JPS6366776A - Driving system for magnetic disk - Google Patents

Abstract

PURPOSE:To constantly correctly follow the eccentricity of a magnetic disk by providing adjacently more than two tracks for detecting the eccentricity having plural patterns for detecting the quantity of the eccentricity outside of the data recording area of the magnetic disk. CONSTITUTION:A magnetic head 2 moves to a position just before reaching the eccentricity detecting track TF01, the position information of all the patterns POF1-POF16 is detected from the position, further, the displacement from the pattern POF1 to other patterns POF2-POF16 is calculated and stored as eccentricity information by the eccentricity detecting track TF01. In the eccentricity information, the driving characteristic for the magnetic head 2 in the exciting phase of a step motor 7 when the magnetic head 2 is positioned to the eccentricity detecting track TF01 is included. Similarly, the driving characteristic of the magnetic head 2 in the exciting phase of the step motor 7 when the magnetic head 2 is positioned to the eccentricity detecting track TF02 is included. The average value of the patterns POF1-POF16 is calculated, a noise is removed, a phase difference is calculated to store as the final eccentricity information and the magnetic head is followed to the eccentricity of the magnetic disk.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a drive system for a magnetic disk device that uses a cartridge-type magnetic disk as a storage medium.

[Prior Art] There are various types of magnetic disk devices used as external storage devices in computer systems.
There is a magnetic disk device in which the magnetic disk used as a storage medium can be replaced.

In addition, storage media that can be attached to and removed from the drive device are stored in synthetic resin disk cartridges, and are handled in a protected state to prevent data errors due to dirt such as dust and fingerprints. .

In this way, in a magnetic disk device in which the storage medium can be replaced, when a disk cartridge is installed in the drive device, the magnetic disk is chucked onto the shaft (spindle) of the drive motor, and the magnetic disk is rotated in this state. ing.

Normally, when a disk cartridge is installed in a drive device, the spindle center of the drive motor does not exactly align with the spindle center of the magnetic disk stored therein, but is installed with a slight deviation. Therefore, the magnetic disk rotates in an eccentric state, and the positional relationship between the recording track formed concentrically with respect to the center of the magnetic disk and the magnetic head that reads and writes data to the magnetic disk changes.

One method for solving this problem is to form a servo track on one surface of the magnetic disk, on which servo data is recorded at the same track pitch as the recording track, and then to record the servo data on this servo track. Attach the servo head to be read to the same access member as the magnetic head for data read/write, drive the access member so that the servo head does not come off the servo track, and position the magnetic head on the recording track. is possible.

However, such a method is not effective when the number of magnetic disks attached to the same spindle in a disk cartridge is small. Moreover, the device configuration is complicated and the cost is high.

Conventionally, therefore, the following method has been used for disk cartridges in which the storage capacity per disk cartridge is relatively small.

That is, a servo pattern for positioning the magnetic head outside the data recording area of each recording track is formed, and thereby the magnetic head is positioned at the center position of the recording track at the location of the servo pattern ( so-called index burst servo). Therefore, even if the amount of eccentricity between the spindle of the magnetic disk and the spindle of the drive motor changes each time a disk cartridge is installed, the magnetic head can be positioned at the center of the recording track at the position where the servo pattern is arranged.

Further, one eccentricity detection track is set outside the data recording area of the magnetic disk, and 16 eccentricity detection patterns, for example, are formed at equal intervals on this eccentricity detection track. Then, eccentricity information indicating the eccentricity state of the magnetic disk is formed based on the feeding position of the magnetic head when each of these eccentricity amount detection patterns is detected. After positioning the magnetic head to the desired recording track.

Based on the eccentricity information, the magnetic head is moved to follow the eccentricity of the magnetic disk.

In this way, the magnetic head is positioned on the target recording track, and the magnetic head is moved so as to follow the eccentricity of the magnetic disk at that time.

Now, in many cases, in inexpensive magnetic disk drives with a relatively small storage capacity, a step motor is used as a drive source for a magnetic head.

This step motor can operate at an angle smaller than the step angle (microstep angle) by so-called microstep drive, and can therefore move the magnetic head minute by minute, which is useful for positioning the magnetic head as described above. It is possible to follow the eccentricity of the magnetic disk.

By the way, due to variations in the characteristics of the excitation coil of the step motor, the amount of operation of the step motor with respect to the drive current (microstep current) differs depending on the relationship between the excitation phases.

For example, in a step motor with 2-phase (4-phase) excitation of A (, A) and B (, B) phases, when the same drive current is applied with the A, B phases and B, A phase excited respectively. ,
For example, the actuation amount in the latter case may be larger on one side than the actuation amount in the former case.

Now, when detecting a pattern on a dummy track, the magnetic head is gradually moved to accurately detect the pattern position, so the drive characteristics of the magnetic head during the excitation phase of the step motor at that time are included. In this state, eccentricity information of the magnetic disk is formed.

Therefore, conventionally, when the magnetic head is moved based on this eccentricity information, if the excitation phase that positions the magnetic head on the track and the excitation phase when the eccentricity information is formed are different, the magnetic head will move. This has resulted in the inconvenience that the magnetic head cannot accurately follow the eccentricity of the magnetic disk and cannot accurately trace the track positioned at that time.

[Objective] The present invention has been made in order to eliminate the disadvantages of the prior art, and it is an object of the present invention to provide a drive method for a magnetic disk device that allows a magnetic head to always accurately follow the eccentricity of a magnetic disk. .

[Structure] In order to achieve this object, the present invention provides at least two adjacent eccentricity detection tracks in which a plurality of eccentricity detection patterns are formed outside the data recording area of a magnetic disk, The magnetic head is positioned on each eccentricity detection track to detect each of the patterns for detecting the amount of eccentricity, the average value is calculated for each detected value of the pattern for detecting the amount of eccentricity, and the average value is calculated based on the average value. The magnetic head is driven to follow the eccentricity of the magnetic disk.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a magnetic disk according to an embodiment of the present invention.

In the figure, recording tracks TRD are formed concentrically at a predetermined pitch on the magnetic disk 1, and two eccentricity detecting tracks are provided outside the recording tracks TRD for detecting the eccentricity of the magnetic disk 1. Truck TOFI, T
OF2 is formed. In addition, a burst pattern BPT for positioning the magnetic head at the center of the track is formed in each track corresponding to the index position IDX that serves as a reference for the rotational position of the magnetic disk 1.

In the eccentricity detection tracks TOFI and TOF2, patterns POFI to POF 16 for detecting eccentricity, which are two burst patterns for detecting eccentricity, are arranged at equal intervals.
Six pieces are formed. Furthermore, the pattern POFI also serves as the burst pattern BPT.

An example of the pattern POFI-16 for detecting the amount of eccentricity is shown in FIG. 2. In this figure, assuming that the magnetic disk 1 is stationary, the magnetic head moves from left to right.

In the figure, a pattern POFI-POF16 for detecting eccentricity in the eccentricity detection track TOFI is formed by burst pattern PTI and burst pattern PT2, and burst pattern PT2 and burst pattern PT3
As a result, patterns POFI to POF16 for detecting the amount of eccentricity in the track TOF2 for detecting eccentricity are formed.

Here, burst pattern PTI and burst pattern P
T3 is the same magnetization pattern, and the burst pattern P
T2 is a magnetization pattern opposite to burst pattern PTI and burst pattern PT3, and burst pattern PTI, PT2 . The magnetization strengths of PT3 are made equal. Therefore, the burst patterns PTI, PT
The polarity of the signal obtained from the magnetic head 2 is opposite when detecting the burst pattern PT2 and when detecting the burst pattern PT2.

Furthermore, the burst pattern BPT for positioning the magnetic head at the center of the track is based on these burst patterns PTI, PT2 . It is similar to PT3.

Note that in this case, the first recording track TRDI is not divided by the burst pattern PT3.

In order to maintain a distance between the eccentricity detection track TOF2 and the recording track TRDI, a dummy track TDM is provided between the eccentricity detection track TOF2 and the recording track TRDI.
is formed. Furthermore, the dummy track TDM may be removed.

Therefore, if the reproduction outputs of the magnetic head 2 are equal when detecting the burst pattern PTI and the burst pattern PT2, the magnetic head 2 is positioned at the center of the eccentricity detection tracks TOFI and TOF2 at that position. Similarly, when the reproduction outputs of the two burst patterns forming the burst pattern BPT are equal, the magnetic head 2 is at the position of the index IDX,
It will be positioned at the center of the recording track TRD.

FIG. 3 shows an example of an access mechanism for the magnetic head 2. As shown in FIG.

In the figure, magnetic heads 2 are provided on two surfaces of a magnetic disk 1, and are attached via a gimbal mechanism 3 to a carriage 4 that moves in the radial direction of the magnetic disk 1.

The shaft output of a step motor 7 is transmitted to the carriage 4 by a transmission mechanism consisting of a rack 5 and a pinion 6.

Further, 8 is a disk cartridge housing the magnetic disk 1, and 9 is a spindle of a motor for rotationally driving the magnetic disk 1. The magnetic disk 1 and the spindle 9 are coupled and released by a chucking mechanism (not shown).

Now, the step motor 7 is A (, A), B (, B
), the A and B phases are equipped with two sets of excitation coils (see Figure 4 (a) and (b)).
) is applied, and the step motor 7 rotates counterclockwise in FIG. 3. The step motor 7 rotates once in one cycle of this drive current.

In this case, when the step motor 7 rotates once, the magnetic head 2 moves a distance four times the track pitch of the recording track TRD. Furthermore, when a drive current with a polarity opposite to that shown in the drawing is applied, the step motor 7 rotates in the opposite clockwise direction.

However, in Fig. 4(a), the positive polarity part of the drive current is applied to the A-phase drive coil, and the negative polarity part of the current is applied to the A-phase drive coil as a positive polarity current. Ru. Also, when the drive current is applied to the A-phase drive coil, no drive current is supplied to the A-phase drive coil, and conversely, when the drive current is applied to the A-phase drive coil, the A-phase drive coil is not supplied with the drive current. No drive current is supplied to the drive coil.

Similarly, in the same figure (b), the positive polarity part of the drive current is applied to the B-phase drive coil, and the negative polarity part of the current is applied to the 1-phase drive coil as a positive polarity current. Also, when the drive current is applied to the B-phase drive coil, the drive current is not supplied to the 1-phase drive coil, and conversely, when the drive current is applied to the 1-phase drive coil, No drive current is supplied to the B-phase drive coil.

On the other hand, when the magnetic disk 1 is driven to rotate, the magnetic disk 1 rotates eccentrically because the center of the magnetic disk 1 and the center of the spindle 8 are misaligned.

The eccentricity is such that it draws a sine curve with period T and amplitude a, as shown in FIGS. 5(a) and 5(b), for example. However, in this case, the child direction of the eccentric displacement is taken toward the outer circumference of the magnetic disk 1.

Here, the period T is the rotation period of the magnetic disk 1,
Index I, which is a reference for the rotational position of magnetic disk l
It is equal to the generation period of the index signal Sx obtained by detecting DX. Further, the amount of eccentricity is not necessarily zero based on the rotational position of the magnetic disk l, and the timing of generation of the index signal SX and the state of eccentricity are out of phase.

Now, in order to make the magnetic head 2 accurately follow the recording track TRD on the magnetic disk 1 which is eccentric in this way,
The magnetic head 2 may be moved to follow the eccentricity of the magnetic disk 1.

For example, considering that the magnetic head 2 is positioned on the recording track TRD where the rotational position of the step motor 7 is 90 degrees, when the magnetic disk l is eccentric as shown in FIG. After rotating the step motor 7 counterclockwise from its positioning rotational position by an amount of rotation corresponding to the distance from to the peak of eccentricity in the child direction, from the peak of eccentricity in the child direction to the peak of eccentricity in one direction. The step motor 7 is rotated clockwise by a distance corresponding to twice the amplitude of the eccentricity, and then the step motor 7 is returned from that rotation position to the positioning rotation position (i.e. 90 degrees), and then This can be repeated in synchronization with the rotation of the magnetic disk 1 (see FIG. 6).

Therefore, when the magnetic head 2 follows the eccentricity of the magnetic disk 1 in this way, the step motor 7 repeatedly operates while being synchronized with the rotation of the magnetic disk 1 and being reversed by an amount of rotation equivalent to twice the amplitude of the eccentricity. be done.

That is, as shown in FIG. 6, when the rotational position of the step motor 7 is displaced from the rotational position Aa to the rotational position Ab when following eccentricity, the voltage applied to the A and B phase drive coils of the step motor 7 is The driving current is as shown in FIGS. 7(a) and 7(b).

Note that the manner of displacement of the step motor 7 is uniquely determined in accordance with the amplitude of the eccentricity of the magnetic disk 1 and the phase shift from the generation timing of the index signal Sx.

Therefore, as shown in FIGS. 8(a) to 8(d), by changing the drive current applied to each drive coil in synchronization with the generation timing and period of the index signal SX, the eccentricity of the magnetic disk 1 can be adjusted. magnetic head 2 to follow
is displaced.

In this way, the magnetic head 2 can follow the eccentricity of the magnetic disk 1 and can be accurately positioned on the recording track TRD.

FIG. 9 shows a control system of a magnetic disk device according to an embodiment of the present invention. Note that the control system for the rotation system and automatic attachment/detachment system of the magnetic disk 1 is omitted in the figure.

In the figure, the reproduction signal of the magnetic head 2 is amplified via a head amplifier 21 and then sent to a burst detection circuit 2.
2 and data read/write circuit 23.

The burst detection circuit 22 generates two different burst patterns PT1 . PT2. identify the PT3 and set their playback level to the burst level signal BLI.
, BL2 are output to the control unit 24.

The data read/write circuit 23 demodulates the reproduction signal of the magnetic head 2 into reproduction data and outputs it to the control section 24, and also modulates the recording data output from the control section 24 to form a recording signal. is output to the magnetic head 2 via the head amplifier 21 and recorded on the magnetic disk 1.

The index sensor 25 detects the index IDX of the magnetic disk 1, and its detection signal is waveform-shaped by a waveform shaping circuit 26 and then applied to the control unit 24 as an index signal Sx.

The microstep circuit 27 outputs drive current data for microstep driving the step motor 7 to an angle (rotation position @) specified by the control unit 24, and the output data is sent to the step motor drive circuit 28.
has been added to.

The phase switching circuit 29 is for switching the excitation phase of the step motor 7 to the excitation phase corresponding to the angle data designated by the control unit 14, and the switching command signal is applied to the step motor drive circuit 28. .

The step motor drive circuit 28 uses the drive current data output from the microstep circuit 27 and the phase switching circuit 2.
The phase of the step motor 7 is switched based on the switching command signal outputted from the step motor 9, and a drive current is applied to each exciting phase to be excited at that time.

Further, the external interface circuit 30 is used for exchanging data between the control unit 24 and an external host device or the like that uses this a-disk device.

With the above configuration, the control section 24 positions the magnetic head 2 by the following process.

That is, when the disk cartridge 8 is installed, the process shown in FIG. 10 is first executed to load the magnetic disk 1.
form eccentricity information.

First, the carriage 4 is brought into contact with a part of the housing of the drive device (not shown) located in the opposite direction to the spindle 9,
Properly position the carriage 4 to the home position Process 1
01) In that state, the position data of the carriage 4 is cleared to 0.

Next, eccentricity information is detected using the eccentricity detection track TFO1 (processing 102).

In this process 102, first, the carriage 4 is moved to a position immediately before the magnetic head 2 arrives at the eccentricity detection track TFOI, and from that position, the burst level signal BLI is
, BL2, the carriage 4 is gradually moved toward the inner circumference of the magnetic disk 1, and the burst level signal B is
L1. The position where the levels of BL2 are equal is detected, and the generation timing of the index signal SX and the burst level signal [3L1. Due to the time difference with the detection timing of BL2, the burst level signal B
Identify the pattern POFI-POF16 from which LI and BL2 were obtained. Then, apply this to all patterns POFI~PO
This process is repeated until the position information of F16 is detected.

Furthermore, from pattern POFI to other patterns POF2~
The displacement up to the POF 16 is calculated and stored as eccentricity information based on the eccentricity detection track TFOI. The eccentricity information stored in this way includes the drive characteristics of the magnetic head 2 in the excitation phase of the step motor 7 when the magnetic head 2 is positioned on the eccentricity detection track TFO1.

Next, eccentricity information is detected using the eccentricity detection track TFO2 (process 103).

In this process 103, the burst level signal BLI is generated from the position at the end of process 102, similarly to process 102.

The carriage 4 is gradually moved toward the inner circumference of the magnetic disk l while referring to BL2, and the burst level signal BL is
The position where the levels of I and BL2 are equal is detected, and the burst level signal BLI is determined based on the time difference between the generation timing of the index signal Sx and the detection timing of the burst level signals BLI and BL2 at that position.
, BL2 are identified, and this process is repeated until the position information of all the patterns POFI-POF16 is detected. and.

From pattern POFI to other patterns POF2 to POF1
Calculate the displacement up to 6 and use this as the eccentricity detection track TF.
It is stored as eccentricity information due to O2. The eccentricity information stored in this manner includes the drive characteristics of the magnetic head 2 in the excitation phase of the step motor 7 when the magnetic head 2 is positioned on the eccentricity detection track TPO2.

Then, the average value of each pattern POFI to POF16 of the eccentricity information obtained in this way is calculated (process 104), and noise is removed from the average value of the eccentricity information by performing smoothing processing using Laplace transform ( Process 105) Therefore, at the end of Process 105, the magnetic head 2 is moved to the eccentricity detection track TFO.
The eccentricity information includes the average driving characteristics of the magnetic head 2 in the excitation phase of the step motor 7 when the magnetic head 2 is positioned at the I and TFO2 positions.

With the noise removed in this way, the amplitude of eccentricity and the phase difference from the generation timing of index signal Sx are calculated (process 106) and stored as final eccentricity information.

Note that the eccentricity detection tracks TFOI and TFO2 are determined based on the eccentricity information obtained in processing 102 and processing 103, respectively.
The magnetic head 2 may be moved to follow the eccentricity of the magnetic head 2, and the eccentricity information obtained in processing 102 and processing 103 may be corrected based on the levels of the burst level signals BLI and BL2 in each of the patterns POFI to POF16 at that time. can.

Now, when actually accessing the target recording track TRD, the control unit 24 performs the process shown in FIG.
control. \That is, when the target track number is input from the host device (process 201),
The amount of movement to the target track is calculated based on the position information of the magnetic head 2 at that time, and the magnetic head 2 is moved to the target track (process 202). At this time, the magnetic head 2 is positioned so that the levels of the burst level signals BLI and BL2 are equal when the burst pattern BPT is detected.

Then, the rotational position of the step motor 7 at that time,
Based on the eccentricity information stored in advance, data for eccentricity tracking is calculated according to the procedure described above (process 203
).

In this process 203, one period of eccentricity is divided into 16 based on the generation timing of the index signal Sx.

Angle data DAG (1) at each timing
- Form a DAG (16) and store it as shown in FIG.

Then, the angle data DAC(1) to DAC(16) are sequentially outputted to the microstep circuit 27 and the phase switching circuit 29 every 1/16 cycle of the rotation of the magnetic disk l based on the generation timing of the index signal SX. , operates the step motor 7, thereby controlling the magnetic head 2 to follow the eccentricity of the magnetic disk 1.

In this way, in this embodiment, by calculating the average value of the eccentricity information obtained from each of the two eccentricity detection tracks, the average value of the drive characteristics of the magnetic head in two different excitation phases is calculated. Since the eccentricity information is obtained, the magnetic head can be made to appropriately follow the eccentricity of the magnetic disk without being affected by variations in the drive characteristics of the magnetic head due to differences in the excitation phase of the step motor.

In the above-described embodiment, two eccentricity detection tracks are provided, but they may be provided as many as the number of phase switching states of the step motor. In that case.

This makes it possible to further reduce the influence of variations in the drive characteristics of the magnetic head due to differences in the excitation phases of the step motors.

Further, the eccentricity detection track may be provided on the innermost circumference of the recording track.

Further, in the above embodiment, a step motor with two-phase (four-phase) excitation is used, but a step motor with a different number of excitation phases can also be used.

[Effects] As described above, according to the present invention, at least two eccentricity detection tracks each having a plurality of eccentricity detection patterns formed outside the data recording area of a magnetic disk are provided adjacently. Position the magnetic head on each track for eccentricity detection, detect each pattern for detecting the amount of eccentricity, calculate the average value for each detected value of the pattern for detecting the amount of eccentricity, and then calculate the magnetic head based on the average value. Since the magnetic head is driven to follow the eccentricity of the disk, it is not affected by variations in the drive characteristics of the magnetic head due to differences in the excitation phase of the step motor, and the magnetic head can be driven appropriately to the eccentricity of the magnetic disk. It has the advantage of being able to be followed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating a magnetic disk according to an embodiment of the present invention, FIG. 2 is a schematic diagram illustrating an example of a burst pattern, and FIG. 3 is a schematic configuration diagram illustrating a magnetic head drive mechanism. FIG. 4 is a waveform diagram showing an example of driving a step motor, FIG. 5 is a waveform diagram showing an example of eccentricity of a magnetic disk, and FIG. 6 is a schematic diagram showing an example of operation of a step motor.
Figure 7 is a waveform diagram showing the operating range of the step motor when the magnetic head follows the eccentricity of the magnetic disk, and Figure 8 shows an example of the operation of the step motor when the magnetic head follows the eccentricity of the magnetic disk. 9 is a block diagram illustrating the control system of a magnetic disk drive, FIG. 10 is a flowchart illustrating an example of processing when obtaining eccentricity information, and FIG. 11 is an example of processing for moving the magnetic head. The flowchart, FIG. 12, is a signal arrangement diagram showing an example of angle data. 1...Magnetic disk, 2...Magnetic head, 4...
Carriage, 7... Step motor, 22... Burst detection circuit, 24... Control unit, 27... Micro step circuit, 28... Step motor drive circuit, 29... Phase switching circuit, TFOI , TFO2...
Eccentricity detection track, POFI-POFI6...pattern, PTI-PT3...servo pattern. 7・-1'-3, Agent Patent Attorney Crest 1) Makoto)・／゛Figure 1Figure 2RDIFigure 3Figure 4Figure 5Figure 6Figure 7

Claims (1)

[Claims] In the drive system of a magnetic disk device, a magnetic disk is housed in a cartridge and has one servo pattern for head positioning formed on each track, and the magnetic head is driven by a drive means using a step motor. At least two eccentricity detection tracks each having a plurality of eccentricity detection patterns formed outside the data recording area are provided, and a magnetic head is positioned on each eccentricity detection track to detect the eccentricity detection patterns. , and calculates an average value for each detected value of the pattern for detecting the amount of eccentricity, and drives the head to follow the eccentricity of the magnetic disk based on the average value. Disk device drive method.