JP2000260079A - Recording method and recording apparatus for magneto-optical recording medium - Google Patents

Abstract

(57) [Problem] To provide a recording method and a recording apparatus capable of forming a recording mark on a recording layer capable of stably transferring continuous recording information to a reproduction layer. SOLUTION: A recording magnetic domain 221 and the recording magnetic domain 221 are provided.
One of 1-bit binary information is assigned to a magnetic domain pattern 223 composed of a combination with a magnetic domain 222 having a magnetization in a direction opposite to that of the magnetic domain 222, and a magnetic domain composed of two magnetic domains having the same direction of magnetization as the magnetic domain 222 described above. The other of the 1-bit binary information is assigned to the pattern 224. This gives 2
The recording information 225 that is continuous for more than bits is formed on the recording layer as a continuation of a magnetic domain pattern in which a combination of a recording magnetic domain and a magnetic domain having a magnetization in a direction opposite to the recording magnetic domain is one recording information unit. From such a magnetic domain pattern, a uniform leakage magnetic field can be obtained irrespective of the position, and even if the information is continuous recording information, the information can be stably transferred to the reproducing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a recording method and a recording apparatus for recording information on a recording layer of a magneto-optical recording medium.
More specifically, the present invention relates to a recording method and a recording apparatus capable of forming a recording mark on a recording layer that can be reproduced stably even with various mark lengths when reproducing information.

[0002]

2. Description of the Related Art Optical recording media such as magneto-optical recording media are known as external memories of computers and the like. Magneto-optical recording media can handle large volumes of data such as moving images and audio, and are therefore frequently used as recording media in the multimedia age. In magneto-optical recording media, usually
Information is recorded by associating bit information "1" and "0" with the presence or absence of a recording mark. For example, an optical modulation method or a magnetic field modulation method is known as a method of recording information on a magneto-optical recording medium. I have.

In the light modulation system, information is recorded by irradiating a laser beam modulated in accordance with recording information while applying a DC magnetic field to a recording layer. In this method, information is recorded while always applying a magnetic field in a fixed direction. Therefore, in order to record information again in a portion where information has already been recorded, it is necessary to erase the information once and then record it again. On the other hand, in the magnetic field modulation method, information is recorded by applying a pulsed magnetic field according to bit data while irradiating a recording layer with a DC laser beam. in this way,
Since data can be recorded by reversing the direction of magnetization of the recording layer by a recording magnetic field in accordance with “1” and “0” of the bit information, overwriting can be performed directly. However, since the laser beam is radiated in a DC manner, the shape of the recording mark becomes a crescent shape which is long in the tangential direction of the medium as the linear velocity increases, which is disadvantageous in terms of reproduction signal processing.

As a technique for improving the magnetic field modulation method, there is known an optical magnetic field modulation method in which a magnetic field having a polarity corresponding to a recording signal is applied while irradiating pulsed light in synchronization with a recording clock. According to this method, the disadvantages of the magnetic field modulation method are eliminated, and a minute recording magnetic domain can be formed, so that high-density recording can be performed.

[0005] However, information recorded at high density has a plurality of recording magnetic domains in a reproducing light spot.
They cannot be played individually. That is, since the resolution of the reproduction light is insufficient, it is not possible to reproduce each minute recording magnetic domain. Therefore, it was necessary to reproduce a minute recording magnetic domain with a reproduction spot diameter of the current size.

As one method for solving this problem, for example, the Journal of Magnetic Society of Japan, V
ol.17 Supplement No.S1, pp.201 (1993) proposes a magnetic super-resolution technique (MSR). With this technology, even if two recording magnetic domains exist in the reproduction light spot, it is possible to reproduce the other recording magnetic domain by masking one of the magnetic domains so as not to be visible and narrowing the effective field of view. I have to. If this technique is used, the reproduction resolution can be improved without reducing the actual reproduction light spot diameter. However, even if the magnetic super-resolution technique is used, the intensity of the reproduced signal from each magnetic domain does not change.
Remained low.

The inventor of the present invention has published International Publication No. WO 98/02.
No. 878, a magnetically enlarged reproducing layer and a recording layer are provided on a substrate, and the magnetic domains transferred to the reproducing layer by applying a reproducing magnetic field while individually transferring the minute magnetic domains of the recording layer to the reproducing layer at the time of reproducing. A magneto-optical recording medium that can be reproduced on an enlarged scale has been disclosed. According to this magneto-optical recording medium,
Since the magnetic domain transferred to the magnetic expansion reproducing layer is expanded to about the spot size of light, the reproduction signal intensity is significantly increased. This technology is based on MAMMOS (Magnetic Ampli
fying Magneto-Optical System), which solves the above-mentioned problem of the magnetic super-resolution technique relating to reproduction C / N of a minute magnetic domain.

[0008]

The above-mentioned MSR and MA
In the MMOS, the information in the recording layer is transferred to the reproducing layer using the leakage magnetic field from the recording magnetic domain in the recording layer, and then the information is read from the reproducing layer. However, in such a method, when a continuous recording magnetic domain (recording mark) 227 of 2 bits or more as shown in FIG. 2 exists in the recording layer, a reproduction signal from the continuous recording magnetic domain 227 is
It was found that it was unstable compared to the shortest recording magnetic domain that existed independently. This is because the magnitude of the leakage magnetic field differs between the end portion and the central portion of the continuous recording mark formed on the recording layer, and particularly, the leakage magnetic field from the central portion is smaller than the leakage magnetic field from the end portion. This is considered to be because the information at the center of the continuous recording mark is hardly transferred to the reproduction layer. For this reason, in order to reproduce the shortest recording mark and the continuous recording mark, respectively, the power of the reproducing magnetic field and the power of the reproducing light must be strictly controlled.

Japanese Patent Laid-Open Publication No. Hei 2-101659 discloses a recording system in which the minimum recording unit for recording information is paired, and recording of binary information is performed by changing the magnetization of the minimum recording unit forming the pair. A method is disclosed. However, there is no description about recording by dividing a continuous recording magnetic domain so as to be composed of magnetic domains having different magnetization directions.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a recording method which can reliably transfer data to a reproducing layer at the time of reproducing information, even if it has various mark lengths. An object of the present invention is to provide a recording method capable of forming a mark on a recording layer.

Another object of the present invention is to provide a recording apparatus capable of recording continuous recording marks on the recording layer, which can provide stable reproduction characteristics.

[0012]

According to a first aspect of the present invention, a magneto-optical recording medium for recording information by irradiating a magneto-optical recording medium with a recording light while applying a magnetic field in a recording direction. In the recording method, 1-bit information is added to a combination of a magnetic domain having a magnetization in a recording direction and a magnetic domain having a magnetization in a direction opposite to the recording direction, or a combination of two magnetic domains having a magnetization in a direction opposite to the recording direction. When one bit of information consisting of a combination of a magnetic domain having the magnetization in the recording direction and a magnetic domain having the magnetization in the direction opposite to the recording direction is continuously recorded for two or more bits, the information is included in the information of the first bit. The size of the recording magnetic domain is adjusted so that the magnetic domain having the magnetization in the recording direction to be read is shorter than the magnetic domain having the magnetization in the recording direction included in the information of the second and subsequent bits. There is provided.

Conventionally, in order to record information on a magneto-optical recording medium, a recording layer in which the direction of magnetization is oriented in one direction (initialization direction) is recorded in accordance with binary information "0" and "1". Information is recorded by reversing the magnetization direction of the magnetic domain of the recording layer. For this reason, when “1” of the binary information is used as the recording information, when the recording data is continuous for 2 bits or more (for example, “1111”), the long magnetic mark 227 as shown in FIG. Will be formed. In such a long magnetic mark 227, the strength of the leakage magnetic field differs between the central portion 228 and the end portion 229 of the magnetic mark 227 as described in the section of the prior art. For this reason, the optimum reproducing power for reproducing the information located at the central portion 228 of the continuous mark is required for reproducing the information located at the end 229 of the continuous mark 227 and the information of the independently existing shortest mark. It is different from the optimum reproduction power, and it is difficult to reproduce information using the same reproduction power.

On the other hand, in the recording method of the present invention, as shown in FIG. 3, a magnetic domain 221 having magnetization in the recording direction (upward in the figure), such as a magnetic domain pattern 223, and a direction opposite to the recording direction (FIG. One of the binary bit information, for example, "", in combination with the magnetic domain 222 having the magnetization of (medium, downward)
1 ”is assigned to two combinations of magnetic domains having magnetizations in the opposite direction to the recording direction, such as the magnetic domain pattern 224.
For example, “0” is assigned to the other of the bit information including the value.

Here, the recording direction indicates either upward or downward perpendicular to the film surface of the recording layer. In this specification, for the sake of convenience, the upward direction is referred to as the recording direction as shown in FIGS. And A magnetic domain having a magnetization in the recording direction is referred to as “↑ magnetic domain”, and a magnetic domain having a magnetization in a direction opposite to the recording direction (initialization direction or erasing direction) is referred to as “↓ magnetic domain”.
Will be described. In binary information (digital information) represented by “1” or “0”, “1” is recorded information.

According to the recording method according to the first aspect of the present invention, the continuous recording information, for example, “1111” is a magnetic domain pattern (“↑ ↓ ↑ ↓ ↑ ↓ ↑”) composed of ↑ magnetic domains and ↓ magnetic domains.
↓ ”). In other words, even when recording continuous recording information, a magnetic domain having a magnetization in the opposite direction is always adjacent to a (minimum) magnetic domain having a magnetization in the recording direction. Therefore, the magnitude of the leakage magnetic field generated from the magnetic domain corresponding to the recording information becomes equal regardless of the magnetic domain pattern in which the magnetic domain corresponding to the recording information exists. It is possible to stably transfer the magnetization information of the recording layer to the reproduction layer regardless of the above.
For example, it is the minimum unit of a data string represented by “1” and “0”, and is read out for each 1-bit information “1” or “0” during reproduction.

In the recording method of the present invention, in order to record information on the recording layer, for example, 1-bit data "1" of binary information represented by "1" or "0" is converted into a code "10". The code may be converted into a sequence, the 1-bit data “0” may be converted into a code sequence “00”, and at least one of the recording light and the recording magnetic field may be modulated based on the code sequence converted. That is, when the recording data is “1011”, the code conversion may be performed to “10001010”. A recording signal having a waveform as shown in FIG. 9 may be generated from the code string subjected to the code conversion, and a recording magnetic field may be modulated based on the recording signal and applied.

In the present invention, of the two magnetic domains (↑ magnetic domain and ↓ magnetic domain) constituting one-bit recording information, the length of the magnetic domain (↑ magnetic domain) having the magnetization in the recording direction is defined as L1, and the length of the magnetic domain is opposite to the recording direction. The length of the magnetic domain (↓ magnetic domain) having the direction of magnetization is L
When L is 2, L2 / L1 is preferably in the range of 0.1 to 0.9. Here, the length of the magnetic domain means the length of the magnetic domain in the track direction. If the length L2 of the magnetic domain is 0.1 or more with respect to the length L1 of the magnetic domain, a stray magnetic field can be stably generated from these two magnetic domains. In addition, ↑ magnetic domain length L1 to ↓ magnetic domain length L1
Is 0.9 or less, stable reproduction characteristics can be obtained when continuous recording information is recorded.

The magnitude of the leakage magnetic field from the magnetic domain is
Usually, it depends on the size of the ↑ magnetic domain and the size of the ↓ magnetic domain adjacent thereto. Therefore, the magnitude of the leakage magnetic field from the ↑ magnetic domain corresponding to the recording information of the first bit is due to the two ↓ magnetic domains existing next to the ↑ leakage magnetic field of the ↑ magnetic domain corresponding to the recording information of the second bit. Larger than the size of. Therefore, when recording continuous recording information of 2 bits or more, first, in order to make the leakage magnetic field from the magnetic domain corresponding to the recording information of the first bit and the recording information of the second bit and thereafter uniform, It is preferable to adjust the size of the magnetic domain so that the ↑ magnetic domain corresponding to the recording information of the first bit is shorter than the ↓ magnetic domain corresponding to the recording information of the second bit and thereafter.

According to a second aspect of the present invention, there is provided a recording method of a magneto-optical recording medium for recording information by irradiating a recording light to a recording layer of the magneto-optical recording medium while applying a magnetic field in a recording direction. An area of the recording layer corresponding to one of the 1-bit binary information includes a magnetic domain having a magnetization in a recording direction and a magnetic domain having a magnetization in a direction opposite to the recording direction.
The recording layer modulates at least one of the recording light and the recording magnetic field so that an area of the recording layer corresponding to the other of the binary information of the bit is composed of two magnetic domains having magnetizations in directions opposite to the recording direction. The length of the magnetic domain having the
1. When the length of the magnetic domain having the magnetization in the direction opposite to the recording direction is L2, the dimension of the recording magnetic domain is adjusted so that L2 / L1 is in the range of 0.1 to 0.9. A featured recording method is provided.

In the recording method according to the second aspect of the present invention, of the bit information represented by "1" or "0",
The region corresponding to “1” is composed of two magnetic domain patterns (“↑ ↓”) composed of ↑ magnetic domains and ↓ magnetic domains, and the region corresponding to “0” is composed of two magnetic domain patterns (“↓ magnetic domains”) of two ↓ magnetic domains.
↓ ”) modulates at least one of the recording light and the recording magnetic field, and has magnetization in the recording direction among two magnetic domains (↑ magnetic domain and ↓ magnetic domain) constituting one bit of recording information. When the length of a magnetic domain (↑ magnetic domain) is L1, and the length of a magnetic domain (↓ magnetic domain) having a magnetization in the direction opposite to the recording direction is L2, L2 / L1 is within the range of 0.1 to 0.9. As a result, even if continuous recording information is formed on the recording layer, the magnetization information of the recording layer can be stably reproduced regardless of the continuous length of the recording information, as described in the first embodiment. It can be transferred to

According to a third aspect of the present invention, in a recording method for recording information by forming magnetic domains having different magnetization directions in a recording layer of a magneto-optical recording medium, two magnetic domains having different magnetization directions are used. One of the binary information is assigned to the magnetic domain sequence, and the two magnetization directions are the same.
The other of the binary information is assigned to a magnetic domain row composed of two magnetic domains, and the ratio of the length of one magnetic domain to the other of the two magnetic domains having different magnetization directions is 0.1 to 0. The recording method is characterized in that the information is recorded so as to fall within a range of N.9.

In the recording method according to the third aspect of the present invention, one of the binary bit information "1" and "0", for example, "1" is replaced by a magnetic domain sequence comprising two magnetic domains having different magnetization directions. And the other bit information
A magnetic domain row composed of two magnetic domains having the same magnetization direction is assigned to “0”. For example, when a magnetic domain having a magnetization in the recording direction is defined as a ↑ magnetic domain and a magnetic domain having a magnetization antiparallel to the ↑ magnetic domain is defined as a ↓ magnetic domain, A magnetic domain sequence ↑ ↓ consisting of ↑ magnetic domain and ↓ magnetic domain is assigned to “1” of the value information, and two ↓ s are assigned to “0” of the binary information.
Assign a magnetic domain sequence ↓↓ consisting of magnetic domains. Then, of the two magnetic domains having different magnetization directions, the ratio of the length of one magnetic domain to the length of the other magnetic domain is adjusted within a range of 0.1 to 0.9. Here, “1” of the binary information is made to correspond to one of the binary bit information described in the first aspect, and
By associating “0” of the value information with the other of the binary bit information, the same effect as in the first mode can be obtained.

According to a fourth aspect of the present invention, a magneto-optical recording medium for recording information on a magneto-optical recording medium having a recording layer by irradiating a recording light while applying a magnetic field in a recording direction. In the recording method of (1), when recording information of two bits or more is recorded on the recording layer, at least one bit of the recording information is composed of a magnetic domain having a magnetization in a recording direction and a magnetic domain having a magnetization in a direction opposite to the recording direction. There is provided a recording method characterized by recording information as configured.

According to a fifth aspect of the present invention, a magneto-optical recording medium for recording information on a recording layer by irradiating a recording light to a magneto-optical recording medium having a recording layer while applying a magnetic field in a recording direction. In the recording method of (1), when recording information continuous for 2 bits or more, a magnetic domain having a magnetization in a direction opposite to the recording direction is formed in a recording area of a recording layer corresponding to 1-bit recording information, A recording method is provided, wherein at least one of the recording magnetic field and the recording light is modulated.

In the recording method according to the fourth and fifth aspects of the present invention, as shown in FIG. 4, when recording single recording information corresponding to one bit, the recording information is magnetized in the recording direction. In the case where recording information consisting of two bits or more is recorded only by the isolated recording magnetic domain 441 having the
And a magnetic domain 443 having a magnetization in a direction opposite to the recording direction. Thereby, even if the recording information is continuous,
A uniform leakage magnetic field can be obtained irrespective of the position of the magnetic domain constituting the recording information, and the reproducing power margin does not become narrow due to the length of the continuous recording magnetic domain.

According to a sixth aspect of the present invention, in a recording apparatus for recording information on a magneto-optical recording medium, a light source for irradiating the magneto-optical recording medium with recording light, and a recording magnetic field for applying a recording magnetic field. When the recording data is represented by a data string composed of bit data in the recording direction and bit data in the direction opposite to the recording direction, the recording data in the direction opposite to the recording direction is interposed between the bit data. A modulator that modulates recording data so that bit data is interposed, and modulates at least one of the recording light and the recording magnetic field based on a signal from the modulator. .

The modulator of the recording apparatus according to the present invention, when the recording data is represented by a data string consisting of bit data "1" in the recording direction and bit data "0" in the direction opposite to the recording direction, The recording data is modulated so that bit data in the direction opposite to the recording direction is interposed between the bit data. And
The information is recorded by modulating at least one of the recording light and the magnetic field based on the modulated recording data. In other words, 1-bit data “1”, which is recording information, is changed to “1”.
The code is converted to a code string of "0", the 1-bit data of "0" is converted to a code string of "00", and at least one of the recording light and the recording magnetic field is modulated based on the code string converted. By using the recording apparatus of the present invention, it is possible to execute the recording method according to the first to fifth aspects of the present invention, and to achieve uniform leakage regardless of the continuous length of recording information and the position of the recording magnetic domain. Therefore, the recording apparatus of the present invention is suitable for recording on a magneto-optical recording medium including a recording layer and a reproducing layer for transferring magnetization information of the recording layer.

According to a seventh aspect of the present invention, a recording method for a magneto-optical recording medium for recording information by irradiating a recording light to a magneto-optical recording medium having a recording layer while applying a magnetic field in a recording direction. In recording information continuous for 2 bits or more, the information is recorded so that at least a magnetic domain having a magnetization in a direction opposite to the recording direction is included in a recording area of the recording layer corresponding to the information continuous for 2 bits or more. A recording method characterized by recording is provided.

In the recording method according to the seventh aspect of the present invention, when recording continuous information, magnetization in a direction opposite to the direction of the magnetic domain sequence is provided in a magnetic domain sequence (continuous recording mark) constituting the continuous recording information. The continuous recording mark is divided into a plurality of parts and recorded so that at least one magnetic domain (recording mark) is included. In order to include a magnetic domain having a reverse magnetization direction in a continuous recording mark corresponding to recording information having two or more consecutive bits, for example, a recording signal based on the recording information may be modulated. The length (mark length) of magnetic domains in different magnetization directions included in the continuous magnetic domain is not limited to the length of one bit, but may be any length.

According to an eighth aspect of the present invention, a magneto-optical recording medium for recording information on a magneto-optical recording medium having a recording layer by irradiating a recording light while applying a magnetic field in a recording direction. In the recording method of (1), when a recording mark having a mark length A is recorded on the recording layer, a magnetic field in the recording direction of the magnetic field strength H1 is applied to record a recording mark having a mark length B (B ≠ A) on the recording layer. At this time, the magnetic field strength H2 (H2 ≠ H
A recording method is provided wherein a magnetic field in the recording direction of 1) is applied.

The recording method according to the eighth aspect of the present invention modulates the magnetic field intensity of the recording magnetic field in accordance with the length of the recording mark formed on the recording layer. That is, when recording a recording mark having a mark length A, a recording magnetic field having a magnetic field intensity H1 is applied, and when recording a recording mark having a mark length B, a recording magnetic field having a magnetic field intensity H2 different from H1 is applied. For example, when the recording mark having the mark length A is the shortest recording mark, a recording magnetic field having the same magnetic field strength H1 as that of the related art is applied to form a recording mark on the recording layer. In the case of a recording mark having a mark length B (continuous recording mark), a recording magnetic field having a magnetic field strength H2 smaller than H1 is applied to form a recording mark on the recording layer. A recording mark having a mark length B recorded with a weak magnetic field strength has a state in which magnetic domains in the recording direction and magnetic domains in the opposite direction are mixed (a state in which magnetic domains in the recording direction are dispersed). In the state where the magnetic domain in the recording direction and the magnetic domain in the opposite direction are mixed,
Since the leakage magnetic field can be obtained with a sufficient magnetic field strength from any position, a sufficient leakage magnetic field can be obtained from the central portion as well as the front edge and the rear edge of the continuous recording mark, and the leakage magnetic field can be obtained over the entire continuous recording mark. Can be made uniform.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments and examples of a recording method and a recording apparatus according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

Embodiment 1 FIG. 1 schematically shows a configuration of a recording apparatus according to the present invention. The recording apparatus 101 irradiates the magneto-optical recording medium 100 with a laser beam irradiating section for irradiating the pulsed light with a cycle synchronized with the code data, and applies a magnetic field controlled during recording / reproducing to the magneto-optical recording medium 100. It mainly comprises a magnetic field application unit and a signal processing system for detecting and processing signals from the magneto-optical recording medium 100. In the laser beam irradiation section, the laser 22 is connected to a laser drive circuit 32 and a recording pulse width / phase adjustment circuit 51 (RC-PPA). The laser drive circuit 32 receives a signal from the recording pulse width phase adjustment circuit 51. To control the laser pulse width and phase of the laser 22. The recording pulse width / phase adjustment circuit 51 is a PLL circuit 3
9 generates a first synchronizing signal for adjusting the phase and pulse width of the recording light in response to a clock signal described later.

In the magnetic field application section, a magnetic coil 29 for applying a magnetic field is a magnetic coil drive circuit (M-DRIVE) 3.
4 and a magnetic coil driving circuit 3 during recording.
4 is a modulator 30 for converting recording data into a predetermined code.
And receives the code-converted data through a phase adjustment circuit (RE-PA) 31 to control the magnetic coil 29. On the other hand, at the time of reproduction, a reproduction pulse width / phase adjustment circuit (RP-PP
A) A second synchronizing signal for adjusting a phase and a pulse width is generated through 131, and the magnetic coil 29 is controlled based on the second synchronizing signal. A recording / reproduction switch (RC / RP SW) 134 is connected to the magnetic coil drive circuit 34 in order to switch a signal input to the magnetic coil drive circuit 34 between recording and reproduction.

In the signal processing system, a first polarizing prism 25 is disposed between the laser 22 and the magneto-optical recording medium 100, and a second polarizing prism 251 and detectors 28 and 281 are disposed beside the first polarizing prism 25. Have been. The detectors 28 and 281 are connected to a subtractor 302 and an adder 301 via I / V converters 311 and 312, respectively. The adder 301 is a clock extraction circuit (CSS) 37
Is connected to the PLL circuit 39 via the. Subtractor 30
Reference numeral 2 denotes a sample / hold (S / H) circuit 41 for holding a signal in synchronization with a clock, an A / D conversion circuit 42 for similarly performing analog-to-digital conversion in synchronization with a clock, and a binary signal processing circuit (BSC) 43. Is connected to the decoder 38 via the.

In the above arrangement, the light emitted from the laser 22 is converted into parallel light by the collimator lens 23, and is condensed on the magneto-optical recording medium 100 by the objective lens 24 through the polarizing prism 25. Disk 100
Is reflected by the polarizing prism 25 in the direction of the polarizing prism 251, passes through the half-wave plate 26, and is split into two directions by the polarizing prism 251. The split light is condensed by a detection lens 27 and guided to photodetectors 28 and 281, respectively. Here, the magneto-optical recording medium 1
A pit for generating a tracking error signal and a clock signal is formed on 00 in advance. Signals indicating the reflected light from the clock signal generation pits are detected by the detectors 28 and 28.
After being detected at 1, it is extracted by the clock extraction circuit 37. Next, the PL connected to the clock extraction circuit 37
In L circuit 39, a data channel clock is generated.

At the time of data recording, the laser 22 is driven by the laser drive circuit 32 to １ ／ of the data channel clock.
Is modulated at a constant frequency so as to have a period, and emits a continuous pulse light having a narrow width, and rotates the rotating magneto-optical recording medium 10.
The 0 data recording area is locally heated at equal intervals. The data channel clock is supplied to the modulator 3 of the magnetic field applying unit.
By controlling 0, a data signal of a reference clock cycle is generated. The recording data is modulated by the modulator 30, that is, code-converted. For example, it is the record information of the record data. "
"1" is converted to "10", and "0" is converted to "00".
Is converted to Further, in the modulator 30, each code after code conversion is 1/1 of the data channel clock.
The modulation is performed so as to be sent to the phase adjustment circuit 31 at twice the period. “1” or “0” of the code data signal after code conversion is sent to the phase adjustment circuit 31 to adjust the phase, and then sent to the magnetic coil driving device 34. In particular, in the phase adjustment circuit 31, the recording data "
When “1” is a continuous recording information sequence, the phase of the code data signal “10” corresponding to the first recording data “1” is adjusted so that the periods of “1” and “0” are the same. In the code data signal “10” corresponding to the next recording data “1”, “1” corresponds to ３ cycle of the data channel clock, and “0” corresponds to １ ／ cycle of the data channel clock. The phase is adjusted so that
The magnetic coil driving device 34 controls the magnetic field coil 29 to apply a magnetic field having a polarity corresponding to the conversion code data signal to a heated portion of the data recording area of the magneto-optical recording medium 100.

Next, FIG. 5 shows a schematic sectional view of a magneto-optical recording medium 100 on which information is recorded using the recording apparatus 101. The magneto-optical recording medium 100 is a MAMMOS (Ma
This is a magneto-optical recording medium for a gnetic amplifying magneto-optical system, and has a structure in which a dielectric layer 2, a magnetic domain expansion reproducing layer 3, a nonmagnetic layer 4, a recording layer 5, and a protective layer 6 are sequentially laminated on a transparent substrate 1. Have. A magneto-optical recording medium having such a structure is a MAMMOS (Magnetic Ampli) developed by the present applicant.
Based on the principle of fying Magneto-Optical System), the minute recording magnetic domain of the recording layer can be transferred to the magnetic domain expansion reproducing layer and enlarged while applying the reproducing magnetic field. In addition,
Details of the principle of MAMMOS are described in International Publication No. WO98 / 02878 shown in the section of the prior art, which can be referred to.

In the structure shown in FIG. 5, the transparent substrate 1 may be formed by molding a transparent resin material such as polycarbonate or amorphous polyolefin into a desired shape, or may be provided on one side of a glass plate formed into a desired shape. Any substrate having optical transparency, such as a substrate in which a transparent resin film to which the preformat pattern has been transferred can be used. The dielectric layer 2 is provided for causing a reproduction light beam to cause multiple interference in the film to substantially increase the detected Kerr rotation angle, and is made of a material having a higher refractive index than the transparent substrate 1. For example, it can be formed using an inorganic dielectric made of SiN. The protective layer 6 is made of the transparent substrate 1
It is for protecting the film bodies 3 to 5 laminated between the protective layer 6 and the protective layer 6 from a chemical adverse effect such as corrosion, and is made of, for example, a SiN film or a carbon film. The recording layer 5 is a perpendicular magnetization film exhibiting perpendicular magnetic anisotropy at a temperature equal to or higher than room temperature. For example, TbFeCo, DyFeCo, TbDyFeCo
An amorphous alloy of a rare earth and a transition metal, such as, for example, is most preferable. However, other known magneto-optical recording materials such as an alternately laminated body of a Pt film and a Co film or a garnet-based oxide magnetic material can also be used. The nonmagnetic layer 4 is made of, for example, SiO ₂ , AlN,
Dielectric such as SiN, Al, AlTi, Au, Cu,
It is made of a metal such as AuAl, AgAl, or a laminate of these metals and a dielectric. Magnetic domain expansion reproduction layer 3
Is a perpendicular magnetization film that exhibits perpendicular magnetization at room temperature or higher.In order to obtain a good reproduction signal during reproduction, a magnetic material such that the Kerr rotation angle increases at the maximum temperature of the medium when irradiated with reproduction light, for example, , GdFeCo.

The above-described dielectric layer 2, magnetic domain expansion reproducing layer 3, non-magnetic layer 4, recording layer 5, and protective layer 6 can be formed by a dry process such as continuous sputtering using a magnetron sputtering apparatus.

The magneto-optical recording medium 100 having such a structure
Was loaded into the recording device 101 so that laser light was emitted from the substrate 1 side, and information was recorded. The recording device 1
The laser wavelength of the optical head No. 01 is 680 nm, and the numerical aperture NA of the objective lens is 0.55. Data recording is performed by applying a laser beam to a pulse having a constant period at a linear velocity of 2.5 m / sec and modulating an external magnetic field modulated by a modulator to a predetermined code data signal at ± 200 (Oe). Using an optical pulse magnetic field modulation recording method for recording,
The measurement was performed with a laser light pulse duty of 30%. FIG.
2 shows a timing chart of a recording laser beam pulse and a recording external magnetic field with respect to a recording clock. In the upper part of FIG.
A pattern of a minute recording magnetic domain formed by such a recording method is shown. The minute recording magnetic domain indicated by a black circle corresponds to “1” of the above-described converted code data signal, and its diameter was 0.2 μm. Further, the recording magnetic domain of the first bit of the continuous recording data has a diameter of 0.2 μm and a diameter of 0.2 μm.
Subsequent bits had a diameter of 0.3 μm.

Next, the magneto-optical recording medium on which information was recorded as described above was reproduced using a reproducing device (not shown). In reproducing information, a reproduced laser beam was irradiated to each of the recorded magnetic domains in synchronization with the reproduction clock, and a reproduction magnetic field was modulated in a pulse shape and applied in synchronization with the reproduction clock. The sample-hold timing of the reproduced signal was set to coincide with the modulation timing of the magnetic field.
Then, the pattern of the recording information is “1”, “11” and “1111” (each of which is 0.4 μm, 0.8 μm,
(Corresponding to a length of 1.6 μm), the reproduction laser light and the reproduction magnetic field were changed to various powers, thereby examining a reproduction area where information can be reproduced. The results are shown in the graph of FIG.

As can be seen from the graph of FIG. 7, the area in which all the recording information of each recording pattern (recording mark length) can be reproduced is extremely wide, indicating that the reproduction power margin is extremely wide. Therefore, information recorded by the recording apparatus of the present invention can be stably reproduced even if it has various recording patterns.

COMPARATIVE EXAMPLE In the magneto-optical recording medium manufactured in the first embodiment, 1-bit recording information "1" is formed of magnetic domains in the recording direction, and the other 1-bit information "0" is recorded in the direction opposite to the recording direction. "1", "1"
The recording information of the recording patterns of “1”, “1111” was recorded, and the recording information of the recording patterns of “1”, “11”, and “1111” were 0.4 μm, 0.8 μm,.
It was formed with a mark length of 6 μm. The recorded information of these mark lengths was reproduced in the same manner as in the embodiment, and a reproduction area in which the information could be reproduced was examined. The results are shown in the graph of FIG. As can be seen from this graph, the reproduction area for the recording information of the recording pattern “1111” (the mark length is 1.6 μm) is narrow and shifted to the high power side. Also,
The area in which all of the recording marks having the mark lengths of 0.4 μm, 0.8 μm, and 1.6 μm can be reproduced is extremely small, indicating that the reproduction power margin is extremely narrow.

Embodiment 2 In this embodiment, a recording method according to the eighth aspect of the present invention is described.
This will be specifically described. FIG. 10 shows a magneto-optical disk
The dependence of the recording domain shape on the recording magnetic field intensity is schematically shown. Figure
In 10, discA is on a polycarbonate substrate
A silicon nitride layer having a thickness of 60 nm and TbFe having a thickness of 8 nm
Co recording layer, 40 nm thick Pt₈₄Co ₁₆Recording assistance
Recording medium provided with a silicon nitride layer having a thickness of 60 nm
It is. discB is a film on a polycarbonate substrate
60 nm thick silicon nitride layer, 8 nm thick TbFeCo film
Recording layer, 60 nm thick silicon nitride layer and 50 nm thick A
This is a magneto-optical recording medium having an alloy layer. The lower part of FIG.
In addition, the recording domain observed in discA and discB
A conceptual diagram is shown. In this conceptual diagram, the recorded
Inside the area to be recorded (the area where the recordable temperature is reached)
Multiple micro domains are formed, and these micro domains are recorded
The area is gradually occupied according to the strength of the magnetic field. Figure
In Table 10, disc A and d for the recording magnetic field are shown.
Indicates the occupation state of iscB by the minute magnetic domain in the above region.
And two tracks for each disc, ie two tracks
The state where a recording magnetic domain is formed is shown. D in FIG.
As can be seen from iscA, when the recording magnetic field is small
No recording magnetic domains and minute magnetic domains are formed. discB
The recording magnetic field is -100 (Oe) (about 79000 A
/ M), the worm-eating state within the outline of the recorded magnetic domain
Visible fine domain reversal occurs. Change
In addition, when the recording magnetic field is increased, many
When a minute magnetic domain is formed and a sufficient recording magnetic field is applied,
The small magnetic domains gather to form a solid recording magnetic domain. This
The magnetic field strength of the recording magnetic field applied to the recording layer
In this case, the recording magnetic domain formed is the magnetic domain in the recording direction and the opposite.
When the magnetic domains in the opposite direction are mixed (the magnetic domains in the recording direction are dispersed
State). Therefore, continuous recording marks are formed.
When forming, the intensity of the magnetic field applied to the recording
The continuous recording mark is recorded in the magnetic domain in the recording direction and the magnetic domain in the opposite direction.
Can be mixed. Magnetic domain in recording direction
And magnetic domains in the opposite direction are mixed,
Since a sufficient leakage magnetic field can be obtained from the position,
Leakage magnetic field from the center of the recording mark increases
You. This relates to magneto-optical recording as shown in FIG.
The MAMMO can be explained from the magnetic domain formation simulation.
The same recording can be performed on a magneto-optical recording medium for S.
Wear. In the simulation of FIG. 11, the mark length is 3 μm.
Schematically shows the results when forming continuous recording marks
ing. In the simulation result of FIG.
Indicates that the black area is composed of magnetic domains having magnetization in the recording direction.
Area, the white area has the magnetization in the direction opposite to the recording direction
This is an area composed of magnetic domains.

Based on the above results, the continuous recording mark
It can be seen that in order to form the magnetic domain in the recording direction and the magnetic domain in the opposite direction in a mixed state, it is sufficient to apply a recording magnetic field with a magnetic field strength different from that for recording the shortest recording mark. As a recording method, a magnetic field modulation recording method or an optical pulse magnetic field modulation recording method can be used. For example, a recording magnetic field may be applied to the magneto-optical recording medium at the timing shown in FIG. In order to make the contour of the edge portion of the continuous recording mark stand out, as shown in FIG. 12B, the recording magnetic field is increased when forming the edge portion of the continuous recording mark, and the magnetic field strength is increased in other portions. Can be weakened. Thereby, the magnetic domain in the recording direction is aggregated only at the edge portion of the recording mark, and the magnetic domain in the recording direction and the magnetic domain in the opposite direction can be mixed at the central portion of the continuous mark. As a result, it is possible to increase the leakage magnetic field from the center of the continuous recording mark. Therefore, for example, a MAMMOS having a magnetic domain expansion reproducing layer
When reproducing a magneto-optical recording medium, it is possible to reliably transfer and enlarge the information at the center of the continuous recording mark to the magnetic domain expansion reproducing layer. It is greatly reduced.

By the way, when reproducing the MAMMOS optical recording medium, it is known that a reproduction error at the central portion of the continuous recording mark occurs when the mark length of the continuous recording mark exceeds a predetermined length. . When the shortest mark is extremely short, even if it is a continuous recording mark, information can be reproduced because a sufficient leakage magnetic field is obtained from the central portion thereof. No playback error occurs. In such a case, the recording may be performed by changing the magnetic field strength of the recording magnetic field only when forming a continuous recording mark of a predetermined length or more.

The embodiments of the recording method and the recording apparatus according to the present invention have been described above, but the present invention is not limited to the above embodiments. For example, in the first embodiment, a magneto-optical recording medium having a layer structure of a substrate / dielectric layer / reproducing layer / non-magnetic layer / recording layer / protective layer is used as a magneto-optical recording medium on which information is recorded. Information was recorded by irradiating recording light from the side, but recording was performed from the side of the protective layer using a magneto-optical recording medium having a layer structure of substrate / dielectric layer / recording layer / non-magnetic layer / reproducing layer / protective layer. The information may be recorded by irradiating light.

In the first embodiment, a magneto-optical recording medium for MAMMOS is manufactured as a magneto-optical recording medium.
Recording can be performed using a magneto-optical recording medium for SR.

In the second embodiment, when the continuous recording marks are formed on the recording layer, the magnetic field strength of the recording magnetic field is controlled so as to be weaker than when the shortest recording mark is recorded. It is also possible to record information by controlling the light intensity of the recording light so that the light intensity of the recording light applied when forming the mark on the recording layer is weaker than when recording the shortest recording mark. .

[0052]

As described above, if information is recorded by using the recording method of the present invention, even if the recording information is continuous, the recording mark corresponding to each recording information of the continuous recording information can be obtained. Since a uniform leakage magnetic field can be obtained, M
It is very suitable as a method for recording information on a magneto-optical recording medium of a type such as AMMOS or MSR in which magnetization information recorded on a recording layer is transferred to a reproduction layer and the information is reproduced from the reproduction layer.

When information is recorded using the recording apparatus of the present invention, the recorded information can be stably and reliably transferred to the reproducing layer irrespective of the recording pattern. Can also be widened.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a recording apparatus according to the present invention.

FIG. 2 is a cross-sectional view of a magnetic mark formed on a recording layer by a conventional recording method and a diagram conceptually showing a state of a leakage magnetic field from the magnetic mark.

FIG. 3 is a cross-sectional view of a magnetic mark formed on a recording layer by a recording method according to the present invention and a diagram conceptually showing a state of a leakage magnetic field from the magnetic mark.

FIG. 4 is a diagram conceptually showing a state in which a continuous magnetic mark is divided by a recording method according to the present invention and a state of a leakage magnetic field from the divided magnetic mark.

FIG. 5 is a diagram showing a cross-sectional structure of a magneto-optical recording medium manufactured in an example.

FIG. 6 is a timing chart showing a relationship among a recording laser light pulse, a recording external magnetic field, and a recording magnetic domain in the recording method according to the present invention.

FIG. 7 is a diagram showing reproduction areas for recording marks of various recording patterns recorded using the recording apparatus of the present invention.

FIG. 8 is a diagram showing reproduction areas for recording marks of various recording patterns recorded by a conventional recording method.

FIG. 9 is a diagram for explaining an outline of a recording method of the present invention, and is a diagram showing a relationship between recording data, a code sequence subjected to code conversion, and a recording signal based on the converted code sequence.

FIG. 10 is a diagram schematically illustrating a state in which the shape of a recording magnetic domain formed in a recording layer of a magneto-optical recording medium depends on the strength of a recording magnetic field.

FIG. 11 is a diagram schematically showing a simulation result of a relationship between a recording magnetic field intensity and a state of a magnetic domain forming a continuous recording mark.

FIG. 12A is an example of a timing chart when the magnetic field strength of the recording magnetic field is modulated according to the recording mark length, and FIG. 12B is a timing chart when a continuous recording mark is formed. An example in which the magnetic field intensity is modulated stepwise will be described.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Dielectric layer 3 Reproducing layer 4 Nonmagnetic layer 5 Recording layer 6 Protective layer 30 Modulator 221 Magnetic domain having magnetization in recording direction 222 Magnetic domain having magnetization in direction opposite to recording direction 223, 224 Magnetic domain pattern 100 Magneto-optical recording Medium 101 recording device

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[Procedure amendment]

[Submission date] March 28, 2000 (2003.
8)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 7

[Correction method] Change

[Correction contents]

FIG. 7

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 8

[Correction method] Change

[Correction contents]

FIG. 8

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masafumi Yoshihiro 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Inventor Masaki Sekine 1-188 Ushitora, Ibaraki City, Osaka Hitachi Maxell, Inc. F-term (reference) 5D075 CC01 CC04 CC11 DD01

Claims (23)

[Claims] 1. A recording method for a magneto-optical recording medium for recording information by irradiating a recording light while applying a magnetic field in the recording direction to the magneto-optical recording medium, comprising: a magnetic domain having magnetization in the recording direction; One bit of information is allocated to a combination of a magnetic domain having a magnetization in a direction opposite to the above, or a combination of two magnetic domains having a magnetization in a direction opposite to the recording direction. When two or more bits of one-bit information consisting of a combination with a magnetic domain having a reverse magnetization are continuously recorded, two or more bits of the magnetic domain having the magnetization in the recording direction included in the information of the first bit are used. A recording method comprising: adjusting a dimension of a recording magnetic domain so as to be shorter than a magnetic domain having a magnetization in a recording direction included in information. 2. When the length of the magnetic domain having the magnetization in the recording direction is L1 and the length of the magnetic domain having the magnetization in the direction opposite to the recording direction is L2, L2 / L1 is 0.1-0. 9. The recording method according to claim 1, wherein the number is within the range of 9. 3. The recording method according to claim 1, wherein the size of the recording magnetic domain having the magnetization in the recording direction is in a range of 0.01 μm to 0.36 μm. 4. A recording method for a magneto-optical recording medium for recording information by irradiating a recording layer with a recording light while applying a magnetic field in a recording direction to the recording layer of the magneto-optical recording medium. The area of the recording layer corresponding to
A magnetic domain having a magnetization in a recording direction and a magnetic domain having a magnetization in a direction opposite to the recording direction, and a region of the recording layer corresponding to the other of the 1-bit binary information is
At least one of the recording light and the recording magnetic field is modulated so as to be composed of two magnetic domains having the magnetization in the opposite direction to the recording direction, and the length of the magnetic domain having the magnetization in the recording direction is L1, A recording method comprising: adjusting a dimension of a recording magnetic domain such that L2 / L1 is in a range of 0.1 to 0.9 when a length of a magnetic domain having reverse magnetization is L2. 5. The recording method according to claim 4, wherein a size of the recording magnetic domain having the magnetization in the recording direction is in a range of 0.01 μm to 0.36 μm. 6. A magnetic domain comprising a magnetic domain having a magnetization in the recording direction and a magnetic domain having a magnetization in a direction opposite to the recording direction.
When one of the binary information of the bits is continuously recorded for two or more bits, the magnetic domain having the magnetization in the recording direction included in the information of the first bit changes the magnetization in the recording direction included in the information of the second and subsequent bits. 6. The recording method according to claim 4, wherein the dimension of the magnetic domain is adjusted so as to be shorter than the magnetic domain. 7. A recording method for recording information by forming magnetic domains having different magnetization directions in a recording layer of a magneto-optical recording medium, comprising: a magnetic domain train comprising two magnetic domains having different magnetization directions;
One of the two types of information is assigned, and the other of the two-valued information is assigned to a magnetic domain sequence consisting of two magnetic domains having the same magnetization direction. Recording information such that the ratio of the length of the other magnetic domain to that of the other magnetic domain is in the range of 0.1 to 0.9. 8. When recording two or more bits of continuous information using a magnetic domain sequence composed of two magnetic domains having different magnetization directions from each other, a recording magnetic domain corresponding to information of a first bit is recorded.
A recording method comprising: adjusting the size of a recording magnetic domain so as to be shorter than a recording magnetic domain corresponding to recording information of the second bit and thereafter. 9. A recording method for a magneto-optical recording medium for recording information on a recording layer by irradiating a recording light while applying a magnetic field in a recording direction to the magneto-optical recording medium having the recording layer, wherein two or more bits are continuously recorded. When recording information to be recorded on a recording layer, information is recorded such that at least one bit of recording information is composed of a magnetic domain having a magnetization in a recording direction and a magnetic domain having a magnetization in a direction opposite to the recording direction. A recording method characterized in that: 10. When the length of the magnetic domain having the magnetization in the recording direction is L1 and the length of the magnetic domain having the magnetization in the direction opposite to the recording direction is L2, L2 / L1 is 0.1 to 0.1. 9
The recording method according to claim 9, wherein 11. A recording method for a magneto-optical recording medium for recording information on a recording layer by irradiating a recording light while applying a magnetic field in a recording direction to the magneto-optical recording medium having the recording layer. When recording the recording information to be recorded, at least one of the recording magnetic field and the recording light is formed such that a magnetic domain having a magnetization in a direction opposite to the recording direction is formed in a recording region of the recording layer corresponding to the 1-bit recording information. A recording method characterized by modulating the data. 12. The size of a recording magnetic domain having a magnetization in a recording direction in a recording area corresponding to 1-bit recording information is set to 0.1.
The recording method according to claim 11, wherein the distance is in a range of 01 μm to 0.36 μm. 13. The magneto-optical recording medium according to claim 1, further comprising a recording layer and a reproducing layer, wherein the magnetization information of the recording layer is transferred to the reproducing layer and the information is reproduced from the reproducing layer.
3. The recording method according to any one of 2. 14. A recording apparatus for recording information on a magneto-optical recording medium, comprising: a light source for irradiating a recording light on the magneto-optical recording medium; a magnetic field applying apparatus for applying a recording magnetic field; When represented by a data string composed of bit data in the recording direction and bit data in the direction opposite to the recording direction, the recording data is set so that bit data in the direction opposite to the recording direction is interposed between each bit data. And a modulator for modulating at least one of the recording light and the recording magnetic field based on a signal from the modulator. 15. One of the recording data is assigned to a combination of the bit data in the recording direction and the bit data in the direction opposite to the recording direction, and the other information data is assigned to the combination of the bit data in the direction opposite to the recording direction. 15. The recording apparatus according to claim 14, wherein the recording apparatus is assigned to a combination of two pieces of bit data in the directions. 16. A method for recording information by irradiating a recording light onto a magneto-optical recording medium having a recording layer while applying a magnetic field in a recording direction. At the time of recording on the recording layer, the recording magnetic domain group corresponding to the continuous information of 2 bits or more includes:
A recording method, comprising: forming a recording magnetic domain so as to include at least one magnetic domain having a magnetization in a direction opposite to a recording direction. 17. A signal based on information of two or more consecutive bits is modulated so that a recording magnetic domain group corresponding to information of two or more consecutive bits includes at least a magnetic domain having a magnetization in a direction opposite to a recording direction. The recording method according to claim 16, wherein 18. A recording method for a magneto-optical recording medium for recording information on a recording layer by irradiating a recording light while applying a magnetic field in a recording direction to the magneto-optical recording medium having the recording layer. When recording a recording mark of mark length A,
Applying a magnetic field in the recording direction with a magnetic field strength H1 and applying a magnetic field in the recording direction with a magnetic field strength H2 (H2 ≠ H1) when recording a recording mark with a mark length B (B ≠ A) on the recording layer. Characteristic recording method. 19. The recording method according to claim 18, wherein the recording mark having the mark length A is a shortest recording mark. 20. When the magnetic field strengths H1 and H2 satisfy H1>
The recording method according to claim 19, wherein H2 is satisfied. 21. The recording method according to claim 19, wherein the recording mark having the mark length B is a recording mark of recording information that is continuous for 2 bits or more. 22. The recording method according to claim 20, wherein a magnetic field in a recording direction is modulated when the recording mark having the mark length B is recorded. 23. The recording according to claim 18, further comprising modulating the light intensity of the recording light when recording the recording mark having the mark length A or B. Method.