JP2959208B2 - Information signal recording disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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. With respect to this type of disc, an extremely small-diameter disc capable of recording information signals at a high density has been proposed. For example, a small-diameter magneto-optical disk having a diameter of 64 mm or less has been proposed. Such a small-diameter magneto-optical disk capable of high-density recording is mounted on a disk rotation drive and rotated at 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 Thus, a desired information signal is recorded by applying an external magnetic field.

In order to precisely irradiate a fine recording track with a light beam while rotating at a high speed in this manner,
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.

In order to reliably 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 is used. Is attracted by a magnet arranged on the disk table side, and the magneto-optical disk is chucked on the disk table.

A magneto-optical disk 100 used in a disk chucking system utilizing the attraction of the magnet.
As shown in FIG. 7, a disk substrate 101 formed by molding a synthetic resin such as a transparent polycarbonate resin into a disk shape is provided. On one main surface 101a side of the disk substrate 101, an information signal recording layer for recording a desired information signal is formed. In the disk substrate 101, the other main surface 101b opposite to the one main surface 101a on which the information signal recording layer is formed is formed as an information signal writing / reading surface. By irradiating the layer with a light beam, information signals are recorded and reproduced.

As shown in FIG. 7, a center hole 102 is formed in the center of the disk substrate 101 to engage with a centering member provided on the disk rotation driving device. Further, the center hole 10 is formed at the center of the one main surface 101a side of the disk substrate 101.
A metal plate 103, which is a magnetic plate, is disposed so as to close block 2. The metal plate 103 is disposed on one main surface 101a side of the disk substrate 101 so as to be housed in a metal plate housing recess 104 formed so as to surround the center hole 102, and is provided with a double-sided adhesive tape, an adhesive 105, and the like. And is attached to the disk substrate 101 by bonding.

As described above, in the magneto-optical disk 100 in which the metal plate 103 is attached to the disk substrate 101 using the adhesive 105, the mounting and dismounting of the disk table of the disk rotation drive device is repeated. 103 may be easily separated from the disk substrate 101. That is, the load at the time of loading / unloading of the disk table is applied to the joining portion of the metal plate 103 to the disk substrate 101, and the adhesive 105 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. 8, the magneto-optical disk 200 surrounds a center hole 202 on one main surface 201a of a disk substrate 201 made of a synthetic resin such as a transparent polycarbonate resin on which an information signal recording layer is formed. A metal plate accommodating concave portion 204 is provided so as to accommodate the metal plate 203, and a convex portion 205 for caulking of the metal plate 203 is protruded from an outer peripheral side of the metal plate accommodating concave portion 204. The plurality of convex portions 205 are provided at equal intervals on the outer peripheral edge side of the metal plate housing concave portion 204.

After the metal plate 203 is accommodated in the metal plate accommodating concave portion 204, heat or ultrasonic waves are applied to the convex portion 205, and as shown in FIG.
5 is caulked toward the metal plate housing recess 204 side, so that the metal plate 203 is supported in the metal plate housing recess 204 by the tip end portion 205a of the caulked convex portion 205 and attached to the disk substrate 201. Things.

The tip 205a of the projection 205 formed integrally with the disk substrate 201 in this manner allows the metal plate 2
Magneto-optical disk 20 supported and mounted
0, since the metal plate 203 is firmly supported by the disk substrate 201, even if the disk rotation drive is repeatedly mounted on and dismounted from the disk table, the disk substrate 201 can be reliably removed without causing separation. Can be maintained.

[0011]

However, as described above, the protrusions 2 for supporting the metal plate 203 are provided on the disk substrate 201.
In order to form the disk substrate 05, the structure of a mold for molding the disk substrate 201 becomes complicated, and processing of the mold becomes difficult.

Further, the convex portion 205 is connected to the metal plate housing concave portion 204.
When the disk substrate 201 is formed, the flow of the synthetic resin melted in the portion where the convex portion 205 is formed becomes uneven when the disk substrate 201 is formed. In such a case, there is a possibility that a so-called weld line is generated, and a uniformly cured disk substrate 201 cannot be formed. If the disk substrate 201 is not cured uniformly, internal stress remains in the disk substrate 201 and the disk substrate 201 is hardened.
Degrades the optical characteristics of In particular, the disk substrate 2
When birefringence is generated in the optical disc 01 and the magneto-optical disc 200 is formed, the recording / reproducing characteristics of the information signal deteriorate.

As described above, in order to solve the problem caused by intermittently forming the convex portion for supporting the metal plate,
A disk substrate in which a series of ring-shaped convex portions are formed on the outer peripheral edge side of the metal plate housing concave portion is conceivable. However, it is extremely difficult to uniformly caulk a series of ring-shaped protrusions, and the feasibility is poor. Also,
It is conceivable to partially caulk a part of a series of ring-shaped convex portions, but even after the metal plate is supported on the disk substrate, portions that are not caulked 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 the optical characteristics of the molded disk substrate from deteriorating, and prevents birefringence. It has been proposed for the purpose of providing an information signal recording disk which does not cause any problem.

[0015]

In order to solve the above-mentioned problems and to achieve the above object, an information signal recording disk according to the present invention has a center hole formed therein and an information signal recorded on one main surface side. A disk substrate made of a synthetic resin having a signal recording layer formed thereon, and a magnetic plate disposed on one main surface side of the disk substrate to close the center hole,
By forming a magnetic plate storage recess in which the magnetic plate is disposed so as to surround the center hole on one main surface side of the disk substrate, and thermally deforming at least a part of the periphery of the magnetic plate storage recess. The magnetic plate provided in the magnetic plate storage recess is held by the disk substrate.

[0016]

In the information signal recording disk according to the present invention, a magnetic plate such as a metal plate made of a magnetic material is housed in a magnetic plate housing recess formed in a disk substrate, and the periphery of the magnetic plate housing recess is thermally deformed. Thus, the magnetic plate is attached to the disk substrate. For example, an ultrasonic swaging method is used for thermal deformation of the peripheral edge of the magnetic plate housing recess.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a magneto-optical disk 1 to which the present invention is applied includes a disk substrate 2 in which a synthetic resin such as a polycarbonate resin is formed in a disk shape. On one main surface 2a side of the disk substrate 2, an information signal recording layer on which a desired information signal is recorded is formed. In the disk substrate 2, the other main surface 2b opposite to the one main surface 2a on which the information signal recording layer is formed is formed as an information signal write / read surface, and the signal recording is performed from the write / read surface side. By irradiating the layer with a light beam, information signals are recorded and reproduced. The disk substrate 2 is formed with a thickness T of about 1.2 mm.

In the center of the upper disk substrate 2,
As shown in FIGS. 1 and 2, a center hole 3 is formed in which a centering member provided at the center of a disk table constituting a disk rotation driving device provided in the recording / reproducing apparatus engages. I have. The center hole 3 is formed so as to penetrate the disk substrate 2 and is formed so that its center coincides with the center of curvature of a recording track formed concentrically or spirally in the signal recording layer.

The other main surface 2 of the disk substrate 2
As shown in FIG. 2, an annular bulging portion 4 is formed integrally with the center portion of the b side so as to surround the center hole 3. The bulging portion 4 is formed by increasing the depth of the center hole 3 formed in the thin disk substrate 2 so that the centering member of the centering member disposed on the disk table side on which the magneto-optical disk 1 is mounted. The function is to ensure that the centering operation of mounting the magneto-optical disk 1 with the rotation center of the magneto-optical disk 1 aligned with the axis of the disk table is made small by making the amount of protrusion from the hole 3 large. It should be noted that the bulging portion 4 is provided at least with the disk substrate 2.
Is formed in a non-signal recording area where no signal recording layer is formed on the inner peripheral side, and is formed so as to have a protrusion amount substantially equal to the thickness T of the disk substrate 2. Therefore, the portion of the disk substrate 2 where the bulging portion 4 is formed is twice as thick as the substrate body.

In the center of the disk substrate 2 on one side of the main surface 2a, an annular metal plate housing recess 6 surrounding the center hole 3 and having a metal plate 5 as a magnetic plate disposed therein.
Are formed. The metal plate storage recess 6 has a diameter smaller than the outer diameter R of the bulging portion 4 and is formed at a depth substantially equal to the thickness T of the disk substrate 2. Also, the opening edge 6a side of the metal plate housing recess 6 is enlarged in diameter as compared with the inner portion,
The insertion of the metal plate 5 into the metal plate storage recess 6 is facilitated.

A step portion 8 is formed on the inner peripheral side of the bottom surface portion of the metal plate housing concave portion 6 serving as the mounting surface 7 of the metal plate 5. The step 8 prevents the formation of projections such as burrs on the mounting surface 7 of the metal plate 5 when the metal plate housing recess 6 is formed, and maintains the mounting surface 7 as a smooth surface. Is to do so.

On the other hand, the metal plate 5 housed and disposed in the metal plate housing recess 6 is formed by punching out 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. Formed. Then, the metal plate 5
As shown in FIG. 1, is formed in a disk shape large enough to be housed in the metal plate housing recess 6, and when housed in the metal plate housing recess 6, FIG. As shown in FIG. 5, the central main surface 5a is made flush with one main surface 2a of the disk substrate 2, and the inner peripheral surface 6a of the metal plate housing recess 6 faces the periphery of the metal plate 5. In order to achieve this, a step bending process is performed on the outer peripheral edge side. That is, the mounting piece 10 on the mounting surface 7 is formed on the outer peripheral edge side of the metal plate 5 via the bent portion 9 bent so as to hang down toward the peripheral edge. That is, as shown in FIG. 1, the metal plate 5 is formed in the shape of a disk having a concave shape as a whole.

The metal plate 5 formed as described above is placed such that the mounting piece 10 is mounted on the mounting surface 7 of the metal plate housing recess 6 as shown in FIG. It is housed and arranged in the recess 6. Here, as shown in FIG. 4, the protrusions 11 protruding into the metal plate housing recess 6 are obtained by thermally deforming several places, for example, four places, on the peripheral edge of the metal plate housing recess 6.
To form That is, these projections 11 crush and deform a part of the peripheral edge of the metal plate storage recess 6, and
This deformed part is formed so as to protrude into the metal plate housing recess 6. Therefore, on one main surface 2 a side of the disk substrate 2, the concave portion 1
No. 2 is formed only on the peripheral edge of the metal plate housing recess 6, and no projections such as projections are formed. Thus, the protrusion 1
1, the metal plate 5 is placed on the mounting piece 10
4 and 5 are supported by the projections 11 described above.
As shown in (1), it is housed and supported in the metal plate housing recess 6 and is fixed to the disk substrate 2. That is, as shown in FIG. 3, a step is formed on the peripheral edge of the metal plate 5 and the inner peripheral surface 6 a of the metal plate housing recess 6 is exposed. ing.

In this embodiment, the projection 11 is
As shown in FIG. 4, four portions are formed at equal intervals on the peripheral edge of the metal plate housing concave portion 6. However, if the disk substrate 2 is prevented from falling out of the metal plate housing concave portion 6 and is supported on the disk substrate 2. It may be formed at two or more appropriate places. Further, the protrusion 11 may be formed over the entire periphery of the metal plate housing recess 6.

In order to form the projections 11 by thermally deforming a part of the peripheral edge of the metal plate housing recess 6, for example, a heating iron is applied.

For the formation of the protrusions 11, a swaging method using ultrasonic waves is used. In this swaging method, as shown in FIG. 6, a contact 21 for applying an ultrasonic wave of an ultrasonic welding machine is brought into contact with the peripheral edge of the metal plate housing recess 6, and a portion contacted by the contact 21 is ultrasonically irradiated. The protrusions 11 are formed by projecting a part of the periphery of the metal plate housing recess 6 into the metal plate housing recess 6 by heat deformation.

In the above-described embodiment, an example in which the present invention is applied to a magneto-optical disk has been described. However, the present invention is widely applied to information signal recording disks having a disk substrate made of synthetic resin and having a magnetic plate such as a magnet chuck. Applicable.

[0028]

As described above, according to the present invention, a magnetic plate such as a metal plate made of a magnetic material is housed in a magnetic plate housing recess formed in a disk substrate, and the periphery of the magnetic plate housing recess is thermally deformed. By doing so, since the magnetic plate is attached to the disk substrate, it is not necessary to form a projection for supporting the magnetic plate on the disk substrate, so that the configuration of the disk substrate is simplified and the disk substrate The processing of the mold to be molded becomes easy, and the molding of the disk substrate also becomes easy. In particular, since the mold for molding the disk substrate is simplified and the molding of the disk substrate is facilitated, it is possible to prevent the occurrence of molding distortion such as birefringence which causes deterioration of the optical characteristics of the molded disk substrate. As a result, an information signal recording disk having extremely good signal recording / reproducing characteristics can be formed.

[0029]

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view showing a state in which a metal plate is housed and arranged in a metal plate housing recess of the disk substrate.

FIG. 4 is a cross-sectional view showing a state where a metal plate is attached to a disk substrate.

FIG. 5 is a plan view showing a mounting surface side of a metal plate of the magneto-optical disk according to the present invention.

FIG. 6 is a schematic side view showing a state where a metal plate is attached to a disk substrate by using a swaging method.

FIG. 7 is a sectional view of a conventional magneto-optical disk.

FIG. 8 is an exploded perspective view showing another example of a conventional magneto-optical disk.

FIG. 9 is a sectional view of the magneto-optical disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magneto-optical disk 2 ... Disk board 3 ... Center hole 5 ... Metal plate 6 ... Metal plate storage recess 11 ... Projection

Continuation of front page (56) References JP-A-1-208783 (JP, A) JP-A-1-208784 (JP, A) JP-A-2-118980 (JP, A) (58) Fields investigated (Int .Cl. ⁶ , DB name) G11B 7/24 571 G11B 23/00 601

Claims (1)

(57) [Claims] 1. A disk substrate made of a synthetic resin in which a center hole is formed and an information signal recording layer is formed on one main surface side, and one main surface of the disk substrate by closing the center hole. A magnetic plate disposed on one side of the disk substrate, and a magnetic plate receiving recess in which the magnetic plate is disposed surrounding the center hole on one main surface side of the disk substrate; An information signal recording disk wherein the magnetic plate provided in the magnetic plate housing recess is held by the disk substrate by thermally deforming at least a part of the periphery of the disk.