JP2002197818A - Control device, control method for head position of magnetic disk device, magnetic disk adopting this control method and recording medium for recording this control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a head position controller for a magnetic disk device that accurately moves a head to an object position of an object track at a high-speed in recording/reproducing data to/from a magnetic recording medium so as to track the head to the object track. SOLUTION: A servo sector is detected by a change in a period of a detection signal of the servo sector written on a magnetic disk. It is determined that the servo sector is detected when an optional signal period is detected consecutively twice.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a head positioning control of a magnetic disk drive for recording and reproducing information collectively in sector units.

[0002]

2. Description of the Related Art In a conventional magnetic disk device used as an external storage device, there is a method of using servo information recorded in advance on a recording medium for positioning a head. One of them is the sector servo method.
In this method, a positioning servo sector is set at the head of each sector, and position information is written in advance there.
When positioning to the target track, the target track is accessed by recognizing the position information from the servo sector read by the magnetic head. The servo sector is a synchronization and detection unit having data for detecting the servo sector itself,
It is composed of a track number section in which position information of a track is written, and a burst section in which information of a fine position in one track is written.

[0003]

Servo sectors are arranged alternately with data sectors in each sector of a track on a magnetic recording medium. When detecting a servo sector, the servo sector must be separated from the data sector and detected accurately. For this reason, a detection method for reducing erroneous detection due to noise and erroneous detection due to the influence of a defect in a magnetic recording medium is required. In order to perform high-speed recording and reproduction in a magnetic disk device, it is necessary to move a magnetic head to a target track at high speed for positioning. However, if the head is moved at too high a speed, the data of the track number written in the track number portion of the servo sector cannot be accurately read, and the position information of the target track cannot be obtained. Therefore, there is a need for a head position control device that can correctly detect a target track even when the head moves at high speed.

The present invention provides a head position control device for a magnetic disk drive capable of moving a head to a target position on a target track at high speed and accurately when recording and reproducing data on a magnetic recording medium and following the target track. The purpose is to provide.

[0005]

According to the present invention, there is provided a magnetic disk drive head position control apparatus comprising: a magnetic head for recording / reproducing data on a circular track of a magnetic disk; A synchronization detecting unit formed by previously recording a plurality of servo marks having different lengths between data areas for recording data by the magnetic head, which are formed by division, a track number in which a track number is recorded in advance. Section, and a magnetic disk provided with a servo sector having a plurality of burst sections in which burst signals are recorded, when the magnetic head traces the servo mark, the detection output of the magnetic head due to the difference in the length of each servo mark Servo sector detection that determines that the magnetic head has detected a servo sector based on the difference in time length Path and a head position for driving the magnetic head so as to access a target track based on the detected track number, based on a detection result of the servo sector detection circuit. A control circuit is provided.

According to the present invention, the position of the magnetic head on the servo sector is detected based on the difference in the length of the detection signal of the magnetic head for detecting a plurality of servo marks having different lengths. Thereby, the magnetic head can correctly detect the data of the track number portion of the servo sector and know the track number of the track being traced.

A head position control device for a magnetic disk drive according to another aspect of the present invention is a magnetic head for recording and reproducing data on a circular track of a magnetic disk, and divides each circular track into a plurality of pieces along its circumference. A synchronization detecting section in which a plurality of servo marks having different lengths are recorded in advance between data areas for recording data by the magnetic head, a first section having a different length for each track.
And a second pattern connected to the first pattern portion and having a length set such that the sum of the lengths of the first pattern portion and the first pattern portion has a constant value. A magnetic disk provided with a second pattern portion having a portion, a track number portion having a track code portion indicating a track number, and a servo sector having a plurality of burst portions recording a burst signal, and a magnetic head traced the servo mark When it is determined that the magnetic head has detected the servo sector based on the difference in the time length of the detection output of the magnetic head due to the difference in the length of each servo mark, the servo sector of the track traced by the magnetic head is determined. A sector detection circuit for detecting a track number based on the lengths of the first pattern and the second pattern of the track number portion of A head position control circuit for driving the magnetic head to access the target track based on the detected track number. The first pattern and the second
Since the track number is detected on the basis of the difference between the pattern and the length, the track number can be detected even when the moving speed of the magnetic head is high and the track code of the track code portion cannot be read.

A head position control method for a magnetic disk drive according to the present invention is characterized in that a circular track of a magnetic disk is divided into a plurality of tracks along the circumference thereof and is formed between data areas for recording data by a magnetic head. Providing a magnetic disk with a servo sector having a synchronization detector formed by recording a plurality of servo marks having different lengths from each other in advance, a track number recorded in advance by a track number, and a plurality of bursts recorded by a burst signal. When the magnetic head traces the servo mark, a servo sector detection circuit detects that the magnetic head has detected a servo sector based on a difference in detection output time length of the magnetic head due to a difference in length of each servo mark. And based on the detection result of the servo sector detection circuit. The magnetic head detects the number of the track being traced, comprising the step of driving the magnetic head to access the target track based on the detected track number.

According to another aspect of the present invention, there is provided a head position control method for a magnetic disk drive, wherein a circular track of a magnetic disk is divided into a plurality of tracks along a circumference of the track, and the data is recorded by a magnetic head. A synchronization detection unit formed by recording a plurality of servo marks having different lengths in advance between the regions, a first pattern unit having a first pattern having a different length for each track, and the first pattern A second pattern portion having a second pattern whose length is set so that the sum of the lengths of the first pattern portion and the first pattern portion has a constant value, and a track code portion indicating a track number. Providing a magnetic disk with a servo sector having a track number portion and a plurality of burst portions recording burst signals, wherein a magnetic head traces the servo mark When it is determined that the magnetic head has detected the servo sector based on the difference in the detection output time length of the magnetic head due to the difference in the length of each servo mark, the magnetic head detects the servo sector of the track being traced. Detecting a track number by a sector detection circuit based on the lengths of the first pattern and the second pattern of the track number portion of the magnetic head so as to access a target track based on the detected track number. Is driven.

The magnetic disk of the present invention has a plurality of servos having different lengths between data areas for recording data with a magnetic head, which are formed by dividing a circular track into a plurality of sections along the circumference thereof. A servo sector having a synchronization detection section formed by recording a mark in advance, a track number section recording a track number in advance, and a plurality of burst sections recording a burst signal is provided.

A magnetic disk according to another aspect of the present invention is formed by dividing a circular track into a plurality of tracks along the circumference thereof.
Synchronous detection section in which a plurality of servo marks having different lengths are recorded in advance between data areas for recording data by a magnetic head, first pattern section having first patterns having different lengths for each track A second pattern portion having a second pattern connected to the first pattern portion and having a length set so that the sum of the lengths of the first pattern portion and the first pattern portion has a constant value; There are provided a track number section having a track code section indicating a number, and a servo sector having a plurality of burst sections in which burst signals are recorded.

The medium on which the head position control method of the present invention is recorded is formed by dividing a circular track of a magnetic disk into a plurality of tracks along the circumference thereof, between data areas for recording data by a magnetic head. A magnetic disk provided with a servo detector having a synchronization detection unit formed by recording a plurality of servo marks having different lengths in advance, a track number unit prerecorded with a track number, and a plurality of burst units recording a burst signal. Providing, when the magnetic head traces the servo mark, the servo sector detects that the magnetic head has detected a servo sector based on the difference in the time length of the detection output of the magnetic head due to the difference in the length of each servo mark. Determining by a detection circuit, and based on a detection result of the servo sector detection circuit. , The magnetic head detects the number of the track being traced, are recorded the step of driving the magnetic head to access the target track.

A recording medium on which a head position control method according to another aspect of the present invention is recorded is formed by dividing a circular track of a magnetic disk into a plurality of tracks along a circumference thereof, for recording data with a magnetic head. A synchronization detecting section formed by recording a plurality of servo marks having different lengths in advance between data areas; a first pattern section having a first pattern having a different length for each track; A second pattern portion having a second pattern connected to the pattern portion and having a length set so that the sum of the lengths of the first pattern portion and the first pattern portion has a constant value; a track code portion indicating a track number Providing on a magnetic disk a servo sector having a track number portion having a plurality of burst portions and a plurality of burst portions recording burst signals. When the magnetic head traces the servo mark, it is determined that the magnetic head has detected a servo sector based on the difference in the time length of the detection output of the magnetic head due to the difference in the length of each servo mark. A step of detecting a track number by a sector detection circuit based on the lengths of the first pattern and the second pattern of the track number portion of the servo sector of the track being traced by the head; and based on the detected track number. The step of driving the magnetic head to access the target track is recorded.

[0014]

FIG. 1 shows a preferred embodiment of the present invention.
This will be described with reference to FIG.

Embodiment FIG. 1 is a block diagram of a head position control device of a magnetic disk drive according to an embodiment of the present invention. 2A is a plan view of a magnetic disk 1 as an example of a magnetic recording medium, FIG. 2B is a plan view showing one track 1A of the magnetic disk 1 in a band shape, and FIG. It is an enlarged view. 1 and 2, the magnetic disk 1 is rotated by a spindle motor 15.
On the track 1A of the magnetic disk 1, servo sectors 50 in which positioning data is recorded in advance and data areas for recording and reproducing data by a user, that is, data sectors 51, are alternately provided along a circular track. The magnetic head 2 is a head that reads and writes data on the magnetic disk 1. The VCM 14 is a driving device for moving the magnetic head 2 to a target track. The head amplifier 3 receives and amplifies the reproduction signal from the magnetic head 2 and outputs the amplified signal to the AGC amplifier 4. The AGC amplifier 4 keeps the amplified reproduction signal at a constant level and converts it into a binarizing circuit 5.
Is applied. The binarization circuit 5 converts the reproduction signal obtained from the AGC amplifier 4 into a digital reproduction signal, and applies the digital reproduction signal to the servo sector detector 6. The servo sector detector 6 has a timer 6A, detects the servo sector 50 based on a digital reproduction signal, and applies the detection signal to the detection timing generator 7. The detection timing generation unit 7 includes the servo sector 50
, A detection timing for detecting the track number section 17 and the burst sections 19 to 22 is generated and applied to the track generation section 8.

The track data generating section 8 detects the data of the track number section 17 and the data of the servo sector number section 18 which will be described later in detail from the digital reproduction signal, and detects the position of the magnetic head 2 on the track 1A. The position signal generating section 9 is a burst section for positioning the magnetic head 2 so as to trace the center of the track 1A.
Is converted into an analog voltage value and output as a position signal. The A / D conversion circuit 10 converts the analog position signal into
The signal is converted into a digital position signal for digital processing and applied to the position / speed recognition unit 11. The position / speed recognition unit 11
The current position and moving speed of the head are detected from the digital position signal and the data in the track number section 17, and these data are applied to the control amount calculation section 12 of the head position control device 101. The control amount calculation unit 12 moves the magnetic head 1 to a target track, calculates a control amount for following the track, and applies the control amount to the driver 13. Driver 13
Is a voice coil motor (VCM) 14 based on the control amount.
And the spindle motor 15. Position / speed recognition unit 1
1 and the control amount calculation unit 12 are realized by software using respective CPUs.

Next, the operation of the head position control apparatus of the present embodiment will be described with reference to FIGS. 1, 2, 3 and 4. The magnetic disk 1 has a large number of concentric tracks 1A, and the outermost track is set to a track number 0, and numbers are sequentially increased toward the inner circumference. As shown in FIG. 2B, in each track 1A, servo sectors 50 and data sectors 51 are alternately arranged along the circumference. Each servo sector 50 includes a synchronization detection section 16, a track number section 17,
Servo sector number part 18, burst parts 19, 20, 2
1, 22.

FIG. 3 is a diagram showing a data arrangement of the synchronization detecting section 16 of the servo sector 50 shown in FIG. 2C. The detection of the servo sector 50 is performed by detecting the data arrangement pattern of the synchronization detection unit 16. In the synchronization detector 16, n + 1 (n is a predetermined integer) servo marks (indicated as SM in FIG. 3) 23A to 23F are recorded in advance. The servo marks 23 </ b> A to 23 </ b> F are detected by the magnetic head 2 relatively moving in the direction of the arrow X due to the rotation of the magnetic disk 1. The length of the detection time of each of the servo marks 23A to 23F in the detection output of the magnetic head 2 is hereinafter referred to as "period". The cycle of the last servo mark (SM ₀ ) 23A is M times (M × T) the reference cycle T of a known servo pattern (not shown) constituting the servo mark (M is a predetermined integer). . The cycle of the _first servo mark (SM ₁ ) 23B is M + 1L × T
(L is a predetermined integer), and the cycle of the head servo mark (SM _n ) 23F is M + nL × T. That is, the cycle of the head F is the longest, and the cycle of the servo mark (SM ₀ ) 23A is the shortest. The servo sector detector 6 determines which servo mark in the servo marks 23A to 23F has been detected from the difference in the cycle of each servo mark.

The operation of the servo sector detector 6 will be described with reference to FIGS. Track 1 with magnetic head 2
When moved to A, the beginning of the servo mark (SM n) _23F at step 50 in FIG. 4 for the "detection judgment" determines whether it has been detected. If detected, step 5
Proceeding to ₁ , the detection of the next servo mark (SM _n-1 ) 23E is determined. In step 50, the servo mark (SM _n )
When 23F is not detected, the process proceeds to step 59,
The detection of the servo mark (S _n-1 ) 23E is determined. If the servo mark (SM _n-1 ) 23E is detected in step 59, the process proceeds to step 60, where the servo mark (SM _n-1 ) is detected.
_n-2 ) Perform 23D detection determination. By performing such detection determination sequentially, for example, as shown in steps 50 and 51, when two consecutive servo marks (SM _n ) 23F and servo marks (SM _n-1 ) 23E are detected,
In step 52, the time is set in the timer 6A of the servo sector detection unit 6.

The time set in the timer 6A in step 52 is the time TD from the start point of the servo mark (SM _n-2 ) 23D to the end point of the servo mark (SM ₀ ) 23A. Similarly time set in the timer 6A at step 61 is the time TC from the start point of the servo marks _(SM n- 3) 23C to the end of the servo mark _(SM 0) 23A. Timer 6A is a subtraction timer, and the set time is
Decreases over time. When it is determined that the time set in step 62 has become zero, the timer 6A outputs a timing generation signal to the detection timing generation unit 7. The timing of the output of the timing generation signal is determined by the magnetic head 2
, The detection of the synchronization detection unit 16 of the servo sector 50 ends, and the detection substantially coincides with the start of detection of the track number unit 17. The detection timing generator 7 having received the timing generation signal generates a detection timing signal for detecting the track number section 17, the servo sector number section 18, and the burst sections 19 to 22, and applies the detection timing signal to the track data generation section 8.

When the processing of the flowchart of FIG. 4 is continued from step 50 to step 55, the servo mark (SM _n ) 23F to the servo mark (SM ₀ ) 23
This indicates that all the servo marks up to A have been detected. This state is set to "detect all servo marks" in step 56. Only in this state, data is recorded in the data sector 51 of FIG. 2B in a later step. When the processing from step 59 to step 62 is performed, a part of all the servo marks
The servo mark (SM _n-1 ) 23E and the servo mark (S
(M _n−2 ) 23D is detected, so that in step 63, “part of servo mark is detected” is set. Steps 58, 68 and 71 also show the same state as step 63. If two consecutive servo marks are not detected, in step 72, "servo mark cannot be detected" is set. In the states of steps 63 and 72, data is not recorded in the data sector 51.

The track data generator 8 receiving the detection timing signal detects a track number section 17 and a servo sector number section 18 from the data detected by the magnetic head 2. Hereinafter, the track number part 1 will be described with reference to FIGS.
7 will be described in detail. FIG. 5A is a plan view of the track 1A showing the data arrangement of the track number portion 17 of the servo sector 50, and a part of (N + 1) (N is an integer) concentric tracks 1A of the magnetic disk 1 is formed in a belt shape. It is represented by the figure. The track number section 17 includes a pattern A section 26, a pattern B section 27, and a track code section 28. A track code indicating a track number is recorded in the track code section 28. If this is detected, the track number can be detected. However, if the moving speed of the magnetic head 2 is too fast, the track code may not be detected accurately. In this embodiment, when the moving speed of the magnetic head is equal to or higher than a predetermined value, the pattern A portion 26 and the pattern B
The unit 27 can detect the track number. (A) of FIG.
, (N + 1) tracks are numbered from 0 to N, and are displayed as tracks 0 to N. In the (N + 1) tracks, track codes specifying the respective tracks are previously recorded in the track code portions 28 of the tracks 0 to N. In track 0 to track N, different pattern data are recorded in advance in the pattern A section 26 and the pattern B section 27. When the respective pattern data of the pattern A section 26 and the pattern B section 27 are detected by the magnetic head 2, the detection signal of the pattern data of the pattern A section 26 and the detection signal of the pattern data of the pattern B section 27 are completely different from each other, Each pattern data is determined so that it can be easily distinguished.

In each of tracks 0 to N, pattern A
The sum of the length Ka of the portion 26 and the length Kb of the pattern B portion 27 is a constant length K. Pattern A on outermost track 0
The length Ka of the portion 26 is the shortest, and the length Kb of the pattern B portion 27 is the longest. In the innermost track N, pattern A
The length Ka of the 26 portion is the longest, and the length Kb of the pattern B portion 27 is the shortest. From the track 0 to the track N, the length Ka of the pattern A section 26 increases sequentially, and accordingly, the length Kb of the pattern B section 27 decreases sequentially.

FIG. 5B is a waveform diagram of the output signal S of the magnetic head 2 tracing the track number portion 17 of the track 0. The output signal S includes a positive first signal 500 output at the start point of the pattern A unit 26, a positive second signal 501 output at the end point of the pattern B unit 27, and the pattern A unit 2
6 and a negative third signal 502 output at the boundary between the pattern B section 27 and the pattern B section 27.

FIG. 6 is a block diagram showing a detailed configuration of the track data generator 8 of FIG. 1, and FIG. 7 is a flowchart showing the operation. The data of the track number section 17 output from the binarization circuit 5 is applied to the cycle detection section 29 and the track number detection register 30. The cycle detector 29 determines the time between the first signal 500 and the third signal 502 (hereinafter, A
The period A) and the time between the third signal 502 and the second signal 501 (hereinafter referred to as the B period) are measured (steps 80 and 81 in FIG. 7), and the data of the A period is stored in the A period fetch register 31. The B cycle data is applied to the B cycle fetch register 32. A period capture register 3
1 temporarily holds the data of the A cycle, and the B cycle fetch register 32 temporarily holds the data of the B cycle. The held data of the period A and the data of the period B are simultaneously inputted to the track recognition unit 34 based on the period. The track recognizing unit 34 based on the cycle calculates the following equation to obtain the time KT (step 82).

KT = {A cycle / (A cycle + B cycle)}
(N + 1) -OS

Here, "OS" is a constant set so that the time KT in the track of track number 0 becomes zero. A table indicating the correspondence between the time KT and the track number is provided in advance in a memory (not shown) in the track recognition unit 34 based on the cycle, and the track number is determined with reference to this table.

The track number detection register 30 temporarily holds the data of the track code section 28 of the input data of the track number section 17. Track code section 28
Are input to the track code recognizing unit 33 in synchronization with the data of the period A and the data of the period B. In the track code recognition section 33, the track code section 2
The track number is determined based on the track code of No. 8 (not shown). Each track number determined by the track code recognition unit 33 and the track recognition unit 34 based on the period is input to the position / speed recognition unit 11.

As shown in the flowchart of FIG. 8, the position / speed recognizing section 11 moves the magnetic head 2 at the time of the access operation and the distance 2TW which is twice the width of the track 1A.
Is compared with the value obtained by dividing by the cycle SP of the servo sector 50 (step 90). If the moving speed Hv is greater than or equal to the result, the process proceeds to step 91, and the moving speed of the magnetic head 2 is obtained based on the change in the track number obtained by the periodical determination of the track recognizing unit 34 (step 92). . Thus, the track number can be detected even when the moving speed of the magnetic head is high. If the moving speed Hv is smaller than the result value, step 9
Proceeding to 3, the moving speed of the magnetic head is obtained based on the change in the track number obtained by the track code recognizing unit 33 (step 92). The position / speed recognizing unit 11 uses the burst signals 19 to 22 input from the position signal generating unit 9 via the A / D converting unit 10 to generate a control signal for controlling the magnetic head 2 to trace the center of the track 1A. It is added to the control amount calculation unit 12. The control amount calculation unit 12 calculates a control amount of the magnetic head 2 in the radial direction of the magnetic disk 1 based on the control signal, and applies the control amount to the driver 13.

Recording of data in the data sector 51 shown in FIG. 2B by the magnetic head 2 is performed only in the state of "detection of all servo marks" shown in step 56 of FIG. As shown in step 63, the recording operation is not performed in the state of "partially detected servo mark".

As described in detail in the above embodiments, the present invention detects the position of the target track accurately to control the magnetic head, and moves the magnetic head to the target track at high speed and high accuracy. To follow the track. Even if noise is superimposed on the servo signal or disturbance occurs in the actuator that moves the magnetic head, the operation of the data head can be controlled stably.

[Brief description of the drawings]

FIG. 1 is a block diagram of a head positioning device according to an embodiment of the present invention.

2A is a plan view of a recording medium, FIG. 2B is a plan view showing tracks of the recording medium in a band shape, and FIG. 2C is an enlarged view of a servo sector.

FIG. 3 is a diagram illustrating a synchronization detection unit of a servo sector according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a process of detecting synchronization of a servo sector in the embodiment of the present invention.

FIG. 5A is a plan view of each track showing a track number portion of a servo sector according to an embodiment of the present invention. FIG. 5B is a plan view of a track showing the relationship between the A period and the B period of the track number portion.

FIG. 6 is a block diagram of a track data generation unit according to the embodiment of the present invention.

FIG. 7 is a flowchart of track number determination in the embodiment of the present invention.

FIG. 8 is a flowchart illustrating a process of obtaining a speed according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk 2 Magnetic head 3 Head amplifier 4 AGC amplifier 5 Binarization circuit 6 Servo sector detection part 7 Detection timing generation part 8 Track data generation part 9 Position signal generation part 10 A / D conversion circuit 11 Position / speed recognition part 12 Control amount Calculation section 13 Driver 14 Voice coil motor 15 Spindle motor 16 Synchronization detection section 17 Track number section 18 Servo sector number section 19 Burst section 20 Burst section 21 Burst section 22 Burst section 23 A-23F servo mark 26 Pattern A section 27 Pattern B section 28 Track code section 29 Period detection section 30 Track number detection register 31 A period capture register 32 B cycle capture register 33 Track code recognition section 34 Track recognition section based on cycle 50 Servo sector

Claims (24)

[Claims] 1. A magnetic head for recording and reproducing data on and from each circular track of a magnetic disk, wherein each of the circular tracks is divided into a plurality of pieces along the circumference thereof, and the magnetic head is used to record data with the magnetic head. Servo sectors are provided between data areas, and in each servo sector, a synchronization detecting section formed by recording a plurality of servo marks having different lengths in advance, a track number section having a track number recorded in advance, and a burst signal are recorded. A magnetic disk provided with a plurality of burst portions, wherein when the magnetic head traces the servo mark, based on a difference in time length of the detection output of the magnetic head due to a difference in length of each of the plurality of servo marks. Servo sector detection circuit for determining that a magnetic head has detected a servo sector, and said servo sector detection A magnetic disk comprising a head position control circuit for detecting the number of a track being traced by a magnetic head based on a detection result of a path and driving the magnetic head so as to access a target track based on the detected track number Device head position control device. 2. A method according to claim 1, wherein the plurality of servo marks of the synchronization detecting section are shortened by a fixed length from the starting servo mark to the ending servo mark of the synchronizing detecting section. Head position control device for magnetic disk drive. 3. The servo mark of the synchronization detecting section is extended by a fixed length from the servo mark at the starting point to the servo mark at the ending point of the synchronization detecting section. Head position control device for magnetic disk drive. 4. The magnetic recording apparatus according to claim 1, wherein the servo sector detection circuit determines that a servo sector has been detected by detecting at least two consecutive servo marks among the plurality of servo marks of the synchronization detection unit. Head position control device for disk drive. 5. The servo sector detection circuit according to claim 1, wherein when all of the plurality of servo marks of the synchronization detection section are detected, a signal for permitting writing of data to the data area is supplied to a head position control circuit. A head position control device for a magnetic disk drive according to claim 1. 6. A magnetic head for recording / reproducing data on / on each circular track of a magnetic disk, wherein each circular track is divided into a plurality of sections along the circumference thereof for recording data with the magnetic head. A servo detecting section in which a plurality of servo marks having different lengths are recorded in advance in each servo sector, and a first pattern section having a first pattern having a different length for each track. And a second pattern unit having a second pattern unit connected to the first pattern unit and having a length set so that the sum of the lengths of the first pattern unit and the first pattern unit has a constant value; A magnetic disk provided with a track number portion having a track code portion indicating a track number, and a plurality of burst portions recording burst signals; When tracing, it is determined that the magnetic head has detected the servo sector based on the difference in the time length of the detection output of the magnetic head due to the difference in the length of each of the plurality of servo marks, and the magnetic head traces A sector detection circuit for detecting a track number based on the lengths of the first and second patterns of a track number portion of a servo sector of the track being accessed, and accessing a target track based on the detected track number. A head position control device for a magnetic disk drive, comprising a head position control circuit for driving a magnetic head. 7. The magnetic disk drive according to claim 6, wherein the length of the first pattern portion of the track number portion is the shortest in the outermost track and is gradually increased toward the inner track. Head position control device. 8. The head of the magnetic disk drive according to claim 6, wherein the length of the first pattern portion of the track number portion is the longest at the outermost track and is gradually reduced toward the innermost track. Position control device. 9. Servo sectors are provided between data areas for recording data with a magnetic head, each of which is formed by dividing a circular track of a magnetic disk into a plurality of tracks along the circumference thereof. Providing, on a magnetic disk, a synchronization detecting unit formed by recording a plurality of servo marks having different lengths in advance, a track number unit recording a track number in advance, and a plurality of burst units recording a burst signal; When the magnetic head traces, the servo sector detection circuit determines that the magnetic head has detected a servo sector based on the difference in the time length of the detection output of the magnetic head due to the difference in the length of each of the plurality of servo marks. The magnetic head based on the detection result of the servo sector detection circuit. Detecting a track number in the scan, the head position control method of a magnetic disk device comprising the step of driving the magnetic head to access the target track based on the detected track number. 10. The magnetic recording apparatus according to claim 9, wherein the plurality of servo marks of the synchronization detecting section are shortened by a fixed length from the starting servo mark to the ending servo mark of the synchronization detecting section. A head position control method for a disk drive. 11. The magnetic recording apparatus according to claim 9, wherein the plurality of servo marks of the synchronization detecting unit are extended by a fixed length from the starting servo mark to the ending servo mark of the synchronization detecting unit. A head position control method for a disk drive. 12. In the servo sector detection circuit,
10. The head position control method for a magnetic disk drive according to claim 9, wherein when at least two consecutive servo marks among the plurality of servo marks of the synchronization detecting section are detected, it is determined that a servo sector has been detected. 13. The servo sector detection circuit,
10. The head position of a magnetic disk drive according to claim 9, wherein a signal for permitting writing of data to said data area is supplied to a head position control circuit when all of the plurality of servo marks of the synchronization detecting section are detected. Control method. 14. Servo sectors are provided between data areas for recording data by a magnetic head, each of which is formed by dividing each circular track of a magnetic disk into a plurality of tracks along the circumference thereof. A synchronization detection unit formed by recording a plurality of servo marks having different lengths in advance, a first pattern unit having a first pattern having a different length for each track, and a first pattern unit connected to the first pattern unit; A second pattern having a second pattern whose length is set such that the sum of the lengths of the first pattern portion and the first pattern portion becomes a constant value;
Providing a pattern portion, a track number portion having a track code portion indicating a track number, and a plurality of burst portions on which a burst signal is recorded on the magnetic disk; and when the magnetic head traces the servo mark, the plurality of servos are provided. Based on the difference in the time length of the detection output of the magnetic head due to the difference in the mark length, it is determined that the magnetic head has detected the servo sector, and the magnetic head determines the number of the track number portion of the servo sector of the track being traced. Detecting a track number by a sector detection circuit based on the lengths of the first pattern and the second pattern; and driving the magnetic head to access a target track based on the detected track number. A head position control method for a magnetic disk drive. 15. The method according to claim 1, wherein the length of the first pattern portion of the track number portion is the shortest on the outermost track and is gradually increased toward the inner track.
5. The head position control method for a magnetic disk drive according to claim 4. 16. The length of the first pattern portion of the track number portion, the length being the longest at the outermost track, and gradually decreasing toward the inner track.
7. A head position control method for a magnetic disk drive according to claim 1. 17. A plurality of servo marks having different lengths are recorded in advance in a data area for recording data by a magnetic head, which is formed by dividing a circular track into a plurality of pieces along the circumference thereof. A magnetic disk provided with a servo detector having a synchronization detection unit formed in advance, a track number part in which a track number is recorded in advance, and a plurality of burst parts in which a burst signal is recorded. 18. The method according to claim 17, wherein the plurality of servo marks of the synchronization detecting section are shortened by a fixed length from the starting servo mark to the ending servo mark of the synchronization detecting section. Magnetic disk. 19. The apparatus according to claim 17, wherein the plurality of servo marks of the synchronization detection section are extended by a fixed length from the servo mark at the start point of the synchronization detection section to the servo mark at the end point. Magnetic disk. 20. Servo sectors are provided between data areas for recording data by a magnetic head, each of which is formed by dividing each circular track into a plurality of tracks along the circumference thereof,
A synchronization detecting section in which a plurality of servo marks having different lengths are recorded in advance in each servo sector; a first pattern having a first pattern having a different length for each track;
And a second pattern having a second pattern connected to the first pattern portion and having a length set so that the sum of the lengths of the first pattern portion and the first pattern portion has a constant value. A magnetic disk provided with a track number section having a track code section indicating a track number and a plurality of burst sections recording burst signals. 21. The magnetic disk according to claim 20, wherein the length of the first pattern portion of the track number portion is the shortest at the outermost track and gradually increases toward the inner track. 22. The magnetic disk according to claim 20, wherein the length of the first pattern portion of the track number portion is the longest at the outermost track and is gradually reduced toward the innermost track. 23. Servo sectors are provided between data areas for recording data with a magnetic head, each of which is formed by dividing a circular track of a magnetic disk into a plurality of tracks along its circumference, and each servo sector has Providing, on a magnetic disk, a synchronization detecting unit formed by recording a plurality of servo marks having different lengths in advance, a track number unit recording a track number in advance, and a plurality of burst units recording a burst signal; When the magnetic head traces, the servo sector detection circuit determines that the magnetic head has detected a servo sector based on the difference in the time length of the detection output of the magnetic head due to the difference in the length of each of the plurality of servo marks. The magnetic head based on the detection result of the servo sector detection circuit. Detecting the number of tracks in the over scan, a recording medium recording the head position control method of a magnetic disk device comprising the step of driving the magnetic head to access the target track. 24. Servo sectors are provided between data areas for recording data with a magnetic head, each of which is formed by dividing a circular track of a magnetic disk into a plurality of tracks along the circumference thereof. A synchronization detection unit formed by recording a plurality of servo marks having different lengths in advance from each other, a first pattern unit having a first pattern having a different length for each track; and a first pattern unit connected to the first pattern unit. A second pattern section having a second pattern whose length is set so that the sum of the lengths of the first pattern section and the first pattern section becomes a constant value, and a track number section having a track code section indicating a track number. And providing a plurality of burst sections on which a burst signal is recorded on the magnetic disk.
When the magnetic head traces the servo mark, it is determined that the magnetic head has detected a servo sector based on a difference in time length of a detection output of the magnetic head due to a difference in length of each of the plurality of servo marks. Detecting a track number by a sector detection circuit based on the length of the first pattern and the second pattern of the track number portion of the servo sector of the track being traced by the magnetic head; A recording medium recording a head position control method for a magnetic disk drive, the method including a step of driving a magnetic head to access a target track based on the information.