JP3287004B2 - Disc for recording information signals - 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 on which a desired information signal is recorded, such as an optical disk or a magneto-optical disk.

[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,
It is necessary that the magneto-optical disk be surely integrated with the disk table of the disk rotation drive device, and that the rotation center be positioned with high precision on the axis of the disk table before mounting.

Further, as described above, high-density recording of information signals is made possible, and miniaturization of a recording and / or reproducing apparatus using an optical disk such as a magneto-optical disk having a small diameter as a recording medium is required. is there.

Accordingly, such a small-diameter optical disk is surely integrated with a disk table, positioned and mounted with high accuracy, and a recording and / or reproducing apparatus for recording and / or reproducing information signals on the optical disk. In order to achieve miniaturization, a magnetic plate for magnetic attraction such as a metal plate made of a magnetic material is disposed on the optical disk side, and the magnetic plate is attracted by a magnet disposed on the disk table side, and the optical disk is moved to the disk table. There has been proposed a disk mounting method employing a so-called magnet chucking method in which chucking is performed above.

As shown in FIG. 6, an optical disk 1 used in the magnet chucking system utilizing the attractive force of the magnet is a disk substrate formed by molding a synthetic resin material such as a transparent polycarbonate resin into a disk shape. 2
It has. 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 and formed is an information signal writing / reading surface, and light is written from the writing / reading surface side to the signal recording layer. By irradiating the beam, recording or reproduction of a desired information signal is performed.

As shown in FIG. 6, a center hole 3 is formed in the center of the disk substrate 2 to engage with a centering member provided on the disk rotation driving device. Further, a metal plate 4 which is a magnetic plate is disposed at a central portion on one main surface 2 a side of the disk substrate 2 so as to close the center hole 3. On the other main surface 2b of the disk substrate 2 opposite to the side on which the metal plate 4 is provided, a ring-shaped protrusion 6 having a smooth mounting reference surface 5 formed on the front end surface is provided in the center hole 3. It protrudes so as to surround it.

As shown in FIG. 7, the optical disk 1 constructed as described above is positioned and mounted on a disk table 8 of a disk rotation drive mechanism 7 provided on the recording and / or reproducing apparatus side. That is, the optical disk 1
The centering member 9 disposed on the disk table 8 side is engaged with the center hole 3, and the mounting reference surface 5 at the tip end of the protruding portion 6 is supported by the disk support surface 8 a of the disk table 8. Attached to. At this time, when the metal plate 4 is attracted by the magnet 10 disposed on the disk table 8 side, the center of the optical disk 1 coincides with the center of rotation of the disk table 8, and the mounting position is accurately positioned. It is integrated and mounted on the disk table 8.

[0010]

By the way, as shown in FIG. 6, the metal plate 4 of the optical disk 1 is attached to the disk substrate 2 by using an adhesive 11 or the like so as to be tightly fixed. In this way, the metal plate 4 is
If the metal substrate 4 and the disk substrate 2 made of a synthetic resin material have different linear expansion coefficients, the disk substrate 2 will be deformed such as warping due to a temperature change. Further, there is a possibility that internal stress is applied to a portion of the disk substrate 4 to which the metal plate 4 is bonded, thereby causing distortion, and causing birefringence when the light beam is irradiated.

As described above, when the disk substrate 2 is warped, when the light beam is irradiated to scan the recording track of the optical disk 1, the focus control and the tracking control of the light beam cannot be performed accurately. However, there is a possibility that recording and / or reproduction of the information signal cannot be performed. Also, when birefringence occurs in the disk substrate 2, there is a possibility that information signals cannot be recorded and / or reproduced in the same manner.

Therefore, the present invention provides a disk substrate which is free from warping or birefringence even when a magnetic plate such as a metal plate having a different linear expansion coefficient from the disk substrate is provided on the disk substrate. , Accurate information signal recording and / or
Alternatively, it has been proposed for the purpose of providing a disc for recording information signals that enables reproduction.

[0013]

According to the present invention, there is provided a disc for recording an information signal in which a center hole is formed and an information signal recording section is formed on at least one main surface in order to achieve the above-mentioned object. Formed on the other main surface, a disk substrate integrally formed with an annular protrusion surrounding the center hole, and a magnetic plate disposed at a central portion on one main surface side of the disk substrate. The magnetic plate has a diameter larger than the center hole and is formed in a disk shape covering the center hole, and the magnetic plate is separated from the disk substrate via a synthetic resin holding member. And by forming a recess in the center of one of the main surfaces of the disc substrate and disposing the magnetic plate and the holding member in the recess, the thickness of the disc substrate exceeds the thickness of the disc substrate. Not to be configured in thickness It is intended.

The concave portion in which the magnetic plate and the holding member are provided includes a magnetic plate storing concave portion for storing the magnetic plate, and a holding portion for storing the holding member provided on the outer peripheral side of the magnetic plate storing concave portion. The periphery of the member storage recess is formed in a step shape.

[0015]

In the information signal recording disk according to the present invention, when the disk substrate and the magnetic plate having different linear expansion coefficients expand and contract due to a temperature change, the disk substrate and the magnetic plate which are separated from each other affect each other. It expands and contracts without.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment in which the present invention is applied to an optical disk having a diameter of 64 mm will be described with reference to the drawings.

The optical disk 21 to which the present invention is applied is structured so that it is chucked to the disk rotation drive mechanism by the magnet chucking method in the same manner as the above-mentioned optical disk, and as shown in FIG. The disk substrate 22 is formed by molding a synthetic resin material such as a polycarbonate resin having transparency. The disk substrate 22 has a diameter R of about 64 mm and a thickness T of about 1.2 mm.

The magneto-optical disk 21 formed by using the disk substrate 22 has a signal signal recording layer on which a desired information signal is recorded on one of the main surfaces 22a of the disk substrate 22 to form a signal. A recording portion provided on one main surface 2 of the disk substrate 22 on which the information signal recording layer is formed;
The other main surface 22b opposite to 2a 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.

First, a description will be given of a magneto-optical disk 21 prior to the present invention. As shown in FIGS. A center hole 23 is formed for engaging a centering member provided at the center of a disk table constituting a disk rotation drive mechanism provided in the apparatus. This center hole 23 is
And is formed so that the center of the recording track formed concentrically or spirally on the signal recording layer coincides with the center of curvature.

As shown in FIGS. 1 and 2, an annular protruding portion 24 is formed integrally with the center surface of the disk substrate 22 on the other main surface 22b side so as to surround the center hole 23. Have been. 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 protrusion 2
4 is a reference surface 24a for mounting on a disk table.
Function as

One main surface 22a of the disk substrate 22
A metal plate 25 which is a magnetic plate is formed in a central portion on the side in a disk shape having a diameter larger than the diameter of the center hole 23 so as to cover the center hole 23. This metal plate 2
5 is held in a state of being separated from the disk substrate 22 by a holding member 26 attached to the one main surface 22a side of the disk substrate 22.

The holding member 26 for holding the metal plate 25 on the disk substrate 22 is made of the same synthetic resin material as that of the disk substrate 22 or a linear expansion approximating the synthetic resin material of the disk substrate 22. It is formed of a molded body of a synthetic resin material having a coefficient. Then, the holding member 26 has an outer diameter r ₁ from the somewhat s large-diameter inner peripheral diameter r ₂ of the metal plate 25, the thickness d ₁ of the metal plate 25 is substantially the same or somewhat s greater height h ₁ has a ring-shaped rising peripheral wall 27, and the rising peripheral wall 27
The metal plate 25 is provided with a falling-off prevention piece 28 protruding in the shape of a ring protruding inward from the upper end face of the metal plate 25.

The holding member 26 constructed as described above has a metal plate storage portion 29 sufficient to loosely hold the metal plate 25 on the inner peripheral side surrounded by the rising peripheral wall 27 and the falling-off preventing piece 28.
Is constituted.

As shown in FIG. 1, the holding member 26 is provided with a metal plate 25 disposed on one main surface 22a of the disk substrate 22 so as to cover the center hole 23. The metal plate 25 is attached to one of the main surfaces 22a of the disk substrate 22 by ultrasonic welding or the like with the leading end surface of the rising peripheral wall 27 as a bonding surface 27a. To be held.

The rising peripheral wall 27 of the holding member 26
Is the inner diameter r ₂ slightly larger than the outer diameter r ₁ of the metal plate 25.
Since being formed in a ring shape having a wall thickness d ₁ substantially equal or somewhat s large height h1 of the metal plate 25, the metal plate 25 is supported by the peripheral edge drop-off prevention piece 28 metal plate The metal plate storage portion 29 is loosely fitted to the metal plate storage portion 29 and prevented from falling off from the storage portion 29. That is, the metal plate 2
5 is held in a state of being released to the disk substrate 22 each have a gap w ₁ and w ₂ between the inner peripheral surface and between the one principal 25a and disengagement prevention piece 28 of the outer peripheral edge and the rising peripheral wall 27 Be done.

As described above, the metal plate 25 is connected to the disk substrate 2.
2 in a state where the metal plate 25 having a larger linear expansion coefficient than the disk substrate 22 made of a synthetic resin material elongates due to a temperature change under the use environment of the optical disk 21. also, since the difference in expansion amount can be absorbed by the gap w ₁ and w _2, it is prevented applied load, such as a deformation force to the disk substrate 22.

The gaps w ₁ and w ₂ are formed between the disk substrate 22 made of a synthetic resin material having a small coefficient of linear expansion and the metal plate 25 having a large coefficient of linear expansion due to a change in temperature under the use environment of the optical disk 21. The size is set so as to absorb the difference in the amount of elongation when mutually extended. Since the metal plate 25 made of a thin metal material has undergone a temperature change and the amount of extension in the thickness direction is relatively smaller than the amount of extension in the plane direction, the gap w in the thickness direction is small.
₂ is small enough. Therefore, by forming a rising peripheral wall 27 in the thickness d ₁ and substantially the same height h ₁ of the metal plate 25, eliminating the gap w2 in the thickness direction, falling-off preventing piece 28
In this case, the metal plate 25 may be brought into close contact with the disk substrate 22. By bringing the metal plate 25 into close contact with the disk substrate 22 by the drop-off preventing piece 28 in this manner, the metal plate 25 can be held on the disk substrate 22 without causing large backlash.

By the way, the holding member 26 is connected to the disk substrate 2.
In the case of using the ultrasonic welding method for joining to the substrate 2, the holding member 26 is desirably formed of the same material as the synthetic resin material constituting the disk substrate 22.
That is, in the case of joining by the ultrasonic welding method, the joining portion of the holding member 26 to the disk substrate 22 is melted and integrated with the disk substrate 22. This is because it is necessary to prevent the above-mentioned joint from being distorted when receiving the heat.

Further, in order to join the holding member 26 to the disk substrate 22, as shown in FIG. 3, a double-sided adhesive tape or a coating type adhesive 31 may be used. In this case, even if the holding member 26 and the disk substrate 22 expand with different expansion amounts due to the temperature change of the optical disk 21, the distortion caused by the difference in the expansion amount can be absorbed by the adhesive 31. , The holding member 26 is the disk substrate 22
May be formed of a synthetic resin material different from the material constituting the.

In the above example, the metal plate 25 is attached to the one main surface 22a of the disk substrate 22 by the holding member 2
The disk substrate 22 is stored and held in the disk substrate 22.
Is kept in a released state, but preferably,
As shown in FIG. 4, the disk substrate 22 is housed and held so that the disk substrate 22 is held free from the disk substrate 22.

That is, the optical disk 21 shown in FIG.
Is the periphery of one main surface 22a side of the center hole 23 of the disk substrate 22, the thickness of the metal plate 25 has an inner periphery diameter r ₃ of somewhat s diameter larger than the outside diameter r ₁ of the metal plate 25 d ₁ and the metal plate housing recess 3 having substantially the same or somewhat s large depth d ₂
2 is formed, and the metal plate 25 is loosely fitted and stored in the metal plate storage recess 32. A flat holding member 36 is provided on one main surface 22a of the disk substrate 22 so as to cover the metal plate 25, thereby preventing the metal plate 25 from dropping out of the metal plate storage recess 32. Disk substrate 22
In a state of being released.

Then, the metal plate storage recess 32 of the metal plate 25 is formed.
The plate-like holding member 36 for preventing falling off from the sheet is formed by punching a synthetic resin film sheet, and the outer peripheral side is joined to the disk substrate 22 by a double-sided adhesive tape or a coating type adhesive 37. Installed.
The flat holding member 36 is bonded only to the disk substrate 22 and is not bonded to the metal plate 25 in order to guarantee free expansion and contraction of the metal plate 25.

Further, a hole may be formed in the center of the flat holding member 36 as necessary.

By arranging the metal plate 25 so as to be housed in the disk substrate 22, the optical disk 21 can be configured without increasing the thickness.

According to the present invention, in order to configure the optical disk 21 within the thickness of the disk substrate 22, FIG.
As shown in FIG. 5, a joining recess 38 of the flat holding member 36 which is a recess for accommodating the flat holding member 36 is provided on the outer peripheral side of the metal plate housing recess 32, and the flat holding member 38 is provided in the joining recess 38. 36 are joined and arranged. That is, the metal plate housing recess 32 and the joining recess 38 are formed in a stepped shape as shown in FIG.

In the above-described embodiment, an example in which the present invention is applied to an optical disk has been described. However, the present invention can be widely applied to a magnetic chucking type information signal recording disk having a magnetic plate such as a metal plate. .

[0037]

As described above, in the information signal recording disk according to the present invention, the magnetic plate is held in a state of being separated from the disk substrate via the holding member. When a disk substrate and a magnetic plate having different linear expansion coefficients expand and contract, the disk substrate and the magnetic plate that are separated from each other can expand and contract without affecting each other. Recording and / or reproduction of various information signals.

Further, according to the present invention, a concave portion is formed in the central portion on one main surface side of the disk substrate, and a magnetic plate and a holding member are provided in the concave portion so that the thickness does not exceed the thickness of the disk substrate. With this configuration, the thickness of the disk itself can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an optical disk prior to the present invention, showing a state where a metal plate is held on a disk substrate.

FIG. 2 is an assembled perspective view of an optical disk prior to the present invention.

FIG. 3 is a cross-sectional view illustrating an example in which a holding member is bonded to a disk substrate with an adhesive.

FIG. 4 is a cross-sectional view showing another example of the optical disk prior to the present invention.

FIG. 5 is a sectional view showing an optical disk according to the present invention.

FIG. 6 is a cross-sectional view showing a conventional magnetic chucking type optical disk.

FIG. 7 is a cross-sectional view showing a state where a conventional magnetic chucking type optical disk is mounted on a disk rotation drive mechanism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 21 optical disk, 22 disk board, 23 center hole, 25 metal plate, 26 holding member, 32 metal plate storage recess, 36 flat holding member, 38 joining recess

Continuation of the front page (56) References JP-A-62-46446 (JP, A) JP-A-1-134772 (JP, A) Katsuaki Tsurushima, The features and prospects of the MD system discussed by the developers, radio technology, Japan , IAI Publishing Co., Ltd., December 1, 1991, December 1991, 152-156 Tadao Yoshida Kazuhiko Fujiya, Minidisk, realized by magneto-optical recording and data compression technology, Nikkei Electronics, Japan, Nikkei BP Shah, December 9, 1991, December 9, 1991, 160-168 (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 23/00 601 G11B 7/24 571

Claims (2)

(57) [Claims] 1. A center hole is formed, an information signal recording portion is formed on at least one main surface side, and an annular protrusion is integrally formed on the other main surface surrounding the center hole. A disk substrate; and a magnetic plate disposed at a central portion on one main surface side of the disk substrate, wherein the magnetic plate has a diameter larger than the center hole and is formed in a disk shape covering the center hole. The above magnetic plate is made of synthetic resin
Together it becomes so held in a state of being free with respect to the disc substrate through the manufacturing of the holding member, forming a recess in the center of one principal surface side of the disc substrate
And disposing the magnetic plate and the holding member in the recess.
The thickness should not exceed the thickness of the disk substrate.
A disc for recording an information signal, characterized in that: 2. The concave portion includes a magnetic plate storing concave portion that stores the magnetic plate and a holding member storing concave portion that stores the holding member provided on an outer peripheral side of the magnetic plate storing concave portion. 2. The information signal recording disk according to claim 1, wherein the information signal recording disk is formed on a disc.