JPH0279201A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To record a signal having the high impression efficiency of a magnetic field and about several MHz by constituting a magnetic head with a magnetic core to impress a recording carrier with a magnetic field and a slider to float the magnetic head and providing a non-magnetic conductor on a part of the magnetic core. CONSTITUTION:A floating magnetic head is used as a magnetic head 12, and irradiated with light by an optical head 11 from the substrate side of a recording support 1, the magnetic field is impressed in accordance with the recording information with the magnetic head 12 from a magneto-optical recording film side and recording is executed. A floating type magnetic head is composed of a head core 301 with a wide effective magnetic field impressed area and a slider 302 with a large floating quantity, the magnetic head 12 is constructed to bury a U-shaped magnetic body core 301 into the non-magnetic slider 302 and a non-magnetic conductor 304 is provided on the tip part of the core 301. Consequently, the inductance can be minimized. Thus, a magnetic field inverting time is shortened, a high frequency can be recorded and the impression efficiency of the magnetic field can be improved.

Description

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

[Prior Art] Conventionally, overridable magneto-optical disk devices are disclosed in Japanese Patent Application Laid-open No. 51-107121 and Japanese Patent Application Laid-open No. 59-2150.
As described in No. 08 and Japanese Patent Publication No. 60-48806, there is a method in which the magnetic field applied to the recording film is modulated according to the information to be recorded. The present invention relates to an improvement of a magneto-optical recording device using this magnetic field modulation recording method.

[Problem to be solved by the invention] Conventionally, in an example of overriding using a magnetic field modulation recording method,
An electromagnetic coil for magnetic field generation was installed on the disk, and a modulated magnetic field was applied. The distance between them is 0.1 mm.
It was fixed at about 0.5 mm. In this case, the recording frequency is 0.5 MHz or less, and the problem is that it is not possible to record signals at frequencies of about several MHz.

The purpose of the present invention is to solve the above-mentioned problems, to be able to record signals of several MHz with high magnetic field application efficiency, and to combine the override function, which is an advantage of magnetic disks, and the high density and large capacity, which are advantages of optical disks. The object of the present invention is to provide a magneto-optical recording device that has both of these features.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, an optical head and a magnetic head are opposed to each other by sandwiching a record carrier, and a floating magnetic head is used as the magnetic head, and the substrate side of the record carrier is Recording is performed by irradiating light with an optical head from above and applying a magnetic field whose polarity is reversed or whose intensity is modulated according to the recorded information using a magnetic head from the magneto-optical recording film side.

The floating magnetic head has a wide effective magnetic field application area (0,2
mm x 0.5 mm) Consists of a herad core and a slider with a large flying height (1 μm or more) even at low linear speeds. Further, the magnetic head has a structure in which a U-shaped magnetic core is embedded in a non-magnetic slider, and a non-magnetic conductor is provided at the tip of the core.

[Function] The floating magnetic head used in the present invention has a much wider effective magnetic field application area than conventional magnetic heads.

For example, if it is about 0.2 mm x 0.5 mm, the alignment between the aperture spot and the magnetic head is capacitive, 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 a normal office environment. Moreover, when such a head core with a wide effective magnetic field application area is used, the magnetic field strength hardly attenuates even at a position 10 to 20 μm away from the end face of the head core, so the surface of the magneto-optical recording film has a thickness of about 5 to 10 μm. A protective film can be formed. In addition, 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 coat is extremely high.
Environmental resistance and reliability can be further improved.

In the magnetic head of the present invention, since only the head core portion is made of a magnetic material, it is possible to reduce inductance. This shortens the magnetic field reversal time and enables high frequency recording. Moreover, by making the helad core part U-shaped and further installing a non-magnetic conductor at the tip of the core, the efficiency of applying the magnetic field can be improved. Furthermore, by making a portion of the slider from a non-magnetic material, it is possible to prevent the effective magnetic field strength applied to the magneto-optical recording film from decreasing due to the magnetic field leaking from the diaphragm lens actuator or the like.

Information is recorded by irradiating the magneto-optical recording film with high-power laser light from the substrate side using an optical head, and at the same time, from the magneto-optical recording film side, a modulated magnetic field whose polarity is reversed or whose intensity is modulated according to the recorded information is sent by a magnetic head. This is done by applying a voltage. This allows new signals to be overwritten while erasing old signals. In other words, it is possible to realize a magneto-optical recording 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] An example of the present invention will be described below with reference to FIG. In the figure, reference numeral 1 denotes a magneto-optical disk which is a rotating recording carrier, and has a magneto-optical recording film 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, passes through a beam splitter 4, and is focused by a lens 5, which enters a focusing lens 5. The light beam is focused on a disk substrate 103. The light enters the disk from the side and forms a fine pair of spots with a diameter of about μm on the recording film 101. The aperture lens 5 follows the vertical vibration of the disk 1 so that the focus is always on the recording film, and it also follows the eccentricity of the information recording track on the disk so that the light spot is always on the desired track. is attached to the actuator 6. The reflected light from the disk 1 passes through the aperture lens 5, is reflected by the beam splinter 4, and is sent 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 optical 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 the λ/2 plate 8o.
, passes through lens 802, and polarizes beam splitter 303.
The light is separated into each polarization component of s'p by the photodetector 80.
4 and 805, respectively. The signals converted into electrical signals by both photodetectors are differentiated by a differential amplifier 10 and obtained as a magneto-optical signal.

The magnetic head 12 is disposed on the recording film side, facing the optical head 11 with the disk sandwiched therebetween. In FIG. 1, for explanation purposes, the magnetic head is rotated 90'' within the disk surface from its actual arrangement and is shown enlarged as a bird's-eye view.The magnetic head 12 applies a magnetic field to the recording film as described later. It consists of a coil part that floats the whole head, and a part of a slider that floats the entire head.During the disk rotation, the head is floated by the air pressure generated by the rotation of the disk.The flying height is 1 μm or more (preferably 2 μm or more).With this level of flying 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.
act 5 tart 5 top) method or a method in which the magnetic head is kept away from the disk until the disk rotation becomes constant may be used. However, when replacing the disk 1, a mechanism 16 for moving the magnetic head 12 up and down is required regardless of which of the above two methods is used.

The magnetic head 12 further includes an optical head 11 and a support arm 1.
5, the magnetic head is integrally connected with the optical head so as to be able to operate in conjunction with the optical head, and the distance between the magnetic head and the magnetic head is kept 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 figure, but if they are not integrated, a means for keeping the distance between them constant and a magnetic head directly above the optical spot are provided when moving the recording in the radial direction of the disk. A magnetic head moving means is required to install the magnetic head.

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 of recording information. To record information, the semiconductor laser 2 is caused to emit light continuously at high output as shown in FIG. is heated above its Curie temperature to reduce the coercive force of the area irradiated with light. At this time, the magnetic head 12 is driven by the magnetic head drive circuit 14, and a modulated magnetic field (FIG. 2(C)) whose polarity is reversed according to the recorded information (FIG. 2(a)) is applied to the magneto-optical recording film 101. Apply voltage and record information. The recording state is shown in FIG. 2(d). 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 direct current Add bias component. According to this method, even if new information is recorded in a portion where information is already recorded, the old recorded information will not remain, and the old information can be erased by overwriting, that is, by overwriting the information.

Here, the magnetic head, which is the main component of the present invention, will be explained 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. From the perspective of preventing head crashes caused by dust, etc., the flying height should be 1 μm or more (preferably 2 μm or more), and from the perspective of alignment between the optical spot and the magnetic head, the effective magnetic field application area of the head core should be 0.1 mm x 0.1 mm or more, 1 mm.
X 1 mm or less, preferably 0, 1 mm
0.0 mm or more and 0.2 mm x 0.5 mm or less.

FIG. 3 shows the structure of a floating magnetic head according to the present invention. FIG. 3(a) is a goose bump diagram of the magnetic head, and FIG. 3(b) is a developed diagram thereof. The magnetic core 3°1 is, for example, M n −
It is made of magnetic material such as Zn and has a rectangular shape. Furthermore, this magnetic core 301 is embedded in a slider 302 made of a non-magnetic material such as ceramic. In conventional magnetic heads used for magnetic disks and the like, a magnetic core and a slider are integrally fabricated, and a portion of the slider is also made of a magnetic material. If this magnetic head is used as is in a magneto-optical disk, for example, the magnetic field leaking from the aperture lens actuator will concentrate on a part of the slider, so depending on the polarity of the magnetic field generated from the magnetic core, both magnetic fields will work in a direction that cancels each other out, causing recording. The effective magnetic field strength applied to the film is reduced.

If the slider 302 is made of a non-magnetic material, the above phenomenon will not occur and the magnetic field generated from the magnetic core 301 can be efficiently applied to the recording film. Furthermore, since it is possible to create a structure with less polarity than when the entire magnetic head is made of magnetic material, the inductance of the magnetic head can be lowered, making it possible to record higher frequencies. .

The magnetic head 12 is set so that one end 301a of the U-shaped magnetic core is directly above the narrowing spot 501. Since the magnetic lines of force have a distribution as shown in the figure, a magnetic field in the opposite direction to 301a is generated directly below one end 301b of the U-shaped magnetic core.

By utilizing this, by arranging narrowed-down spots just below both ends 301a and 301b of the U-shaped magnetic core, one can be used as a recording spot and the other as an erasing spot, allowing override using two optical spots. You can also do it.

The winding 303 of the magnetic core is wound around the U-shaped magnetic core located directly above the narrowing spot. Thereby, the strength of the magnetic field generated at the end surface 301a can be increased, and the efficiency of magnetic field generation can be increased.

The closer the winding 303 is located to the slider sliding surface, the higher the magnetic field generation efficiency and the lower the inductance of the magnetic head. From this point, slider 302
The length of the part that supports the magnetic core 303 (d in the figure)
If the mechanical strength of the magnetic core is not sufficient from the viewpoint of mechanical strength, a structure that supports both the upper and lower sides of the U-shaped magnetic core is adopted as shown in FIG.

Next, the core portion of the magnetic head used in the present invention will be explained in more detail. As shown in FIG. 3, a non-magnetic conductor 304 is placed around the open end of the magnetic core 301, which is formed into a substantial U-shape with an open end, located directly above the narrowing spot. installed. Figure 5 (a
), in addition to the magnetic field applied perpendicularly to the recording film at the open end of the core, there is a so-called leakage magnetic field that is not directly applied to the recording film because it is directed from the bottom of the winding toward the other open end of the core. occurs. As this increases.

The magnetic field generation efficiency of the core (the ratio of the generated magnetic field strength to the flowing current) decreases, and the power consumption of the magnetic head increases. Therefore, a specific magnetic conductor 304 is installed at the open end portion of the core, as shown in FIG. 3(b). When the magnetic field generated from the core is reversed in polarity or modulated in intensity at a high frequency, eddy currents are generated in the specific magnetic conductor 304, resulting in a magnetic shielding effect. This eliminates the above-mentioned leakage magnetic field, and the magnetic field generated from the core is concentrated on the surface of the open end of the core that faces the recording film. Therefore, the efficiency of magnetic field generation can be increased. However, in FIG. 5, for simplicity, only the core portion is shown and a portion of the slider is omitted.

Examples of non-magnetic conductors include Ag, Al, Au,
Any one of Cr, Cu, Ta, Ti, or an alloy of two or more selected from these is used.

The thickness of the non-magnetic conductor is preferably greater than the so-called skin depth, which is determined from the recording frequency, the conductivity of the non-magnetic conductor, and its magnetic permeability.

As for the installation state of the non-magnetic conductor, there are various possible installation states as shown in FIG. 6 in addition to those shown in FIGS. 3 to 5. Basically, it is preferable that they be placed around the entire circumference of the core, but depending on conditions such as the processing method, they may be placed in a part of the core. However, the 6th
In the figure, for simplicity, only the core portion is shown and a portion of the slider is omitted.

The effect of installing a non-magnetic conductor is, for example, when the configuration shown in Fig. 5 is adopted, the core tip size is 100 μm x
If the non-magnetic conductor is Cu, the height (distance from the surface facing the recording film to the winding) is 200 μm, and the thickness is 200 μm, the generated magnetic field strength will be approximately 5 MHz for a recording frequency of 5 MHz. Can be increased by 2 times. Furthermore, it has the effect of reducing the inductance of the magnetic head by about 10 to 20%. This allows high-speed magnetic field reversal or intensity modulation, and thus enables high-speed magnetic field modulation override.

The above-mentioned effects can be further enhanced by using a core shape with a narrowed tip portion as shown in FIGS. 6(c) and 6(c). Note that the end area of the open end portions other than the open end portion that applies the magnetic field to the recording film does not necessarily have to be made small. Also,
Means for reducing the end area of the open end include reducing the width of the core, reducing the thickness of the core, or using both of the above (forming into a pyramidal or conical shape).
etc. are possible. Furthermore, although the shape of the core has been shown as an example of a U-shape or a U-shape, it is not necessarily limited to this.
It may be formed into a substantial U-shape that has a pair of open ends facing the recording film and forms a closed magnetic path.

Here, the influence on the generated magnetic field strength, inductance, etc. when the core shape of the magnetic head 12 in the present invention is changed will be described quantitatively.

First, FIG. 7 is a diagram showing the relationship between the dimension B between the open ends of the core 301, magnetic field strength, and inductance. The radicals of the core 301 used are as shown schematically in FIG. 7, and the core 301 was formed to have a thickness of 0.2 mm.

The winding 303 is formed by winding a conductive wire with a wire diameter of 0.035 mm 30 times. As is clear from the figure, when the dimension B between the open ends is increased, the straight line I! a and curved uAb reduce both magnetic field strength and inductance.

Since the magneto-optical recording magnetic head is used at a high frequency of 5 MHz or higher, it is desirable that the inductance is as small as possible. Therefore, the dimension B between the open ends of the core 301 is
It is advantageous to have a large value.

However, increasing the dimension B is disadvantageous because the magnetic field strength decreases as indicated by Ma. On the other hand, if the above-mentioned dimension B is decreased, the magnetic field strength increases, but as shown in the curve, the inductance also increases, and the magnetic flux is short-circuited between the open ends of the core 301, resulting in an effective This is disadvantageous because it reduces magnetic flux. Therefore, the dimension between the open ends of the core 301 should be set between 0.4 and 0.4.
It is preferable to set it to 8 mm.

FIG. 8 shows the distance W between the open end of the core 301 and the winding 303.
FIG. 3 is a diagram showing the relationship between magnetic field strength, magnetic field strength, and inductance. The dimension between the open ends of the core 301 used was 0.6 m.
It is the same as that shown in FIG. 7 above, except that it is set to m.

As is clear from FIG. 8, the magnetic field strength shown by curve a does not change significantly even if the distance W between the open end of the core 301 and the winding 303 changes. On the other hand, the inductance increases in proportion to the distance W, as shown by the straight line.

Therefore, it is preferable to set the interval W as small as possible.

FIG. 9 is a diagram showing the relationship between the width T of the open end of the core 301 and the magnetic field strength. The core 301 and winding 303 used were the same as those shown in FIGS. 7 and 8, but two types were used, with the width A in the cross section of the core 301 being 0.2 mm and 0°4 mm, respectively. . As is clear from the figure, the smaller the width T, the greater the magnetic field strength, and the end area of the open end of the core 301 is
It is recognized that it is preferable to form the cross-sectional area smaller than the other portions of 01 in order to increase the magnetic field strength. In this case, it is preferable to form the open end of the core 301 into a pyramidal shape, since this is effective for increasing the magnetic flux density at the end face, prevents leakage magnetic flux from occurring, and increases the magnetic flux used by the recording medium. . Note that the end area of the open ends other than the open end where a magnetic field is applied to the recording medium does not necessarily have to be reduced. Further, as a means for reducing the end area of the open end portion, other than forming the width dimension small.

The thickness may be made small, or both may be used in combination.

Now, FIG. 10 shows a non-magnetic conductor 30 at the open end of the core 301.
A comparison is made between cases where 4 is installed and cases where 4 is not installed. For ease of comparison, the generated magnetic field strength is shown as the value at the magnetomotive field IAT (ampere-turn) at a position 20 μm from the core end face, and the inductance is shown as the value per turn of the winding in arbitrary units. It is. Cu was assumed to be the non-magnetic conductor to be installed. The core dimensions are as shown in the figure. The strength of the generated magnetic field is w' = o.

It has a peak at 2mm. From this, W' is 0゜lm
It is preferable to set m to about 0.4 mm. Although inductance tends to increase as W' increases, providing a nonmagnetic conductor also has the effect of suppressing the increase in inductance.

The above describes the case of a single metal or alloy as a non-magnetic conductor, but these metals or alloys can be made into powder or particles and mixed into glass or resin, etc., at the position of the above example. A similar effect is expected even if installed.

In the above description, the slider has a so-called two-rail structure, but the present invention is also applicable to sliders of other structures. Regarding the position of embedding the magnetic core, in this example, it is placed on one rail near the air outflow end, but it can also be placed in the center of two rails or in the center of the outflow and inflow ends. It goes without saying that the present invention is applicable to any location.

[Effects of the Invention] As explained above, according to the present invention, in a magneto-optical disk device using a magnetic field modulation recording method using a floating magnetic head, it is possible to improve the magnetic field generation efficiency of the magnetic head and reduce the inductance of the coil. This enables high-speed magnetic field modulation recording with low power.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of the device according to the present invention, and FIG.
The figure shows the recording principle of the magnetic field modulation recording method, FIG. 3 shows an embodiment of the floating magnetic head of the present invention, and FIG. 4 shows another embodiment of the floating magnetic head of the present invention. 5 shows the effect of a non-magnetic conductor, FIG. 6 shows another example of the magnetic core, and FIGS. 7, 8, 9 and 10 show the effects of the present invention. It is a figure showing an effect. Explanation of symbols 1...Disk, 2...Semiconductor laser, 3...Collimating lens, 4...Beam splitter, 5...
Aperture lens, 8... Magneto-optical signal detection system, 9...
Light point control haiku detection system, 11... optical head, 12...
Magnetic head, 301... Core, 302... Slider, 303... Winding wire, 304... Nonmagnetic conductor. 7: Pyrotechnics 4 Qi Sith 7 yoy: 94 members i Masteng 7ri λ: Cheng Xi number 7 ρ 3: Te 耘 7 crawl 1 ζ 2nd C 匈 R sacrilege 1 Shuso CC) Q Ufill Saki board 7 ρ 3 / ,? ri μ no ρ2 (C) c~ 8 (Mu-fPL) W (4rLfPL) 7th o port

Claims (1)

[Claims] 1. A magnetic field whose polarity is inverted or whose intensity is modulated according to recorded information is applied to the magneto-optical recording film on the record carrier by a floating magnetic head, and the floating magnetic head A magneto-optical recording device that records information by continuously irradiating high-power laser light from an optical head facing a magnetic head, the magnetic head comprising a magnetic core that applies a magnetic field to the record carrier, and a magnetic core that applies a magnetic field to the recording carrier. A magneto-optical recording device comprising a slider for floating the magnetic head, and a part of the magnetic core is coated with a non-magnetic conductor. 2. The magnetic core is formed into a substantial U-shape with an open end, and the open end of the magnetic core is provided so as to face a record carrier made of a perpendicular magnetic film having a magneto-optic effect. 2. The magneto-optical recording device according to claim 1, wherein the magnetic field from one of the open ends of the recording film acts on the recording carrier in a direction perpendicular to the film surface of the recording film. 3. The magneto-optical recording device according to claim 2, wherein the magnetic conductor is arranged around at least one of the open ends of the magnetic core. 4. The magneto-optical recording device according to claim 2, wherein the non-magnetic conductor is embedded between open ends of the magnetic core. 5. The above non-magnetic conductor Ag, Al, Au, Cr, Cu,
5. The magneto-optical recording device according to claim 1, wherein the magneto-optical recording device is made of Ta, Ti, and alloys thereof. 6. A magneto-optical recording device according to claims 1 and 2, characterized in that the open end of the magnetic core is provided with resin or glass mixed with a granular or powdery non-magnetic conductor. 7. The nonmagnetic conductor is Ag, Al, Au, Cr, C
7. The magneto-optical recording device according to claim 6, characterized in that it is made of u, Ta, Ti, and alloys thereof.