JPH0945025A - Disc apparatus and method for measuring shift amount of heads - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a disc apparatus which can measure the shift amount of heads of a dual head with time. SOLUTION: A special area is provided for measuring the shifting amount of heads for every face of media 201 of the disc apparatus. Burst signals are written in adjacent tracks in the area while a read head 108 traces the tracks. Thereafter, when the read head 108 is positioned at the center of the adjacent tracks, a shift of heads is detected from an output difference of the burst signals. A change of the shifting amount with time is measured. Based on the measuring result, an offset of a write head 107 to the read head 108 is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk apparatus having a read head for reading and a separate head having a write head for writing, and more particularly to writing to a read head on a track of a recording medium. A disk device capable of measuring an offset amount between heads, which is the amount of offset of the head in the track width direction, and enabling offset adjustment for correcting the offset between heads, and
The present invention relates to a method for measuring the head-to-head displacement.

[0002]

2. Description of the Related Art In recent years, disk devices have been rapidly reduced in size, increased in speed, enhanced in function, and reduced in price. In particular, the speed of increasing the capacity of magnetic disk devices is rapidly increasing. This is realized by an increase in the number of user data recording media per device and an increase in the amount of user data recorded per unit area of the medium (referred to as areal recording density). Here, the areal recording density has conventionally been increased by about 1.4 times a year. However, since the last 1-2 years, the inclination has become steep with the areal recording density doubled a year. The reason for this is that an increasing number of devices have adopted the dual head system. That is, conventionally, for the data of the medium, one head has been used for both reading and writing of user data. However, recently, a dual head system using a write head suitable for data writing and a read head suitable for reading has been increasing. As a result, it has become possible to realize double the capacity per year.

Generally, a write head is a thin film head and a read head is an MR (Magnetoro Resist).
lance) head is often used. by the way,
In the case of two heads, it is required that the writing in the circumferential direction and the reading center of each head be aligned. However, since the two heads are mechanically manufactured, it is very difficult to center them. Therefore, it is necessary to realize positioning such that each head passes through the center of the data storage track in the circumferential direction at the time of writing and reading data.

The current assembly accuracy of the read head and the write head is ± 1 μm when the center of each head is displaced.
Degree. The current track density is 5000T.
Since it is about PI (Track Per Inch), the track interval is about 5 μm. The accuracy with which data can be read and written is beak-to-peak with respect to the circumferential center of the corresponding track.
It is said that it is within about 5% of the track interval, 0.25
The accuracy of μmpp is required. By the way, since the deviation amount between the centers of the read head and the write head is about ± 1 μm as described above, in order to position the read head and the write head at the center of the track in the circumferential direction to be accessed, Read head and write head respectively
It must be centered in the circumferential direction of the track.

For this positioning, it is necessary to give a deviation correction value. Therefore, conventionally, the deviation correction value is obtained by measuring the deviation amount in advance at the time of factory shipment, and the deviation correction value is stored in a non-volatile portion such as a ROM, a FLASH memory, or another storage medium of the disk device. I'll do it.
As a result, according to the operation at the time of reading or writing data of a normal disk device, the stored correction value is used to realize offset positioning by the amount of shift between the heads with respect to the center of the track in the circumferential direction. This allows the head to be used to be positioned at the center of the track.

Incidentally, in the case of a small magnetic disk device, a rotary actuator is usually used for positioning the head. In this case, since the rotation angles of the head with respect to the inner and outer tracks are different, the amounts of misalignment between the read head and the write head in the circumferential direction are different between the inner and outer tracks. Therefore, the amount of deviation between the centers of the set of read heads and write heads is measured on several representative tracks from the inner circumference to the outer circumference of the medium. Then, the shift amount of the track sandwiched between the measurement tracks is obtained by interpolation of the measurement tracks. In this way, the positioning of each head can be realized by measuring / saving the amount of deviation between the centers of the read head and the write head in each dual head.

As a document that discloses a technique for positioning such a dual head at the track center, Japanese Patent Laid-Open No. 360068/1993 can be cited as an example.

[0008]

The prior art described above measures the offset due to the displacement between the heads at the centers of the read head and the write head (hereinafter sometimes simply referred to as "head displacement") only before factory shipment. Not not. for that reason,
In normal use, it is not possible to deal with the case where the magnitude of the displacement between the heads changes with time. Further, in the future, it is expected that the track interval will be 10,000 TPI (about 2.5 μm in track interval), but the center of the head in the circumferential direction is
Since the two heads are physically attached to each other, the center of each head is inevitably deviated. In other words, the track spacing is 2.5 μm, which is about 1 μm, which is 40% of the track spacing. Therefore, if one head is on-track at the track center and the other head is reading or writing data as it is, the on-track accuracy is required to be within 5% pp of the track interval with respect to the track center. It is impossible from the positioning performance. For this reason, normally only before shipment from the factory,
The positional deviation amount between the read head and the write head on the inner and outer circumferences of the recording medium is measured and stored in the apparatus. Then, using this value, the offset positioning amount of the head is determined according to the access position of each track.

However, in the future, if the head misalignment amount exceeds 40% of the track, the head misalignment amount due to thermal expansion of the head should not be taken into consideration.
The positioning accuracy cannot be suppressed within 5% pp of the track interval. Further, in normal use, if the measurement timing of the head-to-head misalignment amount and the measurement processing procedure are not taken into consideration, there is a problem that the measurement takes time and the operation performance of a normal disk device is deteriorated. Further, if too many locations for measuring the head-to-head displacement are provided, there is a problem that the user data storage area is reduced.

A first object of the present invention is to measure the head-to-head displacement even after shipment from the factory, and to position the write head in the separation head in response to the temporal change in the head-to-head displacement. It is to provide a disk device that can be accurately performed.

A second object of the present invention is to provide a disk device in which the measurement of the head-to-head misalignment does not reduce the capacity of the user data storage area.

A third object of the present invention is to provide a head misalignment amount measuring method for measuring the head misalignment amount of a disk device after shipment from the factory.

[0013]

In order to achieve the first object, the first aspect of the present invention is a disk-shaped recording medium,
A drive unit for rotating the medium, a read head for reading, and a separation head each having a write head for writing, and a read / write operation for reading / writing data from / to the medium by the read head and write head. In a disk device having an execution unit, a recording medium has a measurement area for measuring a head-to-head displacement amount which is an amount of displacement of a write head with respect to a read head on a track of the recording medium in a track width direction. The read / write execution unit has a unit for positioning the read head on a specific track in the measurement area, and a read head is positioned on the specific track to detect the deviation amount using the write head. Using a read head and a means for writing a signal for recording on a recording medium,
A means for reading the written signal for detecting the shift amount, and a shift amount based on the read signal, and an offset in the medium radial direction with respect to the track of the write head is adjusted based on the obtained shift amount. And means for doing so.

Further, in order to achieve the above-mentioned second object, the second aspect of the present invention is the same as the above-mentioned first aspect, wherein the measurement areas are provided at different positions on the same surface of the recording medium, and the measurement area is set to 2 per surface. It is characterized in that it is arranged at more than one place, and the read / write execution section is further provided with an interpolating means for obtaining the deviation amount in each track by interpolation based on the deviation amount between heads in each measurement region.

Further, in order to achieve the above third object,
A third aspect of the present invention is a disk-shaped recording medium, a driving unit for rotating the medium, a read head for reading,
And a method of measuring a head-to-head deviation amount, which is an amount of deviation of a write head in a track width direction with respect to a read head on a track of a recording medium, in a disk device including separate heads each having a write head for writing, In each of two adjacent tracks on the recording medium, the read head is positioned at the center of the track width direction, and the write head sends a signal for detecting the deviation amount to different circumferential angles of the two tracks. Is written at the angular position of, the read track is positioned at the center of the boundary between the two adjacent tracks, and the read signal for detecting the written shift amount is read by the read track, and the read signal is read. The feature is that the signals corresponding to the two tracks are extracted and compared to detect the deviation amount. That.

[0016]

According to the present invention, a disc-shaped recording medium, a drive unit for rotating the medium, a read head for reading, and a separation head each having a write head for writing, the read head, and It is applied to a disk device having a read / write execution unit for reading / writing data from / to the medium by a write head. The present invention measures the head-to-head shift amount, which is the shift amount of the write head in the track width direction with respect to the read head on the track of the recording medium, in a normal operation after factory shipment in such a disk device. Means are provided.

Therefore, in the present invention, as the recording medium,
A part having a measurement area for measuring the head-to-head displacement is used in advance. Further, in order to perform the measurement, the read / write execution unit is provided with a means for positioning the read head on a specific track in the measurement area, and a deviation amount is detected by using the write head with the read head positioned on the specific track. Means for writing a signal for recording on the recording medium, a means for reading the signal for detecting the written deviation amount using the read head, and the deviation amount is obtained and obtained based on the read signal. And means for adjusting the offset in the medium radial direction with respect to the track of the write head, based on the amount of deviation.

It is preferable that the measurement areas are arranged at different positions on the same surface of the recording medium at two or more positions on the same surface. If there are multiple media, for each of those faces,
Provide at least two places. In this way, by providing the measurement areas at two or more locations, it is possible to interpolate the head-to-head displacement, as will be described later. This can prevent the capacity of the user's data storage area from decreasing.

Further, it is preferable that the measurement area has a dedicated track. Specifically, two adjacent measurement tracks are prepared for each measurement track. Then, this measurement area can be used for measuring the head-to-head displacement even during normal read / write of the disk device.

Further, the above-mentioned measurement area is 1 per track.
You may have it in several places. By doing so, it is possible to measure the head-to-head deviation amount for each track without lowering the format efficiency. Further, if the format efficiency allows, it may be provided at several places per track or every servo area. By doing so, highly accurate measurement of the head-to-head misalignment amount can be realized.

In order to detect the shift amount, the read / write executing unit first positions the read head in a track width direction on each of two adjacent tracks in the measurement area by means of positioning the read head on a specific track. The signal for detecting the deviation amount is positioned by the center of the
Writing is performed by using a write head at different angular positions on the two tracks. Next, the read head is positioned at a specific track by the means for positioning the read head at a specific track, and the read track is positioned by the means for reading a signal for detecting the deviation amount. The written signal for detecting the deviation amount is read out.

The read / write execution unit can further include an A / D converter for converting the signal read by the read head into a digital signal, since the read / write execution unit performs control processing for positioning the head by a digital signal. The A / D converter can be configured so as to be able to capture the signal a total number of times of capturing the positioning control signal of the head and the number of capturing the signal for detecting the deviation amount at least twice.

The read / write execution unit may further comprise an interpolating means for interpolating the shift amount in each track based on the head-to-head shift amount in each measurement region. This interpolating means can use the head-to-head displacement amount measured in two or more measurement regions per surface of the medium to determine the head-to-head displacement amount in a track other than the track other than the measurement region. For example, linearly interpolating the head misalignment amount for each of a plurality of tracks sandwiched between two measurement regions, based on the number of tracks sandwiched between the head misalignment amounts obtained in the two measurement regions. Can be sought by.

Further, the read / write execution unit may be configured to execute the measurement of the head-to-head misalignment amount in the processing gap for the command from the host device to which the disk device is connected. Thus, by giving priority to the host command processing, it is possible to prevent the operation of the disk device from being affected.

The read / write execution unit can be configured to have a function of measuring the head-to-head shift amount at a measurement interval. That is, the read / write execution unit
It is possible to further include timing control means for executing the measurement of the head-to-head deviation amount in accordance with a predetermined measurement timing, and means for storing the measured head-to-head deviation amount. In this case, the means for adjusting the offset can perform the offset adjustment using the head-to-head shift amount stored in the storing means.

The timing control means may be configured so as to store in advance data that defines the timing for measuring the head-to-head displacement, and determine the measurement timing based on the data that defines this timing. Further, the timing control means determines, as the data for which the timing is determined, the measurement timing at a time interval from the power-on time until reaching a predetermined stable region, the measurement timing having a closer time interval than the measurement timing in the stable region. Can be

The means for storing the head misalignment amount can be constituted by a non-volatile and rewritable memory.

Next, in the measurement of the head-to-head displacement amount in the present invention, the read head is positioned at the center of the track width direction in each of the two adjacent tracks on the recording medium, and the displacement amount is determined by the write head. A signal for detection is written at different angular positions of the two tracks, a read track is positioned at the center of the boundary between the two adjacent tracks, and the read track detects the amount of deviation. Can be carried out by reading out the signal for, the signals corresponding to the two tracks from the read out signal, comparing them, and detecting the deviation amount. In this case, for example, a burst signal can be used as the signal for detecting the deviation amount.
Further, the writing and reading of the signal for detecting the deviation amount can be continuously performed after the positioning of the read head is completed.

In the disk device to which the present invention is applied, which has a head-to-head displacement amount measuring unit for measuring the head-to-head displacement amount, the recording medium can store a plurality of surfaces,
The configuration may include at least a measurement area for measuring the head-to-head deviation amount by the head-to-head deviation amount measuring unit and a user data storage area. In this case, the measurement area is provided on a part of each surface of the recording medium. Then, the storage area of the user data may have a structure in which the storage address numbers are arranged so that the address numbers are allocated to the next surface after the address numbers have been allocated on the same surface. In this way, by allocating the storage address of the user data for each surface, it is possible to reduce the number of times the head-to-head displacement is measured and prevent an increase in the overhead of the disk device.

As described above, according to the present invention, by providing the means for measuring the head-to-head displacement during normal operation,
Even at a high TPI such as 0000 TPI, it becomes possible to deal with the case where the temporal change of the head poses a problem. In addition, when two or more head-to-head deviation amount measurement tracks are provided for each surface of each medium, and when accessing a normal track that does not have a measurement portion, by interpolating from the above measured value according to the track position, the medium It is possible to avoid a decrease in the storage area for user data.

Further, in this measuring operation, the rate of temporal change of the head-to-head displacement amount can be grasped in advance, and the measuring operation can be performed in a cycle that does not affect the normal disk operation as much as possible. The rate of change over time can be stored / changed in a non-volatile medium such as a medium or a flash (FLASH) memory, so that the latest rate of change in the interval between heads can be grasped and the amount of head-to-head deviation can be measured. It can be used for determining the gap, calculating the gap correction value at the position of the head of the head-to-head displacement, and the like.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic disk device to which the present invention is applied will be described below with reference to FIGS. 1, 2, 3, 4, 5, 5, and 7. Of course, it may be realized as a peripheral device such as a floppy disk device, a magneto-optical disk device, an MD device, or a system device in which the peripheral device is attached to the host.

FIG. 1 is a format diagram of a head-to-head deviation amount measuring method according to an embodiment of the present invention. Generally, the data format of the disk device is divided into sectors 101, 102, 103 as the minimum storage unit of user data. Further, there is a servo area 104 in which information for positioning control of the head on the corresponding track is stored.
The other user data storage area is the data area 10
It becomes 5.

Here, consider a case where data is read / written by the separation head 106 including the read head 108 and the write head 107. Servo area 1
An enlarged area of 04 is shown at the bottom of FIG. In this case, as the measurement area, the tracks for measuring the head-to-head shift amount consist of two adjacent tracks. The servo area is
It consists of a track number area 109 and a position signal area 110. The servo area including the track number area 109 and the position signal area 110 is recorded by laser length measurement using a servo track writer. As a result, the accuracy of the position signal that serves as the positioning reference can be ensured. Further, in the track number area 109, when the head passes,
The current track number is recorded in gray code that can be read within ± 1 track. For delicate positioning control within the track, the burst signal POSA in the position signal area,
A conventional two-phase position signal is generated from B, C, and D to perform positioning.

In the case of this embodiment, the burst signal P is set so that the read head 108 of the separation head 106 is located at the track center in the adjacent measurement tracks 1 and 2.
OSE and F are recorded by the write head 107. Next, the read head 108 is positioned at the center of the boundary between the measurement tracks 1 and 2 (position indicated by the thick arrow line A in FIG. 1), and from the position signals POSC, D and POSE, F, the deviation of the position signal is detected. The shift between the read head 108 and the write head 107 can be detected.

As described above, when the drive is used normally, it is possible to detect the deviation of the track centers of the read head and the write head in the circumferential direction, that is, the deviation amount between the heads. When this value is used to determine the head to be used according to the instruction from the host, the write head can also be positioned at the track center by offset positioning of the head using this measured value. Of course, the head-to-head misalignment amount measurement cycle is an overhead of processing when viewed from the host, so processing should be performed with a gap between host commands. For example, it may be performed immediately after the host command is processed.

Further, with respect to the change with time of the head-to-head misalignment, if the change occurs in a short time due to thermal expansion or the like, the change is investigated in advance, and the actual head-to-head misalignment is measured by the positioning control. By measuring at an optimal interval when it affects the
It goes without saying that the overhead seen from the host of the disk device can be reduced.

FIG. 2 is a track diagram for measuring the head-to-head displacement amount in the recording medium used in one embodiment of the present invention. This is the measurement track 20 as a measurement area.
In this example, 2, 203 and 204 are arranged in two or more places on each surface of the medium 201. In this example, medium 2
In the radial direction of 01, the inner peripheral portion, the intermediate portion and the outer peripheral portion are provided at three locations. Then, in a track that stores normal user data without a measurement track, the preceding measurement track is used to interpolate according to the track number position accessed by the head to calculate the head-to-head shift amount at that position. And used as an offset value for positioning control.

Having two or more measurement tracks on each side of the medium 201 is particularly important in the rotary actuator system. The reason for this is that the angle between the inner circumference and the outer circumference of the track formed by the head in the circumferential direction of the track changes, and the magnitude of the head-to-head deviation changes.

As described above, it is possible to realize the measurement of the head-to-head shift amount while suppressing the deterioration of the storage efficiency of user data due to the measurement track of the medium to the minimum.

FIG. 3 shows an example of a layout diagram of logical access numbers of user data. In the case of a disk device, the logical number from the host is converted into a physical cylinder number, head number, and sector number within the disk device. In the normal case, since the track movement of the head takes much longer than the time of switching to another surface of the same track, it is usual to associate a logical number from the host in the same cylinder. However, in the case of the present invention, the measurement of the head misalignment amount is
Since the amount of deviation differs for each head, it must be performed for each head. Therefore, it is not a good idea to assign the logical number of the host in the same cylinder.
Therefore, as shown in FIG.
2, 303, sector 3 for each track 304
05 are assigned consecutive numbers. As a result, when the host logical access numbers are consecutive, the offset of the head-to-head shift amount reduces the need to measure another head-to-head shift amount, and thus can suppress the increase in the overhead of the disk device. .

As described above, the correspondence between the logical number of the host and the physical position of the disk device is continuously arranged for each track in the sector on the same medium, and after the logical-physical correspondence of the same surface is completed, the next surface is displayed. Assign to. By doing so, the number of times of measuring the deviation of the center of the read head and the write head in the track direction in the separation head of the disk device is reduced, and the increase of the overhead of the disk device can be prevented.

FIG. 4 shows a procedure for measuring the head-to-head shift amount of the separation head. First, the read head 108 of the separation head 106 is on-track to the 402 of the measurement track 1 and the burst signal POSE is applied to the write head 107.
To record on the medium. The case where the start of burst writing at this time is the index 401 will be described. When the writing of the measurement track 1 is completed by the head following the movement trajectory of the head, the head is moved to the adjacent track, that is, the measurement track 403. Then, when the on-track of the read head 108 to the measurement track 2 is completed, the write head 107 outputs the POSF which is a burst signal.
Write. Then, the write head 107 finishes writing the measurement track 2 in accordance with the movement trajectory of the head.

Next, the head 106 is moved to the measurement track 1,
Positioning is performed so that the read head 108 is positioned at the intermediate point of 2. Then, the position signal generated from POSE and POSF is read. This signal is applied to the write head 10 with respect to the read head 108 as shown in the relationship of FIG.
It is possible to measure the positional deviation amount of 7.

By the way, at present, the rotation speed of the disk device is about 5400 rpm (= 11.1 ms), and one track movement of the head is about several ms.
Positioning control is completed in about 1/4 rotation. It takes 5 rotations to write / read data after waiting for the head of the track index pulse to be generated, which is inefficient because it takes 5 rotations. Therefore, as shown in FIG. 4, processing is started each time positioning is completed. As a result, the measurement process can be performed with a little over three rotations, and the overhead due to the measurement of the disk device can be reduced.

As described above, it is possible to realize the disk device in which the performance deterioration due to the overhead is suppressed to the minimum.

FIG. 5 is a block diagram of an electronic circuit of a disk device according to an embodiment of the present invention. An outline of the configuration of the electronic circuit of this disk device and its movement will be described in the state of standard data reading. It should be noted that parts having the same functions as those described above are designated by the same reference numerals. Here, consider a case where the disk device 512 and a host computer (abbreviated as a host) 513 are connected via a standard interface.

The disk device 512 is provided with a mechanical section 514 for reading / writing data from / to the medium 201, and a read / write executing section 500 for controlling the operation of the mechanical section 514 to read / write data.

The mechanical section 514 includes the medium 201, the magnetic head 106, and a VCM for driving the magnetic head.
A (Voice Coil Motor) 515 and a spindle motor 516 for rotating the medium are provided.

The read / write execution unit 500 includes an R / W circuit 50.
1, a data processing unit 502, a data buffer 509 connected to the data processing unit 502, a central processing unit (CPU) 505 that controls the operation of the disk device, and a CPU 5
05 and the flash memory 515 and the CPU5
A mechanical control unit 511 connected to 05 and a mechanical control unit 514 controlled by the mechanical control unit to rotationally drive the medium 201 and drive the head 106 to read / write data.

The data processing unit 502 has a CPU interface control unit 504 connected to the CPU 505.
A host interface control unit 510 connected to the host 513, a buffer control unit 507 connected to the data buffer 509, and an R / W circuit 50.
1 and a drive interface control unit 503, and an ECC processing unit 506 connected to the drive interface control unit 503. C
The PU interface control unit 504 is connected to the host interface control unit 510, the buffer control unit 507, and the drive interface control unit 503, and exchanges data. Further, the buffer control unit 507 is connected to the host interface control unit 510 and the drive interface control unit 503 to exchange data.

The mechanical control unit 511 has a function A for performing digital positioning control of the head.
A / D converter 508 and a D / A converter 517 are mounted. This A / D converter 508 is
The position signals POSA, B, C, are connected to the W circuit 501.
A multiplexer (not shown) is added so that D, E and F can be taken in. In addition, a mechanical unit 51 described later
In the case of measuring the control current of the VCM 515 of No. 4 and the like, it is necessary to have terminals that can take in them.

The CPU 505 can realize various functions by operating the data processing unit 502, the mechanical control unit 511, the R / W circuit 501 and the flash memory 515 according to the program stored in the built-in memory. That is, in the measurement area, a unit for positioning the read head 108 on a specific track and a signal for detecting the amount of deviation are recorded on the recording medium by using the write head 108 with the read head 108 positioned on a specific track. 201, means for reading the written signal for detecting the deviation amount using the read head 108, and based on the read signal,
And means for adjusting the offset in the medium radial direction with respect to the track of the write head 107 based on the calculated shift amount. Further, in the present embodiment, the CPU 505 performs the interpolating means for interpolating the displacement amount in each track based on the displacement amount between the heads in each measurement region and the measurement of the displacement amount between the heads according to a predetermined measurement timing. Timing control means for executing,
And means for storing the measured head misalignment amount.

The means for adjusting the offset adjusts the offset by using the head-to-head shift amount stored in the storing means. Further, the timing control means stores in advance data that defines the timing for measuring the head-to-head displacement amount, and determines the measurement timing based on the data that defines this timing. In this case, the timing control means, as will be described later, as the data for which the timing is determined, the measurement timing in the time from when the power is turned on to when it reaches the predetermined stable region is a time denser than the measurement timing in the stable region. The measurement timing of the interval can be defined. Further, the means for storing the head misalignment amount can be configured by using a non-volatile and rewritable memory, for example, a flash memory 515.

Next, the operation of the disk device configured as described above will be further described. First, the host 513
An instruction to read more data is sent to the disk device 512 according to the interface protocol. The command transferred to the disk device 512 is received by the host I / F control unit 510 in the data processing unit 502 of the disk device 512, sent to the CPU 505 via the CPU I / F control unit 504, and the command is sent. Interpretation takes place. Then, the CPU 505 starts the work of reading the data of the corresponding sector of the drive. From this, the read operation of the corresponding sector instructed by the host 513 is started.

Here, the mechanical section 514 comprises the medium 201, the magnetic head 106, and a VC for driving the magnetic head.
M (Voice Coil Motor) 515, a spindle motor 516 for rotating the medium. The mechanical control unit 511 is instructed by the instruction from the CPU 505 so that the data of the relevant sector can be read out by this mechanical unit. The mechanical control unit 511 controls the mechanical unit according to an instruction from the CPU 505, and positions the magnetic head 106 on the corresponding track of the medium 201. As a result, the data of the corresponding sector is read, and the analog signal is read by the R / W circuit 501 as NRZ (N
on Return to Zero) signal. This signal is taken into the drive I / F control unit 503 of the data processing unit 502.

Next, the read data is subjected to an ECC processing unit 506 for checking the read data for errors.
Then, it is sent to the data buffer 509 via the buffer control unit 507. Then, when the relevant sector is read and the ECC processing unit 506 reports that no error has occurred, the read data stored in the data buffer 509 is transferred to the host interface control unit 510.
And is transferred to the host 513 via.

On the other hand, the A / D converter 508 takes in the position signals POSA, B, C, D, E and F. Therefore, in addition to the information previously captured by the control system, it is possible to handle two more pieces of information, so that POSE, F
Can be captured. The information on the head-to-head displacement thus measured is stored in the FLASH memory 515, which is a non-volatile memory, the medium 201, or the like, with the intervention of the CPU 505. Then, by using this stored value at the time of positioning, it is possible to realize the positioning control corresponding to the temporal change of the head-to-head displacement amount.

As described above, it is possible to provide a disk device capable of measuring and adjusting the deviation of the center of the head.

FIG. 6 is a graph showing an example of the time interval for measuring the head-to-head displacement amount, which is applied in one embodiment of the disk device of the present invention. This shows at what timing the head-to-head displacement amount should be measured according to the rate of change in the head-to-head displacement amount after the power of the disk device is turned on. First, as shown in FIG. 6, the amount of head-to-head deviation changes abruptly after the power is turned on.
After that, consider the case where it becomes saturated. In this case, when the inclination is steep, the measurement interval 601 is made dense. On the other hand, once the changes have settled down, it is better to make them sparse. This interval is determined by a time interval that does not affect the head positioning control.

Therefore, a method is conceivable in which the rate of change in the head-to-head displacement is measured and the measurement interval is determined before the product is shipped, and the head-to-head displacement is measured accordingly. In addition, at the measurement timing of the head gap amount that can follow the maximum change in the head gap amount, the measurement is performed first, and the measured data is saved at this time, and the change rate is used for head positioning control. If it does not affect the situation, it may be possible to increase the measurement interval.

As described above, by optimizing the measurement interval, it is possible to realize a disk device which can minimize the increase in the overhead seen from the user of the disk device. The data for setting the measurement interval is stored in, for example, the flash memory 515, the medium 201, or the like.

FIG. 7 is a diagram showing a head-to-head displacement amount measurement region showing an embodiment of the present invention. In this example, the head misalignment amount measurement area 701 is provided only in the servo area of the index portion of each track of the medium 201. As a result, the head-to-head displacement amount can be measured for each track, and the head-to-head displacement amount according to the track position of the head can be measured more accurately. Of course, if the format efficiency is sufficient, the head displacement amount can be measured with higher accuracy if the head displacement amount can be measured for each servo area.

As described above, highly accurate measurement of the head-to-head shift amount can be realized while suppressing the deterioration of the format efficiency.

[0065]

As described above, according to the present invention,
It is possible to normally implement on-track reading and writing even during normal use, even when the head misalignment amount changes with time when the TPI becomes high such as 10000 TPI. Furthermore, by arranging logical sectors on the same medium surface, adjusting the measurement interval, and shortening the measurement time,
It is also possible to minimize the increase in the overhead of the disk device due to the measurement of the head-to-head displacement.

Further, by concentrating the head misalignment amount measurement area at a specific position on the medium, it is possible to realize highly accurate head misalignment amount measurement without significantly sacrificing the user data storage area.

[Brief description of drawings]

FIG. 1 is a format diagram showing a method of measuring a head-to-head displacement amount according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of a head-to-head deviation amount measurement track in an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an arrangement of logical access numbers of user data according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a procedure for measuring a head-to-head displacement amount according to an embodiment of the present invention.

FIG. 5 is a block diagram showing an electronic circuit configuration of a disk device according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing measurement time intervals of the head-to-head displacement amount in the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a measurement region of a head-to-head displacement amount according to an embodiment of the present invention.

[Explanation of symbols]

101 ... Sector, 104 ... Servo area, 105 ... DAT
A area, 106 ... Separation head, 109 ... Track number area, 110 ... Position signal area, 201 ... Medium, 202 ... Measurement track, 301 ... Medium, 304 ... Track, 305
... sector, 401 ... index, 402 ... measurement track 1, 403 ... measurement track 2, 500 ... read / write execution unit, 501 ... R / W circuit, 502 ... data processing unit, 50
5 ... CPU, 508 ... A / D, 511 ... Mechanical control unit, 5
12 ... Disk device, 513 ... Host, 517 ... D /
A, 701 ... Head shift amount measurement area.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Yamamoto 5-20-1 Kamimizumoto-cho, Kodaira-shi, Tokyo Incorporated company, Hitachi, Ltd. Semiconductor Division (72) Inventor Masatoshi Nishina 2880 Kozu, Odawara-shi, Kanagawa Shares Hitachi Storage Systems Division

Claims (17)

[Claims] 1. A disk-shaped recording medium, a drive unit for rotating the medium, a read head for reading, and a separation head each having a write head for writing, and the read head and write head. In the disk device having the read / write execution unit for reading / writing data from / to the medium according to the above, the recording medium is a head gap which is an amount of deviation of the write head in the track width direction with respect to the read head on the track of the recording medium. A read / write execution unit has a means for positioning the read head on a specific track in the measurement area, and a read head is positioned on a specific track. In this state, the write head is used to write a signal for detecting the deviation amount to the recording medium, and a read Means for reading the written signal for detecting the shift amount by using a pad, and the medium for the track of the write head based on the calculated shift amount, based on the read signal And a means for adjusting an offset in the radial direction. 2. The measurement area according to claim 1, wherein the measurement areas are arranged at two or more locations on the same surface of the recording medium at different positions, and the read / write execution unit is based on the head misalignment amount in each measurement area. The disk device further comprises an interpolating unit that obtains the amount of deviation in each track by interpolation. 3. The disk device according to claim 1, wherein the recording medium has a dedicated track as the measurement area. 4. The disk according to claim 1 or 2, wherein the read / write execution unit executes measurement of the head-to-head misalignment amount in a processing gap for a command from a host device to which the disk device is connected. apparatus. 5. The read / write execution unit according to claim 1, 2 or 3, wherein a timing control unit that measures the head gap amount according to a predetermined measurement timing, and a unit that stores the measured head gap amount. The disk device, further comprising: and the means for adjusting the offset, wherein the means for adjusting the offset adjusts the offset using the amount of head-to-head deviation stored in the means for storing. 6. The method according to claim 5, wherein the timing control means stores in advance data defining a timing for measuring the head-to-head displacement amount, and determines the measurement timing based on the data defining the timing. Characteristic disk device. 7. The timing control means according to claim 6, wherein, as the data for which the timing is determined, the measurement timing in the time from when the power is turned on to when it reaches a predetermined stable region is closer than the measurement timing in the stable region. A disk device characterized in that measurement timings of various time intervals are determined. 8. The disk device according to claim 5, wherein the means for storing the head-to-head shift amount is a non-volatile and rewritable memory. 9. The disk device according to claim 1, wherein there are n measurement areas for the head-to-head displacement amount per track. 10. The disk device according to claim 9, wherein n is 1. 11. The disk device according to claim 1, wherein the recording medium has a servo area, and a head misalignment amount measurement area is arranged for each servo area. 12. The A / D converter for converting a signal read by a read head into a digital signal, since the read / write execution unit performs a control process for positioning the head by a digital signal. The A / D converter further includes at least 2 times the number of times the head positioning control signal is taken in and a signal for detecting the deviation amount.
A disk device which is capable of capturing signals the number of times including the number of times of capturing. 13. The read / write execution unit according to claim 1, wherein the read / write execution unit is configured to position the read head on a specific track, and to read the read head on each of two adjacent tracks in the measurement area. Is positioned at the center of the track width direction, and a signal for detecting the deviation amount is written in the recording medium by a means for writing the signal for detecting the deviation amount at different angular positions of the two tracks. Write and position the read head at the center of the boundary between the two adjacent tracks by means for positioning the read head on a specific track, and read out the read signal by means for reading a signal for detecting the deviation amount. A disk device characterized by reading a signal for detecting the written shift amount by a track. 14. A disk-shaped recording medium, a drive unit for rotating the medium, a read head for reading, and a separation head each having a write head for writing, the read head and the write head. Thus, in a disk device having a read / write execution unit for reading / writing data from / to the medium, the head-to-head shift amount, which is the shift amount of the write head in the track width direction with respect to the read head on the track of the recording medium, is measured. The recording medium is capable of storing a plurality of surfaces, and a recording area for measuring the head deviation amount by the head deviation amount measuring section and a user data storage area. The measurement area is provided on a part of each side of the recording medium, and the user data storage area is Placement of paid address number, the disk apparatus characterized by having a structure for distributing the finished waving address number on the same plane to the next plane. 15. A recording medium in a disk device comprising a disc-shaped recording medium, a drive unit for rotating the medium, a read head for reading, and a separation head having a write head for writing, respectively. In the method of measuring the amount of head-to-head displacement, which is the amount of displacement of the write head in the track width direction with respect to the read head on each track, the read head is moved in the track width direction in each of two adjacent tracks on the recording medium. The write head writes a signal for detecting the amount of deviation at angular positions of different circumferential angles of the two tracks, and reads it at the center of the boundary between the two adjacent tracks. Position the track and read the signal for detecting the amount of deviation written by the read track, A head-to-head deviation amount measuring method characterized in that signals corresponding to two tracks are extracted from the read signals and compared to detect the deviation amount. 16. The head-to-head deviation amount measuring method according to claim 15, wherein a burst signal is used as a signal for detecting the deviation amount. 17. The head-to-head displacement amount measuring method according to claim 15 or 16, wherein writing and reading of a signal for detecting the displacement amount are successively performed after completion of positioning of the read head.