JP3211390B2 - Method of holding magnetic plate to disk substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk provided on an information signal recording disk, such as an optical disk or a magneto-optical disk, on which a desired information signal is recorded. About the method.

[0002]

2. Description of the Related Art Hitherto, there has been proposed an information signal recording disk on which a desired information signal is recorded, such as an optical disk or a magneto-optical disk. This kind of disc is capable of recording information signals at a high density, so that a very small disc has been proposed. For example, there has been proposed an optical disk or a magneto-optical disk having a diameter of about 64 mm and capable of recording a sound signal for about 74 minutes.

A magneto-optical disk having such a small diameter and capable of recording information signals at a high density is mounted on a disk rotation drive and rotated at a high speed. Then, while being rotated at a high speed, a fine recording track provided on a signal recording layer formed on one main surface of the magneto-optical disk is irradiated with a light beam emitted from the optical pickup, and a magnetic head is provided. A desired information signal is recorded by applying an external magnetic field which is subjected to a magnetic field modulation according to an information signal to be recorded from an external magnetic field generating device.

In order to accurately irradiate a fine recording track with a light beam while being rotated and driven at a high speed,
The magneto-optical disk must be securely integrated with the disk table of the disk rotation drive device and mounted with the rotation center positioned with high precision on the axis of the disk table.

Incidentally, in order to reliably integrate the magneto-optical disk with the disk table and to position and mount it with high precision, a magnetic plate for magnetic attraction such as a metal plate made of a magnetic material disposed on the magneto-optical disk side is used. Is attracted by a magnet provided on the disk table side, and the magneto-optical disk is chucked on the disk table.

[0006] A magneto-optical disk 1 used in a magnet chucking system utilizing the attractive force of the magnet.
As shown in FIG. 12, a disk substrate 2 formed by molding a synthetic resin such as a transparent polycarbonate resin into a disk shape is provided. One main surface 2 of the disk substrate 2
On the a side, an information signal recording layer on which a desired information signal is recorded is formed. Then, the disk substrate 2
The other main surface 2b opposite to one main surface 2a on which the information signal recording layer is formed is formed as an information signal writing / reading surface, and a light beam is applied to the signal recording layer from the writing / reading surface side. Thus, recording or reproduction of a desired information signal is performed.

In the center of the disk substrate 2,
As shown in FIG. 12, a center hole 3 is formed in which a centering member disposed on the disk rotation drive side engages. Further, one main surface 2 of the disk substrate 2
A metal plate 4 which is a magnetic plate is disposed at the center of the a side so as to close the center hole 3. This metal plate 4
Is a center hole 3 on one main surface 2a side of the disk substrate 2.
Are arranged so as to fit into the metal plate storage recess 5 formed around the disk substrate 2 and are joined to the disk substrate 2 using an adhesive 6 such as a double-sided adhesive tape.

As described above, in the magneto-optical disk 1 in which the metal plate 4 is attached to the disk substrate 2 by using the adhesive 6, the loading and unloading of the disk rotation drive unit with respect to the disk table is repeated. 4 may be easily separated from the disk substrate 2. That is,
This is because a load at the time of loading / unloading of the disk table is applied to a joining portion of the metal plate 4 to the disk substrate 2 and the adhesive 6 is deteriorated.

In order to solve the problems arising from attaching a metal plate using such an adhesive, the applicant of the present application has proposed a magneto-optical disk in which the metal plate is attached to a disk substrate without using an adhesive. Has been proposed.
As shown in FIG. 13, the magneto-optical disk 11 surrounds a center hole 13 on one main surface 12a of a disk substrate 12 made of a synthetic resin such as a transparent polycarbonate resin on which an information signal recording layer is formed. A metal plate storage recess 15 is provided so that the metal plate 14 is stored therein, and a convex portion 16 for caulking of the metal plate 14 is protruded from the outer peripheral side of the metal plate storage recess 15. The plurality of convex portions 16 are provided at equal intervals on the outer peripheral edge side of the metal plate housing concave portion 15.

After the metal plate 14 is accommodated in the metal plate accommodating recess 15, heat is applied to the convex portion 16, and the metal plate 14 is heated.
As shown in FIG. 4, by thermally deforming the distal ends of the convex portions 16 toward the metal plate housing concave portions 15, the metal plate 1 is supported by the support pieces 16 a protruding from the distal ends of the convex portions 16.
4 is mounted in the disk substrate 12 while being supported in the metal plate storage recess 15.

In the magneto-optical disk 11 in which the metal plate 14 is supported and mounted by the support pieces 16a projecting from the tip of the projection 16 formed integrally with the disk substrate 12, the metal plate Since the disk drive 14 is firmly supported by the disk substrate 12, even if the disk rotation drive is repeatedly mounted to and removed from the disk table, the disk drive can be securely mounted on the disk substrate 12 without peeling or the like. Becomes possible.

[0012]

However, in order to form the convex portion 16 for supporting the metal plate 14 on the disk substrate 12 as described above, the structure of a mold for molding the disk substrate 12 becomes complicated. In addition, processing of the mold becomes difficult.

When the projection 16 is formed intermittently on the outer peripheral side of the metal plate housing recess 15, the disk substrate 12
In molding, the flow of the synthetic resin material melted at the portion where the convex portion 16 is formed becomes uneven, and further, a shift occurs in the curing time of the synthetic resin material, and a so-called weld line is generated. There is a possibility that the uniformly cured disk substrate 12 cannot be formed. Further, if the disk substrate 12 is not cured uniformly, internal stress remains in the disk substrate 12, causing birefringence and the like in the disk substrate 12, thereby deteriorating optical characteristics. In particular, when birefringence occurs in the disk substrate 12, when it is configured as the magneto-optical disk 11, writing or reading of an information signal may be defective.

In order to solve the problem caused by the intermittent formation of the metal plate supporting projection as described above, a series of ring-shaped projections are provided on the outer peripheral side of the metal plate housing recess. A disk substrate to be formed is conceivable. However, it is extremely difficult to perform caulking to support a metal plate arranged in a metal plate storage recess by, for example, uniformly thermally deforming a series of ring-shaped protrusions, which is poorly feasible. It is.

It is also conceivable to perform caulking to support a metal plate by partially thermally deforming a part of a series of ring-shaped convex portions. However, the metal plate is supported on a disk substrate. After that, portions that have not been thermally deformed remain in a protruding shape. Therefore, the thickness of the disk substrate itself is increased only in the protruding portions, and the magneto-optical disk formed using the disk substrate is also increased. Then, it becomes difficult to design a disk cartridge for storing the magneto-optical disk. That is, the thickness of the disk cartridge is defined to be constant so that it can be used with versatility.

Accordingly, the present invention facilitates the processing of a mold for molding a disk substrate, facilitates the molding of the disk substrate, prevents deterioration of the optical characteristics of the disk substrate after molding, and provides birefringence. It is possible to form the disk substrate of the information signal recording disk without causing the like, etc., while maintaining the smoothness of the main surface side of the disk substrate, and securely holding the magnetic plate to the disk substrate, An object of the present invention is to provide a method for holding a magnetic plate on a disk substrate, which makes it possible to suppress the occurrence of an adverse effect on the disk substrate due to the attachment of the magnetic plate.

Further, the present invention provides a method of holding a magnetic plate on a disk substrate which realizes simplification of an apparatus used for attaching the magnetic plate to the disk substrate and realizes quick and easy holding of the magnetic plate. The purpose is to provide.

[0018]

According to the present invention, a center hole is formed and an information signal recording layer is formed on one main surface side in order to solve the above-mentioned problems and achieve the above object. When the magnetic plate is held in the magnetic plate housing recess formed around the center hole on one main surface side of the synthetic resin disk substrate, the contact portion on the distal end side of the vibration applying element and the contact on the base end side The ultrasonic vibration is applied by bringing at least two points of the portion into contact with the peripheral edge of the magnetic plate housing recess, and at least a part of the peripheral edge of the magnetic plate housing recess is thermally deformed. This is to hold a magnetic plate.

Further, according to the present invention, the contact area of the vibration applying element for thermally deforming the peripheral edge of the magnetic plate accommodating concave portion with respect to the disk substrate is increased as compared with the contact portion on the distal end side. It is like that.

[0020]

According to the method of the present invention, the vibration applicator is used in a state where two points, a contact portion on the distal end side and a contact portion on the base end side, of the vibration applicator are brought into contact with the periphery of the magnetic plate accommodating recess accommodating the magnetic plate. When the ultrasonic vibration is applied to the disk substrate via the magnetic disk, a part of the periphery of the magnetic plate storage recess contacted by the vibration applicator is thermally deformed and protrudes into the magnetic plate storage recess. The magnetic plate accommodated in the magnetic plate accommodating recess is held on the magnetic plate accommodating recess with the outer peripheral edge side supported by a protruding piece projecting into the magnetic plate accommodating recess.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment in which the method of the present invention is applied to a magneto-optical disk having a diameter of 64 mm will be described with reference to the drawings. As shown in FIG. 1, a magneto-optical disk 21 to which the method of the present invention is applied has a disk substrate 22 formed by molding a synthetic resin material such as a polycarbonate resin having the transparency of the present invention. The disk substrate 22 has a diameter R of about 64 mm and a thickness T of about 1.2 mm.
mm.

The magneto-optical disk 21 formed by using the disk substrate 22 has a signal recording layer on which a desired information signal is recorded on one main surface 2a side of the disk substrate 22 to form a signal. A recording portion provided on one main surface 22 of the disk substrate 22 on which the information signal recording layer is formed;
The other main surface 22b opposite to a is formed as an information signal write / read surface, and the information signal is recorded / reproduced by irradiating the signal recording layer with a light beam from the write / read surface. Become.

As shown in FIGS. 1 and 2, the center of the disk substrate 22 constituting the magneto-optical disk 21 is
A center hole 23 for engaging a centering member provided at the center of a disk table constituting a disk rotation drive device provided in the recording / reproducing apparatus is formed.
The center hole 23 is formed so as to penetrate through the disc substrate 22 and is formed so that the center thereof coincides with the center of curvature of a recording track formed concentrically or spirally on the signal recording layer.

As shown in FIG. 2, an annular protruding portion 24 is formed integrally around the center hole 23 at the center of the disk substrate 22 on the other main surface 22b side. . The protruding portion 24 is formed by increasing the depth of the center hole 23 formed in the thin disk substrate 22 so that the center hole of the centering member provided on the disk table side on which the magneto-optical disk 21 is mounted. The centering operation of mounting the magneto-optical disk 21 with the rotation center of the magneto-optical disk 21 aligned with the axis of the disk table is ensured. Further, the tip surface of the protruding portion 24 functions as a mounting reference surface 24a to be mounted on the disk table.

The protruding portion 24 is formed at least in a non-signal recording area on the inner peripheral side of the disk substrate 22 where no signal recording layer is formed, and has a protruding amount substantially equal to the thickness T of the disk substrate 22. Have been. Therefore, the portion of the disk substrate 22 where the protruding portions 24 are formed is twice as thick as the substrate main body.

An annular metal plate surrounding a center hole 23 is provided with a metal plate 25 which is a magnetic plate for attracting magnets, in the center of the disk substrate 22 on one main surface 22a side. A storage recess 26 is formed. The metal plate housing recess 26 has a diameter smaller than the outer diameter r of the protrusion 24 and is formed at a depth substantially equal to the thickness T of the disk substrate 22. Further, the opening edge side of the metal plate housing recess 26 is enlarged in diameter as compared with the inner portion, so that the metal plate 25 can be easily inserted into the metal plate housing recess 26.

As described above, the one main surface 22a side of the disk substrate 22 is a smooth surface in which only the metal plate housing recess 26 is formed.

The metal plate 2 of the metal plate storage recess 26 is formed.
A step portion 28 is formed on the inner peripheral side of the bottom surface portion serving as the mounting surface 27 of No. 5. The step portion 28 prevents the formation of projections such as burrs on the mounting surface 27 of the metal plate 25 when the metal plate housing concave portion 26 is formed, and maintains the mounting surface 27 as a smooth surface. Is to do so.

On the other hand, the metal plate 25 housed and disposed in the metal plate housing recess 6 is made of a metal material such as a stainless steel plate (SUS-430) having a thickness t of about 0.4 mm and having a magnetic property. It is formed by punching. As shown in FIG. 1, the metal plate 25 is formed in a disk shape large enough to be stored in the metal plate storage recess 26, and is stored and distributed in the metal plate storage recess 26. When installed, the central main surface portion 25a is made flush with one main surface 22a of the disk substrate 22, and the inner peripheral surface 26a of the metal plate housing recess 26 faces the peripheral edge of the metal plate 25. For this purpose, a step bending process is performed on the outer peripheral edge side. That is, the mounting piece 30 on the mounting surface 27 is formed on the outer peripheral edge side of the metal plate 25 via the bent portion 29 bent so as to hang down toward the peripheral edge.
That is, as shown in FIG. 1, the metal plate 25 is formed in a disk shape that has a concave shape as a whole.

The metal plate 25 formed as described above is held on the disk substrate 22 by the following steps and methods.

First, the disk substrate 22 formed as shown in FIGS. 1 and 2 is placed on the suction support table 101. The suction support table 101 is configured so as to be capable of positioning and supporting the mounted disk substrate 22 by suction.
As shown in FIG. 3, a disk substrate support table 103 on which the disk substrate 22 is positioned and placed is provided. The disk substrate support table 103 has a centrally protruding fitting projection 104 into which the center hole 23 of the disk substrate 22 fits.
A protrusion fitting recess 105 into which the protrusion 24 of the disk substrate 22 fits is provided around the outside.

A flexible protective sheet 106 made of silicon rubber or the like is attached to the disk substrate mounting surface of the disk substrate support table 103 which receives the other main surface 22b of the disk substrate 22. And so on. The protective sheet 106 is provided to prevent the other main surface 22b of the disk substrate 22 to be placed from being damaged or otherwise damaged.

The suction support table 101 has:
A suction mechanism is provided to support the disk substrate 22 placed on the disk substrate support table 103 by vacuum suction using a vacuum air pump. This suction mechanism opens a plurality of suction ports 107 in the disk substrate support table 103 and forms an air suction chamber 108 with an escutcheon 110 interposed between the disk substrate support table 103 and the support table main body 102. Room 10
The disk substrate 22 is sucked and supported on the disk substrate support table 103 by sucking the air of No. 8 through an air passage 109 formed in the support table main body 102 by a vacuum air pump (not shown).

The plurality of suction ports 107 are provided at positions corresponding to the outer peripheral side and the central portion of the disk substrate 22 placed on the disk substrate support table 103, and at the protruding portions to which the protruding portions 24 are fitted. Each of them is opened in the joint recess 105. By providing each suction port 107 at such a position, the entire surface of the disk substrate 22 can be almost uniformly pressed against the disk substrate support table 103 and supported.

At a position corresponding to the suction port 107 of the protection sheet 106, an opening 108 communicating with the suction port 107 is formed.

As shown in FIG. 4, the disk substrate 22 is placed on the suction support table 101 having the above-described structure, with the metal plate storage recess 26 in which the metal plate 25 is disposed facing upward. Is done. At this time, the disk substrate 22
Is inserted into the metal plate storage recess 26 and the center hole 23 through the fitting projection 10.
4, the protrusion 24 is fitted to the protrusion fitting recess 105, and the mounting position of the mounting position with respect to the suction support table 101 is achieved.

When the disk substrate 22 is mounted on the suction support table 101 in this way, the vacuum air pump is operated to suck the air in the suction air chamber 108 through the air passage 109, and the disk substrate 2 is sucked through the suction port 107.
The air between the suction support table 2 and the suction support table 101 is also sucked, and the disk substrate 22 comes into close contact with the protection sheet 106 on the suction support table 101 and is supported.

At this time, in the disk substrate 22, the center hole 23 is fitted into the fitting projection 104, and the projection 24 is fitted into the projection fitting recess 105, so that the suction support table 101 is fitted.
The suction support table 101
The exact positioning of the mounting position with respect to is achieved.

After the disk substrate 22 is mounted on the suction support table 101 as described above, the metal plate 25 is housed in the metal plate housing recess 26. At this time, the metal plate 25
As shown in FIG. 5, the placement piece 10 is placed and placed on the placement surface 27 of the metal plate storage recess 26.

At the place where the metal plate 25 is accommodated in the metal plate accommodating recess 26, the vibration applicator 112, which is a resonator of the ultrasonic wave applicator 111, is moved to the metal plate accommodating recess 26 as shown in FIG.
Contact the periphery of Vibration applicator 11 used here
2, the first contact portion 113 on the distal end side as shown in FIG.
And a second contact portion 114 on the proximal end side. The first and second contact portions 113 and 114 are provided at an interval corresponding to the diameter of the metal plate housing recess 26 so as to be able to contact opposing positions of the metal plate housing recess 26.

Then, each of the first and second contact portions 113 and 114 is formed as shown in FIG.
The vibration applicator 112 is brought into contact with the disk substrate 22 so as to correspond to the periphery of the disk substrate 22. At this time, the vibration applicator 11
2 is brought into contact with the disk substrate 22 in a constant pressurized state. When the ultrasonic application device 111 is driven when the first and second contact portions 113 and 114 are brought into contact with the periphery of the metal plate housing concave portion 26, the vibration
Oscillates ultrasonic vibrations, and the ultrasonic vibrations
Is applied to the disk substrate 22 through the contact portions 113 and 114 of the disk drive.

At this time, the ultrasonic vibration applied to the disk substrate 22 vibrates in a direction parallel to the main surface of the disk substrate 22.

When the ultrasonic vibration is applied in this manner, the first and second contact portions 113 and 11 of the vibration applying element 112
The peripheral edge portion of the metal plate housing concave portion 26 with which the substrate 4 comes into contact is heated and softened. At this time, since the vibration applicator 112 is pressurized at a predetermined pressure, the first and second contact portions 113 of the vibration applicator 112
The protrusions 31 and 32 are formed so as to protrude toward the inner peripheral side of the metal plate housing recess 26 so as to form the recesses 33 and 34 corresponding to the sizes of the metal plates 114 and 114, respectively. As shown in FIG. 7, the projecting pieces 31 and 32 are
6 protrudes above the mounting piece 30 of the metal plate 25 housed and arranged in the housing 6 and supports the mounting piece 30.

Note that the vibration applicator 112 includes first and second
The contact portions 113 and 114 are brought into contact with the peripheral portion of the metal plate housing recess 26 for a predetermined time, and the protruding pieces 31 and 32 are
Is formed and separated from the disk substrate 22 to return to the initial position.

In the present embodiment, after the protrusions 31 and 32 are formed at the radially opposed positions of the metal plate housing recess 26 as described above, the suction support table 101 is moved to 9 positions.
After rotating by 0 degree, the first and second contact portions 113 and 114 of the vibration applicator 112 are again brought into contact with the peripheral portion of the metal plate housing concave portion 26 for a predetermined time, and the ultrasonic vibration is applied to the disk substrate 22.
To form protrusions 31 and 32. That is, as shown in FIG. 8, four protruding pieces 31, 32 and 31, 32 are formed in the peripheral portion of the metal plate housing recess 26 to hold the metal plate 25 housed and arranged in the metal plate housing recess 26. I am trying to do it.

Since the ultrasonic vibration applied to the disk substrate 22 vibrates in a direction parallel to the main surface 22a of the disk substrate 22, the vibration is applied in a direction parallel to the main surface 22a of the disk substrate 22. The first and second contact portions 1 of the vibration applicator 112 of the disk substrate 22
The portion softened by the contact of 13 and 114 is displaced in a direction parallel to the main surface 22a through which the ultrasonic vibration propagates. Therefore, the protruding pieces 31 and 32 formed on the peripheral edge of the metal plate storage recess 26 can reliably protrude inward of the metal plate storage recess 26, and reliably protrude above the mounting piece 30 of the metal plate 25. Can be done.

In the method of the present invention, the ultrasonic vibration applied to the disk substrate 22 is a transverse vibration that vibrates in a direction parallel to the main surface 22a of the disk substrate 22.
The propagation in the thickness direction of the disk substrate 22 is small. Therefore, the heating on the inner side of the disk substrate 22 is controlled, and the inner deformation of the metal plate housing recess 26 is regulated. As a result, the thickness of the projecting pieces 31, 32 projecting inward from the metal plate housing recess 26 is controlled, and these projecting pieces 31, 32 are controlled.
Can be supported without being pressed against the mounting piece 30 of the metal plate 25. That is, the metal plate storage recess 2
6 is made deeper than the thickness of the metal plate 25 to maintain a gap w between the protruding pieces 31 and 32 and the mounting piece 30 as shown in FIG. Can be loosely fitted and held in the metal plate storage recess 26.

In this manner, the metal plate 25 is
6, the metal plate 25 can be prevented from being fixedly attached to the main surface of the disk substrate 22 by being inclined, and the heat of the disk substrate 22 made of synthetic resin and the metal plate 25 can be prevented. It is possible to prevent the disk substrate 22 from being deformed due to a difference in expansion coefficient.

As described above, the main surface 22a of the disk substrate 22
8 and 9 by symmetrically arranging projecting pieces 31 and 32 formed by applying ultrasonic vibration oscillating in a direction parallel to the direction of the periphery of the metal plate housing recess 26, for example, at four places. As shown, the metal plate 25 housed in the metal plate housing recess 26 is held by the disk substrate 2 with the mounting piece 30 supported by the plurality of projecting pieces 31 and 32.

By the way, the disk substrate 2 made of a polycarbonate resin and to which the method of the present invention is applied.
The ultrasonic vibration applied to 2 is from 15 KHz to 50 KH
It is set in the range of z. That is, if the vibration frequency is 15 KHz or less, it is difficult to obtain sufficient heat generation,
If the frequency is higher than 50 KHz, heat generation is remarkable,
This is because it is difficult to control the softening amount of the part that is brought into contact with and softened. The applied ultrasonic vibration is desirably about 20 KHz.

In this embodiment, the projecting pieces 31,
As shown in FIG. 8, 32 are formed at equal intervals at four locations so as to be symmetrical about the periphery of the metal plate storage recess 26.
It suffices if the metal plate 25 is prevented from falling out of the metal plate storage recess 26 and is supported on the disk substrate 22.
What is necessary is just to form it in two or more appropriate places.

In the above-described embodiment, the first and second contact portions 113 and 114 that come into contact with the peripheral edge of the metal plate housing recess 26 are provided.
Vibrator 1 having the same shape and substantially the same size
12 is used. However, the transverse ultrasonic vibration that vibrates in the axial direction of the vibration applicator 112 has an amplitude that decreases from the distal end to the proximal end of the vibration applicator 112. For this reason, the amplitude width of the second contact portion 114 provided on the base end side cannot be sufficiently ensured, and the second contact portion 1
There is a possibility that the size of the projecting piece 32 formed by the protrusion 14 may be smaller than the projecting piece 31 formed by the first contact portion 113 on the distal end side in the amount of inward projection of the recess 26. There is.

If the size of the protruding piece 32 is not sufficiently ensured as described above, it is not possible to obtain a sufficient amount of the protruding piece 32 to protrude inward of the metal plate housing recess 26, and the inside of the metal plate housing recess 26 cannot be obtained. There is a possibility that the supporting piece 30 of the metal plate 25 housed and arranged in the storage device cannot be reliably supported.

Therefore, attenuation of the amplitude width generated from the distal end side to the proximal end side of the vibration applicator 112 is compensated, and the protrusion 31 substantially the same as the projecting piece 31 formed by the first contact portion 113 on the distal end side is compensated. In order to make it possible to form the projecting piece 32 with a guaranteed amount, the size of the second contact portion 114 on the proximal end side is made larger than that of the first contact portion 113. That is, the vibration applicator 1 which causes attenuation of the amplitude of the ultrasonic vibration.
The contact area of the second contact portion 114 formed on the base end side of the second contact portion 12 with the disk substrate 22 is made larger than that of the first contact portion 113 on the distal end side. By increasing the size of the protruding piece 32 formed by the second contact portion 114, the amount of protrusion into the metal plate housing concave portion 26 is guaranteed, and the mounting piece 30 of the metal plate 25 is surely secured. It allows for support.

As described above, in order to increase the contact area of the second contact portion 114 formed on the base end side of the vibration applying element 112, the second contact portion 114 is constituted by three auxiliary contact portions. As shown in FIG. 10, three auxiliary protruding pieces 32a, 32b and 32c are formed on the peripheral edge of the metal plate housing recess 26, and formed by a second contact portion 114 formed on the base end side of the vibration applying element 112. Metal plate storage recess 2 of projection 32
6 to compensate for the amount of protrusion. By compensating the amount of protrusion of the protruding piece 32 protruding into the metal plate housing recess 26 in this manner, reliable support of the mounting piece 30 of the metal plate 25 is realized.

As another method, the second contact portion 11
4 is made larger than the first contact portion 113 on the front end side, and the area in contact with the disk substrate 22 is increased, so that the metal plate storage recess 26 is formed as shown in FIG.
Protruding piece 31 formed by the first contact portion 113 on the periphery of
By forming a protruding piece 32 larger than that of the metal plate 2 and compensating for the amount of protrusion protruding into the metal plate housing concave portion 26, the metal plate 2
5 can be reliably supported.

In the present embodiment, the metal plate 25 held by the disk substrate 22 is formed in a concave shape with the mounting piece 30 provided on the periphery, but it is sufficient to be stored in the metal plate storage recess 26. It may be a flat disk with a size.

Furthermore, in the above-described embodiment, an example in which the present invention is applied to a magneto-optical disk has been described. However, an information signal recording disk having a disk substrate made of a synthetic resin and having a magnetic plate for magnet chucking is used. It is widely applicable.

[0059]

According to the method of the present invention, the ultrasonic vibration is applied to the main surface of the disk substrate around the periphery of the magnetic plate housing recess in which the magnetic plate is housed, and a part of the periphery of the magnetic plate housing recess is thermally deformed. The magnetic plate is protruded into the plate accommodating recess, and the projected portion supports the periphery of the magnetic plate and holds the magnetic plate in the magnetic plate accommodating recess. Protrusions for supporting the magnetic plate can be formed without generating projections or the like on the surface, the smoothness of the main surface of the disk substrate can be sufficiently maintained, and the molding accuracy of the disk substrate is not hindered.

The amount of thermal deformation of the peripheral edge of the magnetic plate housing recess can be easily controlled by controlling the ultrasonic vibration applied to the disk substrate, so that the magnetic plate can be accurately and easily held on the disk substrate. It becomes possible.

Also, by using ultrasonic vibration which vibrates in a direction parallel to the main surface of the disk substrate, deformation inside the disk substrate can be regulated, so that the magnetic plate provided in the metal plate housing recess is loosely fitted. Since the magnetic plate can be easily held, it can be prevented that the magnetic plate is fixedly attached to the main surface of the disk substrate by being inclined. Then, it is possible to prevent the deformation of the disk substrate caused by the difference in the coefficient of thermal expansion between the disk substrate made of a synthetic resin and the magnetic plate using a metal plate. The mechanism can be stably mounted on the disk table of the mechanism.

Further, since the disk substrate used in the method of the present invention does not need to form a projection for supporting the magnetic plate on the main surface, the configuration of the disk substrate is simplified, and a disk mold for molding the disk substrate is used. Processing becomes easy, and furthermore, molding of the disk substrate becomes easy. In particular, the mold for molding the disk substrate is simplified, and the molding of the disk substrate is facilitated, so that the molding distortion which causes the occurrence of birefringence or the like which deteriorates the optical characteristics of the molded disk substrate is reduced. Thus, an information signal recording disk having extremely good signal recording / reproducing characteristics without causing writing or reading defects of the information signal can be formed.

Further, at least two points of the contact portion on the distal end side and the contact portion on the base end side of the vibration applicator are brought into contact with the peripheral edge of the magnetic plate housing recess so as to apply ultrasonic vibration. Thus, since the two points are simultaneously thermally deformed, not only can the magnetic plate be quickly held, but also the configuration of the ultrasonic wave application device is simplified.

Furthermore, the contact area of the vibration applicator for thermally deforming the periphery of the magnetic plate housing recess with the disk substrate can be varied in accordance with the vibration characteristics of the applied ultrasonic wave. The amount of thermal deformation of the substrate is sufficiently compensated at any position of the vibration applying element,
The magnetic plate can be reliably held on the disk substrate.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a magneto-optical disk to which the method of the present invention is applied.

FIG. 2 is a sectional view showing a disk substrate and a metal plate constituting the magneto-optical disk.

FIG. 3 is a schematic sectional view showing a disk support table used in the method of the present invention.

FIG. 4 is a sectional view showing a state where a disk substrate is mounted on the disk support table.

FIG. 5 is a sectional view showing a state in which a metal plate is housed and arranged in a metal plate housing recess of a disk substrate to which the method of the present invention is applied.

FIG. 6 is a cross-sectional view showing a state in which a vibration applicator of an ultrasonic wave application device is brought into contact with a peripheral edge of a magnetic plate housing concave portion of a disk substrate.

FIG. 7 is a cross-sectional view showing a state in which a protruding piece is formed by applying ultrasonic vibration to the periphery of the magnetic plate storage recess of the disk substrate.

FIG. 8 is a plan view of a magneto-optical disk to which a metal plate made of a magnetic material is attached according to the method of the present invention.

FIG. 9 is a cross-sectional view showing a state where a magnetic metal plate is attached to the disk substrate.

FIG. 10 is a plan view of a magneto-optical disk showing another example in which a magnetic metal plate is attached to a disk substrate by the method of the present invention.

FIG. 11 is a plan view of a magneto-optical disk showing still another example in which a metal plate made of a magnetic material is mounted on a disk substrate according to the method of the present invention.

FIG. 12 is a sectional view of a magneto-optical disk in which a metal plate is mounted on a disk substrate by a conventional method.

FIG. 13 is an exploded perspective view of a magneto-optical disk applied to another conventional method.

FIG. 14 is a sectional view of a magneto-optical disk in which a metal plate is mounted on a disk substrate by another conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Magneto-optical disk 22 Disk substrate 23 Center hole 25 Metal plate 26 Metal plate accommodation concave part 31, 32 Projection piece 112 Vibration applicator of ultrasonic wave applying device 113 First contact part 114 Second contact part

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-307853 (JP, A) JP-A-5-325468 (JP, A) Radio technology, Vol. 45, No. 12, December 1991 ) Pp. 152-155 (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 24-7/26 G11B 11/105 G11B 23/00

Claims (2)

(57) [Claims] 1. A magnetic disk formed around a center hole on one main surface side of a disk substrate made of a synthetic resin having a center hole formed therein and an information signal recording layer formed on one main surface side. In holding the magnetic plate in the plate storage recess, at least two points of the contact portion on the distal end side and the contact portion on the base end side of the vibration applicator are brought into contact with the periphery of the magnetic plate storage recess to apply ultrasonic vibration, A method of holding a magnetic plate with respect to a disk substrate, wherein at least a part of a peripheral edge of the magnetic plate storage recess is thermally deformed to hold the magnetic plate in the magnetic plate storage recess. 2. The method for holding a magnetic plate on a disk substrate according to claim 1, wherein the vibration applying element has a larger contact area of the contact portion on the base end side with the disk substrate than the contact portion on the distal end side. .