JP2008234727A - Writing method of servo tracking pattern, photomask, thermomagnetic transfer apparatus, and magnetic disk - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for forming a servo tracking pattern on a magnetic disk by thermomagnetic transfer even when recording density is improved. <P>SOLUTION: Eight kinds of burst signal patterns respectively deviated by 1/8 pitch in a radial direction are formed previously on a photomask 20. The photomask 20 and a medium 1 are positioned with spacings. A magnetic field is applied in a direction of about 45° with respect to a track by permanent magnets 21a, 21b, 21c and 21d and a coil 22. An energy-beam generator 24 irradiates an energy-beam irradiation area A1 between the permanent magnets 21a and 21b with an energy beam. This makes it possible to conduct thermomagnetic transfer of burst signal patterns having components in both of the radial direction and a track direction to the reproduction signal. By positioning a read head on the basis of the burst signals, the size of the servo tracking pattern can be reduced, and positioning of a head can be controlled even when the read head becomes not larger than 0.1 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a servo tracking pattern writing method, a photomask, a thermomagnetic transfer apparatus, and a magnetic disk for writing a servo tracking pattern on a magnetic recording medium (hereinafter referred to as a medium) driven in a magnetic recording apparatus. The present invention relates to an improvement in a magnetic transfer pattern in a magnetic transfer system, a method for writing the pattern, and a method for positioning a head from a read signal of a magnetic transfer pattern written on a medium. The present invention also relates to the one that enables the length of the transfer signal in the circumferential direction to be shortened.

  When a servo tracking pattern such as a burst signal, an address information signal, and a reproduction clock signal is written (preformat) on a magnetic disk medium (hereinafter referred to as a medium) driven in a magnetic recording device such as a hard disk drive, magnetic transfer technology is used. used.

  In the magnetic transfer technique, a master disk on which the same information as the servo tracking pattern to be recorded on the medium is previously brought into contact with the medium to be preformatted and the content is transferred to the medium by applying a magnetic field. Then, this media is incorporated into the magnetic recording device, and self-servo writing (writing using the servo system of the magnetic recording device itself) is performed based on the preformat recorded signal during the self-test of the magnetic recording device. Write the final servo tracking pattern.

  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.

  In FIG. 16, 1 is a medium composed of a media body 1b and a magnetic layer 1a formed on the surface (one main surface), 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, and the magnetization direction of the magnetic layer 1a is aligned in the same direction as the arrow 2 (see step 201 in FIG. 18).

  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 rotation direction may be either left rotation or right rotation. 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 has actually been 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. 23, and the striped portion 3a in FIG. 17 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 (the main surface on the side where the magnetic body 3a is formed) and the main surface on the side where the magnetic layer of the medium 1 is formed are brought into contact with each other as shown in FIG. 203), using a head 10 (see FIG. 19) having the same shape as that used in the DC erase, a magnetic field is applied in the 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 servo signals 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 has one or more media for magnetic recording, a motor for rotating the media, and a rotor having one or more read heads and write heads for reading and writing data on the media. An arm, a driving device for driving the rotor arm, a circuit for writing a signal to the write head, and a circuit for reading the signal from the read head; At least one magnetically transferred medium is incorporated into the magnetic recording device according to the specifications (capacity) of the hard disk drive (see step 205).

  FIG. 21 is a schematic diagram showing a state in which the cover of the completed hard disk drive is opened, from the read and write heads provided in the vicinity of each other for reading and writing data to and from the recording disk (medium) 1. The head 14 is installed by the rotor arm 13 so as to be rotatable within a predetermined range with respect to the pivot center 12 within the inner and outer circumferences of the medium 1.

  FIG. 22 shows a signal obtained by reading the magnetized pattern with a reproducing 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 distance between the magnetic parts in the production process. Therefore, the frequency of the pattern is When the tracking pattern is recorded by the magnetic head of the servo track writer, it becomes about 1/5 with respect to the frequency of the servo tracking pattern of the magnetic recording apparatus.

  Therefore, when the magnetization pattern formed by this magnetic transfer method is used as the final pattern of the magnetic recording apparatus, the occupation ratio in the data area is increased, so that it is used only to form a temporary servo tracking pattern on the medium. .

  Further, since the master disk is wide in both the magnetic part and the non-magnetic part, the burst signal used in the magnetic recording apparatus cannot be used. For this reason, the phase shown in FIG. 23 is used instead of the burst signal. A control signal is used.

  As shown in FIG. 23, this phase signal is composed of three types of patterns called Zig (P1), Zag (P2), and Preamble (P3) and a digital signal (P4), each having 20 to 30 bits (magnetic part, The length of 20 to 30 non-magnetic parts is required, and 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).

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

  As described above, Patent Document 2 (“Disk”) describes a method in which a phase control signal is used as a temporary signal and a self-servo write, that is, a magnetic recording apparatus itself records a servo tracking pattern on its own media using its own servo system. Drive self-servo writing method and embedded reference pattern used therefor ”).

  As another magnetic transfer method, there is a method of performing magnetic transfer by applying heat and magnetism to a medium as shown in FIGS. This method is performed by the thermomagnetic transfer apparatus shown in FIGS. As shown in FIG. 25, the thermomagnetic transfer apparatus 250 is parallel to each other at positions symmetrical to the radial direction below the main surface on the lower side of the medium 1 and the upper main surface of the photomask 20 that are positioned relative to each other. The hexagonal region 3 includes two pairs of rod-like permanent magnets 210a, 210b and 210c, 210d arranged with their polarities (N, S) reversed to each other and surrounded by two pairs of upper and lower permanent magnets. It has a coil 220 formed by winding a wire at a position corresponding to one side surface, and is further sandwiched between a power source that generates a pulse magnetic field by energizing the coil 220 and the permanent magnets 210a and 210b. An energy beam generator 240 for irradiating the energy beam irradiation area A0 on the photomask 20 with an energy beam.

  In this thermomagnetic transfer method, the medium 1 is DC erased in the same manner as the magnetic transfer method, and the photomask 20 on which the pattern for transferring the magnetized pattern is formed is brought into contact with the medium 1 or an interval of several μm or less. As shown in FIG. 25, they are positioned symmetrically with respect to the radius above the upper main surface of the photomask 20 and below the lower main surface of the media 1 as shown in FIG. Two pairs of rod-like permanent magnets 210a, 210b and 210c, 210d arranged in parallel with each other and reversed in polarity (N, S) are arranged, and an energy beam irradiation area A0 sandwiched between the permanent magnets 210a, 210b is arranged. An energy beam from an energy beam generator 240 such as a surface emitting laser is irradiated, and the energy beam is irradiated simultaneously with the irradiation of the energy beam. The by 230 and the coil 220 was applied a magnetic field during the erase apply a magnetic field in the opposite direction. As a result, since the temperature of the place irradiated with the energy rays rises, the coercive force decreases and magnetization reversal occurs. This method is characterized in that magnetic transfer can be performed without bringing a photomask into contact with the medium.

  However, phase control by such magnetic transfer (including thermomagnetic transfer) is greatly affected by electrical noise, and when the magnetic recording apparatus has a high TPI, the current phase control signal bit length and current signal processing There may be a problem with the control of the head.

  In addition, the phase control pattern using the magnetic transfer method has a long pattern length, so the limit of the number of servo tracking patterns written on the medium is about 350 (in the case of 2.5 inch, 5400 rpm hard disk drive media). This is not a big value.

  By the way, Patent Document 3 (“Magnetic” disk and its magnetic pattern forming method and magnetic disk apparatus) 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, a SAM (Servo Address Mark) signal section for determining that it is a servo tracking signal, and a track number. It is composed of information such as a track number portion representing.

  In addition, the digital signal unit is magnetically recorded in the radial direction of the medium in consideration of the tracking mechanism method of the conventional magnetic recording device, so that it adjusts the reading timing, determines the amplification factor, and servos. 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. Accordingly, since there is a digital signal part that must be recorded in the circumferential direction (track direction), the servo tracking signal must be recorded in the radial direction when the burst signal part is to be magnetically recorded. It is necessary to record. However, these two types of signal writing methods are not disclosed in Patent Document 3.

  As a method of writing such two types of signals, a method of dividing the digital signal portion and the burst signal portion into two master disks and writing these two types of signals by writing twice can be considered. In this case, the alignment of the two signals becomes a problem. The two signals need to have a radial deviation within a few nm, and it is very difficult to do this in a process that is currently in practical use. In addition, when writing a second signal, there is a risk of erasing the first recorded signal.

  As described above, the magnetic transfer pattern of the current magnetic recording apparatus has the following problems.

  1. Since the current magnetic transfer pattern cannot make the pattern pitch fine, it is judged that the head positioning control by the conventional burst pattern cannot be performed, and the phase control pattern is used together. This phase control is greatly affected by noise at the current pattern length, and when the recording density of the magnetic recording apparatus is increased to a high TPI, there is a problem in the head positioning accuracy.

  2. Since the current magnetic transfer pattern cannot have a fine pattern pitch, its length is about five times longer than the servo tracking pattern of a normal magnetic recording apparatus. Therefore, it is necessary to consider writing this pattern as a temporary servo tracking pattern and writing the final pattern by self-servo writing. However, when calculating from the length of the servo pattern by magnetic transfer, the length of the final pattern, and the circumference of the medium, the limit of the number of servo tracking patterns per medium circumference written on the medium is about 350 (2.5 inches, 5400 rpm). )) And not so large. If the TPI increases in the future and the number of servo tracking patterns per medium circumference is 350 or more, it becomes impossible to write the magnetic transfer pattern.

  3. The current magnetic transfer pattern cannot be made finer, so it is used only as a temporary servo tracking pattern. The actual servo tracking pattern is formed after the temporary servo tracking pattern is formed. It is necessary to execute self-servo write separately.

  However, the present inventor has already developed a method capable of solving various problems related to the magnetic transfer pattern of such a magnetic recording apparatus.

That is, this method is disclosed in Patent Document 4 (“servo tracking pattern writing method, servo tracking pattern, master disk, medium, magnetic transfer head, magnetic transfer head moving method, magnetic disk, and head positioning method”). As shown, eight kinds of burst patterns, each of which is shifted by 1/8 pitch in the radial direction, are formed on the master disk by a magnetic material and a non-magnetic material. By applying an exciting magnetic field in the direction of about 45 ° to the track, the magnetic recording is performed twice when the digital portion of the servo tracking signal is recorded in the circumferential direction and the burst signal portion of the servo tracking signal is recorded in the radial direction. Pattern, writing method and head position that can be recorded at once without dividing Signal processing method of the control in which can provide.
JP 10-40544 A JP 2001-243733 A JP 2001-312808 A JP 2005-174429 A

  The method described in Patent Document 4 is a method in which a medium and a master disk are brought into direct contact with each other, and a magnetic material portion absorbs magnetic flux therein to weaken a magnetic field in the vicinity thereof. Since the master disk is brought into direct contact with the master disk, there is a possibility that the medium may be damaged by the master disk, which causes a problem in terms of yield. In addition, since the magnetic flux (magnetic field) is distorted, there is a problem that transfer by a sharp oblique magnetic field cannot be executed.

  The present invention has been made to solve the above-described problems of the prior art, and a servo tracking pattern based on the method of the present applicant, which has solved various problems related to the current magnetic transfer pattern, is applied to a medium. An object of the present invention is to provide a servo tracking pattern writing method, a photomask, a thermomagnetic transfer apparatus, and a magnetic disk that can be transferred with a sharp oblique magnetic field without causing damage.

  In the servo tracking pattern writing method according to claim 1 of the present invention, the write head, the read head, the write head, and the read head, which are provided close to each other, are respectively supported at one end of the write head and the read head on the magnetic disk. In a method for writing a tracking pattern onto a magnetic disk in a magnetic recording apparatus having an actuator that freely rotates, a step of DC erasing the magnetic disk, a photomask substrate transparent to energy rays, and the photomask substrate A mask pattern layer made of a material opaque to the energy beam on one main surface of the material and having a thermomagnetic transfer tracking pattern to be transferred to the magnetic disk formed by the presence or absence of the opaque material. A photomask and the magnetic disk are several μm or less A step of positioning with a gap, and the magnetic disk and the photomask are arranged with a gap of several μm or less in a direction opposite to the direction in which the magnetic field is erased and with respect to the track. Irradiating the energy beam from the photomask side while applying at an angle of about 45 degrees to thermomagnetically transfer the thermomagnetic transfer pattern on the photomask to the magnetic disk. It is what.

  The servo tracking pattern writing method according to claim 2 of the present invention is the servo tracking pattern writing method according to claim 1, wherein the thermomagnetic transfer tracking pattern corresponds to a digital signal corresponding to a plurality of information. 1 is a servo tracking pattern including a second pattern corresponding to a plurality of burst signals, the transparent portion representing the second pattern is a parallelogram, and the two sides are circumferential track directions Is composed of two straight lines approximating a circular arc that is parallel to the arc, and the remaining two sides are straight lines when the write head and the read head move between the inner peripheral portion and the outer peripheral portion on the magnetic disk. It consists of two approximate parallel straight lines, and the first pattern and the second pattern are mutually in the photomask manufacturing process. That are formed with an interval of more than spacing required Te is characterized in.

  According to a third aspect of the present invention, there is provided a photomask according to a third aspect of the present invention, wherein the write head, the read head, the write head, and the read head provided close to each other are supported on one end of the photomask. A photomask for writing a tracking pattern on a magnetic disk in a magnetic recording apparatus having a freely rotating actuator, the photomask being transparent to an energy beam used when the tracking pattern is transferred onto the magnetic disk The substrate and a mask pattern layer formed on one main surface of the photomask substrate are made of a material opaque to the energy rays and formed with a tracking pattern for thermomagnetic transfer to be transferred to the magnetic disk. Furthermore, the tracking pattern for thermomagnetic transfer is based on a plurality of information. A servo tracking pattern comprising a first pattern corresponding to a digital signal and a second pattern corresponding to a plurality of burst signals, wherein the second pattern is a parallelogram, and the two sides are circumferential. The remaining two sides are arcs when the write head and read head move between the inner and outer peripheral parts on the magnetic disk. The first pattern and the second pattern are formed with an interval larger than the interval required in the photomask manufacturing process. is there.

  According to a fourth aspect of the present invention, in the photomask according to the third aspect, the shape and size of the transparent part forming the burst signal pattern can be manufactured in the photomask manufacturing process. The length is longer than the minimum pattern, and the circumferential direction has a length proportional to the radius of the magnetic disk in the burst signal at the outer periphery of the magnetic disk. The interval of the burst signal pattern is longer than the minimum interval that can be manufactured in the photomask manufacturing process in the radial direction, and the minimum interval that can be manufactured in the photomask manufacturing process in the case of the burst signal in the circumferential direction of the magnetic disk The length of the burst signal on the outer periphery of the magnetic disk has a length proportional to the radius, and n types (n is an integer of 2 or more) burst signals. So that it is to be placed offset from one another in the first interval n of the pitch of the transparent portion in the radial direction, and is characterized in that the second pattern is formed.

  The photomask according to claim 5 of the present invention is the photomask according to claim 3, wherein the second pattern has a shape in which burst signal patterns adjacent to each other in the circumferential direction are connected by a transparent portion. Furthermore, it is characterized by having.

  According to a sixth aspect of the present invention, there is provided a thermomagnetic transfer apparatus, wherein the write head, the read head, the write head, and the read head that are provided close to each other are respectively supported at one end of the magnetic disk. A thermomagnetic transfer apparatus for writing a tracking pattern on a magnetic disk in a magnetic recording apparatus having an actuator that freely rotates above, and a plurality of lengths that can cover from the inner periphery to the outer periphery of the magnetic disk Permanent magnets, and the plurality of permanent magnets or yokes are arc-shaped tracks and tracks on the magnetic disk when the write head and the read head move from the inner periphery to the outer periphery on the magnetic disk. The angle formed by the tangent of the arc, which is the trajectory when the head moves, and the tangent of the track at each intersection of It is characterized in that it has a shape as formed so that.

  The thermomagnetic transfer apparatus according to claim 7 of the present invention is the thermomagnetic transfer apparatus according to claim 6, wherein the plurality of permanent magnets are arc-shaped permanent magnets having different curvatures, and the curvatures of the permanent magnets are different from each other. Different arc-shaped permanent magnets are arranged above and below the photomask so that the energy beam irradiation area sandwiched between the permanent magnets is narrow on the inner peripheral side of the photomask and wide on the outer peripheral side. It is characterized by.

  A magnetic disk according to an eighth aspect of the present invention is characterized in that a servo tracking pattern is written by executing the servo tracking pattern writing method according to the first or second aspect.

  The magnetic disk according to claim 9 of the present invention uses the thermomagnetic transfer apparatus according to claim 6 or 7 when executing the servo tracking pattern writing method in the magnetic disk according to claim 8. It is characterized by this.

  According to the servo tracking pattern writing method of the first aspect of the present invention, the write head, the read head, the write head, and the read head, which are provided close to each other, are respectively supported at one end and magnetically In a method of writing a tracking pattern onto a magnetic disk in a magnetic recording apparatus having an actuator that freely rotates on the disk, a step of DC erasing the magnetic disk, a photomask substrate transparent to energy rays, and the photo A mask pattern layer made of a material opaque to the energy beam on one main surface of the mask substrate, and a thermomagnetic transfer tracking pattern to be transferred to the magnetic disk formed by the presence or absence of the opaque material; A photomask and a magnetic disk of several μm A step of positioning at a lower interval, and a track in a direction opposite to the direction in which the magnetic field is erased on the magnetic disk in a state in which the magnetic disk and the photomask are arranged with an interval of several μm or less. Irradiating the energy beam from the photomask side while applying at an angle of about 45 degrees to the photomask, and thermomagnetically transferring the thermomagnetic transfer pattern on the photomask to the magnetic disk. As a result, it is possible to record patterns that enable the same control as the burst pattern normally used in magnetic recording devices, so that the servo tracking pattern can be formed with higher accuracy and only the circumferential component of the media. In addition to transferring the signal, it is possible to transfer the signal to the radial component of the media at the same time. Therefore, the number of servo tracking patterns written on one track can be increased, and a magnetic disk on which this servo tracking pattern is recorded can be obtained with a high yield. is there.

  According to a servo tracking pattern writing method according to claim 2 of the present invention, in the servo tracking pattern writing method according to claim 1, the thermomagnetic transfer tracking pattern corresponds to a digital signal composed of a plurality of pieces of information. A servo tracking pattern comprising a first pattern and a second pattern corresponding to a plurality of burst signals, wherein the transparent portion representing the second pattern is a parallelogram, and the two sides are circumferential. It consists of two straight lines approximating an arc parallel to the track direction, and the remaining two sides are arcs when the write head and read head move between the inner and outer peripheral parts on the magnetic disk. The first pattern and the second pattern are mutually photomask manufacturing steps. Since the pattern is formed with an interval greater than the required interval, it is possible to record a pattern that enables the same control as the burst pattern used in a magnetic recording device. The pattern can be formed with higher accuracy, and the signal can be transferred not only to the circumferential component of the media but also to the radial component of the media at the same time, reducing the length of the pattern. Therefore, it is possible to increase the number of servo tracking patterns written in one track and to obtain a magnetic disk on which the servo tracking patterns are recorded with a high yield.

  According to the photomask of the third aspect of the present invention, the write head, the read head, the write head, and the read head, which are provided close to each other, are supported at one end of each, and the magnetic disk A photomask for writing a tracking pattern on a magnetic disk in a magnetic recording apparatus having an actuator that rotates freely, and is transparent to an energy beam used when the tracking pattern is transferred onto the magnetic disk A mask pattern layer comprising a photomask substrate and a thermomagnetic transfer tracking pattern to be transferred to the magnetic disk made of a material opaque to the energy rays on one main surface of the photomask substrate; And the thermomagnetic transfer tracking pattern comprises a plurality of information. A servo tracking pattern consisting of a first pattern corresponding to a digital signal consisting of and a second pattern corresponding to a plurality of burst signals, the second pattern being a parallelogram, the two sides being a circumference It consists of two straight lines approximating a circular arc parallel to the track direction, and the remaining two sides are when the write head and read head move between the inner and outer peripheral parts on the magnetic disk. Since the first pattern and the second pattern are formed with an interval larger than the interval required in the photomask manufacturing process, it consists of two straight lines approximating an arc. The pattern that enables the same control as the burst pattern used in the magnetic recording device can be recorded, and the servo tracking pattern can be formed with higher accuracy. In addition, the signal can be transferred not only to the circumferential component of the medium but also to the radial component of the medium at the same time, and the pattern length can be shortened. It is possible to increase the number of servo tracking patterns written on the track, and to obtain a photomask capable of obtaining a magnetic disk on which the servo tracking patterns are recorded with a high yield.

  According to a photomask of claim 4 of the present invention, in the photomask according to claim 3, the shape dimension of the transparent portion forming the burst signal pattern is manufactured in the photomask manufacturing process. It has a length longer than the smallest possible pattern, and the circumferential direction has a length proportional to the radius of the magnetic disk in the burst signal at the outer periphery of the magnetic disk. The interval between the burst signal patterns is longer than the minimum interval that can be manufactured in the photomask manufacturing process in the radial direction, and can be manufactured in the photomask manufacturing process when the circumferential direction is a burst signal in the inner periphery of the magnetic disk. The length of the burst signal on the outer periphery of the magnetic disk is longer than the minimum interval. The burst signal has a length proportional to the radius, and n types (n is an integer of 2 or more). Since the second pattern is formed so that the signals are arranged so as to be shifted from each other at an interval of 1 / n of the pitch of the transparent portion in the radial direction, it is usually used for a magnetic recording apparatus. It is possible to record a pattern that enables the same control as the burst pattern that is being performed, and it is possible to form a servo tracking pattern with higher accuracy and not only transfer the signal to the circumferential component of the media but also the radial direction of the media. It is possible to simultaneously transfer signals to the components, and the pattern length can be shortened. Therefore, it is possible to increase the number of servo tracking patterns written in one track, and this servo tracking. There is an effect of obtaining a photomask capable of obtaining a magnetic disk on which a pattern is recorded with a high yield.

  Further, according to the photomask of claim 5 of the present invention, in the photomask according to claim 3, the second pattern is formed by joining the burst signal patterns adjacent to each other in the circumferential direction with a transparent portion. Since it has an additional shape, it is usually possible to record a pattern that enables the same control as the burst pattern used in the magnetic recording device, and the servo tracking pattern can be formed with higher accuracy, and the circle of the media can be formed. Not only can the signal be transferred to the circumferential component, but also the signal can be transferred simultaneously to the radial component of the media, and the pattern length can be shortened. It is possible to increase the number of tracking patterns, and the magnetic disk on which this servo tracking pattern is recorded The effect of the photomask capable of obtaining a high yield is obtained.

  Further, according to the thermomagnetic transfer apparatus according to claim 6 of the present invention, the write head and the read head provided close to each other, the write head and the read head are each supported at one end thereof, A thermomagnetic transfer apparatus for writing a tracking pattern on a magnetic disk in a magnetic recording apparatus having an actuator that freely rotates on the magnetic disk, and is capable of covering from the inner periphery to the outer periphery of the magnetic disk A plurality of permanent magnets, and the plurality of permanent magnets or yokes have an arcuate locus when the write head and the read head move from the inner peripheral portion to the outer peripheral portion on the magnetic disk, and on the magnetic disk. At each intersection with each track, the angle formed by the tangent of the arc that is the trajectory when the head moves and the tangent of the track are divided into approximately two equal angles. Because it has a shape that can be formed to become narrower, it is possible to record a pattern that allows the same control as the burst pattern normally used in magnetic recording devices, and the servo tracking pattern is more accurate In addition to transferring the signal only to the circumferential component of the media, it is possible to simultaneously transfer the signal to the radial component of the media, and the pattern length can be shortened. It is possible to increase the number of servo tracking patterns written in one track, and there is an effect of obtaining a thermomagnetic transfer apparatus capable of obtaining a magnetic disk on which the servo tracking patterns are recorded with a high yield.

  According to a thermomagnetic transfer apparatus according to a seventh aspect of the present invention, in the thermomagnetic transfer apparatus according to the sixth aspect, the plurality of permanent magnets are arc-shaped permanent magnets having different curvatures from each other. Arc-shaped permanent magnets with different curvatures are arranged above and below the photomask so that the energy beam irradiation area sandwiched between the permanent magnets is narrow on the inner peripheral side of the photomask and wide on the outer peripheral side. As a result, it is possible to record patterns that enable the same control as the burst pattern used in a magnetic recording device, and it is possible to form a servo tracking pattern with higher accuracy, as well as the circumferential component of the media. It is possible not only to transfer signals but also to simultaneously transfer signals to the radial component of the media, and it is possible to shorten the pattern length Therefore, it is possible to increase the number of servo tracking patterns written on one track, and there is an effect of obtaining a thermomagnetic transfer apparatus capable of obtaining a magnetic disk on which the servo tracking patterns are recorded with a high yield. .

  In the magnetic disk according to the eighth aspect of the present invention, the servo tracking pattern is written by executing the servo tracking pattern writing method according to the first or second aspect. Pattern recording that enables the same control as the burst pattern used in the recording device is possible, servo tracking patterns can be formed with higher accuracy, and not only the signal is transferred only to the circumferential component of the media. Since it is possible to simultaneously transfer signals to the radial component of the medium and to shorten the pattern length, it is possible to increase the number of servo tracking patterns written in one track. A magnetic disk on which this servo tracking pattern is recorded can be obtained with a high yield. There is an effect.

  According to the magnetic disk of claim 9 of the present invention, when the servo tracking pattern writing method is executed on the magnetic disk of claim 8, the thermomagnetic transfer apparatus according to claim 6 or 7 is used. Because it is used, it is usually possible to record patterns that allow the same control as the burst pattern used in the magnetic recording device, so that the servo tracking pattern can be formed with higher accuracy and the circumferential direction of the media Not only can the signal be transferred to the component, but also the signal can be simultaneously transferred to the radial component of the media, and the pattern length can be shortened, so the servo tracking pattern written on one track It is possible to increase the number of magnetic disks on which the servo tracking pattern is recorded. There are remains in effect obtained.

(Embodiment 1)
Hereinafter, a servo tracking pattern writing method, a photomask, a thermomagnetic transfer apparatus, and a magnetic disk according to Embodiment 1 of the present invention will be described with reference to the drawings.

  First, using a dedicated head for DC erase, DC erase of the media is performed as shown in FIG. 1 (see step 101 in FIG. 4). Although this operation itself is the same as that of the conventional example shown in FIG. 16, the dedicated head used in this case is different from that of the conventional example.

  That is, as shown in FIG. 2, this DC erase head (dedicated head) 15 is a permanent magnet 19 with a yoke 18 attached to which track tr1 (,..., Trn) on the gap 18a. The angle (about 45 °) obtained by dividing the angle (about 90 °) between the track tangent t1 and the arc tangent n1 which is the locus when the head is moved into the tangent t2 of the gap 18a also at the intersection of The arc shape is 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. 3 may be used. The head of FIG. 3 is a mirror image of the gap shape of the head of FIG.

  The head dedicated for magnetic transfer is fixed at the position shown in FIG. 2, and either the magnet 19 or the medium 1 is rotated one or more times around the media center. The rotation direction may be either left rotation or right rotation. At this time, the distance between the magnet 19 and the medium 1 is 0.5 mm to 2 mm, and a signal actually transferred is confirmed and determined based on 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. 2 or FIG. 3, the direction of the permanent magnet is the ideal direction in the direction in which the digital part pattern is magnetized and the ideal direction in the direction in which the burst pattern is magnetized. It is desirable to be in the middle direction.

  Next, leave a space of several μm or less between the photomask and the media (if the yield does not matter, the photomask and the media may be in direct contact with each other). A photomask will be described here.

  The photomask forms a pattern to be transferred with a metal film on a glass substrate.

  The pattern used for the conventional magnetic transfer uses a pattern for phase control, and the pattern is two kinds of oppositely diagonal patterns (Zig, Zag) as shown in FIG. The normal pattern (Preamble) which becomes a shape is included. 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 glass portion (transparent portion) without the metal film that transmits energy rays and the width of the metal film are required to be 0.5 μm or more in the current photomask manufacturing process. Accordingly, 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 a narrow pattern width on the innermost periphery of the medium. The pattern width at the outer periphery of the media becomes wider in proportion to the radius.

  On the other hand, since the pattern of the present invention considers the conventional burst control method instead of the phase control, the burst pattern does not have a diagonal pattern as in the conventional case, and is stepped as shown in FIG. There are eight misaligned A, B, C, D, E, F, G, and H. The quantity of 8 is determined from the deviation pitch of each burst pattern. If the deviation pitch is changed, it can be a number other than 8. The width of the media in the radial direction of the glass part and the metal film part is 0.5 μm, and the length in the circumferential direction is 4 μm, which is the length of the conventional burst pattern in the servo signal at the innermost circumference of the medium. Even if each gap length is taken into consideration, it is 5 μm or less, and its 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 1/8 length of the pitch of the glass portion. There is no need to be particular about the order of the eight burst patterns from A to H. Further, it is not necessary to stick to 0.5 μm with respect to the radial width of the glass part and the metal film part. If a pattern of 0.5 μm or less can be created in the future, it can be used at that interval. Conversely, patterns of 0.5 μm or more can also be used. At that time, the adjustment may be performed by reducing or increasing the number of burst patterns. The ratio of the length in the radial direction of the glass part (N) and the metal film part (S) may not be 1: 1, and (N−S) / (N + S) falls within the ratio of + 40% to −40%. If so, positioning control is possible without problems. 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. Such a photomask is formed using a lithography technique (see step 102 in FIG. 4). As shown in FIG. 5, the photomask 20 includes a photomask body 20b that is transparent to energy rays, and a metal film 20a that is formed on one main surface and is opaque and patterned with respect to energy rays.

  Although the photomask on which such a pattern is formed and the medium are arranged with a space of several μm or less (see step 103 in FIG. 4), the yield is not a problem as described above. May be in contact with each other), which is not limited to the size of the media. The media can be made of either aluminum or glass substrate body.

  Thereafter, a magnetic field is applied from the surface of the photomask that does not have a metal film by using a yoke and permanent magnet having the same gap shape as that used for erasing the media, and an energy beam is generated by an energy beam generator 24 such as a surface emitting laser. (See step 104 of FIG. 4), unlike the case of magnetic transfer, in the case of thermomagnetic transfer, it is necessary to make energy rays incident between the yokes. Therefore, it is necessary to provide a predetermined interval between the yokes. If this interval is set wide on the inner peripheral side of the photomask, a DC excitation magnetic field is not applied to the track in a direction of about 45 °. On the other hand, the requirements on the outer peripheral side are not so strict. For this reason, as shown in FIG. 6, the permanent magnet 21a and the permanent magnet 21b are both curved toward the right side in the figure, but the curvature of the permanent magnet 21b is substantially constant, whereas the permanent magnet 21b is permanent. It is assumed that the curvature of the magnet 21a gradually increases toward the inside of the photomask 20, so that the inner peripheral side of the energy beam irradiation region A1 sandwiched between the permanent magnets 21a and 21b is narrow and the outer peripheral side is widened. ing.

By devising the shape of the permanent magnet in this way, it is possible to apply a magnetic field of about 45 ° to the track while being able to irradiate energy rays.
The direction of the magnetic field is preferably 180 ° opposite to that during erase.

  The thermomagnetic transfer device 25 shown in FIG. 6 has the same configuration as that of the conventional device shown in FIG. 25 except that the shape of the permanent magnet and the shape of the coil formed by winding a wire around the permanent magnet are different. That is, 2 having a shape curved to the right in the figure, arranged with the polarities (N, S) reversed to each other below the lower main surface of the media 1 and the upper main surface of the photomask 20 positioned relative to each other. By having a pair of rod-shaped permanent magnets 21a, 21b and 21c, 21d and winding a wire at positions corresponding to the three side surfaces of a substantially fan-shaped columnar body surrounded by two pairs of upper and lower permanent magnets An energy beam is formed on the energy beam irradiation region A1 on the photomask 20 sandwiched between the power source that generates the pulsed magnetic field by energizing the coil 22 and the permanent magnets 21a and 21b. And an energy beam generator 24 for irradiation.

  In this thermomagnetic transfer method, the medium 1 is DC erased in the same manner as the magnetic transfer method, and then a permanent magnet and a coil 22 for generating a pulsed magnetic field are installed as shown in FIG. The pulsed magnetic field and the energy beam are simultaneously irradiated several tens of times so that the energy beam is irradiated on the substrate. The magnetic field is a pulse magnetic field applied by permanent magnets 21a, 21b, 21c, 21d and an electromagnet (coil 22 + power source 23). In the permanent magnet, the magnetic flux is set so that the medium is not magnetized, and the pulse magnetic field is applied to compensate for the insufficient portion of the permanent magnet.

  Then, the power source 23 and the energy beam generator 24 are set so that the peak time of the energy beam output and the peak time of the pulse magnetic field are the same.

  The media thus created is incorporated into a magnetic recording device. A magnetic recording apparatus is a magnetic recording medium or a plurality of media, a rotor for rotating the medium, a rotor arm having one or a plurality of write heads and a read head, and a driving device for driving the rotor arm. And a circuit for writing signals and a circuit for reading signals. At least one magnetically transferred medium is incorporated into the magnetic recording device. One surface is sufficient for magnetic transfer. After the assembly, the head is positioned by the magnetically transferred signal in the test process of the magnetic recording apparatus, and the final servo tracking signal is written on all the heads of the magnetic recording apparatus and on the entire surface of the medium. A method for controlling the head positioning using the magnetic transfer signal will be described below.

  The pattern of the photomask of the present invention is as shown in FIG. 5, and the signal transferred to the medium of the burst signal portion A surrounded by the square Q in FIG. 5 is a three-dimensional graph as shown in FIGS. expressed. In this graph, the vertical axis represents the voltage when read by the head. FIG. 7 shows a signal transferred when the pattern of the present invention is transferred at a conventional transfer system, that is, at the same position as 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. is there. 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 glass portion 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. An object of the present invention is to position the head by reading the signals X1 and X2 in the circumferential direction. For each burst, a window is used to remove the portion of the burst signal that is expected to be noisy at the beginning and end, and the signal is captured and processed.

  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. Accordingly, 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 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. However, if one burst signal has one isolated waveform (one set on the plus side and one on the minus side), the reliability is inferior in reading the peak voltage of the burst signal due to electrical noise or the like. Therefore, the noise component is mitigated by writing a plurality of the isolated waveforms. In addition, it is desirable to shorten the servo pattern and burst signal as much as possible because they compress the data area. However, reducing the number of continuous solitary waveforms is limited for the reasons described above, the idea of increasing the write frequency and shortening the total length of the signal can be obtained. 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, the conventional burst signal requires a complicated method for obtaining the maximum voltage value of the signal of several tens of MHz in order to reproduce the signal and create a positioning signal for the head.

  In contrast, in the present invention, the magnetic recording direction is not limited to the circumferential direction, the digital signal portion is circumferentially transferred, and the analog signal portion burst signal is radially transferred in the radial direction. The direction is at an intermediate angle, ie 45 °. Therefore, when the pattern according to the first embodiment is thermomagnetically transferred by the magnetic transfer head according to the first embodiment, it is possible to read both the components magnetized in the circumferential direction and the radial direction.

  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 based on the voltage value of this signal, but the information of only 1 set (one isolated waveform for the burst signal, that is, one set of isolated waveforms on the plus side and minus side) is affected by noise. Since large and accurate head positioning cannot be performed, the accuracy of the signal is improved by writing a plurality of isolated waveforms in the form of a sine wave 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, the signal appears not as an isolated waveform but as a DC component voltage value. That is, the signal is not written with a constant frequency signal as written in the conventional burst signal. This eliminates the need for a complicated method for obtaining the peak voltage of a signal having a constant frequency after reading.

  FIG. 10 is a graph showing the read voltage value of each burst according to the present invention for each head position (radial direction). The width of the glass part forming the burst is 0.5 μm, the distance between the glass parts is 0.5 μm, the number of burst signals is 8, and the names of the burst signals are from A, B, C, D, E, F, G, H. The radial deviation of the burst signals adjacent to the eight glass parts forming each burst signal is 1/8 with respect to the pitch of the glass parts, and the deviation directions are all the same direction (A burst). Therefore, it is assumed that the B burst is shifted to 1/8 (1/8 μm) of the pitch of the glass portion on the inner peripheral 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 glass portion pitch with respect to the burst signal. 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, these problems can be solved by adding the values of some of these eight burst signals to the value of one burst signal.

  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 is eight, which is the same as the number of original burst signals. 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, the difference between A ′ and E ′ in which the voltage values are opposite to each other, that is, the waveforms of A′−E ′, B′−F ′, C′−G ′, and D′−H ′ is confirmed. 13, the rising edge and the falling edge are linear, indicating 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 is 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 the rising straight portions of the four waveforms have many portions that overlap each other, it is possible to know 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 that time, increasing the number of burst signals to be 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 is determined that there is a possibility that this burst signal can be used up to about 600 KTPI 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 may occur due to the effect of diffraction of laser light that passes through the photomask during magnetic transfer when the width of the glass portion becomes wider or narrower in the process of creating the photomask. However, in any of these cases, the center position of the glass portion and the center position of the metal film portion of the read signal do 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 are respectively intersections with the X axis. Are the same. Therefore, the signal asymmetry which is the cause of these can be corrected almost completely.

  FIG. 15 shows a head positioning control circuit that adds and subtracts a plurality of such waveforms to generate a signal with linearity at the rising or falling part, and performs signal processing on this to position the head. An example of a part of 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 among these eight types of signals A, B, C, D, E, F, G, and H.

A, B, C
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 are

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.

  As described above, according to the first embodiment, a burst pattern having the following characteristics can be formed on a medium with a high yield and a sharp shape, and the burst pattern can be formed with a sharp shape. A clean signal shape can be obtained, and high-precision head positioning of a hard disk drive using this medium can be realized.

  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.

  In the first embodiment, the width of the glass part is 0.5 μm and the distance between the glass parts is 0.5 μm. However, the present invention is not limited to these values.

  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 writing method according to the present invention enables positioning of the head of the magnetic recording apparatus with high accuracy, and can transfer the tracking pattern so that the circumferential length of the transfer signal is shortened. Therefore, it is suitable for use in improving the recording density of the magnetic recording apparatus.

It is a figure which shows the mode of the DC erase of the medium in the thermomagnetic transfer method by Embodiment 1 of this invention. It is a figure which shows an example of the head for erase used in the thermomagnetic transfer method by Embodiment 1 of this invention. It is a figure which shows another example of the erase head used in the thermomagnetic 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 pattern formed in the photomask used for the thermomagnetic transfer method by Embodiment 1 of this invention. It is a figure which shows an example of the structure of the thermomagnetic transfer apparatus used for the thermomagnetic transfer method by Embodiment 1 of this invention. It is a figure which shows the signal when the disk pattern of the master disk used for the thermomagnetic 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 thermomagnetic transfer apparatus 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 DC erase 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. It is a figure which shows schematic structure of the thermomagnetic transfer apparatus used for the conventional thermomagnetic transfer method. It is a figure which shows schematic structure of the thermomagnetic transfer apparatus used for the conventional thermomagnetic 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 8, 18 Yoke 8a, 18a Gap 9, 19, 21a, 21b, 21c, 21d, 210a, 210b, 210c, 210d Permanent magnet 10, 15 DC erase head 14 Read head 20 Photomask 25, 250 Thermomagnetic transfer device 101, 201 Perform DC erase Steps 102 and 202 Steps for creating a master disk 103 Steps for arranging a medium and a photomask at intervals 203 Steps for superimposing a medium and a master disk 104 Steps for performing thermomagnetic transfer 204 Steps for performing magnetic transfer 105 and 205 Hard Steps for assembling disk drives 106, 206 Steps for performing self-servo write 151 Head amplifier 152 Sample value acquisition circuit 153 Signal separation circuit 154 Signal continuity detection circuit 155, 156, 157, 158, 159, 160, 161, 162 Adder circuit 163 , 164, 165, 166 Subtraction circuit 170 Window setting circuit 171 Signal processing circuit L1, L2 L-shaped peak tr1,..., Trn Track t1 Track tangent t2 Head gap tangent n1 Arc of the trajectory when the head moves Tangent

Claims (9)

Magnetism in a magnetic recording apparatus having a write head and a read head provided close to each other, and an actuator that is supported at one end of each of the write head and the read head and that freely rotates on the magnetic disk. In the method of writing the tracking pattern to the disc,
DC erasing the magnetic disk;
A photomask substrate transparent to energy rays, and a thermomagnetic transfer tracking pattern to be transferred to the magnetic disk, which is made of a material opaque to the energy rays on one main surface of the photomask substrate, is opaque. A step of positioning a photomask composed of a mask pattern layer formed by the presence or absence of a material and the magnetic disk with an interval of several μm or less;
While applying the magnetic field to the magnetic disk in a direction opposite to the erased direction and at an angle of about 45 degrees with respect to the track in a state where the magnetic disk and the photomask are arranged with an interval of several μm or less. Irradiating the energy beam from the photomask side, and thermomagnetically transferring the thermomagnetic transfer pattern on the photomask to the magnetic disk.
And a servo tracking pattern writing method. The servo tracking pattern writing method according to claim 1,
The thermomagnetic transfer tracking 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 transparent portion representing the second pattern is a parallelogram, and the two sides are composed of two straight lines approximating an arc parallel to the circumferential track direction, and the remaining two sides are the write head, And two parallel straight lines approximating a circular arc when the read head moves between the inner peripheral portion and the outer peripheral portion on the magnetic disk,
The first pattern and the second pattern are formed at an interval greater than the interval required in the photomask manufacturing process.
And a servo tracking pattern writing method. Magnetism in a magnetic recording apparatus having a write head and a read head provided close to each other, and an actuator that is supported at one end of each of the write head and the read head and that freely rotates on the magnetic disk. A photomask for writing a tracking pattern on a disc,
A photomask substrate that is transparent to the energy rays used to transfer the tracking pattern onto the magnetic disk;
On one main surface of the photomask substrate, a mask pattern layer made of a material opaque to the energy rays, and formed with a thermomagnetic transfer tracking pattern to be transferred to the magnetic disk,
Furthermore, the tracking pattern for thermomagnetic transfer 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 second pattern is a parallelogram, and the two sides consist of two straight lines approximating a circular arc parallel to the circumferential track direction, and the remaining two sides are the write head and the read head. Consists of two straight lines approximating a circular arc when moving between the inner and outer perimeters on the magnetic disk,
The first pattern and the second pattern are formed with an interval larger than the interval required in the photomask manufacturing process.
A photomask characterized by that. The photomask according to claim 3, wherein
The shape of the transparent portion forming the burst signal pattern is such that the radial direction is longer than the minimum pattern that can be manufactured in the photomask manufacturing process, and the circumferential direction is several μm for the burst signal in the inner periphery of the magnetic disk. The burst signal at the outer periphery of the magnetic disk has a length proportional to the radius of the magnetic disk,
The distance between adjacent burst signal patterns is longer than the minimum distance that can be manufactured in the photomask manufacturing process in the radial direction, and the burst signal in the circumferential direction of the magnetic disk can be manufactured in the photomask manufacturing process. A length greater than the minimum interval, and the burst signal on the outer periphery of the magnetic disk has a length proportional to the radius,
The second pattern is formed so that n types of burst signals (n is an integer of 2 or more) are shifted from each other at an interval of 1 / n of the pitch of the transparent portion in the radial direction. ,
A photomask characterized by that. The photomask according to claim 3, wherein
The burst signal pattern further has a shape in which the burst signal patterns adjacent to each other in the circumferential direction are joined with a transparent portion interposed therebetween,
A photomask characterized by that. Magnetism in a magnetic recording apparatus having a write head and a read head provided close to each other, and an actuator that is supported at one end of each of the write head and the read head and that freely rotates on the magnetic disk. A thermomagnetic transfer device for writing a tracking pattern on a disk,
A plurality of permanent magnets of a length that can cover the inner periphery to the outer periphery of the magnetic disk;
The plurality of permanent magnets or yokes are heads at each intersection of an arcuate locus and each track on the magnetic disk when the write head and read head move from the inner periphery to the outer periphery on the magnetic disk. A shape formed so as to be equal to an angle obtained by dividing the angle formed by the tangent line of the circular arc and the tangent line of the track, which is a trajectory at the time of the movement, into about two equal parts,
A thermal magnetic transfer apparatus characterized by that. The thermomagnetic transfer apparatus according to claim 6, wherein
The plurality of permanent magnets are arc-shaped permanent magnets having different curvatures from each other,
The arc-shaped permanent magnets having different curvatures are arranged above and below the photomask so that the energy beam irradiation region sandwiched between the permanent magnets is narrow on the inner peripheral side of the photomask and wide on the outer peripheral side. Being
A thermal magnetic transfer apparatus characterized by that. A servo tracking pattern is written by executing the servo tracking pattern writing method according to claim 1,
A magnetic disk characterized by that. The magnetic disk according to claim 8, wherein
When the servo tracking pattern writing method is executed, the thermomagnetic transfer device according to claim 6 or 7 is used.
A magnetic disk characterized by that.

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