JPH09282818A - Magnetic disk drive and head positioning control system applied thereto - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize highly accurate head positioning control required for high recording density particularly in a magnetic disk drive having employed the recording and reproducing isolation type head. SOLUTION: This device comprises a head positioning control system for controlling the head to position into the range of target track depending on the reproduced burst data by reproducing a pair of burst data of the two phases recorded in each track on the disk. The burst data of the first phase A, B and the burst data of the second phase C, D are respectively recorded in every 2/3 track pitch and thereby the positioning range based on the comparison result of the burst data A, B of the first phase and the positioning range based on the comparison result of the burst data C, D of the second phase are alternately arranged with the interval of l/3 track.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive such as a hard disk drive, and more particularly to a head positioning control system for controlling the positioning of a head on a track based on servo data prerecorded on a disk.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk device such as a hard disk device (HDD) uses a disk as a recording medium and uses a large number of tracks formed on the disk as a recording area. Each track is divided into data areas called a plurality of data sectors. This data sector is a unit of data access.

[0003] In particular, a head positioning control system called a sector servo system is employed in a small HDD. This system arranges servo areas in which servo information is recorded at regular intervals on a disk on a disk, and moves a head to a target track (a track including a sector to be accessed) based on the servo information reproduced from the servo area. Perform positioning control.

Here, the servo information is roughly divided into a cylinder code (track address) and burst data. The cylinder code is code information for identifying each track, and is used for seek control (also called speed control) for moving a head to a target track. Burst data is normally composed of two-phase burst signals A and B and burst signals C and D, and position control for positioning the head within the range of the track positioned by seek control (also called track following control). Used for.

Burst data, as shown in FIG.
The burst signals A and B and the burst signals C and D respectively form a pair, and the burst signals A and B are recorded in the data track (N) at positions displaced by 1/2 track.
The burst signals C and D are recorded at positions shifted by one track. The center of the burst signals A and B corresponds to the track center, and the CPU positions the head at the track center where the error amount of the burst signals A and B becomes zero. The burst signals C and D are used in a positioning range of 1/4 track or more from the track center.

Here, the CPU is a microprocessor and is a main constituent element of the head positioning control system for executing the positioning control of the head mounted on the head actuator.

As described above, in the conventional positioning control (which means the position control in the present invention), the burst signals A and B are transmitted when the positioning range is "center of one track ± 1/4 track". The burst signals C and D are used in the positioning range (-1/2 track to -1/4 track and 1/4 track to 1/2 track) outside thereof.

Here, the burst data is recorded on the disk by a dedicated servo information writing device called a servo writer when the HDD is manufactured. Normally, a servo writer sends a recording head every 1/2 track pitch to write a burst signal for 1/2 track pitch. That is, for example, a method is used in which the same servo signal A is not written at one time, but a half track pitch is written and connected. Therefore, as shown in FIG. 12, there is a connecting portion as indicated by "arrow" in the same signal. The connection accuracy may be adversely affected by the connection accuracy of the connection portion and the magnetic flux leakage due to the edge of the recording head. If the connection portion is adversely affected, an accurate burst signal may not be reproduced, and there is a problem that the accuracy of positioning control decreases.

On the other hand, in recent HDDs, an M reproducing head is used as one of means for realizing a high recording density.
A recording / reproducing separation type head using an R (magnetoresistive) head has attracted attention. This recording / reproducing separation type head uses an inductive type thin film head as a recording head, and the recording head and the M
It has a composite head structure formed by combining with an R head.

The recording / reproducing separated type head must be designed to satisfy the following conditions. First, the head width RW of the reproducing head and the head width WW of the recording head are “RW ≦ WW”.
In a relationship. That is, the head width WW of the recording head is almost close to the track width of the data track with respect to the head width RW of the reproducing head. Second, the read head must be able to reliably read the burst signal anywhere on the track. Thirdly, the recording head may overwrite the data on the adjacent track, but the remaining data can obtain an error rate satisfying the device performance even when read.

[0011]

As described above, in order to realize a high recording density, a recording / reproducing separated type head using an MR head as a reproducing head is drawing attention.
In this recording / reproducing separated type head, since the gap between the reproducing head and the recording head is different and the centers of the gaps are not on a straight line, offsets occur at the data read position and the data write position. Therefore, in the data recording / reproducing operation, it is necessary to offset the position of the reproducing head during recording from the position of the reproducing head during reproduction.

However, when the head width of the reproducing head is smaller than the track pitch, it is not possible to obtain either of the two sets of burst data at the off-track position, and it is impossible to position at the correct position. is there. That is, the above-described second design condition is insufficiently satisfied, and high-accuracy head positioning control required for high recording density cannot be realized.

It is an object of the present invention to realize highly accurate head positioning control required for high recording density, especially in a magnetic disk device employing a recording / reproducing separated type head.

[0014]

According to the present invention, two-phase burst data recorded on each track on a disk is reproduced by a reproducing head, and the head is moved within a target track range on the basis of the reproduced burst data. In a magnetic disk drive equipped with a head positioning control system for position control, the first phase burst data A, B and the second phase burst data C, D are recorded at every 2/3 track pitch, The positioning range based on the comparison result of the burst data A and B and the positioning range based on the comparison result of the second phase burst data C and D are alternately arranged at approximately 1/3 track interval.

With such a configuration, the positioning control range by each burst data can be set to 1/3 track pitch. Therefore, the head width of the reproducing head is set to the track pitch, that is, about 1/3 track pitch width. You can Therefore, as a result, the reproducing head can surely reproduce the burst data anywhere on the track, and it is possible to realize the highly accurate head positioning control necessary for increasing the recording density.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows H related to the first embodiment.
FIG. 3 is a block diagram illustrating a main part of the DD. (System Configuration) As shown in FIG. 1, the HDD of this embodiment has a recording / reproducing separation type in which a reproducing head 10 composed of an MR head and a recording head 11 composed of an inductive type thin film head are integrated on the same slider. A method using the head 1 is assumed. The heads 1 are provided on both sides of the disk 2 and are held by the head actuator 4. The head actuator 4 is rotationally driven by a voice coil motor (VCM) 5 to move the head 1 in the radial direction of the disk 2. The VCM 5 is supplied with a drive current from a VCM driver 6 controlled by a microprocessor 12 (hereinafter, the CPU 20 is described as a main element).

One or more disks 2 (here, one disk is provided for convenience) are provided, and are rotated at a high speed by a spindle motor 3. A large number of concentric tracks are arranged on the disk 2, and each track is provided with a servo area in which servo information including burst data is recorded.

The read / write circuit 7 is usually composed of a dedicated integrated circuit, and executes data read / write processing. The read / write circuit 7 outputs the write data output from the disk controller (HDC) 24 to the recording head 11 via the recording head amplifier 14.
The read signal output from the reproducing head 10 is input via the reproducing head amplifier 13, decoded into reproduced data, and output to the HDC 24.

As described above, the HDD is provided with the head positioning control system (servo system). The head positioning control system is a feedback control system for performing positioning control of the head 1 on a target track (a track including a sector to be accessed) on the disk 2.
The head positioning control system roughly includes a servo processing circuit 8, a sample and hold circuit 9, and a microprocessor 12. The servo processing circuit 13 is usually integrated with the read / write circuit 8 in an integrated circuit.
A cylinder code (address information for identifying a track) and burst signals A to D described later are extracted from the reproduced read signal. The servo processing circuit 13 outputs the cylinder code to the CPU 20 and the burst signals A to D to the sample hold circuit 9.

The sample hold circuit 9 detects and holds each level value of the burst signals A to D. The microprocessor 12 holds the held burst signals A to D
Are converted into digital data by the A / D converter 21 and input. The CPU 20 executes a position error calculation by using the input burst signals A to D, and executes the positioning control of the head 1 (means the position control as described above).

The microprocessor 12 has a memory 22 and a D / A converter 23 in addition to the CPU 20 and the A / D converter 21. The CPU 20 executes a position error calculation process required for positioning control according to a program stored in the memory 22 in advance, and converts the calculated control amount required for positioning control into an analog signal by the D / A converter 23, and Supply to driver 6. (Structure and Operation of First Embodiment) In the above-mentioned HDD, the present embodiment is a case where the range of each track (N + 1, N, N-1) of the disk 2 is divided into three as shown in FIG. Assuming that the burst signals A to D forming the two-phase burst data are recorded at every 2/3 track pitch. That is, the positioning range based on the comparison result of the first-phase burst signals A and B and the positioning range based on the comparison result of the second-phase burst signals C and D are alternately arranged at approximately 1/3 track intervals. Configuration.

When the CPU 20 controls the positioning of the head 1 within the range of the track (N), for example, in each of the burst signals A to D reproduced by the reproducing head, in the positioning range on the track (N + 1) side of the adjacent track. The position error calculation process is executed using the burst signals A and B of the first phase. Also, the track (N-1) of the adjacent track
In the positioning range on the side, the position error calculation processing is executed using the burst signals C and D of the second phase. Therefore, CPU2
0 switches the burst signal used as the positioning control signal for each 1/3 track pitch to execute the positioning control process. For example, the servo signals are switched from servo signals A and B to servo signals C and D, and further switched to servo signals A and B. On the other hand, on the contrary, the servo signals C, D
Switch to B and then to servo signals C and D.

In the positioning control range of the same track (N), there are two areas controlled by either the servo signals A and B or the servo signals C and D, but they are different from each other. Servo signal (C, D or A,
One is determined by observing the magnitude relationship of B).

As described above, according to the present embodiment, the positioning control range by each of the burst signals A to D can be set to 1/3 track pitch. Therefore, the head width of the reproducing head (MR head) 10 is set to the track pitch. , That is, "1/3
Track pitch width + α ”. Therefore, as a result, the reproducing head 10 can surely reproduce the burst data anywhere on the track. (Modification of First Embodiment) FIG. 3 is a view showing a modification of the first embodiment, which has a configuration in which so-called connecting portions are eliminated in the same servo signals A to D. That is, at the time of manufacturing an HDD, when recording on a disk by a dedicated servo information writing device called a servo writer, a condition is set so that the gap width (head width) of the recording head is 2/3 or more of the track pitch. Thus, as shown in FIG. 3, each servo signal A to D is recorded by one write operation.

Therefore, since the connecting portion can be eliminated within the same servo signal A to D, the connecting accuracy of the connecting portion and
It is possible to prevent a situation in which the connection portion is adversely affected by the influence of the magnetic flux leakage due to the edge of the recording head. As a result, since the burst signal having low reliability at the connecting portion is not reproduced, the accurate burst signal can always be reproduced and highly accurate positioning control can be realized. (Second Embodiment) In the second embodiment, in the burst data structure as described above, each data track (N +
1, N, N-1), the cylinder code (SC) setting method. The cylinder code is address information for identifying each track, as described above,
Normally, as shown in FIG. 5, absolute cylinder codes (SC = N + 1, N, N-) corresponding to each track on a one-to-one basis.
1) is set. With this setting method, the track number (address) on the device and the actual track number (address) correspond one-to-one.

In contrast to such a method, the present embodiment
As shown in FIG. 4, the burst signals A to D are assumed to be one combination, and one absolute cylinder code is assigned to each combination. That is, the absolute cylinder of the device is 1.5 cylinder code. Specifically, as shown in FIG. 4, two tracks (N, N-1) on the device correspond to three absolute cylinder codes (K, K-1, K-2). .

In this embodiment, the CPU 20 records the relationship between the cylinder code and the track in the memory 22 as a table. In the case of adopting such a cylinder code allocation method, for example, when positioning at a position across the cylinder codes K and K-1, the CPU 20 determines the position of the track by comparing the magnitude of the burst signals C or D. Confirm. (Third Embodiment) The third embodiment is a burst calculation process (position error calculation process) when an absolute cylinder code corresponding to each track is set in the burst data structure as described above. Method. Hereinafter, description will be made with reference to FIGS.

First, it is assumed that the disc 2 has a track format as shown in FIG. As described above, the burst signals A to D forming the burst data are recorded at the 2/3 track pitch. Further, absolute cylinder codes (N-4 to N + 4) corresponding to one-to-one are set to each track (N-4 to N + 4).

In such a configuration, when the head 1 is positioned and controlled within the range of each track, if the on-track position within the range of each track is "0" to "2", the cylinder code and servo A burst operation pattern using signals is as shown in FIG. Here, FIG.
As indicated by a frame 50, the burst operation pattern is a repetition of 4 patterns.

The positioning control processing in this embodiment will be described in detail below with reference to the flow charts of FIGS. As shown in FIG. 8, the CPU 20 inputs the cylinder code reproduced by the reproducing head 10 and the burst signals A to D while causing the head 1 to seek,
Confirm the target head positioning position (step S1.
S3). The CPU 20 determines which of the three divided positioning ranges (0 to 2 shown in FIG. 6) in the target track range (step S4).

Here, it is assumed that the target rack to be positioned is a cylinder code (N) as shown in FIG. First, in the case of the positioning range (0), the CPU
20 confirms bit 0 of the cylinder code (N) (step S10). If bit 0 is “0”, it is determined that the cylinder is an even number cylinder, and the CPU 20 displays “(B−A)
/ (B + A) ”burst operation is executed (step S
15). On the other hand, if the bit 0 is "1", it is determined that the cylinder is an odd number, and the CPU 20 "(D-C) / (D + C)".
The burst calculation is executed (step S11).

Further, the CPU 20 confirms the bit 1 of the cylinder code, and if the bit 1 is "1", the sign of the burst operation result is inverted for both even and odd cylinders (step S12, S13 and S1
6, S17). The CPU 20 adds the offset amount to the burst calculation result and offsets it from the head positioning position to the target position (step S14).

Next, in the case of the positioning range (1), the CPU 20 determines the bit (b) of the cylinder code (N).
It) is confirmed as 0 (step S20). If bit 0 is "0", it is determined to be an even cylinder, and the CPU 20 executes the burst operation of "(D-C) / (D + C)" (step S25). On the other hand, if bit 0 is "1", it is determined that the cylinder is an odd cylinder, and the CPU 20 determines "(AB)".
/ (A + B) ”burst operation is executed (step S
21).

CPU 20 uses bit 1 of the cylinder code.
If bit 1 is "1", the sign of the burst operation result is inverted for both even and odd cylinders (steps S22, S23 and S26, S2).
7). The CPU 20 adds the offset amount to the burst calculation result to offset from the head positioning position to the target position (step S24).

Further, in the case of the positioning range (2), the CPU 20 makes the bit (b) of the cylinder code (N).
It) is confirmed as 0 (step S30). If the bit 0 is "0", it is determined that the cylinder is an even cylinder, and the CPU 20 executes the burst operation of "(AB) / (A + B)" (step S35). On the other hand, if bit 0 is "1", it is determined that the cylinder is an odd number, and the CPU 20 determines "(C-D)".
/ (C + D) ”burst operation is executed (step S
31).

CPU 20 uses bit 1 of the cylinder code.
If bit 1 is "1", the sign of the burst operation result is inverted for both even and odd cylinders (steps S32, S33 and S36, S3).
7). The CPU 20 adds the offset amount to the burst calculation result to offset from the head positioning position to the target position (step S34).

As described above, when controlling the positioning of the head 1 within the range of the target track (N), the burst which is confirmed in advance in accordance with any one of the three divided positioning ranges (0 to 2). By selecting the corresponding burst operation pattern from the operation patterns (see FIG. 7),
Positioning control of the head 1 can be performed easily and accurately.

[0038]

As described above in detail, according to the present invention, in the magnetic disk drive employing the recording / reproducing separated type head, the positioning control range of each track is set to ⅓ track pitch, whereby the reproducing head Even if the head width is set to the track pitch, that is, about 1/3 track pitch width, the bus and data required for the positioning control can be reliably reproduced. In other words, the reproducing head can surely reproduce the burst data at any place on the track, and as a result, it is possible to realize the highly accurate head positioning control necessary for increasing the recording density.

[Brief description of drawings]

FIG. 1 is an exemplary block diagram showing a main part of an HDD according to a first embodiment of the present invention;

FIG. 2 is a conceptual diagram showing a structure of burst data related to the first embodiment.

FIG. 3 is a conceptual diagram showing a structure of burst data related to a modification of the first embodiment.

FIG. 4 is a conceptual diagram showing a structure of burst data related to the second embodiment.

FIG. 5 is a conceptual diagram showing a structure of burst data related to the second embodiment.

FIG. 6 is a conceptual diagram showing a track format related to the third embodiment.

FIG. 7 is a diagram for explaining a burst operation pattern related to the third embodiment.

FIG. 8 is a flowchart for explaining the operation of the third embodiment.

FIG. 9 is a flowchart for explaining the operation of the third embodiment.

FIG. 10 is a flowchart for explaining the operation of the third embodiment.

FIG. 11 is a flowchart for explaining the operation of the third embodiment.

FIG. 12 is a conceptual diagram showing a structure of conventional burst data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Head (separated recording / reproducing type) 2 ... Disk 3 ... Spindle motor 4 ... Head actuator 5 ... Voice coil motor (VCM) 6 ... VCM driver 7 ... Read / write circuit 8 ... Servo processing circuit 9 ... Sample hold circuit 10 ... Reproduction head (MR head) 11 Recording head 12 Microprocessor 13 Reproduction head amplifier 14 Recording head amplifier 20 CPU 21 A / D converter 22 Memory 23 D / A converter 24 Disk controller (HDC) )

Claims (6)

[Claims] 1. A track formed on a disk is used as a unit of a recording area, and a head is positioned and controlled within the range of the track based on burst data recorded in advance on the track, and the head is positioned with respect to the track. A magnetic disk device for recording or reproducing data according to the above, wherein said burst data comprises at least first phase burst data A, B and second phase burst data C, D, and said first phase burst data A , B, and the positioning range based on the comparison result of the second-phase burst data C, D alternates approximately 1/3.
A magnetic disk device characterized by being arranged at track intervals. 2. A head positioning control system for a magnetic disk device, wherein a track formed on a disk is used as a unit of a recording area, and a head is positioned within the range of the track based on burst data recorded in advance on the track. The burst data is composed of at least first-phase burst data A and B and second-phase burst data C and D, and each burst data A to D is arranged at an interval of about 2/3 track. Yes, when the range of the track is divided into 1/3, the comparison result of the burst data A and B of the first phase and the second burst data
1/3 based on the comparison result of phase burst data C and D
A head positioning control system comprising a control means for positioning control of the head within a positioning range of track intervals. 3. The head is a recording / reproducing separated type head composed of a reproducing head and a recording head, and the gap width of the recording head is 2/3 or more of the track width which is the range of the track, and each burst. 2. The magnetic disk apparatus according to claim 1, wherein the data A to D are continuously recorded on each track of the disk by the recording head at almost ⅔ track intervals without connecting portions. 4. The magnetic disk drive according to claim 1, wherein an absolute cylinder code for identifying each track is recorded on each track. 5. The magnetic system according to claim 1, wherein a combination of the burst data A to D is set in block units, and an absolute cylinder code for identifying each track is assigned to each block. Disk device. 6. An even or odd absolute cylinder code is set for each track, and the absolute cylinder code is associated with each positioning range when the range of each track is divided into 1/3. A preset burst calculation pattern indicating a burst calculation process required for positioning control using the first-phase burst data A and B and the second-phase burst data C and D. After the head is moved to the target track based on the code, a burst calculation process corresponding to each of the positioning ranges in which the head should be positioned within the range of the target track is executed, and the positioning control of the head is executed. The head positioning control system according to claim 2, wherein: