JP2001093236A - Information recording medium, its recording/reproducing device and head positioning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information recording medium suppressing a floating amount of a recording/reproducing head and performing high density recording/ reproducing and its recording/reproducing device. SOLUTION: The information recording medium 143 is provided with a recording layer 101 on a flat substrate 100. A servo pattern and control information are recorded beforehand on the recording layer 101 as a magnetic mark with a servo writer, etc. Since an irregular pattern is eliminated on the substrate 100, a slider 103 is floated to a fixed level, and with the floating amount smaller than usual through the whole area of a medium surface. At an information recording time, a position of the slider 103 is controlled based on a magneto- optical signal from the magnetic mark of the information recording medium. At an information reproducing time, the position of the slider 103 is controlled based on a leakage magnetic field from the magnetic mark by the reproducing magnetic head 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium in which information is recorded as a magnetic mark by applying light and an external magnetic field, and information is reproduced by detecting a leakage magnetic field from the magnetic mark, and a recording / reproducing apparatus therefor. More specifically, the present invention relates to a head positioning method, and more particularly, to an information recording medium capable of preventing a head crash due to contact of a recording head or a reproducing head with the information recording medium, and to reliably position those heads on desired information tracks. The present invention relates to a novel recording / reproducing apparatus and a head positioning method capable of performing the same.

[0002]

2. Description of the Related Art A magneto-optical recording medium such as a magneto-optical disk is known as an external memory of a computer or the like. Magneto-optical recording media are widely used as recording media in the multimedia era because information can be rewritten and large-capacity data such as moving images and audio can be handled. In order to record / reproduce information on the magneto-optical recording medium, laser light is condensed on the optical recording medium using a focusing lens to form an optical spot, and the optical spot is locally heated by the optical spot. At the same time, an information mark is recorded on the information track by applying a magnetic field corresponding to the recording information to the heated area. At the time of information reproduction, a laser beam having a lower laser power than at the time of recording is irradiated to the information mark area,
The information is reproduced by detecting the magneto-optical effect generated according to the presence or absence of the information mark.

In order to improve the recording density of a magneto-optical recording medium, it is conceivable to reduce the interval between information tracks (track pitch) and the arrangement interval of information marks in the light spot scanning direction (mark pitch). Can be However, when the track pitch and the mark pitch are smaller than the diameter of the light spot, when the light spot irradiates one information mark, a part of another information mark existing around the information mark is also irradiated at the same time. This causes a problem that the signal of the surrounding information mark leaks into the signal of the information mark to be reproduced. This leakage interferes as a noise component with a reproduction signal from an information mark to be reproduced, and lowers the spatial resolution during reproduction, so that information cannot be reproduced with high accuracy. Therefore, the size of the track pitch and the mark pitch is limited by the diameter of the light spot.

[0004] The diameter Ws of the light spot is represented by a value of approximately λ / NA by the wavelength λ and the numerical aperture (NA) of the aperture lens. For example, when a solid immersion lens is used with a blue light source (λ = 413 nm) (effective NA =
1.2), the spot diameter Ws is about 0.34 μm. Here, while reducing the track pitch, 0.09 μ corresponding to a quarter of Ws in the direction along the information track.
It is assumed that minute marks are recorded at a mark pitch of m or less.
When such a minute mark is reproduced with a light spot having a diameter of 0.34 μm, a signal from another minute mark located before and after the minute mark in the track direction leaks, and the reproduced signal from the minute mark cannot be distinguished. Would.

On the other hand, in the current magnetic disk device, even if a minute information mark having a mark pitch of about 0.07 μm is formed on the magnetic disk, a reproduction signal having a sufficient signal amplitude can be obtained from the minute information mark. I have. This is because the magnetic head used for reproduction has a high spatial resolution. As described above, in an optical disc device equipped with a laser having a specific wavelength and a focusing lens, the spot diameter that determines the spatial resolution during reproduction is considerably larger than that of a minute information mark, and thus the reproduction resolution is low. Was an obstacle.

As a method for solving this problem, "Proceedi
ngs of Magneto-Optical RecordingInternational Symp
Osium '99 pp. 225-228 ”has been proposed. In this magneto-optical fusion system, a magneto-optical recording medium is used as an optical recording medium. When recording information on a magneto-optical recording medium, an optical head for irradiating a laser beam and a magnetic head for applying a magnetic field are scanned on the medium in the same manner as in a conventional optical disk device, so that the information is recorded on an information track of the magneto-optical recording medium. Information is recorded by forming an information mark indicating whether the magnetization direction is upward or downward with respect to the surface of the magneto-optical recording medium.

On the other hand, when reproducing information, the same reproducing means as that of a conventional magnetic disk drive is used. That is, using a magnetic head equipped with a magnetoresistive element, a leakage magnetic field from an information mark recorded on a magneto-optical recording medium is detected,
Play the recorded information. The thickness of this magnetoresistive element in the direction along the information track (track direction) is about several tens of nm, which is about one digit smaller than the light spot diameter. Therefore, the reproduction resolution in the track direction can be higher when reproduction is performed using the magnetoresistive element. Also, in the direction orthogonal to the information tracks (track width direction), the resolution of reproduction can be improved by reducing the width of the magnetoresistive element in the track width direction. Thus, in the optical-magnetic fusion method,
By detecting information using a magnetic head equipped with a magnetoresistive element at the time of reproduction, information leakage, which has been a problem in conventional optical disk devices, is resolved, and high density is achieved by narrowing track pitch and mark pitch. Was realized.

In such a light-magnetic fusion system, Japanese Patent Laid-Open No. 2-2 has disclosed a means for causing a magnetic head to follow an information track.
The method described in 18016 is used. In this method, uneven pits having a magnetically readable structure are provided in a predetermined area of a magneto-optical recording medium, and a leakage magnetic field generated from the pit ends of the uneven pits is detected as a tracking signal using a magnetic head. This is a method for controlling the position of the magnetic head based on the tracking signal. When the optical head is to follow the information track, the position of the optical head is controlled by using the sample pit tracking method used in the conventional optical disk device by using the concave and convex pits.

[0009]

As described above, in the magneto-optical recording medium used in the magneto-optical fusion system, concave and convex pits for causing the magnetic head and the optical head to follow the information track are formed in a predetermined area. . However, when a slider on which a magnetic head or an optical head is mounted scans over an area where uneven pits are present, the flying height decreases, and there is a problem that the slider comes into contact with the magneto-optical recording medium and a head crash occurs. Was. Conventionally, the flying height of the slider has been set to a large value in advance so that a head crash does not occur even if the flying height of the slider decreases in a region where the uneven pits are formed.

[0010] The leakage magnetic field from an information mark that has been miniaturized for higher density is smaller than the leakage magnetic field from an information mark recorded at a lower density. Therefore, in order to reproduce high-density recorded information, there is a demand to reduce the flying height of the slider as much as possible in order to reliably detect a small leakage magnetic field from a minute information mark. However, in the optical-magnetic fusion method, as described above, if the flying height of the slider is set to a small value, a head crash is likely to occur in the area where the concave and convex pits are formed. It was difficult to play. In addition, when a concavo-convex pattern is formed on the surface of the magneto-optical recording medium, dust and the like accumulate in the concave portions of the concavo-convex pattern, which is another factor of head crash.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a head crash even when the flying height of the head is reduced to reproduce a minute mark having a weak leakage magnetic field. It is an object of the present invention to provide an information recording medium suitable for an optical-magnetic fusion system capable of reliably reproducing information without performing.

It is another object of the present invention to provide a novel recording / reproducing apparatus and a head positioning method capable of reliably positioning an optical head, a recording magnetic head, and a reproducing magnetic head on desired tracks. It is in.

[0013]

According to a first aspect of the present invention, a magnetic layer is provided on a flat substrate, and information is recorded by applying light and an external magnetic field to a data area of the magnetic layer. In the information recording medium, there is provided an information recording medium, wherein management information and a servo pattern for managing a data area are formed as magnetic marks on the magnetic layer.

In the information recording medium of the present invention, management information for managing the data area and a track servo pattern required for tracking the data area are formed on the magnetic layer as magnetic marks. For example, as shown in FIG. 5, a data storage area 502 for recording information and a positioning area 501 for positioning an optical head or a magnetic head can be formed on the information recording medium. The positioning area 501 includes, for example, a synchronization area 503 and an erasing area 50.
4, track code area 505, track servo area 5
06. Magnetic marks are formed in each of these areas, and these magnetic marks are called management information marks because they are read to manage the data area. These management information mark groups can be recorded in a desired pattern using a servo writer used in a magnetic disk device.

Further, since the information recording medium of the present invention does not have a concavo-convex pattern formed on the disk as in the conventional optical-magnetic fusion system, the slider on which the recording head and the reproducing head are mounted can be moved over the entire surface of the disk. It is possible to levitate in a stable state. Therefore, it is not necessary to set a large flying margin of the slider from the viewpoint of head crash prevention. That is, the flying height of the recording head and the reproducing head from the information recording medium can be reduced, and a small information mark having a weak leakage magnetic field can be formed to increase the recording density.

According to a second aspect of the present invention, in a recording / reproducing apparatus for recording / reproducing an information recording medium, a magnetic layer is provided on a flat substrate as the information recording medium, and a servo pattern is provided on the magnetic layer. And an optical head for irradiating the information recording medium with light during information recording using an information recording medium on which management information is recorded as magnetic marks, and a recording magnetic head for applying a recording magnetic field to the information recording medium When,
At the time of information reproduction, a reproducing magnetic head for detecting a leakage magnetic field from a magnetic mark recorded on the magnetic layer, and the optical head and the recording magnetic head on a desired track based on a magneto-optical signal from the magnetic mark. The first to position
A recording apparatus comprising: a positioning device; and a second positioning device for detecting a leakage magnetic field from the magnetic mark with a reproducing magnetic head and positioning the reproducing magnetic head on a desired track when reproducing information. A playback device is provided.

In the recording / reproducing apparatus of the present invention, an information recording medium in which servo patterns, management information and the like are formed in advance as magnetic marks is used as the information recording medium to be used. While irradiating light to a desired track position using an optical head on such an information recording medium, an external magnetic field is applied using a recording magnetic head to the irradiated area to record information as a magnetic mark. In reproducing information, the information is reproduced by detecting a leakage magnetic field from the magnetic mark by, for example, a reproducing magnetic head having a magnetoresistive element.

In order to position an optical head and a recording magnetic head on a desired track during recording of information, a laser beam is irradiated on a magnetic mark as a servo pattern or management information using an optical head, and light from the magnetic mark is irradiated. Detect the magnetic signal. Then, the first positioning device generates a servo error signal and management information based on the detected signal, and performs position control of the optical head and the recording magnetic head based on the servo error signal and management information. The first positioning device includes, for example, a photodetector that detects a polarization component included in light reflected from the magnetic mark and outputs a detection signal (magnetomagnetic signal), and a detection signal from the magnetic mark detected by the photodetector. , A first control signal generator for acquiring track position information of an optical head and a recording magnetic head and generating a control signal for arranging the heads at desired track positions, and an optical head based on the control signals. And a first actuator for driving the recording magnetic head to a desired track position.

On the other hand, at the time of reproducing information, in order to position the reproducing magnetic head at a desired track position, a leakage magnetic field from a magnetic mark as a servo pattern or management information is detected using the magnetic head. Then, the second positioning device generates a servo error signal and a management information signal based on the signal detected by the magnetic head, and performs position control of the magnetic head based on the servo error signal and the management information signal.
The second positioning device obtains, for example, current track position information of the reproducing magnetic head from a signal from the magnetic mark detected by the reproducing magnetic head, and controls the reproducing magnetic head at a desired track position. It can be configured using a second control signal generator that generates a signal, and a second actuator that drives the reproducing magnetic head to a desired track position based on a control signal from the second control signal generator. When the optical head, the recording magnetic head, and the reproducing magnetic head are provided on the same slider, the second actuator can be replaced with the first actuator.

Incidentally, in the conventional optical disk device, the optical recording medium to be used is formed with servo patterns, management information, and the like having irregularities during manufacture. At the time of recording or reproducing information, an optical head is used to irradiate the embedded information of these irregularities with laser light to detect diffracted light generated by the irregularities. And from the detected result,
The tracking or seek operation of the optical head is performed by detecting at which position on the optical recording medium the optical head is located and how much the optical head is displaced from the information track. Also, in a recording / reproducing apparatus according to the optical-magnetic fusion system, tracking and seek operations of an optical head and a magnetic head are performed based on diffracted light by a concavo-convex pattern, following the configuration of the optical disk apparatus. The recording / reproducing apparatus of the present invention reproduces a servo pattern or management information recorded as a magnetic mark on an information recording medium using a magneto-optical effect, and performs tracking or seek of an optical head based on the reproduced magneto-optical signal. The operation differs greatly from the conventional optical disk device.

On the other hand, in a conventional magnetic disk drive, a medium in which embedded information composed of a concavo-convex pattern is not formed is generally used as a magnetic recording medium to be used.
That is, before recording or reproducing information, a medium is used in which a servo pattern or management information in which information is provided in the direction of magnetization using a servo writer is formed in advance.
At the time of recording or reproducing information, the leakage magnetic field from these servo patterns and management information is detected by, for example, a reproducing magnetic head having a magnetoresistive element, and from the detected signal, the magnetic head exists at any position on the magnetic recording medium. In addition, the magnetic head performs tracking and seek operations by detecting how much the magnetic head deviates from the information track. The recording and reproducing apparatus of the present invention, when reproducing information,
Controlling the position of the magnetic head for reproduction based on the servo pattern and the magnetic mark of the management information is the same as in a conventional magnetic disk drive, but when recording information, the recording The control of the position of the magnetic head differs greatly. Further, the magnetic disk drive is greatly different from the conventional magnetic disk drive in that an optical system for detecting a magneto-optical signal from a magnetic mark and an optical system for heating an information recording medium during information recording are provided.

With this configuration, it is possible to realize an optical-magnetic fusion system using a flat disk. This improved optical-magnetic fusion method allows the recording or reproducing head to fly closer to the disk surface without colliding with the surface. therefore,
Even with a magnetic mark that is miniaturized for high density, tracking and seek operations and information reproduction can be performed with good sensitivity.

In the recording / reproducing apparatus of the present invention, for example, an MR head or a GMR head can be used as a reproducing magnetic head for reproducing information by detecting a leakage magnetic field from a magnetic mark during information reproduction. Since these heads can reliably detect a leakage magnetic field from a minute magnetic mark, they are suitable as a magnetic head for reproducing an information recording medium on which high-density recording is performed.

According to a third aspect of the present invention, in a head positioning method for positioning an optical head, a recording magnetic head, and a reproducing magnetic head at predetermined track positions on an information recording medium, An information recording medium having a magnetic layer on a flat substrate, on which a servo pattern and management information are recorded as magnetic marks, and irradiating the management information mark group with laser light when recording information; A magneto-optical signal from the management information mark group is detected by the control unit, and the positions of the optical head and the recording magnetic head are controlled based on the detected magneto-optical signal. Using a reproducing magnetic head, and controlling the position of the reproducing magnetic head based on the detected signal. It is provided.

In the head positioning method of the present invention, as shown in FIG. 3, in order to make the light spot 512 follow the information track 511 at the time of information recording, the servo pattern recorded as a magnetic mark in the track servo area 506 is used. 507-510, track code area 505
Track code 51 recorded as a magnetic mark
7 are scanned by the light spot 512, and the magneto-optical signals of those magnetic marks are detected. The optical head, that is, the position where the light spot 512 is formed, is controlled based on the magneto-optical signal.

On the other hand, as shown in FIG.
In order for the reproducing magnetic head (MR head) 513 to follow the information track 511, the track servo area 50 is required.
6 servo pattern 5 recorded as a magnetic mark
The position of the magnetic head 513 is controlled by detecting the leakage magnetic field from the track code 517 recorded in the track code area 505 as a magnetic mark in the reproduction magnetic head 513.

As described above, the positions of the optical head, the recording magnetic head, and the reproducing magnetic head can be controlled based on the magnetic marks formed in advance on the information recording medium having the flat substrate. In the optical-magnetic fusion system using the information recording medium according to the above aspect, the optical head and the magnetic head can be reliably arranged at desired track positions without colliding the optical head or the magnetic head with the surface of the information recording medium.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the information recording medium and the recording / reproducing apparatus according to the present invention will be described below in detail with reference to the drawings, but the present invention is not limited to these. In the following description, the same or similar components are denoted by the same reference numerals.

[0029]

FIG. 1 is a schematic diagram showing an example of a recording / reproducing apparatus according to the present invention. First, the recording / reproducing head of the recording / reproducing apparatus will be described.

(Recording / Reproducing Head) Recording / Reproducing Head 102
Includes an optical system such as a stop lens 109 and a solid immersion lens (SIL) 110 used for recording, a coil 104 for applying a magnetic field during recording, and a magnetic head 105 for reproduction. These are mounted on the slider 103 attached to the tip of the swing arm 141. The magneto-optical recording medium 143 has a disk shape and can be rotated by a rotation motor (not shown). Magneto-optical recording medium 1
Details of 43 will be described later. Magneto-optical recording medium 143
Is rotated, the magneto-optical recording medium 143 and the slider 10
And air enters between the slider 10 and the slider 10.
3 flies above the magneto-optical recording medium 143. The floating force and the swing arm 141 cause the magneto-optical recording medium 14
By balancing the force pressed against 3,
The slider 103 can be floated from the magneto-optical recording medium 143 by a fixed amount. In this embodiment, the flying height is about 3
It was set to be 0 nm.

A semiconductor laser 106 was used as a laser light source, and the wavelength λ was 660 nm. The laser light emitted from the semiconductor laser 106 is polarized light and divergent light. The collimator lens 107 is used to convert the diverging laser light into parallel light. The collimated laser light enters the aperture lens 109 via the beam splitter 108, and the laser light converged by the aperture lens 109 is converted into a solid immersion lens (SI
L) and is condensed on the bottom surface thereof. The aperture lens 109 of this embodiment has a numerical aperture NA of 0.6. The SIL 110 is a hemispherical lens obtained by processing glass having a refractive index of 1.8 into a hemispherical shape, and has an effective NA of about 1.1. The diameter of the light spot formed by being condensed on the bottom surface of the SIL 110 is defined by λ / effective NA, and is about 0.6 μm. The laser light condensed on the bottom surface of the SIL 110 permeates the magneto-optical recording medium 143 as evanescent light when the flying height of the slider 103 from the magneto-optical recording medium 143 is about 1/10 or less of the light source wavelength λ. Soup Then, a light spot 512 having substantially the same diameter as the above is formed on the recording film 101.
Form on top. That is, since the light source wavelength λ is 660 nm and the flying height is 30 nm, which is 1/10 or less of the light source wavelength λ, the above condition is satisfied, and the spot 512 having a diameter of about 0.6 μm is formed on the recording film 101. You.

(Magneto-optical recording medium and recording of management information) As shown in FIG. 6, the magneto-optical recording medium 143 has a recording film 101, a protective film 162, and a lubricating layer 1 on a flat substrate 100.
63 have a laminated structure. The recording film 101
This is a layer in which information is recorded as the direction of magnetization, and a magnetic material having perpendicular magnetization, for example, TbFeCo can be used similarly to the recording layer of a conventionally used magneto-optical recording medium. The protective layer 162 is a layer for protecting the recording layer from abrasion and corrosion, and can be made of, for example, SiN. The lubricating layer is a layer for ensuring running durability of the head on the medium, and for example, perfluoropolyether can be used. In the present invention, as the recording film 101, any of an in-plane magnetization film and a perpendicular magnetization film can be used.

FIG. 5 is a schematic plan view of the magneto-optical recording medium 143 viewed from the recording surface side. On the magneto-optical recording medium 143, a positioning area 501 and a data storage area 502 are formed. In the positioning area 501, information for managing the data storage area and information for controlling the position of the light spot 512 and the magnetic head 513 are recorded before recording / reproducing. Specifically, before recording or reproducing information, the synchronization pattern 515 is recorded in the synchronization area 503 in the positioning area 501, and the track code start pattern 516 and the track code 51 are recorded in the track code area 505.
7 is recorded, and servo patterns 507 to 510 are written in the track servo area 506 in advance. These patterns were recorded in accordance with the optical magnetic field modulation method used in the conventional optical disk device while accurately managing the head position with a servo writer used in the conventional magnetic disk device. An overview of the positioning area 501 after the writing is shown in the lower part of FIG.

Here, the light spot 512 and the magnetic head 5
Even if 13 is at an arbitrary position, the width of the pattern written in these areas (width in the direction perpendicular to the direction of the information track 511) so that the patterns written in the synchronization area 503 and the track code area 505 can be detected. To
Adjust so as to be approximately equal to the track interval. The servo pattern 50 to be written in the track servo area 506
The width of 7 to 510 is adjusted to be smaller than the track interval. This is because the width of the magnetoresistive element of the magnetic head 513 to be used (the width in the direction perpendicular to the direction of the information tracks 511) is smaller than the interval between the information tracks 511, and the width of the servo patterns 507 to 510 is substantially reduced. Equal to the width of the magnetic head 513 or the magnetic head 51
By making the width smaller than 3, the dead zone when a track error signal is generated by the magnetic head 513 can be eliminated. The relationship between the widths of the servo patterns 507 to 510 and the width of the magnetic head 513 is the same as in the conventional magnetic disk drive. In this embodiment, since the magnetic head 513 having a width of 0.4 μm is used, the servo patterns 507 to 510 are used.
Was also adjusted to approximately 0.4 μm. However, when recording the servo patterns 507 to 510, the positioning area 50
The servo patterns 507 to 507-5 are set to be smaller than the laser power at the time of recording other patterns to be recorded in No. 1.
The width of the magnetic head 513 was controlled to be substantially equal to the width of the magnetic head 513.

(Optical Head Positioning Apparatus) Next, an apparatus (first positioning apparatus) for causing the light spot 512 to follow the information track 511 based on the pattern recorded in the positioning area 501 by the above means will be described.

In a conventional optical disk apparatus for recording / reproducing a magneto-optical recording medium, the phenomenon that the polarization plane of the reflected light from the recorded mark rotates by θk with respect to the polarization plane at the time of incidence, and the recorded mark Information is reproduced by utilizing the phenomenon that the polarization plane of reflected light from other sources rotates by −θk with respect to the polarization plane at the time of incidence. The rotation angle θk of the polarization plane is called a Kerr rotation angle and is one of the magneto-optical effects. The optical system for detecting the rotation of the polarization plane includes a Wollaston prism 111, a condenser lens 112, and photodetectors 113 and 114 shown in FIG. The detector 113 performs a photoelectric conversion and outputs a magneto-optical signal 115. On the other hand, the detector 114 similarly performs the photoelectric conversion, and
Is output. The differentiator 117 generates a magneto-optical signal 118 which is a difference between the magneto-optical signal 115 and the magneto-optical signal 116. The amplitude of the magneto-optical signal 118 generated in this manner changes in accordance with the rotation angle θk or −θk of the polarization plane.
Was used to reproduce the recorded information.

On the other hand, in the present invention, a track following error signal is generated from the magneto-optical signal 118 which has been conventionally used for reproducing information. Then, based on the track following error signal, a light spot 512 is formed as shown in FIG.
Follow 1 In order to accurately generate the track following error signal of the head, the positioning area 501 shown in FIG.
It is necessary to accurately detect each pattern recorded in the pattern. The magneto-optical recording medium 143 is rotated at a substantially constant rotation speed by a rotation motor (not shown), but the rotation speed slightly fluctuates with time due to the wow and flutter of the rotation motor. Therefore, in order to accurately detect the pattern recorded in the positioning area 501, a synchronization signal 133 synchronized with the rotation of the magneto-optical recording medium 143 is generated, and based on the synchronization signal 133, the synchronization area 133 is generated.
The pattern recorded in No. 1 must be detected. In order to generate the synchronization signal 133, the positioning area 501 is required.
, A target signal synchronized with the rotation of the magneto-optical recording medium 143 is generated, and the synchronization signal 133 is synchronized with the target signal.

The recording synchronization pulse generation circuit 125 in FIG.
Is a circuit for generating the target signal. As shown in detail in FIG. 3, the binarizing circuit 350 and the edge position detecting circuit 3
52, a synchronization signal pull-in position detection circuit 303. FIG.
The schematic diagram of the information mark in the middle is the synchronization pattern 515, the track code start pattern 516, and the servo patterns 507 to 510 shown in FIG. The signal waveform shown in the lower part of FIG. 3 is a timing chart of a signal generated by the recording synchronization pulse generation circuit 125 when the light spot 512 moves on the following path 208. First, the magneto-optical signal 118 whose amplitude varies according to the rotation angle θk or −θk of the polarization plane is binarized by a binarization circuit at a slice level indicated by a broken line in the drawing, and is converted into a binarization signal 351. You. The edge position detection circuit 352 outputs the recording synchronization pulse 126 based on the binary signal 351. The rising edge of the pulse included in the recording synchronization pulse 126 substantially coincides with the rising or falling edge position of the binarized signal 351, and the synchronization signal 133 is generated based on the recording synchronization pulse 126. Since the width of the synchronization pattern 515 and the width of the track code start pattern 516 are substantially equal to the track interval, regardless of whether or not the trajectory 206 of the optical head 512 coincides with the information track 511, the synchronization pattern 515 and the synchronization pattern 515 are used in the recording synchronization pulse 126. A rising edge of the pulse appears at the edge position of the track code start pattern 516. The synchronization signal pull-in position detection circuit 303 always observes an interval in which no pulse exists in the pulse sequence of the recording synchronization pulse 126,
When the interval between the absences of the pulses becomes approximately nT, it is determined that the light spot 512 has passed through the erasing area 504, and the rotation of the magneto-optical recording medium 143 further proceeds, and the level is increased only while the light spot 512 is present in the synchronization area 503 next. The recording synchronization pull-in gate signal 127 which becomes "H" is output. However,
The recording format of the magneto-optical recording medium 143 is determined in advance so that the interval at which the pulse is absent is substantially nT, which appears only at the interval between the synchronization pattern 515 and the track code start pattern 516.

Referring to FIG. 1, at the time of information recording, a higher-level control device (not shown) sets recording / reproducing gate signal 142 to level "
H ”, and the multiplexer 128 outputs
At the time of recording, the recording synchronization pulse 126 is changed to the synchronization pulse 129.
, And outputs the synchronization pull-in gate signal 127 during recording as the synchronization pull-in gate signal 130.

As means for generating the synchronization signal 133, a conventionally used synchronization signal generation circuit (PLL circuit)
131 was used. The PLL circuit 131 operates only while the level of the synchronization pull-in gate signal 130 is “H”, that is,
In FIG. 3, only when the light spot 512 exists in the synchronization area 503, feedback is performed so that the rising edge of the synchronization signal 132 coincides with the rising edge of the synchronization pulse 129, and the synchronization signal 132 is transmitted to the magneto-optical recording medium 1.
Synchronize with the rotation of 43. The synchronization signal 133 output from the PLL circuit 131 is “H” and “H” of the synchronization signal 132.
L ″ is generated by inverting L ″, and the synchronization signal 133
Is also synchronized with the rotation of the magneto-optical recording medium 143. The rising edge of the synchronization signal 133 thus generated is
As shown in FIG. 3, it substantially coincides with the peak position of the magneto-optical signal 118.

On the other hand, in FIG.
Outputs the synchronization signal 133 as the sample clock 135 when the recording / reproduction gate signal 142 is "H", that is, when information is recorded. The multiplexer 136 outputs the magneto-optical signal 118 as the reproduction signal 137 when the recording / reproduction gate signal 142 is “H”.

The tracking error generation circuit 138 generates a tracking error signal 139 based on the reproduction signal 137 and the sample clock 135, that is, based on the magneto-optical signal 118 and the synchronization signal 133. As the tracking error generation circuit 138, a circuit similar to the conventional circuit can be used, and the principle of generating the tracking error signal will be briefly described below.

As shown in FIG. 3, the rising edge of the synchronizing signal 133 substantially coincides with the peak position of the magneto-optical signal 118. Therefore, the tracking error generation circuit 138
Samples the reproduced signal 137 sequentially at the rising edge of the sample clock 135, and outputs the servo patterns 507 and
08, or the peak amplitudes of the reproduced signals of 509 and 510 are calculated. When the values of these peak amplitudes are obtained, the tracking error signal 139 becomes the servo patterns 507 and 508.
Or the difference between the peak amplitudes of 509 and 510.

FIG. 4 is a diagram schematically showing the track following error signal obtained in this manner.
2 moves along the direction perpendicular to the direction along the information track 511 (the y-axis in the figure), the peak amplitude value of the reproduced signal 137 of the servo pattern 507 changes as shown in the peak amplitude waveform 400. I do. Similarly, 50
The peak amplitude values of the reproduced signal 137 at 8, 509, and 510 change as shown by the peak amplitude waveforms 401, 403, and 404, respectively. At this time, the tracking error signal 13
9 is as shown in the tracking error waveform 402 (the level is an arbitrary scale) as the difference between the peak amplitude waveforms 400 and 401, or the peak amplitude waveforms 403 and 40
As shown in the tracking error waveform 405 (the level is an arbitrary scale) as a difference of 4. The tracking error waveform 402 or 405 is used as the tracking error signal 139.
The tracking error generation circuit 1
38 is determined. For example, based on the detection result of the track code 517 in front of the track servo area 506, if the information track is an even-numbered information track, the tracking error waveform 40
2 and the tracking error waveform 405 for the odd-numbered information track.

Referring to FIG. 1, when the tracking error signal 139 is generated by the above-described means, the actuator 140 is attached to the tip of the swing arm 141 so that the tracking error signal 139 is reduced as in the conventional case. The position of the recording / reproducing head 102 is controlled.

(Magnetic Head Positioning Apparatus) Next, an apparatus (second positioning apparatus) for causing the magnetic head 105 to follow the information track 511 based on the pattern recorded in the positioning area 501 will be described. When the magnetic head 105 is caused to follow, each pattern recorded in the positioning area 501 is reproduced by the magnetic head 105, and the position of the magnetic head 105 is controlled based on a magnetic reproduction signal 119 obtained as a result. The preamplifier 120 amplifies the amplitude of the magnetic reproduction signal 119 so that the amplitude of the magneto-optical signal 118 and the amplitude of the magnetic reproduction signal 119 are substantially the same, and outputs the amplified signal as an amplified magnetic reproduction signal 121. Similar to the position control of the light spot 512, the synchronization pulse generation circuit 122 for reproduction reproduces a target for synchronizing the synchronization signal 132 output from the PLL circuit 131 based on the amplified magnetic reproduction signal 121 with the rotation of the magneto-optical recording medium. Generate a signal. The pattern recorded in the positioning area 501 is converted to a light spot 512.
The obtained signal waveform differs between the case of reproducing with the magnetic head 105 and the case of reproducing with the magnetic head 105. Therefore, in order to generate a target signal corresponding to the edge of the pattern, a separate synchronization pulse generation circuit is required.

FIG. 2 shows a synchronizing pulse generation circuit 122 during reproduction.
FIG. Reproduction synchronization pulse generation circuit 12
2 is a differentiating circuit 300, a zero-cross position detecting circuit 302
And a synchronization signal pull-in position detection circuit 303. The schematic diagram of the information mark in FIG. 2 is the synchronization pattern 5 shown in FIG.
15, a track code start pattern 516, and servo patterns 507 to 510, and the signal waveforms below them are timing charts of signals generated by the reproduction synchronizing pulse generation circuit 122 when the magnetic head 513 moves along the trajectory 206. It is. As shown in FIG. 2, since a pulse-like waveform is obtained at the edge position of each pattern in the amplified magnetic reproduction signal 121, the amplified magnetic reproduction signal 121 is differentiated by the differentiating circuit 300 and zero-crossed at the edge position. And generate a differential signal 301. The zero cross position detection circuit 302 extracts a zero cross position of the differential signal 301,
A reproduction synchronization pulse 123 is generated. The rising edge of the pulse included in the reproduction synchronization pulse 123 substantially coincides with the zero cross position of the differential signal 301. Regardless of whether or not the trajectory 208 of the magnetic head 513 coincides with the information track 511, the rising edge of the pulse appears at the edge position of the synchronization pattern 515 and the track code start pattern 516 in the reproduction synchronization pulse 123. The synchronization signal pull-in position detection circuit 303 is exactly the same as that included in the above-described recording synchronization pulse generation circuit 125. Similarly, the level becomes “H” only while the magnetic head 513 is in the synchronization area 503. The reproduction synchronization pull-in gate signal 124 is output.

On the other hand, at the time of reproducing information, a higher-level control device (not shown) outputs the recording / reproducing gate signal 142 at level "L" in FIG.
Outputs the synchronization pulse 123 during reproduction as the synchronization pulse 129 and the synchronization pull-in gate signal 124 during reproduction as the synchronization pull-in gate signal 130.

As described above, the PLL circuit 131 rises the synchronization signal 132 only while the level of the synchronization pull-in gate signal 130 is "H", that is, only when the magnetic head 513 is in the synchronization area 503. Feedback is applied so that the edge coincides with the rising edge of the synchronization pulse 129, and the synchronization signal 132 is synchronized with the rotation of the magneto-optical recording medium 143.

The multiplexer 134 outputs the synchronization signal 132 as the sample clock 135 when the recording / reproducing gate signal 142 is "L", that is, when reproducing information. On the other hand, the multiplexer 136 outputs the recording / reproduction gate signal 142
Is "L", the amplified magnetic reproduction signal 121 is output as the reproduction signal 137.

The operation of the tracking error generation circuit 138 is exactly the same as during recording. As shown in FIG. 4, even when the magnetic head 513 moves in a direction perpendicular to the direction along the information track 511 (the y-axis in the figure), the tracking error signal 139 indicates that the light spot 512 is on the y-axis. It becomes substantially equal to the tracking error waveforms 402 and 405 obtained when moving along.

The tracking error signal 1
When 39 is generated, the actuator 140 controls the position of the recording / reproducing head 102 attached to the tip of the swing arm 141 to position the magnetic head 513 so that the tracking error signal 139 is reduced as in the related art. .

The first control signal generator of the present invention has the above-described configuration and is mainly composed of a recording synchronization pulse generation circuit, a multiplexer, a PLL circuit, and a tracking error generation circuit. The second control signal generator mainly includes a simultaneous pulse generator for reproduction, a multiplexer, and a PL.
It comprises an L circuit and a tracking error generation circuit.

Although the information recording medium and the recording / reproducing apparatus of the present invention have been described above, the present invention is not limited to these. For example, in the above embodiment, an information recording medium using a perpendicular magnetic film as a magnetic layer was used as an information recording medium, but the present invention is also applicable to an information recording medium using an in-plane magnetic film as a magnetic layer. .

[0055]

According to the information recording medium of the present invention, since servo marks and management information are formed by using magnetic marks, a substrate to be used does not need to have a concavo-convex pattern, and flatness can be ensured over the entire medium. Thus, the slider on which the optical head and the magnetic head are mounted can be floated in a stable state. Therefore, even if the slider is run on the information recording medium with a low flying height, head crash hardly occurs, so that it is possible to reliably reproduce the leakage magnetic field from the minute recording mark, and to increase the recording density. Can be realized.

The recording / reproducing apparatus of the present invention positions an optical head, a recording magnetic head and a reproducing magnetic head on desired tracks based on a magneto-optical signal and a leakage magnetic field from a magnetic mark formed on an information recording medium. Therefore, the present invention is extremely suitable as a recording / reproducing apparatus for the information recording medium of the present invention.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a recording / reproducing apparatus according to the present invention.

FIG. 2 is a diagram illustrating a configuration of a reproduction synchronization pulse generation circuit, a schematic diagram of a management information mark group formed on an information recording medium, and a reproduction signal when the mark group is reproduced using a magnetic head. is there.

FIG. 3 is a diagram illustrating a configuration of a recording synchronization pulse generation circuit, a schematic diagram of a management information mark group formed on an information recording medium, and a reproduction signal when the mark group is reproduced using an optical head. is there.

FIG. 4 is a diagram for describing generation of a tracking error signal using an optical head and a magnetic head.

FIG. 5 is a plan view of an information recording medium according to the present invention and a diagram showing a magnetic mark pattern formed in a positioning area.

FIG. 6 is a schematic sectional view of an information recording medium according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 substrate 101 recording film 102 recording / reproduction head 103 slider 104 recording magnetic coil 105 reproduction magnetic head 106 semiconductor laser 110 solid immersion lens 122 reproduction synchronization pulse generation circuit 125 recording synchronization pulse generation circuit 128 multiplexer 131 synchronization signal generation circuit 143 Magneto-optical recording medium 501 Positioning area 502 Data storage area 503 Synchronous area 504 Erase area 505 Track code area 506 Track servo area 507-510 Servo pattern 511 Information track 515 Synchronous pattern 516 Track code start pattern 517 Track code 518 Data pattern

Continuing from the front page (72) Inventor Teruaki Takeuchi 1-1-88 Ushitora, Ibaraki-shi, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Nobuyuki Inaba 1-188 Ushitora, Ibaraki-shi, Osaka Hitachi Maxell shares In-company (72) Inventor Fumiyoshi Kirino 1-88 Ushitora, Ibaraki-shi, Osaka F-term in Hitachi Maxell Co., Ltd.F-reference (reference)

Claims (11)

[Claims] 1. An information recording medium comprising: a magnetic layer on a flat substrate, wherein information is recorded by applying light and an external magnetic field to a data area of the magnetic layer; An information recording medium, wherein the servo pattern is formed as a magnetic mark on the magnetic layer. 2. The information recording medium according to claim 1, wherein said magnetic layer is a perpendicular magnetic recording film. 3. The information recording medium according to claim 1, wherein the magnetic mark is recorded by an optical magnetic field modulation method. 4. The magnetic mark includes a servo pattern for applying servo of a reproducing magnetic head, and the servo pattern is formed such that the width of the servo pattern in the track width direction is equal to or less than the reproducing magnetic head width. The information recording medium according to claim 1, wherein the information is recorded. 5. A recording / reproducing apparatus for recording / reproducing an information recording medium, wherein the information recording medium includes a magnetic layer on a flat substrate, and a servo pattern and management information are recorded as a magnetic mark on the magnetic layer. An optical head for irradiating the information recording medium with light during information recording, a recording magnetic head for applying a recording magnetic field to the information recording medium, and a magnetic layer for reproducing information. A reproducing magnetic head for detecting a leakage magnetic field from a recorded magnetic mark, and a first positioning device for positioning the optical head and the recording magnetic head on a desired track based on a magneto-optical signal from the magnetic mark When information is reproduced, a magnetic field for leakage from the magnetic mark is detected by a reproducing magnetic head to position the reproducing magnetic head on a desired track. A recording / reproducing device, comprising: a second positioning device. 6. A first positioning device, comprising: a detector for detecting light from a magnetic mark; and a position information of an optical head and a recording head from a detection signal from the magnetic mark detected by the detector. A first control signal generator for obtaining a control signal for obtaining and arranging the optical head and the recording head at desired track positions; and positioning the optical head and the recording magnetic head at desired track positions based on the control signals. 6. The recording / reproducing apparatus according to claim 5, further comprising: a first actuator for driving the recording / reproducing apparatus. 7. The second positioning device obtains position information of the reproducing magnetic head from a signal from a magnetic mark detected by the reproducing magnetic head, and arranges the reproducing magnetic head at a desired track position. And a second actuator for driving the reproducing magnetic head to a desired track position based on the control signal from the second control signal generator. The recording / reproducing apparatus according to claim 5 or 6, wherein 8. The information processing apparatus according to claim 5, further comprising a slider flying above the information recording medium, wherein the slider includes the optical head, the recording magnetic head, and the reproducing magnetic head. A recording / reproducing apparatus according to claim 1. 9. The reproducing magnetic head according to claim 5, wherein the reproducing magnetic head is an MR head or a GMR head.
The recording / reproducing device according to any one of claims 1 to 4. 10. The recording / reproducing apparatus according to claim 5, wherein the optical head includes a solid immersion lens. 11. A head positioning method for positioning an optical head, a recording magnetic head, and a reproducing magnetic head at predetermined track positions on an information recording medium, wherein a magnetic layer is formed on a flat substrate as the information recording medium. An information recording medium in which a servo pattern and management information are recorded as magnetic marks on the magnetic layer, and at the time of information recording, the management information mark group is irradiated with a laser beam so as to generate magneto-optical information from the management information mark group. Signals are detected, and the positions of the optical head and the recording magnetic head are controlled based on the detected magneto-optical signals. When information is reproduced, the leakage magnetic field from the management information mark group is detected using the reproducing magnetic head. And a head positioning method for controlling the position of the reproducing magnetic head based on the detected signal.