JP3022375B2 - Magneto-optical recording medium recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording / reproducing apparatus for recording and reproducing information on / from a magneto-optical recording medium such as a magneto-optical disk.

[0002]

2. Description of the Related Art FIG. 5 shows a magneto-optical disk system as a conventional example of the present invention using a magneto-optical disk as a magneto-optical recording medium. In this conventional example, when a disk-shaped single-sided magneto-optical recording medium 50 is mounted, an optical system including a laser device 58 and an objective lens 59 is located on the upper surface side of the single-sided magneto-optical recording medium 50, and A magnetic field generator 60 is configured to be located on the lower surface side of the single-sided magneto-optical recording medium 50.

[0003] The numerical aperture (hereinafter referred to as "NA") of the objective lens 59 is set to 0.50 to 0.53. A drive system (not shown) is provided to drive the optical system in the focusing direction and the tracking direction with respect to the magneto-optical recording medium 50. The magnetic system is also provided with another drive system (not shown) for driving in the arrow direction and the tracking direction in FIG.

In this magneto-optical disk system, a magnetic field modulation method is employed for recording information. In this magnetic field modulation method, a sufficient excitation current cannot be obtained because the magnetic field needs to be inverted and controlled at high speed, and the intensity of the generated magnetic field is limited. It is provided near a recording magnetic layer 53 described later. In the magnetic field modulation method, overwriting (overwriting) can be performed.

[0005] The single-sided magneto-optical recording medium 50 is, for example, formed on one surface of a translucent transparent substrate 51 such as polycarbonate.
A dielectric layer 52, a recording magnetic layer 53 having a large magneto-optical effect such as a rare earth-transition metal alloy amorphous thin film, a dielectric layer 54, a reflective layer 55, and a protective cover 56 are sequentially laminated. The thickness t ₁ of the transparent substrate 51 is constant, and was conventionally set to 1.2 mm.

Next, the operation will be briefly described. First, a single-sided magneto-optical recording medium 50 is mounted on a rotating disk (not shown) and driven to rotate, and a magnetic field from a magnetic field generator 60 is applied to the recording magnetic layer 53. This magnetic field is subjected to high-speed reversal control, and the recording magnetic layer 53 to which the magnetic field is applied
By focusing the laser beam emitted from the laser device 58 through the objective lens 59, the recording magnetic layer 53 in the region where the laser beam is focused can be magnetized, and the information signal is overwritten in real time. be able to.

[0007]

By the way, in order to make the above-mentioned optical system, magnetic system and the recording / reproducing head having these driving systems simple and compact, the optical system and the magnetic system are integrated. It is conceivable to arrange them on the same side of the single-sided magneto-optical recording medium 50. That is, a configuration is conceivable in which the magnetic field generator 60 is arranged on the objective lens 59 side (the transparent base 51 side) and these are integrated. However, in this configuration,
The distance from the magnetic field generator 60 to the recording magnetic layer 53 becomes longer due to the 1.2 mm thick transparent substrate 51, and it becomes impossible to apply a sufficiently strong magnetic field to the recording magnetic layer 53.

On the other hand, with the increase in the amount of information in recent years, a double-sided magneto-optical recording medium having the above-described recording magnetic layer and the like on both sides of a single magneto-optical recording medium and capable of recording information on both sides has been developed. Is being developed. However, in order to record and reproduce information on and from such a double-sided magneto-optical recording medium, for example, a recording / reproducing head having an optical system and a magnetic system shown in FIG. It is extremely difficult to apply a strong magnetic field.

In a magnetic field generator of a magnetic field modulation system, a high-frequency current corresponding to a high-frequency data signal needs to flow through an electromagnetic coil. However, the higher the frequency, the more difficult it is for the current to flow through the coil. In addition to the limitation on the strength of the recording medium, the distance from the magnetic field generator to the recording magnetic layer is considerably long because of the thick transparent substrate. Therefore, in the conventional magneto-optical disk system, it is extremely difficult to perform double-sided magneto-optical recording by the magnetic field modulation method.

Therefore, according to the present invention, even if the recording / reproducing head is simple and compact, and the magnetic field generating means is of a magnetic field modulation type and the intensity of the generated magnetic field is limited, the information recording layer is formed on both sides. It is an object of the present invention to provide a magneto-optical recording medium recording / reproducing apparatus capable of recording and reproducing information with respect to a magneto-optical recording medium included in the present invention.

[0011]

According to the present invention, a recording / reproducing apparatus for a magneto-optical recording medium has a numerical aperture on a recording layer of a magneto-optical recording medium having a light transmitting layer having a thickness of 0.1 to 0.6 mm.
A magneto-optical recording / reproducing apparatus for recording and reproducing information by converging a laser beam emitted from a light source through an objective lens of 0.70 to 0.55 and the light transmitting layer, between the objective lens and the magneto-optical recording medium, the objective les in contact with the objective lens
Light-transmitting plate that extends perpendicular to the optical axis of the lens
And the coil plate is placed on the surface of the plate that extends perpendicular to the optical axis.
It is characterized in that the turns are formed to constitute the magnetic field generating means.

In the magneto-optical recording / reproducing apparatus according to the present invention, the objective lens is provided between the objective lens for converging the laser beam emitted from the light source and the magneto-optical recording medium.
A plate material is provided in contact with the
Since emission is formed the magnetic field generating means is constituted, is integral with the objective lens and the magnetic field generating means, Ya objective lens
The drive system can be shared by magnetic field generating means, etc.
Since the coil pattern can be easily formed, the structure including the objective lens and the magnetic field generating means is simple and small. What
The plate material on which the coil pattern is formed is the objective lens
And the magneto-optical recording medium, but the plate material is
It is transparent and the coil pattern is compatible with the objective lens.
Because it is not formed directly,
There is no problem in the irradiation of the laser beam to.

Further, since the magnetic field generating means is disposed between the objective lens and the magneto-optical recording medium, the objective lens, the magnetic field generating means and the like can be disposed on both sides of the magneto-optical recording medium. Since the thickness of the light transmitting layer of the magneto-optical recording medium is as thin as 0.1 to 0.6 mm, the distance from the magnetic field generating means to the recording layer can be reduced even if the light transmitting layer is interposed. Moreover, the numerical aperture of the objective lens is 0.70
Since it is as large as 0.55, it can be
Can also reduce the distance from the magnetic field generation means to the recording layer
it can. Furthermore, the plate material extends perpendicular to the optical axis of the objective lens.
The coil pattern is formed on this vertically extending surface.
The magnetic field generating means is configured to cover a large area.
To form a coil pattern and generate a magnetic field.
The intensity of the magnetic field generated from the means can be increased. this
For et al., It is possible to apply a predetermined magnetic field to the recording layer of the double-sided magneto-optical recording medium. Also, the numerical aperture of the objective lens
Is as large as 0.70 to 0.55, so the focused laser
The minimum diameter of the beam is small. However, magneto-optical recording media
0.1-0.6mm thickness of light transmission layer and objective lens
The numerical aperture of 0.70 to 0.55 corresponds to
Therefore, even if the numerical aperture of the objective lens is large,
Ma aberration is suppressed. Further, the optical transparency of the magneto-optical recording medium is
Since the thickness of the overlayer is 0.1 mm even if it is thin,
The diameter of the laser beam applied to the recording medium is too small
Laser beam irradiation on the magneto-optical recording medium
Not inhibited by dust.

The minimum diameter (2ω ₀ ) of the laser beam focused by the objective lens is expressed by the following equation. 2ω ₀ = 0.82 × λ / NA (λ: wavelength of laser beam)

Therefore, if the NA of the objective lens is large,
As is clear from the above equation, the minimum diameter of the focused laser beam is reduced, the recording density is increased, and reproduction corresponding to the recording density can be performed.

Further, if the NA of the objective lens is large, the thickness is also large, but if the thickness of the light transmitting layer of the magneto-optical recording medium is small, the thickened objective lens comes into contact with the magneto-optical recording medium. Never.

When the NA of the objective lens and the thickness t of the light transmitting layer of the magneto-optical recording medium change, the aberration value of the objective lens changes as follows. (A) Spherical aberration W ₄₀ (Sin α = NA) (N: refractive index of light transmitting layer of magneto-optical recording medium)

(B) Coma aberration W ₃₁ (Θ: skew)

Since the spherical aberration W ₄₀ can be corrected by the objective lens, there is basically no problem. However, if the thickness t of the light transmitting layer varies, a problem arises. Therefore, it is desirable to suppress the thickness t to within a tolerance. On the other hand, since the coma aberration W ₃₁ can not be corrected in the objective lens, the absolute value thereof is preferably as small. Then, even if the NA of the objective lens is large, if the thickness t of the light transmitting layer is small,
The absolute value of the coma aberration W ₃₁ is not increased. Therefore, even if the NA of the objective lens is large, the aberration hardly causes a problem, and recording and reproduction can be performed at a high density.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to third embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view showing a first embodiment in which the present invention is applied to a magneto-optical disk system, and shows a basic configuration of the magneto-optical disk system. As shown in FIG. 1, this magneto-optical disk system is composed of an objective lens 2 having an NA of 0.55 to 0.70, and an optical glass 8 on which a coil pattern 7 is formed and which has optical transparency. Magnetic field generating device 9.

The disk-shaped single-sided magneto-optical recording medium 40 is
The thickness t ₂ is the 0.1~0.6mm thin light-transmitting substrate 41
In addition, a dielectric layer 42, a recording magnetic layer 43, a dielectric layer 44, a reflective film 45, and a protective cover 46 are sequentially laminated. The single-sided magneto-optical recording medium 40 is irradiated with a laser beam from a laser beam device (not shown) so that recording and reproduction can be performed.

The magnetic field generator 9 is of a magnetic field modulation type, which will be described later in detail with reference to FIG. Dielectric layer 42
Since the thickness of much thinner than the thickness t ₂ of the light-transparent substrate 41, the dielectric layer to the thickness t ₂ of the light-transparent substrate 41 4
2 need not be considered. The objective lens 2 which is an optical system and the optical glass 8 which is a magnetic system are adhered so as to be integral with each other, and the coil pattern 7 is arranged close to the magneto-optical recording medium 40.

As described above, since the thickness t ₂ of the light-transmitting substrate 41 is much smaller than the conventional one and the coil pattern 7 is close to the light-transmitting substrate 41, the coil pattern 7 and the recording magnetic layer 43 Is preferably short. Further, since the optical system and the magnetic system are integrated, the size of the magneto-optical pickup as a recording / reproducing head including these can be reduced, the price can be reduced, and the second and the later-described optical heads can be used. As described in the third embodiment, recording and reproduction on a double-sided magneto-optical recording medium can be performed.

As the magneto-optical recording medium used in the magneto-optical disk system, it is preferable to use, for example, a 3.5-inch magneto-optical disk in a fixed manner or in a cartridge holder.

The NA of the objective lens 2 is 0.55 to 0.70
Therefore, the depth of focus (= λ / NA ² , λ: wavelength of the laser beam) is shallow. However, the magneto-optical disk is small as described above, and an actuator (not shown) constituting a drive system for the magneto-optical pickup is miniaturized, and its frequency characteristics are improved. Since the objective lens 2 sufficiently follows, there is no problem that the depth of focus of the objective lens 2 is shallow.

The spherical aberration W ₄₀ is corrected in the objective lens 2. Coma aberration W ₃₁ is also, as in the above-mentioned objective lens 2
The NA is no problem since the thickness t ₂ of the light-transmitting substrate 41 is thin be larger. Table 1 below, coma W ₃₁ is equivalent to the coma aberration W ₃₁ in the case of the thickness t = 1.2 mm of NA = 0.50 and the light-transparent substrate of a conventional such objective lens (light transmission layer) NA and thickness t are shown for four cases.

[0027]

[Table 1]

As shown in Table 1 above, even when the NA is 0.55 to 0.70, the thickness t of the light-transmitting substrate (light-transmitting layer) is reduced to 0.6 to 0.1 mm. For example, it can be seen that the coma can be made equal to or less than the conventional value, and there is no problem. Further, since the NA of the objective lens 2 is large, the objective lens 2 is thick.
₂ is thin, the distance d (working distance) between the objective lens 2 and the magneto-optical recording medium 40 is equal to or greater than a predetermined value, as shown in FIG. Do not touch.

Further, since the cartridge holder type or the fixed type is adopted in the magneto-optical recording medium, dust which is a problem in the magneto-optical disk system does not cause any problem in this case. Although the particle size and distribution of the above-mentioned dust are problematic, the laser beam is
The radius r (see FIG. 1) of the circle projected on 1 is r = t · tan (arc sin (NA / N)). As can be seen from this equation, the radius r decreases as the thickness t of the light transmitting layer decreases, but since the radius r does not decrease significantly due to the large NA, the first
In the embodiment, there is no particular problem of the dust described above.

As described above, in the magneto-optical disk system of the first embodiment, the NA of the objective lens 2 is set to 0.5
Light-transmitting substrate (light-transmitting layer) 41 with a value of 5 to 0.70
It is of a thickness t ₂ to 0.6~0.1mm. For this reason, as compared with a conventional system using an objective lens having an NA of 0.50, as can be seen from the equation, the recording density is (0.55 / 0.50) ² to (0.70 / 0.50). ²
≒ 1.2 to 2 times, and it can be seen that the various problems caused by increasing the NA can be all solved. Therefore, it is possible to increase the capacity of the magneto-optical disk system without any problem.

Next, a more detailed configuration of the magneto-optical disk system of the first embodiment will be described as second and third embodiments. FIG. 2 is a sectional view of a second embodiment of the magneto-optical disk system according to the present invention.

In the second embodiment, first and second magneto-optical pickup devices as recording / reproducing heads each having an optical system and a magnetic system are provided with a first double-sided magneto-optical device as shown in FIG. They are arranged to face each other with the recording medium 10 interposed therebetween. The first magneto-optical pickup device arranged on the upper surface side of the double-sided magneto-optical recording medium 10 and the second magneto-optical pickup device arranged on the lower surface side have the same configuration as described below. Their components 1-9 and 1
'To 9' correspond.

The first and second magneto-optical pickup devices are constituted by pickups 6 and 6 'which are optical systems and the above-described magnetic field generators 9 and 9' which are magnetic systems. Further, the pickups 6 and 6 ′ include the laser devices 1 and 1 ′,
As described above, the objective lenses 2 and 2 ′ having NA of 0.55 to 0.70, the coil bobbins 4 and 4 ′ around which the focus coils 3a and 3a ′ and the tracking coils 3b and 3b ′ are wound, and And magnets 5, 5 'arranged around the coil bobbins 4, 4'.

The coil bobbins 4 and 4 'are, for example, cylindrical, and the focus coils 3a and 3a' for driving the pickups 6 and 6 'in the direction F in FIG. 2 and the pickups 6 and 6' in FIG. The wound tracking coils 3b, 3b 'for driving in the T direction are provided around the coil bobbins 4, 4'. Coil bobbin 4,
Lens support members 2a, 2a 'are provided at positions near the ends 4a, 4a' of the 4 ', and objective lenses 2, 2' for converging the laser beams emitted from the laser devices 1, 1 '. Are supported by the lens support members 2a and 2a '.

As shown in FIG. 3, the magnetic field generators 9 and 9 'apply a current of a high-frequency signal to the surfaces 8a and 8a' of optical glasses 8 and 8 'having optical transparency such as quartz. The conductors 7a, 7a 'for flowing and generating a magnetic field are formed as spiral coil patterns 7, 7'.

On the back surfaces 8b, 8b 'of the optical glasses 8, 8' on which the coil patterns 7, 7 'are not formed, the centers of the coil patterns 7, 7' and the centers of the objective lenses 2, 2 'coincide. The coil bobbins 4, 4
The end portions 4a and 4a 'of the' are fixed by bonding. Therefore, the laser beam can be focused on the center of the generated magnetic field, and it is not necessary to adjust the center when assembling the pickup.

The use of quartz as the optical glasses 8 and 8 'is merely an example, and any material may be used as long as it is light-transmissive. Print coils and thin-film coils are used as the coil patterns 7 and 7'. Can be used. Further, in order to prevent reflection of the laser beam, holes through which the laser beam passes may be provided in the optical glasses 8 and 8 '.

On the other hand, the double-sided magneto-optical recording medium 10 shown in FIG.
Has been proposed by the present applicant in the specification and the drawings of Japanese Patent Application No. 1-142563, and the common substrate 1
The recording section 16, the photocurable resin layer 17, and the transparent protective plate 18 are provided on both surfaces of the recording medium 1, respectively. Transparent protective plate 1
8 and the photocurable resin layer 17 both have translucency, and the sum of their thicknesses can be 0.6 mm or less.

In each recording section 16, the reflection layer 15
Are laminated so as to be disposed closer to the base 11 than the recording magnetic layer 12, and the reflection layer 15, the second dielectric layer 14, the recording magnetic layer 12, and the first dielectric layer 13 are respectively disposed from the base 11 side. Are stacked in this order. In this double-sided magneto-optical recording medium 10, since the substrate 11 is common, the thickness can be suppressed to approximately half as compared with the conventional double-sided magneto-optical recording medium by laminating the substrates.

Next, the operation will be described. In the first magneto-optical pickup device, when the focus driving current is supplied to the focus coil 3a, the coil bobbin 4 and the magnetic field generator 9 provided on the coil bobbin 4 are indicated by an arrow F in FIG. Objective lens 2
Is driven and displaced in the focus direction which is the direction of the optical axis. Further, when a tracking drive current is supplied to the tracking coil 3b, the coil bobbin 4 and the magnetic field generator 9 are moved by the objective lens 2 indicated by an arrow T in FIG.
Is driven and displaced in a tracking direction, which is a direction orthogonal to the optical axis of the optical disk.

In the second magneto-optical pickup device, the coil bobbin 4 'and the magnetic field generating device 9' are connected in the same manner as in the first magneto-optical pickup device and in synchronization with the driving displacement of the first magneto-optical pickup device. Are driven and displaced in the F and T directions.

At the same time as the above-described driving displacement in the first and second magneto-optical pickup devices, a high-frequency current signal obtained by amplifying a signal to be recorded is applied to the coil patterns 7, 7 '.
To generate a magnetic field. This magnetic field is subjected to high-speed inversion control according to a recording signal, and is applied to the recording magnetic layers 12 and 12. Then, the recording magnetic layer 1
The laser beam emitted from the laser device 1, 1 'is applied to the objective lens 2,
The information is recorded by focusing the laser beam through the 2 ′ and the optical glasses 8 and 8 ′, and raising the temperature of the region where the laser beam is focused in the recording magnetic layers 12 and 12 to the Curie point or higher.

As is clear from the above description, in the magneto-optical disk system according to the second embodiment, the optical system as the pickups 6, 6 'including the laser devices 1, 1' and the objective lenses 2, 2 ', etc. A magnetic field generator 9 comprising coil patterns 7, 7 'formed on optical glasses 8, 8',
Since the magnetic system 9 ′ is provided on the same side of the double-sided magneto-optical recording medium 10, the distance between the coil patterns 7, 7 ′ and the double-sided magneto-optical recording medium 10 is short.

Further, the transparent protective plate 18 and the photocurable resin layer 17
In the end, the distance between the coil patterns 7, 7 'and the recording magnetic layers 12, 12 is extremely short, and the double-sided light by the magneto-optical modulation method, which has been considered extremely difficult until now, is used. Recording and reproduction on a magnetic recording medium are possible.

Further, since the coil bobbins 4, 4 'and the magnetic field generators 9, 9' are bonded and fixed, the center of the objective lens 2, 2 'and the center of the magnetic field from the magnetic field generators 9, 9' are aligned. Easy alignment. Since the pickups 6 and 6 'and the magnetic field generators 9 and 9' are linked by the focus servo, the double-sided magneto-optical recording medium 10
Can always be constant in intensity.
Further, a drive system for a magnetic system, which has been conventionally required, is omitted. Further, since there is a sufficient space for disposing the magneto-optical pickup device, the degree of freedom in design is increased.

In the second embodiment, recording and reproduction can be performed on the double-sided magneto-optical recording medium 10 by various methods. For example, simultaneous use of the laser devices 1, 1 'and the magnetic field generators 9, 9' enables simultaneous recording on the upper surface and the lower surface of the double-sided magneto-optical recording medium 10. 'Can be used for simultaneous reproduction. As a result, a larger capacity can be achieved and information can be recorded and reproduced at a higher speed.

Further, after recording or reproduction is first performed on one side of the double-sided magneto-optical recording medium 10, recording or reproduction can be performed on the other side.
Recording and reproduction can be performed twice as large as a single-sided magneto-optical recording medium. In this case, both magnetic field generators 9 and 9 'can be used simultaneously for recording on one surface. Therefore, a magnetic field can be applied to the recording magnetic layer 12 from both sides, and recording can be performed with a larger magnetic field. Further, when recording on one surface, it is possible to perform recording using only the magnetic field generator arranged on the other surface side.

Next, a third embodiment will be described. As shown in FIG. 4, this third embodiment uses the same magneto-optical disk system as that of the second embodiment shown in FIG. 2 and uses the second double-sided magneto-optical recording medium 30 shown in FIG. It is configured so that recording and reproduction can be performed.

The double-sided magneto-optical recording medium 30 was prepared by one of the inventors of the present application together with the other inventor in Japanese Patent Application No. 1-274734.
In the specification and the drawings, a high magnetic permeability layer 32, a photocurable resin layer 33, a magneto-optical recording layer 34, an adhesive layer 35, and a transparent protective plate 36 are provided on both surfaces of a common base 31, respectively. It is configured by being sequentially laminated. Both the transparent protective plate 36 and the adhesive layer 35 have translucency, and the sum of their thicknesses can be 0.6 mm or less.

The high magnetic permeability layer 32 is made of, for example, Fe, Co,
It is made of a material having a high magnetic permeability, such as a transition metal such as Ni, or an alloy thereof, such as permalloy, sendust, or an amorphous magnetic alloy, and can enhance the perpendicular magnetic field efficiency of the double-sided magneto-optical recording medium 30.

In the third embodiment, the double-sided magneto-optical recording medium 3
0 has the high magnetic permeability layer 32, and the magnetic flux from the magnetic field generators 9 and 9 'forms a magnetic closed loop, for example, as shown by a broken line in FIG. It is preferable because the magnetic flux applied to the medium 30 can be effectively focused and the vertical magnetic field efficiency can be increased.

Also in the third embodiment, recording or reproduction can be performed simultaneously on both sides of the double-sided magneto-optical recording medium 30, and after recording or reproduction is performed on one side, the other is performed. It is also possible to perform recording or reproduction on the surface.

As described above, in the second and third embodiments,
As in the first embodiment, since the NA of the objective lenses 2 and 2 'is larger, higher-density recording and reproduction can be performed, and a double-sided magneto-optical recording medium can be used. High-speed recording and reproduction are possible.
Accordingly, a magneto-optical disk system having a large capacity can be provided.

In the first to third embodiments, the magnetic field generators 9 and 9 'are of the magnetic field modulation type. However, the present invention can be applied to other types such as an optical modulation type. Although the first to third embodiments are magneto-optical disk systems, the present invention is, of course, not limited to this.

[0055]

In the present invention according to the magneto-optical recording medium recording and reproducing apparatus according to the present invention, since the structure containing the objective lens and the magnetic field generating means or the like is simple and compact, simple and compact recording and reproduction head, magneto-optical Since a required magnetic field can be applied to the recording layers on both sides of the recording medium, information can be recorded and reproduced on a magneto-optical recording medium having information recording layers on both sides. Also, the focused laser beam
The minimum diameter of the lens is small, but the coma of the objective lens
Laser for magneto-optical recording media
Recording because the beam irradiation is not disturbed by dust
And reproduction can be performed at high density.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a magneto-optical disk system according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a magneto-optical disk system according to a second embodiment of the present invention.

FIG. 3 is a front view of an optical glass having a coil pattern which can be used in the magneto-optical disk system shown in FIGS. 1, 2 and 4;

FIG. 4 is a sectional view showing a configuration of a magneto-optical disk system as a third embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a magneto-optical disk system as a conventional example of the present invention.

[Explanation of symbols]

2, 2 'Objective lens 9, 9' Magnetic field generator (magnetic field generating means) 10, 30, 40 Magneto-optical recording medium 16 Recording unit (recording layer) 17, 18 Photocurable resin layer and transparent protective plate (light transmitting layer) 34 Magneto-optical recording layer (recording layer) 35, 36 Adhesive layer and transparent protective plate (light transmitting layer) 41 Transparent substrate (light transmitting layer) 43 Recording magnetic layer (recording layer) t ₁ , t ₂ light transmitting layer Thickness

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 11/105

Claims (1)

(57) [Claims] 1. A recording layer of a magneto-optical recording medium having a light transmitting layer having a thickness of 0.1 to 0.6 mm has a numerical aperture of 0.7.
A magneto-optical recording / reproducing apparatus for recording and reproducing information by converging a laser beam emitted from a light source through an objective lens of 0 to 0.55 and the light transmitting layer; and between the magneto-optical recording medium, the pair
Spreads perpendicular to the optical axis of this objective lens in contact with the object lens
A light-transmitting plate is provided, and a coil pattern is formed on a surface of the plate which extends perpendicularly to the optical axis.
Magneto-optical recording medium recording and reproducing apparatus characterized by but is formed by the magnetic field generating means is constituted.