JP2009076184A - Storage device, servo information writing method, seek control method, and control circuit - Google Patents

Abstract

An object of the present invention is to correctly detect a boundary cylinder even in a storage medium having a single head and to prevent deterioration of servo quality.
The storage device performs normal operation from the outer side based on predetermined cylinder information that is a boundary detected by using servo information that is written with double servo from the inner side and not overwritten with servo information that is written from the outer side. When the head is on-tracked to the track on the inner side of the specified cylinder, the difference is subtracted from the specified cylinder information that is the boundary detected using the servo information written by the servo. Servo information obtained by adding the extracted differences is read using the head, and the position of the head is controlled using the read servo information.
[Selection] Figure 1

Description

  The present invention demodulates the written servo information to obtain cylinder information by demodulating the written servo information for a storage medium where the boundary between the servo information written from the inner side and the servo information written from the outer side exists. The present invention relates to a storage device that controls the position of a head for reading and writing, a servo information writing method, a seek control method, and a control circuit.

  Conventionally, the recording density of storage media such as magnetic disks, magneto-optical disks, and optical disks has been remarkably improved. As a result, it is possible to reduce the size of the storage device and increase the recording capacity, and the convenience of the storage device is increasing.

  In such a high-density storage medium, in order to accurately position the head on the target track, a servo pattern (servo mark) for demodulating the track number and the relative position of the head to the track center, etc. Servo information as information is written by an STW (servo track writer). This STW writes servo information from one direction from the outer side or inner side of the storage medium. A control device such as a storage device uses this servo information to automatically control a head that reads and writes data from the storage medium (see Patent Document 1).

  When writing servo information using this STW, the servo quality written to the storage medium due to erasing, which is called side fringe, has deteriorated, and servo mark errors and gray code (Graycode) errors are detected when the servo information is read by the head. Etc. is a problem. The side fringe is caused by the magnetic field leakage (writing spread) of the write head that writes servo information to the storage medium. As shown in FIG. 15, the side fringe is closely related to the head yaw angle (YAW angle) and the STW feed direction. Yes. Specifically, as shown in FIG. 16, if the Outer direction is written, the Outer side is greatly affected by side fringes, and the Inner side is greatly affected by side fringes, and the erase portion becomes large, and the servo quality is greatly deteriorated. In recent years, as TPI (Track Per Inch: Track Density) continues to increase, the deterioration of servo information error rate and head Position quality due to the deterioration of servo quality cannot be ignored. FIG. 15 is a diagram showing a relationship between the yaw angle and the STW feed direction, and FIG. 16 is a diagram for explaining an erase portion in the STW feed direction.

  As a technique to prevent such error rate deterioration and Position quality deterioration due to deterioration of servo quality, servo information is written while sending the STW head to the Inner side on the Outer side, and servoing while sending the STW head to the Outer side on the Inner side. A bidirectional STW for writing information is used. By using this two-way STW, a boundary exists between the servo information written from the outer side and the servo information written from the inner side. This boundary shifts in the time direction and the radial direction without coincidence due to a change in the environment in which the servo information is written again, and this shift causes the servo not to be detected or erroneously detected (FIG. 17). reference). In order to use the bi-directional STW, it is necessary to perform correction processing for accurately reading out or detecting the servo information written in the boundary portion (boundary cylinder: boundary cylinder). It is important to detect well. FIG. 17 is a diagram showing the deviation of the written servo information in the time direction and the radial direction.

Japanese Patent No. 2645182

  However, in the conventional technique described above, in a storage medium having one head, a cylinder serving as a boundary cannot be detected correctly. Therefore, a servo information error rate deterioration due to servo quality deterioration or head position quality deterioration. There was a problem that occurred. Specifically, the boundary cylinder is generally changed on both sides of the storage medium, and the boundary cylinder is calculated by performing a head-to-head deviation measurement by several zones, so only one head is mounted. In a storage medium such as a hard disk, a track (or cylinder) serving as a boundary cannot be obtained. As a result, servo information correction processing for accurately reading or detecting servo information written in the boundary portion (boundary cylinder: boundary cylinder) cannot be performed, and servo information due to deterioration of servo quality. The error rate deteriorates and the head position quality deteriorates.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and can correctly detect a track serving as a boundary even in a storage medium having a single head and prevent deterioration of servo quality. It is an object of the present invention to provide a storage device, a servo information writing method, a seek control method, and a control circuit.

  In order to solve the above-described problems and achieve the object, the present invention performs a first servo write process in which two identical servo information are written in parallel in a vicinity region including a predetermined cylinder, A second servo writing process for writing servo information so as to overwrite one servo information among the two servo information written by the first servo writing process and the second servo writing process is performed in the predetermined cylinder. A storage medium in which servo information is written in duplicate, a head for reading out the information written in the storage medium, and cylinder information of the predetermined cylinder in the storage medium is written by the second servo writing process. In the first boundary detection unit that reads and detects servo information by the head, and in the storage medium, A second boundary detector for reading out and detecting the servo information of the fixed cylinder, which is written by the first servo writing process and not overwritten in the second servo writing process, by the head; and the first boundary A difference extraction unit that extracts a difference between cylinder information detected by the detection unit and cylinder information detected by the second boundary detection unit; a predetermined cylinder written by the first servo writing process; Servo information obtained by adding or subtracting the difference extracted by the difference extraction unit to the on-track position when the head moves on track between the predetermined cylinder written by the two servo writing process Read out using the head and control the position of the head using the read servo information And characterized in that it comprises a location control unit.

  Further, in the present invention, when the difference extracted by the difference extraction means is a negative value, the storage medium in which the cylinder information in which the negative value is detected exists is externally described. It is characterized by having a rejection part to notify.

  Further, the present invention is the storage medium according to the above invention, wherein the storage medium in which the servo information that is not overwritten in the second servo writing process is written using a special mark pattern in the first servo writing process. The head position control unit does not use servo information written with the special mark pattern in the storage medium for position control of the head.

  Further, the present invention is the above invention, wherein the head position control unit skips the vicinity of a predetermined cylinder detected by the outer side boundary detection unit in the storage medium and does not use it as a user area. The position of the head is controlled.

  Further, according to the present invention, in the above-described invention, a first servo write process is performed in which two identical servo information is written in parallel in a vicinity region including a predetermined cylinder, and the two servo servo processes written by the first servo write process are performed. A second servo writing process is performed to write servo information so that one servo information of the servo information is overwritten, and the servo information overlaps and is stored in the predetermined cylinder by the first servo writing process and the second servo writing process. It is characterized by writing on a medium.

  In the present invention, the difference detection unit may calculate a difference between cylinder information detected by the first boundary detection unit and cylinder information detected by the second boundary detection unit at a plurality of locations of the storage medium. It is characterized by extracting.

  Further, according to the present invention, in the above invention, the servo information written in the first servo write process while the head follows predetermined cylinder information on the servo information written in the second servo write process. And reading the cylinder information on the servo information that has not been overwritten by the second servo writing process, so that the difference extraction unit detects the cylinder information detected by the first boundary detection unit and the second boundary A difference from the cylinder information detected by the detection unit is extracted.

  Further, according to the present invention, in the above-described invention, a first servo write process is performed in which two identical servo information is written in parallel in a vicinity region including a predetermined cylinder, and the two servo servo processes written by the first servo write process are performed. A second servo writing process for writing servo information so as to overwrite one of the servo information is performed, and the servo information is duplicated in the predetermined cylinder by the first servo writing process and the second servo writing process. A written storage medium, a head for reading information written to the storage medium, cylinder information of the predetermined cylinder in the storage medium, and servo information written by the second servo writing process by the head. A first boundary detection step of reading and detecting; and in the storage medium, the predetermined cylinder Cylinder information is detected by the first boundary detection step and the second boundary detection step in which the servo information written by the first servo writing processing and not overwritten in the second servo writing processing is read and detected by the head. And a difference extraction step for extracting a difference between the cylinder information detected by the second boundary detection step and the cylinder information detected by the second boundary detection step. When the head moves on track between the predetermined cylinder and the predetermined cylinder written by the second servo writing process, the difference extraction step extracts the on-track position. Read the servo information with the difference added or subtracted using the head, and read the servo information There are characterized by seeking the head to the target position.

  In the present invention, the storage device may further include an actuator that supports the head, and a voice coil motor that seeks the actuator by energizing a current. When the current position does not match, the current value is changed by a minute amount.

  In the present invention, the present invention further calculates a position error from the target position and the current position, detects that the vicinity of the target position is reached, switches to following control, and executes the following control. It is characterized by doing.

  Further, according to the present invention, in the above-described invention, a first servo write process is performed in which two identical servo information is written in parallel in a vicinity region including a predetermined cylinder, and the two servo servo processes written by the first servo write process are performed. A second servo writing process for writing servo information so as to overwrite one of the servo information is performed, and the servo information is duplicated in the predetermined cylinder by the first servo writing process and the second servo writing process. A control circuit for seeking a head for reading information written on the storage medium on the written storage medium, and writing cylinder information of the predetermined cylinder in the storage medium by the second servo writing process. Read the servo information by the head that reads the information written in the storage medium. A first boundary detection unit that outputs the cylinder information of the predetermined cylinder in the storage medium, and servo information that has been written by the first servo writing process and not overwritten in the second servo writing process by the head. A second boundary detection unit that reads and detects, a difference extraction unit that extracts a difference between cylinder information detected by the first boundary detection unit, and cylinder information detected by the second boundary detection unit; When the head moves on track between a predetermined cylinder written by one servo writing process and a predetermined cylinder written by the second servo writing process, the head is moved to the on-track position. Servo information obtained by adding or subtracting the difference extracted by the difference extraction unit is read using the head, and read. And characterized in that it comprises a head position controller for controlling the position of the head by using the servo information.

  According to the present invention, even in a storage medium with one head, it is possible to correctly detect a cylinder serving as a boundary and prevent deterioration in servo quality. In addition, as a result of using a storage medium with high servo quality, it is possible to contribute to an increase in TPI of the storage medium.

  Exemplary embodiments of a storage device, a servo information writing method, a seek control method, and a control circuit according to the present invention will be described below in detail with reference to the accompanying drawings. In the following, the main terms used in this embodiment, the outline and features of the storage device according to this embodiment, the configuration of the storage device and the flow of processing will be described in order, and finally various modifications to this embodiment will be described. explain.

[Explanation of terms]
First, main terms used in this embodiment will be described. The “storage device” includes a disk for recording data, a head for reading and writing data on the disk, and a voice coil motor (VCM) for rotating the arm to move the head to a predetermined position. It is a device mainly composed of a control circuit for controlling these. In the “storage device”, the disk is rotated at a constant rotational speed by an SPM (spindle motor), and data is read or written while the head is flying above the disk.

  Incidentally, data reading is realized by positioning the head at a predetermined position of the disk and reading the data recorded at the predetermined position. Data writing is realized by positioning the head at a predetermined position on the disk and writing the data at the predetermined position. Such head positioning is controlled by a micro-control unit (MCU) of the storage device.

  The “MCU” that controls the position of the head performs position control by reading “servo control data” stored in addition to “user data” that is data used for processing in the host computer on the disk. Since this “servo control data” records position information on the disk, when “servo information (servo control data)” read by the head is transmitted to “MCU”, “MCU” Calculates the current position of the head. Next, the “MCU” performs a filter calculation based on the current position of the head, and controls the VCM with a control value obtained by the filter calculation. As described above, the VCM is a driving unit that moves the head to a predetermined position. Therefore, when the VCM is controlled, the positioning of the head is controlled.

  As described above, since the “MCU” controls the position of the head by reading the “servo information” stored in the disk and performing the filter calculation, it is necessary to read the “servo information” accurately in the storage device. This is important for head positioning control. In addition, if the “servo information” is not accurately written on the disk, the “servo information” read by the “MCU” at the time of head position control also lacks accuracy. It is also important to write the “servo information” accurately.

[Outline and Features of Storage Device]
Next, the outline and features of the storage device according to the first embodiment will be described with reference to FIG. FIG. 1 is a diagram for explaining the outline and features of the storage device according to the first embodiment.

  This storage device obtains cylinder information by demodulating the written servo information to a storage medium where there is a boundary between the servo information written from the inner side and the servo information written from the outer side. It is possible to control the position of the head that reads and writes data, and in particular, even in a storage medium with a single head, it is possible to correctly detect the boundary cylinder and prevent degradation of servo quality. This is the main feature.

  Specifically, the main feature is that the storage device is subjected to a first servo writing process in which two identical servo information is written in parallel from the inner cylinder toward a predetermined cylinder on the outer side. The second servo writing process for writing the servo information so as to overwrite one servo information of the two servo information written by the first servo writing process from the outer cylinder toward the predetermined cylinder on the inner side is performed. A storage medium in which servo information is written in duplicate in a predetermined cylinder by the first servo writing process and the second servo writing process is received (see (1) in FIG. 1). In the present embodiment, the track of the innermost cylinder is described as gray code “10000 Track”, and the track of the outermost cylinder is described as gray code “1000 Track”. The predetermined cylinder shown here is a “boundary” of servo information written by the first servo writing process and the second servo writing process.

  Specifically, the storage device writes two identical servo information in parallel from the innermost cylinder Gray code (10000 Track) to a predetermined cylinder (boundary), and the two servos written from the innermost cylinder. A storage medium in which one piece of servo information is written is received from the gray code (1000 Track), which is the outermost cylinder, to the boundary so that one piece of servo information is overwritten.

  For example, the storage device double-writes the same servo information “SV0 / SV0 (double), SV1 / SV1 (double),...” From the gray code (10000 Track) to the boundary (5007 Track) in parallel. Servo information is written by the normal servo that writes one servo information so that the servo information is overwritten by “SV0, SV1, SV2,...” Written from the innermost cylinder. Accept the written disc.

  In other words, in the storage device, servo information is written by normal servo from the outermost cylinder (1000 Track) to the boundary (5007.5 Track), and the servo information written from the outer side and the double written from the innermost cylinder are near the boundary. Servo information is written twice with the servo (another), and the disk on which the servo information is written with a double servo is accepted from the innermost cylinder (10000 Track) to the boundary (5007.5 Track).

  In this case, a gray code “5007” Track is set on the disk 11 as a boundary between servo information written from the outermost cylinder and servo information written from the innermost cylinder. In addition, it is not necessary to write in advance on the inner side with the double servo, and it is only necessary to write in the vicinity of the boundary with the double servo.

  Then, the storage device detects the boundary cylinder information in the received storage medium by reading the servo information written by the second servo writing process with the head (see (1) in (2) of FIG. 1). Specifically, the storage device demodulates the servo information written from the outermost cylinder of the received disk, and detects cylinder information “Gray code“ 5007 ”Track” as a boundary. The gray code “5007” Track serving as the boundary is a defined boundary because the servo information written from the innermost cylinder is overwritten in the vicinity of the boundary. That is, as the user area, the gray code “5007” Track is the boundary from the outer side, and the gray code “5008” Track is the boundary from the inner side.

  Subsequently, in the received storage medium, the storage device reads and detects the boundary cylinder information by the first servo writing process and the servo information not overwritten in the second servo writing process by the head (see FIG. 1 (2) (2)). Specifically, in the above example, the storage device demodulates the servo information written by the double servo from the innermost cylinder and not overwritten by the normal servo in the received disk, and the cylinder information “ Gray code “6007.5” Track ”is detected. Here, the detected gray code “6007.5” Track is track information corresponding to the gray code “5007” Track serving as the boundary detected in (1) of (2) in FIG. User cylinders) indicate the same track number, but the values are not the same due to an environmental change or disturbance of an STW (servo track writer) for writing servo information.

  Here, a method of detecting a double servo near the boundary will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a double servo detection method in the vicinity of the boundary. As shown in (1) of FIG. 2, the storage device normally reads and demodulates servo information at intervals of ServoGate (SG) to control the head. However, since the SG interval is usually the same as the interval of normal servo (normal servo information that is not double servo), servo information written by double servo cannot be read. Therefore, as shown in FIG. 2 (2), the storage device seeks to the vicinity of the boundary by the servo written from the outer side near the boundary, and doubles SG at the boundary to the outer side, so that the outer side In addition to the servo information written from (normal servo), servo information written from the inner side and not overwritten on the outer side (double servo) can be read and demodulated.

  Then, the storage device extracts a difference obtained by subtracting the cylinder information detected using the servo information written from the outermost cylinder from the cylinder information detected using the servo information written from the innermost cylinder ( (See (3) in (2) of FIG. 1). Specifically, in the above example, the storage device uses the servo information written from the outermost cylinder from the gray code “6007.5” Track detected using the servo information written from the innermost cylinder. Then, the difference “1000.5” obtained by subtracting the detected gray code “5007” Track is extracted.

  After that, when the head is on-track to the inner track from the boundary that is a predetermined cylinder, the storage device reads the servo information obtained by adding the difference extracted to the on-track position using the head, The position of the head is controlled using the read servo information (see (2) (4) in FIG. 1).

  Specifically, in the above-described example, since the servo information is a continuous numerical value as the user area, “5008 Track, 5009 Track,...” On the inner side from the detected boundary “5007” Track. It has become. Since the servo information written from the outer side is not written after “5007” Track, it is necessary to demodulate the servo information written from the inner side to control the position of the head. However, as calculated in (3) of (2) in FIG. 1, there is a deviation of “1000.5” in the servo information written on the inner side and the outer side. Therefore, for example, when the head is on-tracked on “5008” Track as the user area, it is necessary to demodulate the servo information “6008.5” Track written from the inner side. In other words, the storage device reads and demodulates the servo information obtained by adding the difference “1000.5” to the servo information as the user area when the head is on-tracked from the gray code “5007” Track serving as the boundary. Control the position of the head.

  As described above, the storage device according to the first embodiment rereads the difference between the outer side and the inner side even in a storage medium in which servo information is written from both the outer side and the inner side using both STWs. As a result of being able to detect accurate servo information, as described above, it is possible to correctly detect the boundary cylinder even in a storage medium with one head, and prevent deterioration of servo quality. It is.

[Configuration of storage device]
Next, the configuration of the storage device shown in FIG. 1 will be described with reference to FIG. FIG. 3 is a block diagram illustrating the configuration of the storage device according to the first embodiment. As shown in FIG. 3, the storage device 10 includes a disk 11, a head 12, a VCM (voice control motor) 13, an RDC (read / write channel) 20, a RAM 30, an SVC (servo controller) 40, An HDC (Hard Disk Controller) 50 and an MCU (Micro Control Unit) 60 are included.

  The disk 11 is subjected to a first servo writing process in which two identical servo information is written in parallel from the inner cylinder to a predetermined cylinder on the outer side. After the first servo writing process, a predetermined value on the inner side from the outermost cylinder is performed. Servo information and user data written in the second servo writing process for writing servo information to the cylinder so as to overwrite one of the two servo information written by the first servo writing process. Record. In this embodiment, the innermost cylinder is described as gray code “10000 Track”, and the outermost cylinder is described as gray code “1000 Track”.

  Specifically, the disk 11 is a disk in which a magnetic film is formed on a metal or glass disk-shaped substrate, is a medium for recording user data and servo information magnetically, and is an innermost cylinder. From the gray code (10000 Track) to the boundary (5007 Track) that is a predetermined cylinder, the same two servo information is written in parallel, and one servo information of two servo information written from the innermost cylinder is overwritten. In the storage medium, one piece of servo information is written from the outermost cylinder, the gray code (1000 Track) to the boundary.

  For example, as illustrated in FIG. 4, the disk 11 stores “ServoFrame” including “PreAmble, SM, Frame, Graycode, burst information” as servo information. Here, the user data is data used for processing in the host computer 100, and the servo information is data used for positioning control of the head 12. The disk 11 is read by the head 12 with the recorded data (user data and servo information) and the data (user data) is written. In this example, the disk 11 has a gray color as a boundary between servo information written from the outermost cylinder track by the first servo writing process and servo information written from the innermost cylinder track by the second servo writing process. Code “5007” Track is set. In other words, on this disk 11, one servo information is written from the outermost cylinder and two identical servo information are written in parallel from the innermost cylinder with the gray code “5007” Track as a boundary. FIG. 4 is a diagram illustrating an example of servo information to be written.

  The head 12 reads / writes data from / to the disk 11 and reads servo information stored in the disk. Specifically, the head 12 is formed of an element that converts magnetism into an electric signal, and reads / writes data and reads servo information while flying above the rotating disk 11. For example, the head 12 reads user data and servo information magnetically recorded on the disk 11 and transmits the data converted into an electrical signal to the RDC 20 via a head amplifier (not shown).

  Here, in order for the head 12 to read or write user data at a predetermined position on the disk 11, positioning control of the head 12 is performed so that the head 12 is positioned at a predetermined position on the disk 11. Need to be Such positioning control of the head 12 is realized by the VCM 13, the SVC 40 and the MCU 60.

  The VCM 13 controls the positioning of the head 12. Specifically, the VCM 13 is a motor that operates a disk drive unit that moves the head, and performs positioning control of the head 12 by rotating the motor. The VCM 13 is connected to the SVC 40 and controlled by the MCU 60.

  The RDC 20 mainly performs code demodulation of user data and servo information read from the disk 11, and also performs code modulation of user data written to the disk 11. Specifically, the RDC 20 includes a modulation circuit for writing user data to the disk 11 and a demodulation circuit for extracting position information on the disk from servo information.

  The RAM 30 temporarily stores data. Specifically, the RAM 30 is a random access memory that is connected to the MCU 60 and temporarily stores read data such as servo information.

  The SVC 40 mainly drives and controls a spindle motor (SPM) and a VCM 13 (not shown). Specifically, the SVC 40 includes a power circuit that drives a spindle motor that is a motor for rotating the disk 11, a power circuit that drives a VCM 13 that controls the positioning of the head 12, and the like. Are connected to the VCM 13, the HDC 50, and the MCU 60. For example, the SVC 40 receives an input of a control value indicating head position control information from the MCU 60 and controls the VCM 13 based on the control value.

  The HDC 50 mainly performs interface control between the host computer 100 and the storage device 10 and interface control of each functional unit. Specifically, the HDC 50 includes an error correction circuit that corrects an error in data transferred between the host computer 100 and the storage device 10, an interface between the host computer 100 and the storage device 10, An interface control circuit that controls an interface between the MCU 60 and the like is provided, and is connected to the host computer 100, the SVC 40, the RDC 20, and the MCU 60.

  For example, when the HDC 50 receives a data read / write instruction from the host computer 100, the HDC 50 transmits the data to the RDC 20 to write data or transmits the data to the host computer 100. Further, for example, the HDC 50 receives a current supplied to the head 12 for position control from the RDC 20 and outputs the current to the MCU 60 described later.

  The MCU 60 has an internal memory for storing a program that defines various processing procedures and necessary data, and mainly performs control of the entire storage device 10 and positioning control of the head 12, and particularly in the present invention. Closely related components include an outer side boundary detection unit 61, an inner side boundary detection unit 62, a difference extraction unit 63, a head position control unit 64, and a rejection unit 65. However, the outer side boundary detection unit 61, the inner side boundary detection unit 62, the difference extraction unit 63, the head position control unit 64, and the rejection unit 65 are not necessarily stored in one MCU. It may be divided into circuits.

  The outer side boundary detection unit 61 detects the track information that becomes the boundary in the received disk 11 by reading the servo information written by the second servo writing process with the head. A specific example will be described. On the disk 11, two parallel servo information (double servo) is written from the innermost cylinder with the gray code (5007) Track as a boundary, and one servo information of the double servo is recorded. One servo information (normal servo) is written from the outermost cylinder so as to overwrite.

  Then, the outer side boundary detection unit 61 outputs an instruction to control the head to a cylinder that becomes a predetermined boundary to the SVC 40, and the SVC 40 drives the VCM 13 as instructed to make the cylinder that makes the head 12 a boundary. On track. Subsequently, the head 12 reads the servo information written by the on-track second servo writing process and outputs the servo information to the RDC 20. The RDC 20 demodulates the input servo information, and the demodulated data is transferred to the HDC 50. To the outer side boundary detection unit 61. After that, the outer side boundary detection unit 61 detects cylinder information “gray code“ 5007 ”Track” as a boundary from the demodulated and inputted information, and extracts the extracted gray code “5007” Track, which will be described later. To the unit 63. The gray code “5007” Track serving as the boundary is a defined boundary because the servo information written from the innermost cylinder is overwritten in the vicinity of the boundary.

  The inner side boundary detection unit 62 reads out and detects the cylinder information that becomes the boundary in the received disk 11 by the head 12 by reading the servo information written by the first servo writing process and not overwritten by the second servo writing process. . Specifically, in the example described above, the inner side boundary detection unit 62 instructs the SVC 40 to control the position of the head, and then the head 12 performs read as in the method described in the outer side boundary detection unit 61. The servo information thus received is received via the RDC 20 and the HDC 50.

  And the inner side boundary detection part 62 is written by the double servo by the first servo writing process from the innermost cylinder of the disk 11 and is not overwritten by the normal servo written by the second servo writing process from the outermost cylinder. Servo information “SV0 (double), etc.” is demodulated to detect the cylinder information “Gray code“ 6007.5 ”Track” as a boundary, and the extracted gray code “6007.5” Track is difference-extracted later. To the unit 63. Here, the detected gray code “6007.5” Track is cylinder information corresponding to the gray code “5007” Track serving as the boundary detected by the outer side boundary detection unit 61, and is used as a user area (User cylinder). Indicate the same track number, but the values are not the same due to an environmental change or disturbance of an STW (servo track writer) for writing servo information.

  The difference extraction unit 63 extracts a difference obtained by subtracting the cylinder information detected by the outer side boundary detection unit 61 from the cylinder information detected by the inner side boundary detection unit 62. Specifically, the difference extraction unit 63 uses the gray code “6007.5” Track input from the inner side boundary detection unit 62 and the gray code “5007” input from the outer side boundary detection unit 61. The difference “1000.5” obtained by subtracting “Track” is extracted, and the extracted difference is output to the head position control unit 64 described later. When the difference obtained by subtracting the cylinder information detected by the outer side boundary detection unit 61 from the cylinder information detected by the inner side boundary detection unit 62 becomes a “negative value”, the difference extraction unit 63 , The rejection unit 65 to be described later is notified that the difference has become a “negative value”.

  The head position control unit 64 uses the head 12 to add servo information obtained by adding the difference extracted by the difference extraction unit 63 to the on-track position when the head 12 is on-tracked on the inner track from the boundary. The position of the head 12 is controlled using the read servo information.

  More specifically, in the above example, when the head 12 is on-tracked to the outer side of the gray code “5007” track as the boundary, only servo information written from the outermost cylinder (gray code “1000” track) exists. In addition, since continuous servo information is written from the outermost cylinder to the boundary gray code “5007” Track, the head position control unit 64 demodulates the servo information written from the outermost cylinder. Based on the obtained information, the position of the head 12 is controlled by controlling and driving the SVC 40 and the VCM 13.

  On the other hand, when the head 12 is on-tracked to the inner side of the gray code “5007” track as the boundary, only servo information written from the innermost cylinder (gray code “10000” track) exists, Since there is a deviation of “1000.5” in the servo information written on the outer side, the numerical value from the boundary (gray code “5007” Track) to the innermost cylinder is not continuous. . For example, the servo information corresponding to “5010” Track in the user area is “6010.5” Track. That is, when the head is on-tracked to “5010” Track in the user area, the servo information to be read is “6010.5” Track instead of “5010” Track. Therefore, when the head is on-tracked to the inner side of the gray code “5007” Track serving as the boundary, the head position control unit 64 detects the difference “1000.5” extracted by the difference extraction unit 63 in the servo information as the user area. The position of the head 12 is controlled by reading and demodulating the servo information “Gray code“ 6007.5 ”Track” obtained by adding.

  When the difference extracted by the difference extraction unit 63 is a negative value, the reject unit 65 informs the outside of the host or the manufacturing facility that the track information in which the negative value is detected exists. Notice. Then, the storage medium is rejected so as not to be used. If the drive has a medium discharge function, it may be discharged and notified to the outside.

  More specifically, when the difference obtained by subtracting the track information detected by the outer side boundary detection unit 61 from the track information detected by the inner side boundary detection unit 62 becomes a “negative value”, There will be a heavy cylinder. In the above example, when the difference becomes “−1000” obtained by subtracting the gray code input from the outer side boundary detection unit 61 from the gray code input from the inner side boundary detection unit 62, the boundary “5007Track” To “4007 Track” are present on both the outer side and the inner side from the boundary. For this reason, when searching for any track from “5007 Track” to “4007 Track”, the outer side and the inner side exist, and therefore, the search cannot be performed correctly. Therefore, when the difference extracted by the difference extraction unit 63 is a negative value, the reject unit 65 rejects the storage medium in which the track information in which the negative value is detected exists.

[Processing by storage device]
Next, boundary detection processing by the storage device will be described with reference to FIG. FIG. 5 is a flowchart illustrating the flow of the boundary detection process in the storage device according to the first embodiment.

(Boundary detection process flow)
As shown in FIG. 5, when a boundary cylinder detection start instruction serving as a boundary is input from the host computer 100 or the like (Yes in step S501), the storage device 10 seeks the head 12 to the boundary cylinder serving as the outer boundary. (Step S502).

  As a specific example, when an instruction to start detection of a cylinder serving as a boundary is input from the host computer 100 or the like, the MCU 60 of the storage device 10 drives the SVC 40 or VCM 13 to form a boundary cylinder serving as an outer boundary. Seek the head 12. Here, the information on the boundary on the outer side is set in the MCU 60 in advance by an administrator or the like, and the storage device 10 that has received a storage cylinder input and has received a boundary cylinder detection start instruction is headed to the boundary cylinder by the MCU 60. 12 can be sought.

  When servo information in the boundary cylinder is read by the head 12 and demodulation is completed (Yes in step S503), the storage device 10 detects cylinder information from the servo information read and demodulated (step S504).

  As a specific example, the head 12 that is seeked by the boundary cylinder and is on-tracked reads the servo information that has been on-tracked and outputs it to the RDC 20, and the RDC 20 demodulates the input servo information to To the MCU 60. The outer boundary detection unit 61 of the MCU 60 that has received this data detects the cylinder information “gray code“ 5007 ”Track” from the received data and outputs it to the difference extraction unit 63.

  Subsequently, the storage device 10 sets the servo mark detection pattern for double servo and seeks the head 12 to the boundary cylinder which becomes the boundary on the inner side (step S505), and the servo information in the boundary cylinder is read by the head 12. When the demodulation is completed (Yes at step S506), the storage device 10 detects (acquires) cylinder information from the servo information read and demodulated (step S507).

  As a specific example, the servo mark detection pattern is set for double servo, and the head 12 that has been sought by the boundary cylinder serving as the boundary on the inner side and is on-tracked reads the servo information that has been on-tracked to read the RDC 20 The RDC 20 demodulates the input servo information and outputs the demodulated servo information to the MCU 60 via the HDC 50. Then, the inner boundary detection unit 62 of the MCU 60 that has received this data detects the cylinder information “gray code“ 6007.5 ”Track” from the received data, and outputs it to the difference extraction unit 63.

  Thereafter, the servo mark detection pattern is set for normal servo (step S508), and when servo information for one round is acquired (Yes in step S509), the storage device 10 calculates the difference in the boundary cylinder (step S510). .

  Specifically, when the servo mark detection pattern is set for normal servo and servo information for one round is acquired, the difference extraction unit 63 of the storage device 10 receives the boundary received from the inner side boundary detection unit 62. A difference “1000.5” obtained by subtracting the boundary cylinder information “gray code“ 5007 ”Track” received from the outer side boundary detection unit 61 is extracted from the cylinder information “gray code“ 6007.5 ”Track”, and this is extracted. This is notified to the head position controller 64.

(Flow of head position control processing)
Next, the head position control process by the storage device will be described with reference to FIG. FIG. 6 is a flowchart illustrating the flow of the head position control process in the storage device according to the first embodiment.

  As shown in FIG. 6, when the seek operation is started (Yes at Step S601), the storage device 10 starts the seek operation as it is when the seek destination is on the outer side from the boundary cylinder (Yes at Step S602). (Step S603), the head 12 is made to reach the target track (Step S605).

  On the other hand, if the seek destination is not on the outer side of the boundary cylinder, that is, if the seek destination is on the inner side of the boundary cylinder (No in step S602), the storage device 10 rereads the difference extracted by the difference extraction unit 63. (Step S604) A seek operation is started (Step S603), and the head 12 is made to reach the target track (Step S605).

  Specifically, in the above example, when the seek destination is on the outer side of the boundary cylinder “5007Track”, for example, the seek destination is “5000Track”, the head position control unit 64 of the storage device 10 performs the seek operation as it is. Is started (step S603), and the head 12 reaches the target track.

  On the other hand, when the seek destination is on the inner side of the boundary cylinder “5007 Track”, for example, the seek destination is “6010 Track”, the head position control unit 64 of the storage device 10 uses the difference “1000” extracted by the difference extraction unit 63. .5 Track ”is read, that is, the seek destination is changed from“ 6010 Track ”to“ 7010.5 Track ”, and the head 12 reaches the target track.

[Effects of Example 1]
As described above, according to the first embodiment, the first servo writing process for writing two identical servo information in parallel from the inner cylinder toward the predetermined cylinder on the outer side is performed. The second servo write process is performed to write servo information so that one servo information of two servo information written by the first servo write process is overwritten from the first servo to the predetermined cylinder on the inner side. The disk 11 in which servo information is written redundantly in a predetermined cylinder by the writing process and the second servo writing process, the head 12 for reading the information written in the disk 11, and the predetermined cylinder information in the disk 11 Servo information written by two servo writing process is read and detected by the head 12 Further, in the disk 11, predetermined cylinder information is written by the first servo writing process and servo information not overwritten in the second servo writing process is read and detected by the head 12, and the cylinder detected from the inner side is detected. Servo that extracts the difference obtained by subtracting the cylinder information detected from the outer from the information and adds the extracted difference to the on-track position when the head is on-track to the track on the inner side of the predetermined cylinder Since the information is read using the head 12 and the position of the head 12 is controlled using the read servo information, the cylinder serving as the boundary can be correctly detected and the servo quality can be deteriorated even in a storage medium having one head. It is possible to prevent. In addition, since the disk 11 with high servo quality can be used, it is possible to contribute to the high TPI of the disk 11.

  Further, according to the first embodiment, when the extracted difference is a negative value, the disk 11 in which the cylinder information in which the negative value is detected is rejected, so the storage medium in which the double cylinder exists Can be detected. As a result, it is possible to eliminate inconveniences that occur when a double cylinder exists, for example, the track number searched from the outer side is different from the track number searched from the inner side.

  In the first embodiment, the case where the servo information is read by obtaining the difference between the normal servo written from the outer side and the double servo written from the inner side in the vicinity of the boundary has been described. However, the servo information can also be read by calculating the relative eccentricity generated by writing the servo information from each of the outer side and the inner side.

[Outline of Storage Device According to Second Embodiment]
Thus, in the second embodiment, a case where the relative eccentricity is further calculated and the servo information is read will be described with reference to FIGS. FIG. 7 is a diagram for explaining the outline of the storage device according to the second embodiment.

  First, the relative eccentricity will be described. When servo information is written in both directions STW, there is a boundary between the servo written from the outer side and the servo written from the inner side. This boundary is not exactly the same due to environmental changes during the STW, and shifts in the time direction and the radial direction, so that there is a high possibility that servo will not be detected or erroneously detected. Therefore, as described in the first embodiment, the boundary is corrected using the double servo near the boundary.

  However, when performing both-direction STW, writing is performed from the inner side and the outer side, but the writing time is shifted at the boundary portion. For this reason, a temperature difference at the boundary write occurs even in a temperature-controlled state. Due to this temperature difference, the arm length slightly changes, and the eccentricity shifts. As a result, relative eccentricity occurs. If there is relative eccentricity, the target position and the actual position will deviate if the boundary is crossed during the Seek, and the Seek current will be violated by overcorrection. For this reason, correction of relative eccentricity is important for using the two-way STW in the apparatus.

  Next, an example in which the relative eccentricity is further calculated and the head is controlled by rereading the servo information will be described with reference to FIG. As described in the first embodiment, at the boundary (5007Track), there is a deviation between the normal servo (5007Track) written from the outer side and the double servo (6007.5Track) written from the inner side. Further, the arm length of the head changes due to a temperature change at the time of servo information writing, and as shown in FIG. 7, a normal servo (5007Track) written from the outer side and a double servo (6007.5Track) written from the inner side are provided. ) Between the normal servo written from the outer side and the double servo written from the inner side does not necessarily match “1000.5” Track. As a specific example, when a double servo is read at time “t”, the servo information becomes “Z (eg, 6007.9)” instead of “6007.5” Track. That is, even if the same servo information is read, the servo information read out varies depending on the time.

  Therefore, the storage device 10 measures cylinder information in each servo frame of the normal servo and the double servo in the boundary cylinder, and performs DFT (Discrete Fourier Transform) on the measured value to obtain the Sin component and the Cos component. The relative eccentricity of these Sin component and Cos component is calculated, and the head is controlled by replacing the calculated relative eccentricity.

  Specifically, the outer side boundary detection unit 61 of the storage device 10 detects the gray code “5007Track” that is a boundary cylinder in the disk 11 by reading the normal servo written on the outer side with the head 12. To do. Subsequently, the inner side boundary detecting unit 62 of the storage device 10 detects the gray code that becomes the boundary in the disk 11 by reading the double servo written on the inner side with the head 12. Then, the difference calculation unit 63 calculates a difference between the cylinder information read by the outer side boundary detection unit 61 and the cylinder information read by the inner side boundary detection unit 62. The storage device 10 detects a normal servo by the outer-side boundary detection unit 61, detects a double servo by the inner-side boundary detection unit 62, and extracts a difference between the vicinity of the boundary (5007Track on the outer side, inner side In this case, it is performed for one week of 6007.5 tracks).

  Then, the difference extraction unit 63 of the storage device 10 performs the above-described method for one week of the track near the boundary, so that the difference for one week associated with each detection time (“Pos (x): x = 0, 1, 2, 3,. Therefore, the difference extracting unit 63 performs frequency analysis (DFT) on the obtained difference values for one week, thereby obtaining “Z” as a function representing servo information including the relative eccentricity (solid line (A) shown in FIG. 7). = Asinθ + Bcosθ ”. The storage device 10 stores only “A” and “B” that are variables unique to the storage device among the calculated functions, and “θ” is positioning information stored in a general storage device. , So there is no need to memorize it.

  Thereafter, the head position controller 64 of the storage device 10 obtains the relative eccentricity from the calculated “Z = Asin θ + B cos θ” when the head 12 crosses the boundary, that is, when servo information on the inner side of the boundary is read. The position of the head 12 is controlled by rereading the obtained amount of relative eccentricity. For example, when the head is on-track to the servo information “5010” Track on the inner side of the boundary, the head position control unit 64 obtains the relative eccentricity amount “1000.8” from the calculated “Z = Asin θ + B cos θ”. The position of the head 12 is controlled using servo information of “6010.8” Track obtained by rereading the relative eccentricity. Thus, the position of the head 12 can be controlled more accurately by obtaining the relative eccentricity amount and rereading the obtained relative eccentricity amount.

[Flow of Processing (Example 2)]
Next, a processing flow according to the second embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a flowchart illustrating a flow of relative eccentricity calculation processing in the storage device according to the second embodiment. FIG. 9 is a flowchart illustrating a flow of head position control processing in the storage device according to the second embodiment.

(Relative eccentricity calculation processing flow)
As shown in FIG. 8, when a relative eccentricity calculation start instruction in the vicinity of the boundary is input from the host computer 100 or the like (Yes in step S801), the storage device 10 moves the head 12 to the boundary cylinder serving as the outer boundary. Seek (step S802).

  As a specific example, when a relative eccentricity calculation start instruction in the vicinity of the boundary is input from the host computer 100 or the like, the MCU 60 of the storage device 10 drives the SVC 40 or VCM 13 to become the outer boundary. Seek the boundary cylinder head 12. Here, the information on the boundary on the outer side is set in the MCU 60 in advance by an administrator or the like, and the storage device 10 that has received a storage cylinder input and has received a boundary cylinder detection start instruction is headed to the boundary cylinder by the MCU 60. 12 can be sought.

  Then, when servo information in the boundary cylinder is read by the head 12 and demodulation is completed (Yes in step S803), the storage device 10 acquires cylinder information (Position) from the servo information read and demodulated (step S804). .

  As a specific example, the head 12 that is seeked by the boundary cylinder and is on-tracked reads the servo information that has been on-tracked and outputs it to the RDC 20, and the RDC 20 demodulates the input servo information to To the MCU 60. The outer boundary detection unit 61 of the MCU 60 that has received this data detects the cylinder information “gray code“ 5007 ”Track” from the received data and outputs it to the difference extraction unit 63.

  Subsequently, the storage device 10 sets the servo mark detection pattern for double servo and seeks the head 12 to the boundary cylinder which is the inner boundary (step S805), and the servo information in the boundary cylinder is read by the head 12. When the demodulation is completed (Yes at step S807), the storage device 10 acquires cylinder information from the servo information read and demodulated (step S808).

  As a specific example, the servo mark detection pattern is set for double servo, and the head 12 that has been sought by the boundary cylinder serving as the boundary on the inner side and is on-tracked reads the servo information that has been on-tracked to read the RDC 20 The RDC 20 demodulates the input servo information and outputs the demodulated servo information to the MCU 60 via the HDC 50. Then, the inner boundary detection unit 62 of the MCU 60 that has received this data detects the cylinder information “Gray code“ 6007.7 ”Track from the received data and outputs it to the difference extraction unit 63.

  Thereafter, the servo mark detection pattern is set for normal servo (step S809), and when servo information for one round is acquired (Yes in step S810), the storage device 10 calculates the relative eccentricity (step S811).

  Specifically, when the servo mark detection pattern is set for normal servo and servo information for one round is acquired, the difference extraction unit 63 of the storage device 10 receives the boundary received from the inner side boundary detection unit 62. A difference “1000.5” obtained by subtracting the boundary cylinder information “gray code“ 5007 ”Track” received from the outer side boundary detection unit 61 is extracted from the cylinder information “gray code“ 6007.7 ”Track”. By performing the above-described series of flows, the difference extraction unit 63 sets “1000.4”, “1000.5”, “1000.7”, “1000.8”. ”,“ −1000.7 ”,“ −1000.6 ”,“ −1000.5 ”..., And the like, and a function“ Z = Asin θ + B cos θ ”representing relative eccentricity is obtained from these.

(Flow of head position control processing)
Next, the head position control process by the storage device according to the second embodiment will be described with reference to FIG. FIG. 9 is a flowchart illustrating the flow of the head position control process in the storage device according to the second embodiment.

  As shown in FIG. 9, the seek operation is started (Yes at Step S901), and the storage device 10 demodulates the servo information that the head 12 is on-track (Step S902), and the servo information (position of the head 12) is It is determined whether the inner side or the outer side from the boundary (step S903).

  As a specific example, the head position control unit 64 of the storage device 10 seeks the head 12, demodulates the servo information that the head 12 is on-track, and the position of the head 12 is the boundary (“5007” Track). ) To determine whether it is the inner side or the outer side.

  If the position of the head 12 is on the inner side of the boundary (Yes at Step S903), the storage device 10 calculates the relative eccentricity of the servo sector (Step S904), and rereads the relative eccentricity (Step S905). Seek control is performed (step S906).

  Specifically, when the position of the head 12 is determined to be “5010” Track on the inner side of the boundary (“5007” Track), the storage device 10 uses the calculated function “Z = Asin θ + B cos θ”. The relative eccentricity is calculated (for example, 1000.4), and seek control is performed using servo information (6010.4) obtained by replacing the relative eccentricity (1000.4).

  On the other hand, when the position of the head 12 is on the outer side from the boundary (No at Step S903), the storage device 10 performs seek control on the position of the head 12 as it is (Step S906).

  Then, the storage device 10 determines whether or not the seek has been completed (step S907). If the seek has been completed (Yes in step S907), the process is terminated, and if the seek has not been completed (No in step S907). Returning to step S902, the processing from step S902 onward is executed.

[Effects of Example 2]
As described above, according to the second embodiment, in the vicinity of the boundary, not only the difference between the double servo written from the inner side and the normal servo written from the outer side, but also the servo information from both the inner side and the outer side. The position of the head 12 is controlled by using the servo information obtained by rewriting the calculated amount of relative eccentricity by reading the calculated amount of relative eccentricity. Therefore, the position of the head 12 can be controlled more accurately. it can.

  Further, according to the second embodiment, it is possible to prevent an abnormal current from flowing due to overcorrection when the head 12 seeks. For example, as shown in FIG. 10, in the case of (2) in which the relative eccentricity is corrected in the VCM current and Pos (Position) at the time of seek across the boundary, the relative eccentricity is not corrected (1 It can be seen that it is more stable than the case of). In particular, in the cylinder having the maximum relative eccentricity, the VCM current and Pos (Position) in the case of (2) in which the relative eccentricity is corrected are more stable. That is, it is possible to prevent an abnormal current from flowing due to overcorrection when the head 12 seeks. FIG. 10 is a diagram for explaining an example of an abnormal current due to overcorrection during seek.

  In the second embodiment, the case has been described in which the function representing the relative eccentricity is obtained after calculating the difference for one week of the track near the boundary (5007Track), but the present invention is not limited to this. It is also possible to obtain a function representing the relative eccentricity after calculating several differences in the track near the boundary (5007Track).

  In the second embodiment, the case where the head position is controlled using servo information obtained by replacing the calculated relative eccentricity amount has been described. However, the present invention is not limited to this, and the calculated relative eccentricity amount is described. Extracting the difference between the servo information (final target position) that has been read in minutes and the estimated position of the estimated head, and controlling the head position to reach the final target position by gradually replacing the difference You can also.

[Outline of Storage Device According to Embodiment 3]
Therefore, in the third embodiment, the difference between the actual position of the head and the estimated position is extracted using FIGS. 11 and 12, and the position of the head is changed to the target position by gradually reading the difference. The case of controlling to reach will be described. FIG. 11 is a diagram for explaining the outline of the storage device according to the third embodiment.

  The storage device 10 includes an estimator that estimates a head position from a current supplied to a head 12 that is generally used in a magnetic disk device or the like. Then, the storage device 10 calculates a function “Z = Asin θ + B cos θ” that represents the relative eccentricity of the inner double servo by using the same method as in the second embodiment, and recalculates this function by recalculating the time component into the frequency component. The relative eccentricity “Z (for example, 6007Track)” is obtained by using this.

  Then, the storage device 10 extracts a difference between the relative eccentricity “Z (for example, 6007Track)” that is the calculated final target position and the estimated position of the head 12 estimated by the estimator, and a ratio (100 %) Is added to the final target position as a target position, and the current value supplied to the head 12 is slightly changed to control the position. Subsequently, the storage device 10 extracts a difference between the final target position and the estimated position estimated by the estimator, multiplies the difference by a ratio (90%), and adds the value to the final target position as a target position. The position is controlled by changing the current value supplied to 12 by a small amount. In this way, the difference between the final target position and the estimated position estimated by the estimator is extracted, the value obtained by multiplying the difference by the ratio (100% to 0%) and added to the final target position is set as the target position. By controlling stepwise, the head 12 is gradually brought closer to the final target position “6007Track”.

[Processing in Example 3]
Next, a processing flow in the storage device according to the third embodiment will be described with reference to FIG. FIG. 12 is a flowchart illustrating the flow of seek processing in the storage device according to the third embodiment.

  As shown in FIG. 12, when seek control is started (Yes at Step S1201), the storage device 10 demodulates the servo information that the head 12 is on-track (Step S1202), and whether the head 12 straddles the boundary. It is determined whether or not (step S1203).

  As a specific example, the head position control unit 64 of the storage device 10 seeks the head 12, demodulates the servo information that the head 12 is on-track, and the position of the head 12 is the boundary (“5007” Track). ) Determine whether you have crossed.

  When the position of the head 12 crosses the boundary (Yes at Step S1203), the storage device 10 calculates the difference between the actual position and the estimated position (Step S1204).

  Specifically, when the position of the head 12 crosses the boundary (“5007” Track), the difference extraction unit 63 of the storage device 10 determines the relative eccentricity “Z (for example, 6007 Track)” that is the final target position. And the difference between the calculated final target position and the estimated position estimated by the estimator is extracted and notified to the head position control unit 64.

  Thereafter, the storage device 10 calculates the target position (step S1205), performs seek control on the calculated target position (step S1206), changes the ratio used to calculate the target position (step S1207), and changes the target position. Until the obtained ratio becomes “0%” (No in step S1308), the process returns to step S1205 to calculate the target position, and seek control of the head 12 is performed.

  As a specific example, the head position control unit 64 of the storage device 10 multiplies the difference received from the difference extraction unit 63 by the ratio (100%) and adds it to the final target position, and the head 12 is set as the target position. Control. Thereafter, the head position control unit 64 extracts a difference between the final target position and the estimated position estimated by the estimator, and multiplies the difference by a ratio (100% to 0%) to add the value to the final target position. The head 12 is gradually brought closer to the final target position “6007Track” by changing the current supplied to the head 12 as a target position by a minute amount and controlling the position stepwise. It should be noted that the ratio at which the ratio is changed can be arbitrarily set by an administrator or the like.

  When the changed ratio becomes “0%” (Yes at Step S1208), that is, when the head reaches the final target position, the head position control unit 64 ends the seek control (Step S1209).

  On the other hand, returning to step S1203, if the head 12 does not straddle the boundary (No at step S1203), the storage device 10 performs seek control (step S1210), and repeats the processing after step S1102.

[Effects of Example 3]
As described above, according to the third embodiment, the difference between the servo information (final target position) obtained by calculating the relative eccentricity amount and replacing the calculated relative eccentricity amount and the estimated head position is extracted. As a result, the head position can be controlled so as to reach the final target position, so that it is possible to firmly prevent abnormal current from flowing due to overcorrection when the head 12 seeks. It is.

  By the way, in the present invention, when the head 12 crosses the boundary, the target position is reached when the control method is changed from coarse control for seek control between a plurality of tracks to fine control for seek control of a delicate position. Thus, the head 12 can be gradually controlled stepwise.

  As a specific example, as shown in FIG. 13, when the head 12 crosses the boundary, the control method is changed from coarse control for seek control between a plurality of tracks to fine control for seek control of a delicate position. In this case, the head 12 can be gradually controlled stepwise so as to reach the target position. FIG. 13 is a diagram for explaining an example in which the head 12 is gradually controlled stepwise when the control method is changed from coarse control to fine control when the head 12 crosses the boundary.

  For example, a case where the estimation is performed using the estimator described in the third embodiment will be described as an example. Here, the multiplication ratio is “80, 60, 40, 20, 0”, and the time for moving the head 12 horizontally with respect to the target position is “0.2 ms”.

  In this case, the storage device 10 extracts the difference between the relative eccentricity “Z (for example, 6007Track)” that is the calculated final target position and the estimated position of the head 12 estimated by the estimator, and the ratio ( 80%) is added to the final target position as a target position, the current value supplied to the head 12 is changed by a small amount to control the position of the head 12, and the same position for “0.2 ms”. Keep

  Thereafter, the storage device 10 extracts a difference between the calculated final target position “Z” and the estimated position of the head 12 estimated by the estimator, and multiplies this difference by a ratio (60%) to add to the final target position. The head 12 is controlled using the obtained value as a target position, and the same position is kept for “0.2 ms”.

  This above-described method is repeated until the ratio becomes “0%”. That is, the storage device 10 extracts the difference between the relative eccentricity “Z (for example, 6007Track)” that is the calculated final target position and the estimated position of the head 12 estimated by the estimator, and multiplies the difference by the ratio. By controlling the head 12 to a predetermined position and shifting the position for a predetermined time, the head 12 is gradually brought closer to the relative eccentricity “Z (for example, 6007Track)” that is the final target position in a stepwise manner. Can continue. As a result, in order to finely control the position of the head 12, even in fine control in which the current value supplied to the head 12 needs to be changed by a small amount, an abnormal current caused by overcorrection when the head 12 seeks is passed. It is possible to prevent it strongly.

  Although the embodiments of the present invention have been described so far, the present invention may be implemented in various different forms other than the embodiments described above. Therefore, as shown below, (1) detection of the amount of time shift, (2) double servo using a special mark pattern, (3) unused area near the boundary, (4) position of the boundary, (5 ) Different embodiments will be described by dividing them into system configurations.

(1) Detection of time lag amount For example, in the present invention, servo information that is not overwritten in the second servo writing process is used among the double servos in parallel with the same two servo information written in the first servo writing process. As a result, the time lag amount of the servo information written in each of the first servo writing process and the second servo writing process can also be obtained.

  Specifically, as shown in FIG. 14, SV0 (double) is written in the middle of SV0 and SV1, and thus is written at a half of the servo interval. Therefore, by measuring the time between the outer SV0 and the inner SV0 (double), the time difference between the inner SV0 and the outer SV0 can be obtained. In addition, when the time shift measurement is obtained from each servo information in one round, the accuracy can be further increased. FIG. 7 is a diagram illustrating an example of a method for calculating the time shift amount.

(2) Double Servo Using Special Mark Pattern In the first servo writing process, the present invention is a disk in which servo information that is not overwritten by the second servo writing process is written using a special mark pattern. It can also be used. That is, a special mark pattern that is not normally used for servo information that has not been overwritten in the second servo writing process out of double servos in parallel with two identical servo information written in the first servo writing process can be used.

  By doing so, the head position control unit 64 cannot use the servo information written with the special mark pattern for the position control of the head 12, so that the servo information written by the double servo and not overwritten is mistaken. As a result, the servo information that has been written by the double servo and not overwritten can exist in the written state even after data is written to the disk. It is possible to correctly detect the cylinder and prevent deterioration of servo quality.

(3) Making the vicinity of the boundary an unused area In the present invention, in the disk 11, the vicinity of the predetermined cylinder (near the boundary) detected by the outer side boundary detection unit 61 is skipped so as not to be used as a user area. The position of the head 12 can also be controlled. For example, the head position control unit 64 registers two tracks before and after 5007 tracks detected by the outer side boundary detection unit 61 as unused areas in the disk management area, and performs skip control. The position of the head 12 is controlled so as not to be used as a user area.

  As a result, it is possible to prevent data from being written to the boundary cylinder. As a result, the servo information written in the vicinity of the boundary is written even after data is written to the disk 11. Therefore, it is possible to correctly detect the boundary cylinder and prevent the servo quality from deteriorating.

(4) Position of Boundary In the present invention, the disk 11 having a predetermined cylinder as a boundary near the yaw angle of 0 degrees can also be used. Specifically, a first servo writing process is performed in which two identical servo information is written in parallel from the inner cylinder toward a cylinder near the outer side yaw angle of 0 degrees. A second servo writing process for writing servo information to the cylinder near the yaw angle near 0 degrees on the side so as to overwrite one of the two servo information written by the first servo writing process is performed. It is also possible to use a disk 11 in which servo information is written redundantly in a cylinder near an angle of 0 degrees.

  When such a disk is used, the difference in R / WGap increases when the yaw angle is other than 0 degrees, so the area that should not be used also increases. However, for cylinders with a yaw angle of 0 degrees, Read / Write is used. Is performed in the same cylinder, so there are few wasted tracks. As a result, it is possible to prevent the head position from becoming unstable due to a servo mark error or false detection that occurs when the Read core is present at the boundary, or a gray code erroneous detection or burst information erroneous detection. Is possible.

(5) System Configuration The components of the illustrated devices are functionally conceptual and do not necessarily need to be physically configured as illustrated. In the above embodiment, the method realized by the CPU firmware program has been described. However, the present invention is not limited to this, and the present invention is similarly applied to methods realized by other configurations. Can do. That is, the specific form of distribution / integration of each device is not limited to the one shown in the figure (for example, FIG. 2), and all or a part thereof can function in arbitrary units according to various loads and usage conditions. The outer side boundary detection unit 61 and the inner side boundary detection unit 62 may be integrated and configured, for example, in a distributed or integrated manner. Furthermore, all or any part of each processing function performed in each device is performed by the MCU (or a processing device such as a CPU or MPU) and the MCU (or a processing device such as a CPU or MPU). It can be realized by a program to be analyzed and executed, or can be realized as hardware by wired logic.

  The head position control method described in the above embodiment can be realized by being executed by a micro control unit in a disk device as a computer. These programs can be distributed via a network such as the Internet. The program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, a flexible disk (FD), a CD-ROM, an MO, and a DVD and being read from the recording medium by the computer.

(Supplementary note 1) In the vicinity region including the predetermined cylinder, the first servo writing process for writing two identical servo informations in parallel is performed, and one servo among the two servo information written by the first servo writing process is performed. A second servo writing process for writing servo information so as to overwrite information, a storage medium in which servo information is written in duplicate in the predetermined cylinder by the first servo writing process and the second servo writing process;
A head for reading information written in the storage medium;
In the storage medium, a first boundary detection unit that reads and detects the cylinder information of the predetermined cylinder by reading the servo information written by the second servo writing process by the head;
In the storage medium, a second boundary detection unit that reads and detects, by the head, servo information that is written in the first servo writing process and is not overwritten in the second servo writing process in the storage medium. When,
A difference extraction unit for extracting a difference between the cylinder information detected by the first boundary detection unit and the cylinder information detected by the second boundary detection unit;
The on-track position when the head moves and moves between the predetermined cylinder written by the first servo writing process and the predetermined cylinder written by the second servo writing process. A head position control unit that reads the servo information obtained by adding or subtracting the difference extracted by the difference extraction unit using the head, and controls the position of the head using the read servo information;
A storage device comprising:

(Additional remark 2) When the difference extracted by the said difference extraction means is a negative value, the rejection part which notifies outside that it is a storage medium with the cylinder information from which the negative value was detected was provided The storage device according to attachment 1, wherein

(Supplementary Note 3) The storage medium is a storage medium in which servo information that is not overwritten in the second servo write process is written using a special mark pattern in the first servo write process,
The storage device according to appendix 1 or 2, wherein the head position control unit does not use servo information written with the special mark pattern in the storage medium for position control of the head.

(Additional remark 4) The said head position control part controls the position of the said head so that it skips the vicinity of the predetermined | prescribed cylinder detected by the said outer side boundary detection part in the said storage medium, and it does not use as a user area | region. The storage device according to any one of appendices 1 to 3, wherein:

(Supplementary Note 5) The storage medium is subjected to a first servo write process in which two identical servo information is written in parallel from an inner cylinder or an outer cylinder to a cylinder near a yaw angle of 0 degrees, and the yaw angle is 0 degrees from the opposite direction. A second servo write process is performed to write servo information so as to overwrite one of the two servo information written by the first servo write process toward a nearby cylinder, and the first servo write process The storage device according to any one of appendices 1 to 4, wherein servo information is written redundantly in a cylinder near a yaw angle of 0 degrees by the second servo writing process.

(Supplementary Note 6) In the vicinity area including the predetermined cylinder, the first servo writing process for writing two identical servo informations in parallel is performed, and one servo among the two servo information written by the first servo writing process is performed. A second servo writing process for writing servo information so as to overwrite information is performed, and the servo information is overlapped and written to the storage medium in the predetermined cylinder by the first servo writing process and the second servo writing process. Servo information writing method.

(Supplementary note 7) A special mark pattern is used for servo information that is not overwritten in the second servo writing process when servo information is written to a storage medium in the first servo writing process. Servo information writing method.

(Supplementary note 8) The supplementary note 6 or 7, wherein the predetermined cylinder is set to a yaw angle of about 0 degrees, and servo information is written to a storage medium by each of the first servo write process and the second servo write process. Servo information writing method.

(Supplementary note 9) A first servo writing unit for writing two pieces of the same servo information in parallel in a vicinity region including a predetermined cylinder of the storage medium;
A second servo writing unit that writes servo information so as to overwrite one of the two servo information written by the first servo writing unit,
A servo information writing device comprising:

(Supplementary note 10) The servo information writing device according to supplementary note 9, wherein the first servo writing unit uses a special mark pattern for servo information that is not overwritten by the second servo writing unit.

(Supplementary Note 11) The first servo writing unit writes servo information from the inner cylinder or the outer cylinder toward a predetermined cylinder near a yaw angle of 0 degrees,
The second servo writing unit applies the first servo writing unit toward a predetermined cylinder at a yaw angle of about 0 degrees from the reverse direction with respect to the storage medium on which the servo information is written by the first servo writing unit. 11. The servo information writing device according to appendix 9 or 10, wherein the servo information is written so as to overwrite one of the two servo information written.

(Additional remark 12) The said difference detection part extracts the difference of the cylinder information detected by the said 1st boundary detection part and the cylinder information detected by the said 2nd boundary detection part in the several places of the said storage medium The storage device according to attachment 1, wherein

(Supplementary note 13) The head is servo information written in the first servo write process while following predetermined cylinder information on the servo information written in the second servo write process, By reading the cylinder information on the servo information that has not been overwritten by the servo writing process, the difference extraction unit detects the cylinder information detected by the first boundary detection unit and the cylinder detected by the second boundary detection unit. The storage device according to attachment 12, wherein a difference from the information is extracted.

(Supplementary Note 14) In the vicinity region including the predetermined cylinder, a first servo write process is performed in which two identical servo information is written in parallel, and one servo among the two servo information written by the first servo write process. A second servo writing process for writing servo information so as to overwrite information, a storage medium in which servo information is written in duplicate in the predetermined cylinder by the first servo writing process and the second servo writing process; A head for reading information written in the storage medium; and a first boundary for detecting cylinder information of the predetermined cylinder in the storage medium by reading the servo information written by the second servo writing process by the head. And detecting cylinder information of the predetermined cylinder in the storage medium. A second boundary detection step of reading and detecting servo information written by one servo writing process and not overwritten in the second servo writing process, and cylinder information detected by the first boundary detection step; A difference extraction step of extracting a difference from the cylinder information detected by the second boundary detection step, and a seek control method for a storage device,
The on-track position when the head moves and moves between the predetermined cylinder written by the first servo writing process and the predetermined cylinder written by the second servo writing process. A seek control method, wherein servo information obtained by adding or subtracting the difference extracted in the difference extraction step is read using the head, and the head is seeked to a target position using the read servo information.

(Supplementary Note 15) The difference detection step extracts a difference between cylinder information detected by the first boundary detection step and cylinder information detected by the second boundary detection step at a plurality of locations of the storage medium. The seek control method according to supplementary note 14, wherein

(Supplementary Note 16) The head is servo information written in the first servo write process while following predetermined cylinder information on the servo information written in the second servo write process, By reading the cylinder information on the servo information that has not been overwritten by the servo writing process, the difference extracting step includes the cylinder information detected by the first boundary detecting step and the cylinder detected by the second boundary detecting step. 16. The seek control method according to appendix 15, wherein a difference from the information is extracted.

(Supplementary Note 17) The storage device further includes an actuator that supports the head, and a voice coil motor that seeks the actuator by energizing a current.
15. The seek control method according to appendix 14, wherein the current value is changed by a small amount when the target position and the current position do not match during seek.

(Supplementary note 18) The seek control method according to supplementary notes 14 to 17,
Furthermore, the position error is calculated from the target position and the current position,
A seek control method comprising detecting that the vicinity of the target position has been reached, switching to following control, and executing the following control.

(Supplementary note 19) In the vicinity region including a predetermined cylinder, a first servo write process for writing two identical servo informations in parallel is performed, and one servo among two servo information written by the first servo write process On the storage medium in which the servo information is written so as to overwrite the information, the servo information is written redundantly in the predetermined cylinder by the first servo writing process and the second servo writing process. A control circuit for seeking a head for reading information written in the storage medium,
A first boundary detection unit configured to read and detect cylinder information of the predetermined cylinder in the storage medium, servo information written by the second servo writing process, and a head that reads information written to the storage medium; ,
In the storage medium, a second boundary detection unit that reads and detects, by the head, servo information that is written in the first servo writing process and is not overwritten in the second servo writing process in the storage medium. When,
A difference extraction unit for extracting a difference between the cylinder information detected by the first boundary detection unit and the cylinder information detected by the second boundary detection unit;
The on-track position when the head moves and moves between the predetermined cylinder written by the first servo writing process and the predetermined cylinder written by the second servo writing process. A head position control unit that reads the servo information obtained by adding or subtracting the difference extracted by the difference extraction unit using the head, and controls the position of the head using the read servo information;
A control circuit comprising:

(Supplementary Note 20) The difference detection unit extracts a difference between cylinder information detected by the first boundary detection unit and cylinder information detected by the second boundary detection unit at a plurality of locations on the storage medium. Item 20. The control circuit according to Item 19, wherein

(Supplementary note 21) The head is servo information written in the first servo write process while following predetermined cylinder information on the servo information written in the second servo write process, and the second servo write process By reading the cylinder information on the servo information that has not been overwritten by the servo writing process, the difference extraction unit detects the cylinder information detected by the first boundary detection unit and the cylinder detected by the second boundary detection unit. Item 20. The control circuit according to item 19, wherein a difference from the information is extracted.

(Supplementary Note 22) The control circuit is further connected to an actuator that supports the head and a voice coil motor that seeks the actuator by energizing a current.
20. The control circuit according to appendix 19, wherein the current value is changed by a small amount when the target position and the current position do not match during seek.

(Supplementary note 23) The control circuit according to supplementary notes 19-22,
Furthermore, the position error is calculated from the target position and the current position,
A control circuit that detects that the vicinity of the target position has been reached, switches to following control, and executes the following control.

  As described above, the storage device, the servo information writing method, the seek control method, and the control circuit according to the present invention have the storage medium in which the boundary between the servo information written from the inner side and the servo information written from the outer side exists. On the other hand, it is useful for controlling the position of the head that reads and writes data by demodulating the written servo information and acquiring cylinder information. It is suitable for detecting the correct cylinder and preventing the deterioration of servo quality.

1 is a diagram for explaining an overview and characteristics of a storage device according to Embodiment 1. FIG. It is a figure which shows the example of the double servo detection method in the boundary vicinity. 1 is a block diagram illustrating a configuration of a storage device according to Embodiment 1. FIG. It is a figure which shows the example of the servo information written. 3 is a flowchart illustrating a flow of boundary detection processing in the storage device according to the first embodiment. 3 is a flowchart illustrating a flow of head position control processing in the storage device according to the first embodiment. FIG. 6 is a diagram for explaining an overview of a storage device according to a second embodiment. 12 is a flowchart illustrating a flow of relative eccentricity calculation processing in the storage device according to the second embodiment. 12 is a flowchart illustrating a flow of head position control processing in the storage device according to the second embodiment. It is a figure for demonstrating the example of the abnormal electric current by the overcorrection at the time of a seek. FIG. 9 is a diagram for explaining an overview of a storage device according to a third embodiment. 12 is a flowchart illustrating a flow of seek processing in the storage device according to the third embodiment. It is a figure for demonstrating the example which controls gradually the head 12 in step shape when the control method is changed from coarse control to fine control when the head 12 straddles a boundary. It is a figure which shows the example of the method of calculating the time gap | deviation amount. It is a figure which shows the relationship between a yaw angle and the feed direction of STW. It is a figure for demonstrating the erase part in the feed direction of STW. It is a figure which shows the shift | offset | difference of the time direction of the written servo information, and a radial direction.

Explanation of symbols

10 storage device 11 disk 12 head 13 VCM
20 RDC
30 RAM
40 SVC
50 HDC
60 MCU
61 Outer side boundary detection unit 62 Inner side boundary detection unit 63 Difference extraction unit 64 Head position control unit 65 Rejection unit 100 Host computer

Claims (11)

In the vicinity area including the predetermined cylinder, the first servo writing process for writing two identical servo informations in parallel is performed, and one servo information among the two servo information written by the first servo writing process is overwritten. A second servo writing process for writing servo information as described above, and a storage medium in which servo information is written in duplicate in the predetermined cylinder by the first servo writing process and the second servo writing process,
A head for reading information written in the storage medium;
In the storage medium, a first boundary detection unit that reads and detects the cylinder information of the predetermined cylinder by reading the servo information written by the second servo writing process by the head;
In the storage medium, a second boundary detection unit that reads and detects, by the head, servo information that is written in the first servo writing process and is not overwritten in the second servo writing process in the storage medium. When,
A difference extraction unit for extracting a difference between the cylinder information detected by the first boundary detection unit and the cylinder information detected by the second boundary detection unit;
The on-track position when the head moves and moves between the predetermined cylinder written by the first servo writing process and the predetermined cylinder written by the second servo writing process. A head position control unit that reads the servo information obtained by adding or subtracting the difference extracted by the difference extraction unit using the head, and controls the position of the head using the read servo information;
A storage device comprising:   When the difference extracted by the difference extraction means is a negative value, a rejection unit is provided for notifying the outside that the cylinder information in which the negative value is detected is a storage medium. The storage device according to claim 1. In the first servo writing process, the storage medium is a storage medium in which servo information that is not overwritten in the second servo writing process is written using a special mark pattern,
The storage device according to claim 1, wherein the head position control unit does not use servo information written with the special mark pattern in the storage medium for position control of the head.   The head position control unit controls the position of the head in the storage medium so that the vicinity of a predetermined cylinder detected by the outer side boundary detection unit is skipped and is not used as a user area. The storage device according to claim 1.   In the vicinity area including the predetermined cylinder, the first servo writing process for writing two identical servo informations in parallel is performed, and one servo information among the two servo information written by the first servo writing process is overwritten. Servo information writing, wherein servo information is written to a storage medium by overlapping the servo information in the predetermined cylinder by the first servo writing processing and the second servo writing processing. Method.   The difference detection unit extracts a difference between cylinder information detected by the first boundary detection unit and cylinder information detected by the second boundary detection unit at a plurality of locations of the storage medium. The storage device according to claim 1.   The head is servo information written in the first servo write process while following predetermined cylinder information on the servo information written in the second servo write process, and By reading the cylinder information on the servo information that has not been overwritten, the difference extraction unit can detect the difference between the cylinder information detected by the first boundary detection unit and the cylinder information detected by the second boundary detection unit. The storage device according to claim 6, wherein the storage device is extracted. In the vicinity area including the predetermined cylinder, the first servo writing process for writing two identical servo informations in parallel is performed, and one servo information among the two servo information written by the first servo writing process is overwritten. The servo information is written in the second servo writing process, and the first servo writing process and the second servo writing process result in the servo information being written redundantly in the predetermined cylinder, and the storage medium A head for reading out written information; and a first boundary detection step for reading out and detecting the cylinder information of the predetermined cylinder in the storage medium by the head by reading out servo information written by the second servo writing process; In the storage medium, the cylinder information of the predetermined cylinder is recorded in the first servo writing. A second boundary detecting step for reading out and detecting servo information written by the processing and not overwritten in the second servo writing processing, the cylinder information detected by the first boundary detecting step, and the second A difference extraction step for extracting a difference from the cylinder information detected by the boundary detection step, and a seek control method for a storage device,
The on-track position when the head moves and moves between the predetermined cylinder written by the first servo writing process and the predetermined cylinder written by the second servo writing process. A seek control method, wherein servo information obtained by adding or subtracting the difference extracted in the difference extraction step is read using the head, and the head is seeked to a target position using the read servo information. The storage device further includes an actuator that supports the head, and a voice coil motor that seeks the actuator by energizing a current.
9. The seek control method according to claim 8, wherein if the target position does not coincide with the current position at the time of seek, the current value is changed by a small amount. The seek control method according to claim 8 or 9, wherein
Furthermore, the position error is calculated from the target position and the current position,
A seek control method comprising detecting that the vicinity of the target position has been reached, switching to following control, and executing the following control. In the vicinity area including the predetermined cylinder, the first servo writing process for writing two identical servo informations in parallel is performed, and one servo information among the two servo information written by the first servo writing process is overwritten. A second servo writing process for writing servo information as described above, and the storage medium on which the servo information is written redundantly in the predetermined cylinder by the first servo writing process and the second servo writing process. A control circuit that seeks the head for reading the information written in
A first boundary detection unit configured to read and detect cylinder information of the predetermined cylinder in the storage medium, servo information written by the second servo writing process, and a head that reads information written to the storage medium; ,
In the storage medium, a second boundary detection unit that reads and detects, by the head, servo information that is written in the first servo writing process and is not overwritten in the second servo writing process in the storage medium. When,
A difference extraction unit for extracting a difference between the cylinder information detected by the first boundary detection unit and the cylinder information detected by the second boundary detection unit;
The on-track position when the head moves and moves between the predetermined cylinder written by the first servo writing process and the predetermined cylinder written by the second servo writing process. A head position control unit that reads the servo information obtained by adding or subtracting the difference extracted by the difference extraction unit using the head, and controls the position of the head using the read servo information;
A control circuit comprising:

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