JPH0775042B2 - Magneto-optical recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magneto-optical recording / reproducing apparatus for magneto-optically recording and magnetically reproducing information.

[Conventional technology]

As shown in FIG. 6, a magneto-optical disk 13 as a magneto-optical recording medium basically has a magnetic film 4 formed on a transparent substrate 3, and when recording is performed by magnetic field modulation, The laser light 1 having a constant intensity is condensed in a spot shape by the objective lens 2 and irradiated onto the magnetic film 4 from the substrate side 3.
Then, the temperature of the irradiation region is raised to near the Curie temperature to reduce the coercive force of the magnetic film 4, and in this state, a magnetic field that is inverted according to the recorded information is applied from the magnetic head 5 to the irradiation region. Information is recorded by reversing the magnetization (indicated by an arrow) of the magnetic film 4. On the other hand, when reproducing information, a laser beam 1 having a constant intensity, which is weaker than that at the time of recording, is focused in a spot shape by the objective lens 2 in the same manner as described above, and is irradiated onto the magnetic film 4 from the substrate side 3. Then, the information is reproduced by detecting the rotation of the plane of polarization of the reflected light.

In the magneto-optical recording by the magnetic field modulation, when the recording frequency is increased, the magnetic domain shape on the magneto-optical disk 13 is as described in the 13th Annual Meeting of the Applied Magnetic Society of Japan (1989) page 198. It is known to have a crescent shape. That is, as shown in FIG. 7, a magneto-optical disk
When the track 16 on the 13 is moving leftward (in the direction of the arrow in the figure) with respect to the light beam spot 14, the temperature rising region in the light beam spot 14 is cooled from the left side, and the coercive force is accordingly increased. Grows bigger. Then, when the temperature decreases until the coercive force becomes larger than the applied magnetic field of the magnetic head 5 (FIG. 6), the magnetization is not aligned in the direction of the applied magnetic field, and the immediately preceding information is stored. Therefore, the shape of the magnetic domains 15 ... Reflects the shape on the left side of the light beam spot 14,
As shown in the figure, it has a crescent shape convex to the left.

The size of this crescent-shaped magnetic domain 15 is
It is smaller than the above, and becomes smaller by increasing the recording frequency. Therefore, if the recording frequency is increased,
The recording density can be increased.

[Problems to be Solved by the Invention]

However, in the above-described conventional configuration, when the recording frequency is increased and high-density recording is performed, a plurality of magnetic domains 15 exist in the light beam spot 14, which causes the rotation of the polarization plane in the reflected light. There is a problem that it becomes difficult to detect and reproduce the information.

[Means for Solving the Problems]

A magneto-optical recording / reproducing apparatus according to the present invention, in order to solve the above problems, a guide groove and a land are provided on a transparent substrate,
A magneto-optical recording medium having a magnetic film formed so that the magnetic film on the guide groove and the magnetic film on the land are substantially separated from each other,
A means for converging and irradiating light such as laser light having a substantially constant intensity from the substrate side of the magneto-optical recording medium, a recording function for applying a magnetic field reversing according to recording information to the magnetic film, and a magnetic film It has a playback function to detect the change in the magnetic flux emitted,
A magnetic head provided opposite to the magnetic film of the magneto-optical recording medium is provided, and the gap length of the magnetic head is set to be substantially uniform and to be substantially equal to the recording bit length. The track width of the magnetic head is wider than the land width, and is set to be equal to or smaller than the track pitch.

[Work]

According to the above configuration, it is possible to magnetically reproduce the information recorded in high density as a crescent-shaped magnetic domain, and it is necessary to position the recording and reproducing heads which require particularly high accuracy during high density recording / reproducing. In comparison with a case where the recording magnetic head and the reproducing magnetic head are separately provided, a high reproducing output can be easily obtained.

〔Example〕

An example of the magneto-optical recording / reproducing apparatus of the present invention is a magneto-optical disk apparatus, which will be described below with reference to FIGS. 1 to 5. The members having the same functions as the members shown in the drawings of the conventional example are designated by the same reference numerals.

As shown in FIG. 1, the magneto-optical disk apparatus of this embodiment has an objective lens 2 for condensing a laser beam 1, a magneto-optical disk 13 as a magneto-optical recording medium, and a recording / reproducing magnetic head 6. It is mainly composed of and. Objective lens 2
Is arranged on the side of the transparent substrate 3 of the magneto-optical disk 13, and the magnetic head 6 faces the magneto-optical disk 13.
Is arranged on the magnetic film 4 side. The magnetic head 6 has a structure in which a coil 8 is wound around a ring-shaped magnetic core 7 having a gap 9, and the gap 9 is arranged close to the magnetic film 4 of the magneto-optical disk 13.

The magneto-optical disk 13 is basically composed of a transparent substrate 3 and a magnetic film 4 formed on the substrate 3. More specifically, as shown in FIG. A spiral guide groove 10 is provided on one side of the guide groove 10.
The magnetic film 4 is formed on the top and the land 11 corresponding to the bank portion between the guide grooves 10.

When viewed from the magnetic film 4 side, the gap 9 of the magnetic head 6 (FIG. 1) has a substantially crescent shape according to the magnetic domain shape at the time of high-density magnetic field modulation recording, as shown in FIG. The gap length is substantially uniform and is set so as to substantially match the magnetic domain length (recording bit length). Further, the track width (width above and below the magnetic core 7 in the figure) is wider than the width of the land 11 of the magneto-optical disk 13 (FIG. 2),
It is set to be approximately the same as or narrower than the track pitch (the pitch of the guide groove 10). Specifically, for example, the gap length is set to 0.1 to 0.3 μm according to the magnetic domain length, and the track width is 1 to 1.5 μm for the width of the land 11.
If m, it is set to 1 to 2 μm.

In the above configuration, the laser light 1 (FIG. 1) having a constant intensity is condensed by the objective lens 2 when recording information. Then, from the transparent substrate 3 side of the rotating magneto-optical disk 13, the magnetic film 4 on the land 11 (FIG. 2) is irradiated as a light beam spot 14. As a result, the irradiation area of the magnetic film 4 is heated, and the coercive force of this area is reduced. In this state, a high-frequency magnetic field is applied to the irradiation area of the light beam spot 14 from the magnetic head 6 by supplying the coil 8 with a drive current which is inverted at a high frequency according to the information, and is applied to the magnetic film 4 on the land 11. Information is recorded in high density as crescent-shaped magnetic domains.

On the other hand, when reproducing the information, the irradiation of the laser beam 1 is stopped,
The magnetic flux from the magnetic domain on the magnetic film 4 facing the gap 9 of the magnetic head 6 is guided to the center of the coil 8 through the magnetic core 7. Then, the coil 8 is changed by the time change of the magnetic flux.
An electromotive force that inverts according to the recorded information is generated at both ends of the magnetic field, thereby reproducing the information recorded in high density as a crescent-shaped magnetic domain.

As described above, in the magneto-optical disk apparatus of this embodiment, since the reproduction is performed by the magnetic head 6 instead of light, information recorded at high density as a crescent-shaped magnetic domain smaller than the light beam spot 14 is recorded. Since the same magnetic head 6 can be used for recording and reproducing,
It is not necessary to position the recording and reproducing heads, which require particularly high precision when performing high-density recording / reproducing, and is easier than in the case where the recording magnetic head and the reproducing magnetic head are separately provided. You can get a large playback output. Further, by making them the same, the number of parts is reduced and the structure of the device is simplified.

Furthermore, since the recording / reproducing of the high density information is performed only on the magnetic film 4 on the land 11 (FIG. 2) of the magneto-optical disk 13, the high-density information is recorded on the magnetic film 4 on the guide groove 10. The gap 9 of the magnetic head 6 can be made closer to the magnetic film 4 as compared with the case of recording / reproducing at high density. As a result, a high reproduction output can be obtained during reproduction, and the drive current supplied to the coil 8 during recording can be reduced.
It is possible to reduce the size and weight of the magnetic head 6 and reduce the power consumption.

Further, in this embodiment, the shape of the gap 9 of the magnetic head 6 (FIG. 3) is made into a substantially crescent shape in accordance with the shape of the magnetic domain at the time of high density magnetic field modulation recording. The deterioration of the signal quality and the reduction of the reproduction output due to the crosstalk and the azimuth loss from the adjacent magnetic domains hardly occur, so that the signal quality is remarkably improved and the high reproduction output can be obtained.

The crescent shape of the gap 9 is a shape in which two arcs or two substantially arc-shaped curves are translated by the gap length, but the shape is not limited to this, and as shown in FIGS. 4 and 5, It may be a crescent shape obtained by combining a plurality of straight lines. The combination of straight lines makes the gap 9 much easier to shape than the curved ones.

In the above high-density magneto-optical recording / reproducing, the magnetic film 4 contains a rare earth element commonly used in magneto-optical recording / reproducing.
It is preferable to use a ferromagnetic material having a large residual magnetization rather than a ferrimagnetic material such as a transition metal amorphous alloy because the reproduction output is large. Specifically, for example, Co
/ Pt multilayer film, CoCr alloy film, NdFe alloy film, MnBi alloy film, etc. are used. Moreover, not only such a perpendicular magnetization film but also Cr
Of course, it does not matter if an in-plane magnetized film such as O ₂ is used.
The Curie temperature is in the temperature range of 200 to 300 ° C., which is convenient for actual magneto-optical recording.

Further, in this embodiment, the laser light 1 having a wavelength of 780 nm and the NA
The objective lens 2 with (aperture ratio) of 0.5 was used,
A laser beam 1 of nm and an objective lens 2 having an NA of 0.6 may be used. The substrate 3 of the magneto-optical disk 13 is made of glass or synthetic resin such as polycarbonate or acrylic and has a thickness of about 1 to 2 mm.

In the above embodiments, the ring type is used as the magnetic head 6, but the main magnetic pole type may be used. In this case, the main magnetic pole and the auxiliary magnetic pole are integrated with a U-shaped (U-shaped) magnetic core, and a coil is wound around the magnetic core to use the main magnetic pole for recording / reproducing or reproducing the main magnetic pole. The auxiliary magnetic pole may be used for recording. In this way, by making the recording and reproducing magnetic poles the same or by integrating them, the same effect as the ring-type recording / reproducing magnetic head 6 can be obtained.

In the case of the main magnetic pole type, the ring-shaped magnetic head 6 is formed by forming the magnetic core tip portion of the main magnetic pole into a substantially crescent shape.
The same effect as when the gap 9 is formed into a crescent shape is obtained.

Further, in the above embodiment, the information was recorded at high density only on the magnetic film 4 on the land 11, but the information was recorded on the unused magnetic film 4 on the guide groove 10 at a recording density capable of optical reproduction. May be recorded, and during reproduction, normal optical reproduction may be performed by detecting rotation of the plane of polarization of reflected light. As a result, the magnetic film 4 on the magneto-optical disk 13 is effectively utilized over the entire surface.

In the above embodiments, the magneto-optical disk device has been described, but the invention can be applied to a magneto-optical card device, a magneto-optical tape device, and the like.

〔The invention's effect〕

As described above, the magneto-optical recording / reproducing apparatus according to the present invention is provided with the guide groove and the land on the transparent substrate so that the magnetic film on the guide groove and the magnetic film on the land are substantially separated from each other. A magneto-optical recording medium on which a magnetic film is formed, a means for converging and irradiating light such as laser light having a substantially constant intensity from the substrate side of the magneto-optical recording medium, and a magnetic field for reversing according to recording information A magnetic head having a recording function to be applied to the film and a reproducing function to detect a change in magnetic flux emitted from the magnetic film, and provided with a magnetic head provided facing the magnetic film of the magneto-optical recording medium, The gap length of the magnetic head is set to be substantially uniform and to be substantially equal to the recording bit length. The track width of the magnetic head is wider than the land width and is the same as or equal to the track pitch. Narrower than A configuration that is.

According to the above configuration, it is possible to magnetically reproduce information that is recorded in high density as a crescent-shaped magnetic domain, and it is necessary to position the recording and reproducing heads that require particularly high precision during high density recording / reproducing. In comparison with the case where the recording magnetic head and the reproducing magnetic head are separately provided, a high reproducing output can be easily obtained. Further, there is an effect that the number of parts is reduced and the structure of the device is simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 5 show an embodiment of the present invention. FIG. 1 is a schematic configuration diagram around a magnetic head of a magneto-optical disk device. FIG. 2 is a sectional view showing a schematic structure of a magneto-optical disk. FIG. 3 is a plan view showing a gap shape of the magnetic head. FIG. 4 is a plan view showing a gap shape of another magnetic head. FIG. 5 is a plan view showing a gap shape of another magnetic head. 6 and 7 show a conventional example. FIG. 6 is a schematic configuration diagram around the magnetic head of the magneto-optical disk device. FIG. 7 is an explanatory diagram showing the shape of magnetic domains when high density recording is performed on a magneto-optical disk. 1 is a laser beam, 3 is a substrate, 4 is a magnetic film, 6 is a magnetic head, 7 is a magnetic core, 8 is a coil, 9 is a gap, 10 is a guide groove, 11 is a land, 13 is a magneto-optical disk (magneto-optical recording). Medium), 14 is a light beam spot, and 15 is a magnetic domain.

Continued front page (72) Inventor Tatsushi Yamamoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation (72) Toshio Ishikawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Prefecture Sharp Corporation (56) References JP-A-54-21709 (JP, A) JP-A-63-217548 (JP, A) JP-A-51-107810 (JP, A)

Claims (1)

[Claims] 1. A guide groove and a land are provided on a transparent substrate,
A magneto-optical recording medium in which a magnetic film is formed so that the magnetic film on the guide groove and the magnetic film on the land are substantially separated from each other, and light such as laser light having a substantially constant intensity from the substrate side of the magneto-optical recording medium. Has a means for condensing and irradiating the magnetic field, a recording function for applying a magnetic field reversing according to recording information to the magnetic film, and a reproducing function for detecting a change in magnetic flux emitted from the magnetic film. A magnetic head provided so as to face the magnetic film of the recording medium, and the gap length of the magnetic head is substantially uniform, and
The optical head is set so as to substantially match the recording bit length, and the track width of the magnetic head is set to be wider than the land width and to be equal to or narrower than the track pitch. Magnetic recording / reproducing device.