JP2658866B2 - Magneto-optical storage method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical storage method and, more particularly, to overwriting by magnetic field modulated light.
The present invention relates to a possible magneto-optical disk drive.

[0002]

2. Description of the Related Art Conventionally, as an overwritable magneto-optical disk device, IEE Transaction on Magnetics (IEEE Transactions Magnetics) has been proposed.
n onMagnatics) MAG-20. Volume 5p. 10
13 (1984), a method using two light spots, or a method using JP-A-51-107121.
No., JP-A-59-215008, and JP-B-60-488.
No. 06, a method of modulating a magnetic field applied to a recording film in accordance with information to be recorded, and the like. The present invention particularly relates to a magneto-optical storage device using the latter magnetic field modulation method.

[0003]

Conventionally, in an example of overwriting by a magnetic field modulation method, an electromagnetic coil for generating a magnetic field is provided on a disk to apply a modulated magnetic field. The distance between the two was fixed to about 0.1 mm to 0.5 mm. In this case, the recording frequency is lower than 0.5 MHz, and there is a problem that signal recording at a frequency of about several MHz cannot be performed.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide a magneto-optical storage device capable of recording a signal of about several MHz and having both the overwrite function, which is an advantage of a magnetic disk, and the high density and large capacity, which are advantages of an optical disk.

[0005]

In order to achieve the above object, the present invention is characterized in that an optical head and a magnetic head are opposed to each other with a record carrier interposed therebetween, and a floating magnetic head is used as the magnetic head. This flying magnetic head has a large flying height (1 μm) even at a low linear velocity with a head core having a wide effective magnetic field application area (about 0.2 mm × 0.5 mm).
Above) consists of a slider. Then, light is irradiated from the substrate side of the record carrier by the optical head, and a magnetic field is applied by the magnetic head from the magneto-optical recording film side.

Specifically, a disc-shaped record carrier having a transparent substrate, a magneto-optical recording film on the transparent substrate, and a protective film on the magneto-optical recording film is used, and the polarity is inverted or the intensity is modulated according to the recorded information. A magneto-optical storage method for recording information by applying a magnetic field to the magneto-optical recording film from the protective film side and irradiating the magneto-optical recording film with laser light from the transparent substrate side. The magnetic field application region applied to the magneto-optical recording film has a width of 100 to 200 times the recording track width in the radial direction of the record carrier.

According to another feature of the present invention, a protective film having good sliding resistance is formed on the side of the magneto-optical recording film facing the magnetic head, for example, with a thickness of 1 to 20 μm.

[0008]

The flying magnetic head used in the present invention has a much wider effective magnetic field application area than the conventional magnetic head. For example, if the effective magnetic field is about 0.2 mm × 0.5 mm, the position of the narrowed spot and the magnetic head are aligned. And it is stable against temperature changes and vibrations. Since the magnetic field application region has a width of 100 to 200 times the recording track width in the radial direction of the record carrier, the light spot does not deviate from the magnetic field application region due to the eccentricity of the disk or the like.

If the flying height of the magnetic head is 1 μm or more, so-called head crash due to dust or the like hardly occurs, and the device can be used in the atmosphere. Furthermore, when a head core having a wide effective magnetic field application region as described above is used, the magnetic field intensity hardly attenuates even at a position separated by 10 to 20 μm from the end surface of the head core, so that the surface of the magneto-optical recording film is about 5 to 10 μm. A thick protective film can be formed. In addition, unlike conventional coating type magnetic disks, the protective film can be coated purely for the protective effect without containing magnetic powder, so that the protective coating has extremely high durability and further enhances environmental resistance and reliability. Can be improved.

In recording information, the magneto-optical recording film is irradiated with high-power laser light from the substrate side by an optical head, and at the same time, a modulated magnetic field whose polarity is inverted by the magnetic head according to the recorded information is applied from the magneto-optical recording film side. This is done by applying. As a result, a new signal can be overwritten while erasing an old signal. The recording density is determined by the size of the light spot. That is, it is possible to realize a magneto-optical storage device having both the high density and large capacity of an optical disk and the overwrite function of a magnetic disk without substantially impairing the non-contact point which is a feature of optical recording.

[0011]

FIG. 1 shows a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a magneto-optical disk as a rotating record carrier, which has a magneto-optical recording medium 101 having a magneto-optical effect and a protective film 102 on a disk-shaped transparent substrate 103. For example, light emitted from a light source including the semiconductor laser 2 is converted into a parallel light beam by the collimator lens 3, and is incident on the aperture lens 5 via the beam splitter 4. The light beam focused by the lens 5 is incident on the disk from the disk substrate 103 side and forms a minute spot having a diameter of about 1 μm on the recording film 101. The aperture lens 5 follows the vertical vibration of the disk 1 so that the focal point always comes on the recording film, and follows the eccentricity of the information recording track on the disk so that the spot always comes on the desired track. It is attached to the actuator 6. The reflected light from the disk 1 passes through the aperture lens 5 and is reflected by the beam splitter 4. The beam splitter 7 transmits the light to a magneto-optical signal detection optical system 8 and a light point control signal detection optical system 9 for detecting a focus shift and a track shift. Be guided.

FIG. 1 shows an example of the magneto-optical signal detection system 8. This is a differential signal detection method using a λ / 2 plate 801 and a polarization beam splitter 803. The light that has entered the magneto-optical signal detection optical system 8 passes through the λ / 2 plate 801 and the lens 802, is separated into sp and p polarization components by the polarization beam splitter 803, and is transmitted to the photodetectors 804 and 805, respectively. It is collected. The signal converted into an electric signal by the two photodetectors is differentiated by the differential amplifier 10 and obtained as a magneto-optical signal.

The magnetic head 12 is arranged on the recording film side so as to face the optical head 11 with the disk 1 interposed therebetween. In FIG. 1, for the sake of explanation, the magnetic head is rotated by 90 ° in the disk surface from the actual arrangement, and is enlarged in a bird's-eye view. The magnetic head 12 includes a coil portion for applying a magnetic field to the recording film and a slider portion for floating the entire head, as described later, and is floated by air pressure due to the rotation of the disk during rotation of the disk. The flying height is 1 μm or more (preferably 2 μm or more). At this level of flying height,
A head crash due to dust or the like, which is a problem in the magnetic disk, does not occur, and it is possible to use the apparatus in the atmosphere and replace the medium.

The magnetic head 12 is pressed against the disk 1 by a support spring 13 with a load of about 5 to 10 g. At the start and stop of the rotation of the disk, a so-called CSS (C
Ontact Start) method or a method in which the magnetic head is separated from the disk until the number of rotations of the disk becomes a constant value may be used. Just disk 1
In order to replace the magnetic head 12, a moving mechanism 16 for moving the magnetic head 12 up and down is required regardless of the above two methods.

The magnetic head 12 is further integrally connected with the optical head 11 and a supporting arm 15 so as to be able to interlock with the optical head. A magnetic head. It is not always necessary to integrate the two as shown in the figure, but if the recording position is moved in the radial direction of the disk if they are not integrally combined, a means for keeping the distance between them and the magnetic head just above the light spot A magnetic head moving means for installing the head is required.

The optical head 11 is moved in the disk radial direction by, for example, a linear motor or a step motor.

FIG. 2 shows a method of recording information. In order to record information, the semiconductor laser 2 is made to continuously emit light at a high output as shown in FIG.
Is heated to a temperature close to the Curie temperature, and the coercive force of the portion irradiated with light is reduced. At this time, the magnetic head 12 is driven by the magnetic head driving circuit 14 to record information (FIG. 2).
The modulated magnetic field whose polarity has been inverted according to (a)) (FIG. 2)
(C)) is applied to the magneto-optical recording film 101 to record information. The recording state is shown in FIG. If the applied magnetic field strength needs to be changed in order to keep the recording conditions constant regardless of the inner and outer circumferences of the disk and fluctuations in the laser output,
In addition to the polarity inversion, a DC bias component is added to the intensity modulation or the magnetic field. According to this method, even if a new recording is performed on a portion where information is recorded, the old recorded information does not remain, and the old information can be erased by overwriting, that is, overwriting information. Becomes

Here, embodiments of the magnetic head and the disk, which are main components of the embodiment, will be described in detail.

As the magnetic head 12, a floating magnetic head having a large flying height even with a low linear velocity and a wide effective magnetic field application area is used. The flying height is 1 μm or more (preferably 2 μm or more) from the viewpoint of preventing a head crash due to dust or the like,
From the viewpoint of the alignment between the light spot and the magnetic head, the effective magnetic field application area of the head core is 0.1 mm × 0.1 mm or more and 1 mm.
× 1 mm or less, preferably 0.1 mm × 0.1 mm or more, 0.2 m
m x 0.5 mm or less.

FIG. 3 shows an example of a magnetic head used in the present invention. FIG. 3C is a diagram showing a slider sliding surface.
The entire surface facing the disk is a sliding surface, and two substantially circular through holes are provided on the center axis AA 'of the slider 301 along the disk traveling direction. As a result, the sliding surface area contributing to flying can be increased as compared with the conventional magnetic head shown in FIG. 4, so that the flying height increases. In addition, the air pressure distribution for floating is as shown at the side of FIG. 4C, and the slider is supported at four points P _{1 to} P _{4 in} the figure, and the pitching or the rolling is prevented. And stable floating can be realized. The through hole may be a substantially circular concave portion. At this time, the depth of the recess is shown in FIG.
Is set so as to obtain the air pressure distribution shown in FIG. If this slider is used, for example, the outer dimension of the sliding surface is 3 mm x 4 m
In the case of m, a hole diameter of 0.6 mm, and a load of 5 g, a flying height of 2 μm can be obtained even if the disk peripheral speed is about 3 m / sec as shown in FIG. In the above example, the number of the circular concave portions or the through holes is two, but may be one, as shown in FIG. Further, the shape of the concave portion or the hole need not necessarily be circular, such as oval or rectangular.

The magnetic field applied to the recording film is applied by a coil 302 provided at the end of the air outflow end. The coil core is a magnetic material such as Mn-Zn ferrite, for example, and may be formed integrally with the slider, or may be formed separately from the magnetic core and the coil portion and then combined with the slider. In particular, in the latter case, the slider need not be a magnetic material such as Mn-Zn ferrite, and may be a non-magnetic material such as ceramic.

When a magnetic material is used as the slider material, the leakage magnetic field of the actuator 6 is concentrated on the slider side, and the net magnetic field intensity applied to the recording film is reduced, or the magnetic field generated in the magnetic core portion 302 and the leakage magnetic field are reduced. In some cases, the magnetic head vibrates due to the interaction with the magnetic head, but using a non-magnetic slider also has the effect of preventing the above phenomenon.

The position where the magnetic field is applied does not necessarily need to be at the outflow end, but may be arranged inside the slider as shown in FIG. Further, in this case, it is also effective to use a non-magnetic ceramic or the like as the slider 301 and use a magnetic material only for the coil core 302 or an air-core coil. With air core coil,
Since the inductance of the entire magnetic head can be reduced, there is an effect that the frequency response of the magnetic head can be improved as described later.

The area of the effective magnetic field application area at the tip of the coil is determined by (i) the positioning accuracy of the magnetic head, (ii) the amount of disk eccentricity, (ii) the frequency response of the magnetic head, and the like. ii) A larger area is required, but the frequency response of (iii) is deteriorated due to an increase in inductance. For example, 0.2mm in the circumferential direction
It is preferably about 0.5 mm to 0.1 mm × 0.1 mm in the radial direction. The former can cope with a recording frequency of 3 to 5 MHz, and the latter can cope with a recording frequency of about 5 to 10 MHz.

In the former example, a larger area is taken in the radial direction than in the disk circumferential direction. This is to prevent the light spot from moving out of the effective magnetic field application area even if the light spot moves in the radial direction due to the disk eccentricity. As shown in FIG. 1, the magnetic head 12 is fixed to the optical head 11 by the support arm 15 and moves in the disk radial direction in conjunction with the optical head. If the magnetic head 12 is provided with a mechanism that follows the disk eccentricity, the magnetic field application area can be reduced. However, in this case, a position control mechanism for the magnetic head is required separately from the optical head. However, the device becomes complicated and expensive. Therefore, in the present embodiment, in order to make the apparatus configuration simple and inexpensive, a measure is taken by providing an effective magnetic field application area wider in the radial direction than in the disk circumferential direction. Further, when the optical head is moved discontinuously by, for example, a step motor or the like, the amount of movement of the narrowed spot in the radial direction becomes larger than the disk eccentricity. In a magnetic disk or a floppy disk, the magnetic field application region by the magnetic head corresponds to the recording track width, but in the case of the magnetic head used in the magneto-optical disk as in this embodiment, the magnetic field application region is It has a width of 100 to 200 times the recording track width.

The magnetic field application area as described above is 50 to 100 times wider than a magnetic head for a magnetic disk. Therefore, the ratio of the decrease of the perpendicular component of the magnetic field to the distance from the head is much smaller than that of the magnetic disk head. For example, in the case of a magnetic head having a magnetic field application area of 0.5 mm × 0.2 mm, as shown in FIG.
Even at a position separated by 0 μm, the reduction of the vertical component of the magnetic field is 2
About 3%.

If the magnetic field application area is widened, the decrease in the magnetic field intensity at a position several tens of μm from the end face of the magnetic head can be made smaller than in the example shown in FIG. In order to realize a recording frequency of several MHz, the magnetic field application area is preferably about 0.5 mm × 0.2 mm or less, and the distance between the magneto-optical recording film and the magnetic head is 3 mm.
It is preferable that the thickness be 0 μm or less. The above points are important in determining a disk structure in consideration of sliding resistance. Further, the fluctuation of the magnetic field strength due to the vertical movement of the magnetic head 12 is 1
Even if it is about μm, there is no problem as in the case of a magnetic disk.

FIG. 9 shows an example of the structure of a disk used in the present invention. This disc is for single-sided recording, and
The light is irradiated from the side, and a magnetic field is applied from the recording film 903 side. The substrate 901 is made of glass or plastic having a thickness of about 1.2 mm. With a magneto-optical recording film layer (eg, TbFeCo perpendicular magnetization film) 903 having a thickness of about 1000 ° interposed therebetween,
On the substrate side, an enhancement film (approximately 1
902 (e.g., Si ₃ N ₄ , SiO, etc.) 902 is provided, and a protective film (approximately 2000 μm, eg, Si ₃ N ₄ , SiO, etc.) 904 is provided on the other surface to improve corrosion resistance and oxidation resistance. . A protective coat 905 for improving the sliding resistance with the magnetic head is formed thereon on the order of 1 to 20 μm, preferably about 5 to 10 μm. At this time, the recording film 903
The distance between the magnetic head 12 and the magnetic head 12 is about 10 to 20 μm, but unlike the magnetic disk, the magnetic field strength does not decrease at such a distance as shown in FIG.

As the protective coat 905, for example, an ultraviolet curing resin is used. A so-called filler such as Al ₂ O ₃ or a lubricant may be mixed in the ultraviolet curable resin. For example, when a spherical sliding test was conducted using a UV-curable resin mixed with a filler, it was possible to achieve 1,000,000 or more slidings. In the case of a magneto-optical disk, recording / reproducing /
Since the erasing characteristics are not affected, the thickness of the protective coating can be increased as described above, and the life of the disk or the environmental resistance can be improved, and the reliability of the device can be improved.

Further, the disk 1 is replaceable and is housed in a cartridge 906 as shown in FIG. In the cartridge 906, a dustproof mechanism 907 such as linen paper is provided to remove dust adhering to the protective coat, facing the protective coat of the disk.

Next, FIG. 11 shows a second embodiment of the present invention. This is an example in which a laser array in which two laser chips are housed in one package is used as the laser light source 2. However, the support spring 13, the support arm 15, and the magnetic head moving device 16 shown in FIG. 1 are omitted for simplicity. In FIG. 2A, the positional relationship of the narrowed spots on the disk is rotated by 90 ° in the disk surface for the same explanation as in FIG. As shown in FIG. 1B, a semiconductor laser array in which two laser chips LD1 and LD2 having different wavelengths are mounted in one package with their active layers facing each other is used as a light source. LD1 has a wavelength of 780 nm
Low-power, low-noise laser used for reproducing magneto-optical signals and controlling light spots. On the other hand, the LD 2 is a high-power laser having a wavelength of 830 nm, and is used for recording and erasing signals. On the other hand, the LD 2 is a high-power laser having a wavelength of 830 nm, and is used for recording and erasing signals. The positional relationship between the light spots SP1 (780 nm wavelength) and SP2 (860 nm wavelength) formed by both laser light sources on the disk is on the same track as shown in FIG. Thereby, at the same time as recording at the spot SP2, an error check can be performed at the spot SP1. The error check is performed by comparing the recording signal and the magneto-optical signal reproduced by the spot SP2 with the comparator 17. The result of the comparison is input to the controller 18, and when a mismatch or an error occurs between the two signals, an operation such as re-recording is performed. In this embodiment, the signal before the input to the magnetic head driving circuit 14 is used as the original recording signal to be compared.
May be used as the output of the magnetic head.

Conventionally, a magneto-optical disk requires one rotation of the disk in the order of erasing, recording, and checking to rewrite recorded information, for a total of three rotations. Since the above three operations can be performed in one rotation, the effective data recording time can be greatly reduced.

[0034]

As described above, according to the present invention, it is possible to increase the density and capacity of an optical disk without significantly impairing the characteristics of optical recording such as non-contact recording, reproduction and erasure.
It is possible to realize a magneto-optical recording device having both a high-speed and overwrite function of a magnetic disk, which is extremely effective for improving the performance of an optical disk.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an information recording operation according to the present invention.

FIG. 3 is a diagram showing a structural example of a magnetic head used in the present invention.

FIG. 4 is a three-view drawing showing a magnetic head structure.

FIG. 5 is a graph showing an example of flying characteristics of a flying magnetic head used in the present invention.

FIG. 6 is a plan view showing an example of a magnetic head used in the present invention.

FIG. 7 is a three-view drawing showing an example of a magnetic head used in the present invention.

FIG. 8 is a graph showing an example of a magnetic field intensity distribution generated by a magnetic head used in the present invention.

FIG. 9 is a sectional view showing a structural example of a magneto-optical disk used in the present invention.

FIG. 10 is a diagram showing a structural example of a disk cartridge.

FIG. 11 is a block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Disk, 2 ... Semiconductor laser, 5 ... Aperture lens, 8 ... Magneto-optical signal detection optical system, 9 ... Light point control signal detection optical system, 11 ... Optical head, 12 ... Magnetic head, 301 ...
Slider, 302: coil, 901: disk substrate, 9
03: magneto-optical recording film, 905: protective coat, 14: wavelength separation filter, LD1: laser chip for signal reproduction, LD
2. Laser chip for signal recording.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toyoharu Okwaki 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Inside the Central Research Laboratory of the Works (72) Inventor Yoshinori Takeuchi 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Inside the Machinery Research Laboratory, Hitachi, Ltd. ) References JP-A-63-217548 (JP, A)

Claims (4)

(57) [Claims] 1. A transparent substrate, a magneto-optical recording film on the transparent substrate,
Using a disc-shaped record carrier having a protective film on the magneto-optical recording film
Inverted or intensity modulated according to recorded information
When a magnetic field is applied to the magneto-optical recording film from the protective film side
In both cases, the laser light is applied to the magneto-optical recording from the transparent substrate side.
Magneto-optical recording that records information by irradiating the film
The method of recording and erasing information
The magnetic field application region applied to the recording film is half of the record carrier.
Has a width of 100 to 200 times the recording track width in the radial direction
The magnetic field is applied by magnetic field applying means,
Magnetic field at a position 100 μm away from the end face of the adding means
A magneto-optical storage method wherein the reduction of the direct component is 30% or less. 2. A transparent substrate, a magneto-optical recording film on the transparent substrate,
Using a disc-shaped record carrier having a protective film on the magneto-optical recording film
Inverted or intensity modulated according to recorded information
When a magnetic field is applied to the magneto-optical recording film from the protective film side
In both cases, the laser light is applied to the magneto-optical recording from the transparent substrate side.
Magneto-optical recording that records information by irradiating the film
The method of recording and erasing information
The magnetic field application region applied to the recording film is half of the record carrier.
Has a width of 100 to 200 times the recording track width in the radial direction
The magnetic field is applied by magnetic field applying means,
Perpendicular to the magnetic field at a position 50 μm away from the end face of the adding means
A magneto-optical storage method in which the reduction of the component is 10% or less. 3. A transparent substrate, a magneto-optical recording film on the transparent substrate,
Using a disc-shaped record carrier having a protective film on the magneto-optical recording film
Inverted or intensity modulated according to recorded information
When a magnetic field is applied to the magneto-optical recording film from the protective film side
In both cases, the laser light is applied to the magneto-optical recording from the transparent substrate side.
Magneto-optical recording that records information by irradiating the film
The method of recording and erasing information
The magnetic field application region applied to the recording film is half of the record carrier.
Has a width of 100 to 200 times the recording track width in the radial direction
The record carrier has a dustproof mechanism facing the protective film.
It housed provided with cartridges, optical interchangeable
Magnetic storage method. 4. A transparent substrate, a magneto-optical recording film on the transparent substrate,
Using a disc-shaped record carrier having a protective film on the magneto-optical recording film
Inverted or intensity modulated according to recorded information
When a magnetic field is applied to the magneto-optical recording film from the protective film side
In both cases, the laser light is applied to the magneto-optical recording from the transparent substrate side.
Magneto-optical recording that records information by irradiating the film
The method of recording and erasing information
The magnetic field application region applied to the recording film is half of the record carrier.
Has a width of 100 to 200 times the recording track width in the radial direction
And the above laser light is the same for two semiconductor laser chips.
From the laser array light source stored in the package
Magneto-optical storage method.