JPH03156757A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To precisely control the impression of a required magnetic field by correcting the magnetic field for impressing upon a magneto-optical recording information carrier with an auxiliary magnet in accordance with a wobble of the magneto-optical recording information carrier. CONSTITUTION:In addition to a magnetic field generating device 18 for impressing a magnetic field in a fixed direction upon the magneto-optical recording information carrier 11 in order to overwrite the information, an auxiliary magnetic field generating device 21 is provided for changing a generated magnetic field in accordance with a relative change of a distance between the magnetic field generating device 18 and the magneto-optical information carrier 11. Consequently, even when there is distortion on the magneto-optical recording information carrier 11, and the distance between this and the magnetic field generating device 18 is varied in accordance with its rotation, the magnetic field to be impressed upon the magneto-optical recording information carrier 11 is adjusted by the auxiliary magnetic field generating device 21 to be kept constant. By this method, the stable recording of information is feasible, and the quality of a regenerative signal is improved as well.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magneto-optical recording device that uses a magneto-optical recording information carrier, that is, a magneto-optical disk as a recording medium. The present invention relates to a magneto-optical recording device that uses a magneto-optical recording information carrier having a so-called optical modulation override function, which allows new information to be directly written on old information already recorded on the media.

[Conventional technology]

The inventors of the present application previously proposed a magneto-optical recording information carrier having an optical modulation override capability, that is, a magneto-optical disk, and a magneto-optical recording device using the same in the invention of Japanese Patent Application No. are doing.

The magneto-optical recording information carrier and magneto-optical recording device according to the present invention are briefly as follows.

"a first +ff layer having perpendicular magnetic anisotropy; and a first +ff layer having perpendicular magnetic anisotropy;
In a device comprising a second magnetic layer coupled to a magnetic layer by exchange force, the second magnetic layer does not undergo magnetization reversal during recording and reproduction, and the magnetization is maintained in a constant direction, and the peak ITc, < A magneto-optical recording information carrier characterized by satisfying Tcg, fcl, Hc, >Hw, +Hb, Hc, >Hw, +Hb at room temperature. ” “Having at least two magnetic layers having perpendicular anisotropy,
A magneto-optical recording information carrier in which the magnetization direction of one layer is in a constant direction and the magnetization does not reverse during recording and reproduction, a beam emitting element that irradiates the magneto-optical recording information carrier to record and reproduce information, and the beam emitting element. A magneto-optical recording device comprising a magnetic field generator that applies a magnetic field in a fixed direction to a portion of a magneto-optical recording information carrier that is irradiated. ” A more detailed explanation will be given below with reference to the drawings.

Figure 11+a+ shows the external appearance of the magneto-optical recording information carrier proposed in the above-mentioned invention of Special Provisions Hei 1 - Kasane *Zero* Kasa, and the magneto-optical recording device for recording and reproducing information on it. tc+ is a schematic diagram showing the configuration of the main parts, and a partial cross-sectional view along the circumferential direction of the magneto-optical recording information carrier showing the state of recording and reproducing information on the magneto-optical recording quenching carrier. 3 is a graph showing characteristics of power changes of a laser beam for information recording with respect to a recording information carrier.

Figure 11 tag, ('b+, 11 irradiates the magneto-optical recording information carrier, 20 irradiates the magneto-optical recording information carrier 1N,
A laser beam 16 from a beam emitting element for recording and reproducing information is a beam spot irradiated onto the magneto-optical recording information carrier 11 when the laser beam 20 is focused by the objective lens 5 .

18 is a laser beam 20 of the magneto-optical recording information carrier 11;
This is a magnetic field generating device that generates a magnetic field such that the magnetic field applied to the irradiated area is in a fixed direction.

2 is a substrate made of glass or plastic.

7 indicates the first magnetic layer 1 among the information recorded on the first magnetic layer 13.
In this case, the region where the magnetization direction of 113 is upward in FIG. 11 is indicated as "1" in the binary data.

A first magnetic layer 13 is laminated on the substrate 2 and has perpendicular magnetic anisotropy.

14 is a second magnetic layer, which is laminated on the first magnetic layer 13,
It has perpendicular magnetic anisotropy and is coupled to the first fff layer 3 by exchange force, so that the magnetization is maintained in a constant direction without reversing the magnetization during recording and reproduction.

1st m property] W13 and the second magnetic layer 14 have Tc+ <
Te1 (where T c + + T c t are the Curie temperatures of the first magnetic layer 13 and the second magnetic layer, respectively) and at room temperature, HCl>Hwl"Htl+ Hc<H@, +Hb
(However, Hc, , Hc, are respectively the first magnetic layer 13
．． Coercive force of the second magnetic layer near room temperature + Hw+,
Hwz is the exchange coupling force of the first magnetic layer 13 and the second magnetic layer near room temperature, and Hb is the magnetic field generated by the magnetic field generator 18. There is.

Also, in order to perform the so-called light modulation gray left overwrite,
It is necessary to control the intensity of the laser beam 20 from the beam emitting element to at least three levels: high, medium, and low. Among these, in the case of a pulse beam with a high level of laser intensity and a pulse beam with an intermediate level of laser intensity, when the magnetic layer other than the magnetic layer that does not cause magnetization reversal is at a high level, the focus with upward magnetization One of the bits is formed with a bit having downward magnetization, and the other bit is formed when it is at a medium level. Information is then read using a low-level laser beam.

Next, the operation will be explained.

The magneto-optical recording information carrier 11 is rotationally driven in the direction of arrow a in the figure. As mentioned above, the magneto-optical recording information carrier 11 is composed of two magnetic layers [13, 14], and the substrate 2. First magnetic layer 13. It becomes the second magnetic layer 14.

Here, the first Vi layer 13 is a recording layer for holding the magnetization orientation representing information "0" and "1" and is also a readout layer, and the second magnetic layer 14 is provided to exhibit an override function. There is. This second magnetic layer 7i14 is also called an initialization layer, and has the function of both a conventional auxiliary layer and an initialization magnet.

Here, the characteristics of the first magnetic layer 13 and the second vL layer 14 are as follows:
Letting their Curie temperatures be Tc, , Tcz, respectively, T
There is a relationship: c, < Tc, and the respective coercive forces are Hc.

Assuming that He is the exchange coupling force of both layers and Hi (i = L2), the following relationship exists.

)(cl > Hw, + Hb −(11HCf
f1 > Hwz + Hb ・= (2) 2+1
1 holds true at a temperature between room temperature and a certain temperature T0 lower than Tc+. That is, in the temperature range between room temperature and To, the coercive force Hc+ of the first magnetic layer 13 is affected by the exchange coupling force Hw and the applied magnetic field Hb from the magnetic field generator 18 during recording.
This means that it is possible to maintain the magnetization direction representing recorded information without being influenced by the magnetization direction of the second magnetic Jii 14.

Equation (2) holds true over the entire range of operating conditions.

That is, within the range of operating conditions, the coercive force He of the second magnetic layer 14 is larger than the sum of the exchange coupling force influence i' Hw z and the magnetic field Hb applied by the magnetic field generator 18 during recording.
Therefore, once the second magnetic layer 14 is initialized, for example, if it is initialized upward as shown in FIG. 11 (bl), the magnetization will not be reversed and the upward magnetization state can be maintained.

First, the case of reproducing information recorded on the first magnetic layer 13 will be described.

As shown in FIG. 11 (bl), the first magnetic layer 13 is magnetized upward or downward in the direction corresponding to the binary code, that is, "O" in the film thickness direction.

When reproducing information, the first magnetic layer 13 is irradiated with a beam spot 16, and the irradiated portion of the first if-sensitive layer 1 is
Information is detected from the magneto-optical recording information carrier 11 by converting the magnetization direction of the magneto-optical information carrier 11 into optical information using a conventionally well-known optical force effect.

At this time, the laser intensity with which the magneto-optical recording information carrier 11 is irradiated is an intensity corresponding to point A in the graph of FIG. At this intensity, the maximum temperature rise of the first magnetic layer 13 and the second vL layer 14 in the irradiated portion of the beam spot 16 is the first
The Curie temperature Tc of the magnetic layer 13 and the second magnetic layer 14,
It does not reach Tcz. Therefore, magnetization information is not erased by irradiation with the beam spot 16.

The graph in FIG. 12 shows the temperature change characteristics of the reversal magnetic field of the first magnetic layer 13, and the graph in FIG. Each is shown in the graph.

The reversal magnetic field is the minimum required magnetic field to reverse magnetization, and Ha, -H Tsuba.

You can get 4.

In the first iff characteristic, the temperature change of the reversal magnetic field when the laser intensity (power) is set to R1 is shown in a solid line in FIG. 12, and that when the laser intensity is set to Ro is shown by a broken line.

First, when recording information "0", that is, the first magnetic layer 13
The recording operation in the case where the magnetization direction is directed downward will be explained.

When the laser beam 20 of intensity R5 is irradiated, the temperature inside the beam box H6 rises to Tr in FIG. 12. Then, when the disk rotates and the beam spot 16 is no longer irradiated with the laser beam 20, the temperature of the first magnetic layer 13 drops. As can be seen from the solid line in Figure 12, Tc
l Hb l >1(e, -Hc.) in all temperature ranges between + and room temperature.

Therefore, the magnetization direction of the first magnetic layer 13 is in the direction of the magnetic field generated by the magnetic field generator 18, that is, the direction of the bias magnetic field Hb, that is, downward.

Next, a recording operation when recording information "1", that is, when the magnetization direction of the first magnetic layer 13 is directed upward, will be described.

When the laser beam 20 of intensity R0 is irradiated, the temperature within the beam spot 16 rises to Tro as shown in FIG. Then, when the disk rotates and the beam spot 16 is no longer irradiated with the laser beam 20, the temperature of the first magnetic layer 13 decreases. As can be seen from the broken line in FIG. 12, for example, near the temperature Tp, Hb < Hw+ Hc+, so the magnetization direction of the eleventh magnetic layer 13 is the direction in which the exchange force acts, that is, the magnetization direction of the second magnetic layer 14. Turn upward.

By the above operation, at the time of override, the laser beam intensity is changed to the intensity R1 corresponding to each point C and B in FIG. 13 and the intensity R
If the intensity is modulated to 0, it is possible to override old data in real time without requiring an initialization magnet.

Note that the laser intensity corresponding to the point in FIG. 13 is the intensity when reading information as described above. At the intensity corresponding to this point A, the maximum temperature increase of the first magnetic layer 13 and the second magnetic layer 14 of the beam spot 16 reaches the Curie temperature Tc+T c t of the first magnetic layer 13 and the second magnetic layer 14. Therefore, the direction of magnetization, that is, the recorded information will not be erased by irradiation with the beam spot 16.

Next, when the laser intensity is Ro and when the laser intensity is R, the 12th
The reason why the temperature change of the reversal magnetic field of the first magnetic layer 13 differs as shown by the solid line as shown in the figure will be explained.

Although the temperature of both magnetic outer layers 13 and 14 rises due to the laser irradiation, the heat dissipation rate after that is higher in the first magnetic layer 13 than in the second magnetic layer 14. This is due to the following reasons.

(i) Since the laser beam 20 is irradiated from the first magnetic layer 13 side, the highest temperature of the first magnetic layer 13 is the same as that of the second magnetic layer 13.
It is higher than that of the magnetic layer 14, and therefore the heat dissipation rate is also high.

(ii) The first magnetic layer 13 is in contact with the substrate 2, and the first magnetic layer 13 is in contact with the substrate 2.
Heat is radiated through.

(i i i) The film thickness of the first magnetic 1i13 is extremely thin,
Therefore, the amount of heat dissipated is large.

In this way, the heat dissipation rate of the first magnetic layer 13 is higher than that of the second magnetic layer 14. Laser beam 20 with intensity R0
As a result, the temperature of the first iff layer 13 becomes Tro
The temperature of the second magnetic layer 14 at the time when the temperature of the eleventh magnetic layer 13 decreases to around Tp in FIG.
, r, and after the temperature of the first Mi layer 13 rises to Trl in FIG. 12 by the laser beam 20 of intensity R1, the temperature of the first magnetic layer 13 increases to
Ttr
+, then Tzro < Tzrl due to the difference in heat dissipation rate mentioned above.

That is, when the laser beam 20 with a large intensity R1 is irradiated, the temperature of the second magnetic layer 14 becomes higher when the temperature of the first magnetic layer 13 is around Tp. Taking into account that the exchange coupling force decreases around 1 when the magnetic layer becomes high in temperature, the exchange coupling force becomes small when the laser beam 20 with a large intensity R1 is irradiated. Therefore, there is a difference between the solid line and the broken line in the temperature change of the reversal magnetic field of the first magnetic layer 13 in FIG. 12. This causes hysteresis in magnetization with respect to temperature, making override possible.

"Example 1" The magneto-optical recording information carrier 11 is formed by sputtering or the like on the glass substrate 2, for example, by forming a first magnetic layer 13: TbxsFe-rzcos (
Film thickness: 500 layers) Second magnetic layer 14: Gd+nTb+a
It is obtained by sequentially stacking Cotz (film thickness: 1,500 layers) ferrimagnetic materials, and the magnetic layers are connected by exchange force.

The Curie temperature of the first magnetic layer 13 is about 180°C,
Second magnetic layer i14 has a magnetization reversal magnetic field of 1 kOe or more from room temperature to 250° C., and the second magnetic layer does not undergo magnetization reversal within the operating temperature range. The first magnetic layer 13 is 150°C
The exchange force becomes larger than the coercive force, and when the difference between the exchange force and the coercive force is the largest, the difference is 1 kO in terms of magnetic field.
It is about e.

The magnetic field generator 18 always generates a magnetic field of about 1 kOe in a fixed direction. The second magnetic layer 1 is formed by exposing the magneto-optical recording information carrier 11 to a magnetic field greater than or equal to the reversal magnetic field of the second magnetic layer 14.
4 is first uniformly magnetized only once, for example, in an upward direction. At this point, the direction of the magnetic field generated by the magnetic field generating device 18 is upward, and the first magnetic layer N13 and the second magnetic layer 14 have the above-mentioned relationship.

In the magneto-optical recording information carrier 11 configured as described above, optical modulation direct override is possible by modulating only the laser intensity through the above operation.

Specifically, the pit length is 0.8 to 5μ at a linear speed of 5m/sec.
m signal, the magnetic field generated by the magnetic field generator 18 is 10000e
By optically modulating the laser power to a peak power of 16IIIW and a bottom power of 51W, characteristics with an erasure ratio of 25dB or more were obtained. Laser power during playback is 1.5II
I went by W.

"Examples 2 to 8" It is sufficient that the coercive force of the second magnetic layer 14 is sufficiently large near the Curie temperature of the first m-type layer 13. 1'', various magneto-optical recording information carriers as shown in Table 1 were obtained.

Each of Table 1 uses the magneto-optical recording information carrier shown in Table 1, and when the linear velocity is 6 m/sec, the optical modulation is performed as shown in Table 2. An erasure ratio of 20 dB or more and a characteristic of about 23 to 35 dB at the optimum power were obtained, and the same optical modulation direct override as in "Example 1" was possible.

Table 2 "Example 9" As another example of the magneto-optical recording information carrier, an amorphous alloy of a transition metal and a rare earth metal exhibiting ferrimagnetism is suitable, for example, the first magnetic layer TbHFeitCO+o (film thickness 500
Good overwriting can be achieved in the same manner as in "Example 1" with the combination of composition and film thickness of second magnetic layer GdIzTb+tCOrb (thickness: 1500).

Note that each magnetic layer is made of DyFeCo, TbCo, Tb
Fe/GdCo.

The magneto-optical recording information carrier is a magnetic layer that may be made of a ferrimagnetic material such as GdDyCo, TbDyCo, or DyCo, and the second magnetic layer 14 and the first magnetic layer 13, which do not reverse magnetization in the operating region, interact only near room temperature. 11, and a dielectric layer may be included to improve signal quality and reduce oxidation corrosion of the magnetic layer 3.

[Problem to be solved by the invention]

By the way, when using a magneto-optical recording information carrier as described above, application of an external magnetic field requires more precise control than in the past in order to stabilize information recording and improve the quality of reproduced signals.

That is, although the magnetic field generating device 18 is fixed, it is rare that the surface of the magneto-optical recording information carrier 11 is maintained perfectly flat, and distortion is inevitable. Therefore, the optical head 22 is controlled to always maintain a constant positional relationship with respect to the surface of the magneto-optical recording information carrier 11 by servo control. Therefore, when the magneto-optical recording information carrier 11 rotates, the distance between the magneto-optical recording information carrier 11 when viewed from, for example, the optical head 22 or the magnetic field generating device 18 changes, and this is called surface runout.

By the way, when the above-mentioned surface deflection occurs, the distance between the magneto-optical recording information carrier 11 and the magnetic field generating device 18 changes, so the magnetic field strength at the spot 16 of the light beam on the magneto-optical recording information carrier 11 also changes. do.

Therefore, in order to stabilize information recording and improve the quality of reproduced signals, the application of an external magnetic field requires more precise control than in the past.

The present invention was made in view of these circumstances, and
An object of the present invention is to provide a magneto-optical recording device that can more precisely control the application of a required magnetic field to a magneto-optical recording information carrier.

[Means to solve the problem]

The magneto-optical recording device of the present invention includes a magnetic field generating device that applies a magnetic field in a fixed direction to a magneto-optical recording information carrier in order to override information, and a distance between the magnetic field generating device and the magneto-optical recording information carrier. The magnetic field generator is equipped with an auxiliary magnetic field generating device that changes the generated magnetic field in accordance with the relative change in the magnetic field.

[Effect]

In the magneto-optical recording device of the present invention, even if the magneto-optical recording information carrier is distorted and the distance between the magneto-optical recording information carrier and the magnetic field generating device changes as it rotates, the magnetic field applied to the magneto-optical recording information carrier is It is regulated and maintained constant by the 1 field generator.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 1(a) is a schematic diagram showing the configuration of the main part of the magneto-optical recording apparatus of the present invention, shown together with the magneto-optical recording information carrier 11.

In the figure, numeral 11 denotes the magneto-optical recording information carrier as described above, which is rotated in the direction of arrow a.

5 is an objective lens, 20 is a laser beam, 16 is a spot of the laser beam 20 on the magneto-optical recording information carrier 11,
Reference numeral 18 denotes a magnetic field generating device, which is basically the same in configuration as a conventional optical recording device.

The magneto-optical recording device of the present invention differs from conventional ones in that in addition to the magnetic field generator 18, an auxiliary magnet 21 using an electromagnet is provided between the magnetic field generator 1B and the magneto-optical recording information carrier 11. It is.

FIG. 2 is a block diagram showing the configuration of a control circuit for applying an external magnetic field of the magneto-optical recording apparatus of the present invention.

In the figure, reference numerals 21 and 22 denote the above-mentioned auxiliary magnet and optical head 22, and the optical head 22 outputs a detection signal of the distance to the magneto-optical recording information carrier 11, that is, a surface runout signal S1. The low frequency component of this surface runout signal S1 is removed by a low pass filter (LPF) 50 and input to the memo IJ51. On the other hand, the CPυ52 controls the position of the optical head 22 on the magneto-optical recording information carrier 11 using a position control signal S2, and this information is given to the memory 51 as position information (No. 3 S3. 51 stores information on how much surface wobbling occurs at which position on the magneto-optical recording information carrier 11.

The information stored in the memory 51 is given to the driver 53, and the driver 53 drives the auxiliary magnet 21 based on this information.

FIG. 3 is a graph for explaining the operation of the optical recording device of the present invention equipped with the control circuit for applying an external magnetic field configured as described above, where far and (dl are the values of the magneto-optical recording information carrier 11). The relationship between the rotational position and the amount of surface runout is expressed as fbl and te.
+ is the same (the relationship with the current applied to the auxiliary magnet 21 is (C
1 and (fl also show the relationship with the magnetic field applied to the magneto-optical recording information 1) body 11. Also, (bl mountain) and (C) indicate the state of the outer peripheral part of the magneto-optical recording information carrier 11. ,
fdl, (Ql and (fl are magneto-optical recording information carriers 11
The state of the inner circumferential portion of each is shown.

First, when starting up the apparatus, any trunks on the outer circumference and the inner circumference of the magneto-optical recording information carrier 11, for example, the outermost trunk and the innermost trunk, are selected as shown in FIG. 3, tal and f, respectively.
As shown by dl, the surface runout signal S1 is detected and stored in the memory 51 together with the position information signal S3.

When information is recorded on each track by the optical head 22, a third iJ (bl and (el) shown in FIG. As a result, the magnetic field actually applied to the magneto-optical recording information carrier 11 becomes uniform as shown by solid lines in FIG. The state indicated by the broken line in (f) shows the state when the above-mentioned processing is not performed.

Note that each track between the outermost track and the innermost track may be captured based on the data of both tracks.

Alternatively, more accurate control can be achieved by collecting data at several points between the outermost circumference and the innermost circumference when the apparatus is started up, and interpolating based on this data.

FIG. 4 shows the relationship between the magnetic field applied to the magneto-optical recording information carrier 11 by the magnetic field generator 18 and the auxiliary 611 stones 21 and the amplitude of the reproduced signal to explain another method using the magneto-optical recording device of the present invention. It is a graph.

In this method, first, when the apparatus is started up, a test pattern is recorded on a predetermined test track while changing the magnetic field applied by the auxiliary magnet 21 as shown in FIG. The intensity of the magnetic field applied by the auxiliary magnet 21 that can obtain the reproduction signal shown in FIG.

Next, other embodiments of the present invention will be described.

FIG. 5 shows the main parts of FIG. 1, namely the optical head 22. Magneto-optical recording information carrier 11. Electromagnet 21. FIG. 3 is an elevational cross-sectional view taken along a line connecting the magnetic field generators 18. FIG.

In FIG. 5, 24 indicates the objective lens 5 and the optical head 2.
2, and the magneto-optical recording information carrier 11
A magnetic sensor 23 is provided on the side. This magnetic sensor 23 is provided for the purpose of detecting the magnetic field generated by the magnetic field generator 18 and the auxiliary magnet 21.
What is important here is that although the magnetic field generator 18 is fixed and generates a constant magnetic field, the magnetic field generated by the auxiliary magnet 21 is controllable. In other words, by feeding the detection result by the auxiliary magnet 21 to the auxiliary magnet 21, the magnetic field applied to the magneto-optical recording information carrier 11 can be controlled to be constant regardless of the occurrence of surface runout. be.

FIG. 6 is a block diagram showing a configuration example of a control circuit applied to the configuration shown in FIG. 5. In the figure, 21 and 23 are m
These are the auxiliary magnet and magnetic sensor mentioned above, and 24 is a current driver that drives the auxiliary magnet 21, in other words, supplies a current for exciting the auxiliary magnet 21. The current applied to the auxiliary magnet 21 is controlled by feeding the detected value of the magnetic sensor 23 to the current driver 24.

By adopting such a configuration, even if the magneto-optical recording information carrier 11 has surface deflection, the magnetic field generated by the auxiliary magnet 21 is appropriately controlled and the magnetic field applied to the magneto-optical recording information carrier 11 is maintained. will be maintained constant.

7 shows a configuration in which a coil 25 is installed around the objective lens 5 of the optical head 22 as a magnetic sensor 23, and FIG. 8 shows a configuration in which a Hall element is attached to the objective lens 5 as a magnetic sensor 23. Next, other embodiments of the present invention will be described.

Here, a magneto-optical recording information carrier composed of four magnetic layers as shown in FIG. 9 is used.

This magneto-optical recording information carrier 11 is formed by forming a dielectric layer 81, a first magnetic layer 13 as a recording layer, on a substrate 2 made of glass or the like by sputtering or the like. Second magnetic layer 14 as a recording auxiliary layer. A third magnetic layer 83 serving as a control layer, a fourth magnetic layer 84 serving as an initialization layer, and a protective layer 82 are sequentially laminated.

The material and layer thickness of each layer are as follows.

Dielectric layer: SiNx: 65 nm First magnetic layer: TbzzFebqCoq: 80
rv second magnetic layer: Gds Dy+, FeaoCo, 5
:150nn+Third magnetic layer: Tb5oPe*a
: 20nea 4th magnetic layer: Tb3eCoto
: 40nm protective layer : SiNx
: 70n+s each of these magnetic 1'! 13.14
．． The characteristics of 83.84 are as follows.

Adjacent magnetic layers are coupled by exchange force.

The first magnetic layer 13 records and retains information.

Second magnetic layer 14. Third magnetic layer 83 and fourth r! i-sex layer 8
4 does not play the role of an information medium, but is a layer added to enable optical modulation wide left overwrite, and the fourth magnetic layer 84 is a sublayer within the operating range against temperature rise due to laser beam irradiation. This is an initialization layer that does not cause reversal of lattice magnetization and has an effect that competes with the bias magnetic field generated by the magnetic field generator 18.

The third magnetic layer 83 is a control layer for blocking the exchange force from the fourth magnetic layer 84 at high temperatures.

Tci is the Curie temperature of the first magnetic layer, Hci is the magnetic field width (corresponding to coercive force) half of the reversal magnetic field of the i-th magnetic layer, and H
If wi is the exchange force that the first magnetic layer receives from the adjacent magnetic layer, then each magnetic layer! The magnetic properties of 3.14.83.84 are as follows (al~fg1 formula).

Note that the exchange force is the i-th [a llp' of the logging loop
tiJ, and the second magnetic layer 14 and the third magnetic layer 83 are defined for magnetization reversal as shown in FIG.

Tc4〉(TCO鵠1)4-) > Tcz > T(
.

> (Tcompz) > Tc, > room temperature/fa) first magnetic N: Hw+ <Hc,; ~ room temperature...
(blHw, >Hc, H~Tc, =・(cl second magnetic layer: HN2>Hc2;~TC1...(d) Hwt<
Hct; ~Tc, -(e) Third magnetic layer: H
wt>Hcs i ~TC3-([1 4th magnetic N:HN
3 Hc4; ~ within the operating temperature range tgl (bl is at room temperature, the magnetization of the first magnetic layer 13 is not reversed by the magnetization reversal of the second magnetic layer Ji 14, (d+, (fl and tg) is at room temperature after recording) 2 magnetic layer 14. Third magnetic layer 83 and fourth magnetic] W84 magnetization direction is downward (protection [82 direction)
Indicates that they are aligned.

In the above-mentioned embodiment using two magnetic layers, the reproduced signal is greatly affected by fluctuations in the magnetic field applied during recording, but the magneto-optical recording information carrier 11 having four magnetic layers like this is used. In this embodiment, good reproduction characteristics can be obtained.

〔Effect of the invention〕

As detailed above, according to the magneto-optical recording device of the present invention, the magnetic field to be applied to the magneto-optical recording information carrier by the magnetic field generator can be corrected by the auxiliary magnet according to the surface runout of the magneto-optical recording information carrier. This makes it possible to perform constant control at all times, thereby enabling more stable information recording and improving the quality of the reproduced signal.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of the main parts of the magneto-optical recording device of the present invention, FIG. 2 is a block diagram showing the configuration of the control circuit for applying an external magnetic field, and FIG. 3 shows the operating state of the device of the present invention. Graphs for explaining, FIG. 4 are graphs showing operating states for explaining other control methods of the device of the present invention, FIGS. 5, 6,
7 and 8 are schematic diagrams showing the structure of another embodiment of the present invention, and FIG. 9 is a diagram of a magneto-optical recording information carrier having four magnetic layers used in another embodiment of the present invention. A schematic side sectional view showing the structure, FIG. 10 is an explanatory diagram of the mutual exchange force between the magnetic layers, and FIG. A schematic diagram showing the configuration, BL is a partial sectional view along the circumferential direction of the magneto-optical recording information carrier, C1 is a graph showing the characteristics of power change of a laser beam for information recording on the magneto-optical recording information carrier, 12
The figure is a graph showing the temperature change characteristics of the reversal magnetic field of the first magnetic layer of the magneto-optical recording information carrier to be processed by the apparatus of the present invention.
FIG. 13 is a graph showing the relationship between the intensity of the laser beam of the magneto-optical recording information carrier and the temperature change of the magnetic film within the laser spot. DESCRIPTION OF SYMBOLS 11... Magneto-optical recording information carrier 16... Beam spot 18... Magnetic field generator 20... Laser beam 21... Auxiliary magnet Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) At least two magnetic layers having perpendicular magnetic anisotropy are laminated, and the magnetization direction of one of the two magnetic layers is maintained in a constant direction so that the magnetization does not reverse when recording/reproducing information. a magneto-optical recording information carrier; a beam emitting element that irradiates the magneto-optical recording information carrier to record information; a magnetic field generator that applies a magnetic field to a portion of the magneto-optical recording information carrier that is irradiated by the beam emitting element; A magneto-optical recording device comprising: an auxiliary magnetic field generator that changes the intensity of the generated magnetic field to compensate for changes in the magnetic field applied to the magneto-optical recording information carrier by the magnetic field generator.