JPH0492209A - Magnetic disk and magnetic disk device - Google Patents

Abstract

PURPOSE:To accurately generate a position error signal by setting the magnetizing direction of the erasure part of a servo track at least on one side out of the servo tracks at both sides of a certain servo track oppositely to the magnetizing direction of the erasure part of the certain track. CONSTITUTION:The magnetizing direction of the erasure part of each servo track is set in the same direction in the servo tracks 41, 42, 45, and 46, respectively, and it is set oppositely to that direction in the servo tracks 40, 43, and 44. Also, a position where the magnetizing inversion part of each servo track is set differently from that where the magnetizing inversion parts of neighboring servo tracks are provided. The influence of crosstalk can be remarkably reduced by inverting the phases of the erasure part and the magnetizing inversion part at every two tracks. Also, since unrequired magnetic flux from the servo track flowing in a magnetic head can be negated with each other even when a magnetic head is floated in a servo area 33, the positioning of the magnetic head can be accurately performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic disk and a magnetic disk device.

Prior Art Conventional Servo method for positioning a magnetic head in a magnetic disk device - One known method is the data surface servo method, which will be explained using Fig. 4. Fig. 4 (A) shows a conventional magnetic disk FIG. Figure 4 (A>
In the figure, 1 is a data area, and 6 is a servo area provided between the data areas 10. Figure 4 (B) is Figure 4 (A)
FIG. 3 is an enlarged view of region Z indicated by the dotted line shown in FIG. Figure 4 (
In B) 2. 3. 4. A plurality of data tracks 5 are provided along the rotational direction of the magnetic disk and are provided in the data area 1, on which desired data is written or read. 7, 8° 9.10.11 are provided in the servo area 6. A servo track is a servo track provided along the rotational direction of a disk.4 Generally, a servo track is provided so as to be offset by half a track from a data track. In other words, if the magnetic head is flying over the data track accurately, the magnetic head will pass across the two servo tracks by the same width.
For example, the servo track 8 is provided on both the data track 2 and the data track 3, and the servo track 9 is provided on both the data track 3 and the data track number 4 so as to be shifted by half a track. Further, the servo truck is composed of a magnetization reversal section that generates a burst signal serving as position information, and an erase section that is magnetized in one direction without magnetization reversal and provided before and after the magnetization reversal section. That is, servo tracks 7, 8. 9°10.1
．． 1 are magnetization reversal parts 7a, 8a, 9a, respectively.
Erase parts 7b, 8b, 9b for IOa and lla.
, 10b, Ilb and erase section 7c, 8.
At this time, even if the servo tracks are sandwiched between servo tracks 9c, 10c, and lie, the magnetization directions of the erase portions of each servo track are all in the same direction. Further, the magnetization reversal portions of each servo track are provided at different positions in adjacent servo tracks.

For example, magnetization reversal parts 8a, 1 of servo track 8.10
The position where 0a is provided (the force provided on the same radial direction (magnetization reversal portion of servo track 7.9° 11?a, 9a, lla is provided is the magnetization reversal portion 8a, IOa) The magnetic disk device positions the magnetic head by reproducing this magnetization reversal portion with the magnetic head and obtaining a servo signal.

How to position the magnetic head will be explained below.

FIG. 5 shows a control block for positioning a general magnetic head. In FIG. 12 is a magnetic head for reading data and recording data. 15 is a flexure composed of a leaf spring, and flexure 1
A magnetic head 14 is attached to one end of the magnetic head 5 via a gimbal, and the other end is joined to an arm 16.

17 is an amplifier that amplifies the reproduction signal read from the magnetic disk or the recorded signal. 18 is an auto gain control circuit (hereinafter abbreviated as AGC circuit).
The circuit 18 makes the amplitude of the reproduced signal sent from the amplifier 17 constant on the inner and outer circumferences of the magnetic disk. However, in the section of the servo region, the AGC circuit 18 does not operate, and L419 is a low-pass filter, and the low-pass filter 19 blocks high frequency noise of the reproduced signal sent from the AGC circuit 18. 20 is a rectifier circuit, and the rectifier circuit 20 half-wave rectifies the reproduced signal from the low-pass filter 19. 421 and 23 are integrator circuits, and the integrator circuit 21 receives the waveform of the burst signal read out from the first magnetization reversal section. Integrate and convert the integrated value to a voltage value. Further, the integrating circuit 23 integrates the waveform of the burst signal read out from the second magnetization reversal section, and converts the integrated value into a voltage value. 22 and 24 are sample and hold circuits, respectively, and the sample and hold circuit 22 temporarily holds the voltage value output from the integration circuit 21. Further, the sample hold circuit 24 also temporarily holds the voltage value output from the integrating circuit 23. 25 is a comparison circuit, and the comparison circuit 25 is a sample and hold circuit 22.
The voltage values output from each of the magnetic heads 24 and 24 are inputted, and the voltage values are compared to create a position error signal indicating the positional deviation of the magnetic head from the track center. Reference numeral 26 indicates a compensation circuit 18 for compensating the position error signal. Reference numeral 27 indicates a VCM driver for driving a voice coil motor (hereinafter abbreviated as VCM).The operation of the control block will be explained below using a specific example.

Now, when the magnetic head 14 is reading data on the data track 4 shown in FIG. 4(B), the magnetic head 14 enters the servo area 6 and servo track 9.10.
move across. First, the magnetic head 14 passes over the magnetization reversal section 10a and outputs a first burst signal.Then, the magnetic head 14 passes over the magnetization reversal section 9a and outputs a second burst signal. 1st and 2nd
The burst signals are respectively input to amplifiers 17. AGC circuit 18
．． Low pass filter 19. It passes through the rectifier circuit 20 in order. The first burst signal is input to the integrating circuit 21, and the second burst signal is input to the integrating circuit 23. Then, the integration circuit 21 integrates the waveform of the first burst signal and converts the integrated value into a first voltage value.
The sample and hold circuit 22 temporarily holds the first integral value.

On the other hand, the integrating circuit 23 integrates the waveform of the second burst signal, converts the integrated value into a second voltage value, and outputs the second voltage value to the sample hold circuit 24. Temporarily hold the voltage value of 4
Next, the comparison circuit 25 compares the first voltage value and the second voltage value.

At this time, if the first and second voltage values are the same, it means that the width of the magnetization reversal part] Oa through which the magnetic head 14 has passed is the same as the width of the magnetization reversal part 9a, and the magnetic head 14 is placed exactly on the data track 4. This means that it is surfacing. Also, if the first voltage value is larger than the second voltage value (y), the width of the magnetization reversal section 10a through which the magnetic head 14 has passed is said to be wider than the width of the magnetization reversal section 9a through which the magnetic head 14 has passed. This means that the magnetic head 14 is flying above the data track 4 closer to the servo track 10.

That is, if the first voltage value is greater than the second voltage value, the comparator circuit 25 outputs a positive position error signal, and if the first voltage value is less than the second voltage value, the comparator circuit 25 outputs a positive position error signal. The circuit 25 outputs a negative position error signal. In response to this position error signal, the VCM driver 27 drives the VCM to move the arm 16 so that the magnetic head 14 flies above the data track 4.

Problems to be Solved by the Invention However, in the conventional configuration, when the magnetic head 14 is floating above the servo track 9, 10, side crosstalk occurs in which unnecessary magnetic flux from the servo track flows into the magnetic head 14. The amount of crosstalk that occurs (the longer the recorded signal is, the larger it appears). Therefore, assuming that the track 3 in Figure 4 (B) is accurately positioned, the ) (because the magnetization reversal part of the erase part that exists before and after the burst signal is long, and this magnetization reversal direction is all in the same direction on the servo track, 41. The crosstalk component is added and reproduced, and it is obtained by superimposing it on the servo signal as shown in Figure 4 (D). In this case, the magnetization reversal part of the burst signal is much denser than the erase part. Therefore, the burst signal component does not appear as a crosstalk component, and the waveform is a low frequency that occurs only at the start and end points of magnetization in the erase section.Also, since the direction of magnetization in the erase section is the same for each servo track, The received crosstalk components also have the same phase and are phase-added, increasing the number of components. Therefore, when the magnetic head 14 reproduces the magnetization reversal portion, the burst signal output from the magnetic head may be distorted. Therefore, the burst signal If the magnetic head is input to the integrating circuits 21 and 23 in a distorted state, an erroneous position error signal is output, resulting in a decrease in the positioning accuracy of the magnetic head.The present invention solves the above-mentioned conventional problems. The object of the present invention is to provide a magnetic disk and a magnetic disk device that can reduce the influence of side crosstalk and accurately position a magnetic head.

Means for Solving the Problem To achieve this object, the magnetization direction of the erase portion of at least one servo track on both sides of a certain servo track is opposite to the magnetization direction of the erase portion of the other photo track. I made it.

Operation: With this configuration, unnecessary magnetic fluxes from the erase portion of the servo track can be canceled out. Embodiment FIG. 1 is a diagram showing a magnetic disk in an embodiment of the present invention. In Figure 1 (A), 32 is the data area 3
3 is a servo area provided between the data areas 32. FIG. 1(B) is an enlarged view of the area indicated by the dotted line in FIG. 1(A). 35
．． 36. 37°38.39 is a data track provided along the rotational direction of the magnetic disk and provided in the data area 32, on which desired data is written or read.40. 41. 42. 43. 4
4°45.46 is a servo track provided in the servo area 33 and along the rotational direction of the disk. Generally, the servo track is provided so as to be offset by half a track with respect to the data track. In other words, if the magnetic head is flying over the data track accurately, the magnetic head will pass over the two servo tracks so as to straddle the same width. are data track 37 and data track 38
They are staggered by half a track so as to span both sides. Further, the servo track is composed of a magnetization reversal section that generates a burst signal serving as position information, and an erase section magnetized in one direction without magnetization reversal, which is provided before and after the magnetization reversal region. That is, servo tracks 40, 41, 42. 43. 44. 45. 46
are magnetization reversal parts 40a, 41a, and 42a, respectively.
, 43a, 44a, 45a, 46a are erased by the erase sections 40b, 41b.

4.2b, 43b, 44b, 45b,
46b and erase parts 40c, 41c, 42c,
43c, 44c.

It is sandwiched between 45c and 46c. At this time, the magnetization direction of the erase portion of each servo track is 41. 42. 45. 46 are respectively directed in the same direction, and the other servo tracks 40.43.44 are specialized in the opposite direction to said direction. Further, the magnetization reversal portions of each servo track are provided at different positions in adjacent servo tracks. for example
Magnetization reversal portion 41a of servo track 41, 43.45,
Force length servo track 40° 42 provided in the same radial direction from position 1 where 43a and 45a are provided
．． 44.46 magnetization reversal parts 40a, 42a.

The position where 44a and 46a are provided is the magnetization reversal part 41
a, 43a, and 45a in the same radial direction. Also, servo track 40°43.4
4 includes reversing portions 40d at the front and rear ends to make the magnetization direction of the erase portion opposite to the magnetization direction of the erase portion of other servo tracks.

43d and 44d are provided. FIG. 1C shows the adjacent servo track 41 where the magnetic head is not positioned when the magnetic head is positioned on the data track 36. 42
．． 43. The reproduced waveform of the crosstalk component received from 44 is shown for each track, and by reversing the direction of magnetization of the erase section, the phase of the crosstalk component can also be reversed. At this time, let the sum of the total amount of crosstalk received by the magnetic head from the side servo tracks be Vc, and the crosstalk patterns received from each servo track having a front magnetization reversal section and a rear magnetization reversal section Ca and Cb, respectively. If K is the crosstalk sensitivity that depends on L and the distance from the magnetic head, then V
c is V c =K O(C4s+Cat) / 2 +K
1. (C41+C41) 10K 2 (C41+C
41)+... (1), and due to the phase relationship of the crosstalk components, C42=-C44=-〇4m--
・1l=CaCas=-C4s=C41=-Ichiban=Cb, so (1) formula (yoVc= (KO/2-Kl- to 2+ to 3+-・1* (
Ca + Cb) ('2) and a In this case, KO>Kl>K2>K3>..., so the counting of equation (2) almost cancels out the erase part and magnetization reversal part for each Lt2 track. By reversing the phase, the influence of crosstalk can be extremely reduced. When the magnetic disk having the servo area 33 configured as described above is positioned with the magnetic head using the control block shown in FIG. Since the head 14 is floating above the servo area 33, the unnecessary magnetic flux from the servo track flowing into the magnetic head 14 cancels out each other, causing the burst signal to be distorted and a false position error signal to be generated, unlike in conventional magnetic disk drives. There is no output, and accurate positioning of the magnetic head 14 can be performed.
A), (B), (C), and (D), the magnetic head is on the data track 35. 36. 37. 38.
39 is a diagram showing the waveform of a burst signal when each position is positioned at 39. FIG. As can be seen from this figure, the burst signal is distorted in the conventional magnetic disk drive (it can be seen that the burst signal is not distorted in the magnetic disk drive of this embodiment). This is not a problem at all in the magnetic head positioning control system.In FIG. 2, the servo signal on the data track 35 is It shows exactly the same waveform as before; in data track 36, the rear burst is inverted, in data track 37, both bursts are inverted, and in data track 38, only all the bursts are inverted. . In this case, the servo signal is half-wave rectified by the rectifier circuit 20 shown in FIG. Also, each bit before and after the servo area for phase inversion is connected to an integrator circuit 21.
By excluding it from the integration interval in , there is no problem even if the phase is reversed, and since distortion due to crosstalk is canceled, accurate integral values for each burst signal can be obtained, and a good position error signal can be obtained. I can do it. Therefore, the position error signal formed based on the burst signal is not distorted, and the magnetic head can be accurately positioned.

In addition, in the servo area shown in Figure 1, the force that reverses the direction of magnetization every two to the opposite side (the same effect can be obtained by reversing the direction of magnetization every two as shown in Figure 3) In addition, if the number of servo tracks whose erase sections are magnetized in the same direction and the number of servo tracks whose erase sections are magnetized in the opposite direction are approximately the same, the crosstalk can be suppressed by a force that can suppress crosstalk (not an approximately equal number of servo tracks). It goes without saying that crosstalk can be suppressed compared to the conventional u% effect of the invention.The present invention is capable of controlling the magnetization direction of the erased portion of one servo track, if not internally of the servo tracks on both sides of a certain servo track. By setting the magnetization direction of the erased part of a certain servo track in the opposite direction, unnecessary magnetic flux from the erased part of the servo track can be canceled out, preventing the burst signal from being distorted and producing an accurate position error signal. Since the magnetic head can be created, the positioning of the magnetic head can be performed.

[Brief explanation of the drawing]

Figure 4 (A, ) is a plane diagram showing a magnetic disk used in a conventional magnetic disk device.
B) is an enlarged version of the same image. Figure 4 (C) shows an ideal burst signal. Figure 4 (D) shows a burst signal of a conventional magnetic disk drive. Figure 5 shows a typical magnetic disk drive. This is a diagram showing the control block. , 383 42.43°40 a. 5a, 46 42b, 4c, 4'lc. 34, 35. 36. 3 Toratsuku 40, 41° 46... Servo track a, 43a, 44a, 4 Turning parts 40b, 41b. 45b, 46b, 40 9... Data 44.45° 41a, 42 a... Magnetization anti-3b, 44b. 42c, 43 C1 C2 C2 C...Erase clothes d. d. d...Reversal part

Claims (2)

[Claims] (1) A magnetic disk in which a data area consisting of a plurality of concentric data tracks and a servo area consisting of a plurality of servo tracks provided at positions shifted by half a track with respect to the data tracks are arranged alternately. The servo track is composed of a magnetization reversal section and an erase section, and the magnetization direction of the erase section of at least one of the servo tracks on both sides of a certain servo track is opposite to the magnetization direction of the erase section of the certain servo track. A magnetic disk characterized by: (2) a magnetic disk in which a data area consisting of a plurality of concentric data tracks and a servo area consisting of a plurality of servo tracks provided at positions shifted by half a track with respect to the data tracks are arranged alternately; comprising a magnetic head that performs at least one of reading and writing data from and to a magnetic disk, and an actuator that moves the magnetic head substantially parallel to the disk, the servo track comprising a magnetization reversal section and an erase section;
A magnetic disk device characterized in that the magnetization direction of the erase portion of at least one of the servo tracks on both sides of a certain servo track is opposite to the magnetization direction of the erase portion of the certain servo track.