JP2522585B2 - Magneto-optical memory device and manufacturing method thereof - Google Patents

Description

The present invention relates to a magneto-optical memory element for a magneto-optical recording / reproducing apparatus having a floating magnetic head and a method for manufacturing the same.

[Conventional technology]

In recent years, in place of a read-only optical memory element such as a so-called compact disc, a magneto-optical memory element, which is a large-capacity memory capable of recording / reproducing and erasing information, has been actively researched and developed, and has reached a stage of practical application. . Recently, a method for realizing recording at higher speed and higher density has been researched, and among them, a recording method called overwrite has attracted attention. This overwrite method has an advantage that the time required for recording can be shortened because information already recorded can be rewritten directly without the need for erasing information.

Hereinafter, the overwrite method will be described together with the conventional recording method.

In order to simplify the explanation, it is assumed that the magnetization direction of the perpendicular magnetization film as the recording medium is aligned in a predetermined direction, for example, upward in a direction orthogonal to the film surface. In the case of recording, a laser beam is irradiated onto a portion to be recorded in a high output state to raise the recording portion to a temperature near or above the Curie temperature or magnetic compensation temperature of the recording medium. As a result, the value of the coercive force in the recording area becomes almost "0", so by applying a downward magnetic field in the direction perpendicular to the film surface from the outside, the magnetization in the recording area is reversed downward, and recording is performed. Be seen.

At the time of reproducing information, a low output laser beam is irradiated in a range in which magnetization reversal due to temperature rise does not occur, and information is optically detected based on a phenomenon in which the rotation direction of the polarization plane differs depending on the magnetization direction.

By the way, for the area where information is already written,
The rewriting method when writing new information is
(I) A method of recording new information after initializing by reorienting the magnetization direction of the recording medium to a fixed direction by the erasing operation, and (ii) adding a device to the recording medium or the external magnetic field generator. There are two overwrite methods, in which information is directly rewritten without an erase operation.

Among them, in the method (i), an erasing dedicated head is separately provided, or if there is only one magnetic head, erasing is performed and then recording is performed. However, the provision of an erasing head leads to high cost and an increase in the size of the apparatus.
If only one is used, rewriting will take a long time.

On the other hand, in the method (ii), a method in which the external magnetic field applying device is devised, that is, the laser beam is held in a high output state, and the direction of the external magnetic field is modulated upward and downward according to the information to be recorded The method seems to be the most promising, as it does not require a significant change in the recording medium from the conventional one.

By the way, when switching the direction of the external magnetization at a very high frequency, for example, about 10 MHz for high density recording, it is necessary to make the coil and the coil core in the external magnetic field generator sufficiently small. Therefore, since the generated magnetic field strength and the magnetic field generation region are also reduced, the magnetic head and the recording medium must be sufficiently close to each other, specifically, a distance of several μm to several tens of μm. At that time, considering that surface wobbling, that is, unevenness in the circumferential direction exists on the surface of the recording medium, if the magnetic head is of a fixed type, it is difficult to obtain the above-mentioned minute interval.

Therefore, a floating magnetic head is adopted which is urged toward the surface side of the magneto-optical memory element by a suspension such as a leaf spring and levitated from the surface of the magneto-optical memory element by the airflow generated by the rotation of the magneto-optical memory element. It is possible to do it. It should be noted that such a flying type magnetic head is adopted in an existing hard disk, and the flying height of the hard disk is usually on the order of submicron.

By the way, in magneto-optical recording using the above-mentioned floating magnetic head, the floating magnetic head maintains a constant flying height due to an airflow generated between the floating magnetic head and the magneto-optical memory element during constant speed rotation of the magneto-optical memory element. However, it is necessary to support the levitation type magnetic head by some method at the time of starting and ending the rotation of the magneto-optical memory element and during the stop of the magneto-optical memory element. As the supporting method, (i) a method of supporting the floating magnetic head so that the floating magnetic head does not come into contact with the magneto-optical memory element while the magneto-optical memory element is stopped, etc., (ii) There is a method of sliding or contacting a floating magnetic head on the magneto-optical memory element at the start, end, and stop of rotation of the magneto-optical memory element.

Among them, the method (i) has a problem that the supporting mechanism is considerably complicated. On the other hand, the method (ii) is generally used in the field of hard disks, and CSS (contact start
And stop) method. In this CSS method, first, the sliding resistance of the surface of the magneto-optical memory element becomes extremely important. In the existing hard disk, this lubricating layer having excellent sliding resistance is formed on the recording medium.
The lubricating layer is, for example, a fluorine-based lubricating oil (mainly perfluoropolyether) that is a liquid lubricant, or a solid lubricant.
It is formed by applying PTFE (polytetrafluoroethylene) or the like.

Further, in the CSS method, it is necessary to prevent information destruction due to head crash at the start and end of rotation, that is, when the flying magnetic head slides. For this reason, in the hard disk, the flying magnetic head is normally slid and contacted in an area dedicated to CSS which is set on the inner circumference side of the recording area. Also in the magneto-optical recording / reproducing apparatus, it is considered preferable to slide the flying magnetic head in a region other than the recording region.

By the way, the conventionally proposed magneto-optical memory device is
For example, as shown in FIGS. 5 (a) and 5 (b), the structure includes a transparent substrate 1, a recording medium layer 2, a protective resin layer 3, and a center hub 4.

Polycarbonate, which can be mass-produced by injection molding, is often used as the translucent substrate 1. The translucent substrate 1 has track and address information for guiding a light beam used for recording and reproducing information to a predetermined position. A guide track in which is recorded and a glass address groove 1a are formed. The guide track and the guide address groove 1a are formed simultaneously with the molding of the translucent substrate 1 by a stamper provided in a molding die (not shown) during injection molding. At this time, the member for fixing the stamper in the mold, that is, the so-called suntaper pressing, also forms the suntapa pressing groove 1b as a subordinate.

The recording medium layer 2 is formed in a state of covering the guide track and the guide address groove 1a. For example, the first transparent dielectric film, the rare earth-transition metal alloy thin film which is a magneto-optical recording medium are sequentially arranged from the transparent substrate 1 side. It has a multi-layer structure in which the second transparent dielectric and the reflective film are laminated (only one layer is shown in the figure).

The protective resin layer 3 serves to prevent damage and dust from adhering to the recording medium layer 2 and to prevent oxidation. As the material of the protective resin layer 3, an ultraviolet curable resin which is excellent in water resistance and environment resistance and is advantageous in terms of workability and process time is often used. The protective resin layer 3 is mainly formed by a spin coating method. At that time, the ultraviolet curable resin is, for example, a suntapa holding groove.
After being dropped on the outer edge portion of 1b and applied by spin coating while covering the recording medium layer 2, it is irradiated with ultraviolet rays to be cured.

The center hub 4 is a hole 1c provided in the center of the transparent substrate 1.
Since there is usually a slight eccentricity between the center of the disk and the guide track and the guide address groove 1a, the jig is a jig for absorbing the eccentricity and mounting the magneto-optical memory element on the rotary spindle of the recording / reproducing apparatus. The center hub 4 is provided with a guide hole 4a for mounting the rotary spindle 5 (see FIG. 6B) of the recording / reproducing apparatus. The center hub 4 is made of stainless steel, such as SUS430, because a magnet is often attached to the rotary spindle 5.

Further, as the shape of the center hub 4, as shown in FIG. 5 (b), a shape in which an outward flange 4b is formed at the upper end is often used, and the outward flange 4b is used as the recording medium layer 2 on the transparent substrate 1. It is attached to the surface on which is formed an appropriate adhesive, for example, an epoxy adhesive, a silicone adhesive, an ultraviolet curable resin or a double-sided tape.

FIGS. 6A and 6B show a recording / reproducing apparatus for performing recording / reproducing on the magneto-optical memory element by the CSS method.

The magneto-optical memory element shown in FIGS. 5A and 5B is magnet-mounted on the rotary spindle 5, and the floating magnetic head 6 is arranged above the magneto-optical memory element in the figure. The floating magnetic head 6 is supported by a projecting end of a suspension 7 made of a leaf spring, and the base end of the suspension 7 is connected to a support base 8. Flying magnetic head 6
Includes a slider 6a that slides on the magneto-optical memory device, and a magnetic field generating member 6b that includes a coil and a coil core (not specifically shown).

On the other hand, an optical head 9 including an optical system unit is arranged on the lower side of the magneto-optical memory device in the figure. Since the optical head 9 and the floating magnetic head 6 need to move in the radial direction of the magneto-optical memory element in conjunction with each other, the support base 8 is connected to the optical head 9. The objective lens 9a of the optical head 9 is arranged at a position corresponding to the magnetic field generating member 6b of the floating magnetic head 6.

In the above-mentioned configuration, the range in which the flying magnetic head 6 can slide by the CSS method is tentatively calculated as follows.

First, assuming that the transparent substrate 1 has a diameter of 3.5 inches (8.6 mm), which is expected to be most demanded for consumer use,
The recording area in which the guide track and the guide address groove 1a are provided has a radius of 22 to 40 mm. In order to secure the magneto-optical recording characteristics in this recording area, the radius of the recording medium layer 2 is set.
It is desirable to form r ₁ ′ (FIG. 5 (a)) = 20.5 mm to radius r ₂ ′ = 41.5 mm.

Further, the size of the slider 6a in the flying type magnetic head 6 is determined by the flying characteristics and the like, but a sliding surface of about 4 mm in the radial direction and about 5 mm in the circumferential direction is required for the above magneto-optical memory element. Become.

Considering each of the above sizes, it is difficult to slide the flying magnetic head 6 on the outer peripheral side of the recording area of the magneto-optical memory element, and the sliding area (CSS area) is inevitably recorded. It is on the inner side of the area. Here, in order to avoid destruction of information in the recording area, the recording area has a radius r ₁ ′ =
If it is provided outside of 20.5 mm, it is preferable that the CSS area is provided within a radius of 20 mm.

Next, considering how far the CSS area can be located on the inner peripheral side, the inner peripheral restriction does not cause contact between the outer peripheral surface of the rotary spindle 5 and the inner peripheral end of the optical head 9. It is decided from the point that.

The outer diameter of the rotary spindle 5 is determined by the motor torque and the area of the clamping zone that serves as a reference surface when the magneto-optical memory element is mounted.
(Radius 10.5 mm). On the other hand, the optical head 9 is an objective lens
An actuator (not shown) for stably performing the servo of the light beam centering on 9a is provided, and since it is covered with a housing for protecting optical components from dust and the like, the optical head The minimum distance to the inner edge of is 8.
About 5 mm is required. Due to these dimensions, the center position of the light beam (that is, the position of the magnetic field generating member 6b) where the rotary spindle 5 and the optical head 9 do not contact is outside the radius of 19 mm.

Therefore, the radial position of the magnetic field generating member 6b during CSS operation is in the range of 20 to 19 mm in radius, and the floating magnetic head 6 is
The area where CSS operation is performed is limited to a very limited range.

Further, as described above, the suntaper pressing groove 1b on the transparent substrate 1 is formed as a secondary by simply transferring the suntapa pressing member for fixing the suntapa to the mold to the transparent substrate 1. Therefore, the formation position of the suntapa pressing groove 1b cannot be shifted to the inner peripheral side so much, and even if it is shifted to the innermost peripheral side, the outer peripheral end is a position with a radius of about 15 mm (note that the suntapa The holding groove 1b has a groove width of about 1 mm).

Further, the center hub 4 has an adhesive strength to the transparent substrate 1,
It is necessary to secure a certain adhesion area from the viewpoint of flatness, and the diameter is, for example, about 28 mm. As described above, the CSS area is also limited in terms of the position of the suntapa pressing groove 1b, the bonding area of the center hub 4, and the like.

[Problems to be Solved by the Invention]

From the above points, the area that can perform CSS operation is a radius of 15 to 20 m.
It is an extremely narrow range of m. As a result, the magnetic field generation member 6b
The shape of the flying magnetic head 6 including the above is restricted, and the degree of freedom regarding the flying characteristics is reduced.

Further, the protective resin layer 3 for protecting the recording medium layer 2 is formed concentrically with the outer peripheral edge of the suntapa pressing groove 1b as a reference. By the way, since the floating magnetic head 6 obtains a floating force by the air flow generated between the floating magnetic head 6 and the surface of the protective resin layer 3, the slider 6 of the floating magnetic head 6 is operated during CSS operation.
a The protective resin layer 3 must be present so as to face the entire surface.
In that case, if a part of the slider 6a shifts inward from the protective resin layer 3, the turbulence of the air flow adversely affects the flying characteristics.

Even if the slider 6a does not slip inward from the protective resin layer 3, the edge of the protective resin layer 3 and the edge of the slider 6a are extremely close to each other in the configuration of FIGS. 6 (a) and 6 (b). However, there is concern about turbulence in the air flow, so it cannot be said that it is in an ideal state.

Further, since the protective resin layer 3 is focused on environment resistance such as water resistance and moisture resistance for protecting the rare earth transition metal alloy thin film which is extremely easily oxidized, it has sliding resistance and abrasion resistance against CSS operation. In terms of wear resistance, sufficient characteristics were not obtained, and the slider
There are problems such as 6a sticking to the protective resin layer 3 and abrasion powder. A protective resin that has both sliding resistance, abrasion resistance and environmental resistance is still under development. On the other hand, it has been confirmed that a fluoropolymer material having excellent sliding resistance and abrasion resistance cannot provide sufficient environment resistance.

Therefore, it is easily conceivable to further form a fluoropolymer resin on the protective resin layer 3, but this leads to an increase in the number of steps and cost, and the affinity between the two resins is insufficient. There is a concern that this is not an effective method.

[Means for solving the problem]

In order to solve the above problems, a magneto-optical memory device according to the present invention comprises a substrate, a magneto-optical recording medium formed on the substrate, a protective resin layer covering the magneto-optical recording medium, and a magneto-optical recording medium. In a magneto-optical memory element having a center hub attached to the substrate on the inner peripheral side and recording information using a floating magnetic head, a concave step on the inner peripheral side from the formation position of the magneto-optical recording medium on the substrate The center hub is attached to the concave stepped portion so as to be substantially flush with the protective resin layer, and the sliding / contact area of the floating magnetic head is provided on the center hub. To do.

Further, in the method of manufacturing a magneto-optical memory element according to the present invention, in manufacturing the magneto-optical memory element described above, after attaching the center hub to the concave stepped portion of the substrate, it is adhered to the outer peripheral end of the center hub to form the protective resin layer. It is characterized in that it is formed so as to be substantially flush with the center hub.

[Action]

According to the magneto-optical memory element of the present invention, since the floating magnetic head slides and contacts on the center hub, abrasion powder is generated and Stable with less scratches
You will be able to perform CSS actions. Further, since the configuration of the present invention can be realized by only slightly increasing the outer diameter of the conventional center hub, no disadvantage occurs in terms of cost and man-hours.

In addition, since there is a sufficiently large space above the center hub, the freedom of the shape of the floating magnetic head increases, and so does the freedom of setting the floating characteristics. There is no fear of protruding from above, and it is possible to stabilize the floating characteristics.

Further, since the concave step portion is provided on the substrate and the center hub is attached to the concave step portion, the center hub and the protective resin layer can be made to be substantially flush with each other, which allows the floating magnetic field to be formed. Even when the head passes through the boundary between the center hub and the protective resin layer, there is no risk of head crash.

On the other hand, according to the method of manufacturing a magneto-optical memory device of the present invention, the protective resin layer is formed after the center hub is mounted on the substrate, so that the protective resin layer is formed by closely contacting the outer peripheral edge of the center hub. The manufactured magneto-optical memory device can be manufactured with good reproducibility. In this magneto-optical memory element, since there is no gap between the outer peripheral edge of the center hub and the protective resin layer, the floating characteristic does not change even when the floating magnetic head passes through the boundary between the center hub and the protective resin layer. It does not occur, and head crush is even less likely to occur.

〔Example〕

One embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

The magneto-optical memory device according to this embodiment is shown in FIG.
As shown in FIGS. 3B and 3A, the transparent substrate 11
A recording medium layer 12 as a magneto-optical recording medium formed on the transparent substrate 11 (not shown in FIG. 2B for simplification of the figure), and protection for covering the transparent substrate 11. A resin layer 13 and a center hub 14 attached to the center of the transparent substrate 11 are provided.

The translucent substrate 11 is obtained by injection molding a translucent resin such as polycarbonate, and the optical head 20
A guide track and a guide address groove in which track information and address information for guiding a laser beam emitted from (see FIG. 1B) to a desired recording / reproducing portion are recorded.
11a (not shown in FIG. 2 (b)) is simultaneously formed at the time of injection molding.

Further, a concave step portion 11b having an inner diameter slightly larger than the outer diameter of the outward flange 14b of the center hub 14 is provided in the range where the center hub 14 on the inner peripheral side of the recording medium layer 12 on the translucent substrate 11 is bonded. ing. The recessed step portion 11b is formed by devising the shapes of the stamper and the stamper pressing member (not shown) when the translucent substrate 11 is manufactured by injection molding.

The recording medium layer 12 is formed so as to cover the guide track and the guide address groove 11a on the transparent substrate 11. The recording medium layer 12 includes, for example, a first transparent dielectric film, a rare earth transition metal alloy thin film that is a magneto-optical recording medium, a second transparent dielectric film, and a sequential metal reflective film in that order from the transparent substrate 11 side. It has a laminated multi-layer structure (only one layer is shown in FIG. 3A for simplicity).

The protective resin layer 13 covers the recording medium layer 12 and is formed over a slightly wider radius range than the recording medium layer 12 so as to prevent the recording medium layer 12 from being oxidized and damaged. As a material for the protective resin layer 13, for example, an ultraviolet curable resin is used.

The center hub 14 absorbs the eccentricity between the center of the hole 11c at the center of the transparent substrate 11 and the guide track and the guide address groove 11a, while recording the magneto-optical memory device as shown in FIGS. 1 (a) and 1 (b). It is for mounting on the rotary spindle 21 of the reproducing apparatus. The outer diameter of the center hub 14 is made larger than that of the conventional one so that the floating magnetic head 16 can slide and contact on the center hub 14.

As the material of the center hub 14, a stainless steel (SUS430 etc.) is used because the center guide hole 14a is used and it is necessary to attach a magnet to the rotary spindle 21 and in terms of workability.
Is used.

The center hub 14 has an outward facing flange 14b provided on the upper end.
The adhesive layer 15 is formed in the concave step portion 11b of the transparent substrate 11 at
Are glued by. As the adhesive layer 15, a quick-drying epoxy adhesive, an ultraviolet curable resin, or the like is used in consideration of adhesive strength, workability, and the like.

The dimensions of each part of the magneto-optical memory element are, for example, an outer diameter of the transparent substrate 11 of 86 mm and an inner diameter of the central hole 11c of 15 m.
When a polycarbonate substrate having a thickness of m and a thickness of 1.2 mm is used, the area where the guide track and the guide address groove 11a are provided has a radius of 22 to 40 mm. Further, the area where the recording medium layer 12 is formed has a radius r ₁ (FIG. 2A) = 20.5 mm to a radius r ₂
＝ 41.5mm range.

When the area where the floating magnetic head 16 slides / contacts (CSS) is located on the inner peripheral side of the position with a radius of 20 mm, the outer diameter of the center hub 14 is preferably 40 mm. Further, the plate thickness of the center hub 14 is set to about 0.3 mm in consideration of the attraction by the magnet and mechanical characteristics (rigidity, flatness characteristics, etc.).

In the magneto-optical memory device described above, the center hub 14 and the protective resin layer 13 may have the same surface height, or may have a slight height deviation that does not adversely affect the floating characteristics of the floating magnetic head 16. is important.

That is, the floating magnetic head 6 slides and floats in the sliding / contact area (CSS area) on the center hub 14 with the start of rotation of the magneto-optical memory element, and then the laser emitted from the optical head 20. The center hub operates to access the magneto-optical memory element in the radial direction in conjunction with the beam.
If there is a large height difference at the boundary between 14 and the protective resin layer 13,
Head crash may occur.

Therefore, as described above, the thickness of the center hub 14 is 0.3 mm.
If the adhesive layer 15 has a thickness of about 0.05 mm and the protective resin layer 13 has a thickness of about 0.01 mm (10 μm), the concave stepped portion 11b is set to have a depth of about 0.34 mm, thereby providing a center hub. The surface height of the outward flange 14b of 14 and the surface height of the protective resin layer 13 can be made substantially the same.

Considering that the center hub 14 has a role of absorbing the eccentricity of the guide track and the guide address groove 11a, the inner diameter of the concave step portion 11b needs to be slightly larger than the outer diameter of the center hub 14 as described above. . Specifically, the concave step
The inner diameter of 11b may be about 0.3 mm larger than the outer diameter of the center hub 14 to be about 40.3 mm.

As shown in FIGS. 1 (a) and 1 (b), the recording / reproducing apparatus using the magneto-optical memory element of this embodiment has a center hub 14 at the start and end of rotation of the magneto-optical memory element and at the time of stop thereof.
Slider 16a that slides and contacts on the outward flange 14b of
And a flying magnetic head 16 comprising a magnetic field generating member 16b attached to the slider 16a.
Is urged toward the magneto-optical memory device side by a suspension 17 whose base end is fixed to a support base 18.

An optical head 20 having an objective lens 20a at a position corresponding to the magnetic field generating member 16b is arranged below the magneto-optical memory element. The support base 18 is connected to the optical head 20, and the optical head 20 and the floating magnetic head 16 are integrally moved in the radial direction of the magneto-optical memory element.

In addition, the magneto-optical memory device has a guide hole 14 in the center hub 14.
For example, a magnet is attached to the portion a by the rotary spindle 21 and is rotated by a spindle motor (not shown).

In the above configuration, the slider of the flying magnetic head 16
16a is the center hub 1 when the rotation of the magneto-optical memory element is stopped.
4 is touching on the outward flange 14b.

At the time of recording, the floating magnetic head 16 is levitated by the air flow generated between the outward flange 14b and the slider 16a as the magneto-optical memory element rotates. After that, the flying magnetic head 16 and the optical head 20 are moved from the outward flange 14b onto the recording medium layer 12, and desired information is recorded by an overwrite method by irradiating a laser beam and applying a magnetic field.

After the recording is completed, the floating magnetic head 16 is moved again onto the outward flange 14b, and then the rotating speed of the magneto-optical memory element is gradually decreased, so that the floating magnetic head 16 slides on the outward flange 16a. After that, the magneto-optical memory device stops on the outward flange 14b as the rotation of the magneto-optical memory device stops.

In the above configuration, since the sliding / contacting operation of the floating magnetic head 16 is performed on the center hub 14 made of stainless steel such as SUS430, there is no problem in terms of wear and slidability.
Stable CSS operation can be performed.

In addition, the concave step portion 11 used for mounting the center hub 14
Since b can be formed by simply modifying the shape of the stamper pressing member when the transparent substrate 11 is injection-molded, there is no disadvantage in comparison with the conventional method in terms of manufacturing cost and man-hours.

Furthermore, it is not necessary to change the material of the center hub 14 from the conventional one, and only the outer diameter needs to be increased.Therefore, compared to the case where another member or a lubricating layer is provided for CSS operation, the cost, It is advantageous in terms of man-hours.

Further, as is clear by comparing FIGS. 1 (a) and (b) with FIGS. 6 (a) and (b) showing the conventional example, in the present embodiment, the outward flange having a larger outer diameter than the conventional one. Since the floating magnetic head 16 is slid on 14b, the sliding / contact area can be made much wider than before. As a result, the degree of freedom in the shape of the slider 16a of the flying magnetic head 16 is increased, so that the degree of freedom in setting the flying characteristics (flying amount, etc.) is increased, and the flying magnetic head 16 during sliding is increased.
However, since there is no fear of protruding from the outward flange 14b, which is a sliding region, it is possible to stabilize the floating characteristic.

By the way, in the magneto-optical memory element of the present embodiment, the inner diameter of the concave step portion 11b is slightly larger than the outer diameter of the center hub 14. For example, as described above, when the inner diameter of the recessed stepped portion 11b is made larger than the outer diameter of the center hub 14 by about 0.3 mm, the space between the outer peripheral surface of the outward flange 14b and the inner side surface of the recessed stepped portion 11b is increased.
A gap of about 0.15 mm occurs. If this gap is left as it is when the magneto-optical memory element is completed, the air flow on the surface of the magneto-optical memory element is disturbed, which may adversely affect the flying characteristics of the floating magnetic head 16. Therefore, it is preferable that the above gap does not exist when the magneto-optical memory device is completed.

However, when the magneto-optical memory element of this embodiment is manufactured, if the center hub 14 is attached after forming the recording medium layer 12 and the protective resin layer 13 on the translucent substrate 11 as in the conventional case, as shown in FIG. outward flange 14 as shown in b)
There is a problem that a gap 24 remains between the outer peripheral surface of b and the inner surface of the concave step portion 11b.

That is, before the center hub 14 is attached, the transparent substrate 11
When the protective resin layer 13 is formed by the spin coating method, the liquid ultraviolet curable resin, which is the material of the protective resin layer 13, is dropped with reference to the corner A at the upper end of the inner side surface of the concave step 11b, and the spinner is rotated. Thus, it spreads concentrically on the translucent substrate 11 and the recording medium layer 12, but a slight wraparound occurs within the concave stepped portion 11b. Therefore, after the ultraviolet curable resin is cured to form the protective resin layer 13, the center hub 14
, The inner surface of the concave step 11b and the center hub 1
There will be a gap 24 between 4 and 4.

To put it the other way around, the above-mentioned UV curable resin causes the concave step 11
If the protective resin layer 13 is formed into the concave stepped portion 11b by flowing into b, it hinders the attachment of the center hub 14, so if the protective resin layer 13 is formed before attaching the center hub 14, the gap 24 is essential. As described above, in this embodiment, if the center hub 14 is attached after the protective resin layer 13 is formed as in the conventional case, the gap 24 cannot be eliminated.

Therefore, in this embodiment, after the center hub 14 is attached, the protective resin layer 13 is formed to eliminate the gap between the two.

That is, in this embodiment, when manufacturing the magneto-optical memory device, first, the guide track and the guide address groove 11 are formed.
The translucent substrate 11 provided with a and the concave step portion 11b is obtained by injection molding.

Then, if necessary, after pre-processing such as cleaning and baking (for degassing), the recording medium layer 12 made of a multilayer film is formed by sputtering.

Next, the outward flange 14b of the center hub 14 is provided on the concave step portion 11b of the transparent substrate 11 on which the recording medium layer 12 is formed, and the guide hole 14a is concentric with the guide track and the guide address groove 11a. Adhesion is made by the adhesive layer 15. At this point, the surface of the outward flange 14b is slightly higher than the surface of the recording medium layer 12 formed on the translucent substrate 11.

Then, the process of forming the protective resin layer 13 is performed. First, the fourth
As shown in FIG. 3A, the transparent substrate 11 on which the recording medium layer 12 (not shown in the figure) is formed and the center hub 14 is attached is mounted on the rotary table 22 of the spinner. The attachment is performed by the magnet 23 installed on the rotary table 22, and if necessary, the vacuum chuck may be performed at the same time.

In the above-mentioned mounted state, first, in order to fill the gap between the outer peripheral surface of the outward flange 14b and the inner surface of the concave stepped portion 11b, the ultraviolet curable resin 13 'is removed from the outer peripheral end of the outward flange 14b of the center hub 14. It is dropped on the translucent substrate 11 slightly outside. The dropping of the ultraviolet curable resin 13 ′ may be performed while the dropping port is fixed and the rotary table 22 is gently rotated, or while the dropping port is moved in the circumferential direction of the transparent substrate 11. You may drop it.

The ultraviolet curable resin 13 'dropped as described above spreads to the outer peripheral side and the inner peripheral side of the translucent substrate 11, but the inner peripheral side is the outward flange 14b as shown in FIG. 4 (a). 3A, the protective resin layer 13 after curing is also formed in the gap between the inner surface of the concave step portion 11b and the outer surface of the outward flange 14b, as shown in FIG. 3A. As it is formed
It also flows into the gap.

Next, while continuing to drop the ultraviolet curable resin 13 'while rotating the rotary table 22 at a predetermined speed, the ultraviolet curable resin 13' is placed on the outer peripheral side of the outward flange 14b.
Cover the entire surface of 1 (Fig. 4 (b)).

Thereafter, as shown in FIG. 4 (c), by irradiating ultraviolet rays from above, the ultraviolet curable resin 13 'is cured and the protective resin layer 13 is formed.

As described above, according to the manufacturing method of the present embodiment, it is possible to provide the magneto-optical memory element in which there is no gap between the outer peripheral surface of the outward flange 14b and the inner side surface of the concave step portion 11b.

In the above embodiment, the center hub 14 is made of SUS430.
Although it is made of stainless steel, it may be made of other metals. However, it is desirable that the magnet can be attracted.

Further, the corner portion A (FIG. 3 (a)) at the upper end of the inner surface of the concave stepped portion 11b has a right-angled shape.
Inner surface of concave step 11b such as arc shape and outward flange 1
The UV curable resin 13 'may have another shape which allows the UV curable resin 13' to easily flow into the gap between the 4b and 4b.

Further, in the above-described method for manufacturing the magneto-optical memory device, the center hub 14 is attached after the recording medium layer 12 is formed on the transparent substrate 11, but the center hub 14 is attached to the transparent substrate 11. After attachment, the recording medium layer 12 and the protective resin layer 13 may be formed.

Further, the translucent substrate 11 may be formed of translucent resin such as acrylic or epoxy other than polycarbonate as long as the concave step portion 11b for mounting the center hub 14 is provided. Further, the center hub 14 may be adhered with a double-sided tape or the like as long as a predetermined adhesion strength and reliability are satisfied.

〔The invention's effect〕

As described above, the magneto-optical memory device according to the present invention is provided with the concave step portion on the inner peripheral side of the formation position of the magneto-optical recording medium on the substrate, and the center hub is almost the same as the protective resin layer in the concave step portion. While being attached to form a surface,
This is a configuration in which the sliding / contact area of the floating magnetic head is provided on the center hub.

As a result, the floating magnetic head slides and contacts on the center hub, so there is less generation of abrasion powder and scratches than scratches when compared to sliding and contact on the protective resin layer. It becomes possible to perform stable CSS operation. Further, since the configuration of the present invention can be realized by only slightly increasing the outer diameter of the conventional center hub, there is no disadvantage in terms of cost and man-hours.

In addition, since there is a sufficiently large space above the center hub, the degree of freedom in the shape of the floating magnetic head increases, which in turn increases the degree of freedom in setting the floating characteristics, and the flying magnetic head slides during sliding. Since there is no fear of protruding from the center hub, which is the moving area, the floating characteristics can be stabilized.

Further, since the concave step portion is provided on the substrate and the center hub is attached to the concave step portion, the center hub and the protective resin layer can be made to be substantially flush with each other, which allows the floating magnetic field to be formed. Even when the head passes through the boundary between the center hub and the protective resin layer, there is no risk of head crash.

Further, in the method of manufacturing a magneto-optical memory element according to the present invention, in manufacturing the magneto-optical memory element described above, after attaching the center hub to the concave stepped portion of the substrate, it is adhered to the outer peripheral end of the center hub to form the protective resin layer. It is configured so as to be substantially flush with the center hub.

As a result, the magneto-optical memory element having the protective resin layer formed in close contact with the outer peripheral edge of the center hub can be manufactured with good reproducibility. In this magneto-optical memory element, since there is no gap between the outer peripheral edge of the center hub and the protective resin layer,
Even when the flying type magnetic head passes through the boundary between the center hub and the protective resin layer, the flying characteristics do not change, and the head crash is further less likely to occur.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1A is a schematic plan view showing a magneto-optical memory element and a recording / reproducing apparatus. FIG. 2B is a schematic vertical sectional view of the same. FIG. 2A is a schematic plan view showing a magneto-optical memory element. FIG. 2B is a schematic vertical sectional view of the same. FIG. 3 (a) is a partially enlarged view of FIG. 2 (a). FIG. 2B is an enlarged view of the part of the magneto-optical memory device of the present invention manufactured by the conventional manufacturing procedure. 4A to 4C are schematic vertical cross-sectional views showing the procedure for forming the protective resin layer. 5 and 6 show a conventional example. FIG. 5 (a) is a schematic plan view showing a magneto-optical memory element. FIG. 2B is a schematic vertical sectional view of the same. FIG. 6A is a schematic plan view showing a magneto-optical memory device and a recording / reproducing device. FIG. 2B is a schematic vertical sectional view of the same. Reference numeral 11 is a translucent substrate, 11b is a concave stepped portion, 12 is a recording medium layer (magneto-optical recording medium), 13 is a protective resin layer, 14 is a center hub, and 16 is a floating magnetic head.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Takahashi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Kenji Ota 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Sharp Corporation (56) References JP-A 64-64148 (JP, A) JP-A 1-220280 (JP, A) Actually opened 62-101126 (JP, U) Actually opened 2-60969 (JP, U)

Claims (2)

(57) [Claims] 1. A substrate, a magneto-optical recording medium formed on the substrate, a protective resin layer covering the magneto-optical recording medium, and a center hub attached to the substrate on the inner peripheral side of the magneto-optical recording medium. In a magneto-optical memory element for recording information using a floating magnetic head, a concave step portion is provided on an inner peripheral side of a formation position of a magneto-optical recording medium on the substrate, and the center hub is protected by the concave step portion. A magneto-optical memory device, which is mounted so as to be substantially flush with a resin layer, and has a sliding / contact area of a floating magnetic head provided on a center hub. 2. The method of manufacturing a magneto-optical memory device according to claim 1, wherein after the center hub is attached to the concave step portion of the substrate, the center hub is brought into close contact with the outer peripheral end of the center hub so as to be substantially flush with the center hub. A method of manufacturing a magneto-optical memory element, characterized in that a protective resin layer is formed on the substrate.