JP2009266352A - Magnetic recording medium, magnetic recording device, control apparatus, and method for manufacturing magnetic recording medium - Google Patents

Abstract

A magnetic recording medium, a magnetic recording apparatus, a control apparatus, and a magnetic recording medium manufacturing method capable of stabilizing the magnetization direction of a magnetic material forming a servo pattern.
Of the servo patterns formed by the magnetic material arrangement pattern of the magnetic recording medium, the preamble and the servo synchronization signal portion are mainly magnetized in the positive electrode and magnetized in the negative electrode. By alternately arranging the body, the magnetization direction of the magnetic body forming the servo pattern is stabilized.
[Selection] Figure 3-1

Description

  The present invention relates to a magnetic recording medium, a magnetic recording apparatus, a control apparatus, and a magnetic recording medium manufacturing method.

  In some magnetic recording media, servo information is determined by an arrangement pattern (called a servo pattern) of a magnetic material formed in a servo area. The servo pattern is mastered by, for example, an electron beam (EB) drawing device or the like, and after the magnetic material in the servo area is shaved into a predetermined pattern by etching, the servo material is uniformly applied to the remaining magnetic material. Generated by applying a magnetic field. The manufacturer uses a stamper mastered by an electron beam drawing apparatus or the like to create a servo pattern by copying, thereby shortening the time for generating the servo pattern.

  Such a servo pattern is often used not only in a conventional magnetic recording medium but also in a discrete track medium and a patterned medium, which have been studied recently. A discrete track medium is a magnetic recording medium in which tracks are separated by a non-magnetic material, and a patterned medium is a magnetic recording medium in which minute magnetic particles are isolated by a non-magnetic material. It is.

JP 2001-148110 A JP 2003-16621 A

  However, the magnetic recording medium having the servo pattern as described above has a problem that the magnetization direction of the magnetic material forming the servo pattern becomes unstable. This problem will be specifically described. As described above, since the conventional servo pattern is generated by uniformly applying a magnetic field to the magnetic material, the magnetization directions of the magnetic materials forming the servo pattern are all the same. Therefore, since the magnetization direction of each magnetic body is opposite to the direction of the magnetic field created by the adjacent magnetic body, each magnetic body may be reversed in magnetization due to the influence of the magnetic field of the adjacent magnetic body.

  When the magnetic material forming the servo pattern is reversed in magnetization, the head cannot read the servo signal from the magnetic recording medium, so that the following control or the like cannot be performed with high accuracy. In a magnetic recording apparatus, since it is a serious problem that the accuracy of following control is lowered, it has been desired to realize a technique capable of stabilizing the magnetization direction of each magnetic material forming a servo pattern.

  The disclosed technology has been made to solve the above-described problems caused by the conventional technology, and can provide a magnetic recording medium, a magnetic recording device, a control device, and a magnetic recording medium that can stabilize the magnetization direction of a magnetic material forming a servo pattern. An object of the present invention is to provide a magnetic recording medium manufacturing method.

  In order to solve the above-described problems and achieve the object, the magnetic recording medium disclosed in the present application includes a plurality of magnetic areas forming the servo area, in which a servo area including servo information is formed by a magnetic material arrangement pattern. It is a requirement that the body is magnetized alternately with the positive and negative electrodes.

  Further, the control device disclosed in the present application is a control device that controls a magnetic recording medium manufacturing device that manufactures a magnetic recording medium having a servo area in which servo information is configured by a magnetic material arrangement pattern. Based on a servo signal read from the area, a servo control unit that performs following control for causing the head to follow a target position on the magnetic recording medium, and causes the servo control unit to follow the head on a predetermined track. And a bipolar unit for performing a bipolar process, which is a process of alternately magnetizing a plurality of magnetic bodies forming a servo region on the track to the positive and negative electrodes with respect to the head. .

  In addition, the magnetic recording medium disclosed in the present application and any combination of the constituent elements, expressions, or constituent elements of the control apparatus applied to a method, apparatus, system, computer program, recording medium, data structure, etc. It is effective as

  According to the magnetic recording medium disclosed in the present application, it is possible to stabilize the magnetization direction of the magnetic material forming the servo pattern.

  Embodiments of a magnetic recording medium, a magnetic recording apparatus, a control apparatus, and a magnetic recording medium manufacturing method disclosed in the present application will be described below in detail with reference to the drawings. The embodiment does not limit the magnetic recording medium, the magnetic recording apparatus, the control apparatus, and the magnetic recording medium manufacturing method disclosed in the present application.

  First, the configuration of the magnetic recording apparatus 1 including the magnetic recording medium 10 according to the present embodiment will be described. FIG. 1 is a diagram showing a configuration of the magnetic recording apparatus 1. The magnetic recording medium 10 shown in FIG. 1 has a servo area that stores servo information and the like, and a user area that stores user information. The servo information is data used for positioning control of the head 13. The servo area of the magnetic recording medium 10 according to the present embodiment is formed by a servo pattern.

  The magnetic recording medium 10 is rotationally driven by a spindle motor 11. Reading and writing of the magnetic recording medium 10 is performed by a head 13 provided at one end of an arm 12 that is a head support mechanism. The head 13 performs reading and writing while maintaining a state slightly lifted from the surface of the magnetic recording medium 10 by lift generated by the rotation of the magnetic recording medium 10. Further, the arm 12 rotates on an arc around the axis 15 by driving a voice coil motor (hereinafter abbreviated as “VCM”) 14 which is a head driving mechanism provided at the other end of the arm 12. Then, the head 13 seeks in the track crossing direction of the magnetic recording medium 10 to change the track to be read / written.

  Next, an outline of the magnetic recording medium 10 according to the present embodiment will be described. Here, in order to clarify the characteristics of the magnetic recording medium 10 according to the present embodiment, first, the servo pattern of the conventional magnetic recording medium 90 will be described, and then the magnetic recording medium 10 according to the present embodiment will be described. The servo pattern which has is demonstrated.

  FIG. 2A is a diagram illustrating an example of a servo pattern 900 included in the conventional magnetic recording medium 90. FIG. 2A shows a servo pattern 911 formed in one sector among the servo patterns 900 included in the magnetic recording medium 90. In this specification, each sector in the servo area is referred to as a “servo sector”. As illustrated in FIG. 2A, the servo pattern 911 includes a preamble section 911a, a servo synchronization signal section 911b, an address section 911c, and an amplitude burst section 911d in the order in which the head 13 reads.

  The preamble portion 911a is an area where a magnetic material is arranged so that a reproduction signal having a constant frequency is read out. The magnetic recording device 1 uses a processing clock signal for analyzing a signal read from the servo pattern 911 (hereinafter referred to as “servo signal”) based on a reproduction signal having a constant frequency read from the preamble section 911a. The phase is adjusted, and the gain for maintaining the amplitude of the servo signal is adjusted. The servo synchronization signal portion 911b is a region where a magnetic material is arranged so that a reproduction signal indicating the start of the address portion 911c is read out.

  The arrangement pattern of the magnetic material forming the preamble portion 911a and the servo synchronization signal portion 911b is the same in all sectors, and is formed by a magnetic material and a non-magnetic material that are connected from the center side to the outside of the magnetic recording medium 90. Is done.

  The address portion 911c is an area where a magnetic material is arranged so that a reproduction signal indicating a track number and a sector number in the magnetic recording medium 90 is read out. The arrangement pattern of the magnetic material forming the address portion 911c is different for each servo sector. Note that information read from the address portion 911c is usually converted by a Gray code.

  The amplitude burst unit 911d has a magnetic body arranged so that the amplitudes of the reproduction signals read from the burst unit A and the burst unit B shown in FIG. 2-1 are different when the head 13 is not positioned at the center of the track. It is an area that has been. The magnetic recording apparatus 1 positions the head 13 at the center of the track based on the reproduction signal read from the burst portions A and B. The burst portions C and D shown in FIG. 2A have a phase difference of 90 [°] with respect to the burst portions A and B, and the magnetic recording apparatus 1 reads the reproduction signal read from the burst portions C and D. Based on the above, the head 13 may be positioned at the center of the track.

  The servo pattern 900 formed in this way is prepared by etching a pattern transferred and copied to a resist or the like using a stamper mastered by an electron beam drawing apparatus or the like. After the magnetic material in the servo area is cut into a predetermined pattern as shown in FIG. 2A, the magnetic material is generated by applying a uniform magnetic field to the uncut magnetic material. That is, the magnetization directions of the magnetic bodies forming the servo pattern 900 are all the same. This has caused a problem that the magnetization direction of each magnetic material forming the servo pattern 900 becomes unstable.

  Such a problem will be specifically described with reference to FIG. FIG. 2-2 is a cross-sectional view taken along line AA shown in FIG. As shown in FIG. 2B, the AA portion of the servo pattern 911 shown in FIG. 2A is formed by laminating magnetic bodies J91 to J94 on the substrate. And the magnetic bodies J91-J94 are magnetized by the positive electrode. In the present specification, the vertical direction from the substrate to the magnetic material is referred to as “positive electrode”, and the vertical direction from the magnetic material to the substrate is referred to as “negative electrode”.

  The magnetic field created by the magnetic body J91 is represented by magnetic lines of force M91a to M91c, and the magnetic field created by the magnetic body J93 is represented by magnetic lines of force M93a to M93c. Among the magnetic lines of force, the direction of the magnetic lines of force M91c is opposite to the direction of magnetization of the magnetic body J92. Therefore, the magnetic lines of force M91c may cause magnetization reversal of the magnetic body J92. Similarly, the magnetic field lines M93b may cause magnetization reversal of the magnetic body J92. That is, the magnetic body J92 may be reversed in magnetization due to the influence of the magnetic field created by the adjacent magnetic bodies J91 and J93.

  The same can be said about other magnetic bodies other than the magnetic body J92 in that there is a possibility of magnetization reversal. Each magnetic body forming the servo pattern 911 is affected by the magnetic field created by the adjacent magnetic body. There is a risk of magnetization reversal. The coercive force differs depending on the magnetic material. When a magnetic material having a weak coercive force is present in the magnetic material forming the servo pattern, the magnetic material is likely to undergo magnetization reversal. When the magnetic material forming the servo pattern is reversed in magnetization, the servo signal cannot be accurately read out from the magnetic recording medium, so that the following control or the like cannot be performed with high accuracy. In the magnetic recording apparatus, it is an important problem that the accuracy of following control is lowered. Therefore, it has been desired to realize a technique capable of stabilizing the magnetization direction of each magnetic material forming the servo pattern.

  Therefore, in the magnetic recording medium 10 according to the present embodiment, in order to stabilize the magnetization direction of the magnetic material, the servo pattern is alternately formed of a magnetic material magnetized on the positive electrode and a magnetic material magnetized on the negative electrode. Place and form. FIG. 3A is a diagram illustrating an example of a servo pattern included in the magnetic recording medium 10 according to the present embodiment. FIG. 3A shows a servo pattern 111 formed in one sector among the servo patterns 100 of the magnetic recording medium 10. As shown in FIG. 3A, the servo pattern 111 includes a sync mark portion 111e, a preamble portion 111a, a servo synchronization signal portion 111b, an address portion 111c, and an amplitude burst portion 111d in the order in which the head 13 reads. Has been placed. FIG. 3A shows an example in which the sync mark portion 111e is arranged at the head in the order in which the head 13 reads, but the sync mark portion 111e is arranged at the tail in the order in which the head 13 reads. May be.

  The sync mark portion 111e is a region where a magnetic material is arranged so that a reproduction signal used for bipolar processing described later is read out. The length of the circumferential side of the magnetic material arranged in the sync mark portion 111e is the distance between the magnetic materials arranged in the preamble portion 111a, the servo synchronization signal portion 111b, the address portion 111c, and the amplitude burst portion 111d. equal. The bipolar processing using the reproduction signal read from the sync mark unit 111e will be described in detail later.

  The preamble part 111a, the servo synchronization signal part 111b, the address part 111c, and the amplitude burst part 111d are similar to the preamble part 911a included in the above-described conventional magnetic recording medium 90 and the like, and a reproduction signal indicating predetermined information is transmitted. The magnetic bodies are arranged in a predetermined pattern so as to be read out.

  In FIG. 3A, the magnetic substance indicated by the black rectangle is magnetized in the positive electrode, and the magnetic substance indicated by the hatched rectangle is magnetized in the negative electrode. That is, in the preamble part 111a and the servo synchronization signal part 111b, the magnetic body magnetized in the positive electrode and the magnetic body magnetized in the negative electrode are alternately arranged. Thus, in the preamble part 111a and the servo synchronization signal part 111b in which the magnetic body is arranged, the magnetization direction of the magnetic body is stabilized.

  This will be specifically described with reference to FIG. 3-2 is a diagram illustrating a cross-sectional view taken along line BB illustrated in FIG. 3-1. As shown in FIG. 3B, the BB portion of the servo pattern 111 shown in FIG. 3A is formed by laminating magnetic bodies J11 to J14 on the substrate. The magnetic bodies J11 and J13 are magnetized in the positive electrode, and the magnetic bodies J12 and J14 are magnetized in the negative electrode.

  The magnetic field created by the magnetic body J11 is represented by magnetic lines M11a to M11c, the magnetic field created by the magnetic body J12 is represented by magnetic lines of force M12a to M12c, and the magnetic field created by the magnetic body J13 is represented by magnetic lines of force M13a to M13c. The magnetic field created by J14 is represented by magnetic field lines M14a to M14c. Among the magnetic lines of force, the directions of the magnetic lines of force M11c and M13b are the same as the direction of magnetization of the magnetic body J12, so that the magnetic bodies J11 and J13 stabilize the magnetization direction of the magnetic body J12. Moreover, since the direction of the magnetic force lines M12c and M14b is the same as the magnetization direction of the magnetic body J13, the magnetic bodies J12 and J14 stabilize the magnetization direction of the magnetic body J13.

  As described above, in the magnetic recording medium 10 according to the present embodiment, the preamble portion 111a and the servo synchronization signal portion 111b of the servo pattern 100 alternate between the magnetic material magnetized in the positive electrode and the magnetic material magnetized in the negative electrode. Therefore, the magnetization direction of each magnetic material forming the preamble part 111a and the servo synchronization signal part 111b can be stabilized. This makes it difficult to reverse the magnetization of the magnetic material forming the servo pattern, so that the magnetic recording apparatus 1 having the magnetic recording medium 10 can read out a high-quality servo signal from the servo pattern 100. The following control can be performed with high accuracy.

  Note that the reason why only the preamble part 111a and the servo synchronization signal part 111b are bipolar is that bipolar processing described later can be performed efficiently. Specifically, as described above, the preamble portion 111a and the servo synchronization signal portion 111b are formed of a magnetic material and a non-magnetic material that are connected from the center side to the outside of the magnetic recording medium 10. Therefore, the magnetic material as a whole can be magnetized only by applying a magnetic field to the magnetic material formed in the predetermined servo sector, and the bipolar treatment can be performed efficiently.

  Next, the manufacturing procedure of the magnetic recording medium 10 according to this embodiment will be described. FIG. 4 is a flowchart showing the manufacturing procedure of the magnetic recording medium 10 according to this embodiment. As shown in FIG. 4, first, after the magnetic material in the servo area of the magnetic recording medium 10 is cut into a predetermined pattern as shown in FIG. 3A (step S11), the remaining magnetic material is removed. A magnetic field is uniformly applied (step S12). At this point, all the magnetic bodies forming the servo pattern 100 are magnetized to the same polarity (in this embodiment, the positive electrode).

  Thereafter, the magnetic recording medium 10 is mounted on the magnetic recording device 1 (step S13). The magnetic recording apparatus 1 on which the magnetic recording medium 10 is mounted has a predetermined magnetic property so that the magnetic material forming the preamble part 111a and the servo synchronization signal part 111b of the servo pattern 100 is alternately magnetized to the positive electrode and the negative electrode. A magnetic field is applied to the body (step S14). In this way, the magnetic recording medium 10 is manufactured. Below, each process of the manufacturing procedure of the magnetic recording medium 10 is demonstrated more concretely.

  First, in the magnetic recording medium 10, the magnetic material in the servo area is cut into a predetermined pattern by STW such as an electron beam drawing apparatus. At this time, as shown in FIG. 5, the magnetic recording medium 10 has a distance D1 between the magnetic bodies corresponding to one period of the servo signal and a circumferential width of the magnetic body forming a portion other than the sync mark portion 111e. The magnetic body is cut so that the ratio with S1 is “1: 0.6” to “1: 0.9”. FIG. 5 is a diagram for explaining the relationship between the distance between the magnetic bodies and the length of the sides in the circumferential direction of the magnetic bodies. As an example, the magnetic bodies J11 and J12 shown in FIG. Show. Further, in this specification, the length of the side of the magnetic body in the circumferential direction when the distance between the magnetic bodies is “1” is referred to as “Duty ratio”.

  The reason why the magnetic material such as the preamble portion 111a is cut so that the duty ratio becomes “0.6” to “0.9” will be described. This is because the servo read out from the servo pattern when the duty ratio is “0.6” to “0.9” when the servo pattern is formed by alternately arranging the positive and negative magnetic bodies. This is because the signal-to-noise ratio (hereinafter referred to as “SNR: Signal to Noise Ratio”) of the signal is the highest quality value.

  This will be described using specific measurement results. FIG. 6A is a diagram illustrating a waveform of a servo signal when the duty ratio is “0.2”. FIG. 6B is a diagram illustrating a waveform of the servo signal when the duty ratio is “0.5”. FIG. 6C is a diagram illustrating a waveform of the servo signal when the duty ratio is “0.8”. 6A to 6C show the servo signal after being amplified by the preamplifier, and the slope coefficient kp used when generating the waveform of the servo signal is set to “0.7”. .

  It is known that the SNR of the servo signal becomes a good value when the servo signal draws a waveform like a sine wave. The waveform of the servo signal shown in FIG. 6A does not draw a waveform like a sine wave and is distorted. That is, it can be seen that when the duty ratio is “0.2”, the SNR of the servo signal does not become a good value. Similarly, since the waveform of the servo signal shown in FIG. 6B is also distorted, it can be understood that the SNR of the servo signal does not become a good value even when the duty ratio is “0.5”. . On the other hand, the waveform of the servo signal shown in FIG. 6-3 depicts a waveform like a sine wave, and when the duty ratio is “0.8”, the SNR of the servo signal becomes a good value. I understand.

  The SNR of the servo signal when the duty ratio and the slope coefficient kp are other values will be described with reference to FIG. FIG. 7 is a diagram showing a distribution of SNR corresponding to the duty ratio and the slope coefficient kp. The horizontal axis in FIG. 7 indicates the duty ratio, and the vertical axis in FIG. 7 indicates the slope coefficient kp. Note that the SNR shown in FIG. 7 indicates that the larger the value, the higher the quality.

  As shown in FIG. 7, it can be seen that the SNR is the best value when the duty ratio is “0.6” to “0.9” whatever the slope coefficient kp is. Specifically, as shown in FIG. 7, when the duty ratio is “0.1” to “0.15”, the SNR is approximately “16” to “18”, and the duty ratio is “0.2”. ”To“ 0.25 ”, the SNR is approximately“ 18 ”to“ 20 ”. Similarly, when the duty ratio is “0.3” to “0.55”, the SNR is approximately “20” to “26”. On the other hand, when the duty ratio is “0.6” to “0.9”, the SNR is approximately “26” to “30”, which is the best value.

  Based on such measurement results, the servo pattern 100 included in the magnetic recording medium 10 according to the present embodiment forms a preamble portion 111a, a servo synchronization signal portion 111b, an address portion 111c, and an amplitude burst portion 111d. The magnetic body is cut so that the duty ratio becomes “0.6” to “0.9”. Thereby, the magnetic recording apparatus 1 can read out a high-quality servo signal from the servo pattern 100, and can perform following control with high accuracy.

  After the magnetic material in the servo region is shaved, a magnetic field is uniformly applied to the remaining magnetic material, and all the magnetic material in the servo region is magnetized to the positive electrode. After that, the magnetic recording device 1 on which the magnetic recording medium 10 is mounted is predetermined so that the magnetic material forming the preamble portion 111a and the servo synchronization signal portion 111b of the servo pattern 100 is alternately magnetized to the positive electrode and the negative electrode. A magnetic field is applied to the magnetic material.

  Next, the functional configuration of the magnetic recording apparatus 1 will be described. FIG. 8 is a diagram showing a functional configuration of the magnetic recording apparatus 1. As shown in FIG. 8, the magnetic recording apparatus 1 includes a magnetic recording medium 10, a head 13, a VCM 14, a preamplifier 16, a read channel 17, a hard disk (hereinafter abbreviated as "HD") controller 18, A power controller 19 and an MPU (Micro Processing Unit) 20 are included. The MPU 20 may be an MCU (Micro Controller Unit) or a CPU (Central Processing Unit).

  The magnetic recording medium 10 shown in FIG. 8 has servo areas 110 to 160. In each of the servo areas 110 to 160, magnetic materials are arranged in a predetermined pattern, and a servo pattern is formed. In addition, when all the servo patterns formed in the servo areas 110 to 160 are shown, they are called servo patterns 100. The preamplifier 16 is disposed in the vicinity of the head 13, pre-amplifies the weak reproduction signal read by the head 13, and outputs it to the read channel 17.

  The read channel 17 amplifies the reproduction signal input from the preamplifier 16 to maintain the amplitude of the reproduction signal constant, or performs AD conversion or demodulation on the reproduction signal. The reproduction signal includes a recording / reproduction signal that is a signal read from the user area and a servo signal that is a signal read from the servo area. Further, when receiving input of data (user data) from the HD controller 18, the read channel 17 performs code modulation of data to be written and outputs the data to the preamplifier 16.

  The read channel 17 uses a processing clock for analyzing the servo signal when performing amplification processing, AD conversion processing, demodulation processing, or the like on the reproduction signal read from the preamble section 111a and the servo synchronization signal section 111b. The frequency is switched twice and the gain for amplifying the servo signal is switched to half. This is because the servo pattern 100 of the magnetic recording medium 10 according to the present embodiment includes a portion formed by the positive and negative magnetic bodies and a portion formed only by the positive magnetic body. is there. That is, the frequency and amplitude of the servo signal read from the servo pattern 100 change in the middle of the signal. Specifically, the reproduction signal read from the preamble part 111a and the servo synchronization signal part 111b has a half frequency and amplitude compared to the reproduction signal read from the address part 111c and the amplitude burst part 111d. Doubled. The read channel 17 can accurately analyze the servo signal by switching the frequency and gain of the processing clock.

  The HD controller 18 receives a command from the host computer, controls the operation of the magnetic recording apparatus 1, and performs an error check on data transferred between the host computer and the magnetic recording apparatus 1. For example, the HD controller 18 receives input of data (user data) from the host computer, adds an error correction code to the data, and outputs the data to the read channel 17. For example, the HD controller 18 receives an input of a reproduction signal from the read channel 17, performs error correction as necessary, and outputs it to the MPU 20 or the host computer.

  The power controller 19 generates a VCM drive current for driving the VCM 14 based on the VCM control signal received from the MPU 20, and outputs the generated VCM drive current to the VCM 14.

  The MPU 20 is a control unit that performs main control of the magnetic recording apparatus 1 and positioning control of the head 13 by a predetermined control program (firmware program), and includes a servo control unit 21 and a bipolar unit 22.

  The servo control unit 21 is a processing unit that controls the positioning of the head 13 at a predetermined position. Specifically, when receiving a command from the host computer, the servo control unit 21 decodes the command and calculates a target position in the magnetic recording medium 10 for reading and writing data. Subsequently, the servo control unit 21 receives a servo signal read from the magnetic recording medium 10 by the head 13 via the preamplifier 16, the read channel 17, and the HD controller 18, and uses the servo signal to print the head 13. The current position of is calculated.

  Subsequently, the servo control unit 21 generates a VCM control signal based on the distance from the current position of the head 13 to the target position, and outputs the generated VCM control signal to the power controller 19. The power controller 19 that has received the VCM control signal outputs a VCM drive current to the VCM 14 to drive the VCM 14. In this way, positioning control of the head 13 is performed by the servo control unit 21.

  Thereafter, the servo control unit 21 performs following control (also referred to as on-track control or track following control) that causes the head 13 to follow the track on the magnetic recording medium 10. Specifically, the servo control unit 21 receives a servo signal read from the magnetic recording medium 10 by the head 13 after the head 13 is positioned and controlled. The servo control unit 21 calculates the current position of the head 13 and outputs a VCM control signal to the power controller 19 so that the positional deviation between the current position and the target position becomes zero. The power controller 19 that has received the VCM control signal inputs the VCM drive current to the VCM 14 and drives the VCM 14, whereby the head 13 moves to the target position.

  The bipolar section 22 is a bipolar process for applying a magnetic field to a predetermined magnetic body so that the magnetic bodies forming the preamble section 111a and the servo synchronization signal section 111b of the servo pattern 100 are alternately magnetized to the positive electrode and the negative electrode. To control. The bipolar unit 22 bipolarizes the magnetic body forming the servo pattern 100 by performing the bipolar process a plurality of times.

  Specifically, when the bipolar unit 22 receives an instruction to start bipolar processing from a host computer or the like, the servo unit 21 reads the servo read from the servo areas 110 to 160. Instead of using all signals, it is instructed to perform following control using some servo signals intermittently. The bipolar unit 22 performs bipolar processing on the servo areas 110 to 160 that are not used for the following control while the servo control unit 21 performs the following control.

  Subsequently, the bipolar unit 22 instructs the servo control unit 21 to perform the following control using a servo signal that has not been used last time among the servo signals read from the servo areas 110 to 160. Then, the bipolar unit 22 performs bipolar processing on the servo areas 110 to 160 that are not used for the following control. The reason why the bipolar process is not performed on the servo area used for the following control is that the write process cannot be executed on the servo area from which the servo signal is read.

  An example will be described with reference to FIG. FIG. 9 is a diagram showing an example of bipolar processing performed on the magnetic recording medium 10 shown in FIG. FIG. 9 shows servo patterns 111, 121, 131, 141, 151, and 161 formed in one servo sector in each of the servo areas 110 to 160 in the servo pattern 100 shown in FIG. For example, the servo pattern 111 is a servo pattern formed in one servo sector in the servo area 110. In FIG. 9, the magnetic material indicated by a rectangle with four lines vertically is magnetized only in the positive electrode, and the magnetic material indicated by a rectangle with two lines vertically is the positive electrode and the negative electrode. Indicates that it is magnetized.

  In the example shown in FIG. 9, the bipolar unit 22 sends the servo patterns 111 and 131 out of the servo signals read from the servo patterns 111, 121, 131, 141, 151 and 161 to the servo control unit 21. Following control is performed using the servo signals read out from 151 and 151. Then, the bipolar unit 22 performs bipolar processing on the servo patterns 121, 141, and 161 for which the servo signal is not used (step S21).

  Subsequently, the bipolar unit 22 causes the servo control unit 21 to perform the following control using the servo signals read from the servo patterns 121, 141, and 161, and the servo pattern 111, which has not been used for the following control, Bipolarization processing is performed on 131 and 151 (step S22). Since the servo patterns 121, 141, and 161 are bipolar, the read channel 17 uses the frequency of the processing clock when performing amplification processing or the like on the reproduction signal read from the preamble section 111a and the servo synchronization signal section 111b. Is switched twice and the gain is switched to half. In this way, bipolar processing is performed on all servo patterns 111, 121, 131, 141, 151 and 161.

  In the example illustrated in FIG. 9, the servo control unit 21 performs the following control using every other servo signal read from each servo pattern. The servo control may be performed every two or three and the following control may be performed twice or three times.

  Next, the bipolar processing performed by the bipolar unit 22 for each servo pattern will be described. When the bipolar unit 22 performs bipolar processing on each servo pattern, the bipolar unit 22 generates a timing clock signal that is synchronized with the reproduction signal read from the sync mark unit 111e, and performs bipolar processing based on the timing clock signal. I do.

  This will be specifically described with reference to FIG. FIG. 10 is a diagram for explaining the bipolar processing by the bipolar unit 22 shown in FIG. As shown in FIG. 10, the bipolar unit 22 synchronizes the predetermined timing clock signal with the reproduction signal read from the sync mark unit 111e. As described above, since the length of the side in the circumferential direction of the magnetic body arranged in the sync mark portion 111e is equal to the distance between the magnetic bodies, the peak length of the reproduction signal read from the sync mark portion 111e is It corresponds to the distance between magnetic bodies. Based on the timing clock signal, the bipolar unit 22 applies a magnetic field to the magnetic bodies forming the preamble unit 111a and the servo synchronization signal unit 111b so that every other magnet is magnetized.

  As described above, since the servo pattern 100 is generated by being mastered by an electron beam drawing apparatus or the like and cutting the magnetic material, the arrangement pattern of the magnetic material is extremely high accuracy. For this reason, the timing clock signal synchronized with the reproduction signal read from the sync mark portion 111e is a signal having substantially the same phase as the arrangement pattern of the magnetic material forming the servo pattern 100. Therefore, the bipolar unit 22 can magnetize the target magnetic body to the negative electrode with high accuracy by performing the bipolar processing based on the timing clock signal. In this way, the bipolar unit 22 magnetizes the preamble part 111a and the servo synchronization signal part 111b of the servo pattern 100 to both polarities.

  Next, the procedure of bipolar servo pattern generation processing by the magnetic recording apparatus 1 shown in FIG. 8 will be described. FIG. 11 is a flowchart showing a bipolar servo pattern generation processing procedure by the magnetic recording apparatus 1.

  As shown in FIG. 11, when an instruction to start bipolar processing is received from a host computer or the like (Yes in step S101), the bipolar unit 22 of the magnetic recording apparatus 1 An instruction is given to perform following control using some servo signals intermittently among the servo signals read from the servo areas 110 to 160 (step S102). For example, the bipolar unit 22 instructs the servo control unit 21 to perform the following control using the servo signals read from the servo areas 110, 130, and 150.

  While the following control is performed by the servo control unit 21, the bipolar unit 22 performs a bipolar process on the servo areas 110 to 160 that are not used for the following control (step S103). In the case of the above example, the bipolar unit 22 performs bipolar processing on the servo areas 120, 140, and 160 that were not used for the following control.

  Subsequently, the bipolar unit 22 instructs the servo control unit 21 to perform the following control using a servo signal that has not been used previously among the servo signals read from the servo areas 110 to 160 ( Step S104). In the case of the above example, the bipolar unit 22 instructs the servo control unit 21 to perform the following control using the servo signals read from the servo areas 120, 140, and 160, for example.

  While the following control is performed by the servo control unit 21, the bipolar unit 22 performs a bipolar process on the servo areas 110 to 160 that are not used for the following control (step S105). In the case of the above example, the bipolar unit 22 performs bipolar processing on the servo areas 110, 130, and 150 that are not used for the following control.

  Next, a procedure of bipolar processing by the bipolar unit 22 shown in FIG. 8 will be described. FIG. 12 is a flowchart showing a bipolar processing procedure by the bipolar unit 22 shown in FIG. As shown in FIG. 12, when performing bipolar processing on each servo pattern, the bipolar unit 22 first synchronizes the timing clock signal with the reproduction signal read from the sync mark unit 111e (step S201).

  Subsequently, the bipolar unit 22 initializes the value of a predetermined counter to “0” (step S202). Subsequently, the bipolar unit 22 detects the timing clock signal (step S203), and magnetizes the magnetic material to the head 13 when the timing clock signal is output from a predetermined circuit (Yes in step S204). Instruct to invert. The head 13 that has received such an instruction applies a magnetic field to the opposing magnetic body to reverse the magnetization of the magnetic body (step S205).

  Subsequently, the bipolar unit 22 adds “1” to the counter value (step S206). When the value of the counter reaches a predetermined value (Yes at Step S207), the bipolar unit 22 ends the bipolar process. On the other hand, when the value of the counter does not reach the predetermined value (No at Step S207), the bipolar unit 22 repeatedly performs the processing procedure at Steps S203 to S206. The predetermined value here refers to a value obtained by dividing 2 by the number of magnetic bodies forming the preamble portion 111a and the servo synchronization signal portion 111b.

  In this way, the magnetic recording apparatus 1 performs bipolar processing on the magnetic recording medium 10. As described above, the preamble portion 111a and the servo synchronization signal portion 111b that are bipolar processing targets are formed of a magnetic material and a non-magnetic material that are connected from the center side of the magnetic recording medium 10 to the outside. Therefore, the magnetic recording apparatus 1 only needs to perform bipolar processing only on predetermined servo sectors in the servo areas 110 to 160.

  The bipolar servo pattern generation process by the magnetic recording apparatus 1 is preferably performed during the inspection process of the head 13. In general, after the magnetic recording medium 10 is mounted on the magnetic recording apparatus 1, an accuracy inspection of the head 13 positioning control is performed in the head 13 inspection process. Since the bipolar processing can be executed when the head 13 is positioned and controlled, the magnetic recording medium 10 according to the present embodiment can be manufactured simply by adding a process for performing the bipolar processing to the conventional inspection process. can do.

  Next, the procedure of servo signal reading processing by the magnetic recording apparatus 1 will be described. FIG. 13 is a flowchart showing a servo signal read processing procedure by the magnetic recording apparatus 1. As shown in FIG. 13, when a servo signal is read from the magnetic recording medium 10, the servo control unit 21 of the magnetic recording apparatus 1 controls the positioning of the head 13 at a predetermined location on the magnetic recording medium 10 (step S301). Subsequently, the head 13 reads a reproduction signal (recording / reproduction signal and servo signal) from the magnetic recording medium 10 while maintaining a state slightly lifted from the surface of the magnetic recording medium 10 (step S302).

  Subsequently, the preamplifier 16 preamplifies the weak reproduction signal read by the head 13 and outputs it to the read channel 17 (step S303). The read channel 17 performs amplification processing, AD conversion processing, demodulation processing, and the like on the reproduction signal input from the preamplifier 16 based on a predetermined processing clock and gain (step S304).

  Subsequently, when the read channel 17 recognizes the reproduction signal read from the sync mark unit 111e from the reproduction signal input from the preamplifier 16 (Yes in step S305), the read channel 17 switches the frequency of the processing clock to twice. (Step S306), the gain is switched to half (step S307). Then, the read channel 17 performs amplification processing, AD conversion processing, demodulation processing, and the like on the reproduction signal read from the address unit 111c and the amplitude burst unit 111d based on the switched processing clock and gain ( Step S308).

  Subsequently, when the amplification processing or the like is completed for the amplitude burst unit 111d (Yes at Step S309), the read channel 17 switches the frequency of the processing clock to half (Step S310) and switches the gain to twice (Step S310). S311). That is, the read channel 17 returns the processing clock and gain to the processing clock and gain when the amplification processing or the like is performed in step S304.

  Then, the read channel 17 next amplifies the reproduction signal based on the processing clock and gain switched in the above steps S310 and 311 until the reproduction signal read from the sync mark unit 111e is recognized. Is performed (step S304). In this way, the servo control unit 21 performs positioning control and following control based on the read servo signal.

  As described above, in the magnetic recording medium 10 according to the present embodiment, the preamble portion 111a and the servo synchronization signal portion 111b of the servo pattern 100 have the magnetic material magnetized in the positive electrode and the magnetic material magnetized in the negative electrode. Are alternately arranged, so that the magnetization direction of each magnetic material forming the preamble portion 111a and the servo synchronization signal portion 111b can be stabilized.

  In the above-described embodiment, an example in which the preamble portion 111a and the servo synchronization signal portion 111b are bipolar is shown, but other portions may be bipolar. For example, all portions forming the servo pattern 100 may be bipolar. In such a case, the read channel 17 does not need to switch the frequency and gain of the processing clock when performing amplification processing or the like on the servo pattern. Further, as shown in FIG. 14, the preamble section 111a, the servo synchronization signal section 111b, and the amplitude burst section 111d may be bipolar. Thus, as the number of bipolar portions increases, the magnetization direction of the magnetic body forming the servo pattern 100 can be stabilized.

  Further, even for a servo pattern in which the burst portion is not an amplitude burst portion but a phase burst portion, the phase burst portion can be bipolar. FIG. 15 is a diagram illustrating an example of a servo pattern having a phase burst portion. In the example shown in FIG. 15, the magnetic bodies forming the preamble part 111a, the servo synchronization signal part 111b, and the phase burst part 111f are alternately magnetized in the positive electrode and the negative electrode. As a result, even if the burst portion is a servo pattern formed by a phase burst portion, the region in which the magnetization direction of the magnetic material is stabilized increases, and the magnetization direction of the magnetic material forming the servo pattern can be further stabilized. it can. When the address unit 111c, the amplitude burst unit 111d, the phase burst unit, etc. are bipolar, the bipolar unit 22 performs bipolar processing for each servo sector. This is because the address part 111c, the amplitude burst part 111d, the phase burst part 111f, and the like are not connected in the radial direction in the shape of each magnetic material.

  In the above embodiment, the magnetic recording apparatus 1 performs the bipolar processing. However, an STW having the same function as the MPU 20 shown in FIG. 8 may perform the bipolar processing. In such a case, the STW having the MPU 20 cuts the magnetic material in the servo area into a predetermined pattern, applies a magnetic field uniformly to the remaining magnetic material, and then performs bipolar processing. Alternatively, the STW having the MPU 20 cuts the magnetic material in the servo area into a predetermined pattern, uniformly applies a magnetic field to the remaining magnetic material, and then the magnetic recording device 1 on which the magnetic recording medium 10 is mounted. Is instructed to perform bipolar processing.

  In the above embodiment, since it is assumed that the shape of the servo areas 110 to 160 does not coincide with the rotation trajectory of the head 13, the bipolar unit 22 performs following control on the servo control unit 21. The instruction example has been described. This is because when the shape of the servo areas 110 to 160 does not coincide with the rotation trajectory of the head 13, a speed error of the head 13 occurs and the writing position is shifted, so that it is necessary to perform following control. However, when the shape of the servo areas 110 to 160 is formed so as to substantially coincide with the rotation trajectory of the head 13, the bipolar unit 22 instructs the servo control unit 21 to perform the following control. And bipolar processing can be performed. This eliminates the need for the bipolarization unit 22 to perform the bipolarization processing in a plurality of times by intermittently using the servo signal, so the bipolarization processing is performed on all the servo areas 110 to 160 at a time. It can be carried out. In such a case, for example, after the push pin type STW device positions the head 13 on an arbitrary track, the bipolar processing can be performed.

  Further, the processing procedures, control procedures, specific names, information including various data and parameters shown in the above-mentioned documents and drawings can be arbitrarily changed unless otherwise specified. Further, each component of each illustrated apparatus is functionally conceptual, and does not necessarily need to be physically configured as illustrated. That is, the specific form of distribution and integration of each device is not limited to the one shown in the figure, and all or a part thereof is functionally or physically distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. Further, all or any part of each processing function performed in each device may be realized by a CPU and a program analyzed and executed by the CPU, or may be realized as hardware by wired logic.

  The following additional notes are further disclosed with respect to the embodiment including the above examples.

(Supplementary note 1) A servo area that constitutes servo information is formed by an arrangement pattern of magnetic materials,
A magnetic recording medium, wherein a plurality of magnetic bodies forming the servo region are alternately magnetized in a positive electrode and a negative electrode.

(Additional remark 2) In the preamble part from which the reproduction signal for adjusting the phase of the processing clock signal used when analyzing the servo signal and the gain for amplifying the amplitude of the servo signal is read out of the servo area. The magnetic recording medium according to appendix 1, wherein the magnetic material to be formed is magnetized alternately in a positive electrode and a negative electrode.

(Additional remark 3) The magnetic recording medium of Additional remark 1 or 2 characterized by the magnetic body which forms a servo synchronizing signal part being magnetized alternately by the positive electrode and the negative electrode among the said servo area | regions.

(Additional remark 4) The magnetic body which forms the burst part from which the reproduction | regeneration signal for positioning a head to the center of a track is read among the said servo area | region is magnetized by the positive electrode and the negative electrode alternately The magnetic recording medium according to any one of appendices 1 to 3.

(Supplementary Note 5) In the plurality of magnetic bodies forming the servo region, the circumferential width is a value obtained by multiplying a distance corresponding to one period of the servo signal by a value of 0.6 to 0.9. The magnetic recording medium according to any one of appendices 1 to 4, wherein the magnetic recording medium is provided.

(Supplementary Note 6) A servo area that constitutes servo information is formed by an arrangement pattern of magnetic materials,
A magnetic recording apparatus having a magnetic recording medium, wherein a plurality of magnetic bodies forming the servo area are alternately magnetized in a positive electrode and a negative electrode.

(Supplementary note 7) A control device for controlling a magnetic recording medium manufacturing apparatus for manufacturing a magnetic recording medium having a servo area in which servo information is configured by a magnetic material arrangement pattern,
A servo control unit that performs following control for causing the head to follow a target position on the magnetic recording medium based on a servo signal read from the servo area by the head;
Bipolar processing in which the servo control unit causes the head to follow a predetermined track and causes the head to alternately magnetize a plurality of magnetic bodies forming a servo area on the track into a positive electrode and a negative electrode. A control device comprising: a bipolar unit for performing a conversion process.

(Supplementary Note 8) The bipolar unit causes the servo control unit to intermittently perform following control using a servo signal among a plurality of servo signals read from the servo area, and the following control is performed. The control apparatus according to appendix 7, wherein bipolar processing is performed on a servo area from which a servo signal other than the servo signal used in the above is read.

(Supplementary Note 9) The bipolar unit includes a reproduction signal for adjusting a phase of a processing clock signal used in analyzing the servo signal and a gain for amplifying the amplitude of the servo signal in the servo area. The control apparatus according to appendix 7 or 8, wherein bipolar processing is performed on the read preamble portion.

(Supplementary Note 10) The bipolar unit performs bipolar processing on a servo synchronization signal unit from which a reproduction signal indicating the start of an address unit for recording position information on the magnetic recording medium is read out of the servo area. The control device according to any one of appendices 7 to 9, characterized in that:

(Supplementary Note 11) The servo area has a sync mark portion for detecting a distance between magnetic bodies forming the servo area,
The control apparatus according to any one of appendices 7 to 10, wherein the bipolar unit performs a bipolar process based on the sync mark unit.

(Supplementary note 12) A magnetic recording medium manufacturing method in a magnetic recording medium manufacturing apparatus for manufacturing a magnetic recording medium in which a servo area constituting servo information is formed by a magnetic material arrangement pattern,
The magnetic recording medium manufacturing apparatus comprises:
A servo control step for performing following control for causing the head to follow a target position on the magnetic recording medium based on a servo signal read from the servo area by the head;
Bipolar processing that causes the head to follow a predetermined track with respect to the servo control step and causes the head to alternately magnetize a plurality of magnetic bodies forming a servo area on the track into a positive electrode and a negative electrode A magnetic recording medium manufacturing method comprising:

It is a figure which shows the structure of a magnetic recording device. It is a figure which shows an example of the servo pattern which the conventional magnetic recording medium has. It is a figure which shows sectional drawing of the AA line shown to FIGS. 2-1. It is a figure which shows an example of the servo pattern which the magnetic recording medium based on a present Example has. It is a figure which shows sectional drawing of the BB line shown to FIGS. It is a flowchart which shows the manufacture procedure of the magnetic-recording medium based on a present Example. It is a figure for demonstrating the relationship between the distance between magnetic bodies, and the length of the side of the circumferential direction of a magnetic body. It is a figure which shows the waveform of a servo signal in case Duty ratio is 0.2. It is a figure which shows the waveform of a servo signal in case Duty ratio is 0.5. It is a figure which shows the waveform of a servo signal in case Duty ratio is 0.8. It is a figure which shows distribution of SNR corresponding to Duty ratio and inclination coefficient kp. It is a figure which shows the function structure of a magnetic-recording apparatus. It is a figure which shows an example of the bipolarization process performed with respect to the magnetic recording medium shown in FIG. It is a figure for demonstrating the bipolarization process by the bipolarization part shown in FIG. It is a flowchart which shows the bipolar servo pattern generation processing procedure by a magnetic-recording apparatus. It is a flowchart which shows the bipolarization process sequence by the bipolarization part shown in FIG. It is a flowchart which shows the servo signal read-out processing procedure by a magnetic recording device. It is a figure which shows the other example of the servo pattern which the magnetic recording medium based on a present Example has. It is a figure which shows an example of the servo pattern which has a phase burst part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic recording device 10 Magnetic recording medium 11 Spindle motor 12 Arm 13 Head 14 VCM
15 axis 16 preamplifier 17 read channel 18 HD controller 19 power controller 20 MPU
21 Servo control unit 22 Bipolarization unit 90 Magnetic recording medium 100, 900 Servo pattern 110-160 Servo area 111, 121, 131, 141, 151, 161 Servo pattern 111a, 911a Preamble unit 111b, 911b Servo synchronization signal unit 111c, 911c Address part 111d, 911d Amplitude burst part 111e Sync mark part 111f Phase burst part 911 Servo pattern

Claims (8)

Servo area that constitutes servo information is formed by magnetic material arrangement pattern,
A magnetic recording medium, wherein a plurality of magnetic bodies forming the servo region are alternately magnetized in a positive electrode and a negative electrode.   In the servo area, a magnetic body to be formed in a preamble portion from which a reproduction signal for adjusting a phase of a processing clock signal used for analyzing a servo signal and a gain for amplifying the amplitude of the servo signal is read out The magnetic recording medium according to claim 1, wherein the positive and negative electrodes are alternately magnetized.   3. The magnetic recording medium according to claim 1, wherein a magnetic material forming a servo synchronization signal portion is magnetized alternately in a positive electrode and a negative electrode in the servo area.   In the plurality of magnetic bodies forming the servo region, the circumferential width is a value obtained by multiplying a distance corresponding to one period of the servo signal by a value of 0.6 to 0.9. The magnetic recording medium according to claim 1. Servo area that constitutes servo information is formed by magnetic material arrangement pattern,
A magnetic recording apparatus having a magnetic recording medium, wherein a plurality of magnetic bodies forming the servo area are alternately magnetized in a positive electrode and a negative electrode. A control device for controlling a magnetic recording medium manufacturing apparatus that manufactures a magnetic recording medium having a servo area in which servo information is configured by a magnetic material arrangement pattern,
A servo control unit that performs following control for causing the head to follow a target position on the magnetic recording medium based on a servo signal read from the servo area by the head;
Bipolar processing in which the servo control unit causes the head to follow a predetermined track and causes the head to alternately magnetize a plurality of magnetic bodies forming a servo area on the track into a positive electrode and a negative electrode. A control device comprising: a bipolar unit for performing a conversion process.   The bipolar unit causes the servo control unit to perform a follow control intermittently using a servo signal among a plurality of servo signals read from the servo area, and the servo used for the follow control The control apparatus according to claim 6, wherein bipolar processing is performed on a servo area from which servo signals other than signals are read. A magnetic recording medium manufacturing method in a magnetic recording medium manufacturing apparatus for manufacturing a magnetic recording medium on which a servo area comprising servo information is formed by an arrangement pattern of magnetic materials,
The magnetic recording medium manufacturing apparatus comprises:
A servo control step for performing following control for causing the head to follow a target position on the magnetic recording medium based on a servo signal read from the servo area by the head;
Bipolar processing that causes the head to follow a predetermined track with respect to the servo control step and causes the head to alternately magnetize a plurality of magnetic bodies forming a servo area on the track into a positive electrode and a negative electrode A magnetic recording medium manufacturing method comprising:

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