JPH0448406A - Magneto-optical recording and reproducing device and magnetic head - Google Patents

Abstract

PURPOSE:To easily obtain a high regenerative output by providing a magnetic head, which impresses a magnetic field to be inverted corresponding to information to a magnetic film in the case of recording and detects the change of magnetic flux outputted from the magnetic film at the time of reproducing, counter to the magnetic film of a magneto-optical recording medium CONSTITUTION:When reproducing information, the irradiation of a laser beam 1 is stopped, and the magnetic flux outputted from a magnetic domain on a magnetic film 4 counter a gap 9 of a magnetic head 6 is guided through a magnetic core 7 to the center of a coil 8. According to the change of this magnetic flux due to the lapse of time, electromotive force to be inverted corresponding to the recorded information is generated at the both ends of the coil 8, and by such a force, the information recorded with high density as the crescent type magnetic domain is reproduced. Thus, since the information is reproduced not by the laser beam but by the magnetic head 6, it is not necessary to set a position between heads for recording and reproducing to require high accuracy especially at the time of high-density recording and reproducing. Thus, the high regenerative output can be easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magneto-optical recording/reproducing apparatus and a magnetic head for magneto-optically recording and magnetically reproducing information.

[Prior Art] 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 a magnetic film 4 is formed on this by magnetic field modulation. When recording, a laser beam 1 of a constant intensity is focused into a spot by an objective lens 2, and is irradiated onto the magnetic film 4 from the substrate side 3. Then, the temperature of the irradiated area is raised to near the Curie temperature to lower the coercive force of the magnetic film 4, and in this state, a magnetic field that is reversed according to the recorded information is applied to the irradiated area from the magnetic helad 5. By this, the magnetization (indicated by the arrow) of the magnetic film 4 is reversed, and information is recorded. on the other hand,
When reproducing information, a laser beam 1 having a constant intensity lower than that during recording is focused into a spot 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. Information is then reproduced by detecting the rotation of the plane of polarization in the reflected light.

In magneto-optical recording using magnetic field modulation, when the recording frequency is increased, the shape of the magnetic domain on the magneto-optical disk 13 becomes It is known to be crescent-shaped. That is, as shown in FIG. 7, the track 16 on the magneto-optical disk 13
4, the temperature rising region within the light beam spot 14 cools from the left side, and the coercive force also increases accordingly. When the temperature drops until the coercive force becomes larger than the magnetic field applied by the magnetic heald 5 (FIG. 6), the magnetization is no longer aligned in the direction of the applied magnetic field, and the immediately previous information is stored. Therefore, the shape of the magnetic domain 15... is the same as the shape of the light beam spot 14.
Reflecting the shape of the left side, it has a crescent shape convex to the left, as shown in the figure.

The size of this crescent-shaped magnetic domain 15 is smaller than the light beam spot 14, and by increasing the recording frequency,
It gets even smaller. Therefore, by increasing the recording frequency, the recording density can be increased.

[Problem to be solved by the invention]

However, in the above-mentioned conventional configuration, when high-density recording is performed by increasing the recording frequency, a plurality of magnetic domains 15 exist within the light beam spot nod 14, and for this reason,
This has the problem that it is difficult to detect the rotation of the polarization plane in the reflected light and reproduce information.

[Means to solve the problem]

In order to solve the above problem, the magneto-optical recording and reproducing device according to the invention of claim 1 provides a magneto-optical recording medium in which a guide groove and a land are provided on a transparent substrate, and a magnetic film is formed thereon. In a magneto-optical recording and reproducing apparatus that records information on a magnetic film while condensing and irradiating light such as a laser beam of approximately constant intensity from the substrate side of the magneto-optical recording medium, The present invention is characterized in that a magnetic head is provided facing the magnetic film of the magneto-optical recording medium, which applies a reversing magnetic field to the magnetic film and detects changes in the magnetic flux emitted from the magnetic film during reproduction.

In order to solve the above problem, the magneto-optical recording and reproducing device according to the invention of claim 2 is the magneto-optical recording and reproducing device according to claim 1, wherein It is characterized in that information is recorded and reproduced only on the magnetic film.

In order to solve the above-mentioned problem, a magnetic head according to the invention of claim 3 has a magnetic head having a gap provided opposite to a magnetic film, in which the gap is approximately shaped in accordance with the shape of the magnetic domain of the magnetic film. It is characterized by being formed in the shape of a crescent moon.

[Function] According to the structure of claim 1, a magnetic field that is reversed according to information during recording is applied to the magnetic film, and a magnetic head that detects a change in the magnetic flux emitted from the magnetic film during reproduction is connected to the magnetic head. Since it is provided facing the magnetic film of the magneto-optical recording medium, information recorded at high density as crescent-shaped magnetic domains can be magnetically reproduced, and it is also suitable for recording and reproducing applications that require particularly high precision during high-density recording and reproduction. There is no need to position the playback heads,
Compared to the case where a recording magnetic head and a reproducing magnetic head are provided separately, a high reproduction output can be easily obtained.

According to the structure of claim 2, since information is recorded and reproduced only on the magnetic film on the land of the magneto-optical recording medium, high-density recording and reproduction is performed on the magnetic film on the guide groove. The magnetic head can be brought closer to the magnetic film than in the case where this method is used. As a result, a high reproduction output can be obtained during reproduction, and the drive current for the magnetic head can be reduced during recording.

According to the structure of claim 3, since the gap is formed in a substantially crescent shape in accordance with the shape of the magnetic domain of the magnetic film, when reproducing information recorded at high density as a crescent-shaped magnetic domain, the gap from the adjacent magnetic domain is Crosstalk and azimuth loss are less likely to occur, resulting in high signal quality and high playback output.

〔Example〕

An example of the magneto-optical recording and reproducing apparatus of the present invention is a magneto-optical disk device, which will be described below with reference to FIGS. 1 to 5. Note that members having the same functions as those shown in the drawings of the conventional example are given the same reference numerals.

As shown in FIG. 1, the magneto-optical disk device of this embodiment includes an objective lens 2 for condensing a laser beam 1, a magneto-optical disk 13 as a magneto-optical recording medium, and a magnetic head 6 for recording and reproducing. It is mainly composed of. The objective lens 2 is placed on the side of the transparent substrate 3 of the magneto-optical disk 3, and the magnetic head 6 is placed opposite to the transparent substrate 3 of the magneto-optical disk 1.
3 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 provided with a gap 9.
It is arranged close to the magnetic film 4 of No. 3.

The magneto-optical disk 13 basically consists 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, and a magnetic film 4 is formed on the guide groove 10 and on lands 11 corresponding to the banks between the guide grooves 10. has been done.

The gap 9 of the magnetic hendroid (Fig. 1) is shaped like a crescent moon when viewed from the magnetic film 4 side, as shown in Fig. 3, in accordance with the shape of the magnetic domain during high-density magnetic field modulation recording. The gap length is approximately uniform and is set to approximately match the magnetic domain length (recording bit length). In addition, the track convergence (the vertical width of the magnetic core 7 in the same figure) is
The width is set to be wider than the width of the land 11 of the magneto-optical disk 13 (FIG. 2), and about the same as the trunk pitch (the groove of the guide groove 10), or narrower than that, specifically, for example, , the gap length is 0.1~ according to the magnetic domain length.
The trunk width is set to 0.3 μm, and the trunk width is set to 0.3 μm.
If the width of 1 is 1 to 1.5 μm, it is set to 1 to 2 μm.

In the above configuration, when recording information, a laser beam 1 (FIG. 1) of a constant intensity is focused by an objective lens 2. A light beam spot 1 is then applied to the magnetic film 4 on the land 11 (FIG. 2) from the transparent substrate 3 side of the rotating magneto-optical disk 13.
As a result, the temperature of the irradiated region of the magnetic film 4 increases, and the coercive force of this portion decreases. In this state, a drive current that is reversed at a high frequency according to the information is applied to the coil 8.
By supplying a high frequency magnetic field to the irradiation area of the light beam 14 from the magnetic hexagon, information is recorded at high density in the magnetic film 4 on the land 11 in the form of crescent-shaped magnetic domains.

On the other hand, when reproducing information, the irradiation of laser light 1 is stopped,
Magnetic flux emitted 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, due to the time change of this magnetic flux, the coil 8
An electromotive force is generated at both ends of the magnetic field that inverts according to the recorded information, thereby reproducing the information recorded at high density as a crescent-shaped magnetic domain.

As described above, since the magneto-optical disk device of this embodiment is configured to perform reproduction using the magnetic head 6 instead of using light, information is recorded at high density as a crescent-shaped magnetic domain smaller than the light beam spot 14. can be played, and
Since the same magnetic head 6 is used for recording and reproducing, there is no need to perform positioning between recording and reproducing nodes, which require particularly high precision during high-density recording and reproducing. A larger reproduction output can be easily obtained compared to the case where the reproduction magnetic field and the reproduction magnetic field are provided separately. Also,
By making them the same, the number of parts is reduced and the configuration of the device is simplified.

Furthermore, since the configuration is such that high-density information is recorded and reproduced only on the magnetic film 4 on the land 11 (FIG. 2) of the magneto-optical disk 13, the magnetic film 4 on the indoor groove 10 is The gap 9 of the magnetic head 6 can be brought closer to the magnetic film 4 than when recording and 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 can be reduced during recording, so that the magnetic head 6 can be made smaller, lighter, and consume less power.

In addition, in this embodiment, the shape of the gap 9 of the magnetic head 6 (Fig. 3) is made into a crescent shape to match the shape of the magnetic domain during high-density magnetic field modulation recording, so it can be compared with a straight shape. Therefore, deterioration of signal quality and reduction in reproduction output due to crosstalk and azimuth loss from adjacent magnetic domains are less likely to occur, and signal quality is significantly improved and 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 in parallel by the gap length, but the shape is not limited to this, as shown in FIGS. 4 and 5. It may be a crescent shape obtained by combining a plurality of straight lines. A straight line combination makes it much easier to form the gap 9 than a curved line.

In the above high-density magneto-optical recording and magnetic reproduction, magnetic 1I14
, compared to ferrimagnetic materials such as rare earth-transition metal amorphous alloys commonly used in magneto-optical recording and optical reproduction.
Rather, it is preferable to use a ferromagnetic material with large residual magnetization because the reproduction output is large. Specifically, for example,
A Co/P multilayer film, a C0Cr alloy film, a NdFe alloy film, a MnB1 alloy film, etc. are used. Furthermore, instead of using such a perpendicular magnetization film, an in-plane magnetization film such as Cry may of course be used. In addition, the Curie temperature is 2
A temperature range of 00 to 300°C is convenient for actually performing magneto-optical recording.

Further, in this example, the laser beam 1 with a wavelength of 780 nm and the objective lens 2 with an NA (numerical aperture ratio) of 0.5 were used.
A laser beam 1 with a wavelength of 830 nm and an objective lens 2 with an NA of 0.6 may be used. In addition to glass, synthetic resin such as polycarbonate or acrylic is used for the magneto-optical disk 130 substrate 3, and its thickness is approximately 1 to 2 mm.

In the above embodiments, a ring type magnetic head 6 is used, but a main pole type may also be used. In this case, either the main magnetic pole and the auxiliary magnetic pole are integrated into a U-shaped magnetic core, a coil is wound around the magnetic core, and the main magnetic pole is used for recording and reproducing, or the main magnetic pole is used for reproducing. The auxiliary magnetic pole may be used for recording purposes. By making the magnetic poles for recording and reproducing the same, or by making them negative magnetized in this manner, the same effect as that of the ring-shaped recording/reproducing magnetic head 6 can be obtained.

In addition, in the case of the main pole type, by making the tip of the magnetic core of the main pole approximately crescent-shaped, the ring-shaped magnetic head 6
The same effect as when the gap 9 is formed into a crescent shape can be obtained.

Furthermore, in the above embodiment, information was recorded at high density only on the magnetic film 4 on the land 11, but information was recorded on the unused magnetic film 4 on the guide groove 10 at a recording density that allows optical reproduction. may be recorded, and upon reproduction, normal optical reproduction may be performed by detecting the rotation of the plane of polarization in the reflected light. This results in
The magnetic film 4 on the magneto-optical disk 13 is effectively utilized over the entire surface.

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

〔Effect of the invention〕

As described above, the magneto-optical recording and reproducing device according to the invention of claim 1 applies a magnetic field that is reversed according to information during recording to the magnetic film, and detects changes in the magnetic flux emitted from the magnetic film during reproducing. Since the magnetic nodal is placed opposite the magnetic film of the magneto-optical recording medium, it is possible to magnetically reproduce information recorded at high density as crescent-shaped magnetic domains, and high precision is especially required during high-density recording and reproduction. There is no need for positioning between the recording and reproducing nodes, and the effect is that high reproduction output can be easily obtained compared to the case where the recording magnetic head and the reproducing magnetic head are provided separately. . Further, there is an effect that the number of parts is reduced and the configuration of the device is simplified.

As described above, the magneto-optical recording and reproducing device according to the invention of claim 2 records and reproduces information only on the magnetic film on the land of the magneto-optical recording medium, so that the magnetic film on the guide groove Compared to high-density recording and playback of
The magnetic head can be brought close to the magnetic film. As a result, high playback output can be obtained during playback, and when recording,
This has the effect of reducing the drive current for the magnetic head. Another advantage is that the magnetic head can be made smaller, lighter, and consume less power.

In the magnetic head according to the invention of claim 3, since the gap is formed in a substantially crescent shape to match the shape of the magnetic domain of the magnetic film, when reproducing information recorded at high density as a crescent-shaped magnetic domain, there is a gap between adjacent magnetic domains. This has the effect that crosstalk and azimuth loss are less likely to occur, and high signal quality and high reproduction output can be obtained.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention. FIG. 1 is a schematic configuration diagram of the vicinity of a magnetic head of a magneto-optical disk device. FIG. 2 is a sectional view showing the general structure of a magneto-optical disk. FIG. 3 is a plan view showing the gap shape of the magnetic head. FIG. 4 is a plan view showing the gap shape of another magnetic head. FIG. 5 is a plan view showing the gap shape of another magnetic head. FIGS. 6 and 7 show conventional examples. FIG. 6 is a schematic diagram of the configuration 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), J4 is a light beam spot, and 15 is a magnetic domain. 1 Figure 13 Ta 4 Figure 4 Figure 2 '! s 5 diagram

Claims (1)

[Claims] 1. Using a magneto-optical recording medium in which guide grooves and lands are provided on a transparent substrate and a magnetic film is formed thereon, a substantially constant intensity is applied from the substrate side of the magneto-optical recording medium. In a magneto-optical recording and reproducing device that records information on a magnetic film while condensing and irradiating light such as a laser beam, a magnetic field that is reversed depending on the information is applied to the magnetic film during recording, and a magnetic field from the magnetic film is applied during reproduction. 1. A magneto-optical recording and reproducing device, characterized in that a magnetic head for detecting changes in the emitted magnetic flux is provided facing the magnetic film of the magneto-optical recording medium. 2. The magneto-optical recording and reproducing apparatus according to claim 1, wherein information is recorded and reproduced only on the magnetic film on the land of the magneto-optical recording medium. 3. A magnetic head having a gap provided opposite to a magnetic film, wherein the gap is formed in a substantially crescent shape to match the shape of the magnetic domain of the magnetic film.