JPH05303865A - Method for holding magnetic plate on disk substrate - Google Patents

Abstract

PURPOSE:To mold the disk substrate of a disk for information signal recording in such a manner that a magnetic plate can be easily mounted thereto, the disk substrate to be mounted with this magnetic plate is easily molded and the deterioration in the optical characteristics after the molding can be prevented. CONSTITUTION:Ultrasonic vibrations in the direction orthogonal with the main surface of the disk substrate 22 are impressed to the peripheral edge of a recessed part 26 for housing the magnetic plate, in which the magnetic plate 25 is housed, to thermally deform at least a part at the peripheral edge of the recessed part 26 for housing the magnetic plate and to project this part into the recessed part 26 for housing the magnetic plate, by that, the peripheral edge of the magnetic plate 25 is supported.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention holds a magnetic plate disposed on a disk substrate which constitutes an information signal recording disk on which desired information signals are recorded, such as an optical disk or a magneto-optical disk. Regarding the method.

[0002]

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

The magneto-optical disk having such a small diameter and capable of high-density recording of information signals is mounted on a disk rotation driving device and rotated at a high speed. Then, while being driven to rotate 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 an optical pickup and a magnetic field head. A desired information signal is recorded by applying an external magnetic field that is magnetic field modulated according to the information signal to be recorded from an external magnetic field generator such as.

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

By the way, in order to surely integrate the magneto-optical disk into 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. A disk mounting method has been proposed in which the magneto-optical disk is chucked on the disk table by attracting the magnetic disk with a magnet arranged on the disk table side.

A magneto-optical disk 1 used in a magnet chucking system utilizing the attractive force of this magnet.
As shown in FIG. 10, the disk substrate 2 is formed by molding a synthetic resin such as a transparent polycarbonate resin into a disc shape. One main surface 2 of this disk substrate 2
An information signal recording layer on which a desired information signal is recorded is formed on the side a. Then, the disk substrate 2
Defines the other main surface 2b opposite to the one main surface 2a on which the information signal recording layer is formed as an information signal writing / reading surface, and irradiates the signal recording layer with a light beam from this writing / reading surface side. As a result, desired information signals are recorded or reproduced.

Further, in the central portion of the disc substrate 2,
As shown in FIG. 10, a center hole 3 with which a centering member arranged on the disk rotation drive side is engaged is formed. Further, one main surface 2 of the disk substrate 2
A metal plate 4, which is a magnetic plate, is disposed in the central portion on the a side so as to close the center hole 3. This metal plate 4
Is the center hole 3 on one main surface 2a side of the disk substrate 2.
It is arranged so as to fit into the metal plate accommodating recess 5 formed so as to surround it, and is joined to the disk substrate 2 with 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 metal plate is repeatedly mounted on and removed from the disk table of the disk rotation driving device. 4 may be easily peeled off from the disk substrate 2. That is,
This is because the load at the time of loading / unloading the disk table is applied to the joint portion of the metal plate 4 to the disk substrate 2, and the adhesive 6 is deteriorated.

In order to solve the problems caused by attaching the metal plate using such an adhesive, the applicant of the present application attaches the metal plate to the disc substrate without using the adhesive. Is proposed.
As shown in FIG. 11, this magneto-optical disk 11 has a center hole 13 surrounded by a main surface 12a on one side of which an information signal recording layer of a disk substrate 12 made of a synthetic resin such as transparent polycarbonate resin is adhered and formed. A metal plate accommodating recess 15 is formed so that the metal plate 14 is accommodated therein, and a caulking projection 16 of the metal plate 14 is provided on the outer peripheral edge side of the metal plate accommodating recess 15. A plurality of the convex portions 16 are provided at equal intervals on the outer peripheral edge side of the metal plate accommodating concave portion 15.

After the metal plate 14 is accommodated in the metal plate accommodating concave portion 15 and heat is applied to the convex portion 16, as shown in FIG.
As shown in FIG. 2, by thermally deforming the tip side of these convex portions 16 toward the metal plate accommodating concave portion 15 side, the metal plate 1 is projected by the support piece 16 a protruding from the tip of this convex portion 16.
4 is supported in the metal plate accommodating recess 15 and is attached to the disk substrate 12.

In the magneto-optical disk 11 in which the metal plate 14 is mounted by being supported by the supporting piece 16a protruding from the tip of the convex portion 16 integrally formed with the disk substrate 12 as described above, Since 14 is firmly supported by the disc substrate 12, even if the disc rotation driving device is repeatedly mounted on and removed from the disc table, it is possible to securely maintain the state of being attached to the disc substrate 12 without causing peeling or the like. Is 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 the mold for molding the disk substrate 12 becomes complicated. , It becomes difficult to process the mold.

When the convex portions 16 are formed intermittently on the outer peripheral edge side of the metal plate accommodating concave portion 15, the disk substrate 12
When molding, the flow of the synthetic resin material melted in the portion where the convex portion 16 is formed is not uniform, further, the curing time of the synthetic resin material is displaced, and so-called weld lines are generated. There is a risk that the uniformly cured disc substrate 12 may not be molded. Further, if the disk substrate 12 is not uniformly hardened, internal stress remains in the disk substrate 12, causing birefringence and the like in the disk substrate 12 and deteriorating the optical characteristics. In particular, if birefringence occurs in the disk substrate 12, writing or reading of an information signal will occur when it is configured as the magneto-optical disk 11.

Therefore, in order to solve the problem caused by intermittently forming the convex portions for supporting the metal plate as described above, a series of ring-shaped convex portions is formed on the outer peripheral edge side of the metal plate accommodating concave portion. A disk substrate adapted to be formed is conceivable. However, it is extremely difficult to perform crimping to support the metal plate arranged in the metal plate accommodating recess by uniformly deforming a series of ring-shaped protrusions by heat, and it is not feasible. Is.

It is also conceivable to partially heat-deform a part of a series of ring-shaped convex portions to carry out crimping so as to support the metal plate, but the metal plate was supported on the disk substrate. After that, the part that was not thermally deformed remains in a protruding shape. Therefore, the thickness of the disc substrate itself becomes thicker only in the above-mentioned protruding portion, and the magneto-optical disc constituted by using this disc substrate also becomes thicker. Then, it becomes difficult to design a disc cartridge for accommodating the magneto-optical disc. That is, since the disc cartridge can be used with versatility, its thickness is regulated to be constant.

Therefore, according to the present invention, the mold for molding the disk substrate can be easily processed, the disk substrate can be easily molded, the deterioration of the optical characteristics of the molded disk substrate can be prevented, and the birefringence can be prevented. A disk substrate that enables the molding of a disk substrate for an information signal recording disk that does not cause problems such as the above, maintains the smoothness of the main surface side of the disk substrate, and securely holds the magnetic plate on the disk substrate. It is an object of the present invention to provide a method for holding a magnetic plate against the above.

[0017]

In order to solve the above-mentioned problems and achieve the above-mentioned object, the present invention has a center hole and an information signal recording layer formed on one main surface side. In holding the magnetic plate in the magnetic plate storage recess formed by surrounding the center hole on one main surface side of the disk substrate made of synthetic resin, the periphery of the magnetic plate storage recess is perpendicular to the main surface of the disk substrate. By applying ultrasonic vibrations in the direction to heat and thermally deform at least a part of the peripheral edge of the magnetic plate housing recess, the magnetic plate is held in the magnetic plate housing recess.

[0018]

According to the method of the present invention, when ultrasonic vibration in the direction orthogonal to the main surface of the disk substrate is applied to the peripheral edge of the magnetic plate accommodating recess containing the magnetic plate, at least a part of the peripheral edge of the magnetic plate accommodating recess is thermally deformed. Then, the peripheral edge of the magnetic plate is supported by protruding into the magnetic plate accommodating recess, and the magnetic plate is held in the magnetic plate accommodating recess.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete 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 below 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 includes a disk substrate 22 formed by molding a synthetic resin material such as a polycarbonate resin having 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.
It is formed in a disk shape of mm.

A magneto-optical disk 21 constructed by using this disk substrate 22 is formed by depositing an information signal recording layer on the main surface 22a of the disk substrate 22 on which a desired information signal is recorded. A recording surface is provided and one main surface 2 on which the information signal recording layer of the disk substrate 22 is adhered and formed
The other main surface 22b opposite to 2a is used as an information signal writing / reading surface, and the information signal is recorded / reproduced by irradiating the signal recording layer with a light beam from this writing / reading surface side. Become.

As shown in FIGS. 1 and 2, in the central portion of the disk substrate 22 which constitutes the magneto-optical disk 21, as shown in FIGS.
A center hole 23 is formed to engage with a centering member arranged at the center of a disk table that constitutes a disk rotation driving device arranged in the recording / reproducing apparatus.
The center hole 23 is formed so as to penetrate the disk substrate 22, and is formed so that the center thereof coincides with the center of curvature of a recording track formed in the signal recording layer in a concentric or spiral shape.

Further, as shown in FIG. 2, an annular protrusion 24 is integrally formed around the center hole 23 at the center of the other main surface 22b of the disk substrate 22. .. The protrusion 24 is formed by deepening the depth of the center hole 23 formed in the thin disk substrate 22, so that the center hole of the centering member arranged on the side of the disk table on which the magneto-optical disk 21 is mounted. The protrusion amount with respect to 23 is increased, and the centering operation for 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 performed reliably. Further, the tip end surface of the protruding portion 24 functions as a mounting reference surface 24a for mounting on the disc table.

The projecting portion 24 is formed at least in the non-signal recording area on the inner peripheral side of the disk substrate 22 where the signal recording layer is not formed, and is formed with a projecting amount substantially equal to the thickness T of the disk substrate 22. Has been done. Therefore, the portion of the disc substrate 22 on which the protruding portion 24 is formed is twice as thick as the substrate body portion.

An annular metal plate is provided in the center of one of the main surfaces 22a of the disk substrate 22. A metal plate 25 that surrounds the center hole 23 and serves as a magnetic plate for attracting a magnet is disposed. A storage recess 26 is formed. The metal plate accommodating recess 26 has a diameter smaller than the outer peripheral diameter r of the protrusion 24 and is formed to a depth substantially equal to the thickness T of the disk substrate 22. In addition, the opening edge side of the metal plate storage recess 26 has a diameter larger than that of the inner portion, so that the metal plate 25 can be easily inserted into the metal plate storage recess 26.

As described above, the one main surface 22a side of the disk substrate 22 is a smooth surface only with the metal plate accommodating recess 26 formed therein.

Further, the metal plate 2 in the metal plate storage recess 26 is
A step portion 28 is formed on the inner peripheral side of the bottom surface portion that serves as the mounting surface 27 of No. 5. The step portion 28 prevents protrusions such as burrs from being generated on the mounting surface 27 of the metal plate 25 when the metal plate housing recess 26 is formed, and maintains the mounting surface 27 as a smooth surface. To do so.

On the other hand, the metal plate 25 accommodated and arranged in the metal plate accommodating recess 6 has a disk shape made of a magnetic metal material such as a stainless steel plate (SUS-430) having a thickness t of about 0.4 mm. It is formed by punching. As shown in FIG. 1, the metal plate 25 is formed in a disc shape having a size large enough to be housed in the metal plate housing recess 26, and is housed in the metal plate housing recess 26. When installed, the central main surface portion 25a is 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. In order to form the eggplant, a step bending process is applied to the outer peripheral edge side. That is, on the outer peripheral edge side of the metal plate 25, the mounting piece 30 on the mounting surface 27 is formed via the bent portion 29 that is 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 disc shape having a concave shape as a whole.

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

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 that the mounted disk substrate 22 can be positioned and suction-supported, and the support table main body 102.
As shown in FIG. 3, a disk substrate support table 103 for positioning and mounting the disk substrate 22 is provided on the upper surface side of the disk. The disc substrate support table 103 has a fitting protrusion 104 at its center, into which the center hole 23 of the disc substrate 22 fits, and the fitting protrusion 104.
A protrusion fitting recess 105 into which the protrusion 24 of the disk substrate 22 is fitted is provided on the outer periphery of the.

A protective sheet 106 having flexibility such as silicon rubber is attached to the disk substrate mounting surface side which receives the other main surface 22b side of the disk substrate 22 on which the disk substrate supporting table 103 is mounted. And so on. The protective sheet 106 is provided to prevent the other main surface 22b of the mounted disk substrate 22 from being damaged such as scratches.

Further, the suction support table 101 has
A suction mechanism is provided that vacuum-sucks and supports the disk substrate 22 placed on the disk substrate support table 103 using a vacuum air pump. This suction mechanism forms a plurality of suction ports 107 in the disc substrate support table 103 and forms a suction air chamber 108 by interposing an escutcheon 110 between the disc substrate support table 103 and the support table body 102. Room 10
8 is sucked by a vacuum air pump (not shown) through an air passage 109 formed in the support table main body 102 to suck and support the disc substrate 22 on the disc substrate support table 103.

The plurality of suction ports 107 are located at positions corresponding to the outer peripheral side and the center of the disk substrate 22 placed on the disk substrate support table 103, at positions corresponding to the central part, and at the protrusion fitting portion to which the protrusion 24 is fitted. Each of them is opened inside the fitting recess 105. By providing the suction ports 107 at such positions, the entire surface of the disk substrate 22 can be pressed evenly against the disk substrate support table 103 and supported.

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

As shown in FIG. 4, the disk substrate 22 is mounted on the suction support table 101 having the above-described structure with the metal plate accommodating concave portion 26 in which the metal plate 25 is disposed facing the upper surface side. To be done. At this time, the disk substrate 22
Fits the metal plate storage recess 26 into the center hole 23 and the projection 10
4 and the projection 24 is fitted into the projection fitting recess 105 to be mounted, whereby the positioning of the mounting position with respect to the suction support table 101 is achieved.

As described above, when the disk substrate 22 is mounted on the suction support table 101, the vacuum air pump is operated and air in the suction air chamber 108 is sucked through the air passage 109, so that the disk substrate 2 is sucked through the suction port 107.
The air between the suction support table 101 and the suction support table 101 is also sucked, and the disk substrate 22 is closely supported by the protective sheet 106 on the suction support table 101.

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 formed.
Since it is mounted on the suction support table 101,
Accurate positioning of the mounting position with respect to is achieved.

After the disk substrate 22 is mounted on the suction support table 101 in this way, 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 placing piece 10 is placed and placed on the placing surface 27 of the metal plate accommodating recess 26.

At the place where the metal plate 25 is accommodated in the metal plate accommodating recess 26, as shown in FIG. 6, the tip of the vibration applicator 112, which is a resonator of the ultrasonic wave applying device 111, is attached to the peripheral edge of the metal plate accommodating recess 26. , And ultrasonic vibration in a direction orthogonal to the main surface of the disk substrate 22 is applied. When applying ultrasonic vibration to the disk substrate 22, the vibration applicator 112 is used.
Are placed under a constant pressure on the disk substrate 22.

When ultrasonic vibration is applied in this manner, the peripheral portion of the metal plate accommodating recess 26 with which the vibration applicator 112 is in contact is heated and softened. At this time, the vibration applicator 112
Is pressed at a predetermined pressure, the metal plate storage recess 2
A recess 32 corresponding to the size of the vibration applicator 112 is formed on the peripheral edge of the metal plate 6 to accommodate the metal plate storage recess 2
A projecting piece 31 protruding toward the inner peripheral side of 6 is formed. This protrusion 3
As shown in FIG. 7, 1 projects onto the mounting piece 30 of the metal plate 25 housed and arranged in the metal plate housing recess 26, and supports the mounting piece 30.

By the way, since the ultrasonic vibration applied to the disk substrate 2 is so-called vertical vibration in the direction orthogonal to the main surface of the disk substrate 22, the vibration is propagated in the thickness direction of the disk substrate 22, The propagation of vibration in the direction of the main surface 22a of the disk substrate 22 is small. Therefore, the disk substrate 22 is mainly softened in the depth direction of the contact portion of the vibration applicator 112, and the main surface 22a.
Softening is restricted in the direction parallel to. Therefore, it is possible to accurately form the protrusion 31 having a size corresponding to the vibration applicator 112.

Protrusions 31 formed by applying ultrasonic vibration in a direction orthogonal to the main surface of the disk substrate 22 are symmetrically provided at several places, for example, four places, on the peripheral edge of the metal plate accommodating recess 26. As a result, as shown in FIGS. 8 and 9, 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.

The size of the vibration applicator 112 that contacts the peripheral portion of the metal plate accommodating recess 26 to form the protrusion 31 is set according to the size of the protrusion 31 to be formed.

By the way, a disk substrate 2 to which the method of the present invention formed by using a polycarbonate resin as a material is applied.
The ultrasonic vibration applied to 2 is 15 KHz to 40 KH
It is set in the range of z. That is, it is difficult to obtain sufficient heat at a vibration frequency of 15 KHz or less,
If the frequency is 40 KHz or more, heat is generated remarkably and the vibration applying element 112
This is because it becomes difficult to control the softening amount of the portion that is brought into contact with and softened. The ultrasonic vibration applied is preferably about 20 KHz.

Further, in this embodiment, the protruding piece 31
As shown in FIG. 9, four are formed at equal intervals on the periphery of the metal plate storage recess 26 so as to be symmetrical, but prevent the metal plate 25 from falling out of the metal plate storage recess 26. It suffices that the disc substrate 22 be supported, and it may be formed at two or more appropriate places.

Furthermore, the projection 31 may be formed over the entire circumference of the peripheral edge of the metal plate accommodating recess 26. When the protrusions 31 are formed on the entire circumference of the peripheral edge of the metal plate accommodating recess 26, the vibration applicator 112 is formed in a ring shape corresponding to the outer diameter of the metal plate accommodating recess 26. ..

In the present embodiment, the metal plate 25 held by the disk substrate 22 is formed in the shape of a recess having the mounting piece 30 on the periphery, but it can be stored in the metal plate storage recess 26. It may also be a flat disc having a size.

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

[0048]

According to the method of the present invention, ultrasonic vibration in a direction perpendicular to the main surface of the disk substrate is applied to the peripheral edge of the magnetic plate accommodating concave portion accommodating the magnetic plate, so that at least a part of the magnetic plate accommodating concave portion is surrounded. The magnetic plate of the disk substrate is disposed because it is thermally deformed to project into the recess for storing the magnetic plate, and the protruding portion supports the peripheral edge of the magnetic plate and holds it in the recess for storing the magnetic plate. The protrusions for supporting the magnetic plate can be formed without generating protrusions on the main surface of the disk substrate, the smoothness of the main surface of the disk substrate can be maintained sufficiently, and the molding accuracy of the disk substrate is hindered. There is no.

Since the amount of thermal deformation of the magnetic plate accommodating recess can be easily controlled by controlling the ultrasonic vibration applied to the disk substrate, the magnetic plate can be accurately and easily held on the disk substrate. It becomes possible.

Further, since the disk substrate used in the method of the present invention does not need to have protrusions for supporting the magnetic plate on the main surface, the structure of the disk substrate is simplified, and the mold for molding the disk substrate is simplified. Processing becomes easy, and the disk substrate can be easily formed. In particular, since the mold for molding the disk substrate is simplified and the molding of the disk substrate is facilitated, the molding distortion that causes the occurrence of birefringence or the like that deteriorates the optical characteristics of the disk substrate after molding is prevented. Thus, it is possible to configure an information signal recording disk having extremely good signal recording / reproducing characteristics that does not cause writing or reading failures of information signals.

[Brief description of 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 cross-sectional view showing a disk substrate and a metal plate that form 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 cross-sectional view showing a state where a disc substrate is mounted on the disc support table.

FIG. 5 is a cross-sectional view showing a state in which a metal plate is housed and disposed 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 where a vibration applicator of an ultrasonic wave application device is brought into contact with the peripheral edge of a magnetic plate housing recess of a disk substrate.

FIG. 7 is a cross-sectional view showing a state where a protrusion is formed by applying ultrasonic vibration to the peripheral edge of the magnetic plate housing recess of the disk substrate.

FIG. 8 is a cross-sectional view showing a state in which a metal plate that is a magnetic body is attached to the disc substrate.

FIG. 9 is a plan view of a magneto-optical disk to which a metal plate which is a magnetic material is attached by the method of the present invention.

FIG. 10 is a sectional view of a magneto-optical disk in which a metal plate is attached to a disk substrate by a conventional method.

FIG. 11 is an exploded perspective view of a magneto-optical disk applied to another conventional method.

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

[Explanation of symbols]

 21 Magneto-Optical Disk 22 Disk Substrate 23 Center Hole 25 Metal Plate 26 Metal Plate Storage Recess 31 Protrusion 112 Vibration Applicator of Ultrasonic Wave Applicator

Claims (1)

[Claims] 1. A magnetic material formed by surrounding a center hole on one main surface side of a disk substrate made of a synthetic resin having a center hole and an information signal recording layer formed on one main surface side. In holding the magnetic plate in the plate accommodating recess, ultrasonic vibration is applied to the peripheral edge of the magnetic plate accommodating recess in a direction orthogonal to the main surface of the disk substrate to thermally deform at least a part of the peripheral edge of the magnetic plate accommodating recess. A method for holding a magnetic plate on a disk substrate, wherein the magnetic plate is held in the recess for storing the magnetic plate.