JP2006048780A - Information recording device and method for positioning head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording device of a light assist recording system for performing the stable operation by more precisely concentrating laser light near a gap of the magnetic head during the information recording, and a method for positioning a head thereof. <P>SOLUTION: The information recording device for recording the information by applying the light and an external magnetic field to the information recording medium, is provided with the magnetic head for applying the external magnetic field to the information recording medium and the optical head disposed at the position facing the magnetic head so that the information recording medium is sandwiched and for irradiating the information recording medium with the light. The relative position between the optical head and the magnetic head is adjusted by irradiating the magnetic head with the irradiation light from the optical head transmitted through the information recording medium and by detecting the reflected light from the magnetic head. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information recording apparatus for recording information as a magnetic mark and a head positioning method. More specifically, the present invention records information by applying an external magnetic field while irradiating and heating a predetermined area of a recording film. The present invention relates to an information recording apparatus and a head positioning method.

  With the recent development of information networks and the spread of multimedia, magnetic disk devices, which are the main information recording devices that support them, have become important issues in increasing the capacity, miniaturization, and cost reduction of the devices.

  In a magnetic disk apparatus currently in practical use, the in-plane magnetic recording system is adopted. The in-plane magnetic recording method uses a magnetic disk provided with a magnetic film that is easily magnetized in a direction parallel to the disk surface as a recording film, and records information by forming magnetic domains having in-plane magnetization in the recording film. It is a recording method. In such an in-plane magnetic recording system, when the recording film thickness of the magnetic disk is increased, a magnetic field (so-called demagnetizing field) generated from the boundary between magnetic domains having different magnetization directions impedes the formation of minute magnetic domains. Recording becomes difficult. Therefore, in the longitudinal magnetic recording type magnetic disk, it is necessary to reduce the thickness of the recording film in order to improve the recording density.

  However, if the thickness of the recording film is very thin, thermal fluctuation of the recording magnetic domain occurs even at room temperature, and the magnetization of the recording magnetic domain decreases with time. When such a recorded magnetic domain with reduced magnetization is reproduced, there arises a problem that the reproduction output is lowered. As a method for solving this problem, a method of increasing the coercive force of the recording film can be considered. However, if the coercive force is increased, the magnetic field of the recording head is insufficient and sufficient recording cannot be performed, and a signal sufficient for data reproduction is obtained. There was no problem.

  As a method for solving these problems and achieving high density of the magnetic disk, a predetermined area is obtained while a semiconductor laser is mounted on the magnetic head and a laser beam emitted from the semiconductor laser is irradiated to the predetermined area of the magnetic disk. For example, a method of recording information by applying a magnetic field with a magnetic head (so-called optically assisted magnetic recording method) has been proposed (see, for example, JP-A-3-189905). In this recording method, by irradiating the magnetic recording medium with a laser beam, the magnetic recording medium can be locally heated, and the coercivity of the heated region can be temporarily reduced. Therefore, information can be recorded even if the recording magnetic field applied from the magnetic head is smaller than the coercive force of the magnetic recording medium.

  Japanese Patent Laid-Open No. 4-176034 also discloses an optically assisted magnetic recording method. In this document, in particular, with respect to a magnetic recording medium including a recording layer made of a ferrimagnetic material having a compensation temperature of about room temperature, the reproducing portion of the recording layer is irradiated with a light beam to increase the temperature during reproduction. A method for reproducing information by increasing magnetization and detecting magnetic flux leaking from a reproduction site is disclosed.

  Japanese Laid-Open Patent Publication No. 6-243527 also discloses an optically assisted magnetic recording method, which discloses a magnetic recording apparatus having a magnetic head and a semiconductor laser fixed on a slider. This document discloses a relationship between a high-temperature writing portion heated by laser light irradiation and a magnetic head facing position. In the magnetic recording apparatus of this document, a high-temperature region heated by laser light irradiation is disclosed. A magnetic head facing position exists inside.

  In the optically assisted magnetic recording type information recording apparatus disclosed in the above-mentioned document, a magnetic recording apparatus in which a magnetic head and an optical head are provided on one slider has been proposed. However, in practice, it is extremely difficult to manufacture the magnetic head and the optical head on one slider. In order to solve this problem, a method has been proposed in which a recording layer of a magnetic disk is irradiated with a laser beam narrowed down using a lens from a surface (substrate side) opposite to the magnetic head running surface of the magnetic disk. (For example, refer to Patent Documents 1 and 2). Even in such a method, it is possible to record information by sufficiently reducing the coercivity of the recording film, and high density is achieved.

JP 2001-243612 (page 6, FIG. 7) Japanese Patent Laid-Open No. 2001-216630 (page 11, FIGS. 5-6)

  In the optically assisted magnetic recording type recording / reproducing apparatus as shown in Patent Documents 1 and 2, the center of the head surface of the magnetic head at the time of information recording is required to perform high-density recording of information with high accuracy and stable operation. It is necessary to accurately focus the laser beam in the vicinity. The present invention has been made to solve this problem, and an object of the present invention is to provide optically assisted magnetism capable of focusing laser light more accurately near the center of the head surface of a magnetic head during information recording. It is an object to provide a recording type information recording apparatus and a head positioning method.

  According to a first aspect of the present invention, in an information recording apparatus for recording information by applying light and an external magnetic field to the information recording medium, a magnetic head for applying an external magnetic field to the information recording medium, and the information recording medium And an optical head that irradiates the information recording medium with light, and is disposed at a position facing the magnetic head, and irradiates the magnetic head with light emitted from the optical head through the information recording medium. And an information recording apparatus characterized in that a relative position between the optical head and the magnetic head in a direction perpendicular to the irradiation direction of the light is adjusted based on the reflected light from the magnetic head. The

  In the information recording apparatus of the present invention, it is preferable to further include a four-divided detector for detecting reflected light from the magnetic head.

  According to a second aspect of the present invention, in an information recording apparatus for recording information by applying light and an external magnetic field to the information recording medium, a magnetic head for applying an external magnetic field to the information recording medium, and the information recording medium An information recording apparatus is provided that includes an optical head that is disposed at a position opposite to the magnetic head and that irradiates light to the information recording medium, and a detector that detects reflected light from the magnetic head.

  The information recording apparatus of the present invention is an information recording apparatus of an optically assisted magnetic recording system, and is an information recording apparatus in which an optical head and a magnetic head are arranged at positions facing each other across an information recording medium. An example of the information recording apparatus of the present invention is shown in FIG. In the information recording apparatus 100 of FIG. 1, the magnetic head and / or the optical head is positioned by the following operation in order to focus the laser beam accurately near the center of the head surface of the magnetic head 2 during information recording. .

  First, radiated light from the optical head 3 is transmitted through the information recording medium 40 and irradiated onto the surface of the magnetic head 2. At this time, since the magnetic pole (core) on the surface of the magnetic head 2 has a high reflectance, the light irradiated on the surface of the magnetic head 2 is reflected on the surface of the magnetic head 2. Next, the reflected light from the magnetic head 2 is detected by the detector 8. Next, based on the reflected light detected by the detector 8, the optical head 3 and / or the magnetic head 2 is irradiated with light so that the emitted light from the optical head 3 is irradiated near the center of the head surface of the magnetic head 2. The relative position of the optical head 3 and the magnetic head 2 in the direction orthogonal to the light irradiation direction is adjusted. Since the information recording apparatus of the present invention can detect the reflected light from the magnetic head and adjust the relative position between the optical head and the magnetic head, the relative position of the optical head and the magnetic head can be adjusted accurately and easily in real time. Positioning becomes possible, and high-density recording of information with higher accuracy becomes possible.

  As the detector 8 for detecting the reflected light from the magnetic head 2 in FIG. 1, for example, a quadrant detector 8 as shown in FIG. 3 is preferable. The detector 8 that detects the reflected light from the magnetic head 2 may be provided in the optical head 3 as in the example of FIG. 1 or may be provided outside the optical head 3. The quadrant detector 8 shown in FIG. 3 includes four light receiving elements 8a to 8d for detecting reflected light intensity, and two rows of light receiving elements are arranged in the circumferential direction and the radial direction of the track of the information recording medium. ing.

  If the signal intensity of the reflected light detected by the light receiving elements 8a, 8b, 8c and 8d of the quadrant detector 8 in FIG. 3 is A, B, C and D, respectively, The circumferential differential signal = (A + B) − (C + D) and the radial differential signal = (A + C) − (B + D) are calculated from the reflected light intensities A to D detected by the light receiving elements 8a to 8d, respectively. To do. The circumferential differential signal is a signal for controlling the circumferential position of the track of the optical head and / or magnetic head, and the radial differential signal is the radial position of the track of the optical head and / or magnetic head. It is a signal for controlling.

  3 shows the vicinity of the center of the head surface of the magnetic head 2 for in-plane magnetic recording as shown in FIG. 2 (in FIG. 2, it is defined between the upper soft magnetic core 21 and the lower soft magnetic core 22). FIG. 6 is a diagram showing a state in which light is irradiated to the vicinity of the gap gap portion 24) and the reflected light 400 from the magnetic head 2 is detected by the quadrant detector 8. In the magnetic head 2 as shown in FIG. 2, the upper soft magnetic core 21 and the lower soft magnetic core 22 have high reflectivity, and the other portions are formed of ceramic or the like, so the reflectivity is low. Therefore, in the reflected light 400 detected by the quadrant detector 8, a region corresponding to the reflected light from the upper soft magnetic core 21 and the lower soft magnetic core 22 of the magnetic head 2, that is, a broken line 401 in FIG. In the other region 403, the reflected light intensity is low.

  When the irradiation light is applied to the center of the magnetic head (the center of the gap gap 24 in FIG. 2), as shown in FIG. 3, the signal intensity of the reflected light detected by each of the light receiving elements 8a to 8d. Have the same intensity, the circumferential differential signal and the radial differential signal are both substantially zero. However, when the irradiated light deviates from the center of the magnetic head, the signal intensity of the reflected light detected by each of the light receiving elements 8a to 8d is different, so at least one of the circumferential differential signal and the radial differential signal is It becomes almost zero. Therefore, in the information recording apparatus of the present invention, the optical head and / or the magnetic head are two-dimensionally arranged so that the circumferential differential signal and the radial differential signal obtained by the reflected light from the magnetic head are both substantially zero. The relative position between the optical head and the magnetic head is adjusted by moving in the circumferential direction and / or radial direction of the track by an actuator or the like. In the case of positioning by moving the optical head 3 with the information recording apparatus of FIG. 1, the positioning may be performed by moving the objective lens 4 in the optical head 3. Further, when positioning is performed by moving the magnetic head 2 in the information recording apparatus of FIG. 1, the magnetic head 2 may be positioned by moving the slider 1.

  According to the third aspect of the present invention, there is provided an information recording medium on which information is recorded and reproduced by the information recording apparatus according to the first and second aspects.

  The information recording medium of the present invention includes a substrate, a heat control layer formed on the substrate, a recording layer formed on the heat control layer, and a protective layer formed on the recording layer. Is preferred. The information recording layer is a layer on which information is magnetically recorded, and the thermal control layer is a layer for controlling heat applied to the recording layer when information is recorded on the recording layer by the optically assisted magnetic recording method. .

  In the information recording medium of the present invention, the transmittance of the information recording medium is preferably 25% or more, and in particular, the transmittance of the information recording medium is preferably 50% or more.

  According to the fourth aspect of the present invention, a magnetic head that applies an external magnetic field to the information recording medium, and a position that faces the magnetic head across the information recording medium, and irradiates the information recording medium with light. A head positioning method for an information recording apparatus for recording information by applying light and an external magnetic field to the information recording medium, wherein light emitted from the optical head is transmitted through the information recording medium. Irradiating the magnetic head, detecting reflected light from the magnetic head, and based on the detected reflected light, the optical head and the magnetic head in a direction perpendicular to the light irradiation direction. There is provided a head positioning method including adjusting a relative position with respect to the head.

  According to the information recording apparatus and the head positioning method of the present invention, the light emitted from the optical head is transmitted through the information recording medium to irradiate the surface of the magnetic head, and based on the reflected light from the magnetic head, the optical head, the magnetic head, Since the relative position of the optical head and the magnetic head can be adjusted in real time, the relative positioning of the optical head and the magnetic head can be performed more accurately and easily. Therefore, the information recording apparatus and the head positioning method of the present invention enable high-precision recording with high accuracy and stability.

  Hereinafter, embodiments of the information recording apparatus and the head positioning method according to the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these.

[Information recording device]
A schematic configuration diagram of the information recording apparatus of the embodiment is shown in FIG. An information recording apparatus 100 of this example is an information recording apparatus of an optically assisted magnetic recording system, and as shown in FIG. 1, a flying slider 1 incorporating a magnetic head 2 and a magnetic for controlling the position of the slider 1 are used. The head actuator 17, the optical head 3, the magnetic head actuator 17, and a controller 19 for controlling the optical head actuator 5 described later are configured. In the information recording apparatus 100 of this example, as shown in FIG. 1, the optical head 3 and the magnetic head 2 are irradiated so that the laser beam emitted from the optical head 3 is irradiated on the surface of the magnetic head 2 in the flying slider 1. Are arranged at positions facing each other across the magnetic disk 40, and the optical head 3 is arranged on the substrate 41 side of the magnetic disk 40. The magnetic head actuator 17 and the slider 1 are connected via an arm 18 as shown in FIG.

  A schematic configuration diagram of the magnetic head 2 used in this example is shown in FIG. The magnetic head 2 used in this example is a magnetic head for in-plane magnetic recording. As shown in FIG. 2 (a), the upper layer soft magnetic core 21, the lower layer soft magnetic core 22, and the lower layer soft magnetic core are mainly used. The coil 23 is wound around the magnetic core 22. The upper soft magnetic core 21 and the lower soft magnetic core 22 are made of FeNi alloy, Co alloy or the like. In the magnetic head 2 of this example, as shown in FIG. 2 (a), the upper end soft magnetic core 21 and the lower soft magnetic core 22 (the lower end in FIG. 2), that is, on the head surface of the magnetic head 2. A gap gap 24 defined between the upper soft magnetic core 21 and the lower soft magnetic core 22 is formed. In such a magnetic head 2 for in-plane magnetic recording, a magnetic field is generated in the gap gap portion 24 defined between the upper soft magnetic core 21 and the lower soft magnetic core 22 by passing a current through the coil 23. To do.

  On the other hand, as shown in FIG. 1, the optical head 3 is provided with an objective lens 4, an optical head actuator 5 for controlling the position of the objective lens 4, and a laser beam for heating the magnetic disk 20 during information recording. A semiconductor laser 6 to be emitted, a focus system detector 7 for detecting the focus position of the laser beam, a positioning detector 8 for detecting an irradiation position in a direction orthogonal to the laser beam irradiation direction, and two beams Splitters 9 and 10, collimator lenses 11, two condenser lenses 12 and 13, and two prisms 14 optical elements are provided. In this example, the optical head actuator 5 can adjust the position of the objective lens 4 in three dimensions.

  In the optical head 3 of the information recording apparatus 100 of this example, as shown in FIG. 1, in the optical path between the semiconductor laser 6 and the objective lens 4, the beam splitter 9, the two prisms 14 and the collimator are arranged from the objective lens 4 side. The optical element of the lens 11 is arranged. Further, in the optical path between the beam splitter 9 and the positioning detector 8, a beam splitter 10 and a condenser lens 13 are arranged from the beam splitter 9 side as shown in FIG. Further, a condensing lens 12 is arranged in the optical path between the beam splitter 10 and the focus system detector 7 as shown in FIG.

  Next, the head positioning detector 8 and the head positioning principle used in the information recording apparatus 100 of this example will be described. FIG. 3 shows a schematic configuration diagram of the positioning detector 8 used in this example. In this example, as shown in FIG. 3, a four-divided light receiving element (four-divided detector) is used as the positioning detector 8. As shown in FIG. 3, the positioning detector 8 in this example includes four light receiving elements 8a to 8d, and the four light receiving elements 8a to 8d are arranged in two rows in the circumferential direction and the radial direction of the track. .

  If the signal intensity of the reflected light detected by the light receiving elements 8a, 8b, 8c and 8d constituting the positioning detector 8 is A, B, C and D, respectively, the light receiving elements 8a to 8a of the positioning detector 8 of this example. The signal intensities A to D of the reflected light detected at 8d are sent to the controller 19, where the circumferential differential signal = (A + B) − (C + D) and the radial differential signal = (A + C) − ( B + D) is calculated. The circumferential differential signal is a signal for controlling the circumferential position of the track of the optical head 3 and / or the magnetic head 2, and the radial differential signal is a track of the optical head 3 and / or the magnetic head 2. It is a signal for controlling the position of the radial direction.

  FIG. 3 is a view showing a state when reflected light from the magnetic head 2 (broken line 400 in FIG. 3) is detected by the positioning detector 8, and the head surface of the magnetic head 2 shown in FIG. FIG. 2 is a diagram showing a reflected light intensity distribution when light is irradiated in the vicinity of the center (in FIG. 2, in the vicinity of the gap gap portion 24 defined between the upper soft magnetic core 21 and the lower soft magnetic core 22) It is. In the magnetic head 2 as shown in FIG. 2, the upper soft magnetic core 21 and the lower soft magnetic core 22 have high reflectivity, and the other portions are formed of ceramic or the like, so the reflectivity is low. Therefore, in the reflected light 400 detected by the positioning detector 8, the region corresponding to the reflected light from the upper soft magnetic core 21 and the lower soft magnetic core 22 of the magnetic head 2, that is, the broken line 401 in FIG. The reflected light intensity in the area surrounded by 402 is high, and the reflected light intensity is low in the other areas 403.

  When the laser beam is applied to the center of the magnetic head 2 (the center of the gap gap 24 in FIG. 2), the reflected light signals detected by the light receiving elements 8a to 8d as shown in FIG. Since the intensities are equal, both the circumferential differential signal and the radial differential signal calculated by the controller 19 are almost zero. However, when the laser beam deviates from the center of the magnetic head 2, the signal intensity of the reflected light detected by each of the light receiving elements 8a to 8d is different, so that the circumferential differential signal and the radial direction calculated by the controller 19 are different. At least one of the differential signals is almost zero.

  Therefore, in the information recording apparatus 100 of this example, the controller 19 controls the optical head actuator 5 so that the circumferential differential signal and the radial differential signal obtained from the reflected light from the magnetic head 2 are both substantially zero. And / or the magnetic head actuator 17 is controlled to move the optical head 3 and / or the magnetic head 2 in the circumferential direction and / or the radial direction of the track, thereby adjusting the relative position between the optical head 3 and the magnetic head 2. By positioning the head by such a method, information can be easily recorded with high accuracy in the optically assisted magnetic recording system.

  In the information recording apparatus 100 of this example, when adjusting the relative position between the optical head 3 and the magnetic head 2, as shown in FIG. 1, the circumferential differential signal and radial direction obtained from the reflected light from the magnetic head 2. Based on the differential signal, both the optical head 3 and the magnetic head 2 are moved in the track circumferential direction and / or the radial direction by a control signal (broken arrows 19b and 19c in FIG. 1) output from the controller 19. However, one of the optical head 3 and the magnetic head 2 may be moved in the track circumferential direction and / or radial direction. However, when the optical head 3 is moved, it is preferable to position the optical head 3 by moving the objective lens 4. When the magnetic head 2 is moved, it is preferable to position the magnetic head 2 by moving the slider 1 in which the recording head 2 is incorporated. In this example, the controller 19 uses the controller 19 to drive the optical head 3 and / or the magnetic head 2 depending on the situation (for example, the relative position between the optical head 3 and the magnetic head 2 immediately before adjustment). The head actuator 5 and the magnetic head actuator 17 were controlled.

[Magnetic disk]
A schematic cross-sectional view of the magnetic disk 40 recorded and reproduced by the information recording apparatus 100 of this example is shown in FIG. As shown in FIG. 4, the magnetic disk 40 used in this example has a configuration in which a thermal control layer 42, a recording layer 43, and a protective layer 44 are sequentially laminated on a substrate 41. The recording layer 43 is a layer on which information is magnetically recorded, and the thermal control layer 42 is a layer for controlling heat applied to the recording layer 43 when information is recorded on the recording layer 43 by the optically assisted recording method. is there. The protective layer 44 is a layer for protecting the recording layer 43.

The magnetic disk 40 used in this example was manufactured as follows. First, a glass substrate 1 having a diameter of 2.5 inches (about 6.35 cm) and a thickness of 0.6 mm was prepared. Next, an AlTi ₂ film was formed on the substrate 41 as the thermal control layer 42 by RF magnetron sputtering. The film thickness of the thermal control layer 42 was 5 nm. Next, a Tb ₁₈ Fe ₆₈ Co ₁₄ alloy film was formed as the recording layer 43 on the thermal control layer 42 by RF magnetron sputtering. The film thickness of the recording layer 43 was 40 nm. Finally, a C (carbon) film was formed as a protective layer 44 on the recording layer 43 by DC magnetron sputtering. The thickness of the protective layer 44 was 5 nm. Thus, the magnetic disk 40 used in this example was produced.

  In this example, various magnetic disks 40 having a transmittance of 10 to 80% in the magnetic disk 40 were produced. The transmittance of the magnetic disk was adjusted by changing the film thickness of the thermal control total 42 and the film thickness of the recording layer 43.

[Information recording and head positioning method]
An information recording method in the information recording apparatus of this example will be described with reference to FIG. First, laser light is emitted from the semiconductor laser 6 in the optical head 3. The laser light emitted from the semiconductor laser 6 is converted into parallel light by the collimator lens 11 and then shaped by the two prisms 14. Next, the laser light is incident on the objective lens 4 through the beam splitter 9. The laser light incident on the objective lens 4 is focused on the recording layer near the gap of the core of the magnetic head 2 by the objective lens 4. Next, information is recorded by applying a magnetic field from the magnetic head 2 to the region of the recording layer that has been heated by the irradiation of the laser light and has a reduced coercive force.

  The focus control of the laser beam in the information recording apparatus of this example was performed according to the following procedure. Reflected light from the magnetic disk 40 is detected by the focus system detector 7, and the optical head actuator 5 is feedback controlled based on the detected reflected light (broken line arrow 19b in FIG. 1), and the objective lens 4 is controlled by the laser light. The focus position was adjusted by moving in the irradiation direction. In the focus control when the laser beam is focused by the information recording apparatus of this example, the focus position of the laser beam is detected by a signal obtained by the astigmatism method, the knife edge method, etc., as in a normal optical disk drive. Based on this signal, the optical head actuator 5 is feedback-controlled by the controller 19.

  Next, the optical head in the information recording apparatus of this example and the positioning method of the relative position in the direction orthogonal to the laser beam irradiation direction of the recording head will be specifically described with reference to FIGS. First, the magnetic disk 40 is irradiated with laser light emitted from the semiconductor laser 6 in the optical head 3 (step S1 in FIG. 6). At this time, if the transmittance of the magnetic disk 40 is not 0, the laser light is transmitted through the magnetic disk 40 and irradiated to the vicinity of the gap gap 24 of the core on the surface of the magnetic head 2. This state is shown in FIG. 2B, in which the laser light is applied to the magnetic head so that the upper soft magnetic core 21 and the lower soft magnetic core 22 of the recording head 2 are within the spot diameter of the laser light 300. 2 Irradiate the surface. At this time, since the reflectivity of the upper soft magnetic core 21 and the lower soft magnetic core 22 of the magnetic head 2 is high, the reflected light from the magnetic head 2 returns to the optical head 3.

  Next, the reflected light returning to the optical head 3 passes through the objective lens 4 and enters the beam splitter 9 and is separated by the beam splitter 9 as shown in FIG. The reflected light 16 separated by the beam splitter 9 is guided to the positioning detector 8 through the beam splitter 10 and the condenser lens 13 as shown in FIG.

  Next, the signal intensity of the reflected light guided to the positioning detector 8 is detected by the four-divided light receiving elements 8a to 8d as shown in FIG. 3 (step S2 in FIG. 6), and the detection signal is input to the controller 19. (Dotted line arrow 19a in FIG. 1). Next, the controller 19 calculates the circumferential differential signal (A + B) − (C + D) and the radial differential signal (A + C) − from the signal intensities A to D of the reflected lights detected by the light receiving elements 8a to 8d. (B + D) is calculated (step S3 in FIG. 6).

  Next, it is determined whether or not both the circumferential differential signal and the radial differential signal calculated by the controller 19 are 0 (step S4 in FIG. 6). When both the circumferential direction differential signal and the radial direction differential signal are 0, the laser beam irradiated from the optical head 3 is irradiated to the center of the gap gap portion 24 of the core of the magnetic head 2. Therefore, information recording is performed in this state without changing the relative positions of the optical head 3 and the magnetic head 2.

  If at least one of the circumferential differential signal and the radial differential signal is not 0 in step S4 in FIG. 6, the irradiation position of the laser beam from the optical head 3 is deviated from the center of the magnetic head 2. The optical head actuator 5 and / or the magnetic head actuator 17 are driven on the basis of the control signals 19b and / or 19c of the controller 19 so that both the circumferential differential signal and the radial differential signal become zero. The head 3 (objective lens 4 in this example) and / or the magnetic head 2 (slider 1 in this example) are moved in the circumferential direction and / or radial direction of the track (step S5 in FIG. 6). Thereafter, as shown in FIG. 6, the process returns to step S3 in FIG. Information recording is performed when both the circumferential differential signal and the radial differential signal become 0 in step S4 in FIG. Here, while feedback control is performed on the relative position between the optical head 3 and the magnetic head 2 based on the circumferential differential signal and the radial differential signal, the laser head is continuously irradiated and the magnetic head 2 is irradiated. It is assumed that the reflected light from the camera continues to be detected. In FIG. 6, the circumferential differential signal and the radial differential signal are controlled to be 0, but the present invention is not limited to this, and both the circumferential differential signal and the radial differential signal are both. Control may be performed so that the value is within a predetermined range slightly deviated from 0, and the allowable range can be appropriately set according to the situation.

[Head positioning test]
Next, the magnetic disks 40 having different transmittances manufactured in this example were mounted on the information recording apparatus 100 of FIG. 1, and a head positioning test was performed according to the flowchart shown in FIG. As a result, it was found that the head can be positioned satisfactorily with the magnetic disk 40 having a transmittance of 25% or more.

[Application example]
In this example, a magnetic disk 50 in which a thermal control layer 42, a recording layer 43, and a protective layer 44 were sequentially provided on both surfaces of a substrate 41 as shown in FIG. A magnetic disk 50 was manufactured in the same manner as in the example except that the thermal control layer 42, the recording layer 43, and the protective layer 44 were provided on both sides of the substrate 41. In this example, various magnetic disks 50 having different transmittances were produced in the same manner as in the example.

  Similarly to the example, various magnetic disks 50 having different transmittances manufactured in this example were mounted on the information recording apparatus 100 of FIG. 1 and a head positioning test was performed. As a result, it was found that the head can be positioned satisfactorily with the magnetic disk 50 having a transmittance of 50% or more.

  In the information recording apparatus of the above embodiment, the recording head for in-plane magnetic recording has been described, but the present invention is not limited to this. Even in the case of a ring head used in the perpendicular magnetic recording system or a single magnetic pole recording head, a circumferential differential signal and a radial differential signal can be obtained from the four-divided light receiving element as shown in FIG. Therefore, in principle, it can be similarly applied and the same effect can be obtained.

  According to the information recording apparatus and the head positioning method of the present invention, the radiation light from the optical head is transmitted through the information recording medium and irradiated onto the surface of the magnetic head, the reflected light from the magnetic head is detected, and the irradiation direction of the laser light Since the relative position between the optical head and the magnetic head in the direction orthogonal to each other is adjusted, the relative alignment between the optical head and the magnetic head can be performed accurately and easily in real time. Therefore, the information recording apparatus and the head positioning method of the present invention enable high-density recording with higher accuracy and stability, and are suitable as an information recording apparatus of the optically assisted magnetic recording system.

FIG. 1 is a schematic configuration diagram of an information recording apparatus according to an embodiment. FIG. 2 is a schematic configuration diagram of a recording head used in the information recording apparatus of the example, FIG. 2A is a schematic cross-sectional view, and FIG. 2B is a diagram of the recording head viewed from the laser light incident side. It is a schematic plan view. FIG. 3 is a schematic configuration diagram of a positioning detector used in the information recording apparatus of the embodiment. FIG. 4 is a schematic cross-sectional view of the magnetic disk manufactured in the example. FIG. 5 is a schematic cross-sectional view of a magnetic disk manufactured in an application example. FIG. 6 is a flowchart of the head positioning method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Slider 2 Magnetic head 3 Optical head 4 Objective lens 5 Optical head actuator 6 Semiconductor laser 7 Focus system detector 8 Positioning detector 17 Magnetic head actuator 19 Controllers 40 and 50 Magnetic disk 100 Information recording device

Claims (8)

In an information recording apparatus for recording information by applying light and an external magnetic field to an information recording medium,
A magnetic head for applying an external magnetic field to the information recording medium;
An optical head disposed at a position facing the magnetic head across the information recording medium and irradiating the information recording medium with light;
The light emitted from the optical head is transmitted through the information recording medium to irradiate the magnetic head, and based on the reflected light from the magnetic head, the optical head in a direction perpendicular to the light irradiation direction An information recording apparatus characterized in that a relative position with respect to the magnetic head is adjusted. The information recording apparatus according to claim 1, further comprising a four-divided detector that detects reflected light from the magnetic head. In an information recording apparatus for recording information by applying light and an external magnetic field to an information recording medium,
A magnetic head for applying an external magnetic field to the information recording medium;
An optical head disposed at a position facing the magnetic head across the information recording medium and irradiating the information recording medium with light;
An information recording apparatus comprising: a detector that detects reflected light from the magnetic head. An information recording medium on which information is recorded and reproduced by the information recording apparatus according to claim 1. The information recording medium includes a substrate, a heat control layer formed on the substrate, a recording layer formed on the heat control layer, and a protective layer formed on the recording layer. The information recording medium according to claim 4. 6. The information recording medium according to claim 4, wherein the transmittance of the information recording medium is 25% or more. 6. The information recording medium according to claim 4, wherein the transmittance of the information recording medium is 50% or more. An information recording medium comprising: a magnetic head that applies an external magnetic field to the information recording medium; and an optical head that is disposed at a position facing the magnetic head across the information recording medium and that irradiates the information recording medium with light. A head positioning method of an information recording apparatus for recording information by applying light and an external magnetic field to
Irradiating the magnetic head with light emitted from the optical head through the information recording medium;
Detecting reflected light from the magnetic head;
A head positioning method including adjusting a relative position between the optical head and the magnetic head in a direction perpendicular to the irradiation direction of the light based on the detected reflected light.

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