JPH08273316A - Servo pattern writing device - Google Patents

Abstract

PURPOSE: To keep a signal high quality and at the same time to minimize damage between a magnetic head and a magnetic recording medium by preventing erasure owing to the influence of the side fringing of the magnetic head in a magnetic disk device, keeping the S/N ratio of a servo signal better with the high density of a track interval and realizing the positioning of high accuracy and using a verifying servo head at the time of verification to optimize a levitation quantity. CONSTITUTION: This servo pattern writing device has an R/W gate control circuit 2, an R/W current control circuit 3, a servo signal R/W circuit 4, a positioning mechanism driving circuit 5 and an SPM rotational frequency control circuit 12, which are controlled by an STW control circuit 1, and the writing current of a servo pattern is controlled by controlling the current of the current source of an R/W-IC. Also, at the time of verification, a detachable block is used and a servo head 10 and a verifying servo head can be interchanged by a head movement mechanism and a servo head interchanging means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo pattern writing apparatus for writing position information used for controlling the positioning of a magnetic head on a magnetic recording medium mounted on a magnetic disk drive, and more particularly to a high-density magnetic disk drive. And a servo pattern writing device.

[0002]

2. Description of the Related Art Conventionally, a servo pattern writing device (hereinafter Servo Truck Wr) for writing positioning information (hereinafter referred to as a servo pattern) for positioning control of a magnetic head on a magnetic recording medium mounted in a magnetic disk device.
iter: described as STW), overwriting is performed to write a servo pattern on the surface of the magnetic recording medium without a gap.
At this time, magnetic flux leaks from the end of the core of the magnetic head,
Due to the so-called side fringing, part of the written servo pattern is erased when an adjacent track is written, resulting in an erased portion in the center of the recorded servo pattern. There is. When such an erase portion exists, there is a disadvantage that the signal-to-noise ratio (S / N ratio) of the servo signal deteriorates with the increase in the track interval, and high-precision positioning cannot be achieved. .

In order to realize high-precision positioning, it is necessary that the S / N ratio does not deteriorate even if the track spacing is increased, and erasure due to side fringing must be prevented.

Further, in the conventional STW, there is a possibility that an error may occur in the positioning accuracy of the magnetic head, that is, an interval between a plurality of tracks, due to a change in the effective write length of the magnetic head and a backlash in the positioning control mechanism. . Further, since the erasing operation for the target track and the servo pattern writing operation to the position information area in the target track are performed at different timings, the writing requires a long time.

[0005] For this reason, a technique which eliminates such a problem is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-29109.

This is due to the relationship between the magnetization reversal recorded on the magnetic recording medium of FIG. 7 and the write current waveform during servo track writing (in the figure, the upper side shows the state of magnetization reversal on the written magnetic recording medium). And the lower side shows the waveform of the current flowing in the magnetic head for recording the magnetization reversal).
Using a magnetic head having a core width twice or more, IP ₁ to
By a write current pattern shown in IP _4, S1 to S4
The servo pattern is written in the position information element area indicated by, and the arrow “→” in the figure indicates the position recognized as the track center when the written servo pattern is read. Further, the vertical solid line indicates the positive polarity magnetization reversal, and the vertical dotted line indicates the negative polarity magnetization reversal. It should be noted that FIG. 7 is illustrated in consideration of writing from top to bottom. In the figure, L _t is the track spacing, L _c represents the core width of the servo head.

[0007] Here, for example, n to
Assuming that you are going to write to n + 4 tracks,
A magnetization reversal occurs in n racks, current application is suppressed in the next n + 1 track, and a remaining magnetization reversal is erased (DC erasure) in −n + 2 track by −i DC current, and in n + 3 track in n + 3 track n
DC erasure is performed on the magnetic recording medium through a current of -i so as not to disturb the magnetization reversal generated at the +4 track. Then, the magnetization reversal is caused again in the n + 4 track.

By performing this repetition, erasure due to side fringing does not occur. Also,
When the time interval from the current 0 to -i or the time interval from -i to the current 0 requires 600 [ns] or more, the write current pattern corresponds to the existing read / write (R
This can be sufficiently realized by using an integrated circuit (hereinafter, referred to as R / W.IC) dedicated to ead / Write, and is an effective erase prevention means.

The time interval from the current 0 to -i or from -i to the current 0 depends on the standard value described in the data sheet of R / W IC (trade name: IC 32R2020R manufactured by SSI). It is a thing.

[0010]

SUMMARY OF THE INVENTION The above-described conventional STW
In (2), when servo information required for realizing a magnetic disk device having an ultra-high recording density required in the future is recorded, the magnetization reversal interval is further shortened. That is,
Write current 0 to -i or -i to current 0
The time to get to is shorter.

Here, if control is performed such that the write current applied to the magnetic head is set to 0 by the write gate signal, the current value of the write current cannot be changed in time, and an erroneous servo pattern is recorded on the magnetic recording medium. There is a risk of writing.

[0012]

According to the present invention, when writing position information used for positioning control of a magnetic head to a magnetic recording medium mounted in a magnetic disk device, the current value of a write current is controlled to be switched. In a servo pattern writing device that is controlled by a write gate of a writing / reading integrated circuit, a clock circuit that determines a timing when writing the position information, and a switching circuit that switches a current value of a writing current at a timing synchronized with the clock And is provided.

[0013] Further, there may be provided an opening / closing circuit for turning on the write gate prior to control of the current value of the write current and turning off the write gate after completion of the writing. May be controlled.

The magnetic recording medium further comprises a rotation speed switching means for writing the position information, the rotation speed being lower than that in normal use, and for confirming the writing result of the position information, the rotation speed being lower than that for the writing. And a first magnetic head for writing the position information, a second magnetic head for checking the written position information, and the first and second magnetic heads. Positioning means for positioning at the same track position.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing components of an embodiment of the present invention. In the STW according to the present embodiment, as shown in FIG. 1, a magnetic recording medium 14 rotationally driven by a spindle motor (hereinafter, referred to as SPM) 23 is incorporated in a housing 15, and A magnetic head for writing a servo pattern, that is, a servo head 10 is opposed to the head arm 9.

A positioning mechanism 8 for positioning and driving the head arm 9, a position sensor 7 for detecting the operation of the positioning mechanism 8, a positioning mechanism driving circuit 5 for positioning and driving the positioning mechanism 8, and a rotational drive for the SPM 23. An SPM drive circuit 13; an SPM rotation speed control circuit 12 for controlling the SPM drive circuit 13;
The servo signal R / W circuit 4 for writing / reading the servo signal by the reference signal, the reference signal R / W circuit 6 for writing / reading the reference signal by the reference head 11, and the R / W for the servo signal R / W circuit 4. R / W current control circuit 3 for controlling current and R / W for controlling servo signal R / W circuit 4 R / W gate
W gate control circuit 2 and this R / W gate control circuit 2,
The STW control circuit 1 controls the reference signal R / W circuit 6 and the SPM rotation speed control circuit 12.

The R / W gate control circuit 2 is an R / W · IC
And a switching circuit for switching the mode in which the write gate is always open during the writing of the servo track, and in other cases, the write gate is always closed.

The R / W current control circuit 3 is a circuit for supplying a constant positive and negative current and a small current to the R / W IC to the servo signal R / W circuit 4 when the write gate is open. The servo signal R / W circuit 4 is a circuit for flowing a current to the servo head 10. Under the control of the R / W gate control circuit 2 and the R / W current control circuit 3, a predetermined current is supplied to the servo head 10. Send out.

The positioning mechanism drive circuit 5 includes a position sensor 7
The servo head 10 integrated with the head arm 9 is positioned by the detection signal from the
Position 0 in place. The position sensor 7 detects the current position of the servo head 10, and the positioning mechanism 8 has a function of moving the servo head 10.

The reference head 11 is not integrated with the head arm 9, but the positioning mechanism drive circuit 5 is used.
Does not work, and is moved only in the loading / unloading (perpendicular to the surface of the magnetic recording medium 14) direction by another positioning mechanism (not shown).

The SPM rotation speed control circuit 12 sends a signal for switching the rotation speed of the SPM 23 to the SPM drive circuit 13 based on the control signal sent from the STW control circuit 1. This makes it possible to control the number of revolutions of the SPM 23, and when writing, the SPM2 can be controlled more than when it is rotated normally.
By reducing the number of rotations of 3, the sufficient time for current control is secured even in a high-density magnetic disk drive. Also,
Mechanical vibrations mainly caused by SPM at the time of writing can be reduced, and further confirmation of writing (hereinafter, Veri
In the case of fy: verify), conversely, by increasing the rotation speed of the SPM 23, the signal output can be increased and the time required for the verification can be shortened.

FIG. 2 is a magnetic recording medium according to an embodiment of the first invention (particularly a servo medium on which servo information is recorded).
FIG. 6 is a diagram showing the relationship between the magnetization reversal recorded above and the write current waveform at the time of servo track writing. The upper side in the figure shows the state of magnetization reversal on the written magnetic recording medium 14, and the lower side. Shows the waveform of the current flowing through the servo head 10 for recording the magnetization reversal. Further, L _t is the track interval, and L _c is the core width of the servo head.

Referring to FIG. 2, the write current pattern of this embodiment is different from the write current pattern of the conventional example (see FIG. 7) in that the write current is suppressed in the conventional example. Then, it means that a minute current is flowing. That is, the portion where the write current is “0” in FIG. 7 is “0 + Δi” in FIG. 2, and the minute current “Δi” flows.

In this embodiment, there are six magnetization reversals in each of the position information element regions indicated by S1 to S4, and each magnetic reversal is performed at 3600 revolutions per minute. 6 per track as information element area
Assuming that writing is performed 000 times, the allowable time for current control is about 230 [ns].

[0026] Here, by using a write current having a current waveform of IP _1, when attention is focused on a track servo pattern is written in the n-th, in track n in the track n-2, minute current does not cause a magnetization reversal “Δ
In the area corresponding to the position information element area S2 in which the DC erasing operation of the servo head is suppressed by flowing i ", the DC erasing operation is performed by applying the write current -i. In preparation for the writing of the servo pattern, the DC erasure is continued also in the position information element area S3 in which the servo pattern has already been written in the track n-2. Erase servo patterns that are out of range.

Next, in the succeeding position information element area S4, since a servo pattern is written in the immediately preceding track n-1, a very small current "Δi" that does not cause magnetization reversal so that the servo pattern is not erased. "
To suppress the DC erasing operation of the servo head. Further, in the immediately preceding track n-1, in the position information element area S1 subsequent to S4 in which the direct current has been erased,
The DC erase current changes from the current -i to + i, and further -i
The servo pattern is written with the repeated current waveform of returning to. Then, in the next position information element area S2, DC erasure is performed while holding the current -i.

As a result, at the end of the servo pattern writing area, the current value −i is the same as that of the next servo pattern writing area. Therefore, the servo pattern recorded on the magnetic recording medium has a core width of the servo head. Without being affected by "dimensional variation" and side fringing,
High quality servo patterns can be written.

FIG. 5 is a circuit diagram showing an example of the write current switching circuit section in the servo signal R / W circuit 4 of FIG.

Referring to FIG. 5, the write current switching circuit section inputs a switching signal from a terminal and outputs an R /
The current to the write current control terminal of the WIC is controlled. With this circuit, a current (small current "Δi") determined by the resistance value of the resistor R4 flows through the servo head 10. The terminal is an input terminal for write data.

The circuit elements used in the circuit of FIG.
R / W IC (trade name: IC 32R202 manufactured by SSI)
1R / 4SV), transistor Tr ₁ (trade name: NEC transistor 2SC639), capacitor C ₁ : 1
20 [pF], resistors R ₁ and R ₂ : 1 [kΩ], R ₃ :
50 [Ω] and R ₄ : 1 [MΩ].

FIG. 2 (upper side in the figure) shows the state of magnetization reversal on the surface of the magnetic recording medium in which all the operations of the servo track write have been completed. Further, an arrow “→” in the drawing indicates a position recognized as the track center when the written servo pattern is read. Further, in the drawing, the solid line in the vertical direction indicates the magnetization reversal of the positive polarity, and the dotted line in the vertical direction indicates the magnetization reversal of the negative polarity.

Next, a servo pattern writing operation in this embodiment will be described.

FIG. 3 is a flowchart showing the procedure of the write operation in the embodiment of the first invention.

Referring now to FIG. 3 and FIG. 1, first, the STW control circuit 1 issues a servo track write preparation start command to the positioning mechanism drive circuit 5 (S 10), and the servo head supported by the head arm 9. 10 is positioned at the writing start position via the position sensor 7 and the positioning mechanism 8. Further, the reference head 11
It is positioned at a predetermined position by another positioning mechanism (not shown) (S11).

Next, the STW control circuit 1 sends a rotation command of the SPM 23 to the SPM rotation speed control circuit 12. Therefore, the SPM rotation speed control circuit 12 sends a command to the SPM drive circuit 13 to rotate the magnetic recording medium 14 by the SPM 23 provided in the housing 15 (S12). And STW
When the SPM 23 reaches the predetermined number of revolutions, the control circuit 1 determines that the preparation for the servo track write has been completed (S13).

With the servo track write ready,
The STW control circuit 1 sends a reference clock write command to the R / W gate control circuit 2, the positioning mechanism drive circuit 5, and the reference signal R / W circuit 6 (S1).
4).

As a result, the write gate is opened by the R / W gate control circuit 2, and the servo head 10 uses the current output from the servo signal R / W circuit 4 under the control of the R / W current control circuit 3. Clock information is written on the magnetic recording medium 14. Then, the reference head 11 writes a reference clock on the magnetic recording medium 14 based on the written clock information. After writing, the write gate is closed, and the timing after writing is measured (S16).

If there is no abnormality in the timing of the reference clock, the STW control circuit 1 determines that the reference clock writing is completed (S16).

Upon completion of the reference clock write,
The STW control circuit 1 sends a servo track write command to R /
It is sent to the W gate control circuit 2 (S17).

At this time, the write current control has been initialized to a minute current state. As a result, the write gate is opened, and servo track write is executed by the servo head 10 (S18).

The servo track write (S18) will be described in detail below.

In S18, the R / W gate control circuit 2
Receives a servo track write command from the STW control circuit 1, informs the R / W current control circuit 3 that the write gate has been opened, and the STW control circuit 1 sends the write current to the R / W current control circuit 3. Send control signals and write data.

FIG. 4 is a diagram showing a relationship between a write current control signal and write data at the time of servo track write according to the first embodiment of the present invention.

Referring to FIG. 4, when the write current control signal is at "H" level, writing is possible (normal current flows), and when the write current control signal is at "L" level, writing is disabled. It becomes possible (a minute current Δi flows). The write current control signal and write data shown in FIG. 4 correspond to the terminals and terminals shown in FIG. 5, respectively. The write current control signal of FIG. 4 is input from the terminal of FIG. Write data is input from the terminal of FIG.

Referring again to FIG. 3 and FIG.
When receiving the write current control signal and the write data, the W current control circuit 3 sends a control signal synchronized with the signal read from the reference head 11 to the servo signal R / W circuit 4, and outputs the servo signal R / W circuit 4. Causes a write current to flow through the servo head 10 at a timing synchronized with the reference clock to cause magnetization reversal on the magnetic recording medium 14.

Then, when one servo track is written,
The current control state is returned to the minute current state at the timing synchronized with the reference clock. After that, when the STW control circuit 1 determines that the servo track write of one track is completed, it sends a command to close the write gate to the R / W gate control circuit 2.

As a result, the write gate is closed and the servo head 10 cannot execute the servo track write. At this time, the current value of the write current is controlled without opening and closing the write gate in the middle of writing for one round, thereby enabling faster write control. As described above, in this embodiment, since writing is controlled by current control, servo track writing can be performed without adverse effects due to noise generated during gate control. Then, this servo track write is repeated for a predetermined track.

The above is the servo track write (S18).
It is a detail of the process in.

Next, as processing after S18, the STW control circuit 1 determines that the servo track write has been completed by executing the servo track write for the predetermined track (S19).

Subsequently, the STW control circuit 1 sends to the SPM rotation speed control circuit 12 a start command for servo track write post-processing, that is, a command for stopping the SPM 23 rotation (S).
20). Therefore, the SPM rotation speed control circuit 12 stops the SPM 23 via the SPM drive circuit 13, and stops the rotation of the magnetic recording medium 14 (S21).

When the rotation of the SPM 23 stops, the STW control circuit 1 determines that the servo track write post-processing is completed. Then, the positioning mechanism drive circuit 5 drives the head arm 9 by the position sensor 7 and the positioning mechanism 8, and the servo head 10 is positioned at an initial retract (load / unload) position (not shown). Further, the reference head 11 is positioned at the initial retreat (load / unload) position (not shown) by another positioning mechanism (not shown) (S22).

As described above, when the post-servo track write processing is completed, a series of operations are all completed (S23).

Next, specific experimental data of the mode switching time by the current control of the current source of this embodiment and the mode switching time by the control of the write gate of the conventional example are shown in Table 1.
Shown in

[0055]

[Table 1]

According to Table 1, the switching time in each mode is shorter in this embodiment than in the conventional example, and by using the current control of the current source according to this embodiment, the servo pattern of higher recording density can be obtained. You can see that writing is possible.

Next, an embodiment of the second invention will be described.

FIG. 6 is a block diagram showing the outline of an embodiment of the second invention.

In this embodiment, the number of revolutions of the magnetic recording medium is written to the magnetic recording medium at a lower rotation speed during writing, and the number of revolutions of the magnetic recording medium is increased at the time of verifying than during normal use. In order to increase the signal output from the magnetic recording medium, a structure for replacing the servo track write and verify magnetic heads shown in FIG. 6 is added to the structure shown in FIG.

As shown in FIG. 6, the means for replacing the magnetic head includes a verifying servo head 21 and a detachable block which allows the servo head 10 or the verifying servo head 21 to be attached to and detached from the head arm 9. And a servo head replacing means 2 for attaching and detaching the servo head 10 or the verifying servo head 21 to and from the head arm 9 using the detachable block 18.
0, a head housing position 22 for housing the removed magnetic head, and a head moving mechanism 19 for carrying the removed magnetic head to the servo head replacement means 20 or the head housing position 22.

Referring to FIGS. 1 and 6, in this embodiment, first, when the STW control circuit 1a issues a verify start command to the positioning mechanism driving circuit 5, the servo supported by the head arm 9 is started. The head 10 is positioned at the reading start position by the positioning mechanism drive circuit 5 via the position sensor 7 and the positioning mechanism 8. At this time,
Prior to the movement of the magnetic head, the servo head replacing means 2
The value 0 indicates that the servo head 10 has been replaced with the verifying servo head 21.

Next, the STW control circuit 1a sends a command for rotating the SPM 23 to the SPM rotation speed control circuit 12. The SPM rotation speed control circuit 12 drives the SPM 23 in the housing 15 via the SPM drive circuit 13 to rotate the magnetic recording medium 14. STW control circuit 1a is SP
When it is determined that M23 has reached a predetermined number of rotations (higher rotation than at the time of servo track writing), the completion of verification preparation is recognized.

Next, the STW control circuit 1a sends a verify command to the R / W gate control circuit 2. As a result, verification by the servo head 10 becomes possible,
The magnetic information (servo information) written at the normal operation position 16 on the magnetic recording medium 14 is read. And ST
The W control circuit 1a uses the read result as shown in FIG.
Current pattern and servo head 1 shown in the lower part of FIG.
Compared with the servo pattern read from 0, it is confirmed (verified) whether or not the correct servo pattern is written on the magnetic recording medium 14.

Then, the above-described processing is repeated for a predetermined track. At that time, the track interval when the servo head 10 is positioned around the arrow “→” portion is also measured to confirm whether or not the moving interval of the magnetic head is accurate.

When the STW control circuit 1a determines that the verification has been completed for all of the predetermined tracks, it recognizes the completion of the verification and sends an SPM rotation stop command to the SPM rotation speed control circuit 12. Thereby, the SPM rotation speed control circuit 12 stops driving the SPM 23 in the housing 15 via the SPM drive circuit 13 and stops the rotation of the magnetic recording medium 14.

When the rotation of the SPM 23 stops, the STW control circuit 1a recognizes the completion of the verification, drives the positioning mechanism drive circuit 5 to drive the head arm 9 through the position sensor 7 and the positioning mechanism 8, and the servo head 10 is initially retracted. It is positioned at a (load / unload) position (not shown). Further, the reference head 11 is retracted to an initial retracting (loading / unloading) position (not shown) by another positioning mechanism (not shown).

Next, the servo head for verification 21 is replaced with the servo head 10 using the servo head replacing means 20.

First, when a servo head replacement command is issued, the STW control circuit 1a moves the servo head 10 from the initial retreat (load / unload) position (not shown) to the retreat position 17. The servo head replacing means 20 removes the servo head 10 from the head arm 9 using the detachable block 18 attached to the servo head 10.

Subsequently, the servo head 10 is moved to the head storage position 22 by the head moving mechanism 19, and then the verifying servo head 21 is moved again to the operating position of the servo head replacing means 20 by the head moving mechanism 19, It is attached to the arm 9 using a removable block 18.

When the verifying servo head 21 is replaced with the servo head 10, the servo head replacing means 20, contrary to the above-described method, uses the detachable block 18 attached to the verifying servo head 21. From the head arm 9 using the servo arm 2 for verification.
Remove 1.

Next, the verifying servo head 21 is moved to the head storage position 22 by the head moving mechanism 19, and then the servo head 10 is moved again to the operating position of the servo head replacing means 20 by the head moving mechanism 19. It is attached to the arm 9 using a removable block 18. Finally, the servo head 10 is moved from the retreat position 17 to the initial retreat position.

Further, according to the above-described method, at the time of verification, the SPM is rotated at a higher speed than at the time of servo track write.
In the case of using a method of driving a (spindle motor), by using a magnetic head having an optimum flying height with respect to the number of rotations, it is possible to output a precise signal from the magnetic recording medium. Further, by performing the verification with high accuracy, the performance of the magnetic disk device can be improved.

If the switching ratio of the number of rotations of the magnetic recording medium is about 1: 2, one magnetic head can be shared for writing and verifying.

[0074]

As described above, according to the STW (servo pattern writing device) of the present invention, by switching the current flowing through the magnetic head at high speed, erasure due to the influence of side fringing of the magnetic head does not occur. ,
It is possible to write a servo pattern having a higher recording density than before.

In order to write a servo pattern with a higher recording density, which cannot be switched in time, switching can be performed by lowering the rotation speed of the magnetic recording medium during writing and increasing the rotation speed of the magnetic recording medium during verification. become.

Further, according to the STW of the present invention, a sufficient time for current control can be ensured even in a high-density magnetic disk device by lowering the rotation speed at the time of writing a servo pattern than at the time of normal rotation. Also, at the time of writing, mechanical vibration mainly caused by the SPM (spindle motor) can be reduced, the S / N ratio of the servo signal is improved, and positioning with higher accuracy is possible.

Further, at the time of verification, by increasing the rotation speed of the magnetic recording medium, the verification time can be shortened and the signal output can be increased, and by replacing the magnetic head, the optimum rotation speed of the magnetic recording medium can be obtained. It is possible to obtain a high flying height and improve the accuracy of the output signal.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of an embodiment of a first invention.

FIG. 2 is a diagram showing the relationship between the magnetization reversal recorded on the magnetic recording medium according to the example of the first invention and the write current waveform during servo track writing.

FIG. 3 is a flowchart showing a procedure at the time of servo track writing in the embodiment of the first invention.

FIG. 4 is a diagram showing a relationship between a write current control signal and write data during servo track writing according to the first embodiment of the present invention.

FIG. 5 is a circuit diagram showing an example of a write current switching circuit section of the servo signal R / W circuit 4 of FIG.

FIG. 6 is a configuration diagram schematically showing an embodiment of the second invention.

FIG. 7 is a diagram showing a relationship between magnetization reversal recorded on a magnetic recording medium and a write current waveform at the time of servo track writing according to a conventional example.

[Explanation of symbols]

 1, 1a STW control circuit 2 R / W gate control circuit 3 R / W current control circuit 4 Servo signal R / W circuit 5 Positioning mechanism drive circuit 6 Reference signal R / W circuit 7 Position sensor 8 Positioning mechanism 9 Head arm 10 Servo Head 11 Reference head 12 SPM rotation speed control circuit 13 SPM drive circuit 14 Magnetic recording medium 15 Housing 16 Normal operation position 17 Retreat position 18 Removable block 19 Head moving mechanism 20 Servo head exchange means 21 Servo head for verification 22 Head storage position 23 SPM (Spindle motor)

Claims (5)

[Claims] 1. When writing position information used for positioning control of a magnetic head to a magnetic recording medium mounted on a magnetic disk device, switching control of a current value of a write current is performed by an integrated circuit for writing / reading the position information. In a servo pattern writing device controlled by a write gate, a clock circuit that determines a timing when writing the position information, and a switching circuit that switches a current value of a write current at a timing synchronized with the clock are provided. Servo pattern writing device. 2. The servo pattern writing apparatus according to claim 1, further comprising an opening / closing circuit that turns on the write gate prior to controlling the current value of the write current and turns off the write gate after the writing is completed. Characteristic servo pattern writing device. 3. The control by the write gate controls the current of a current source.
The described servo pattern writing device. 4. The servo pattern writing device according to claim 1, further comprising: a rotation speed switching unit for rotating the magnetic recording medium, wherein the rotation speed is reduced when writing the position information as compared with a normal use. A servo pattern writing device for reading the position information at a higher rotation speed than at the time of writing when confirming the writing result of the position information; 5. The servo pattern writing device according to claim 1, further comprising: a first magnetic head that writes the position information, and a second magnetic head that confirms the written position information. And a positioning means for positioning the first and second magnetic heads at the same track position.