JPS63217548A - Magneto-optical storage device - Google Patents

Abstract

PURPOSE:To widen the effective magnetic field impressing area of a magnetic head and to improve the performance of an optical disk by disposing an optical head and the magnetic head face to face sandwiching a recording carrier, and using a floating type magnetic head for the said magnetic head. CONSTITUTION:On top of the transparent disk substrate 103 of a magnetic disk 1 as a rotary recording carrier,a magneto-optical recording film 101 having magnetooptics effect and a protection film 102 are formed. A light beam from the semiconductor laser 2 of the optical head 11 is subjected to a beam splitter 4 and is made incident to a condensing lens 5, and thus condnesed beam is radiated on the disk 1. Sandwiching this disk 1, the magnetic head 12 is so disposed in facing the optical head 11. And this head 12 is constituted of a coil to impress a magnetic field on the recording film 101 and a slider part to float the entire head. The hight of the floating of the head 12 is made more than 1mum, and the extent of the magnetic field impressing area in which the head 12 is effective in recording/erasing is limited within a range 0.01mm<2>-1mm<2>, so that said magnetic impressing area expands in the direction orthogonal to the track direction rather than the track direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical storage device, and particularly to a magneto-optical disk device that can be overridden (overwritten) using a magnetic field modulation method.

[Prior Art] Conventionally, as an overridable magneto-optical disk device, IEE
nMagnetics MAG-20, Volume
e 5p, 1o13 (1984), or the method using two light spots as described in
Examples include a method of modulating the printing magnetic field on the recording film according to the information to be recorded, as described in Japanese Patent Application Publication No. 1-107121, Japanese Patent Application Laid-Open No. 59-215008, and Japanese Patent Publication No. 60-48806. The present invention particularly relates to a magneto-optical storage device using the latter magnetic field modulation method.

[Problem that the invention seeks to solve]

Conventionally, in an example of overriding using a magnetic field modulation method, an electromagnetic coil for generating a magnetic field is installed on the disk, and a modulated magnetic field is applied. The distance between the two is 0.1 mm to 0.5+
It was fixed at about ms. In this case, the recording frequency is 0
．． There was a problem in that it was not possible to record signals at a frequency of about 5 MHz or less, and several MHz.

The purpose of the present invention is to solve the above-mentioned problems and to create an optical disc that can record signals of about 5-odd MHz and has both the override function, which is an advantage of magnetic disks, and the high density and large capacity, which are advantages of optical disks. An object of the present invention is to provide a magnetic storage device.

[Means for solving problems]

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 recording carrier in between, and a floating magnetic head is used as the magnetic head. This floating magnetic head has a wide effective magnetic field application area (
It consists of a rad core (approximately 0.2 mm x 0.5 m+s) and a slider that has a large flying height (more than 1 meter Lm) even at low linear speeds. Then, light is irradiated from the substrate side of the record carrier by an optical head, and a magnetic field is applied by a magnetic head from the magneto-optical recording film side. 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, with a thickness of, for example, 1 to 20 μm.

[Effect]

The floating magnetic head used in the present invention has a much wider effective magnetic field application area than conventional magnetic heads.
If the value is about 2■■X0.5+a+i, it is easy to align the aperture spot and the magnetic head, and it is stable against temperature changes and vibrations. Further, if the flying height is 1 μm or more, so-called head crashes due to dust or the like hardly occur, and the device can be used in the atmosphere. Furthermore, when using a head core with a wide effective magnetic field application area as described above, from the end face of the head core, 10
Since the magnetic field strength hardly attenuates even at positions separated by ~20 μm, a protective film as thick as about 5 to 10 μm can be formed on the surface of the magneto-optical recording film. Moreover, unlike conventional coated magnetic disks, etc., the protective film can be coated purely for protection without containing magnetic powder, so the durability of the protective coating is extremely high, ensuring environmental resistance and reliability. This can be further improved.

To record information, an optical head irradiates the magneto-optical recording film with high-power laser light from the substrate side, and at the same time a magnetic head applies a modulated magnetic field whose polarity is reversed according to the recorded information from the magneto-optical recording film side. Let's do it by doing this. This allows new signals to be overwritten while erasing old signals. Recording density is determined by the size of the light spot. In other words, it is possible to realize a magneto-optical storage device that has both the high density and large capacity of an optical disk and the override function of a magnetic disk, without substantially impairing the non-contact characteristic of optical recording.

〔Example〕

A first embodiment of the present invention will be explained with reference to FIG.

In the figure, l indicates a magneto-optical disk j which is a rotating recording carrier, and has a magneto-optical recording medium 101 having a magneto-optic effect and a protective film 102 on a disk-shaped transparent substrate 103. For example, light emitted from a light source consisting of a semiconductor laser 2 is converted into a parallel beam by a collimating lens 3,
The beam enters the aperture lens 5 via the beam splitter 4.

The light beam narrowed down by the lens 5 is directed to the disk substrate 1.
It enters the disk from the 03 side and appears on the recording film 101 with a diameter of about 1
Forms micro spots of μm. The focusing lens 5 follows the vertical vibration of the disk 1 so that the focus is always on the recording film, and also follows the eccentricity of the information recording track on the disk so that the spot is always on the desired track. It is attached to the actuator 6 like this. The reflected light from the disk 1 passes through the aperture lens 5, is reflected by the beam splitter 4, and is transmitted by the beam splitter to the magneto-optical signal detection optical system 8 and the light spot control signal detection optical system 9, which detects defocus and track deviation. be guided.

An example of the magneto-optical signal detection system 8 is shown in the figure. This is a differential signal detection method using a λ/2 plate 801 and a polarizing beam splitter 803. The light incident on the magneto-optical signal detection optical system 8 passes through a λ/2 plate 801 and a lens 802, is separated into s'p polarization components by a polarizing beam splitter 803, and is focused on photodetectors 804 and 805, respectively. The signals converted into electrical signals by the two photodetectors are differentially differentiated by the differential amplifier 10 and obtained as magneto-optical signals.

The magnetic head 12 is placed on the recording film side, facing the optical head 11 with the disk 1 in between. For explanation purposes in Figure 1, *The head is 90'' in the disk surface from the actual arrangement.
It is rotated and enlarged as a bird's-eye view. As will be described later, the magnetic head I2 is composed of a coil part that applies a magnetic field to the recording film and a slider part that makes the entire head levitate. During the disk rotation, the magnetic head I2 is made levitated by the air pressure generated by the disk rotation. The flying height is 1 μm or more (preferably 2 μm)
above). If this is the amount of floating height.

Head crashes caused by dust, etc., which are a problem with magnetic disks, do not occur, and the device can be used in the atmosphere and media can be exchanged.

The magnetic head 12 is also moved from 5 to Lo by a support spring 13.
It is pressed against the disk 1 with a load of about .g. When the disk starts and stops rotating, the magnetic head is kept in contact with the disk using the so-called CSS (contact, 5tart, 5top) method, or the magnetic head is removed from the disk until the disk rotation speed reaches a constant value. It doesn't matter which method is used; however, when replacing the disk 1, regardless of which of the above two methods is used, the moving mechanism 1 that moves the magnetic head 12 up and down
6 is required.

The magnetic head I2 further includes an optical head 11 and a support arm ■
5, and is configured to be able to operate in conjunction with the optical head, so that the distance between them is constant and at the same time the magnetic head is always placed directly above the optical spot on the disk.

It is not necessarily necessary to integrate the two as shown in the diagram, but
If the recording position is not integrally coupled and the recording position is moved in the radial direction of the disk, means for keeping the distance between the two constant and magnetic head moving means for placing the magnetic head directly above the optical spot are required.

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

FIG. 2 shows a method for recording information. To record information, the semiconductor laser 2 is caused to emit light continuously at high output as shown in FIG.
The temperature of the magnet is heated to near one Curie temperature, and the coercive force of the area irradiated with light is reduced. At this time, the magnetic head 12 is driven by the magnetic head drive circuit 14, and the recorded information (FIG. 2(a)
)) The modulated magnetic field whose polarity is reversed according to (Fig. 2 (C))
is applied to the magneto-optical recording film 101 to record information.

The recording state is shown in FIG. 2(d). In addition, if it is necessary to change the applied magnetic field strength in order to keep the recording conditions constant regardless of changes in the inner or outer circumference of the disk or in the laser output, in addition to polarity reversal, intensity modulation or a direct current bias component to the magnetic field can be applied. Add. According to this method, even if new information is recorded in an area where information is already recorded, the old recorded information will not remain, and it is possible to erase the old information by overwriting, that is, by overwriting the information. Become.

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

The magnetic head 12 has a large flying height even when the linear velocity is low.
In addition, a floating magnetic head with a wide effective magnetic field application area is used. The flying height is 1 μm or more (preferably 2 μm or more) to prevent head crashes caused by dust, etc., and the effective magnetic field application area of the head core is 0.1 m+iX0.1 m+m1+e from the viewpoint of alignment between the optical spot and the magnetic head
wX1mm or less, preferably 0.1m+iX0.1+a
+11 or more and 0.2+@mX0.5+u+ or less.

FIG. 3 shows an example of a magnetic head used in the present invention. FIG. 3(c) is a diagram showing the slider sliding surface. The entire surface facing the disk is a sliding surface, and two substantially circular through holes are provided on the central axis AA' of the slider 301 along the disk advancing direction. As a result, compared to the conventional magnetic head shown in FIG. 4, it is possible to increase the sliding surface area that contributes to the flying height, thereby increasing the flying height. Also, since the air pressure distribution for levitation is as shown on the side of the same figure (c), the slider is
Since it is supported at four points, stable levitation can be achieved against pitching or rolling. The through hole may be a substantially circular recess, and in this case, the depth of the recess is set so as to obtain the air pressure distribution shown in FIG. 3. If you use this slider, for example, if the external dimensions of the sliding surface are 3 mm x 4 mie, the hole diameter is 0.6 ms, and the load is 5 g,
As shown in FIG. 5, a flying height of 2 μm can be obtained even when the disk peripheral speed is about 3 m/sec. In the above example, there were two circular openings or two through holes, but as shown in Fig. 6, there may be one, and the shape of the recess or six does not have to be exclusively oval or rectangular. It doesn't have to be circular either.

A magnetic field to the recording film is applied by a coil 302 provided at the tip of the air outflow end. The coil magnetic core is, for example, Mn-Z
It is made of a magnetic material such as n-ferrite, and may be integrally processed with the slider, or may be formed into a form in which only the FA core and coil portion are processed separately and then combined with the slider. Particularly in the latter case, the slider need not be made of a magnetic material such as Mn--Zn ferrite, but may be made of a non-magnetic material such as ceramic.

If a magnetic material is used as the slider material, the leakage magnetic field of the actuator 6 will be concentrated on the slider side, and the net magnetic field strength applied to the recording film may be reduced, or the magnetic field generated in the magnetic core portion 302 and the leakage magnetic field may interact. This action may cause vibrations of the magnetic head, but using a non-magnetic slider has the effect of preventing the above phenomenon.

Further, the position at which the magnetic field is applied does not necessarily have to be at the outflow end, but may be placed inside the slider as shown in FIG. Furthermore, in this case, a non-magnetic ceramic or the like is used as the slider 301, and the coil magnetic core 302
It is also effective to use only a magnetic material or to use an air-core coil. When an air-core coil is used, the inductance of the magnetic head as a whole can be reduced, which has the effect of improving the frequency response of the magnetic head, as will be described later.

The area of the effective magnetic field application area at the tip of the coil is determined by (i) alignment accuracy of the magnetic head, (ij,) amount of disk eccentricity, (jii) frequency response of the magnetic head, etc. A larger area is required than in (i) and (ii), but since the inductance increases, (iii)
) frequency response deteriorates. For example, 0.2 in the circumferential direction
s + mX radial direction 0, 5 ■ to 0.1 + * + * XO
, about 1 mm is preferable. The former can correspond to a recording frequency of about 3 to 5 MHz, and the latter can correspond to a recording frequency of about 5 to 10 MHz.

In the former example, the area is wider in the radial direction than in the circumferential direction of the disk. This is to prevent the optical spot from deviating from the effective magnetic field application area even if the optical spot moves in the radial direction due to disk eccentricity. As shown in FIG. 1, the magnetic head 12 is fixed to the optical head 11 by a support arm 15 and moves in the radial direction of the disk in conjunction with the optical head. If the magnetic head 12 is also provided with a mechanism that follows the disk eccentricity, it is possible to reduce the area to which the magnetic field is applied, but in this case, a position control mechanism for the magnetic head is required separately from the optical head. , the equipment becomes complicated and expensive.

Therefore, in this embodiment, in order to make the device configuration simple and inexpensive, an effective magnetic field application area is provided that is wider in the radial direction than in the circumferential direction of the disk. Furthermore, when the optical head is moved discontinuously using, for example, a step motor, the amount of radial movement of the focused spot becomes greater than the disk eccentricity, so it is necessary to make the radial direction wider than the disk eccentricity. In magnetic disks and floppy disks, the area to which the magnetic field is applied by the magnetic head corresponds to the recording track width, but in the case of the magnetic head used in the magneto-optical disk like this example, for the reasons mentioned above, the area to which the magnetic field is applied corresponds to the width of the recording track. It has a width of 100 to 200 wheels, which is the width of the record track.

The magnetic field application area as described above is 50 to 100 times wider than that of a magnetic head for a magnetic disk. Therefore, the rate of decrease in the perpendicular component of the magnetic field with respect to the distance from the head is much smaller than that of a magnetic disk head.1For example, 0
．． In the case of a magnetic head with a magnetic field application area of 5m + m x 0.2mm, as shown in Figure 8, the distance from the end surface of the head is 20μ.
Even at positions separated by m, the decrease in the vertical component of the magnetic field is 2 to 3%.
That's about it.

If the magnetic field application area is wide, several tens of
Although the decrease in the magnetic field strength at the μm position can be made smaller than in the example shown in the figure, the single frequency characteristics deteriorate.

In order to realize a recording frequency of several MHz, the magnetic field application area is preferably about 0.5 mm x 0.21 mm or less, and the distance between the magneto-optical recording film and the magnetic head is preferably 30 μm or less. The above points are important in determining a disk structure that takes sliding resistance into consideration. Further, even if the magnetic field strength fluctuates by about 1 μm due to the vertical movement of the magnetic head 12, it does not pose a problem as in the case of a magnetic disk.

FIG. 9 shows an example of the configuration of a disk used in the present invention. The disk is for single-sided recording, and a substrate 901 is irradiated with light from the substrate 901 side and a magnetic field is applied from the recording film 903 side.
uses glass or plastic with a thickness of approximately 1.2+i+s. A magneto-optical recording film layer (for example, TbFeC) with a thickness of about 1000 mm.

On the substrate side, an enhancement film (for example, Si3
N4. (SiO, etc.) 902, and the other side has a corrosion-resistant
A protective film (approximately 2000λ, eg, Si3N4.SiO, etc.) 904 is provided to improve oxidation resistance and the like. On top of that, a protective coat 905 with a thickness of about 1 to 20 μm, preferably 5 to 10 μm, is applied to improve the sliding resistance with the magnetic head.
form a degree. At this time, the recording film 903 and the magnetic head 12
The distance between them is about 10 to 20 μm, but as shown in FIG. 8, unlike a magnetic disk, the magnetic field strength does not decrease at this distance.

As the translation coat 905, for example, an ultraviolet curing resin is used. It is also possible to mix a so-called filler or lubricant, such as AQ203, into the ultraviolet curable resin. For example, when we conducted a spherical sliding test using a UV-curable resin mixed with a filler, we were able to achieve over 1 million sliding cycles. In the case of magneto-optical disks, if the damage does not reach the recording film, it will not affect the recording, playback, and erasing characteristics. Therefore, as mentioned above, the thickness of the protection coat can be made thicker, which will improve the disk life and environmental resistance. can improve the reliability of the device.

Furthermore, the disk 1 is replaceable, as shown in FIG. 10(a).
It is housed in a cartridge 906 like this. Inside the cartridge 906, a dustproof mechanism 907 made of, for example, linen paper is provided opposite to the protective coat of the disc in order to remove dust attached to the protective coat.

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 shown in FIG. Support arm 15. The magnetic head moving device 16 is omitted for simplicity. In addition, in FIG. 1(a), the positional relationship of the narrowed-down spots on the disk is shown rotated by 90'' within the disk surface for explanation as in FIG. 1.As shown in FIG. The light source is a semiconductor laser array in which two different laser chips LDI and LD2 are mounted in one package with their active layers facing each other.LDl has a wavelength of 780 nm.
This is a low-power, low-noise laser used for magneto-optical signal regeneration and optical spot control. On the other hand, LD2 is a high output laser with a wavelength of 830 nm, and is used for recording and erasing signals. Optical spot SPI formed by both laser light sources on the disk (wavelength 780 nm)
and SF3 (wavelength 830 nm) are on the same track as shown in the same figure (C), and the spot SP
2 in advance. This allows error checking to be performed at spot SP1 at the same time as recording is performed at spot SP2. Error checking is performed by comparing the recorded signal and the magneto-optical signal reproduced by the spot SP2 using a comparator 17.The comparison result is input to the controller 18, and the result of the comparison is inputted to the controller 18, and it is determined that there is a mismatch between the two signals, that is, an error has occurred. In this embodiment, the signal before input to the magnetic head drive circuit 14 is used as the original recording signal to be compared. A head drive current may also be used.

Conventionally, in order to rewrite the recorded information on a magneto-optical disk, one rotation of the disk was required for erasing, recording, and checking in the order of 9, totaling 3 rotations, but according to this embodiment,
Since the above three operations can be performed in one rotation, the effective data recording time can be significantly shortened.

〔Effect of the invention〕

As explained above, the present invention combines the high density and large capacity of an optical disk with the high speed and override function of a magnetic disk without significantly impairing the non-contact recording, playback, and erasing features of optical recording. This makes it possible to realize a magneto-optical storage device, which has an extremely large effect on improving the performance of optical disks.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIG. 2 is a diagram showing the information recording operation in the present invention, and FIG. 3 is a diagram showing an example of the structure of the magnetic head used in the present invention. FIG. 4 is a diagram showing the structure of a conventional magnetic head. FIG. 5 is a diagram showing an example of the flying characteristics of the floating magnetic head used in the present invention, FIGS. 6 and 7 are diagrams showing other examples of the magnetic head used in the present invention, and FIG. A diagram showing an example of the magnetic field intensity distribution generated by the magnetic head used, FIG. 9 is a cross-sectional view showing an example of the structure of the magneto-optical disk used in the present invention,
FIG. 10 is a diagram showing an example of the structure of a disk cartridge, and FIG. 11 is a block diagram showing a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Disk, 2... Semiconductor laser, 5... Aperture lens, 8... Magneto-optical signal detection optical system, 9...
- Light spot control signal detection optical system, 11... Optical head, 12
...Magnetic head, 301...Slider, 302...
- Coil, 901... Disk substrate, 903... Magneto-optical recording film, 905... Protective coat, 14... Wavelength separation filter, LDI... Laser chip for signal reproduction,
LD2... Laser chip for signal recording. 1st Figure 1 Kizuki Todoro 9 Brass Matafututa/ : ; Li 4 Figure 3 o / Open! Figure? Disph line lv C Ki no '5ec) 2nd 7th λl 2nd △・l White Rime IE Kattsu (p duck) Dirt 9 Buno 2 Stone L?, Hey,,,y Ta ρ3 Pus niri L Kiko 7 books 1 Shikwo ρノ 7 Toto 沫) Scarcity ρ4 ノIJ committee November' luster. 2 Enhancement nL par at it coat? 6 no θ b stone

Claims (1)

[Claims] 1. A magnetic field whose polarity is reversed or whose intensity is modulated according to the recorded information is applied by the magnetic field applying means to the magneto-optical recording film on the record carrier, and a high-output laser beam is continuously emitted from the optical head. In a magneto-optical storage device that records information by irradiation, a floating magnetic head opposed to the optical head with the record carrier in between is used as the magnetic field applying means, and the light irradiates from the substrate side of the record carrier. , a magneto-optical storage device characterized in that a magnetic field is applied from the recording film side. 2. The magneto-optical storage device according to claim 1, wherein the floating magnetic head has a flying height of 1 μm or more. 3. The floating magnetic head has a magnetic field application area of 0.1 mm x 0.1 mm or more, which is effective for recording and erasing.
3. The magneto-optical storage device according to claim 1, wherein the size is 1 mm x 1 mm or less. 4. The magneto-optical storage device according to claim 1, wherein in the floating magnetic head, the effective magnetic field application area is wider in the direction perpendicular to the track direction than in the track direction. 5. The recording frequency of the floating magnetic head is 2MH_
Claim 1, characterized in that it is greater than or equal to z;
The magneto-optical storage device according to item 2, 3, or 4. 6. Claims characterized in that the floating magnetic head has a slider provided with at least one substantially circular recess or through hole on the central axis along the traveling direction of the record carrier. The magneto-optical storage device according to item 1, 2, 3, 4, or 5. 7. Claim 1, wherein the floating magnetic head has a slider made of a non-magnetic material.
The magneto-optical storage device according to item 2, 3, 4, 5, or 6. 8. Claims 1 to 7, characterized in that the record carrier has the magneto-optical recording film on only one side, and a protective film of 1 μm or more and 20 μm or less is formed on the recording film. 2. The magneto-optical storage device according to any one of the items. 9. The magneto-optical storage device according to claim 8, wherein the record carrier is housed in a cartridge provided with a dustproof mechanism facing the protective film and is replaceable. 10. Claims 1 to 9, wherein the optical head has a laser array light source in which two semiconductor laser chips with different wavelengths, outputs, and noise characteristics are housed in the same package. 3. The magneto-optical storage device according to any one of paragraphs.