JP4268665B2 - Servo tracking pattern recording device - Google Patents

Description

The present invention relates to a servo tracking pattern recording apparatus having a magnetic transfer head for writing a master disk pattern on which a magnetic transfer pattern, which is a servo tracking pattern to be written on a magnetic disk, is written on a magnetic disk by a magnetic transfer system. The present invention relates to a read head and a write head that read and write original data and that can be positioned with high accuracy, and that the length of the magnetic transfer signal in the circumferential direction can be shortened.

  In magnetic transfer technology, for example, a burst signal, an address information signal, a reproduction clock signal, etc., which are servo signals, are recorded in a preformat recording on a magnetic disk medium (hereinafter referred to as a medium) of a magnetic recording device such as a hard disk drive. The master disk on which these pieces of information have been recorded is brought into contact with the medium to be preformatted and the contents are transferred by applying a magnetic field. Thereafter, this medium is incorporated into the magnetic recording device, and a final servo tracking pattern is written based on the preformat recorded signal in a self-test.

  As a result, when writing a servo tracking pattern, the productivity can be improved compared to using an expensive dedicated device that writes a servo tracking pattern with a precisely controlled magnetic head called a servo track writer. Is expected to be possible.

  FIG. 16 is a cross-sectional view along the track direction showing a state in which DC erase is performed to initialize the medium in such a magnetic transfer technique. This DC erase is performed by applying a DC excitation magnetic field to a medium.

  In the figure, 1 is a medium composed of a medium body 1b and a magnetic layer 1a formed on the surface thereof, and 2 is an arrow indicating the direction of an external magnetic field applied during DC erase.

  FIG. 17 is a diagram showing how magnetic transfer is performed. In FIG. 17, reference numeral 3 denotes a master disk composed of a non-magnetic substrate 3b and a magnetic body 3a formed on one main surface thereof. It is an arrow showing the direction of the external magnetic field to apply.

Hereinafter, a conventional magnetic transfer method will be described with reference to a flowchart shown in FIG.
First, as shown in FIG. 16, a magnetic field is applied to the medium 1 in the circumferential direction to perform DC erase to align the magnetization direction of the magnetic layer 1a in the same direction as the arrow 2 (see step 201).

  Usually, the media has already been DC erased when it is delivered from the media manufacturer to the hard disk drive manufacturer. However, the direction of magnetization may differ from the intended direction of the hard disk drive manufacturer. Initialization by DC erase is necessary.

  FIG. 19 shows a dedicated head used at the time of the DC erase, which is different from the original head for reading / writing data used after the hard disk drive is completed.

  This head 10 is obtained by attaching a yoke 8 to a permanent magnet 9 and has an arcuate gap 8a. The reason why the gap 8a is formed in an arc shape is that the locus of the head for reading and writing data draws an arc on the medium.

  As shown in FIG. 19, the head 10 is fixed at a position covering from the inner periphery to the outer periphery of the medium, and the DC erase is performed by rotating either the head 10 or the medium 1 one or more times around the media center. Do. The direction of rotation may be left or right. At this time, the distance between the magnet 9 and the medium 1 is 0.5 mm to 2 mm, and a signal detected from the medium on which the magnetic transfer is actually performed is confirmed and determined based on the characteristics. This distance depends on the holding force of the media, the strength of the magnet, the shape of the pattern, and the like.

  Next, a master disk 3 having a pattern made of a magnetic material (any magnetic material such as Co can be used) 3a on the nonmagnetic substrate 3b is obtained (see step 202). This pattern is shown in FIG. 17, and the striped portion 3a is a region where a magnetic material is formed. Similar to the semiconductor device, this pattern is formed by a photolithography process using a photomask. Step 202 and step 201 may be executed simultaneously, or step 202 may be executed first.

  Next, the information recording surface of the master disk 3 and the magnetic layer side of the medium 1 are brought into contact as shown in FIG. 17 (see step 203), and the head having the same shape as that used in the DC erase (see FIG. 18). ) 10 is used to apply a magnetic field in a direction opposite to the direction in which the medium 1 is DC erased (see step 204). At this time, since the magnetic field in the vicinity of the magnetic body on the master disk passes through the magnetic body, the magnetization of the media surface in the vicinity of the magnetic disk is not reversed. . In FIG. 17, the portion where the magnetic flux is drawn between the magnetic bodies 3 a is a portion without the magnetic body.

  FIG. 20 shows servo signals magnetically transferred to the medium 1 in this way, and 100 to 200 lines are formed so as to draw an arc from the inner periphery to the outer periphery of the medium. The number of servo signals generally increases with an increase in TPI (Track Per Inch).

  Next, the medium thus magnetically transferred is incorporated to complete the hard disk drive. A hard disk drive includes one or more media for magnetic recording, a motor for rotating the media, a rotor arm having one or more write heads and read heads for reading and writing data, and the rotor A driving device for driving the arm; a circuit for writing a signal; and a circuit for reading the signal. At least one magnetically transferred medium is incorporated into the magnetic recording apparatus according to the specifications of the apparatus (see step 205).

  FIG. 21 is a schematic view showing a state in which the cover of the completed hard disk drive is opened, and is composed of read and write heads provided in close proximity to each other for reading / writing data from / to a recording disk (medium) 1. The head 14 is rotatably installed with respect to the pivot center 12 within the range of the inner periphery and the outer periphery of the medium 1 by the rotor arm 13.

  FIG. 22 shows a signal obtained by reading the magnetized pattern with a read / write head. The contents relating to this magnetic transfer are described in Patent Document 1 ("Recording Method of Master Information Carrier and Master Information Signal on Magnetic Recording Medium").

  However, the master disk used for magnetic transfer has a technical limit of about 0.5 μm for both the width of the magnetic part and the interval between the magnetic parts in the production process. Therefore, the frequency of the pattern is usually That is, when the tracking pattern is recorded with a magnetic head by a servo track writer, the frequency is about 1/5 of the frequency of the servo tracking pattern of the magnetic recording apparatus.

  Accordingly, when the magnetization pattern formed by the magnetic transfer method is used as the final pattern of the magnetic recording apparatus, the tracking pattern occupancy in the data area is increased, so that the magnetic transfer signal is only used as a temporary servo tracking pattern.

  Further, since the master disk has a wide width for both the magnetic part and the non-magnetic part and cannot use the burst signal used in the magnetic recording apparatus, a phase control signal as shown in FIG. 23 is used instead. . This phase control signal is composed of three types of patterns P1, P2, and P3 and digital signal P4, and P1, P2, and P3 each have 20 to 30 bits (20 to 30 for both magnetic and non-magnetic parts). The total length is 60 to 90 bits. On the other hand, the burst pattern of the servo tracking pattern of a normal magnetic recording apparatus is about 60 bits, and the phase control signal tends to be longer. Therefore, the phase control signal is used as a temporary signal, and a servo tracking pattern actually used by the completed hard disk drive is written by self-servo writing (see step 206).

  This self-servo write is a temporary servo tracking pattern transferred by magnetic transfer, read by a data read / write head provided in the completed hard disk drive itself, and based on this, the servo system of the drive itself is used. The positioning of the data read / write head is controlled and the final servo tracking pattern is written.

  A method of performing self-servo writing using such a phase control signal as a temporary signal is described in Patent Document 2 ("Self-servo writing method of disk drive and embedded reference pattern used therefor").

  However, the phase control by magnetic transfer is greatly affected by electrical noise, and when the magnetic recording apparatus becomes a high TPI (Track Per Inch), there is a problem in the head control in the current phase control signal bit length and signal processing method. there is a possibility.

  Further, since the phase control pattern using the magnetic transfer method has a long pattern length, the limit of the number of servo tracking patterns written on the medium is about 350, which is not so large.

  Further, Patent Document 3 (“Magnetic Disk, Magnetization Pattern Forming Method and Magnetic Disk Device”) introduces a method of performing magnetic recording in the radial direction of the medium. This introduces a method for writing a burst signal which is a part of a servo tracking signal.

  The servo tracking signal includes a digital signal portion in addition to the burst signal. The digital signal section includes a SYNC signal section for adjusting the reading timing, an AGC signal section for automatically determining an amplification factor, and a SAM (Servo Address Mark) for determining that the signal having the signal section is a servo tracking signal. ) It consists of information such as a signal part and a track number part indicating the track number. In addition, considering the tracking mechanism of a conventional magnetic recording device, the digital signal section is magnetically recorded in the radial direction of the medium. It is impossible to recognize a tracking signal or to read track number data, and it is necessary to record these signals in the circumferential direction. Therefore, since the servo tracking signal always has a digital signal portion that needs to be recorded in the circumferential direction (track direction), when the burst signal portion is to be magnetically recorded in the radial direction, 2 in the circumferential direction and the radial direction. It is necessary to make a kind of record. However, this Patent Document 3 does not describe a method for simultaneously writing these two types of signals.

As a method of writing such two types of signals, a method of dividing the digital signal portion and the burst signal portion and recording them on two master disks and writing these two types of signals by writing twice can be considered. In that case, the alignment of the two signals becomes a problem. These two signals are required to have a radial shift amount within several nanometers, and it is very difficult to do this in a process that is currently in practical use. Further, when writing the second signal, there is a risk of erasing the signal written the first time.
Japanese Patent Laid-Open No. 10-040544 (page 4-6, FIG. 1 to FIG. 4) JP 2001-243733 A (page 6-17, FIG. 1 to FIG. 19) Japanese Patent Laying-Open No. 2001-312808 (page 10-12, FIG. 1 to FIG. 3)

in this way,
1. In the current magnetic transfer pattern, the pattern pitch cannot be made fine due to the problem of manufacturing the master disk. For this reason, the pattern by magnetic transfer must be used only as a temporary servo tracking pattern.

  2. That is, since the current magnetic transfer pattern cannot be made fine in the pattern pitch, it is determined that the positioning control of the read head and the write head by the burst pattern cannot be performed as in the case of the conventional servo tracking writer, and the phase A control pattern is used.

  However, this phase control is greatly affected by noise at the current pattern length, and when the recording density of the magnetic recording apparatus increases in the future and becomes high TPI, there is a problem in the head positioning accuracy.

  3. Further, since the current magnetic transfer pattern cannot be made fine as described above, its length is about five times longer than the servo tracking pattern of a normal magnetic recording apparatus. Therefore, it is necessary to use this pattern as a temporary servo tracking pattern and write the final servo tracking pattern by self-servo writing, that is, the servo system of the completed hard disk drive itself.

  However, when calculated from the length of the servo pattern by magnetic transfer, the length of the final pattern, and the circumferential length of the media, the limit of the number of servo tracking patterns per media circumference written on the media is about 350 (2.5 inches, 5400 rpm). And it becomes a value that is not so big. In the future, when TPI increases and 350 or more servo tracking patterns are required per medium, the magnetic transfer pattern cannot be written.

The present invention has been made to solve the above-described problems of the conventional device, and provides a servo tracking pattern recording apparatus capable of recording a servo tracking pattern even when the recording density is increased in the future. It is aimed.

A servo tracking pattern recording apparatus according to a first aspect of the present invention includes a write head and a read head that are provided close to each other, and the write head and the read head that are supported at one end thereof, and can freely rotate on a magnetic disk. A servo tracking pattern recording apparatus for writing a tracking pattern on a magnetic disk of a magnetic recording apparatus having a moving actuator, the permanent magnet having a length capable of covering from the inner periphery to the outer periphery of the magnetic disk; and a yoke attached to the permanent magnet, the gap of the yoke, the write head and read head on an arcuate path and the magnetic disk when moving to the outer periphery from the inner periphery on the magnetic disk Arc tangent and track tangent, which is the trajectory when moving the head at the intersection with each track And magnetic transfer head shape is to be determined as the tangent of the gap is formed an angle of approximately bisecting the angles at the respective intersections of the particular magnetic transfer to be transferred onto the magnetic disk A servo disk comprising a first pattern corresponding to a digital signal composed of a plurality of information and a second pattern corresponding to a plurality of burst signals. The magnetic body portion of the burst signal representing the second pattern is a parallelogram, and the two sides of the parallelogram are straight lines approximating a circular arc parallel to the circumferential track direction. The remaining two sides are linear approximations of the arc when the write head and read head move between the inner and outer peripheral parts on the magnetic disk. And is characterized in that consists of parallel straight lines were.

According to the servo tracking pattern recording apparatus of the first aspect of the present invention, the write head and the read head provided close to each other, and the write head and the read head are supported at one end thereof, so that the magnetic disk can be freely moved. A servo tracking pattern recording apparatus for writing a tracking pattern on a magnetic disk of a magnetic recording apparatus having a rotating actuator, and a permanent magnet having a length capable of covering the inner periphery to the outer periphery of the magnetic disk when, and a yoke attached to the permanent magnet, the gap of the yoke, arc-shaped trajectory and magnetic when the write head and the read head moves from the inner periphery on the magnetic disk to the outer peripheral portion Arc tangent and track, which is the trajectory when moving the head at the intersection with each track on the disk And magnetic transfer head shape is to be determined as the tangent and the angle of each approximately bisecting the angle the tangent of the gap in the respective intersections of is formed, certain to be transferred onto the magnetic disk A master disk on which a magnetic transfer pattern is formed, and the magnetic transfer pattern includes a first pattern corresponding to a digital signal including a plurality of pieces of information and a second pattern corresponding to a plurality of burst signals. It is a servo tracking pattern, and the magnetic part of the burst signal representing the second pattern is a parallelogram, and the two sides of the parallelogram are straight lines approximating a circular arc parallel to the circumferential track direction. The remaining two sides straighten the arc when the write head and read head move between the inner and outer peripheral parts on the magnetic disk. Since it was set to be a parallel straight line that approximates, usually it is possible to transfer the pattern to allow the same control as the burst pattern being used for a magnetic recording apparatus, the length of the pattern with can provide accurate servo tracking pattern Therefore, there is an effect that a servo tracking pattern recording apparatus that can increase the number of servo tracking patterns transferred to one track can be obtained.

(Embodiment 1)
In the first embodiment, the digital part and the burst signal part are recorded in the circumferential direction, and the burst signal part is magnetically recorded in the radial direction. A magnetic transfer pattern, a writing method thereof, and a signal processing for positioning control of the read / write head that can be recorded on will be described.

Embodiments of the present invention will be described below with reference to the drawings.
First, as shown in FIG. 1, DC erase of media is performed using a head dedicated for DC erase (see step 101 in FIG. 3). Although this operation itself is the same as that of the conventional example shown in FIG. 16, the dedicated head used at that time is different from that of the conventional example.

  That is, as shown in FIG. 4A, this dedicated head is obtained by attaching a yoke 18 to a permanent magnet 19, but at any intersection with any track tr1 (,..., Trn) on the gap 18a. The arc is such that the angle (about 45 °) formed by dividing the angle (about 90 °) between the track tangent t1 and the arc tangent n1 which is the trajectory when the head moves is the tangent t2 of the gap 18a. The shape has been determined. Such a gap shape makes it possible to apply a magnetic field to each track so as to form an angle of about 45 °. Instead of this head, a head as shown in FIG. 5 may be used.

Then, this magnetic transfer head is fixed at the position shown in FIG. 4A, and one of the magnet 19 and the medium 7 is rotated one or more times around the media center. The direction of rotation may be left or right. At this time, the distance between the magnet 19 and the medium 7 is 0.5 mm to 2 mm, and a signal actually transferred is confirmed and determined by its characteristics. This distance depends on the holding force of the media, the strength of the magnet, the shape of the pattern, and the like.
The direction of the magnetic field applied to the medium is determined by the mounting direction of the permanent magnet and the shape of the yoke.

  The present invention is characterized in that the pattern of the digital portion of the servo tracking pattern is simultaneously written in the circumferential direction of the medium when the magnetic recording apparatus is completed, and the burst pattern portion is simultaneously written in the radial direction. Therefore, as shown in FIG. 4A or FIG. 5, the direction of the permanent magnet is the ideal direction in the direction in which the digital part pattern is magnetized and the direction in which the burst pattern is magnetized. It is desirable to set it in the middle of the ideal orientation.

  Next, the master disk is brought into contact with the medium to apply a magnetic field to the magnetic recording layer of the medium. Here, the master disk will be described.

  As shown in FIG. 2, the master disk 3 forms a pattern to be transferred by the magnetic body 3a on the non-magnetic substrate 3b (see step 102).

  The burst signal part of the magnetic part is a parallelogram, and its two sides consist of two straight lines approximating a circular arc parallel to the circumferential track direction, and the remaining two sides are the head from the inner circumference to the outer circumference. It consists of two parallel straight lines approximating a circular arc when moving to the center, and each burst signal pattern is formed with an interval greater than that required in the master disk manufacturing process.

  More specifically, the shape of the magnetic material forming the burst signal pattern is such that the radial direction is longer than the minimum pattern that can be manufactured in the master disk manufacturing process, and the circumferential direction is a burst signal at the inner periphery of the magnetic disk. Has a length proportional to the radius in the burst signal on the outer periphery of the magnetic disk, and the interval between adjacent burst signal patterns is more than the minimum interval that can be manufactured in the master disk manufacturing process in the radial direction. The length and circumferential direction of the burst signal at the inner periphery of the magnetic disk have a length that is greater than the minimum interval that can be manufactured in the master disk manufacturing process, and the burst signal at the outer periphery of the magnetic disk has a length that is proportional to the radius. However, n types (n is an integer of 2 or more) burst signals are arranged so as to be shifted from each other at an interval of 1 / n of the pitch of the magnetic material in the radial direction. It is way. Therefore, an accurate servo tracking pattern can be obtained by magnetic transfer, the length of the magnetic transfer pattern can be shortened, and the number of servo tracking patterns transferred to one track can be increased. It is a master disk.

  As the magnetic transfer pattern of the master disk 3, a pattern for phase control is used in the conventional magnetic transfer, and there are two kinds of oblique magnetic patterns in opposite directions as shown in FIG. And a normal pattern that is linear in the radial direction instead of the diagonal direction. Each pattern is required to have a length of 20 bits or 30 bits in order to reduce the influence of noise. Further, the width of the magnetic body and the width of the non-magnetic body portion must be 0.5 μm or more in the current master disk manufacturing process. Therefore, the length of the pattern of the phase control unit in the media circumferential direction is (20 to 30 bits) × 2 × 3 × 0.5 μm = 60 to 90 μm at the narrowest pattern width of the innermost media. The pattern width at the outer periphery of the media was increased in proportion to the radius.

  On the other hand, the pattern for magnetic transfer in the master disk of the present invention is not for phase control, and there is no oblique pattern in order to correspond to writing by a burst control method, which was performed by a conventional servo track writer. As shown in FIGS. 6A and 6B, there are eight burst patterns A, B, C, D, E, F, G, and H. The numerical value of 8 is determined from the shift pitch of each burst pattern, and if the shift pitch is changed, it can be a number other than 8. In FIG. 6, the burst patterns A, B, C, D, E, F, G, and H are separated from each other and slightly shifted in the circumferential direction (see FIG. 6A) and are adjacent to each other. Burst patterns A, B, C, D, E, F, G, and H are connected to each other, and peak noise generated when magnetic transfer is performed on the side of the parallelogram of the burst signal in the radial direction of the media is reduced. Two types of patterns are shown, one that can be used (see FIG. 6B), and any of them may be used. The width of the media in the radial direction of the magnetic body and the non-magnetic body is 0.5 μm, and the length in the circumferential direction is the length of the conventional burst pattern in the innermost servo signal of the media. The total length is 5 μm × 8 = 40 μm, which is 30 to 50% shorter than the conventional pattern. Each burst pattern from A to H is shifted in the radial direction by a length of 1/8 of the pitch of the magnetic material. There is no need to be particular about the order of the eight burst patterns from A to H. In addition, the radial width of the magnetic body and the non-magnetic body portion need not be limited to 0.5 μm. If a pattern of 0.5 μm or less can be created in the future, the spacing that can be created at that time can be used. Conversely, patterns of 0.5 μm or more can also be used. At that time, adjustment is performed by reducing or increasing the number of burst patterns. The ratio of the length in the radial direction between the magnetic body (N) and the non-magnetic body part (S) may not be 1: 1, and (NS) / (N + S) is within ± 40%. If it is within this range, the positioning control of the read head and the write head is possible. This ratio is not an absolute pattern width of each pattern, but is based on signal measurement after actual transfer. This ratio is called signal asymmetry.

  Next, the master disk is brought into contact with the medium (see step 103), and magnetic transfer is performed, but this is not limited to the same size as the medium. The medium may be a so-called aluminum disk or glass disk using aluminum or glass as a nonmagnetic substrate. Thereafter, a magnetic field is applied from the back side of the master disk using a yoke and permanent magnet having the same shape as that used for erasing the medium (see step 104). That is, there are two types of head shapes, FIG. 4A and FIG. 5, both of which are half the angle (about 90 °) formed by the tangent line of the arc, which is the locus when the head moves, and the tangent line of the track. A gap is formed so as to intersect each track, whereby a magnetic field is applied to the track at an angle of about 45 °. One of the heads shown in FIGS. 4A and 5 selected at the time of erasing is also used at the time of magnetic transfer. The magnetic field is applied by rotating the media or permanent magnet one or more times in the same manner as in erasing. However, the direction of the magnetic field at that time is opposite to that during erasing. The direction of the magnetic field is preferably 180 degrees opposite to that during erasing. The distance between the permanent magnet and the back surface of the master disk is 0.5 mm to 3 mm. The transfer is actually performed, and the distance is determined by checking the media signal at that time.

  The medium thus created is incorporated to complete the hard disk drive (see step 105).

  A hard disk drive is a rotor in which one or a plurality of media for magnetic recording, a motor for rotating the media, a write head for reading / writing data and a read head are provided in proximity to each other. An arm, a driving device for driving the rotor arm, a circuit for writing a signal, and a circuit for reading the signal; At least one magnetically transferred medium is incorporated in the magnetic recording apparatus according to the specifications of the apparatus. One side of the media that is magnetically transferred is sufficient. After the assembly, the head is positioned by the signal magnetically transferred in the test process of the magnetic recording apparatus, and the cell flight of the final servo tracking signal is performed. That is, the final servo tracking signal is written on the entire surface of the medium by all the heads of the magnetic recording apparatus itself (see step 106).

A method for performing head positioning control using the magnetic transfer signal will be described below.
The pattern of the master disk of the present invention is as shown in FIG. 6, and the signal transferred to the medium of the burst signal portion A surrounded by the square Q in FIG. 6 (a) is 3 as shown in FIGS. Represented by a dimensional graph. In this graph, the vertical axis represents the voltage when read by the head. FIG. 7 shows a signal to be transferred when the pattern of the present invention is subjected to DC erase and magnetic transfer at the attachment position of the conventional magnet and yoke.

  FIG. 8 is a three-dimensional graph showing signals when a magnetic field is applied to the pattern of the present invention by applying a magnetic field at a predetermined angle with respect to the circumferential direction using the magnet and yoke of the present invention. . In FIG. 7, no signal is generated in the portion corresponding to two sides parallel to the circumferential direction of the parallelogram (rectangular) portion formed of the magnetic material of each burst signal, but in FIG. Signals X1 and X2 are generated. Similarly to FIG. 7, radial signals Y1 and Y2 are also generated, and the signal peaks L1 and L2 are substantially L-shaped. In the present invention, signals X1 and X2 in the circumferential direction are read to position the head. Using a window for each burst, the first and last noisy portions of the burst signal that are expected to be noisy are removed, the signal is captured, and signal processing is performed.

  A burst signal written by a conventional servo track writer is written by a head of a magnetic recording apparatus or a head equivalent to this head at a frequency of several tens of MHz as shown in FIG. Therefore, the direction of the magnetic field to be recorded is inevitably the circumferential direction, and the signal read by the head is an isolated waveform as shown in FIG. 9 or a continuous isolated waveform such as a sine waveform. The position of the head in the radial direction can be read by reading the peak voltage value of the waveform. This waveform is one isolated waveform for one burst signal (one set on the plus side minus one side). Reading the peak voltage of the burst signal provides sufficient reliability due to the influence of electrical noise. Absent. Therefore, the influence of the noise component is reduced by writing a plurality of isolated waveforms. Also, it is desirable to shorten the servo pattern and burst signal as much as possible because they compress the data area. However, there is a limit to reducing the number of continuous isolated waveforms for the reasons described above. Therefore, it is conceivable to increase the write frequency and shorten the total length of the signal. However, when the frequency is increased, the isolated waveforms interfere with each other, the voltage at the time of reading the written signal decreases, the influence of noise increases, and the head positioning accuracy deteriorates. For the above reason, the burst signal is a repetition signal of about 10 to 20, and its frequency is determined to be several tens of MHz. Therefore, in order to reproduce the signal in the conventional burst signal and create the positioning signal for the head, a complicated method for obtaining the maximum voltage value of the signal of several tens of MHz is required.

  In contrast, in the present invention, the direction of magnetic recording is not limited to the circumferential direction, the digital signal portion is circumferentially transferred, and the analog signal portion burst signal is radially transferred to the intermediate direction. Is taking the angle. Therefore, when the pattern according to the first embodiment is magnetically transferred by the magnetic transfer head according to the first embodiment, there are components magnetized in the circumferential direction and the radial direction, and both of them can be read out. .

  Since the conventional burst signal is written using the head of the magnetic recording apparatus, it can only be recorded in the circumferential direction. When the recorded signal is read, it has an isolated waveform shape. The position of the head is recognized by the voltage value of this signal. However, since information of only one set is greatly affected by noise and cannot accurately position the head, a plurality of isolated waveforms are written in the form of a sine wave signal. To improve the accuracy of the signal.

  Since the present invention can record a signal by applying a magnetic field of a radial component, when the head moves in the circumferential direction and reads the signal, it appears as a voltage value of a DC component rather than an isolated waveform. Therefore, the signal is not written with a constant frequency signal as is written in a conventional burst signal. For this reason, a complicated method for obtaining a peak voltage of a signal having a constant frequency after reading is not required.

  FIG. 10 is a graph showing the read voltage value of each burst of the present invention for each head position in the radial direction. The width of the magnetic material forming the burst is 0.5 μm, the interval between the magnetic materials is 0.5 μm, the number of burst signals is 8, and the names of the burst signals are A, B, C, D, E, F, G, H. The radial deviation of the burst signals adjacent to the eight magnetic bodies forming each burst signal is 1/8 with respect to the pitch of the magnetic bodies, and the deviation directions are all the same direction (A burst). Thus, it is assumed that the B burst is shifted to 1/8 (1/8 μm) of the pitch of the magnetic material on the inner circumference side of the medium, and C, D, E, F, G, and H are respectively on the digital signal side of the burst signal. It is shifted to the inner diameter side of the media by 1/8 of the magnetic pitch with respect to the burst signal. These numerical values are merely representative values for explanation, and the present invention is not limited to the specified number of bursts, shift amount (pitch), magnetic body width, and magnetic body interval. Each burst signal waveform shown in the graph is similar to an isolated waveform, and the rising and falling parts of the signal are not straight lines, and the amount of head movement in the radial direction and the output value of the head It can be understood that is not proportional. FIG. 11 shows a waveform in which 40% of signal asymmetry occurs. With this signal, it is considered difficult to control the head positioning sufficiently accurately with respect to the self-servo write.

  However, if the sum of several voltage values of these eight burst signals is taken as the value of one burst signal, the rising and falling portions of the signal are linear, and the signal of this linear signal These problems are solved by positioning the head using the rising and falling portions.

  FIG. 12 shows the waveform of a signal obtained by adding the values of a total of three burst signals, one burst signal and burst signals adjacent to both. In FIG. 12, A + B + C is B ′, B + C + D is C ′, C + D + E is D ′,..., G + H + A is H ′, and H + A + B is A ′. The number of burst signals obtained by adding these three burst signals is eight, which is the same as the number of original burst signals. This signal is a signal with 0% signal asymmetry.

  Next, when the difference between A ′ and E ′ where the voltage values are opposite to each other, that is, the waveforms of A′−E ′, B′−F ′, C′−G ′, and D′−H ′ are confirmed. As shown in FIG. 13, both rising and falling are linear, and represent a very good waveform (value) for head positioning control.

  FIG. 14 shows waveforms of A′-E ′, B′-F ′, C′-G ′, and D′-H ′ when the signal asymmetry becomes 40%. Also in this case, the signal asymmetry is not affected at all, the rising and falling slopes are symmetric, and the respective slopes are substantially linear. Further, since there are many overlapping portions of the rising straight portions of the four waveforms, it can be known that there is a margin with respect to the head positioning control. If there is no margin in this overlapping portion, the amount of deviation of the burst signal can be reduced, and the margin can be ensured by increasing the number of burst signals. At this time, increasing the number of burst signals added is one of the possibilities for increasing the margin.

The waveforms in these graphs are simulations with a read head width of 0.1 μm. However, even if the head width is 0.02 μm, this straight portion can be sufficiently secured. Therefore, it can be judged that this burst signal may be used up to about 6 × 10 ⁵ TPI or more.

  Further, according to this signal processing method, the voltage of the signal read by the read head is considered to be lower than the output signal of the conventional transfer method. This is because the direction of the magnetic field at the time of erasing and the direction of the magnetic field at the time of transfer are not about the track direction but about 45 degrees with respect to the track direction. Even in the conventional phase control pattern, the oblique pattern portion of the phase control is about 45 degrees on the outer periphery of the medium, and the output is slightly lower than that of the non-oblique pattern by 10%. Therefore, the signal voltage is estimated to be about 80% to 90% compared to the normal transfer signal. However, it can be determined that such a decrease in the signal voltage has no problem with the head positioning.

  Further, according to this signal processing method, the absolute position of the head can be corrected even when signal asymmetry occurs. That is, signal asymmetry occurs when the width of the magnetic material is widened or narrowed in the process of creating the master disk, or when a fine gap is generated between the master disk and the medium during magnetic transfer. . However, in any of these cases, the position of the portion corresponding to the central portion of the magnetic body and the portion corresponding to the center of the non-magnetic portion of the read signal does not change. That is, according to this signal processing method, for example, FIG. 13 showing a control signal in which no signal asymmetry is generated, and FIG. 14 showing a control signal in which 40% of signal asymmetry is generated, The intersection of is the same. Therefore, it can be seen that the signal asymmetry can be corrected almost completely.

  FIG. 15 shows a head positioning control circuit for adding and subtracting such a plurality of waveforms to generate a signal having linearity at the rising or falling part, and signal-processing this to position the head. An example of a part of the configuration is shown.

A magnetic transfer pattern corresponding to the tracking pattern magnetically transferred to the medium is read by the read head 14a, and the head amplifier 151 amplifies the read signal. The sample value acquisition circuit 152 acquires a sample value from the read signal, and the signal continuity detection circuit 154 outputs, for example, eight types of signals shown in the graph showing the relationship between the head position and the burst signal voltage shown in FIG. By determining the continuity of the signal, it is determined particularly at the point where the signals intersect. The signal separation circuit 153 separates the output signal of the sample value acquisition circuit 152 into eight types of signals A, B, C, D, E, F, G, and H based on the determination result. The adder circuits 155 to 162 have three adjacent signals A, B, C among these eight kinds of signals A, B, C, D, E, F, G, H.
B, C, D
C, D, E
………
G, H, A
H, A, B
Add each for
B ′ (= A + B + C)
C ′ (= B + C + D)
D ′ (= C + D + E)
………
H ′ (= G + H + A)
A ′ (= H + A + B)
Get.
The subtraction circuits 163 to 166 have C′−G ′.
D'-H '
A'-E '
B'-F '
When the eight types of signals A ′ to H ′ described above are used, these subtracting circuits are not necessary.

  The window setting circuit 170 obtains eight types of signals A ′ to H ′ (or four types A′−E, B′−F ′, C′−G ′, and D′−H ′) thus obtained. The signal processing circuit 171 uses the signal at the rising or falling portion to track the read head 14a using the signal at the rising or falling portion. Perform signal processing. At this time, since the extracted signal is linear, the signal processing circuit 171 can easily perform accurate head positioning control.

Thus, according to the first embodiment,
1. An accurate burst pattern can be provided. It can be used even if the TPI increases.
2. In order to increase the positioning accuracy of the read head and the write head, it is not necessary to reduce the interval between the magnetic body portion and the non-magnetic body portion, and there is no problem of signal asymmetry.
3. Since the length of the servo tracking pattern can be shortened, it can be used even if the number of servo tracking patterns in the magnetic recording apparatus is increased. That is, the number of magnetic recording devices with a 2.5 inch diameter medium can be increased from 350 in the current method to 450 in the first embodiment.
4). This magnetic transfer pattern can be used as the final servo tracking pattern. Alternatively, only the burst signal portion can be used as the final burst pattern. In that case, only the digital part is rewritten.
5. The conventional burst signal is written at a constant frequency, and a method for obtaining the maximum value of the signal is required. However, in the first embodiment, the read value of the burst signal appears as a direct current component, so that it is complicated. No technique is required.

  In the first embodiment, the gap shape of the magnetic transfer head is set such that the arc tangent and the track tangent are trajectories when the head moves at the intersections of the trajectories of the read head and write head and the tracks of the magnetic disk. The angle is about 45 °, which is half of the angle formed by the above. However, the optimum value varies depending on the offset angle (skew angle) between the track and the head, and is represented by (90 ° + skew angle) / 2.

  In the first embodiment, the hard disk drive has been described as an example of the magnetic recording device. However, this may be applied to various magnetic disk devices, for example, a large-capacity flexible disk device and a removable disk device. .

  Furthermore, although the hard disk drive has been described as having both a read head and a write head in the first embodiment, the present invention may be applied to one having only a read head.

  Further, in the first embodiment, eight types of burst signals are used, and the bits are shifted by 1/8, but the burst signals may be two or more types (= n), and the pitch may be changed. May be shifted by 1 / n.

  In the first embodiment, the case where the DC erase in step 101 of FIG. 3 is executed prior to the creation of the master disk in step 102 has been described, but these steps may be executed simultaneously. Step 102 may be executed prior to Step 101.

  Further, in the first embodiment, the magnetic transfer is performed using the magnetic transfer head that covers the entire radial direction of the medium as shown in FIG. 4A, but as shown in FIG. 4B. It is also possible to use a small magnetic transfer head 200 in which the gap 180a is linear and covers only a part of the medium in the radial direction. In this case, the magnetic transfer head is connected to the outer peripheral portion and the inner peripheral portion of the medium 7. It is only necessary to move so as to draw an arc having the same shape as the head gap shown in FIG. As a result, when the length of the rotor arm of the hard disk drive is changed, or when the distance between the motor center and the pivot center of the rotor arm is changed, the magnetic recording yoke or mounting position is changed or newly created. There is no need to do so and it becomes economical. In FIG. 4B, 180 is a yoke and 190 is a magnet. Further, when the magnetic transfer head shown in FIG. 4B is used, not only is it moved so as to draw a convex arc on the right as shown in FIG. 4B, but also a convex arc is drawn on the left. It may be moved. Further, at the time of DC erasing of the medium and at the time of magnetic transfer, it is only necessary to move the magnetic transfer head having the same shape as in FIG. 4B along the same locus and to reverse only the magnetic field direction.

  In the first embodiment, only the case of horizontal magnetic recording has been described. However, the present invention can also be applied to perpendicular magnetic recording, and the same effect can be obtained.

As described above, the servo tracking pattern recording apparatus of the present invention can position the head with high accuracy and can transfer a tracking pattern in which the length of the transfer signal in the circumferential direction is shortened. It is suitable for use in improving the recording density of the recording apparatus.

It is a figure which shows the mode of the DC erase of the medium in the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows the mode of the magnetic transfer of the medium in the magnetic transfer method by Embodiment 1 of this invention. It is a flowchart figure which shows a series of processes in the manufacturing method of the hard-disk drive using the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows an example of the structure of the head for magnetic transfer of the servo tracking pattern recording device used for the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows another example of the structure of the head for magnetic transfer used for the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows another example of the structure of the head for magnetic transfer used for the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows an example of the disk pattern of the master disk used for the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows the other example of the disk pattern of the master disk used for the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows a signal when the disk pattern of the master disk used for the magnetic transfer method by Embodiment 1 of this invention is transcribe | transferred with the conventional magnetic transfer head. It is a figure which shows the signal when the disk pattern of the master disk used for the magnetic transfer method by Embodiment 1 of this invention is transcribe | transferred with the magnetic transfer head of this invention. It is a figure which shows the burst signal recorded on the medium by the conventional servo track writer. It is a figure which shows the reading voltage of a burst signal. It is a figure which shows the reading voltage of a burst signal whose signal asymmetry is 40%. It is a figure which shows the reading voltage at the time of taking the sum of three burst signals. It is a figure which shows the reading voltage at the time of taking the difference of the sum of three burst signals. It is a figure which shows the reading voltage at the time of taking the difference of the sum of three burst signals whose signal asymmetry is 40%. It is a figure which shows the structural example of a part of head positioning control circuit which positions a head with respect to the medium magnetically transferred by the magnetic transfer method by Embodiment 1 of this invention. It is a figure which shows the mode of the DC erase of the medium in the conventional magnetic transfer method. It is a figure which shows the mode of the magnetic transfer of the medium in the conventional magnetic transfer method. It is a flowchart figure which shows a series of processes in the manufacturing method of the hard disk drive using the conventional magnetic transfer method. It is a figure which shows the example of the structure of the head for magnetic transfer used for the conventional magnetic transfer method. It is a figure which shows the servo signal recorded on the medium of a hard-disk drive. It is a figure which shows schematic structure of a hard disk drive. It is a figure which shows the signal obtained with the head from the magnetically transferred medium. It is a figure which shows the example of the servo tracking pattern of the master disk used for the conventional magnetic transfer method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Media 1a Magnetic layer of media 1b Media body 2 Arrow indicating the direction of the external magnetic field 3 Master disk 3a Magnetic material of the master disk 3b Non-magnetic substrate 4 Arrow indicating the direction of the external magnetic field during magnetic transfer 12 Pivot center of the rotor arm 13 Rotor arm 14 Head 8, 18, 180 Yoke 8a, 18a, 180a Gap 9, 19, 190 Permanent magnet 10, 20, 200 Magnetic transfer head 101, 201 Step of performing DC erase 102, 202 Step of creating master disk 103, 203 Superimposing media and master disk 104, 204 Performing magnetic transfer 105, 205 Assembling hard disk drive 106, 206 Performing self-servo write L1, L2 L-shaped peak tr , ..., arc tangent of the locus at the time of movement of the tangent n1 head tangent t2 head gap trn track t1 track

Claims (1)

A write head and a read head provided close to each other;
A servo tracking pattern recording apparatus for writing a tracking pattern on a magnetic disk of a magnetic recording apparatus having an actuator that is supported by one end of the write head and the read head and that freely rotates on the magnetic disk,
A permanent magnet of a length that can cover the inner periphery to the outer periphery of the magnetic disk;
And a yoke attached to said permanent magnet,
Gap of the yoke, the write head and the read head during movement of the head in the intersection of the tracks on the arc-shaped locus and the magnetic disk when moving to the outer periphery from the inner periphery on the magnetic disk A magnetic transfer head having a shape determined such that a tangent of a gap at each intersection is formed at an angle obtained by dividing an angle formed by a tangent of a circular arc that is a locus and a tangent of a track, respectively.
A master disk on which a specific magnetic transfer pattern to be transferred onto the magnetic disk is formed,
The magnetic transfer pattern is a servo tracking pattern consisting of a first pattern corresponding to a digital signal consisting of a plurality of information and a second pattern corresponding to a plurality of burst signals,
The magnetic part of the burst signal representing the second pattern is a parallelogram, and the two sides of the parallelogram consist of straight lines approximating an arc parallel to the circumferential track direction, and the remaining 2 The side is composed of a parallel straight line approximating a circular arc when the write head and the read head move between the inner peripheral portion and the outer peripheral portion on the magnetic disk.
A servo tracking pattern recording apparatus .

Images