JP2007220204A - Testing method of disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a testing method of a disk drive which specifies a recording disk with a reduced squeeze margin. <P>SOLUTION: In a squeeze margin test, a HDD1 writes data of a data track Dtr_k at a target position Tt1. A write inhibiting value on the side of a data track Dtr_k+1 is Int2. After writing the data of the data track Dtr_k, the HDD1 writes the data of the data track Dtr_k+1 at a target position Tt2. The HDD1 writes the data while making the data track Dtr_k and the data track Dtr_k+1 close to each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a test method for a disk drive device, and more particularly to a write margin test between adjacent data tracks.

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

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

  In recent years, as the storage capacity of magnetic disks has increased and the recording density thereof has increased, the interval between data tracks and servo tracks (Track Per Inch: TPI) and the interval between data sectors (Bit Per Inch: BPI) have increased. It is getting narrower. Since the increase in BPI has a limitation from the point of SNR, the recording density is mainly improved by increasing the TPI. For this reason, the track interval of the data track is reduced, that is, the TPI is increased, and accordingly, a margin for fluctuation in the radial direction of the head element portion in data writing (hereinafter referred to as squeeze margin) is reduced.

  In actual data writing, the head element portion is not accurately positioned at the target position, but follows the target position while shaking in the radial direction. For this reason, when the squeeze margin is too small, there is a high possibility that the head element unit overwrites the adjacent data track of the target track (squeeze write).

  On the other hand, due to manufacturing tolerances, the squeeze margin varies for each HDD manufactured. Therefore, in the HDD manufacturing process, a test for finding an HDD having a squeeze margin that is too small is performed. If the test result of a specific HDD shows a squeeze margin that is too small, the HDD is removed from the shipment product group as a defective product.

  In a typical HDD manufacturing process, a squeeze margin test is performed on a part of data tracks selected from the recording surface of the magnetic disk instead of all data tracks in order to increase the manufacturing throughput. For example, the HDD arbitrarily selects three data tracks on the outer peripheral side, the center, and the inner peripheral side on the magnetic disk recording surface, and writes data therein. Further, on both sides of each selected data data track, the data of the adjacent data track is written close to each selected data track. The distance that the adjacent track is brought close is within an allowable range in the actual data writing of the adjacent track.

Although different from the squeeze margin test, a method for measuring the off-track margin of a magnetic disk is disclosed in, for example, Patent Document 1.
JP-A-6-84149

  As described above, in order to increase the throughput of the HDD manufacturing process, it is required to shorten the test time. On the other hand, it is important to prevent squeeze write under use by the user because it will cause erasure of user data. Accordingly, it is required to quickly and surely find a recording disk or HDD having a squeeze margin that is too small in the test process.

  However, in the squeeze margin test so far, the selection of the data track to be tested or the squeeze test method for the selected data track has not been sufficiently examined. For this reason, as the TPI increases, there is an increased possibility that a magnetic disk / HDD with a small squeeze margin will be overlooked in the manufacturing process and shipped to the user.

  According to one aspect of the present invention, there is provided a test method for a disk drive apparatus, wherein first data is written in a first data track on a recording disk, and second data is written in an adjacent second data track after the first data is written. The first data is read after the second data write, and the erase state of the first data by the second data is detected from the read first data, and the first data in the normal data write is detected. The target position of the track is Tn1, the target position of the second data track is Tn2, the target position for writing the first data is Tt1, the target position for writing the second data is Tt2, and the second data track Inhibition on the first data track side during normal data writing to The door value In1, the following relationship when the filled, | Tn1-Tn2 | - | Tt1-Tt2 | ≧ Inn1. By setting the distance between the target positions of the data track in this way, it is possible to perform a test under severe conditions where squeeze writing is more likely to occur, and the reliability of the test can be improved. Here, Tn1 = Tt1 or Tn2 = Tt2.

  Alternatively, it is preferable that the relationship | Tn1−Tn2 |> | Tn1−Tt2 |, | Tn1−Tn2 |> | Tn2−Tt1 | is satisfied. By bringing both two data tracks close to each other, it is possible to test under severe conditions in line with actual operation. Further, when the inhibit value on the second data side in the first data write is Int2, and the inhibit value on the first data side in the second data write is Int1, the following relationship is further satisfied. It is preferable that Inn1 + Inn2 = | Tn1−Tt1 | + Int2 ++ Tn2−Tt2 | + Int1. This allows testing under more severe conditions. Further, in the case where the inhibit value on the second data side in the first data write is Int2, and the inhibit value on the first data side in the second data write is Int1, the following relationship is further satisfied. Preferably, Inn1 = | Tn2−Tt2 | + Int1, Inn2 = | Tn1−Tt1 | + Int2. As a result, the test can be performed under more severe conditions in accordance with the actual operation.

  Further, the position signal value of the target position of the first or second data track in the normal operation is from the switching position signal value for switching the burst to be used to the adjacent switching position signal values on the inner and outer peripheral sides. It is preferable to be within a range of 1/4. Alternatively, it is preferable that the erase bandwidth on the first data track side of the second data track is equal to or larger than the erase bandwidth on the opposite side. With these, it is possible to test under more severe conditions.

  According to another aspect of the present invention, there is provided a test method for a disk drive device, wherein first data is written in a first data track on a recording disk, and second data is written in an adjacent second data track after the first data is written. The first data is read after the second data write, and the erase state of the first data by the second data is detected from the read first data, and the first data in the normal data write is detected. When the target position of the track is Tn1, the target position of the second data track is Tn2, the target position for writing the first data is Tt1, and the target position for writing the second data is Tt2. | Tn1-Tn2 |> | Tn1-Tt2 |, | Tn1-Tn2 |> | Tn2-Tt1 |. By writing the target positions of both data tracks close to each other, it is possible to perform tests under more severe conditions in accordance with actual operation.

  Further, the position signal value of the target position of the first or second data track in the normal operation is from the switching position signal value for switching the burst to be used to the adjacent switching position signal values on the inner and outer peripheral sides. It is preferable that the erasure bandwidth of the second data track on the first data track side is equal to or larger than the erasure bandwidth on the opposite side. This makes it possible to perform tests under more severe conditions.

  According to another aspect of the present invention, a head is positioned based on a position signal value generated using a plurality of bursts in servo data, and a burst to be used is switched according to a position signal value of a target in normal operation. A test method for a drive device, comprising: writing first data of a first data track; writing second data of a second data track adjacent to the first data track after writing the first data; The interval between the target position of the first data track and the target position of the second data track is smaller than the target position interval in normal data writing, and the first data is read after the second data writing, From the read first data, the first data is erased by the second data. The position signal value of the target position of the first or second data track in the normal operation is detected from the switching position signal value for switching the burst to be used, and the adjacent switching position signals on the inner and outer sides thereof. It is in the range within 1/4 to the value. When the position signal value of the target position of the first or second data track is in the above-described range, it is possible to perform a test under severe conditions in which squeeze writing is more likely to occur, and to improve the reliability of the test. .

  The position signal value at the target position of the first or second data track in the normal operation is 1/2 from the switching position signal value at which the burst to be used is switched to the adjacent switching position signal value at the inner and outer peripheral sides. It is preferable to be within the range of 8. Alternatively, the position signal value of the target position of the first or second data track in normal operation is preferably in the vicinity of the switching position signal value for switching the burst to be used. By these, it is possible to test under more severe conditions.

  According to another aspect of the present invention, there is provided a test method for a disk drive apparatus, wherein first data is written in a first data track selected on a recording disk, and the second data track adjacent to the first data track is written after the first data is written. , The second data is written closer to the first track than the normal operation write, and the erase bandwidth on the first data track side of the second data track is equal to or larger than the erase bandwidth on the opposite side. The first data is read after writing the second data without writing the data to the adjacent track opposite to the second data track with respect to the first data track, and the first data is read from the read first data. The erasure state of the first data by two data is detected. When the erase bandwidth satisfies the above relationship, the test can be performed under more severe conditions, and the test time can be shortened by erasing data only with one data track.

  The second data track is on the inner circumference side of the first data track, and further, third data is written in a third data track selected on the recording disk, and after the third data is written, In the fourth data track adjacent on the outer peripheral side, the fourth data is written closer to the third track than in the normal operation writing, and the inner peripheral erase bandwidth of the fourth data track is the erase on the outer peripheral side. The bandwidth is equal to or greater than the bandwidth, and the third data is read after the fourth data write without writing the data to the adjacent data track on the inner circumference side of the third data track, and the third data is read from the read third data. It is preferable to detect the erase state of the third data by the fourth data. Adding tests at different track positions can improve test reliability. Further, the test can be shortened by performing the test under more severe conditions when the erase bandwidth satisfies the above relationship and erasing the data only with one data track.

  According to the present invention, a recording disk with a small squeeze margin can be specified.

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

  In the following, embodiments of the present invention will be described by taking a hard disk drive (HDD) as an example of a disk drive device as an example. The HDD of this embodiment executes a squeeze margin test on a selected data track in the manufacturing process. The HDD of this embodiment executes its test by itself using a control circuit and a mechanical mechanism mounted as a product. Therefore, before describing the squeeze margin test of this embodiment, an outline of the overall configuration of the HDD will be described first.

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

  The HDD 1 further includes a circuit board 20 fixed to the outside of the enclosure 10. On the circuit board 20, there are 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.

  User data from the external host 51 is received by the HDC / MPU 23 and written to the magnetic disk 11 by the head element unit 12 via the R / W channel 21 and the AE 13. The user data stored in the magnetic disk 11 is read by the head element unit 12, and the user data is output from the HDC / MPU 23 to the external host 51 via the AE 13 and the R / W channel 21. The

  The magnetic disk 11 is fixed to the SPM 14. The SPM 14 rotates the magnetic disk 11 at a predetermined angular velocity. The motor driver unit 22 drives the SPM 14 according to control data from the HDC / MPU 23. Each head element unit 12 is fixed to a slider (not shown). Hereinafter, this assembly is referred to as a head slider. The head slider is fixed to the tip of the actuator 16. The actuator 16 is connected to the VCM 15, and moves in the radial direction on the magnetic disk 11 rotating the head element unit 12 (head slider) by swinging about the swing axis. The motor driver unit 22 drives the VCM 15 in accordance with control data (hereinafter referred to as 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. The write current value of the write element changes according to the control value set by the HDC / MPU 23. One or more magnetic disks 11 may be provided, and the recording surface can be formed on one side or both sides of the magnetic disk 11.

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

  In the HDC / MPU 23, the MPU operates according to the code loaded in the RAM 24. Along with the activation of the HDD 1, the RAM 24 is loaded with data necessary for control and data processing from the magnetic disk 11 or ROM (not shown) in addition to the code operating on the MPU. The HDC / MPU 23 performs necessary processing related to data processing such as read / write processing control, command execution order management, positioning control (servo control) of the head element unit 12 using a servo signal, interface control, defect management, etc. The entire control of the HDD 1 is executed. In particular, the HDC / MPU 23 of this embodiment performs execution control of the squeeze margin test. This will be described in detail later.

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

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

  The HDD 1 of this embodiment executes a defect test of the magnetic disk 11 itself. In this specification, this is called SRST (Self Run Self Test). The HDD 1 executes the SRST using its mechanical mechanism and a control circuit mounted as a product. As one of the test steps in the SRST, the HDD 1 executes a squeeze margin test.

  The manufacturing process of the HDD 1 includes a head stack assembly, which is an assembly of a head slider and an actuator 16, and necessary components such as a magnetic disk 11 mounted in the enclosure 10 to manufacture a head disk assembly (HDA). To do. Furthermore, the control circuit board 20 on which the above-described necessary circuits are mounted is mounted outside the HDA. The SRST is executed by the HDD 1 using its own circuit and mechanical mechanism when the HDD 1 as the product is assembled.

  In addition to the squeeze margin test, the SRST performs several types of defect detection tests on the recording surface of the magnetic disk 11, such as surface analysis test (SAT) and fill data. . In brief, the SAT specifies data on a magnetic disk by writing data to each data track of the magnetic disk 11 and reading the written data. The fill data executes a write process to the magnetic disk 11 and specifies a servo track that causes a write error and a data sector corresponding to the servo track.

  In the squeeze margin test of this embodiment, a test is performed on a part of data tracks selected from the recording surface of the magnetic disk 11. In a preferred mode, as shown in FIGS. 3A to 3C, a squeeze margin test is performed on two adjacent data tracks. FIG. 3A schematically shows the state of a normal data track. In this example, after writing the first data to the data track Dtr_k, the second data is written to the data track Dtr_k + 1. Then, the presence / absence of squeeze write is specified by reading the data of the data track Dtr_k and detecting the erased state. Accordingly, the first data of the data track Dtr_k is data to be squeezed and written, and the second data of the data track Dtr_k + 1 is data to be squeezed and written.

  In the squeeze margin test, the distance between the data track Dtr_k and the data track Dtr_k + 1 is made shorter than normal data writing. That is, the distance between the target positions of the data tracks is shorter than that of normal data writing. As shown in FIG. 3B, one of the modes for bringing the data track closer is to write the data track Dtr_k to the normal target address position and bring the target position of the data track Dtr_k + 1 closer to the Dtr_k side. In another mode, as shown in FIG. 3C, the target positions of both the data track Dtr_k and the data track Dtr_k + 1 are brought closer to each other.

  One of the features of this example is the distance that allows the data track Dtr_k and the data track Dtr_k + 1 to approach each other. In the conventional squeeze margin test, as shown in FIG. 3B, only the data track Dtr_k + 1 to be squeezed and written is brought close within the permitted range for normal data writing of the data track Dtr_k + 1. . On the other hand, in the squeeze margin test of this aspect, the data track Dtr_k and the data track Dtr_k + 1 are brought closer to each other than the allowable range of one data track.

  Here, an allowable range in normal data writing and a write inhibit value defining the allowable range will be described. When the head element unit is located outside the permitted range from the target servo address (target position), the HDC / MPU 23 does not write data. That is, the HDC / MPU 23 writes data to the magnetic disk 11 on the condition that the servo address read by the head element unit 12 is within the permitted range from the target servo address.

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

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

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

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

  Subsequently, the permission range in the normal writing process will be specifically described. FIG. 5 shows an example of the permitted range and the position of the head element unit 12 (read servo address). The permitted range is defined by two boundary PES values (write inhibit values) on the inner and outer peripheral sides of the target servo address. When the head element unit 12 (read element 122) moves away from the target servo address (TARGET) by a write inhibit value (WRITE INHIBIT) or more, the HDC / MPU 23 stops (aborts) the write process.

  In FIG. 5, the write-inhibit value in the permitted range is XPES (X is a positive integer, for example, 35 PES) on the inner and outer peripheral sides. Note that the write inhibit values on the inner peripheral side and the outer peripheral side can be designed differently. The HDC / MPU 23 selects one permission range according to the target servo address so as to compensate for the change in servo gain. Each circle 114a-114f in FIG. 5 represents a head position (servo address) calculated from each servo data read by the head element unit 12.

  When the PES value read by the head element unit 12 is more than the write inhibit value from the target servo address (target position) to the inner periphery or the outer periphery, the HDC / MPU 23 does not write data. That is, the HDC / MPU 23 does not start data writing before data writing, and stops data writing when data is being written. Thus, the data write condition is that the PES value is within the write inhibit value with reference to the target servo address.

  By prohibiting / permitting writing using the write inhibit value, data writing (squeeze writing) to the adjacent data track is prevented. Specifically, when the head element unit 12 moves to the head position 114f, the HDC / MPU 23 prohibits data writing. In other positions, data writing is not prohibited but permitted.

  When the necessary squeeze margin exists, the squeeze write can be prevented by the control using the write inhibit value. However, a squeeze write can occur if there is not enough squeeze margin due to manufacturing tolerances. In order to reliably find the magnetic disk 11 or the HDD 1 having a small squeeze margin, it is important to perform a test under conditions that are likely to cause squeeze write in normal data writing.

  In normal data writing, not only one of the adjacent data tracks approaches the other, but both data tracks can approach each other. In the conventional squeeze margin test, data is written to a data track to be squeezed and written, and then the adjacent data track is brought close to the permitted range for normal data writing. For example, when the write inhibit value of the normal data write process is 35 PES, the target servo address of the adjacent data track is brought close to the data track to be squeezed by 30 PES, and the data is written with the write inhibit value of 5 PES. Write.

  However, as described above, when adjacent data tracks approach each other, the data track interval becomes smaller and the possibility of causing a squeeze write is further increased. Therefore, in the present embodiment, a squeeze margin test is performed in consideration of data writing in a state where both adjacent data tracks are close to each other. In one mode, the HDD 1 writes the data track Dtr_k + 1 so as to be close to the data track Dtr_k, exceeding the write inhibit value for normal data writing, as shown in FIG.

  FIG. 6 specifically shows the target servo address and the write inhibit value in the example of FIG. The HDD 1 writes the data of the data track Dtr_k at the same target position as the normal data write. That is, the target position (target servo address) Tn1 in normal data writing and the target position Tt1 in this test are the same. On the other hand, the write inhibit value Int2 on the data track Dtr_k + 1 side in this test is smaller than the write inhibit value In2 in normal data writing. This point will be described later. The write inhibit value on the anti-data track Dtr_k + 1 side is not particularly limited, but may be the same as normal data writing.

  After writing the data of the data track Dtr_k, the HDD 1 writes the data of the data track Dtr_k + 1. The data writing position at this time is closer to the data track Dtr_k than the allowable range in normal data writing. The HDD 1 writes data in the data track Dtr_k + 1 within the range of the write inhibit value Int1 on the data track Dtr_k side at the target position Tt2. Obviously, Int1 <Inn1. Note that the write inhibit value on the opposite side of the data track Dtr_k is not particularly limited, but may be Int1.

At this time,
| Tn1−Tn2 | − | Tt1−Tt2 | ≧ Inn1 (1)
The relationship is established. | Tn1−Tn2 | is the target position interval between adjacent tracks in normal data writing, and | Tt1−Tt2 | is the target position interval between adjacent tracks in the squeeze margin test. This difference is greater than or equal to the normal write inhibit value on the data track Dtr_k side of the data track Dtr_k + 1.

| Tn1−Tn2 | − | Tt1−Tt2 | = Inn1 (2)
In this case, the target position Tt2 is located on the allowable range boundary in the normal data writing, but the writing position is closer to the data track Dtr_k than in the normal data writing in the range of the write inhibit value Int1. In order to test under more severe conditions,
｜ Tn1−Tn2 ｜ − | Tt1−Tt2 ｜ ＞ Inn1 （３）
Under the conditions, it is preferable that the HDD 1 writes data of the data track Dtr_k + 1. Typically, Inn2 and Inn1 are the same, but when Inn2 is larger, it is preferable to replace Inn1 in each of the above formulas with Inn2 in order to test under more severe conditions.

  As described above, the relationship Int2 <Inn2 is established. This is because the write position of the data track Dtr_k + 1 exceeds the permitted range for normal data write, so if Int2 = Inn2, the write position of the data track Dtr_k and the write position of the data track Dtr_k + 1 This is because there is a possibility that the data may not be able to occur in normal data writing.

For an accurate test, it is important that the writing position of the adjacent data track in the test is the same as that for normal data writing even in the closest case. Therefore,
| Inn2-Int2 | ≧ (| Tt2-Tn2 | + Int1) -Inn1 (4)
It is important to satisfy this relationship.

Preferably,
| Inn2-Int2 | = (| Tt2-Tn2 | + Int1) -Inn1 (5)
It becomes. Equation (5) indicates that the distance between the write position of the data track Dtr_k + 1 that can be closest to the data track Dtr_k in the test and the position that can be closest to the normal data write is the data track Dtr_k in the test and normal data write. It is equal to the difference of the write inhibit value. For the same reason, the following equation is satisfied.
｜ Tt2−Tn2 | <Inn1 + Inn2 (6)

  As described above, by setting the target position of one data track closer to the adjacent data track side than the permitted range for normal operation, it is possible to perform a test in a more severe state in which squeeze write is likely to occur. Further, when the test is performed with two data tracks as in the above-described preferred example, the test time can be shortened as compared with the conventional test using three data tracks.

  In the squeeze margin test described above, data is written to all data tracks, but a part of the data squeeze margin test may be written and tested. In the above description, the second data track is brought closer, but the normal target and the test target of the second data track are the same (Tt2 = Tn2), and the target position of the first data track is the second data track. It may be close to the track.

  The example of FIG. 6 changes only the target position Tt2 of the data track Dtr_k + 1 to be squeezed and written, and the target position Tt1 of the data track Dtr_k is the same as the target position Tn2 in normal data writing. However, in actual data writing, one data track does not approach the write inhibit value, and both data tracks approach each other within the write inhibit value. Therefore, it is preferable to perform a test according to this normal operation also in the squeeze margin test.

  Therefore, in the squeeze margin test, as shown in FIG. 3C, it is preferable that the target position Tt2 of the data track Dtr_k + 1 and the target position Tt1 of the data track Dtr_k are close to each other. By making the target positions of adjacent data tracks closer to each other than normal data writing, a squeeze margin test can be performed under more severe conditions, and a defective magnetic disk 11 or HDD 1 can be found more reliably.

  With reference to FIG. 7, a preferable mode in the case where the target positions of adjacent data tracks are brought close to each other as in the example of FIG. The HDD 1 writes data of the data track Dtr_k at the target position Tt1. The write inhibit value on the data track Dtr_k + 1 side is Int2. The inhibit value on the opposite side is not particularly limited, but may be the same as Int2. Note that Int2 <Inn2. For example, Inn2 is 35, Int2 is 5, and | Tt1−Tn1 | is 30.

  After writing the data of the data track Dtr_k, the HDD 1 writes the data of the data track Dtr_k + 1 at the target position Tt2. The write inhibit value on the data track Dtr_k side is Int1. The inhibit value on the opposite side is not particularly limited, but may be the same as Int1. Note that Int1 <Inn1. For example, Inn1 is 35, Int1 is 5, and | Tt2-Tn2 | is 30.

  From the viewpoint of bringing the data track closer, it is preferable to set the interval between the target values and Int1 and 2 to small values. However, if Int1 and 2 are too small, the test data write retry is repeated and the time becomes longer. Therefore, it is preferable to design in consideration of shortening the test time.

Here, since the target position Tt1 of the data track Dtr_k in the squeeze margin test is closer to the data track Dtr_k + 1 than the target position Tn1 in normal data writing, the following relationship is established.
| Tn1-Tn2 | >> | Tt1-Tn2 | (7)
That is, the distance between the target position Tt1 and the target position Tn2 is smaller than the distance between the target position Tn1 and the target position Tn2.

Similarly, since the target position Tt2 of the data track Dtr_k + 1 in the squeeze margin test is closer to the data track Dtr_k than the target position Tn2 in normal data writing, the following relationship is established.
| Tn1-Tn2 | >> | Tt2-Tn1 | (8)
That is, the distance between the target position Tt1 and the target position Tn2 is smaller than the distance between the target position Tn1 and the target position Tn2.

Since the test is performed under a severe condition in which squeeze write is likely to occur in actual operation, it is preferable that the boundary of the permitted range in normal data writing and the boundary of the permitted range in the squeeze margin test are equal. In other words, in the data writing of the data track Dtr_k, preferably
Inn2 = | Tt1−Tn1 | + Int2 (9)
Is established. In the data writing of the data track Dtr_k + 1,
Inn1 = | Tt2−Tn2 | + Int1 (10)
Is preferably established.

FIG. 7 shows a preferable example in which these mathematical expressions (9) and (10) are established. In order to make the conditions the same as the normal operation of the HDD 1, it is preferable that the squeeze margin test and the normal data write have the same permitted range boundary as shown in FIG. 7. However, from the viewpoint of bringing adjacent data tracks closer to each other, as described with reference to FIG. 6, one data track may be closer to the other data track than in normal operation. Therefore,
Inn1 + Inn2 = | Tt2-Tn2 | + | Tt1-Tn1 | + Int1 + Int2 (11)
The squeeze margin test may be performed under the condition that the above relationship is established.

  As described above, by making both the target values of adjacent data tracks close to each other, it is possible to perform a test in a stricter state close to normal operation. Further, when the test is performed with two data tracks as in the above-described preferred example, the test time can be shortened as compared with the conventional test using three data tracks. In the squeeze margin test described above, data is written to all data tracks, but a part of the data squeeze margin test may be written and tested. In addition, the distance between adjacent data tracks in the test is preferably the same as that for normal data writing, but may be changed depending on the design.

  In the above description, a preferred test method for the data track selected on the magnetic disk 11 has been described. Next, a preferred method for selecting the test data track will be described. Hereinafter, the magnetic disk 11 having a different data track pitch and servo track pitch will be described. One preferable test method in the HDD 1 selects a data track whose PES value of the target servo address is closer to 64 PES or 192 PES as a test track. Before specifically describing the selected track, first, the data format on the magnetic disk 11 will be described.

  FIG. 8 schematically shows a part of the data area 112 and the servo area 111. FIG. 8 is a schematic diagram and does not accurately reflect the actual format. The magnetic disk 11 of this embodiment records data according to an adaptive format in which the data track pitch and the servo track pitch are different. The data track pitch is larger than the servo track pitch, preventing squeeze write and off-track write and improving reliability.

  Further, FIG. 8 schematically shows the positions of the write element 121 and the read element 121 at the time of data reading and data writing. In this example, when the head element unit 12 is positioned on the magnetic disk 11, the write element and the read element are at different positions in the radial direction. This difference (distance) in the radial direction between the write element and the read element is called a read / write offset.

  In FIG. 8, a write element 121a and a read element 122a indicate head positions at the time of data reading, and a write element 121b and read element 122b indicate head positions at the time of data writing. Specifically, the read element 122a is positioned at a position for reading the data track DTr_m. On the other hand, the read element 122b is positioned at a position where the write element 121b writes user data to the data track DTr_m-2.

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

  Returning to FIG. 4B, the position in the servo track is represented by PES values divided into 256 in the radial direction. The PES is determined by the burst pattern. Specifically, the HDD 1 of the present embodiment controls the positioning of the main PES (MPES) calculated using the burst A and the burst B and the secondary PES (SPES) calculated using the burst C and the burst D. Used in. MPES is calculated using | A−B | / (A + B). The SPES is calculated using | C−D | / (C + D). Here, each alphabet represents a read amplitude value of each burst. The HDC / MPU 23 changes the PES used according to the head position.

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

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

  FIG. 9 shows the relationship between the PES and the actual physical movement amount of the head element unit 12. As shown in FIG. 5, in the vicinity of 64 PES and 192 PES, the relationship between the PES and the physical movement amount is different from other regions, and there is a distortion of the relationship. Specifically, the change rate of the physical movement amount with respect to the PES change amount increases in the vicinity of 64 PES and 192 PES.

  In an ideal state, the PES and the physical movement amount have a linear relationship. However, in actual products, these do not satisfy a strict linear relationship. Therefore, it is necessary to correct the value calculated from the actually read burst signal. FIG. 9 shows the relationship between the corrected PES and the physical movement amount. Since MPES and SPES use different bursts, these values are not continuous in the actual HDD 1, and it is necessary to make these values continuous by correction. Distortion in the vicinity of 64 PES and 192 PES is caused by this correction. In particular, this discontinuity becomes more prominent as the track pitch decreases.

  As understood from FIG. 9, in the vicinity of 64 PES and 192 PES, the change amount of PES corresponding to the change of the physical movement amount is small. That is, in practice, the PES does not change so much even though the head element portion 12 is greatly moved in the radial direction of the magnetic disk 11. In this specification, the amount of change in PES with respect to the amount of physical movement is referred to as servo gain. That is, the servo gain is reduced in the vicinity of 64 PES and 192 PES.

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

  Therefore, there is a high possibility that squeeze light will occur in the vicinity of 64 PES and 192 PES. In order to detect an error disk or an error HDD more reliably, it is preferable to perform a squeeze margin test under conditions where there is a high possibility that squeeze write will occur. Therefore, the test data track preferably has a target servo address that includes a PES value closer to 64 PES or 192 PES. The data track selected in this range may be either a squeeze-written data track or a squeeze-written data track.

  Therefore, as shown in FIG. 10, the HDD 1 of this embodiment has a PES value of the target servo address of the test data track within the 32 PES range on the OD side and ID side with 64 PES as the center, or , 192 PES and the one within the 32 PES range on the OD side and ID side as the center are selected. For example, in FIG. 10, it is an area between 32 PES and 96 PES centering on 64 PES. Here, 32 PES is 1/4 of the distance (interval) between 64 PES and 192 PES which are adjacent positions for switching bursts. The PES value in this area is closer to 64 PES or 192 PES than the PES values in other areas.

  More preferably, the PES value of the target servo address of the test data track is within the range of 16 PES on the OD side and ID side around 64 PES, or on the OD side and ID side around 192 PES. Select those within each 16 PES range. Here, 16 PES is 1/8 of the distance (interval) between 64 PES and 192 PES which are adjacent positions for switching bursts. By selecting a data track closer to the burst switching position, testing under more severe conditions is possible.

  Most preferably, a data track is selected in which the PES value of the target servo address substantially matches 64 PES or 192 PES. However, depending on the design of the HDD, there may be no 64 PES or 192 PES data track at the desired position on the magnetic disk. Therefore, it is preferable to select a data track that includes the target servo address within the vicinity of 64 PES or 192 PES, specifically, within the range of ± 5 PES. This is approximately 1/25 of the distance (spacing) between 64 PES and 192 PES.

  As described above, a squeeze margin test is performed on a test track having a target servo address near the burst switching position on a magnetic disk having a different data track pitch and servo track pitch. Tests can be performed under conditions where squeeze lights are likely to occur in operation. In the test method described with reference to FIG. 6 or FIG. 7, it is preferable to select the data track described above, but these can be used individually as another test method.

  Next, a preferred embodiment of a method for selecting a data track to be squeezed and a data track to be squeezed will be described. As described with reference to FIGS. 6 and 7, when two adjacent data tracks are selected and a squeeze margin test is performed, one of the inner and outer data tracks is written first, After that, the other data track is written. When the erase band of the head in the data track to which data is to be written later is different between the inner peripheral side and the outer peripheral side, it is preferable that the wide erase band is on the data side on which data was written first.

  That is, in the example of FIG. 3, it is preferable that the squeeze band on the outer peripheral side of the data track Dtr_k + 1 is wider than the inner peripheral side. In other words, it is preferable to select two data tracks so that this relationship is satisfied. As a result, it is possible to perform a test under a condition where the possibility of squeeze / write is high. When a data track to be squeezed and written is selected under such conditions, it is not necessary to write test data to the data track on the opposite side (data track Dtr_k−1 in FIG. 3). Thereby, the test time can be shortened.

  The relationship between the data track and the erase band will be described with reference to FIGS. As shown in FIG. 11, the recording surface of the magnetic disk 11 is divided into OD, MD, and ID areas. FIGS. 12A, 12B, and 12C schematically show the relationship between the head skew and the erase band. 12A shows a state in which the head element unit 12 is positioned on a track in the ID area, FIG. 12B shows a state in which the head element unit 12 is positioned on a track 118 in the MD area, and FIG. Indicates a state in which the head element portion 12 is positioned on a track in the OD region.

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

  The head skew angle, which is the angle of the head element portion 12 with respect to the data track, is negative in FIG. 12A, 0 in FIG. 12B, and positive in FIG. 12C. As understood from FIGS. 12A to 12C, the widths of the erase bands 115a and 115b vary depending on the head skew angle. With reference to the width of erase bands 115a and 115b when the head skew angle is 0 in FIG. 12B, the erase band 115b on the outer peripheral side is wide in the ID side track shown in FIG. The inner erase band 115a is narrow. On the other hand, in the OD track shown in FIG. 12C, the erase band 115a on the inner peripheral side is wide and the erase band 115b on the outer peripheral side is narrow.

  A typical squeeze margin test selects a data track from the ID area, MD area, and OD area, and tests the data track. Accordingly, in the squeeze margin test, for example, when a data track in the ID area is selected, a data track on the inner circumference side of the data track into which data is written is selected as a data track into which data is written later. Is preferred. In the example of FIG. 12A, the HDD 1 writes data to the data track 116a after writing data to the data track 116b.

  On the other hand, when a data track in the OD area is selected, it is preferable to select a data track on the outer periphery side of the data track into which data is written as a data track into which data is written later. In the example of FIG. 12C, the HDD 1 writes data to the data track 116c after writing data to the data track 116b.

  When a data track in the MD area is selected, a data track to which data is written later changes depending on the position of the data track. That is, when a data track into which data is to be written later is located on the inner circumference side of the data track 118, the data track is preferably an adjacent track on the inner circumference side than the data track into which data is written first. On the other hand, when a data track into which data is to be written later is located on the outer peripheral side of the data track 118, the data track is preferably an adjacent track on the outer peripheral side of the data track into which data is written first.

  In this way, by determining the data track to which data will be written later according to the erase band of the data track, the test is performed under a condition where a squeeze write is likely to occur in actual operation, and the squeeze margin is reduced. The insufficient magnetic disk 11 or HDD 1 can be identified more reliably. In addition, the test time is shortened by testing two adjacent data tracks, writing test data to only one side of the squeeze-written data track, and not writing test data to both sides. Can do.

  The relationship between the data track and the head skew angle varies depending on the HDD design. For example, the head skew angle can be designed to always be negative, or the data track with head skew 0 can be designed to be near the innermost circumference or near the outermost circumference. Even in such a case, the data track may be selected according to the width of the erase band of the data track to which data will be written later.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, the present invention is suitable for an HDD, but can be applied to other disk drives. Or although the test in the manufacturing process of HDD was demonstrated above, you may perform the above-mentioned test in the initialization process at the time of HDD power supply after shipment, etc. turning on.

  In the above description, the method for selecting the test track according to the PES and the erase band and the method for testing the selected adjacent data track have been described. From the viewpoint of shortening the test time and improving the test reliability, it is preferable to use these conditions and methods together, but it is of course possible to use each method independently. That is, the conventional test can be performed on the data track selected according to the PES and / or the erase band, or the test described with reference to FIGS. Alternatively, the test described with reference to FIGS. 6 and 7 can be performed on arbitrarily selected data tracks.

In this embodiment, it is a block diagram which shows typically the whole structure of HDD. In this embodiment, it is a figure which shows typically the state of the recording data of the recording surface of a magnetic disc. In the squeeze margin test of this embodiment, a state in which adjacent data tracks are brought close to each other is schematically shown. In this embodiment, it is a figure which shows typically the data format of servo data. In this embodiment, it is a figure which shows an example of a permission range and the position (read servo address) of a head element part. FIG. 6 is a diagram schematically illustrating an example in which only one adjacent track is brought close to the other in the squeeze margin test of the present embodiment. It is a figure which shows typically the example which adjoins the adjacent track | truck of both sides mutually in the squeeze margin test of this embodiment. In this embodiment, it is a figure which shows typically the position of the write element at the time of data reading and data writing, and a read element. In this embodiment, it is a figure which shows typically the relationship between PES and the actual physical displacement of a head element part. In this embodiment, it is a figure which shows typically the range of the test track selected according to PES. In this embodiment, it is a figure which shows typically the relationship between the head skew with respect to a data track, and a data track position. In this embodiment, it is a figure which shows typically the relationship between a head skew and an erase band.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Enclosure, 11 Magnetic disk, 12 Head element part 13 Arm electronics, 14 Spindle motor 15 Voice coil motor, 16 Actuator, 20 Circuit board 21 R / W channel, 22 Motor driver unit, 23 HDC / MPU
24 RAM, 51 Host, 111 Servo area, 112 Data area 113a-c Zone, 115a, b Erase band 116a-c Data track, 118 Data track 121a, b Write element, 122a, b with zero head skew Lead element, 124a, b Magnetic pole

Claims (14)

Write first data in a first data track on the recording disk;
Writing second data in a second data track adjacent after writing the first data;
The first data is read after the second data write, and the erase state of the first data by the second data is detected from the read first data,
In the normal data write, the target position of the first data track is Tn1, the target position of the second data track is Tn2,
The target position for writing the first data is Tt1, the target position for writing the second data is Tt2,
In the normal data write to the second data track, the inhibit value on the first data track side is set to In1,
If the following relationship is satisfied,
｜ Tn1−Tn2 ｜ − | Tt1−Tt2 ｜ ≧ Inn1
Test method for disk drive devices.   The method of claim 1, wherein Tn1 = Tt1 or Tn2 = Tt2. In addition, the following relationship is satisfied:
｜ Tn1−Tn2 ｜ ＞ ｜ Tn1－Tt2 ｜
｜ Tn1－Tn2 ｜ ＞ ｜ Tn2－Tt1 ｜
The method of claim 1. Int2 represents the inhibit value on the second data side in writing the first data,
In the case where the inhibit value on the first data side in the writing of the second data is Int1, the following relationship is satisfied.
Inn1 + Inn2 = | Tn1-Tt1 | + Int2 ++ | Tn2-Tt2 | + Int1
The method of claim 3. Int2 represents the inhibit value on the second data side in writing the first data,
In the case where the inhibit value on the first data side in the writing of the second data is Int1, the following relationship is satisfied.
Inn1 ＝ ｜ Tn2−Tt2 ｜ ＋ Int1
Inn2 = | Tn1−Tt1 | + Int2
The method of claim 4.   Further, the position signal value of the target position of the first or second data track in the normal operation is from the switching position signal value for switching the burst to be used to the adjacent switching position signal values on the inner and outer peripheral sides. The method of claim 1, which is in the range of no more than ¼.   The method according to claim 1, wherein the erase bandwidth on the first data track side of the second data track is greater than or equal to the erase bandwidth on the opposite side. Write first data in a first data track on the recording disk;
Writing second data in a second data track adjacent after writing the first data;
The first data is read after the second data write, and the erase state of the first data by the second data is detected from the read first data,
In the normal data write, the target position of the first data track is Tn1, the target position of the second data track is Tn2,
The target position for writing the first data is Tt1, the target position for writing the second data is Tt2,
If the following relationship is satisfied,
｜ Tn1−Tn2 ｜ ＞ ｜ Tn1－Tt2 ｜
｜ Tn1－Tn2 ｜ ＞ ｜ Tn2－Tt1 ｜
Test method for disk drive devices. Further, the position signal value of the target position of the first or second data track in the normal operation is from the switching position signal value for switching the burst to be used to the adjacent switching position signal values on the inner and outer peripheral sides. Within a quarter,
9. The method according to claim 8, wherein an erase bandwidth on the first data track side of the second data track is equal to or greater than an erase bandwidth on the opposite side. A test method for a disk drive device that positions a head based on position signal values generated using a plurality of bursts in servo data and switches the burst to be used according to the position signal values in normal operation,
Write the first data of the first data track;
After the writing of the first data, the second data of the second data track adjacent to the first data track is written, and between the target position of the first data track and the target position of the second data track The interval is smaller than the target position interval in normal data writing,
The first data is read after the second data write, and the erase state of the first data by the second data is detected from the read first data,
The position signal value at the target position of the first or second data track in the normal operation is 1/2 from the switching position signal value at which the burst to be used is switched to the adjacent switching position signal value at the inner and outer peripheral sides. A method in the range of 4 or less.   The position signal value at the target position of the first or second data track in the normal operation is 1/2 from the switching position signal value at which the burst to be used is switched to the adjacent switching position signal value at the inner and outer peripheral sides. 11. The method of claim 10, wherein the method is in the range of 8.   The method according to claim 10, wherein the position signal value of the target position of the first or second data track in normal operation is in the vicinity of a switching position signal value for switching a burst to be used. Write first data in a selected first data track on the recording disk;
After the first data writing, the second data is written closer to the first track than the normal operation writing in the adjacent second data track, and the erase data on the first data track side of the second data track is written. The bandwidth is equal to or greater than the opposite erase bandwidth,
The first data is read after writing the second data without writing the data to the adjacent track opposite to the second data track for the first data track, and the second data is read from the read first data. Detecting the erasure state of the first data by data,
Test method for disk drive devices. The second data track is on the inner circumference side of the first data track;
Furthermore, the third data is written in the third data track selected on the recording disk,
After writing the third data, the fourth data track is written closer to the third track than the normal operation write in the fourth data track adjacent on the outer periphery side, and the erase band on the inner periphery side of the fourth data track is written. The width is equal to or greater than the erase band width on the outer peripheral side,
The third data is read after writing the fourth data without writing data to the adjacent data track on the inner circumference side of the third data track, and the third data by the fourth data is read from the read third data. Detecting data erasure status,
The method of claim 13.

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