the actuator 16 via a circuit board (not shown), and specifically, is fixed near the rotating shaft 165.

  The HDD includes a circuit board fixed to the outside of the housing 10 in addition to the HDA 1. An IC that performs signal processing and control processing is mounted on the circuit board. The servo write of this embodiment does not use the circuit on the control circuit board, and the servo write control device 2 controls the servo write. The servo write of this embodiment directly writes the servo data (servo pattern) on the magnetic disk 11 by directly controlling the internal mechanism of the HDA 1. The magnetic disk 11 is a non-volatile storage disk that stores data by magnetizing a magnetic layer.

  Such servo write is called self-servo write (SSW). The SSW writes servo data used for writing and reading user data to the magnetic disk 11 using each component in the housing 10. Hereinafter, this servo data is referred to as a product servo pattern. Note that the servo write of this embodiment can also be executed using a control circuit mounted on the HDD.

  The servo / write control device 2 controls and executes the SSW of this embodiment. The servo / write control device 2 has an SSW controller 22. The SSW controller 22 controls the entire SSW. The SSW controller 22 executes positioning control of the head slider 12 and pattern generation control. The SSW controller 22 can be configured by a processor that operates in accordance with a pre-stored microcode. The SSW controller 22 executes control processing in response to a request from an external information processing apparatus, and transmits necessary information such as error information to the information processing apparatus.

  In writing a pattern to the magnetic disk 11, the SSW controller 22 instructs the pattern generator 21, and the pattern generator 21 generates a predetermined pattern. The read / write interface 23 converts the pattern generated by the pattern generator 21 and transfers the pattern signal to the preamplifier IC 13. The preamplifier IC 13 amplifies the signal and transfers it to the head slider 12, and the head slider 12 writes a pattern on the magnetic disk 11.

  The SSW controller 22 controls the actuator 16 using a signal read by the head slider 12 to move and position the head slider 12. Specifically, the signal read by the head slider 12 is input to the amplitude demodulator 27 via the RW interface 23. The read signal demodulated by the amplitude demodulator 27 is AD converted by the AD converter 26 and input to the SSW controller 22. The SSW controller 22 analyzes the obtained digital signal and calculates a numerical control signal.

  The SSW controller 22 sends the value to the DA converter 25. The DA converter 25 DA-converts the acquired data and provides a control signal to the VCM driver 24. The VCM driver 24 supplies a control current to the VCM 15 based on the control signal, and moves and positions the head slider 12. In the present specification, a device including components other than the servo write control device 2 and the magnetic disk 11 of the HDA 1 is referred to as a self servo track writer (SSTW). That is, the SSTW writes a servo pattern on the recording surface of the magnetic disk 11.

  As shown in FIG. 2, the HDA 1 of the present embodiment has a plurality of magnetic disks 11 a-11 c, and each magnetic disk 11 a-11 c is fixed to the rotation shaft of a spindle motor (SPM) 14. The SPM 14 rotates the magnetic disks 11a-11c fixed thereto at a predetermined angular velocity. Further, both surfaces of each magnetic disk 11a-11c are recording surfaces, and the HDA 1 has a plurality of head sliders 12a-12f corresponding to the respective recording surfaces.

  Each head slider 12 a-12 f is fixed to the actuator 16. Specifically, the actuator arm 162a supports the head slider 12a, the actuator arm 162b supports the head sliders 12b and c, the actuator arm 162c supports the head sliders 12d and e, The arm 162d supports the head slider 12f.

  The actuator 16 is connected to the VCM 15 and rotates about the rotation shaft 165 to move the head sliders 12a-12f in the radial direction on the recording surfaces of the magnetic disks 11a-11c. Each head slider 12a-12f has a slider and a head element portion (not shown) as a thin film element formed thereon. The head element unit includes a write element that converts an electric signal into a magnetic field according to write data and a read element that converts a magnetic field from the magnetic disk 11 into an electric signal.

  The preamplifier IC 13 selects one head slider that reads data from the plurality of head sliders 12a to 12f, amplifies (preamplifies) a reproduction signal reproduced by the selected head slider with a certain gain, Output to servo / write controller 2. The preamplifier IC 13 amplifies the signal from the servo / write control device 2 and outputs the amplified signal to the selected head slider. Typically, in writing a product servo pattern, all the head sliders 12a-12f are selected simultaneously.

  Returning to FIG. 1, a plurality of servo areas 111 extending radially from the center of the magnetic disk 11 and formed at predetermined angles are formed on the recording surface of the magnetic disk 11 by SSW. FIG. 1 illustrates seven servo areas. In each servo area 111, a product servo pattern for controlling the positioning of the head slider in reading / writing user data is recorded. An area between two adjacent servo areas 111 is a data area 112 in which user data is recorded. The servo areas 111 and the data areas 112 are alternately provided at a predetermined angle.

  FIG. 3 shows the data format of the product servo pattern 115 of one servo sector. In one servo area 111, a product servo pattern 115 of one servo sector is formed in the circumferential direction, and a product servo pattern 115 of a plurality of servo sectors is formed in the radial direction. The product servo pattern 115 includes a preamble (PREAMBLE), a servo address mark (SAM), a track ID (GRAY) including a gray code, a servo sector number (PHSN) (optional), and a burst pattern (BURST). ). The SAM is a portion indicating that actual information such as a track ID starts, and has a precise 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 burst pattern (BURST) is a signal indicating a more precise position of the servo track indicated by the track ID. The burst pattern typically includes four amplitude signals A, B, C, and D written in a zigzag pattern at slightly different positions on the circumference for each servo track (see FIG. 5). . Each of these bursts is a single frequency signal having the same period as the preamble (PREAMBLE).

  FIG. 4 schematically shows a pattern written on the recording surface by the SSTW of this embodiment and a writing method thereof. FIG. 4 shows a pattern corresponding to one servo sector. In addition to the product servo pattern 115, the SSTW writes a timing pattern 116 and a radial pattern 117. The timing pattern 116 is a pulse pattern, and the radial pattern 117 is a burst of a predetermined frequency. Accordingly, one sector in the SSW of this embodiment has an area 151 for writing the product servo pattern 115, an area 161 for writing the timing pattern 116 for 1 slot, and an area 171 for writing the radial pattern 117 for 1 slot. Yes. The timing pattern 116 and the radial pattern 117 are written in the data area 112 that stores user data.

  The SSTW refers to the pattern written on the magnetic disk 11 by itself, and uses temporal and spatial information obtained from the signal, and uses the temporal and spatial information of the head element unit 120 (timing control in the circumferential direction) and spatial ( The next pattern is written at a position shifted in the radial direction by the read / write offset while performing control (position control in the radial direction).

  The read / write offset (RWO) is a radial distance between the write element 121 and the read element in the head element unit 120, specifically, between the centers of the read element 122 and the write element 121. The distance in the radial direction of the magnetic disk 11. The read / write offset varies depending on the radial position on the magnetic disk 11. Note that the positions of the write element 121 and the read element 122 are also shifted in the circumferential direction, and the interval in this direction is referred to as read / write separation.

  The SSTW of this embodiment selects one from a plurality of head element portions (for example, the head element portion of the head slider 12b in FIG. 2), and reads the pattern on the recording surface by the selected head element portion. This head element portion is referred to as a propagation head in this specification. Then, the SSTW controls the actuator 16 using the signal read by the propagation head, and simultaneously writes each pattern on each recording surface by all the head sliders 12a-12f.

  In this embodiment, as shown in FIG. 4, the read element 122 is arranged closer to the inner periphery (ID) side of the magnetic disk 11 than the write element 121. The pattern is written from the inner circumference side to the outer circumference side. By writing the pattern from the inner peripheral side, the read element 122 can read the pattern previously written by the write element 121. As a result, the write element 121 can write a new pattern while aligning the head element unit 120 with the pattern read by the read element 122. Note that the SSW can be started from the outside of the magnetic disk 11 by changing the positions of the write element 121 and the lead 122.

  Specifically, the SSTW uses the radial pattern 117 to position the head element unit 120 and measures the pattern writing timing using the timing pattern 116 as a reference. After elapse of a predetermined time from the timing when the read element 122 of the propagation head reads the timing pattern, the write element 121 of each head element unit 120 writes (part of) the product servo pattern 115. The timing pattern 116 of the next sector is written on the basis of the reading of the timing pattern 116 of the previous sector.

  As shown in FIG. 4, the write element 121 writes each product servo pattern 115 so as to partially overlap in the radial direction. That is, in the formation of each product servo pattern, a part of each pattern is overwritten with the pattern on the outer peripheral side. In FIG. 5, four already written product servo patterns 115 are shown, and the write element 121 is in the process of forming the fifth product servo pattern from the inner peripheral side.

  The write element 121 writes half of the product servo pattern in one round of the magnetic disk. In this specification, a track corresponding to half of the product servo pattern is called a servo write track. The track of the product servo pattern is called a servo track. The track pitch of the servo write track is half of the servo track pitch. In the example of FIG. 4, seven servo write tracks have already been written, and the write element 121 is in the middle of writing the eighth servo write track from the inner circumference side.

  Timing patterns 116 in the same sector are formed at substantially the same position in the circumferential direction. On the other hand, each radial pattern 117 is formed at a different circumferential position from the radial pattern 117 adjacent in the radial direction. That is, each adjacent radial pattern 117 is displaced in the circumferential direction. Further, in the radial direction, the adjacent radial patterns 117 are formed so as to overlap each other. In FIG. 4, each radial pattern 117 is sequentially shifted to the right side of the drawing as it goes in the outer circumferential direction, but is further written at a position shifted to the left side of the drawing in the outer track.

  The SSW controller 22 performs head positioning using the read signal of the radial pattern 117. Specifically, an example in which the read element 122 is positioned at the target position 118 will be described with reference to FIG. The radial dimension of the read element 122 in FIG. 5 corresponds to the read width, and the dimension of the write element 121 corresponds to the write width. The magnetic disk 11 rotates from right to left in the figure, and the read element 122 moves from left to right in the figure. The write element 121 writes a corresponding servo write track at the target position 119.

  In order to position the write element 121 at the target position 119, the SSW controller 22 positions the read element 122 from the target position 119 to the target position 118 on the inner side of the read / write offset (RWO). The read element 122 reads the radial patterns 117a, 117b, and 117c. The SSW controller 22 calculates a function value (referred to as a PES value in this specification) of the amplitude (A, B, and C) of each of the radial patterns 117a, 117b, and 117c so that the value becomes a target value. The read element 122 is positioned.

  With the read element 122 positioned at the target position 118, the write element 122 writes the radial pattern 117d. In each pattern writing step, typically, the target position of the read element 122 does not coincide with the center of each radial pattern 117 and is shifted in the radial direction.

  The SSW controller 22 of this embodiment sequentially moves the head sliders 12a to 12f so that a value called APC matches a predetermined value. As a result, a product servo pattern having a desired pitch is written. The SSTW determines the target PES value so that the APC matches (approaches) the specified value, and writes the pattern in each servo write track with the propagation head positioned at the target position.

  APC is calculated from the read amplitudes A, B and C of the radial pattern 117 of three adjacent servo write tracks. Specifically, in the state where the propagation head is positioned at the center of one radial pattern 117, the read amplitudes A, B, and C of each radial pattern 117 are acquired. APC is calculated by (A + C / B).

  The target reference APC is preset for each servo track write. As illustrated in FIG. 6, the reference APC is not constant, but varies according to the servo write track. By writing the pattern of each servo write track using this reference APC as a target, the servo write track pitch is controlled to a desired value. The reference APC is determined in advance at the development stage. Specifically, it can be determined by writing an ideal pattern in the HDA of the same design using a rotary positioner and measuring the APC of the pattern.

  As described above, the SSW sequentially writes patterns to each servo write track from the inner circumference side. The SSW according to this embodiment executes calibration when a pattern having a predetermined number of servo write tracks is written. That is, the SSW of this embodiment has a plurality of sequences, and a pattern writing sequence for sequentially writing patterns on each servo write track on the recording surface and a calibration sequence executed between each pattern writing sequence. Has a sequence.

  There are two calibration sequences. One is to write a pattern at a pitch according to the design, so that the APC of the written pattern is measured and a PES value to be a target in subsequent pattern writing is determined. The other calibration sequence adjusts the servo gain for positioning the head slider 12 according to the PES value. The APC calibration sequence is performed once every several hundred servo write tracks. On the other hand, the servo gain calibration sequence is performed once every several thousand servo write tracks.

  It has been found that the track pitch changes greatly in the pattern writing immediately after this calibration sequence is executed. Specifically, the servo write track pitch changes greatly on the recording surface corresponding to the head element unit 120 other than the propagation head. This track pitch change will be specifically described with reference to FIG.

  The read element position 122 a is a position where the read element 122 is positioned at the target position 118. The read element is positioned at the target position 118a using the read amplitude of the radial pattern 117a-117c or a part thereof. That is, in the servo write track 119a, the write element 121 at the write element position 121a writes the radial pattern 117d.

  When pattern writing at the target position 118a (servo write track 119a) is completed, the SSW executes a calibration sequence. After completion of the calibration sequence, the read element 122 and the write element 121 move to the read element position 122b and the write element position 121b, respectively. The read element position 122b corresponds to the target position 118b. The write element 121 at the write element position 121b writes the radial pattern 117e in the servo write track 119b.

  In the head slider 12 other than the propagation head, the position of the radial pattern 117e in the radial direction is displaced to the outer peripheral side or the inner peripheral side. This cause is expected to be due to mechanical displacement or tilting of the actuator 16 caused by a change in heat generation of the preamplifier IC 13. As the actuator 16 moves, each head slider 16 tilts relative to the corresponding recording surface accordingly.

  The propagation head is accurately positioned according to the inclination of the actually read signal. However, the inclination of the other head slider 12 does not coincide with the inclination of the propagation head. For this reason, the radial position of the pattern to be written is different from the propagation head. As a result, in each head slider 12 other than the propagation head, it is considered that the servo write track pitch immediately after calibration fluctuates.

  The pattern writing sequence typically repeats the seek process to the target position of the head slider and the pattern writing process at the target position. That is, the reading process (seek) for one rotation of the disk and the writing (pattern writing) for one rotation of the disk are alternately and continuously repeated. On the other hand, in the calibration sequence, the read process is continuously performed and the write process is not performed.

  First, the servo gain calibration sequence will be described. FIG. 8 is a block diagram schematically showing a servo control system in the SSTW. The operation target includes the HDA 1 and the VCM driver 24 shown in FIG. The SSW controller 22 includes a VCM current determination unit 222 that determines a gain factor 221 and a VCM current value for seeking and following. The difference between the current PES from the ADC 26 and the target is input to the gain factor 221.

  In each servo write track, the PES value and the VCM current value (actual physical position) show a non-linear relationship. The gain factor 221 corrects the non-linear relationship between the PES value and the VCM current value so that the VCM current determining unit 222 determines an optimal current value. The relationship between the PES value and the VCM current value varies depending on the radial position. For this reason, the SSW of this embodiment executes a servo gain calibration sequence in order to calibrate the gain value of the gain factor 221.

  Specifically, the SSW controller 22 moves the read element 122 while changing the VCM current value by a certain value in a specific servo write track, and measures the PES at each position. For example, PES is measured at 10 points in one servo write track. Thereby, the relationship (gain) between the PES value and the VCM current in the servo write track is measured. The SSW controller 22 performs this gain measurement in a plurality of servo write tracks, obtains an average value of each gain, and calibrates the servo gain with the gain factor 221.

  The movement of the read element 122 to each measurement position and the measurement of the PES value at each position do not include a write process. Typically, a servo gain calibration sequence requires time on the order of hundreds of disk revolutions. Since the write process is not performed during this sequence, the amount of heat generated by the preamplifier IC 13, its temperature, and the internal temperature of the HDA 1 are greatly reduced. Thereby, it is considered that each head slider 12 is inclined.

  Next, the APC calibration sequence will be described. As described above, the SSW controller 22 of this embodiment sequentially moves the head element unit 120 so that the APC becomes the specified value. However, measuring APC at each movement to the next servo write track requires a lot of time and greatly affects the yield. Therefore, the SSW of this embodiment measures APC for every several hundred servo write tracks, and determines the target PES for the next process according to the measured value.

  In the APC calibration sequence, as shown in FIG. 9, the read element 122 is moved from the target position 118a where the pattern was written last to the inner circumference side, and APC is measured for a plurality of servo write tracks. In the example of FIG. 9, the read element 122 moves from the position where the pattern was written last to the inside of the four servo write tracks, and sequentially moves from the read element position 122c to the read element position 122f. Read the pattern. In the example of FIG. 9, the APC of the servo write track is measured. By measuring APC of a plurality of servo write tracks, erroneous APC due to a measurement error is prevented from being measured.

  The APC measurement includes a seek and a radial pattern reading process, and the above example executes a seek (read) with four rotations of the disk and a radial pattern reading (read) with four rotations of the disk. The preamplifier IC 13 consumes the most power in the write process, and the power consumption in the read process is small. For this reason, the calorific value and temperature of the preamplifier IC 13 are greatly reduced in the calibration sequence in which the read process continues. Thereby, it is considered that each head slider 12 is inclined.

  The change in the PES value of each head slider 12a-12f due to the continuing read process was measured. FIG. 10 shows the measurement results. As the propagation head, the head slider 12b in FIG. 2 was selected. Hd0, Hd2, Hd3, Hd4, and Hd5 correspond to the head sliders 12a, 12c, 12d, 12e, and 12f, respectively.

  W consists of seek (read) -write-seek (read) -DC erase-seek (read), and corresponds to five rotations of the disk. The DC erase corresponds to a background process before writing a pattern. R repeats reading for 5 revolutions of the disk. One point on the X axis is a value for every 10 times of the W process or the R process. Since each process requires 5 revolutions, one point on the X axis corresponds to 50 revolutions of the disk. The Y axis is a PES value, and one servo write track corresponds to one PES. For example, for Hd0, the W process was performed 200 times (= 20 × 10) between 1 and 20 on the X axis, and the R process was performed 100 times between 21 and 30.

  As can be seen from FIG. 10, the head positions of Hd0 and Hd5 vary greatly in the R process. Further, fluctuations are also seen in the head positions of Hd3 and Hd4. The head position of Hd2 is kept almost constant. As shown in FIG. 2, since Hd2 (head slider 12c) is fixed to the same arm as Hd1 (head slider 12b), there is almost no fluctuation. The position of the other head slider 12 becomes larger as the distance from Hd1 (head slider 12b) increases.

  On the other hand, it can be seen from the measurement results in FIG. 10 that the head position can be returned to the position before the R process by executing the W process several times after the R process. Therefore, the SSW according to the present embodiment executes a sequence in which the average power consumption of the preamplifier IC 13 is higher than that in the calibration sequence between the calibration sequence and the pattern writing sequence. By executing this sequence, the amount of heat generated by the preamplifier IC 13 is increased, and the inclination of each head slider 12 is corrected. In this corrected state, the pattern writing sequence can be started.

  One of the preferable sequences for increasing the power consumption (heat generation amount) of the preamplifier IC 13 includes a dummy write process. In this dummy write sequence, the write element 122 is moved to the outer peripheral area where pattern writing is not performed, and writing is performed on the recording surface at the movement destination. For example, as shown in FIG. 11, after the write element 121 writes the servo write track of the radial pattern 117d and the calibration sequence is completed, the write element 121 moves to the write element position 121c.

  In the example of FIG. 11, the write element position 121c is located on the outer periphery side of the three servo write tracks from the servo write track written last before the calibration sequence. The read element 122 is positioned at the read element position 122g based on the read amplitudes of the radial patterns 117d, 117f, and 117g.

  At the destination, the write element 121 writes a preset pattern on the recording surface. Preferably, the write element 121 writes a DC or AC erase pattern on the recording surface. In particular, the DC erase pattern effectively increases the power consumption of the preamplifier IC 13 and does not adversely affect the reading of the timing pattern and the like. Typically, the write element 121 performs a dummy write for a plurality of rotations of the disk. The number of disk rotations for performing dummy writing depends on the HDD design.

  In the dummy write sequence, the SSW controller 22 controls the actuator 16 using the read signal of the propagation head, similarly to the normal pattern writing sequence and calibration sequence. In order to increase the power consumption and the heat generation amount of the preamplifier IC 13, it is preferable to write a pattern on each corresponding recording surface by all the head element units 12 held by the actuator 16.

  However, when a dummy pattern is written, the propagation head may not be able to read the radial pattern 117 accurately due to the influence of the pattern. In other words, since the base on which the radial pattern is written differs between the area where the dummy writing is performed and the area where the writing is not performed, there is a possibility that the pitch of the servo writing track where the dummy writing has been performed may fluctuate.

  Therefore, in one preferred method, dummy writing is not performed by the propagation head, but dummy writing is performed by the other head element unit 120. In order to raise the temperature of the preamplifier IC 13 as soon as possible, it is preferable that the SSW controller 22 selects all the head element units 120 other than the propagation head and performs dummy writing. Since the propagation head reads the pattern on the recording surface, adverse effects on head positioning can be prevented unless the propagation head writes a dummy pattern. Note that the SSW controller 22 selects the head element unit 120 for performing dummy writing by setting data for specifying the head element unit 120 in the register of the preamplifier IC 13.

  In another preferred method, the write element 121 performs dummy write while avoiding the area where the radial pattern 117 is written at the destination. As a result, the propagation head also performs dummy writing, and the power consumption and heat generation of the preamplifier IC 13 can be increased. This method is effective when the preamplifier IC 13 does not have a function of selecting the head element unit 120 that performs writing.

  In FIG. 12, each write element 121 (not shown in FIG. 11) has a servo write track to which the radial pattern 117i is written after the servo write track writing and calibration sequence of the radial pattern 117h is completed. Go to the track. In the servo write track, the write element 121 removes the area and writes the pattern in other areas without writing the pattern in the area where each radial pattern 117i is written.

  Alternatively, as shown in FIG. 13, the head element 122 may write the pattern on the recording surface of the movement destination by removing the entire area 171 of the slot where the radial pattern 117 is written in each servo write track of each sector. . All radial pattern slot areas in the servo write track are removed from the dummy write area. This example is inferior in terms of heat generation of the preamplifier IC because the area for writing the pattern is smaller than the example of FIG. However, in each dummy write process, it is only necessary to always write a pattern while avoiding the same area in each servo write track, so that the dummy write sequence can be controlled more easily.

  In the dummy write sequence, as one preferable method, a pattern is written by the write element 121 for a predetermined time. Typically, the writing time is defined by the rotational speed of the magnetic disk 11. This makes it easy to control the dummy write sequence. However, the inclination of each head slider 12 differs depending on the HDA and the head slider. In order to reliably correct the inclination of each head slider 12 regardless of variations, it is preferable to check the state of each head slider 12.

  One preferred method is to measure the deviation (inclination) of each head slider 12 from the target after executing a dummy write for a predetermined time by the write element 121. If this measured value is within the reference range, the next pattern writing sequence is started. If it is outside the reference range, the dummy write sequence is continued.

  Specifically, in the dummy write sequence, the SSW controller 22 first executes a dummy write for a predetermined number of disk revolutions. Thereafter, the actuator 16 is controlled using the read signal of the propagation head to position each head slider 12 at the target position. The target position can be, for example, a servo write track (read element position 122b in FIG. 7) where a pattern such as a product servo pattern is to be written next.

  With the actuator 16 positioned, each read element 122 reads the radial pattern. The SSW controller 22 calculates a PES value from the read amplitude value of the radial pattern 117. The SSW controller 22 compares the PES value with the target PES value, and determines whether the measured current PES value is within a reference range determined in advance from the target PES value. When the PES values of all the read elements 122 are within the reference range from each target PES value, the dummy write sequence ends and the next pattern write sequence starts.

  The target PES value corresponding to each head element unit 120 is acquired before performing the calibration sequence. That is, before the calibration sequence, each head element unit 120 moves to a position where a pattern is first written in the next servo pattern writing sequence. In the state of being positioned at that position, each head element unit 120 reads the radial pattern 117, and the PES value serving as a reference is specified.

  If the PES value of any read element 122 is outside the reference range from the target PES value, the dummy write sequence continues. The write element 122 moves to a predetermined position on the outer peripheral side and starts DC erase. The write element 122 performs DC erase for a predetermined reference time. Thereafter, the deviation of each head slider 12 from the target is measured again. By repeating the above processing, the inclination of each head slider 12 is reliably corrected.

  Here, in reading of the radial pattern 117 by each head element unit 120, the actuator 16 is positioned by using a signal read by the propagation head. The head element unit 12 for measuring the deviation from the target and the propagation head read the radial pattern 117 alternately for each sector (one slot). That is, the propagation head reads the radial pattern 117 when one sector occurs. In the servo pattern writing sequence, the actuator 16 is controlled by a read signal from the propagation head.

  Therefore, in the measurement of the inclination of each head element unit 12, accurate determination can be performed by performing positioning using the propagation head. Note that the head may be switched not for every sector but for every plurality of sectors. Alternatively, the propagation head may continuously read a plurality of sectors, and the measurement head element unit may subsequently read one sector.

  When the head slider 12 has an element other than the read 122 element and the write element 121, the preamplifier IC 13 outputs to this element, so that the power consumption and the heat generation amount can be increased. One of the preferable examples is an output to a heater provided in the head slider 12. The heater changes the amount of protrusion of the write element 121 and the read element 122 toward the recording surface, and controls the spacing (clearance) between the write element 121 and the read element 122 and the recording surface. Thereby, the optimum clearance can be realized without depending on the environmental temperature or the like.

  Since the heater consumes a large amount of power, the preamplifier IC 13 can raise the temperature of the preamplifier IC 13 by supplying a signal (power) to the heater of each head slider 12. In addition, when the actuator 16 has an element for position control and the preamplifier IC 13 outputs to the element, this output may be used for the heat generation of the preamplifier IC 13.

  As described above, it is preferable to correct the inclination of the head slider 12 by controlling the heat generation by the preamplifier IC 13, but the inclination of the head slider 12 is corrected or suppressed by a different method. be able to. That is, the tilt of the head slider 12 can be corrected by warming the inside of the actuator 16 or the HDA 1 by another heating method.

  For example, a heater is installed outside the HDA 1 that is executing SSW. After the calibration sequence, the top cover or base of the HDA 1 is heated by this heater to correct the tilt of the head slider 12. Alternatively, during the SSW, heating by an external heater and suppressing displacement of the actuator 16 due to a temperature change of the preamplifier IC 13 can suppress variations in the servo write track pitch. This can also be realized by installing the HDA 1 in a temperature-controlled chamber and executing SSW in the chamber.

  The head position correction sequence may be executed only after a part of the calibration sequence executed in the SSW. Thereby, the processing time of SSW can be shortened. Specifically, when the SSW has a servo pattern writing sequence including an erasing process and a servo pattern writing sequence not including the erasing process, the head position of this embodiment is set before the servo pattern writing sequence including the erasing process. It is preferable to execute a correction sequence.

  As an SSW technique, a method of writing a servo pattern while erasing the recording surface is known. Specifically, after writing the servo pattern, the write element 121 is moved to the outer peripheral side, and erase is executed at the movement destination. Thereafter, the write element 122 is returned to the inner peripheral side, positioned at the next target position, and a servo pattern is written. In this way, the servo pattern is written to each servo write track by alternately repeating the process of erasing several servo write tracks and writing a new servo pattern.

  For example, a method is known in which the outer peripheral side of the magnetic disk 11 is erased by an external magnetic field and then SSW is performed. In such a case, the SSW executes an erasing process on the inner peripheral side of the magnetic disk 11, and writes a servo pattern without performing erasing from a specific servo write track to the outer peripheral side.

  The heat generation amount of the preamplifier IC 13 in the servo pattern writing sequence including the erase process is larger than the heat generation amount in the sequence not including the erase process. For this reason, the influence of the temperature drop by a calibration sequence is large. Therefore, it is effective to execute the head position correction sequence before the servo pattern write sequence including the erase process.

  As mentioned above, although this invention was demonstrated taking preferable embodiment as an example, this invention is not limited to said embodiment. A person skilled in the art can easily change, add, and convert each element of the above-described embodiment within the scope of the present invention. For example, the present invention is not limited to an HDD, and can be applied to an apparatus that uses another type of disk. The servo / write control device 2 of this embodiment is a device different from the HDD, but it is also possible to incorporate a servo / write control function in the control circuit of the HDD. Note that the product servo pattern and the other patterns may not be the same number in the servo write track. The head position correction sequence of this embodiment is effective to be executed after the calibration sequence, but can be executed after another sequence in which the preamplifier IC heat generation amount changes greatly.

In this embodiment, it is a block diagram which shows typically the logic structure of the servo write control apparatus which controls the servo write of HDA and HDA. In this embodiment, it is a figure which shows typically the internal mechanism of HDA. In the present embodiment, the data format of the product servo pattern of one servo sector is shown. In the present embodiment, a pattern written on the recording surface by the SSTW and a writing method thereof are schematically shown. In the present embodiment, an example in which a read element is positioned at a target position and a pattern is written by a write element is schematically shown. In the present embodiment, an example of the reference APC for the servo write track is schematically shown. In this embodiment, it is a figure which shows typically the track pitch change in the pattern writing immediately after performing a calibration sequence. In this embodiment, it is a block diagram which shows typically the servo control system in SSTW. In the present embodiment, a method for moving the read element in the APC calibration sequence is schematically shown. In the present embodiment, the measurement result of the change in the PES value of each head slider as the read process continues is shown. In the present embodiment, a method of moving the head element portion in the dummy write sequence is schematically shown. In the present embodiment, a region in which the dummy write sequence is erased is schematically shown. In the present embodiment, a region where a dummy write sequence of another aspect is erased is schematically shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hard disk drive, 2 Servo write control apparatus, 10 Housing | casing 11 Magnetic disk, 12 Head slider, 13 Preamplifier IC
14 Spindle motor, 15 Voice coil motor, 16 Actuator 21 Pattern generator, 22 SSW controller 23 Read / write interface, 24 VCM driver 25 DA converter, 26 AD converter, 27 Amplitude demodulator 111 Servo area, 112 Data Area, 115 product servo pattern 116 timing pattern, 117 radial pattern,
118 Target position of read element, 119 Target position of write element 121 Write element, 122 Read element, 165 Rotating shaft, 162 Arm

Claims (13)

A plurality of heads that rotate in the housing using a plurality of heads in the housing, an actuator that supports and moves the heads in the housing, and a circuit element that is mounted in the housing and outputs a signal to the plurality of heads. A method of writing a pattern on each recording surface,
In the first sequence, a pattern on the corresponding recording surface is read by one propagation head in the plurality of heads, the plurality of heads are positioned by the actuator, and the plurality of heads are positioned on the plurality of recording surfaces in a positioned state. To write a new pattern, repeatedly write the pattern at each position in the radial direction on each recording surface by repeating the positioning and writing of the new pattern,
After the first sequence, execute a second sequence in which the heat generation state of the circuit element is lower than the first sequence,
Before newly writing a pattern adjacent to the pattern written in the first sequence, the circuit element is operated in a heat generation state higher than that in the second sequence, and then the adjacent pattern is written. In the second sequence, reading by at least one of the plurality of heads is continuously repeated.
The method of claim 1. Writing to the corresponding recording surface by at least one of the plurality of heads, thereby making the heat generation of the circuit element higher than in the second sequence;
The method of claim 1. Writing on the corresponding recording surface by a head other than the propagation head,
The method of claim 3. Write on the corresponding recording surface by the propagation head,
The area to be written is an area other than an area in which a pattern used for positioning of the propagation head is written.
The method of claim 3. After the heat generation of the circuit element is made higher than that in the second sequence, the pattern is read by the head different from the propagation head in a state where the pattern is read and positioned by the propagation head, Check the deviation from the target position,
The method of claim 1. The propagation head and the different head alternately read the pattern from the corresponding recording surface,
The method of claim 6. The second sequence is a calibration sequence for controlling the actuator.
The method of claim 1. A plurality of heads that rotate in the housing using a plurality of heads in the housing, an actuator that supports and moves the heads in the housing, and a circuit element that is mounted in the housing and outputs a signal to the plurality of heads. A method of writing a pattern on each recording surface,
A pattern is written on each recording surface by the plurality of heads,
Read the pattern on the corresponding recording surface with one of the plurality of heads, and move the plurality of heads with the actuator,
A method in which a new pattern is written by the plurality of heads in a state in which the inside of the housing is controlled by heating and is positioned using a read signal of the propagation head. Adjusting the temperature in the housing by increasing the heat generation amount of the circuit element mounted in the housing and outputting a signal to the plurality of heads;
The method of claim 9. The amount of heat generated by the circuit element is increased by writing an erase pattern on the corresponding recording surface by at least one of the plurality of heads.
The method of claim 10. A plurality of heads that rotate in the housing using a plurality of heads in the housing, an actuator that supports and moves the heads in the housing, and a circuit element that is mounted in the housing and outputs a signal to the plurality of heads. A method of writing a pattern on each recording surface,
In the first sequence, a pattern on the corresponding recording surface is read by one of the plurality of heads, the plurality of heads are positioned by the actuator, and a new state is determined by the plurality of heads on the plurality of recording surfaces in a determined state Write a pattern, repeat the positioning and writing of a new pattern, sequentially write the pattern to each position in the radial direction on each recording surface,
After the first sequence, execute a calibration sequence for controlling the actuator;
Before newly writing a pattern adjacent to the pattern written in the first sequence, writing to the corresponding recording surface by at least one of the plurality of heads, and then writing the adjacent pattern. The calibration sequence executes servo gain calibration of the actuator control.
The method of claim 12.

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