JP2005092988A - Hybrid magnetic recording apparatus and recording / reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent device failure by avoiding effect on information reproducing due to characteristics deterioration in a magnetic head resulting from heating during recording in a hybrid type magnetic recording device and a recording reproducing method. <P>SOLUTION: In the hybrid type magnetic recording device and the recording reproducing method, the initial value for the reproducing signal from a designated reference signal pattern, arranged on the information recording medium, is compared with the reproducing signal from the reference signal pattern afterward. When output for the reproducing signal from the reference signal pattern after the initialization goes down below a designated value corresponding to its initial value, the magnetic head is decided to be deteriorated and a recording process to the magnetic recording medium is prohibited. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention locally heats an information recording medium, records magnetic information on that portion with a magnetic head, and reproduces magnetic information recorded on the information recording medium by detecting a leakage magnetic field from a recording mark. The present invention relates to a hybrid magnetic recording apparatus and a recording / reproducing method.

  As a computer external storage device for recording and storing a large amount of information, a magnetic recording device (hard disk) is generally used. However, with the development of the information society, a hard disk capable of recording at higher density is required. It has been. Furthermore, in recent years, hard disks have been incorporated into information digital home appliances, and hard disks for such applications handle not only text data but also a large amount of image information and acoustic information.

  In order to increase the recording density of the hard disk, it is necessary to reduce the size of the recording marks recorded on the magnetic recording medium. For this purpose, the magnetic particles forming the recording layer of the magnetic recording medium must be made fine. However, miniaturization of magnetic particles causes a problem of thermal instability of recording magnetization due to thermal disturbance. This thermal disturbance of the recording magnetization can be prevented by using a magnetic material having a large magnetic anisotropy for the magnetic recording layer. However, if the magnetic recording layer is formed of a magnetic material having a large magnetic anisotropy, the coercive force of the magnetic recording layer increases in proportion to the magnitude of the magnetic anisotropy, so that the magnetic head cannot perform sufficient recording. The problem arises. As one method for solving these problems, a hybrid magnetic recording method has been proposed.

  The hybrid magnetic recording system is a method in which a predetermined portion of a magnetic recording medium having a high coercive force is locally heated, and the predetermined portion is heated to a temperature near the Curie temperature, thereby reducing the coercivity of the predetermined portion of the magnetic recording medium. This is a technique for writing information by applying a magnetic field with a magnetic head to a predetermined portion where the coercive force is lowered. Therefore, when the hybrid magnetic recording method is used, information can be easily recorded on a magnetic recording medium having a high coercive force with a relatively small magnetic field. A recording medium is obtained.

  Magnetic information recorded as a recording mark on a hybrid magnetic recording type magnetic recording medium is a reproducing magnetic head using a highly sensitive magnetic flux detection sensor such as a giant magnetoresistance effect (GMR) or a tunnel magnetoresistance effect (TMR). Can be played. In such a reproducing magnetic head, information is reproduced by detecting a leakage magnetic field from a fine recording mark.

  High-sensitivity magnetic flux detection sensors such as the giant magnetoresistive effect (GMR) and tunnel magnetoresistive effect (TMR) used in the magnetic head for reproducing in the hybrid magnetic recording system are magnetic and non-magnetic materials of nanometer order or less. It has a multilayer thin film structure in which thin films are alternately stacked, and utilizes the fact that the magnetization state of the multilayer film is changed by an external magnetic field, and the electrical resistance is correspondingly changed. A reproducing magnetic head using such a magnetic flux detection sensor is susceptible to heat and has a problem in temperature resistance characteristics.

  For example, a spin valve GMR head generally has a laminated structure of antiferromagnetic thin film / first ferromagnetic thin film / nonmagnetic metal thin film / second ferromagnetic thin film. The direction of magnetization of the first ferromagnetic thin film is fixed in one direction by exchange coupling with the antiferromagnetic thin film. On the other hand, the magnetization direction of the second ferromagnetic thin film changes depending on the magnetic field applied from the outside, and is in a state parallel or antiparallel to the magnetization direction of the first ferromagnetic thin film. The electrical resistance differs depending on whether the relationship between the magnetization directions of the first ferromagnetic thin film and the second ferromagnetic thin film is parallel or antiparallel. Therefore, when a sense current is passed through the spin valve GMR head, the voltage changes depending on the relationship between the magnetization directions of the first ferromagnetic thin film and the second ferromagnetic thin film. Information is reproduced by detecting the voltage fluctuation.

  In such a spin valve type GMR head, it is reported that when the temperature rises, the exchange coupling force between the first ferromagnetic thin film and the antiferromagnetic thin film decreases, the head characteristics deteriorate, and the output of the reproduction signal decreases. (Komuro et al., “Spin valve using CrMnPt antiferromagnetic film”, Journal of Applied Magnetics Society of Japan, Vol. 22 (1998), p509). In the same report, it is also shown that the Neel temperature of the antiferromagnetic film exists in a temperature range of 150 ° C. to 350 ° C., and the exchange coupling magnetic field decreases with increasing temperature and disappears at the Neel temperature. In addition, it has been reported that in a spin valve type GMR head, when the temperature rises, the diffusion of atoms occurs at the interface of the laminated film and the characteristics deteriorate (for example, Ueda et al., “Ni0 / Co / Cu / Co / Magnetic properties and heat resistance of CoNbZr spin valves ", Journal of Japan Society of Applied Magnetics, Vol. 22 (1998) p497).

  In order to record a fine recording mark on a magnetic recording medium using a magnetic head in a recording / reproducing apparatus using a hybrid magnetic recording system, the flying height of the slider on which the magnetic head is mounted is about 10 nm from the surface of the magnetic recording medium. It is necessary to keep below. For this reason, the magnetic head is positioned in the vicinity of the heat source of the heating mechanism.

  In such a hybrid recording apparatus, when recording information on a magnetic recording medium, the recording film in the vicinity of the reproducing magnetic head using GMR, TMR, or the like is locally heated. The reproducing magnetic head is heated by the thermal convection phenomenon. Therefore, since the reproducing magnetic head is heated every time information is recorded, atomic diffusion easily occurs at the interface between the laminated films constituting the reproducing magnetic head, and the head characteristics are deteriorated. In addition, since the magnetic domain structure formed by the exchange coupling force between the first ferromagnetic thin film and the antiferromagnetic thin film changes, the rate of change in electrical resistance with respect to the external magnetic field decreases. When a constant sense current is passed through such a deteriorated reproducing magnetic head, the reproduction output signal is lowered. That is, each time recording is performed, the reproducing magnetic head is repeatedly heated, so that the characteristic of the reproducing magnetic head gradually deteriorates.

  By the way, in a conventional hard disk, a reproducing magnetic head using a magnetoresistive effect (MR) element is generally used, and the reproducing magnetic head can be activated by passing a sense current through the MR element. However, if a high-density current continues to flow in a certain direction of the MR element, a phenomenon called electromigration occurs. When electromigration occurs, microscopic corrosion occurs in the MR element, so that the element resistance value increases and the reproducing function of the reproducing magnetic head rapidly deteriorates. As the reproduction magnetic head deteriorates, there arises a problem that information cannot be reproduced. As a countermeasure against this problem, when reproducing the burst signal for the servo pattern with the reproducing magnetic head, the resistance value of the reproducing magnetic head is always monitored, and the resistance value of the reproducing magnetic head is increased beyond a certain value. If it is determined that the reproducing magnetic head has started to deteriorate, a maintenance request is issued. Then, the information of the data area managed by the reproducing magnetic head that has started to deteriorate is saved to the data area managed by another reproducing magnetic head or another drive, and the sense current of the deteriorated reproducing magnetic head is maintained during maintenance. It has been proposed to perform an abnormality process that turns off until the time is reached (see, for example, Patent Document 1).

Japanese Patent No. 3366172 (pages 3-5 and 5-7)

  The present invention has been made to solve the above-described problems of the prior art, and in the hybrid magnetic recording apparatus and the recording / reproducing method, the influence on the information reproduction due to the characteristic deterioration of the reproducing magnetic head due to the heating during recording is avoided. The purpose is to prevent device failure.

  According to the first aspect of the present invention, an information recording medium having a magnetic recording layer, a magnetic field applying unit for magnetically recording information on the information recording medium, and a part of the information recording medium are heated And a magnetic field applying unit, a driving unit for positioning the information recording medium relative to the heating unit, and a leakage magnetic field from the magnetic recording layer of the information recording medium to detect and reproduce information. A hybrid magnetic recording apparatus including a reproduction unit, a reference signal pattern detection unit for detecting a reproduction signal from a predetermined reference signal pattern provided on the information recording medium, and reproduction from the reference signal pattern A hybrid magnetic recording comprising: a control unit that determines whether or not the reproducing unit has deteriorated based on a signal, and prohibits a recording process when the reproducing unit is determined to be deteriorated Equipment is provided .

  In the hybrid magnetic recording apparatus of the present invention, it is preferable that the control unit only allows the reproduction process after the recording process is prohibited.

  In the hybrid magnetic recording apparatus of the present invention, it is preferable that the control unit has a memory for storing an initial value of a reproduction signal from the reference signal pattern. Moreover, it is preferable that the said control part judges whether the said reproduction | regeneration part deteriorated based on the reproduction signal from the said reference signal pattern for every predetermined time.

  In the hybrid magnetic recording apparatus of the present invention, it is preferable that the reference signal pattern is recorded on the magnetic recording layer. The reference signal pattern is preferably a unique signal pattern formed in advance on the information recording medium.

  The hybrid magnetic recording apparatus of the present invention includes a reference signal pattern detection unit that detects a reproduction signal of a predetermined reference signal pattern provided on an information recording medium, and a reproduction unit that deteriorates based on the reproduction signal from the reference signal pattern. And a control unit that prohibits recording processing on the information recording medium when the reproducing unit is deteriorated. The reference signal pattern provided on the information recording medium may be recorded in advance on the magnetic recording layer of the information recording medium in the initial state, for example, when the assembly of the hybrid magnetic recording apparatus is completed, or before the reference signal pattern is reproduced. Each time, a reference signal pattern may be formed on the magnetic recording layer of the information recording medium. In addition, a unique signal pattern (such as a tracking signal pattern) previously formed on the information recording medium may be used as the reference signal pattern.

  In the hybrid magnetic recording apparatus of the present invention, for example, the control unit compares the initial value of the reproduction signal from the reference signal pattern detected by the reference signal pattern detection unit with the reproduction signal from the reference signal pattern after the initial stage. . Based on the result, the control unit determines whether or not the reproduction unit has deteriorated. As a method for judging whether or not the reproduction unit has deteriorated by comparing the initial value of the reproduction signal from the reference signal pattern and the reproduction signal from the reference signal pattern after the initial stage, for example, a reference detected after the initial stage There is a method of determining that the reproduction unit has deteriorated when the reproduction signal output from the signal pattern falls below a predetermined value with respect to the initial value. However, in this method, the predetermined value for determining the deterioration of the reproduction unit is a range in a state where the reproduction unit can still perform reproduction processing, that is, the S / N (signal-to-noise ratio) from the reproduction unit is It is set to be within the allowable range of normal operation. Further, the comparison between the reproduction signal from the reference signal pattern after the initial stage and its initial value may be performed periodically or as necessary.

  In the hybrid type magnetic recording apparatus of the present invention, the initial value of the reproduction signal from the reference signal pattern is set in advance when the reproduction unit is operating normally, for example, when the assembly of the hybrid type magnetic recording apparatus is completed. It is preferable that the reproduction signal output from is detected by the reference signal pattern detection unit and the initial value is stored in the memory of the control unit.

  If the control unit determines that the reproduction unit has deteriorated, the control unit prohibits the recording process of information on the information recording medium. If the recording operation is prohibited, the reproducing unit is not heated thereafter, so that the progress of deterioration of the reproducing unit can be suppressed. However, even if it is determined that the reproduction unit has deteriorated, since the S / N from the reproduction unit is within the allowable range of normal operation of the reproduction unit, it is possible to reproduce data already recorded on the information recording medium. is there. Therefore, after the recording process on the information recording medium is prohibited, the hybrid magnetic recording device may be used as a read-only device.

  That is, in the hybrid type magnetic recording apparatus of the present invention, even if the reproduction unit deteriorates due to heating during information recording, the deterioration state of the reproduction unit is monitored by the control unit based on the reproduction signal output from the reference signal pattern. As a result, the recording process can be prohibited before the reproduction unit cannot reproduce the information. Therefore, it is possible to prevent the reproduction unit from being deteriorated due to the influence of heating at the time of recording and to prevent information reproduction, and to prevent a device failure.

  The hybrid magnetic recording device of the present invention further includes an interface unit for connecting the hybrid magnetic recording device to an external magnetic recording device, and the control unit stores information on the data area of the information recording medium, It is preferable to move to the external magnetic recording device via the interface unit.

  When the hybrid magnetic recording device can be connected to an external magnetic recording device via an interface, the information in the data area of the information recording medium is stored in the hybrid magnetic recording device after it is determined that the reproducing unit has deteriorated. The control unit may retreat to an external magnetic recording device via an interface, and a new data area may be secured there to continue recording and reproducing information. By configuring such a system, even if an abnormality occurs in the reproducing unit of the hybrid magnetic recording apparatus, the hybrid magnetic recording apparatus or a system using the same can be continuously used without stopping. .

  The hybrid magnetic recording device of the present invention further includes two or more combinations of the information recording medium and a reproducing unit for reproducing the information recording medium, and the control unit has deteriorated the reproducing. It is preferable to move the information in the data area of the information recording medium combined with the recording section to the data area of the information recording medium combined with the reproducing section that has not deteriorated.

  When the hybrid magnetic recording apparatus of the present invention includes two or more combinations of an information recording medium and a reproducing unit that reproduces the information recording medium, the information in the data area of the information recording medium combined with the deteriorated reproducing unit is used as the hybrid magnetic The control unit in the recording apparatus may be saved in the data area of the information recording medium combined with the reproducing unit that has not deteriorated, and a new data area may be secured there to continue recording and reproducing information.

  The hybrid type magnetic recording apparatus of the present invention further includes a warning display unit in the hybrid type magnetic recording apparatus, and the warning display unit displays a warning when it is determined that the reproducing unit is deteriorated. It is preferable.

  In the hybrid magnetic recording apparatus of the present invention, the reproducing unit includes a reproducing sensor that detects a leakage magnetic field from the magnetic recording layer, and the reproducing sensor has a multilayer film structure in which a plurality of magnetic thin films and a nonmagnetic thin film are stacked. It is preferable that information reproduction is performed utilizing the fact that the resistance of the multilayer film is changed by the leakage magnetic field. That is, it is preferable to use a high-sensitivity magnetic flux detection sensor such as GMR or TMR for the reproducing sensor of the reproducing unit of the hybrid magnetic recording apparatus of the present invention.

  In the hybrid magnetic recording apparatus of the present invention, it is preferable that the magnetic field applying unit and the reproducing unit are an integrated composite head.

  According to the second aspect of the present invention, a predetermined portion of the information recording medium is heated, a magnetic field is applied to the heated predetermined portion, information is recorded, and from the recorded predetermined portion And reproducing information by detecting a leakage magnetic field with a reproduction sensor, and further, an initial value of a reproduction signal from a predetermined reference signal pattern provided on the information recording medium Is detected by the reproduction sensor, the reproduction signal from the reference signal pattern after the initial is detected by the reproduction sensor, the initial value of the reproduction signal from the reference signal pattern, and the reference signal pattern after the initial And a reproduction signal of the recording medium to determine whether or not the reproduction sensor is deteriorated, and when the reproduction sensor is determined to be deteriorated, recording on the information recording medium is prohibited. Do Recording and playback method is provided.

  The recording / reproducing method of the present invention preferably further includes storing an initial value of a reproduction signal from the reference signal pattern.

  The recording / reproducing method of the present invention preferably further includes enabling only the reproducing process after prohibiting the recording process on the information recording medium. Further, it is preferable that the deterioration of the regeneration sensor is determined every predetermined time.

  The recording / reproducing method of the present invention preferably further includes moving the information in the data area of the information recording medium to an external recording device via the interface.

  The recording / reproducing method of the present invention further includes two or more combinations of the information recording medium and a reproduction sensor for reproducing the information recording medium, and the data area of the information recording medium combined with the deteriorated reproduction sensor. Preferably, the method includes moving information to a data area of the information recording medium combined with the reproduction sensor that has not deteriorated.

  In the recording / reproducing method of the present invention, first, an initial value of a reproduction signal from a predetermined reference signal pattern provided on an information recording medium is detected by a reproduction sensor. At this time, it is preferable to store the initial value in a memory such as a control unit in the hybrid magnetic recording apparatus. Next, the reproduction signal from the reference signal pattern after the initial stage is detected by the reproduction sensor. Next, the reproduction signal from the reference signal pattern after the initial stage is compared with the initial value of the reproduction signal from the reference signal pattern. Then, for example, when the reproduction signal output from the reference signal pattern detected after the initial stage falls below a predetermined value with respect to the initial value, it is determined that the reproduction sensor has deteriorated and recording processing on the information recording medium is performed. Is prohibited. At this time, the predetermined value used for determining the deterioration of the regeneration sensor is within a range where the regeneration sensor can still perform the regeneration process, that is, the S / N from the regeneration sensor is within an allowable range of normal operation of the regeneration sensor. Is set as follows. After it is determined that the reproduction sensor has deteriorated and recording processing on the information recording medium is prohibited, it is preferable to use the hybrid magnetic recording apparatus as a reproduction-only apparatus.

  If the hybrid magnetic recording device can be connected to an external magnetic recording device via an interface or the like, after the recording process on the information recording medium is prohibited, the information in the data area of the information recording medium is transferred to the interface. The information may be evacuated to an external recording device, and a new data area may be secured there to continue recording and reproducing information. Further, when the hybrid magnetic recording apparatus includes two or more combinations of the reproduction sensor and the information recording medium, it is judged that the reproduction sensor has deteriorated and the recording process on the information recording medium is prohibited, and then the deterioration has occurred. Information in the data area of the information recording medium combined with the reproduction sensor is saved in the data area of the information recording medium combined with the non-degraded reproduction sensor, and a new data area is secured there to record and reproduce information. May be continued.

  The recording / reproducing method of the present invention preferably further includes displaying a warning when it is determined that the reproduction sensor is deteriorated.

  The recording / reproducing method of the present invention preferably further includes recording the reference signal pattern on the magnetic recording layer before detecting the initial value of the reproduced signal.

  In the recording / reproducing method of the present invention, it is preferable to use a signal pattern previously formed on the information recording medium as the unique signal pattern as the reference signal pattern.

  In the recording / reproducing method of the present invention, the reproducing sensor has a multilayer structure in which a plurality of magnetic thin films and a nonmagnetic thin film are laminated, and the resistance of the multilayer film is changed by the leakage magnetic field. It is preferable to reproduce information.

  According to the hybrid type magnetic recording apparatus and the recording / reproducing method of the present invention, even if the reproduction sensor deteriorates due to heating during information recording, it is based on the reproduction signal output from a predetermined reference signal pattern formed on the information recording medium. Since the deterioration of the reproduction sensor is determined, the recording process can be prohibited before the reproduction sensor cannot reproduce. Therefore, it is possible to prevent the reproduction sensor from being deteriorated due to the influence of heating at the time of recording and to prevent information reproduction, and to prevent a device failure.

  Examples of the present invention will be described below in detail with reference to the drawings, but the present invention is not limited thereto.

[Hybrid magnetic recording device]
A configuration diagram of the hybrid type magnetic recording apparatus of the present embodiment is shown in FIG. As shown in FIG. 1, the hybrid magnetic recording apparatus 1 of this example includes a magnetic recording medium 2, a GMR composite magnetic head 3, a magnetic head position adjusting mechanism section 4, a laser head 5, a laser head position adjusting mechanism section 6, and a motor 7. , Recording / reproduction processing unit 8, laser light control unit 9, reference signal abnormality detection unit 10, control unit 11, interface 12, magnetic head position adjustment control unit 13, laser head position adjustment control unit 14, warning indicator 15, and recording signal The input unit 16 is configured. Note that a reference signal pattern for monitoring the deterioration state of the GMR composite magnetic head 3 is formed on the magnetic recording medium 2.

  As shown in FIG. 1, a magnetic field is applied to the recording film surface side 2a of the magnetic recording medium 2 and a leakage magnetic field is detected from a recording mark formed on the recording film of the magnetic recording medium 2 during information recording. A composite magnetic head 3 is disposed, and a laser head 5 for locally heating a predetermined position of the magnetic recording medium 2 during information recording is disposed on the opposite side 2b.

  A laser head 5 for locally heating a predetermined position of the magnetic recording medium 2 is mechanically supported by a laser head position adjusting mechanism 6 as shown in FIG. The laser head position adjustment mechanism 6 is connected to the laser head position adjustment controller 14. The laser head 5 is moved to a predetermined radial position on the magnetic recording medium 2 by the laser head position adjustment mechanism 6 controlled by the laser head position adjustment controller 14. The laser head 5 is connected to a laser light control unit 9, and laser light emission is controlled by the laser light control unit 9. In this example, a semiconductor laser having a wavelength of 650 nm is used for the laser head 5. In addition, the lens system mounted in the laser head 5 was adjusted to focus the laser spot near the recording film surface of the magnetic recording medium 2. The laser beam power was fixed at 15 mW.

  As shown in FIG. 1, the GMR composite magnetic head 3 includes a recording / reproducing processor 8 for recording / reproducing information and a reference for detecting a reproduction signal from a reference signal pattern formed on the magnetic recording medium 2. The signal abnormality detection unit 10 is connected. Further, as shown in FIG. 1, the GMR composite magnetic head 3 is mechanically supported by a magnetic head position adjustment mechanism unit 4, and the magnetic head position adjustment mechanism unit 4 is connected to a magnetic head position adjustment control unit 13. Has been. The GMR composite magnetic head 3 is moved to a predetermined radial position on the magnetic recording medium 2 by the magnetic head position adjustment mechanism unit 4 controlled by the magnetic head position adjustment control unit 13.

  The GMR composite magnetic head 3 in this example is a composite head configured by using an inductive thin film head having a track width of 0.29 μm as a recording head and a spin valve type GMR head having a track width of 0.2 μm as a reproducing head. . With this GMR composite magnetic head 3, a flying height of about 10 nm was obtained at a disk rotational speed of 5400 rpm. The recording current passed through the inductive thin film head was 30 mA, and the sense current passed through the spin valve GMR head was 3.5 mA.

  As shown in FIG. 1, the recording / reproduction processing unit 8, the magnetic head position adjustment control unit 13, and the laser head position adjustment control unit 14 are connected to the control unit 11 and operate in cooperation with each other via the control unit 11. It is controlled. Further, the control unit 11 controls the entire apparatus by linking the components in the hybrid magnetic recording apparatus 1. Further, the GMR composite magnetic head 3 and the laser head 5 are focused so that the spot of the laser light emitted from the laser head 5 is focused in the vicinity of the medium portion immediately below the magnetic pole position of the inductive thin film head in the GMR composite magnetic head 3. And the GMR composite magnetic head 3 and the laser head 5 are adjusted by the control unit 11 so as to move to a target position on the medium while maintaining this positional relationship. During the recording operation, in conjunction with the supply of the recording current from the recording / reproducing processor 8 to the GMR composite magnetic head 3, a laser beam is emitted to irradiate a predetermined position of the magnetic recording medium 2, and the predetermined position is locally Heat up.

  Further, the reference signal abnormality detection unit 10 and the warning indicator 15 are connected to the control unit 11 as shown in FIG. A reproduction signal from a reference signal pattern, which will be described later, detected by the reference signal abnormality detection unit 10 is sent to the control unit 11, and the control unit 11 determines deterioration of the GMR composite magnetic head 3. When the controller 11 determines that the GMR composite magnetic head 3 has deteriorated, a warning to that effect is displayed as an error message on the warning display 15.

  Further, as shown in FIG. 1, the control unit 11 and the recording / reproducing processing unit 8 are connected to an external device, for example, an external hybrid magnetic recording device, a storage device such as a conventional hard disk device, a computer, or the like via an interface 12. It is connected. Data input / output between the recording / playback processing unit 8 and the external device is performed via the interface 12. Further, as shown in FIG. 1, the recording / reproducing processor 8 is connected to a recording signal input unit 16, and information to be recorded on the magnetic recording medium 2 is recorded from the recording signal input unit 16 at the time of information recording. The data is input to the reproduction processing unit 8. The recording information input operation from the recording signal input unit 16 to the recording / playback processing unit 8 is controlled by the control unit 11.

  As shown in FIG. 1, the magnetic recording medium 2 is attached to a spindle of a motor 7 and rotated at a predetermined rotational speed. The motor 7 is connected to the control unit 11, and the rotation speed and the like are controlled by the control unit 11.

[Magnetic recording medium]
A schematic cross-sectional view of the magnetic recording medium 2 produced in this example is shown in FIG. As shown in FIG. 2, the magnetic recording medium 2 has a structure in which a Cr base film 22, a Pt base film 23, a Co / Pt artificial lattice magnetic recording film 24, and a protective film 25 are sequentially stacked on a substrate 21.

Here, a method for manufacturing the magnetic recording medium 2 manufactured in this example will be described. First, as the substrate 21, a glass substrate for 2.5 inch magnetic disk was prepared, and the substrate 21 was cleaned. Next, the substrate 21 was placed in a sputtering film forming apparatus (not shown), and was evacuated to a degree of vacuum of less than 1 × 10 ⁻⁷ Torr in advance in the introduction chamber. Thereafter, Ar gas was introduced into the sputtering film forming apparatus as a sputtering gas.

  Next, Cr was formed to a thickness of 10 nm on the substrate 21 as a Cr underlayer 22 by DC magnetron sputtering. At this time, the Cr underlayer 22 was formed under the conditions of Ar gas pressure of 2 mTorr and the applied power of the Cr target of 1 kW. Next, Pt was formed to a thickness of 20 nm on the Cr underlayer 22 as a Pt underlayer 23 by DC magnetron sputtering. At this time, the Pt underlayer 23 was formed under the conditions of Ar gas pressure of 10 mTorr and Pt target applied power of 1 kW.

  Further, a Co / Pt artificial lattice magnetic recording film 24 was formed on the Pt underlayer 23 by a DC magnetron sputtering method. The Co / Pt artificial lattice magnetic recording film 24 was formed by alternately laminating a Co layer having a thickness of 0.4 nm and a Pt layer having a thickness of 0.8 nm for 12 periods. At this time, the Co / Pt artificial lattice magnetic recording film 24 was formed under the conditions of Ar gas pressure of 10 mTorr, Pt, and Co target applied power of 100 W.

  Finally, C was formed to a thickness of 5 nm as a protective film 25 on the Co / Pt artificial lattice magnetic recording film 24 by DC magnetron sputtering. At this time, the protective film 25 was formed under the conditions of an Ar gas pressure of 2 mTorr and an applied power of 1 kW of the C target. The magnetic recording medium 2 of this example was obtained by the above manufacturing method.

[Information recording / playback and playback resistance characteristics]
The magnetic recording medium 2 obtained by the above production method was subjected to a tape burnishing process and a lubricant was applied, and then set in the hybrid magnetic recording apparatus 1 shown in FIG.

In the initial state of the hybrid magnetic recording device 1 (for example, immediately after the assembly of the device), a repetitive pattern of “1” and “0” is recorded at a recording density of 50 kFCI on the magnetic recording medium 2 at a radius of 20 mm. Was used as a reference signal pattern. A reproduction signal from the reference signal pattern in the initial state is detected by the GMR composite magnetic head 3 to obtain an average output (initial value S ₀ ) and stored in the memory in the control unit 11 of the hybrid magnetic recording apparatus 1. did.

  Next, in accordance with the flowchart shown in FIG. 3, a reproduction signal from the reference signal pattern is reproduced while repeating recording and reproduction of a random pattern having a recording density of 250 kFCI to 500 kFCI in a data area other than the area where the reference signal pattern is written. Monitoring was performed by the control unit 11. In this example, the time interval Δt for monitoring the reproduction signal from the reference signal pattern (hereinafter referred to as the reproduction interval of the reference signal pattern) is 1 hour. The reproduction interval Δt of the reference signal pattern is set in advance before information recording and reproduction.

  Next, the recording / reproducing method used in this example will be described with reference to the flowchart of FIG. First, while recording / reproducing information on the magnetic recording medium 2 is being performed, an elapsed time t from the previous reproduction of the reference signal pattern is monitored by the control unit 11 (step 31). If the elapsed time t from the previous reproduction of the reference signal pattern is less than the preset reference signal pattern reproduction interval Δt, step 31 is continued.

When the elapsed time t is equal to or greater than the reproduction interval Δt of the reference signal pattern, the reproduction of the reference signal patterns is performed by the reference signal error detection unit 10, the mean values S ₁ of the reproduction output is obtained by the control unit 11 (Step 32) .

Next, the control unit 11 compares the reproduction output S ₁ from the reference signal pattern obtained in step 32 with the initial value S ₀ of the reproduction output from the reference signal pattern, and the GMR composite magnetic head 3 deteriorates. (Step 33). In this example, when the value of (S ₀ −S ₁ ) / S ₀ is larger than the critical value ΔS _LIM , it is determined that the GMR composite magnetic head 3 has deteriorated. In this example, the critical value ΔS _{LIM is set} to 10%. In this example, the critical value ΔS _LIM = 10% is set for the following reason. As will be described later (see comparative example), in the GMR composite magnetic head 3 used in this example, when the value of (S ₀ -S ₁ ) / S ₀ exceeds 10%, a reproducing head (spin valve type GMR head) ) Is accelerated, and when the value of (S ₀ −S ₁ ) / S ₀ reaches 12%, the signal with the maximum recording density cannot be reproduced. Therefore, in this example, ΔS _LIM = 10%. However, the present invention is not limited to the value of ΔS _LIM = 10%, and an optimum critical value ΔS _LIM can be arbitrarily set according to the deterioration characteristics of the head to be used.

On the other hand, if the value of (S ₀ −S ₁ ) / S ₀ is equal to or less than the critical value ΔS _LIM , it is determined that the GMR composite magnetic head 3 has not deteriorated, and the process returns to step 31. At that time, the elapsed time t from the previous reproduction of the reference signal pattern is reset (step 39).

If it is determined in step 33 that (S ₀ −S ₁ ) / S ₀ > ΔS _LIM and the GMR composite magnetic head 3 has deteriorated, an abnormality processing start command is issued (step 34), and the following Abnormal processing is performed. First, a warning display 15 displays a warning that the GMR composite magnetic head 3 has deteriorated (step 35). Warnings are displayed as error messages. At this time, if the hybrid magnetic recording apparatus 1 of this example is connected to a host system such as a computer, a warning signal may be sent to the host system such as a computer. Next, the recording process on the magnetic recording medium 2 is prohibited, and the GMR composite magnetic head 3 is dedicated to reproduction (step 36). As a method for prohibiting recording processing on the magnetic recording medium 2, for example, the control unit 11 in the hybrid magnetic recording apparatus 1 of FIG. 1 inputs recording information from the recording signal input unit 16 to the recording / playback processing unit 8. A command for prohibiting the operation is issued, and a command for prohibiting laser light irradiation other than during reproduction is issued to the laser light control unit 9. Alternatively, the control unit 11 in the hybrid magnetic recording apparatus 1 in FIG. 1 issues a command for prohibiting the recording information output operation to the GMR composite magnetic head 3 to the recording / reproducing processing unit 8 and also sends the command to the laser light control unit 9. You may issue the command which prohibits laser beam irradiation other than the time of reproduction | regeneration.

  Next, it is determined whether or not the data of the magnetic recording medium 2 whose recording is prohibited can be transferred to an external device (step 37). If transfer is impossible, the continuation of the information recording process is abandoned, and the hybrid magnetic recording apparatus 1 is dedicated to reproduction.

  When the data of the magnetic recording medium 2 that is prohibited from recording can be transferred to an external device, the data of the magnetic recording medium 2 is once reproduced by the recording / reproducing processor 8 and the reproduced data is transferred from the recording / reproducing processor 8 to the interface 12. To the data area of the external device. At this time, the control unit 11 in the hybrid magnetic recording apparatus 1 controls data transfer. The control unit 11 may directly control the external device as well as control to transfer data to the external device via the interface 12, or the hybrid magnetic recording device 1 may be connected to a host system such as a computer. If connected, data may be transferred to an external device via the interface 12 under the control of the host system. The transferred data of the magnetic recording medium 2 is recorded in a storage unit or the like of the external device, and information recording and reproduction are continued in the external device. At this time, the recording / reproduction of information continued in the data area in the external device may be controlled by the control unit 11 of the original hybrid magnetic recording device 1 or may be controlled by the control unit of the external device or the like. good.

In the hybrid magnetic recording apparatus 1 controlled according to the algorithm as shown in FIG. 3, when recording and reproduction of a random pattern are repeated, the output decrease of the reference signal pattern exceeds 10% after 215 hours from the start of the operation. , (S ₀ −S ₁ ) / S ₀ > ΔS _LIM , an error indicating the abnormality of the GMR composite magnetic head 3 was displayed, and thereafter, information recording processing on the magnetic recording medium 2 was prohibited. It was also confirmed that the random pattern information recorded on the magnetic recording medium 2 up to this point can be reproduced.

  Furthermore, in this example, the reproduction signal output from the reference signal pattern was confirmed every hour even after the above-described abnormality processing was performed. As a result, the reproduction signal output from the reference signal pattern was maintained at a substantially constant value, and no output reduction was observed. In addition, even after 240 hours from the start of the operation, the random pattern information recorded on the magnetic recording medium 2 could be reproduced.

[Comparative example]
In the comparative example, using a hybrid magnetic recording apparatus similar to that in the example, a random pattern having a maximum recording density of 500 kFCI was repeatedly recorded and reproduced, and a reproduction resistance test of the GMR composite magnetic head was conducted. However, even if the reproduction signal output from the reference signal pattern falls below 10% (ΔS _LIM = 10%) with respect to the initial value, the abnormality processing is not performed except that the abnormal processing as shown in FIG. 3 is not performed. Information was recorded and reproduced in the same procedure as in the example. As the reference signal pattern, a repeated pattern of “1” and “0” was recorded at a recording density of 50 kFCI at a position of a radius of 20 mm of the magnetic recording medium as in the example.

  As a result of the reproduction resistance test of the GMR composite magnetic head of this example, the reproduction signal output from the reference signal pattern decreased by more than 10% with respect to the initial value after 203 hours from the start of the operation. In this example, the random pattern recording and reproduction operations were continued and repeated thereafter. As a result, the amount of decrease in the reproduction signal output from the reference signal pattern with respect to the initial value of the reproduction signal output from the reference signal pattern increases with time, and the amount of decrease in the reproduction signal output from the reference signal pattern after 220 hours. Increased to 11% after 233 hours to 12%. During this time, with the passage of time, the signal output of the random pattern that continued recording and reproduction also decreased, and the S / N decreased.

  Further, 203 hours after the amount of decrease in the reproduction signal output from the reference signal pattern exceeds 10%, the S / N decrease rate of the random pattern increases and the decrease in the reproduction signal output from the reference signal pattern after 233 hours. When the amount reached 12%, the signal component of the maximum recording density (500 kFCI) could not be reproduced with sufficient S / N. That is, from this result, by performing the abnormal processing as shown in FIG. 3 at the time of recording / reproducing information as in the embodiment, the information is continuously reproduced even if the GMR composite magnetic head is slightly deteriorated by heating at the time of recording. It has been found that device failure can be prevented.

In the above embodiment, the critical value ΔS _LIM for starting the abnormal process as shown in FIG. 3 has been described as 10%, but the present invention is not limited to this. The critical value ΔS _LIM can be set to an arbitrary value based on the specifications and purpose of the hybrid magnetic recording apparatus. For example, a hybrid magnetic recording apparatus having a high-performance reproduction signal processing system can reproduce even if ΔS _LIM is greater than 10%. On the other hand, in a hybrid magnetic recording apparatus that places importance on the error rate, high reliability is required for the critical value ΔS _LIM , so ΔS _LIM must be set to a value smaller than 10%.

  In the above embodiment, the repetitive pattern of “1” and “0” at the recording density of 50 kFCI is used as the reference signal pattern, but the present invention is not limited to this. The reference signal pattern only needs to obtain a stable reproduction output, and can be formed with an arbitrary signal pattern. Further, the recording density and signal pattern of the reference signal pattern may be set according to the design of each hybrid magnetic recording apparatus. In addition, a unique signal pattern (such as a tracking signal pattern) formed in advance on the information recording medium may be used as the reference signal pattern.

  In the recording / reproducing method of the above embodiment, the value of the reproduction output signal of the reference signal pattern is read as numerical data into the control unit in the hybrid magnetic recording apparatus and processed, but the electric signal is directly processed by the electric circuit. Also good.

  In the above embodiment, the magnetic head is arranged on the recording film surface side with respect to the substrate, and the laser beam is irradiated from the opposite side to the recording film surface side. However, the laser beam is emitted from the same recording film surface side as the magnetic head. May be incident. In the above embodiment, the laser beam is irradiated onto the magnetic recording medium using the lens system, but the present invention is not limited to this. For example, the laser beam may be guided to the vicinity of a desired position via a waveguide or an optical fiber, and the laser beam may be irradiated onto the magnetic recording medium from there. Further, in the above embodiment, laser light is used as a heating source for the magnetic recording medium, but the present invention is not limited to this, and for example, any electromagnetic wave, near-field light, heater, or the like may be used.

  In the hybrid type magnetic recording apparatus of the above embodiment, as shown in FIG. 1, one magnetic head for one magnetic recording medium, that is, a combination of the magnetic recording medium and the magnetic head is one set of single-side recording. Although an example has been described, the present invention is not limited to this. A structure having a combination of two or more magnetic recording media and a magnetic head in the same apparatus, for example, two or more magnetic recording media are provided on the spindle of the motor 7 of FIG. 1, and each magnetic recording medium has a magnetic head and A structure in which a heating laser head is provided may be used. In such a hybrid type magnetic recording apparatus, data in the data area of the magnetic recording medium combined with the deteriorated magnetic head is once reproduced by the recording / reproducing processor 8 of FIG. 1, and the reproduced data is recorded / reproduced. The data is transferred from the unit 8 to the data area of the magnetic recording medium combined with the non-degraded magnetic head and recorded. Thereafter, data recording / reproduction is continued in the data area of the magnetic recording medium combined with the magnetic head which has not deteriorated. The transfer control of these data can be controlled by the control unit 11 in FIG.

  According to the hybrid type magnetic recording apparatus and the recording / reproducing method of the present invention, the deterioration of the magnetic head due to heating at the time of hybrid recording is judged based on the reproduction signal from the predetermined reference signal pattern, so that the deterioration of the magnetic head is detected quickly. In addition, recording processing on the magnetic recording medium can be prohibited while the reproducing operation of the magnetic head is possible. As a result, it is possible to prevent an apparatus failure in which reproduction cannot be performed due to deterioration of the magnetic head. Therefore, information recorded on the magnetic recording medium can be protected, and the reliability of the hybrid magnetic recording apparatus can be improved.

FIG. 1 is a schematic configuration diagram of a hybrid magnetic recording apparatus according to an embodiment. FIG. 2 is a schematic cross-sectional view of the magnetic recording medium of the example. FIG. 3 is a flowchart for explaining the abnormality process in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid type magnetic recording apparatus 2 Magnetic recording medium 3 GMR composite magnetic head 4 Magnetic head position adjustment mechanism part 5 Laser head 6 Laser head position adjustment mechanism part 7 Motor 8 Recording / reproduction processing part 9 Laser light control part 10 Reference signal abnormality detection part DESCRIPTION OF SYMBOLS 11 Control part 12 Interface 13 Magnetic head position adjustment control part 14 Laser head position adjustment control part 15 Warning indicator 16 Recording signal input part

Claims (21)

An information recording medium having a magnetic recording layer, a magnetic field applying unit for magnetically recording information on the information recording medium, a heating unit for heating a part of the information recording medium, and the magnetic field applying unit And a hybrid type magnetic recording apparatus comprising: a driving unit for positioning the information recording medium with respect to the heating unit; and a reproducing unit for detecting a leakage magnetic field from the magnetic recording layer of the information recording medium and reproducing information Because
Further, a reference signal pattern detection unit that detects a reproduction signal from a predetermined reference signal pattern provided on the information recording medium,
A control unit that determines whether or not the playback unit has deteriorated based on a playback signal from the reference signal pattern and prohibits recording processing when the playback unit is determined to have deteriorated. A hybrid type magnetic recording apparatus. The hybrid magnetic recording apparatus according to claim 1, wherein the control unit enables only a reproduction process after the recording process is prohibited. 3. The hybrid magnetic recording apparatus according to claim 1, wherein the control unit includes a memory for storing an initial value of a reproduction signal from the reference signal pattern. The said control part judges whether the said reproduction | regeneration part degraded based on the reproduction signal from the said reference signal pattern for every predetermined time, The Claim 1 characterized by the above-mentioned. Hybrid magnetic recording device. The hybrid magnetic recording apparatus according to claim 1, wherein the reference signal pattern is recorded on the magnetic recording layer. The hybrid magnetic recording apparatus according to claim 1, wherein the reference signal pattern is a unique signal pattern formed in advance on the information recording medium. Further, the hybrid magnetic recording device includes an interface unit for connecting to an external magnetic recording device, and the control unit transmits information on the data area of the information recording medium via the interface unit to the external magnetic recording device. The hybrid magnetic recording apparatus according to claim 1, wherein the hybrid magnetic recording apparatus is moved to a recording apparatus. Further, the hybrid magnetic recording apparatus includes two or more combinations of the information recording medium and a reproducing unit that reproduces the information recording medium, and the control unit combines the deteriorated reproducing unit with the data area of the information recording medium. The hybrid magnetic recording apparatus according to claim 1, wherein the information is moved to a data area of the information recording medium combined with the reproducing unit that is not deteriorated. The hybrid magnetic recording apparatus further includes a warning display unit, and when the reproduction unit is determined to be deteriorated, the warning display unit displays a warning. The hybrid magnetic recording apparatus according to any one of the above. The reproducing unit includes a reproducing sensor for detecting a leakage magnetic field from the magnetic recording layer, and the reproducing sensor has a multilayer film structure in which a plurality of magnetic thin films and a nonmagnetic thin film are stacked, and the resistance of the multilayer film is The hybrid magnetic recording apparatus according to any one of claims 1 to 9, wherein information reproduction is performed using a change caused by a leakage magnetic field. The hybrid magnetic recording apparatus according to claim 1, wherein the magnetic field applying unit and the reproducing unit are an integrated composite head. Information is recorded by heating a predetermined portion of the information recording medium, applying a magnetic field to the heated predetermined portion, and recording a leakage magnetic field from the recorded predetermined portion with a reproduction sensor. A hybrid type recording / playback method comprising:
Furthermore, detecting an initial value of a reproduction signal from a predetermined reference signal pattern provided on the information recording medium with the reproduction sensor;
Detecting the reproduction signal from the reference signal pattern after the initial stage with the reproduction sensor;
Comparing the initial value of the reproduction signal from the reference signal pattern with the reproduction signal from the reference signal pattern after the initial stage to determine deterioration of the reproduction sensor;
A recording / reproducing method comprising: prohibiting a recording process on the information recording medium when it is determined that the reproduction sensor has deteriorated. 13. The recording / reproducing method according to claim 12, further comprising storing an initial value of a reproduction signal from the reference signal pattern. 14. The recording / reproducing method according to claim 12, further comprising enabling only the reproducing process after prohibiting the recording process on the information recording medium. 15. The recording / reproducing method according to claim 12, wherein the deterioration of the reproduction sensor is determined every predetermined time. The recording / reproducing method according to any one of claims 12 to 15, further comprising: moving information in a data area of the information recording medium to an external recording device via an interface. Further, there are two or more combinations of the information recording medium and a reproduction sensor for reproducing the information recording medium, and the information on the data area of the information recording medium combined with the deteriorated reproduction sensor is not deteriorated. The recording / reproducing method according to claim 12, further comprising: moving to a data area of the information recording medium combined with the information recording medium. The recording / reproducing method according to claim 12, further comprising displaying a warning when it is determined that the reproduction sensor is deteriorated. The recording / reproducing method according to claim 12, further comprising recording the reference signal pattern on the magnetic recording layer before detecting an initial value of the reproduction signal. 20. The recording / reproducing method according to any one of claims 12 to 19, wherein a signal pattern previously formed on the information recording medium is used as a specific signal pattern as the reference signal pattern. The reproduction sensor has a multilayer structure in which a plurality of magnetic thin films and a non-magnetic thin film are laminated, and information is reproduced by utilizing the fact that the resistance of the multilayer film is changed by the leakage magnetic field. The recording / reproducing method according to any one of claims 12 to 20.

Images