JPH07272342A - Composite recording medium - Google Patents

Abstract

PURPOSE:To improve traveling stability by providing a composite recording medium with a nonmagnetic intermediate layer to flatten grooves for tracking or the ruggedness by reflection rugged pits, thereby preventing reflection thereof to the ruggedness or thickness on the front surface of a magnetic recording layer. CONSTITUTION:This composite recording medium is provided with the nonmagnetic intermediate layer 3 as a flattening layer for lessening the influence of the rugged bit arrays or the ruggedness of the grooves between a magnetic recording part 2 and an optical recording part 4. As a result, the track pitch of the magnetic recording layer 2 is independently optimized without being limited by the track pitch of the optical recording part 4. Designing by taking advantage of the characteristics of the respective recording systems is made possible. More particularly, the magnetic recording is easier to increase the line density than optical recording and, therefore, the degradation in S/N is compensated by correspondingly widening the tracks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium for realizing high density composite recording by magnetic recording and optical recording with high reliability.

[0002]

2. Description of the Related Art In addition to conventional information mainly consisting of numerical values and characters, so-called multimedia-related information recording amount including information such as still images, moving images and voices is rapidly increasing. Along with this, the importance of a high-density recording disk having a large capacity and a high transfer rate and a high access rate is further increasing. Against this background, magnetic disks typified by hard disks and floppy disks, and three types of optical disks for reproduction only, write-once, and rewritable are recording disks with remarkable technological progress. However, magnetic disks and optical disks have different characteristics, and are currently used properly according to the application. The optical disc is superior in terms of track density and the areal density is higher than that of the magnetic disc, but magnetic recording is higher and transfer rate is faster in terms of linear density. A recording medium capable of combined recording of optical recording and magnetic recording is conceivable as a recording medium that can be manufactured at low cost by utilizing the characteristics of both.

As one example thereof, a composite recording medium by composite recording of magneto-optical recording and magnetic recording is disclosed in Japanese Patent Application No. 5-11613.
9 was proposed. In this composite recording medium, a magneto-optical recording portion and a magnetic recording portion are formed in this order on a transparent substrate, and magneto-optical recording is performed by light irradiation from the transparent substrate side and magnetic field application from the magnetic recording portion side. At the same time, the magnetic recording can be performed by the magnetic head from the magnetic recording portion side. Here, since the magneto-optical recording layer and the Curie point of the magnetic recording layer and the coercive force at room temperature and high temperature are appropriately set, each recorded information is not destroyed regardless of whether they are adjacent to each other. Absent. Tracking at the time of optical recording of this composite recording medium is performed by detecting grooves or concave / convex pit rows formed on the surface of the transparent substrate on the side of the optical recording portion by the light incident from the opposite surface side. However, in addition to the thin thickness of the optical recording portion, especially in the case of magneto-optical recording or phase change recording formed by the vacuum film forming technique, the unevenness on the substrate is almost directly reflected on the surface, so that the unevenness of the grooves and pits is generated. ,
It is reflected on the surface of the optical recording part. As a result, the bottom surface of the magnetic recording portion formed on the magnetic recording portion becomes uneven, and the surface of the magnetic recording portion becomes uneven, and the thickness of the magnetic recording portion becomes uneven. The surface unevenness of the magnetic recording portion causes noise during magnetic recording, resulting in a decrease in S / N. Further, since the thickness of the magnetic recording layer is generally optimized depending on the recording wavelength to be used and the amount of the perpendicular magnetic field component, the nonuniformity of the thickness causes deterioration of the recording / reproducing performance.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a recording / reproducing performance of a composite recording medium in which an optical recording portion such as the above-described magneto-optical recording and a magnetic recording portion are formed in this order on one side of a transparent substrate. It is another object of the present invention to provide a highly reliable recording medium. More specifically, it is intended to reduce the unevenness of the surface of the magnetic recording part and the fluctuation of the thickness caused by the tracking groove and the uneven pit row on the transparent substrate, and improve the recording / reproducing performance of the magnetic recording part.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to form a pit row for tracking or a groove for tracking on one surface of a transparent substrate, on which an optical recording section is provided. There is a magnetic recording portion on the upper surface of the non-magnetic intermediate layer, the thickness of the non-magnetic intermediate layer is thicker than the depth of the pit row or the groove, and the unevenness of the pit row or the groove is the non-magnetic intermediate layer. This is achieved by a composite recording medium that is flattened to the extent that it does not appear on the surface of the intermediate layer.

In the composite recording medium of the present invention, since the magnetic recording layer and the optical recording layer are arranged in the thickness direction of the medium, the recording capacity per surface can be increased accordingly. And, by providing a non-magnetic intermediate layer between the optical recording portion and the magnetic recording portion, the non-magnetic intermediate layer for flattening the irregularities on the surface of the optical recording portion on the magnetic recording portion side caused by the concave-convex pit row or groove for tracking Since the unevenness for tracking does not reach the surface of the optical recording part or the bottom surface of the magnetic recording part, it is possible to minimize unevenness and thickness variation on the surface of the magnetic recording part, resulting in more reliable recording. It becomes possible to provide playback performance.

Since the composite recording medium according to the present invention basically has the recording portion formed on one side, there is no increase in cost due to the bonding unlike the bonded type optical disk.
Moreover, there is no increase in weight or thickness due to bonding. Nevertheless, since the magnetic recording layer and the optical recording are formed so as to overlap each other in the thickness direction, the recording area is equivalent to that of the double-sided type and the recording capacity can be substantially equal to that of the double-sided type. Further, the concave-convex pits and grooves on the substrate can be easily formed at a low cost by the same method as that for the optical disk, that is, injection molding using a stamper or the 2P method.

By providing a non-magnetic intermediate layer between the magnetic recording portion and the optical recording portion of the present invention as a flattening layer for reducing the effect of the uneven pit row or the unevenness of the groove, the track pitch of the magnetic recording layer is increased. Since it can be optimized independently without being limited by the track pitch of the optical recording unit,
It is possible to design by utilizing the characteristics of each recording method. In particular, magnetic recording makes it easier to increase the linear density than optical recording, so by increasing the track width accordingly,
It is possible to compensate for the decrease in S / N. Further, since no unevenness appears on the surface of the magnetic recording layer, there is no concern about running stability of the magnetic head. That is, by making the thickness of the non-magnetic intermediate layer thicker than the depth of the pit rows and the grooves formed for tracking, unevenness does not appear on the surface of the non-magnetic intermediate layer and the surface is flattened. It has become. The optical recording section in the present invention includes Japanese Patent Application No. 5-11
In addition to the magneto-optical recording layer described in the specification 6139, a phase change recording layer, a write-once recording layer using an organic dye, a read-only recording layer using concave and convex pits, and the like can be adopted.

In the optical recording section, a magneto-optical recording layer or a phase change type optical recording layer is used if it is desired to make it rewritable, and a write-once recording layer made of an organic dye is used for reproduction only if it is desired to be write-once. If desired, the read-only recording layer may be selected. Further, it is also possible to make a hybrid type optical recording unit by combining these. The magnetic recording layer formed on the optical recording portion via the non-magnetic intermediate layer is not particularly limited, and various conventionally known magnetic recording layers can be used. For example, it is a coating film in which ferromagnetic fine powder is dispersed with a binder resin, a ferromagnetic metal thin film formed by a vapor deposition method or a sputtering method, and the like. As the non-magnetic intermediate layer provided between the optical recording portion and the magnetic recording layer,
Specifically, UV curable resin or thermosetting resin spin coating method, reverse roll method, doctor blade method,
It is a coating layer or the like that is hardened after being applied by a method such as a coil bar method. Among them, particularly preferable is that the UV-curable resin layer formed by the method of spin-coating the UV-curable resin and then UV-curing is simple and easy to be in-line. As the material of the transparent substrate used in the composite recording medium of the present invention, polycarbonate, amorphous polyolefin, glass and the like used in ordinary magneto-optical recording media are suitable. Other, P
A transparent resin such as MMA can also be used. It is desirable to use a material having a small birefringence, a high transmittance, a low hygroscopicity, and less warpage or deformation. Specifically, it is preferable to use polycarbonate, glass, PMMA, APO or the like. In particular, polycarbonate is suitable as a transparent substrate in the composite recording medium of the present invention because it has excellent injection moldability, is less likely to warp due to moisture absorption, and is inexpensive.

In the composite recording medium of the present invention, a pit row for tracking or a groove for tracking is formed on one surface of the transparent substrate. The formed surface is the surface opposite to the light incident side, on which the recording portion is formed. When the push-pull method is adopted as the tracking method, the optimum depth is generally λ /
It is given by (8n). Here, λ is the wavelength of the light source used, and n is the refractive index of the transparent substrate. When an information signal is also detected by a reflection signal of uneven pits like a CD (Compact Disc), a value intermediate between pit depth λ / (4n) that maximizes the signal modulation is adopted. . The pit row or groove for tracking is formed by a general method for manufacturing an optical disc. That is, tracking grooves and pit rows are cut with a laser beam on a quartz glass master coated with a photoresist, and after development, this is transferred by nickel plating to produce a stamper. Next, using this, polycarbonate and PM
It is obtained by replica transfer by injection molding to a transparent plastic such as MA. When a glass substrate is used as the transparent substrate, the 2P method or the direct cutting method is often used.

For tracking as described above, the optical recording portion is formed on the transparent substrate on which the pit row or groove is formed. The optical recording portion is generally formed by sputtering in the case of rewritable magneto-optical recording or phase change type optical recording, and the reflection layer is formed by vapor deposition or sputtering in the case of reproduction only. In the case of dye type write-once type optical recording, it is general that the reflective layer is vapor-deposited or sputtered after the organic dye is applied.

The thickness of the optical recording portion varies depending on each recording system. For example, a four-layer type magneto-optical recording layer will be described as an example. -80 nm, the second dielectric layer is 10-6
0 nm, the magneto-optical recording layer is preferably 20 to 40 nm, and the first dielectric layer is preferably 80 to 130 nm. By doing this,
Of the incident light, the light not absorbed by the magneto-optical recording layer
The reflected light from the reflective layer can efficiently contribute to recording, and the enhancing effect of the dielectric layer can be enhanced. Also, by having a sink function that appropriately releases heat, it is possible to minimize heat interference and bleeding in the recording pit. However, these optimum thicknesses vary depending on the wavelength of the laser light and the like. The above example is an example of a wavelength of 780 to 830 nm.

A non-magnetic intermediate layer is formed on the optical recording portion. After the ultraviolet curable resin or the thermosetting resin is applied by spin coating, reverse roll, doctor blade method, coil bar method or the like as described above. ,
Those formed by curing by a method such as ultraviolet irradiation or hot air blowing are also effective for the optical recording portion having such a structure.

At that time, in order to enhance the weather resistance of the reflective layer of the magneto-optical recording layer, it is necessary to pay attention to the point of processing in a nitrogen atmosphere.

The thickness of the non-magnetic intermediate layer in the composite recording medium of the present invention is at least thicker than the irregularities formed on the surface of the optical recording portion, reflecting the tracking grooves and the reflection pits formed on the transparent substrate. There is a need to. It is desirable that the depth of the tracking groove or the reflection pit formed on the transparent substrate is thicker than the depth itself, and more desirably, twice or more. If it is thinner than this, it becomes impossible to effectively alleviate the irregularities on the surface of the optical recording portion by the above method. Usually, with the coating by the above-mentioned coating method, a non-magnetic intermediate layer having a thickness in the range of 0.1 μm to several hundreds μm can be easily produced. If it is too thick, the material cost will be high, so it is usually better to set it to 20 μm or less.

For the magnetic recording portion in the composite recording medium of the present invention, a usual magnetic recording material currently used for magnetic tapes and magnetic disks can be used. That is, it is a coating film in which ferromagnetic particles are dispersed in a binder resin (binder) composed of a vinyl chloride resin, a polyurethane resin, a curing agent, or a thin film formed by a vacuum film forming technique such as sputtering or vacuum deposition. is there. The coating type ferromagnetic fine particles include needle-shaped or rice-shaped metallic powder, Co-doped γ-Fe ₂ O ₃ , Co-deposited γ-Fe ₂ O ₃ , γ-Fe.
₂ O ₃ or hexagonal plate-shaped Ba ferrite is used.

FIG. 1 is a cross-sectional view of essential parts showing an example of a composite recording medium 100 of the present invention. Here, 105 is a transparent resin substrate, and 108 is a groove for tracking. Reference numeral 15 denotes a light incident direction, and the magnetic head for magnetic recording is installed on the surface opposite to the light incident side. Transparent substrate 105
An optical recording portion 104, a non-magnetic intermediate layer 103, and a magnetic recording portion 36 are formed in this order on the top. Magneto-optical recording unit 10
In No. 4, a first dielectric layer 131, a magneto-optical recording layer 130, a second dielectric layer 129, and a reflective layer 128 are formed in this order from the substrate side. Since the non-magnetic intermediate layer 103 of the present invention has a thickness sufficiently thicker than the depth of the tracking groove 108, the magneto-optical recording portion 104 (further In detail, the unevenness on the surface of the reflective layer 128 on the magnetic recording portion side) can be flattened on the non-magnetic intermediate layer 103 (interface with the magnetic recording portion side). As a result, the magnetic recording portion 36 can have a flat surface and a uniform thickness.

In this example, in the magnetic recording portion 36, the underlayer 27, the magnetic recording layer 26, and the protective layer 32 are formed on the nonmagnetic intermediate layer 103 by the sputtering method. As the magnetic recording layer 26, CoNiCr, CoCrTa, Co
PtCr, Co, CoNi, CoCr, etc. are used. Further, as the underlayer 27, Cr or the like is used for the purpose of improving magnetic characteristics and corrosion resistance. Furthermore, the underlayer 27
A plating layer such as NiP may be provided between the nonmagnetic intermediate layer 103 and the nonmagnetic intermediate layer 103. As the protective layer 32, a hard protective layer such as diamond like carbon (DLC) is often used. The DLC can also be formed by the CVD method. By providing the lubricating layer 35 on the protective layer 32 by a method such as spin coating, sliding with the magnetic head can be smoothly performed.

The thickness of the magnetic recording layer 32 varies depending on the recording wavelength, but is generally about 0.05 to 5 μm. If it is too thin, the leakage magnetic flux at the time of reproduction becomes small, and a sufficient reproduction output cannot be obtained. On the other hand, if it is too thick, the recording magnetization forms a rotational magnetization mode, which makes it impossible to obtain a high output, which is not preferable. As described above, the thickness distribution of the optical recording portion, the non-magnetic layer intermediate layer and the magnetic recording portion formed on the transparent substrate of the composite recording medium of the present invention is not particularly limited, and depending on each recording method, The optimization described above may be performed.

There is no particular limitation on the magnetic head or the optical pickup used in the recording method using the composite recording medium of the present invention. One of the advantages of the composite recording medium of the present invention is that a conventionally known one can be used as it is. Is. The magnetic head is a normal magnetic recording head in which a coil is wound around a soft magnetic core. Further, in the case of combined recording of magneto-optical recording and magnetic recording, a form in which the magnetic head for magneto-optical recording and the magnetic head for magnetic recording are integrally incorporated in one magnetic head slider is used during magneto-optical recording and magnetic recording. The head control system at this time can be simplified, and highly accurate positioning can be performed.

As the optical pickup, an optical pickup using a normal semiconductor laser used for optical recording as a light source can be used, but its function is focusing and tracking. In the case of composite recording with optical recording, a recording / reproducing function of an optical recording signal is added to this. Also, it has a function of reproducing wobbling signals of the reflection pits and the tracking groove, if necessary. Further, there are various focusing and tracking methods, which are not particularly limited and are selected according to their respective applications.

The structure of the composite recording medium of the present invention is shown in FIG. 2 which is a cross-sectional view of the main part, and the positions of the optical pickup and the magnetic head when recording / reproducing using the composite recording medium of the present invention. The features of the composite recording medium of the present invention will be specifically described with reference to the layout diagram of FIG. 3 showing the servo tracking system for showing the relationship.

The composite recording medium 1 of the present invention shown in FIG.
The optical tracking groove 8 is transferred to one side of the transparent substrate 5 by injection molding using a stamper formed by mastering similar to that of a normal optical disc.

The shape of this groove is given by the optimum depth of λ / (8n), where λ is the wavelength of the light source and n is the refractive index. When a 780 nm semiconductor laser is used as the light source and polycarbonate is used as the transparent substrate, the optimum depth is about 0.13 μm. The width of the land is 0.4 when optically recorded on the land (the flat surface opposite to the incident light).
˜0.6 μm. Next, on the same surface side as this, the optical recording part 4 is formed into a film by the sputtering method. Since the optical recording portion 4 is extremely thin and is formed by the sputtering method as described above, the optical recording portion 4 is formed of a coating film such as an ultraviolet curable resin as a flattening layer so as not to reflect the unevenness of the optical tracking groove 8. The non-magnetic intermediate layer 3 is 1 to 10 μm.
It is formed by spin coating in a nitrogen atmosphere in a thickness of about m and then irradiating it with ultraviolet light to cure it. Further thereon, a magnetic coating solution in which a needle-shaped magnetic metal material is dispersed in a binder containing polyurethane and vinyl chloride resin as a main component is applied by the same spin coating method and thermally cured to form a magnetic recording layer 2. To 0.1
It is formed with a thickness of ˜3 μm.

Here, the width of the magnetic recording track 6 does not necessarily have to match the width of the optical recording track 7, and can be optimized according to each recording method. The magnetic recording tracks 6 are separated by a guard band 9. When adopting the azimuth recording method, such a guard band can be omitted.

The composite recording medium 1 created in this way
On the other hand, as shown in FIG. 3, the optical pickup 14 is arranged on the transparent substrate 5 side, and the magnetic head slider 10
Is arranged on the recording surface side.

When the optical recording section is a magneto-optical recording layer,
In the optical pickup 14, the emitted light from the semiconductor laser is the same as in the ordinary magneto-optical recording pickup.
It is appropriately shaped and polarized. The laser light 15 passes through the objective lens from the transparent substrate side of the composite recording medium 1,
The reflected light is irradiated onto the optical recording unit and detected by the optical pickup 14. As a tracking method, various generally known methods can be used. In the push-pull method, which is one of them, a tracking signal is obtained by detecting a push-pull signal from a groove with a two-division photodetection system. To be

The optical pickup 14 and the magnetic head slider 10 are connected by an interlocking arm 22, as shown in FIG.
Positioning in the mechanical radial direction is performed by open loop control. This point is the same as the conventional magnetic field modulation overwrite type magneto-optical disk drive. Further, fine adjustment tracking is performed as follows. A tracking error signal is detected by the tracking error detection system 18 from the reflected light detected by the optical pickup 14, and the optical pickup moving mechanism 16 performs tracking on the optical recording track 7 through the tracking servo 19 for optical pickup. The fine tracking on the magnetic recording track 6 is performed by transmitting a tracking error signal from the tracking error detection system 18 to the tracking servo 20 for the magnetic head slider and controlling the magnetic head slider moving mechanism 17.

In the off-track, the composite recording medium 1 is chucked on the motor shaft of the spindle motor 24 by the chucking plate 25.
It is caused by an eccentric component generated when chucking is performed, deformation of the optical tracking groove 8 due to distortion of the composite recording medium 1 itself, and the like. Tracking to an optical recording track is performed by an open loop coarse adjustment and an optical pickup movable mechanism 1 incorporating an optical pickup 14.
The feature of the combination of 6 is the same as that of the usual magneto-optical recording. In addition, the magnetic head slider 10
The interlocking arm 22 is similar to the magnetic field modulation overwrite type magneto-optical drive in that it is connected to the optical pickup 14 for coarse tracking, but in the case of magneto-optical recording, positioning of the recording point is performed optically. The magnetic field applied during magneto-optical recording is determined by the laser spot by the pickup 14, and may be applied over a wide range (for example, 1 mmφ) that is incomparable to magnetic recording, and therefore the magnetic head slider 10 is positioned. Is also very coarse and can be used. However, the recording on the composite recording medium 1 in the present invention performs not only optical recording but also magnetic recording, and extremely high accuracy is required for positioning on the magnetic recording track 6. The accuracy required for magnetic recording cannot be obtained only by the rough tracking described above, and magnetic recording at a high track density is impossible. In the present invention, in addition to the coarse tracking, the optical tracking groove 8
By providing a fine adjustment tracking system to the magnetic recording track 6 by the tracking error signal obtained from
It enables magnetic recording at high track density. Here, a method of directly feedback controlling the coarse adjustment tracking drive unit 21 by a tracking error signal from the tracking error detection system 18 can be considered, but the optical pickup 14 and the magnetic head slider 10, the interlocking arm 22, the coarse adjustment positioning are performed. It is necessary to integrally control even the carriage 23 for high speed, which is not realistic considering these inertial forces and the required servo frequency, and separate fine adjustment tracking is required for optical recording and magnetic recording.
When performing optical recording / reproduction and magnetic recording / reproduction at the same time,
It is necessary to perform both fine adjustment tracking at the same time, but when only optical recording / reproducing is performed, the magnetic head slider 10
Fine tuning tracking is not required.

[0030]

EXAMPLES The novel features of the composite recording medium of the present invention will be explained more concretely by the following examples.

Example 1 A composite recording medium 100 having a layer structure as shown in FIG. 1 was prepared under the following conditions.
A tracking groove 108 was formed on a glass substrate 105 having a thickness of 1.2 mm and an outer diameter of 3.5 inches by a dry etching method at a track pitch of 1.6 μm. Magneto-optical recording is 1.
Magnetic recording is performed at a width of 4.
This was performed by providing a guard band 109 having a width of 0.5 μm on the track portion 106 having a thickness of 3 μm. Each 4 in the magneto-optical recording unit 104
The layer thickness and materials are as follows. Reflective layer 128 Al 75 nm Second dielectric layer 129 Si ₃ N ₄ 40 nm Magneto-optical recording layer 130 TbFeCoCr 25 nm First dielectric layer 131 Si ₃ N ₄ 110 nm In order to optimize the corrosion resistance and heat conduction, the reflective layer 128 is optimized. , Ti was added at 2 at%. Then, the first dielectric layer 131 and the magneto-optical recording layer 13 are formed on the glass substrate 105.
0, the second dielectric layer 129 and the reflective layer 128 in this order
The dielectric 131 layer and the second dielectric layer 129 are made of reactive RF.
The magneto-optical recording layer 130 was deposited by DC sputtering of an alloy target, and the reflective layer 128 was deposited by DC sputtering to form the optical recording portion 104.

As the non-magnetic intermediate layer 103, an ultraviolet curable resin was spin-coated in a nitrogen atmosphere and then cured by ultraviolet to form an ultraviolet curable resin film having a thickness of 7 μm. The magnetic recording part 36 has a layered structure including the following four layers. Lubricating layer 35 Fluorine-based lubricant Fomblin AM2001 3 nm Carbon protective layer 32 Diamond-like carbon 30 nm Magnetic recording layer 26 CoPtCr 50 nm Underlayer 27 Cr 300 nm

Then, each of the above layers is formed on the metal reflection layer of the magneto-optical recording portion by forming the underlayer 27, the magnetic recording layer 26 and the carbon protective layer 32 by DC magnetron sputtering, and further, the carbon protective layer. A lubricating layer 35 was spin-coated on 32 to form a magnetic recording portion 36.

The Curie temperature Tc of the magneto-optical recording layer 130 and the magnetic recording layer 26, the coercive force Hc (r) at room temperature (23 ° C.) for magnetic recording, and the temperature 200 ° C. for magneto-optical recording.
The coercive force Hc (h) at was as follows.

The Curie temperature and the coercive force were measured by a vibrating sample magnetometer (VSM). Magneto-optical recording layer 130 TbFeCoCr Curie temperature Tc: 200 ° C. Coercive force Hc (r): 9 Oe Coercive force Hc (h): 0.1 Oe or less Magnetic recording layer 26 CoPtCr Curie temperature Tc: 500 ° C. or higher Coercive force Hc (r): 1.8 Oe Coercive force Hc (h): 1.6 Oe

Recording and reproduction were performed on this composite recording medium by using a magneto-optical recording magnetic head 33 and a magnetic recording magnetic head 34 whose principal part cross-sectional view is shown in FIG. The magneto-optical recording magnetic head 33 is incorporated in the magnetic head slider 10. The magnetic head slider 10 was mounted on a Whitney type flexure, and was allowed to run in contact with the surface of the magnetic recording layer.
As the magnetic head 34 for magnetic recording, a ring-type magnetic head having a gap length of 0.3 μm was used and used for both recording and reproduction.
Further, the magneto-optical recording magnetic head 33 employs a system in which a coil is wound around the main magnetic pole and the magnetic flux is circulated from the auxiliary magnetic pole, and the substantial spacing between the tip of the main magnetic pole core and the magneto-optical recording layer 30 is It was set to 0.15 mm. The magnetic head slider 10 has a traveling direction of 4 mm and a radial direction of 3 m.
The magnetic head 33 for magneto-optical recording and the magnetic head 34 for magnetic recording are installed with a space of 2 mm.
At the time of tracking, as shown in FIG. 3, first, the coarse adjustment tracking drive unit 21 performed the coarse adjustment tracking to the target track, and then the fine adjustment tracking. In the fine adjustment tracking, as shown in FIG. 3 as well, the RF signal detected by the optical pickup 14 is detected as a tracking error by the tracking error detection system 18, and one is sent to the optical pickup tracking servo 19 and the optical pickup moving mechanism 16 is provided. Is controlled to perform tracking to the optical recording track 7, and the other one signal is sent to the magnetic head slider tracking servo 20 to control the magnetic head slider moving mechanism 17 to perform tracking to the magnetic recording track 6. I did.

Next, the following digital recording / reproducing was tried using this composite recording medium. Optical pickup 14
The laser light 15 emitted from the laser has a wavelength of 780 nm, and was focused by a lens while applying focus servo so as to focus on the magneto-optical recording layer 30 with optical power of 5 mW during recording and 0.7 mW during reproduction. The running speed of the disk was 1.2 m / s.

Overwriting type digital magnetic recording is performed for magnetic recording on the magnetic recording layer 36, and magnetic field modulation overwriting type digital recording is performed for magneto-optical recording on the magneto-optical recording unit 4. The recording / reproducing principle for stable magnetic recording and magneto-optical recording is apparent from the graph showing the correlation between temperature and coercive force in FIG. That, H _c of the magneto-optical recording layer 130 at room temperature, for sufficiently greater than H _c of the magnetic recording layer 26, does not already recorded information of the magneto-optical recording layer 130 is erased when the magnetic recording at room temperature. The Curie point of the magnetic recording layer 26 is the magneto-optical recording layer 130.
Sufficiently higher than the Curie point, and since it has a sufficiently high H _c than the recording magnetic field applied during the magneto-optical recording, even when the magneto-optical recording by irradiating a laser beam, a magnetic recording layer 2
It is said that there is no fear that the information recorded in 6 will be erased.

It was confirmed by the above method that both the magnetic recording layer 26 and the magneto-optical recording layer 30 could be stably recorded / reproduced, and even if recording / reproduction was repeated with various signal patterns, the quality of the other recording signal was deteriorated. It was possible to perform highly reliable recording and reproduction without any trouble. As a result, compared with the case of magneto-optical recording or magnetic recording alone, it is approximately 2
Double recording capacity could be secured, and double transfer rate was obtained by simultaneously performing magnetic recording and magneto-optical recording. Furthermore, when performing magnetic recording alone, the running speed is 12 m / s
As a result, a transfer rate 10 times that of magneto-optical recording was obtained. In addition, since the tracking of the magnetic recording is also performed by optically detecting the groove, the positioning can be performed with high accuracy, and the track density can be significantly increased.

[Embodiment 2] A composite recording medium was prepared under the same conditions as in Embodiment 1 except that the following coating type magnetic layer was formed on the non-magnetic intermediate layer as the magnetic recording portion. It was created. The following composition was kneaded and dispersed in a ball mill until uniform, to prepare a magnetic coating material. 1000 parts by weight of ferromagnetic metal fine powder (composition: Fe 96 wt%, Ni 4 wt%) (specific surface area: 45 m ² ) 97 parts by weight of vinyl chloride / vinyl acetate / maleic anhydride copolymer (400X110A, manufactured by Zeon Corporation) polyurethane resin 35 parts by weight (Nipporan N-2304, manufactured by Nippon Polyurethane Company) Polyisocyanate compound 75 parts by weight (Coronate L, manufactured by Nippon Polyurethane Company) 10 parts by weight carbon black (average particle size: 0.04 μm) Cr ₂ O ₃ 100 parts by weight (Average particle size: 0.33 μm) Amyl stearate 100 parts by weight Butoxyethyl stearate 15 parts by weight Methyl ethyl ketone 1740 parts by weight Cyclohexanone 1160 parts by weight

As a coating liquid for the non-magnetic intermediate layer, a composition in which 1000 parts by weight of fine Ti powder was used in place of the above ferromagnetic metal powder was kneaded and dispersed in the same manner as above. This coating liquid was applied by a doctor blade method to a thickness of 10 μm and dried so that the irregularities of the optical tracking groove were not reflected on the surface of the magnetic recording layer. Next, the above magnetic paint was applied and dried to obtain a magnetic recording layer having a thickness of 0.4 μm. The surface of this coating type magnetic recording layer was burnished with a # 8000 polishing tape to remove fine defects on the surface.

The Curie temperature T _c of the coating type magnetic recording layer,
Coercive force H at room temperature (23 ℃) for magnetic recording
_{The c} (r) and the coercive force H _c (h) at the temperature of 200 ° C. for magneto-optical recording were as follows. The magneto-optical recording layer had the same Tc and Hc as in Example 1. Curie temperature Tc: 700 ° C. or higher Coercive force Hc (r): 1.8 Oe Coercive force Hc (h): 1.6 Oe By setting the core width of the magnetic recording magnetic head to 7 μm,
Magnetic recording track width 7μm, track pitch 8μ
m. The width of the optical recording track 7 is the same as in the first embodiment.
It was set to 1.1 μm. Digital recording / reproducing was performed on this composite recording medium by the same recording / reproducing system as in Example 1, and the same effect as in Example 1 was obtained. For magnetic recording,
High output was obtained up to the low density region, and durability was also good.

[0043]

In the composite recording medium of the present invention, the unevenness due to the tracking groove or the reflective uneven pits is
By providing a non-magnetic intermediate layer for flattening, it is possible to prevent the unevenness and thickness of the magnetic recording layer surface from being reflected, so that excellent running stability and low noise are possible, and uniform A suitable optimum magnetic layer thickness can be secured and good recording / reproducing output can be obtained. Further, since the track pitches of the optical recording tracks can be independently selected, it is possible to select the optimum track widths for the optical recording and the magnetic recording.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an example of a composite recording medium of the present invention.

FIG. 2 is a sectional view of an essential part showing an example of a composite recording medium of the present invention.

FIG. 3 is a layout diagram showing an example of a servo tracking system using the composite recording medium of the present invention.

FIG. 4 is a sectional view of an essential part of a recording / reproducing apparatus using the composite recording medium of the present invention.

FIG. 5 is a graph showing the principle of a recording method using the composite recording medium of the present invention.

[Explanation of symbols]

100, 1: Composite recording medium 36, 2: Magnetic recording part 103, 3: Nonmagnetic intermediate layer 104, 4: Optical recording part 105, 5: Transparent substrate 106, 6: Magnetic recording track 107, 7: Optical recording track 108 , 8: Tracking grooves 109, 9: Guard band 10: Magnetic head slider 14: Optical pickup 15: Laser light 16: Optical pickup moving mechanism 17: Magnetic head slider moving mechanism 18: Tracking error detection system 19: Tracking for optical pickup Servo 20: Tracking servo for magnetic head slider 21: Coarse tracking drive unit 22: Interlocking arm 23: Coarse positioning carriage 24: Spindle motor 25: Chucking plate 33: Magneto-optical recording magnetic head 34: Magnetic Recording for a magnetic head

Claims (1)

[Claims] 1. A pit row for tracking or a groove for tracking is formed on one surface of a transparent substrate, and an optical recording portion is formed thereon, and a non-magnetic intermediate layer is provided on the optical recording portion. There is a magnetic recording portion, and the non-magnetic intermediate layer is flattened so that the thickness thereof is thicker than the depth of the pit row or the groove and the unevenness of the pit row or the groove does not appear on the surface of the non-magnetic intermediate layer. A composite recording medium that is formed.