JP2003059137A - Method and device for recording information on recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for recording by which the power consumption of a floating type magnetic head can be reduced in recording. SOLUTION: The strength of a recording magnetic field, which is to be generated from the floating type magnetic head when the linear velocity of an information recording medium is low and the floating quantity of the floating type magnetic head is small, is made smaller than the strength of a recording magnetic field to be generated when the linear velocity is high and the floating quantity of the floating type magnetic head is large. By controlling the recording magnetic field strength like this, the power consumption of the floating type magnetic head can be reduced. Further, the recording magnetic field from the floating type magnetic head is controlled so that a DC leak magnetic field, which is impressed to the recording area of the information recording medium when recording information, to be changed corresponding to the linear velocity can be canceled. Thus, the driving power of the floating type magnetic head can be further reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method and a recording apparatus for an information recording medium, and more specifically, by irradiating a laser beam onto the information recording medium and using a flying magnetic head,
The present invention relates to a method and a recording device for recording information by applying a magnetic field having a polarity corresponding to the recorded information.

[0002]

2. Description of the Related Art In recent years, with the development of information technology and the increase in the amount of information, an optical memory capable of recording a large amount of information has been used. Among optical memories, a magneto-optical recording medium capable of rewriting recorded information is being actively developed. As a method for recording information on such a magneto-optical recording medium, an optical modulation method and a magnetic field modulation method are known.

In the optical modulation method, data is recorded by irradiating a recording layer of a magneto-optical recording medium with a laser beam modulated according to recording data while applying a DC magnetic field weaker than its coercive force ( For example, JP-A-52-2
3318). In the optical modulation method, recording is always performed while applying a magnetic field in a fixed direction. Therefore, in order to record information again in an area where data has already been recorded, it is necessary to erase the already recorded area and then newly record. is there. That is, with this method, it was not possible to directly overwrite data in the already recorded area.

On the other hand, in the magnetic field modulation method, while irradiating a magneto-optical recording medium with a laser beam, a modulation magnetic field pulsed according to coded data is applied to record data (for example, Japanese Patent Laid-Open No. 51- 107121). According to this method, the data can be recorded by directly reversing the magnetization direction of the magnetic domain of the recording layer according to "0" or "1" of the bit data. Overwriting that directly writes data is possible. However, since the magneto-optical recording medium is irradiated with a laser beam in a direct current, the shape of the recording mark becomes a crescent shape that is long in the linear direction as the linear velocity increases, which is disadvantageous in terms of signal processing. Further, the magnetic domain becomes uncertain in the region where the external magnetic field is not applied at the time of switching the magnetic field, and there is a problem in terms of S / N ratio when the density is increased.

An optical magnetic field modulation method (Japanese Patent Laid-Open No. 1-292603) is known as a technique for improving the magnetic field modulation method. In this technique, a recording medium is irradiated with pulsed light (hereinafter referred to as an optical pulse) to heat the recording layer discontinuously. The recording layer is heated to the Curie temperature or higher to become paramagnetic and the old information (recorded magnetic domain) is erased. After that, the recording layer is cooled to the Curie temperature or lower, and the coercive force of the recording layer increases as the temperature decreases. At a temperature at which the coercive force of the recording layer becomes larger than the intensity of the recording magnetic field applied from the outside, the heated region of the recording layer is magnetized in the recording magnetic field direction. When the light pulse is irradiated in synchronization with the reference clock, the cooling process of the recording layer and the change in coercive force are constant with respect to the reference clock. At this time, the size of the recording magnetic domain is determined by the recording magnetic field strength. Normally, a recording magnetic field is applied to a recording medium at a constant intensity with the polarity reversed depending on the recorded information of "0" and "1", so that the marks corresponding to the respective recorded information have the same length. To record. According to this technique, it is possible to eliminate the drawbacks of the magnetic modulation method and form a recording mark of a desired size on the recording layer.

By the way, in order to perform high-speed recording and formation of minute magnetic domains, it is necessary to modulate the recording magnetic field applied to the medium at high speed. Therefore, a magnetic head using a floating electromagnetic coil that utilizes an airflow generated as the disk rotates is used. In the case of a floating magnetic head, the recording layer of the magneto-optical recording medium and the magnetic head can be brought close to each other, and therefore recording is possible even if the magnetic field strength generated from the magnetic head is small. Therefore, the drive current of the magnetic head can be reduced, and the recording magnetic field can be modulated at high speed.

[0007]

By the high-density recording technology as described above, a small-sized and large-capacity recording disk is realized, and the number of portable recording / reproducing devices using such a small-sized recording disk is increasing. Low power consumption is an important issue in portable recording / reproducing devices. For example, in a magneto-optical recording device, power is mainly consumed by a laser diode (LD), a magnetic head drive current, and a disk rotation control current during recording. In order to drive for a long time, it is desired to reduce the consumption of these electric powers.

The present invention has been made in order to meet such a demand, and an object thereof is to provide a recording method and a recording apparatus capable of surely recording information with low power consumption.

[0009]

According to a first aspect of the present invention, a method of recording information by irradiating a disc-shaped information recording medium with a laser beam and applying a magnetic field having a polarity corresponding to the recorded information. In the case of rotating the information recording medium and applying a magnetic field to the rotating information recording medium by using the floating magnetic head, the magnitude of the magnetic field generated from the floating magnetic head according to the linear velocity of the information recording medium. There is provided a recording method characterized by controlling the height.

According to the recording method of the present invention, when the floating magnetic head is levitated on the information recording medium, the magnitude of the magnetic field generated from the floating magnetic head is changed according to the linear velocity of the information recording medium. Information is recorded on a recording medium. The levitation type magnetic head floats on the information recording medium by using the airflow generated by its rotation, and therefore the distance between the surface of the information recording medium and the bottom surface of the levitation type magnetic head (hereinafter referred to as the flying height). Changes depending on the linear velocity of the information recording medium, increases when the linear velocity of the medium is high, and decreases when the linear velocity of the medium is low. In the recording method of the present invention, the magnetic field strength generated from the floating magnetic head is changed when the linear velocity of the medium is high, that is, when the flying height is large and when the linear velocity of the medium is low.
That is, the control is performed so that it is different when the flying height is small. In this way, by controlling the magnetic field strength generated from the floating magnetic head according to the linear velocity of the information recording medium, the power consumption of the floating magnetic head can be reduced. The principle will be described below.

In general, when the recording magnetic field applied to the information recording medium at the time of recording is sufficiently large, a cylindrical magnetic domain (a cylindrical magnetic domain extending in the thickness direction of the recording layer) is formed as a recording magnetic domain in the recording layer. It is formed. However, when the recording magnetic field is not large enough, the magnetization of a minute area of the recording layer is reversed and a recording magnetic domain is formed in the recording layer, but the contraction force of the magnetic domain wall of the recording magnetic domain and the leakage magnetic field from the surrounding magnetic domain are generated. Due to the balance with the expansion force due to, the inside of the recording magnetic domain becomes a mosaic shape in which magnetic domains having different magnetization directions are mixed. Such recording magnetic domains cause noise during reproduction. therefore,
Normally, it is necessary to generate a sufficient recording magnetic field from the magnetic head so that a cylindrical magnetic domain can be surely formed as a recording magnetic domain in the recording layer. It is set as the magnetic field strength.

When the flying type magnetic head is used, the flying height varies depending on the linear velocity of the information recording medium as described above. Therefore, when the flying height is high at a high linear velocity, that is, a large magnetic field strength is required. The recording magnetic field strength at that time was set as the optimum value. That is, conventionally, in order to surely form a recording magnetic domain in the recording layer, the recording magnetic field strength at a high linear velocity is set as an optimum value. Therefore, when recording is performed at a low linear velocity at which the flying height of the floating magnetic head is minimized, an excessive recording magnetic field is applied to the medium, consuming more power than necessary.

Therefore, in the recording method of the present invention, the magnetic field strength generated from the floating magnetic head is set to a linear velocity so that a magnetic field having a minimum intensity for forming a recording magnetic domain is applied to the recording layer. Control accordingly. As a result, it is possible to prevent the recording magnetic field from being excessively applied to the information recording medium, so that it is possible to prevent unnecessary power consumption of the floating magnetic head. Further, by controlling the magnetic field strength generated from the floating magnetic head in this way, a magnetic field of constant strength can be applied at any position on the information recording medium. Magnetic domains can be formed.

Further, in the recording method of the present invention, it is preferable to control so that the magnetic fields having the polarities corresponding to the codes "1" and "0" of the recording information have mutually different magnitudes. The reason will be described below.

When information is recorded on an information recording medium using a magnetic head, not only the recording magnetic field from the magnetic head but also an unintended magnetic field from the outside, for example, on the information recording medium,
A DC leakage magnetic field generated from a coil or a magnet of an actuator mounted on an optical pickup for irradiating the information recording medium with a laser beam and detecting the laser beam reflected from the information recording medium is applied.

FIG. 1A schematically shows a state in which the DC leakage magnetic field _HDC is offset to the recording magnetic field generated from the magnetic head. In the magneto-optical field modulation method, a magneto-optical recording medium is normally irradiated with an optical pulse of a constant cycle in synchronization with a reference clock, and a constant recording magnetic field strength H _W is set according to the codes "1" and "0" of the recording information. , The polarity is inverted at a constant timing T _H with respect to the reference clock and applied. However, in practice, as shown in FIG. 1 (A), since the DC leakage magnetic field H _DC to the recording magnetic field H _W is plus as offset, the effective value of the recording magnetic field, + H W ₊ H
_DC, the _-H W _{+ H DC.} Therefore, since the positive magnetic field and the negative magnetic field are applied to the information recording medium asymmetrically with respect to the case where the magnetic field strength is zero,
The lengths of the recording marks in the line direction corresponding to the codes "1" and "0" of the recording information were different.

Generally, when the information recorded on the information recording medium is reproduced, the point where the reproduced signal and the binarized detection voltage (slice voltage) intersect, that is, the signal conversion point, is the signal before recording on the information recording medium. Ideally, and should match on the time axis. However, in reality, an error occurs at the signal conversion point. The error is called jitter. The larger the jitter, the higher the probability that an error will occur during reproduction. When the mark lengths of the record marks corresponding to the record information are different, the reproduction signal conversion points are displaced on the time axis when the record marks are reproduced, so that the jitter becomes large and it becomes difficult to reliably reproduce the information.

Therefore, as shown in FIG.
The recording magnetic field generated from the head is recorded information code “0”,
Asymmetrical size (| H_W0│ ≠ │H_W1
It is conceivable to control to |). That is, FIG.
As shown in (B), the code “0” of the record information is recorded.
Sometimes magnetic field strength H_W0Of the recorded information by applying the magnetic field of
Magnetic field strength H when recording "1"_W1The magnetic field of
It Where | H_W0+ H _DC| = | H_W1-H_DC｜
The magnetic field strength H_W0And magnetic field strength
H_W1To control. Controlling the recording magnetic field in this way
The length of the recording mark corresponding to the recorded information in the line direction.
Can be about the same.

[0019] However, according to research by the inventors of the present invention, the DC leakage magnetic field H _DC generated from such as an optical pickup,
It was found that it changes depending on the linear velocity of the information recording medium.
The optical pickup is usually provided so as to face the levitation type magnetic head via the information recording medium, and the DC leakage magnetic field generated by the optical pickup is sucked into the magnetic coil of the levitation type magnetic head. Therefore, when the flying magnetic head is levitated on the information recording medium, if the linear velocity of the information recording medium is low and the flying height of the flying magnetic head is small,
Since the distance between the levitation type magnetic head and the optical pickup becomes shorter, more leakage magnetic field from the levitation type magnetic head will be absorbed by the levitation type magnetic head than when the levitation amount of the levitation type magnetic head is large. The DC leakage magnetic field applied to the medium also becomes large. That is, as conceptually shown in FIG. 2, when the linear velocity of the information recording medium increases and the flying height 23 of the flying magnetic head increases, the DC leakage magnetic field 22 decreases, and conversely, the linear leakage of the information recording medium increases. It has been found that the DC leakage magnetic field 22 increases when the flying speed 23 is low and the flying height 23 of the flying magnetic head is low.

Therefore, in the recording method of the present invention, for example,
When the codes “0” and “1” of the record information are recorded,
Magnetic field strength H generated by the floating magnetic head_W0Over
And H _W1Control to different magnetic field strength,
Change the magnetic field strength depending on the linear velocity of the information recording medium
be able to. For example, on a rotating information recording medium
When the levitation type magnetic head is levitating,
Let v be the linear velocity of the information recording medium at the floating position of the head,
The magnitude of the DC leakage magnetic field that affects the floating position is H
_DC(V), recording information “1” and “0” on the information recording medium
Field generated by the flying magnetic head when recording data
Each strength is H_W1(V) and H_W0(V)
Today, | H_W0(V) + H_DC(V) | = | H_W1(V) -H
_DC(V) | Generated from the floating magnetic head so that the relationship of
Control the magnetic field strength. Figure 2 shows the linear velocity v and DC leakage
Magnetic field H_DC(V) and the magnetic field strength H of the magnetic head
_{W 1}(V), H_W0The relationship with (v) is shown conceptually.
In this way, the magnetic field strength generated from the floating magnetic head
By controlling, it changes according to the linear velocity of the information recording medium.
The influence of the moving DC leakage magnetic field is reduced, and
Form recording marks according to recording information with desired mark length
It becomes possible. In addition, the information applied to the information recording medium
To keep the recording magnetic field strength optimum,
Recording is prevented by supplying more drive current than necessary.
It is possible to reduce the power consumption of the device.

The cause of the above-mentioned DC leakage magnetic field from the optical pickup is, for example, that the objective lens is moved toward or away from the recording film of the information recording medium in accordance with surface wobbling or warpage of the information recording medium. The coil and magnet provided in the autofocusing magnetic actuator for controlling so that the laser beam with a constant spot diameter is always focused on the film, and the optical head are moved in the radial direction on the information recording medium. There are coils and magnets provided on the carriage magnetic actuator for positioning at the desired position. In addition to these, a coil and a magnet provided in a spindle motor for rotating the information recording medium, a magnet for attaching and detaching the information recording medium, and the like are the causes of generation of the DC leakage magnetic field.

In the recording method of the present invention, the laser beam applied to the information recording medium may be an optical pulse synchronized with the reference clock. As a result, the information recording medium can be heated discontinuously, so that the recording magnetic domain can be formed with high accuracy by applying a magnetic field having a polarity corresponding to the code of the recording information in synchronization with the reference clock. .

In the present invention, when the information recording medium conforms to the CAV (Constant Angular Velocity) method or the ZCAV (Zoned CAV) method in which the rotational angular velocity is constant, the linear velocity differs depending on the radial position of the information recording medium. The magnetic field strength generated from the floating magnetic head can be controlled according to the radial position on the information recording medium on which the head is flying. For example, in an information recording medium that rotates at a constant rotational angular velocity, the inner peripheral side has a low linear velocity and the outer peripheral side has a high linear velocity, so when the floating magnetic head is positioned on the outer peripheral side of the information recording medium, The magnetic field strength generated from the head can be controlled to be larger than that when the floating magnetic head is positioned on the inner peripheral side.

According to a second aspect of the present invention, in a recording device for an information recording medium, a rotation driving device for rotating the information recording medium, and a magnetic field for floating on the information recording medium to the information recording medium. There is provided a recording apparatus comprising: a floating magnetic head for applying a magnetic field; and a controller for controlling the magnetic field strength generated from the floating magnetic head according to the linear velocity of the information recording medium.

Since the recording apparatus of the present invention is provided with the control device for controlling the magnetic field strength generated from the floating magnetic head according to the linear velocity of the information recording medium, the recording method of the first aspect of the present invention is realized. be able to. The linear velocity of the information recording medium can be obtained, for example, based on the position of the floating magnetic head on the information recording medium and the rotational velocity of the information recording medium. Since the recording apparatus of the present invention can surely record information on the information recording medium without generating extra drive power for the floating magnetic head, the power consumption of the entire apparatus can be reduced as compared with the related art. As a result, the driving time of the recording apparatus can be extended as compared with the conventional case, and it is extremely optimal as a mobile recording apparatus.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments 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.

[0027]

EXAMPLE FIGS. 3A and 3B show schematic configuration diagrams of a magneto-optical disk drive device as a specific example of a recording device according to the present invention. The magneto-optical disk drive is a drive for recording information on the magneto-optical disk, and is shown in FIG.
As shown in FIGS. 2B and 2B, the floating magnetic head 32 and the optical head 33 are arranged so as to face each other with the magneto-optical disk 31 in between. In addition to such a configuration, the magneto-optical disk drive device also forms, for example, a floating magnetic head 32 and an optical head 33 into a magneto-optical head, and the magneto-optical head is arranged directly above the magneto-optical disk 31. It can also be configured. The magneto-optical disk 31 mounted on the magneto-optical disk drive device is rotationally driven by the spindle at a predetermined rotation speed.

The magneto-optical disk 31 mounted in the magneto-optical disk drive device comprises a transparent substrate 35 and a magneto-optical recording film 34 for recording information. On one surface of the transparent substrate 35, a preformat pattern such as a guide groove and a prepit row in which track addresses and the like are recorded is formed. A magneto-optical recording film 34 is formed on the surface of the transparent substrate 35 on which the preformat pattern is formed. In FIG. 3A, the floating magnetic head 32 is arranged on the side where the magneto-optical recording film 34 of the magneto-optical disk 31 is formed, and the optical head 33 is arranged on the transparent substrate 1 side. The case where a magneto-optical disk is mounted on the magnetic disk drive is shown. In this case, the light emitted from the optical head 23 enters from the transparent substrate 35 side of the magneto-optical disk 31. Further, in FIG. 3B, the optical head 33 is arranged on the side where the magneto-optical recording film 35 of the magneto-optical disk 31 is formed, and the floating magnetic head 32 is arranged on the transparent substrate 35 side. , A case where the magneto-optical disk 31 is mounted on the magneto-optical disk drive device. In this case, the light emitted from the optical head 32 enters from the side of the magneto-optical disk 31 where the magneto-optical recording film 35 is formed.

The flying magnetic head 32 is controlled so that its magnetic field generating portion maintains a predetermined distance from the surface of the magneto-optical disk 31. It is also possible to control so that the magnetic field generating portion of the floating magnetic head 32 comes into direct contact with the surface of the magneto-optical disk 31. As a method of maintaining the distance between the magnetic field generating surface of the floating magnetic head 32 and the surface of the magneto-optical disk 31 at a predetermined interval, for example, a floating type using an airflow generated by rotational driving of the magneto-optical disk 31 is used. There is a method of floating the magnetic head 32 on the surface of the magneto-optical disk 31. Further, as described above, in the case of the magneto-optical head in which the optical head and the floating magnetic head are integrated, focusing servo is applied so that the condensing lens of the optical head is at a constant distance from the magneto-optical disk. In addition, since the tracking servo control is also performed in the radial direction of the magneto-optical disk, there is an advantage that the position of the magnetic head with respect to the magneto-optical disk can be made constant in the vertical direction and the horizontal direction.

Next, the optical system of the optical head 32 will be described. As shown in FIG. 4, the optical head 32 includes a light projecting optical system 420 and a reflecting optical system 430. The projection optical system 420 includes a semiconductor laser 41, a collimator lens 42, a beam splitter 43, and an objective lens 44. The collimator lens 42 can convert the diffused light emitted from the semiconductor laser 41 into parallel light. The beam splitter 43 can separate the incident light on the magneto-optical disk 31 and the reflected light from the magneto-optical disk 31. The objective lens 44 can focus the laser light made into the parallel light by the collimator lens 42 on the magneto-optical recording film of the magneto-optical disk 31. On the other hand, the reflection optical system 430 has the objective lens 44 and the beam splitter 43 as optical components common to the projection optical system 420, and also has a second beam splitter 47, a half-wave plate 48, and a detection lens 49. It comprises an analyzer 410 and a photodetector 411. The second beam splitter 47 can guide a part of the reflected light from the magneto-optical disk 31 to the light spot control signal detection device 46. The half-wave plate 48 can adjust the polarization plane of the reflected light from the magneto-optical disk 31. The detection lens 49 is
The reflected light whose polarization plane is adjusted by the half-wave plate 48 can be focused on the photodetector 411. The analyzer 410 separates the reflected light that has passed through the detection lens 49 into an s-polarized component and a p-polarized component. The outputs of the two photodetectors 411 are input to the differential amplifier 412, and the reproduction signal is extracted from the output terminals thereof.

The objective lens 44 is mounted on an actuator (not shown) and recorded by an output signal of the light spot control signal detector 46 so that the incident light is always focused on the recording layer of the magneto-optical disk. The distance to the layers is adjusted. The actuator includes an autofocusing magnetic actuator and a carriage magnetic actuator (not shown). The auto-focusing magnetic actuator has an objective lens 44 shown in FIG.
Can be moved toward or away from the recording film of the magneto-optical disk by following surface wobbling or warpage of the magneto-optical disk. Further, the carriage magnetic actuator can move the optical head in the radial direction of the magneto-optical disk and position it at a desired position on the magneto-optical disk. Since the autofocusing magnetic actuator and the carriage magnetic actuator are provided with coils and magnets, the DC leakage magnetic fields from these coils and magnets act on the magneto-optical recording film of the magneto-optical disk.

These DC leakage magnetic fields fluctuate when the optical head and the magnetic head are positioned at predetermined positions on the magneto-optical disk during recording. For example, when the converging point of the laser light deviates from the magneto-optical recording film due to the warp of the magneto-optical disk, a current flows through the coil of the autofocusing magnetic actuator in order to correct the deviation by moving the objective lens. At this time, the DC leakage magnetic field generated from the coil fluctuates. When the carriage magnetic actuator is driven to position the optical head and the magnetic head at a predetermined position on the magneto-optical disk, a current flows through the coil of the carriage magnetic actuator.
The DC leakage magnetic field generated from such a coil fluctuates. In addition, the magnetic field strength of the DC leakage magnetic field generated from a fixed magnet provided in the magneto-optical disk drive device such as a magnet (not shown) for attaching and detaching the magneto-optical disk is
Since it varies depending on the distance from the fixed magnet, the DC leakage magnetic field from the fixed magnet that affects the position of the optical head moving on the magneto-optical disk and the position of the magnetic head also changes.

FIG. 5 shows a schematic configuration of a control system of the magneto-optical disk drive device. As shown in FIG. 5, the magnetic coil 63 mounted on the floating magnetic head for applying a magnetic field to the magneto-optical disk 52 is a magnetic coil driving device (MD).
RIVE) 51. The recorded data 64 is
A modulator 55 converts the code into a predetermined code based on a clock signal from a PLL circuit 56, which will be described later, and then inputs the code into a pulse width / phase adjusting circuit 57. At the time of recording, the magnetic coil driving device 51 can control the magnetic coil 53 based on the signal output from the pulse width / phase adjusting circuit 57. The magnetic coil driving device 51 obtains the linear velocity of the recording portion of the magneto-optical disk from the outputs of the spindle motor control device 58 and the focusing magnetic actuator / carriage magnetic actuator control device 59, and obtains the linear velocity and the leakage magnetic field strength of the recording portion. Based on the magnetic coil 53
Drive signal can be modulated. Specifically, the amplitude of the recording magnetic field strength of positive and negative polarities is changed according to the linear velocity of the recording portion of the magneto-optical disk.

The clock signal is supplied to the optical pickup 51.
0 and a signal obtained through the I / V converter 511 based on a signal and a clock extraction circuit (CSS) 512 and a PLL circuit 56.
Is generated from.

Next, a method of recording information on the magneto-optical disk by using the magneto-optical disk drive device according to the magneto-optical field modulation recording method will be described. FIG. 6 shows a conceptual diagram of the optical magnetic field modulation recording method. At the time of recording, a semiconductor laser mounted on the optical pickup irradiates a magneto-optical disk with an optical pulse synchronized with a reference clock to discontinuously heat a predetermined area of the magneto-optical disk, and to the predetermined area, the floating magnetic head, at a constant timing T _H with respect to the reference clock, inverted to apply a recording magnetic field 61 the polarity of the magnetic field depending on the sign of the recorded information. At this time, the magnetic field strength generated from the floating magnetic head is controlled for each polarity of the magnetic field according to the linear velocity of the predetermined area of the magneto-optical disk and the DC leakage magnetic field applied to the predetermined area. In this way, recording information is formed as recording magnetic domains on the magneto-optical recording film of the magneto-optical disk. When the magnetic domains of upward magnetization and the magnetic domains of downward magnetization of the magneto-optical recording film of the magneto-optical disk are made to correspond to “1” and “0” of the recorded information, respectively, the lengths of the magnetic domains in the linear direction (mark Long) 6
Both 2 are equal. Therefore, when the information recorded on the magneto-optical disk is reproduced by using the optical head, the zero-cross interval of the reproduced signal 63 obtained by converting the electric signal based on the magneto-optical effect from the magneto-optical disk is equal to the reference clock. This is an integral multiple of the interval, and the original signal before recording on the magneto-optical disk and the signal conversion point of the reproduced signal match on the time axis.

Here, in order to investigate the relationship between the linear velocity of the magneto-optical disk and the recording magnetic field effectively applied to the magneto-optical disk, the following experiment was conducted. The samples used in the experiment were SiN, GdFeCo, Si on the substrate.
It is a magneto-optical disk provided with N and UV protective films. The drive current of the flying magnetic head [m
The recording magnetic field was applied while changing A], and a signal based on the magneto-optical effect was detected from GdFeCo by the optical head to monitor the signal amplitude [mV]. Thus, the ratio of the signal amplitude to the drive current of the floating magnetic head, that is, the signal amplitude / drive current [mV / mA] was obtained. Then, the ratio of the signal amplitude to the recording magnetic field (signal amplitude / recording magnetic field [mV / Oe]) is obtained in advance by using an electromagnet installed in the apparatus, and based on the value of the signal amplitude / recording magnetic field, The electromagnetic conversion efficiency of the floating magnetic head, that is, the ratio of the effective recording magnetic field actually applied to the GdFeCo of the magneto-optical disk to the driving current of the floating magnetic head (recording magnetic field / driving current [Oe / mA ]) Was asked. The laser wavelength of the optical head is 6
The objective lens has a numerical aperture NA of 0.6. The linear velocity was 5 m / s, 8 m / s, and 10 m / s. The reproducing power is GdFeCo of the magneto-optical disk.
1.0 m when the linear velocity is 5 m / s under the condition that the magnetic anisotropy of is heated to a temperature that changes from the in-plane direction to the vertical direction.
W, 1.3 mW when the linear velocity was 8 m / s, and 1.6 mW when the linear velocity was 10 m / s. The results are shown in Fig. 7 (A). Figure 7
From (A), it can be seen that the electromagnetic conversion efficiency of the floating magnetic head decreases as the linear velocity of the magneto-optical disk increases.

After information is recorded on the magneto-optical disk by the optical magnetic field modulation recording method using the optical head and the floating magnetic head, positive and negative DC magnetic fields are applied from the floating magnetic head to various magnetic field intensities. The information is reproduced while being applied to the magneto-optical disk at, and the value of the DC magnetic field strength at the time when the bit error rate becomes the minimum is obtained. An unintended DC leakage magnetic field from an actuator or carriage magnetic actuator) was obtained. The results are shown in Fig. 7 (B). Figure 7
As shown in (B), the DC leakage magnetic field decreases as the linear velocity increases.

FIG. 8 shows the magneto-optical disk based on the electromagnetic conversion efficiency of the flying magnetic head with respect to the linear velocity shown in FIG. 7A and the result of the DC leakage magnetic field with respect to the linear velocity shown in FIG. 7B. The relationship between the power consumption required to apply a recording magnetic field of ± 200 [Oe] and the linear velocity is shown in FIG. Note that here, it is assumed that the appearance probability of the record information “1” and “0” is 50%. The influence of the DC leakage magnetic field at a linear velocity of 10 m / s was obtained by adding the driving currents of the floating magnetic heads required to record the recording information “1” and “0” respectively to the square and adding them. It is standardized with a value considering.

Referring to FIG. 8 below, in the following description, the magnitude of the DC leakage magnetic field that changes according to the linear velocity is HDC, and the recorded information "1" and "1" are recorded in the state where there is no influence of the DC leakage magnetic field. The minimum magnetic field strengths required to record 0 "are H _W1 and H _W0 (| H _W1 | = | H _{W0, respectively)}
|). In addition, regarding the polarity of the recording magnetic field, the polarity of the recording magnetic field when recording the recording information “1” is positive, and the polarity of the recording magnetic field when recording the recording information “0” is negative.

In FIG. 8, a black square mark (hereinafter referred to as a black square mark) 81 and a white square mark (hereinafter referred to as a white square mark) 82 are both recording magnetic fields generated by the floating magnetic head. The magnetic field intensity of is modulated according to the linear velocity, and the offset component of the DC leakage magnetic field that changes according to the linear velocity is taken into consideration. Black square mark 81
Indicates a case where the magnetic field strength when recording the record information “1” and the magnetic field strength when recording the record information “0” are the same.
That is, it is a case where the positive and negative polarities of the recording magnetic field are controlled so as to have positive and negative symmetry with reference to the case where the magnetic field strength is zero. Here, as an example, when the leakage magnetic field is offset in the direction of the magnetic field when recording the recording information “1”, that is, | H _W1 + H _DC |> | H _W0 + H _DC |
The case will be described. In this case, | H _W0 + H _DC | below the minimum magnetic field strength H _W0 required to record the record information “0” by the DC leakage magnetic field HDC.
Since <| H _W0 |, it is necessary to apply a recording magnetic field of | H _W0 −H _DC | to surely record the recording information “0”. Therefore, in order to record the record information “1” and “0”, respectively, the magnetic field strengths of positive and negative polarities of the recording magnetic field are | H _W1 | + | H _DC |, | H _W0 | + | H
Controlled to _DC |.

On the other hand, the white square mark 82 is a case where the polarity of the recording magnetic field is controlled so that the magnetic field strength when recording the recording information "1" and the magnetic field strength when recording the recording information "0" are different. . That is, this is a case where the positive and negative polarities of the recording magnetic field are controlled to be asymmetrical with respect to the case where the magnetic field strength is zero. Similar to the above, when the leakage magnetic field is offset in the direction of the magnetic field when recording the recording information “1”, that is, | H _W1 + H _DC |> |
If H _W0 + H _DC |, the recording magnetic field strength is controlled to be | H _W1 −H _DC | when recording the recording information “1”, and the recording magnetic field is recorded when recording the recording information “0”. strength _| is controlled so as to | H W0 _{-H DC.} That is, when recording the recording information “1” and “0”, respectively, | H _W1 | − | H _DC |, | H _W0 | + | H _DC |
The recording magnetic field is applied. Therefore, compared with the case of the black square mark 81, the white square mark 82 can reduce the recording magnetic field strength when recording the record information "1", and therefore the power consumption becomes small as shown in FIG. ing.

From FIG. 8, by controlling the magnetic field strength of the recording magnetic field according to the linear speed of the magnetic disk, the magnetic field strength of the magneto-optical disk is ± 200 with less power consumption in the low linear speed than in the case of the high linear speed. It can be seen that the recording magnetic field of [Oe] can be applied. That is, it can be seen that when the magnetic field strength generated from the floating magnetic head is changed according to the linear velocity, the power consumption at the low linear velocity can be reduced. Especially, when the magnetic field strength when recording the record information "1" and "0" is independently controlled so that the offset of the DC leakage magnetic field that changes according to the linear velocity is canceled (white square mark), the linear velocity Is 5 m / s, the power consumption is 75 m of the power consumption when the linear velocity is 10 m / s when the magnetic field strength when recording the record information “1” and “0” is the same (black square mark). It has been reduced to%.

[0043]

According to the recording method of the present invention, the flying height of the floating magnetic head is reduced at a low linear velocity by modulating the magnetic field strength generated from the floating magnetic head according to the linear velocity of the information recording medium. As a result, it is possible to prevent a recording magnetic field having a magnetic field strength higher than necessary from being applied to the information recording medium, so that it is possible to reduce the power consumption of the floating magnetic head at a low linear velocity.

Furthermore, in order to cancel an unintended DC leakage magnetic field from the outside which changes according to the linear velocity,
The power consumption can be further reduced by modulating the intensity of the magnetic field of the polarity corresponding to the recorded information, which is generated from the floating magnetic head. Further, by controlling the recording magnetic field in this way, it is possible to form marks corresponding to the recording information with the same mark length, so that the jitter can be reduced.

In the recording apparatus of the present invention, the drive power of the floating magnetic head is appropriately set in accordance with the linear velocity of the information recording medium to prevent the drive power from being generated more than necessary. The power can be reduced. Therefore, since the driving time can be extended by the amount corresponding to the reduction in power consumption, it is extremely optimal as a mobile recording device. Further, since only a control system for controlling the magnetic field strength generated from the floating magnetic head of the existing recording device is changed or added, it is not necessary to separately provide a new mechanism, so that the structure of the recording device can be simplified. .

[Brief description of drawings]

FIG. 1 is a diagram for explaining an influence of a DC leakage magnetic field, and FIG. 1A shows a case where a recording magnetic field applied to an information recording medium is offset by the DC leakage magnetic field. (B) shows a case where the recording magnetic field is controlled so as to cancel the offset of the DC leakage magnetic field.

FIG. 2 is a diagram conceptually showing the relationship between the linear velocity of an information recording medium and the amplitude of a recording magnetic field generated from a floating magnetic head.

FIG. 3 is a schematic configuration diagram of a magneto-optical disk drive device according to the present invention. FIG. 3 (A) shows a floating magnetic head disposed on a side of a magneto-optical disk on which a magneto-optical recording film is formed and a substrate. 3B, the optical head is arranged on the side of the magneto-optical disk on which the magneto-optical recording film is formed, and the floating magnetic head is arranged on the side of the substrate. That is the case.

FIG. 4 is a schematic configuration diagram of a projection optical system and a reflection optical system of an optical head of a magneto-optical disk drive device.

FIG. 5 is a schematic configuration diagram of a control system of the magneto-optical disk drive device.

FIG. 6 is a diagram for explaining an optical magnetic field modulation recording method in an embodiment, including a reference clock, an optical pulse, a code of recording information, a recording magnetic field polarity reversal timing, a recording magnetic field,
The relationship between the recording magnetic domain (recording mark) and the reproduction signal is shown.

FIG. 7A is a graph of electromagnetic conversion efficiency of the flying magnetic head with respect to linear velocity, and FIG. 7B is a graph of DC leakage magnetic field with respect to linear velocity.

FIG. 8 is a graph showing the relationship between linear velocity and power consumption.

[Explanation of symbols]

21 recording magnetic field 22 leakage magnetic field 23 magnetic head flying height 31 magneto-optical disk 32 magnetic head 33 optical head 34 magneto-optical recording film 35 transparent substrate 41 semiconductor laser 42 collimator lens 43 beam splitter 44 objective lens 45 magneto-optical disk 46 optical point control signal Detection circuit 47 Beam splitter 48 Half-wave plate 49 Detection lens 410 Analyzer 411 Photodetector 412 Differential amplifier 61 Magnetic coil driving device 52 Magneto-optical disk 53 Magnetic coil 54 Recording data 55 Modulator 66 PLL circuit 57 Pulse width / phase Adjustment circuit 58 Spindle motor control device 59 Focusing actuator / carriage actuator control device 510 Optical pickup 511 I / V converter 512 Clock extraction circuit (C8S) 61 Recording magnetic field 62 Mark length 63 Playback signal

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Yoshifumi             Hitachima, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. (72) Inventor Shosuke Shimazaki             Hitachima, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. F-term (reference) 5D075 CC04 CF04

Claims (12)

[Claims] 1. A method of recording information by irradiating a disc-shaped information recording medium with a laser beam and applying a magnetic field having a polarity according to the recorded information, wherein the information recording medium is rotated, and the information recording medium is rotated. A recording method characterized by controlling the magnitude of a magnetic field generated by the floating magnetic head according to the linear velocity of the information recording medium when a magnetic field is applied to the floating magnetic head. 2. The recording method according to claim 1, wherein the magnitudes of magnetic fields having polarities corresponding to the recording information are controlled so as to be different from each other. 3. The recording method according to claim 1, wherein the magnitude of the magnetic field generated by the floating magnetic head is controlled based on the number of revolutions of the information recording medium. 4. The magnitude of the magnetic field generated from the floating magnetic head is controlled based on the radial position of the floating magnetic head on the information recording medium. The recording method according to any one of 1. 5. Further, the focus position of the laser beam in the optical axis direction is controlled by using a focusing magnetic actuator, a drive current flowing through the focusing magnetic actuator is detected, and the floating magnetic field is detected based on the detected drive current. The recording method according to claim 1, wherein the magnitude of the magnetic field generated from the head is controlled. 6. The carriage magnetic actuator is used to control the irradiation position of the laser beam in the radial direction of the information recording medium, the drive current flowing through the carriage magnetic actuator is detected, and based on the detected drive current. 4. The recording method according to claim 1, wherein the magnitude of the magnetic field generated by the flying magnetic head is controlled. 7. A recording apparatus for an information recording medium, a rotation driving device for rotating the information recording medium, and a floating magnetic head for levitating on the information recording medium and applying a magnetic field to the information recording medium. And a controller for controlling the magnetic field strength generated from the floating magnetic head according to the linear velocity of the information recording medium. 8. The recording apparatus according to claim 7, further comprising a laser light source for irradiating the information recording medium with laser light. 9. The recording device according to claim 7, wherein the control device controls the magnitude of a magnetic field generated from the floating magnetic head based on the number of rotations of the information recording medium. . 10. The control device controls the magnitude of a magnetic field generated from the floating magnetic head based on the radial position of the floating magnetic head on the information recording medium. 10. The recording device according to any one of items 9 to 10. 11. The recording device further comprises a focusing magnetic actuator for controlling a focal position of the laser light in the optical axis direction, and the control device further comprises a driving current of the focusing magnetic actuator. 11. The recording apparatus according to claim 7, wherein the magnitude of the magnetic field generated by the flying magnetic head is controlled. 12. A carriage magnetic actuator for moving an irradiation position of the laser light in a radial direction of the information recording medium, wherein the control device further includes: a carriage magnetic actuator based on a drive current of the carriage magnetic actuator. The recording apparatus according to any one of claims 7 to 11, characterized in that the magnitude of the magnetic field generated from the floating magnetic head is controlled.