JP3200982B2 - 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 a disk for recording an information signal, such as an optical disk or a magneto-optical disk, on which a desired information signal is recorded. Related to a disc to be chucked.

[0002]

2. Description of the Related Art Hitherto, as an information signal recording disk on which a desired information signal is recorded, an optical disk or a magneto-optical disk which records or reproduces an information signal using a light beam has been proposed. As an optical disc including a magneto-optical disc for recording or reproducing an information signal using this light beam, an optical disc capable of recording information signals at high density and having a very small diameter has been proposed. As this type of optical disk, a small-diameter optical disk having a diameter of, for example, 64 mm or less has been proposed.

An optical disk having such a small diameter and capable of high-density recording is mounted on a disk rotation drive mechanism and rotated at a high speed. Then, in a state of being rotated at a high speed, an information signal is reproduced by irradiating a recording track provided on a signal recording layer formed on one main surface of the optical disk with a light beam emitted from an optical pickup. In an optical disk capable of recording an information signal, the recording track is irradiated with a light beam emitted from an optical pickup and a magnetic head applies an external magnetic field to record the desired information signal. Is performed.

In order to accurately read information signals recorded on recording tracks formed at high density on a small-diameter optical disk which is rotated at a high speed, or to record information signals accurately on the recording tracks. It is necessary to accurately irradiate the recording track with a light beam. In order to accurately irradiate a light beam to a recording track formed at a high density on a small-diameter optical disk, the optical disk is surely integrated with a disk table of a disk rotation drive mechanism and the disk table is It is necessary that positioning be achieved with high precision and that the rotating operation be performed in precise synchronization with the disk table.

Therefore, in order to reliably integrate the optical disk with the disk table, and to position and mount the optical disk with high precision on the disk table, a metal plate which is a chucking magnetic plate disposed at the center of the optical disk is mounted. There is proposed a disk mounting method in which the optical disk is magnetically attracted by a magnet arranged on the disk table while the optical disk is mounted on the disk table, and the optical disk is mounted on the disk table.

As shown in FIGS. 5 and 6, a small-diameter optical disk 1 used in a disk mounting system utilizing the attractive force of a magnet is formed by molding a transparent synthetic resin such as a polycarbonate resin into a disk shape. Disc substrate 2
A recess 5 is formed on one main surface 2a side around a center hole 3 formed in the center of the disk substrate 2,
A metal plate 6 for magnetic attraction is arranged in the recess 5.

The small-diameter optical disk 1 having a diameter of 64 mm or less is formed such that the thickness of the disk substrate 2 at a portion where a signal recording area is formed is as thin as about 1.2 mm. When the thickness of the disk substrate 2 is small, the center hole 3 is also shallow in accordance with the thickness of the disk substrate 2.

The center hole 3 is provided on the disk table 12 side when the optical disk 1 is mounted on the disk table 12 of a disk rotation drive mechanism 11 having a drive motor 10 as shown in FIG. The centering member 13 has a function of centering the optical disk 1 with respect to the disk table 12 by engaging the centering member 13.

The centering member 13 disposed on the disk table 12 side is
Is mounted on the distal end of the rotary drive shaft 14 while being urged by a coil spring 15. The centering member 13 is used to move the optical disc 1 from the disc table 12.
When the optical disk 1 is mounted on the optical disk 1, the optical disk 1 engages with the center hole 3 while moving forward and backward in the axial direction of the rotary drive shaft 14 against the urging force of the coil spring 15 under the load of the optical disk 1. Is centered on the disk table 12.

In order to mount the optical disk 1 on the disk table 12 with the centering member 13 configured as described above, the height of the centering member 13 is not sufficiently large, and the optical disk 1 and the centering member It is necessary to increase the relative movement amount with respect to.

Therefore, in this type of optical disk 1, as shown in FIG. 6, the other main surface 2a of the disk substrate 2 opposing the one main surface 2a on which the metal plate 6 is disposed.
In FIG. 2B, a ring-shaped bulging portion 7 is provided so as to surround the center hole 3 so that the depth of the center hole 3 is made sufficiently large. By providing the bulging portion 7 in this manner, the height of the centering member 13 which is relatively engaged with the center hole 3 is made sufficiently large. The amount of relative movement of the member 13 can be increased, and the mounting of the optical disk 1 in which the centering is assured is realized.

When the bulging portion 7 is provided on the disk substrate 2 as described above, the portion provided with the bulging portion 7 becomes partially thick. If the disk substrate 2 is formed using a synthetic resin such as a polycarbonate resin, it becomes extremely difficult to uniformly cure the entire disk substrate 2 if the disk substrate 2 is formed using a synthetic resin such as a polycarbonate resin. In particular, the thickened bulging portion 7 has a lower curing speed than the thinner portion where the signal recording area is formed, so that so-called sink marks, which are molding distortions, are likely to occur. Further, the distal end surface of the bulging portion 7 is attached to the mounting reference surface 7a with respect to the disk table 12.
In the optical disk 1, the mounting reference surface 7a does not become a smooth surface if the bulging portion 7 has sink marks. If the smoothness of the mounting reference surface 7a is not maintained, the optical disk 1 cannot be mounted on the disk mounting surface 12a of the disk table 12 while maintaining accurate horizontality. The signal recording surface cannot be made orthogonal to the optical axis of the light beam emitted from the head accurately. Then, the light beam cannot accurately track the recording track of the optical disc 1, and the recording and reproduction of the information signal cannot be performed with good recording and reproduction characteristics.

Accordingly, the applicant of the present application has proposed that one main surface 2a of the disk substrate 2 opposes the side where the bulging portion 7 protrudes.
The depth of the concave portion 5 formed on the side is adjusted so that the thickness of the portion forming the bulging portion 7 is substantially equal to the thickness of the main portion of the disk substrate 2 where the signal recording area is formed. An optical disk 1 configured as follows is proposed. By making the entire disk substrate 2 to have a substantially uniform thickness including the portion constituting the bulging portion 7 as described above, when the disk substrate 2 is molded using a synthetic resin material, the bulging portion 7 is included. It is possible to cure the entire disk substrate 2 uniformly,
The disk table 1 has a mounting reference surface 7a in which the occurrence of sink marks or the like as molding distortion is suppressed and the smoothness is maintained with high accuracy.
2, the optical disk 1 can be mounted while maintaining the horizontal level accurately, and is rotated in synchronization with the disk table 12 accurately, so that it is possible to form the optical disk 1 which can guarantee good recording and reproducing characteristics.

In the disk substrate 2 described above, the thickness T ₁ of the portion forming the bulging portion 7 is substantially equal to the thickness T ₂ of the main portion of the disk substrate 2 where the signal recording area is formed. Since the depth of the concave portion 5 is adjusted to have the same thickness, the concave portion 5 has a depth D ₁ substantially equal to the thickness of the main portion of the disk substrate 2. Therefore, if a metal plate simply formed in a flat disk shape is disposed in the recess 5, the center hole 3 is closed at an intermediate portion, and the depth of the center hole 3 is reduced.

Therefore, the metal plate 6 disposed on the optical disk 1 constituted by using the disk substrate 2 has a rising portion 6b formed by bending on the outer peripheral portion side. The main surface portion 6a at the center corresponding to the center hole 3 is configured to be flush with one main surface 2a of the disk substrate 2. A concave portion 5 parallel to the main surface portion 6a is provided on the outer peripheral edge of the rising portion 6b.
A mounting piece 6c is formed on the mounting surface 5a. The metal plate 6 configured as described above is placed in the concave portion 5 as shown in FIG. 6 so that the mounting piece 6c is mounted on the mounting surface 5a of the concave portion 5. At this time, the upper metal plate 6 is attached to the disk substrate 2 by joining the mounting piece 6c to the mounting surface 5a with an adhesive.

[0016]

[SUMMARY OF THE INVENTION] As described above, the thickness T ₁ of the portions constituting the swelling portion 7 is substantially equal to the thickness of the main portion of the signal recording region of the disc substrate 2 is formed Since the depth D ₁ of the concave portion 5 is adjusted to be the thickness T ₂ , the thickness W ₁ of the connecting portion of the bulging portion 7 to the disk substrate 2 is equal to the thickness of the main portion of the disk substrate 2. It has been made as approximately equal to T ₂ is. At this time, the rising peripheral wall 5b is formed steeply rising with respect to the mounting surface 5a on the bottom side of the concave portion 5, and the corner portion 5c where the mounting surface 5a and the rising surface 5b are continuous as shown in FIG. With the acute angle, when an external force is applied to the disk substrate 2, the internal stress tends to concentrate on the corner portion 5c, and there is a possibility that the disk substrate 2 may be easily broken.

In order to prevent concentration of internal stress on the corner portion 5c where the mounting surface 5a and the rising surface 5b of the recess 5 are continuous, as shown in FIG. 8, the corner portion 5c is gently curved. It can be considered as a plane.

On the other hand, the metal plate 6 is disposed in the concave portion 5 without causing a large positional deviation, and is attached to the concave portion 5 in a stable state. They are formed with substantially equal outer diameters. Therefore, as shown in FIG.
There is a possibility that the mounting piece 6c may be fixedly disposed in the concave portion 5 while riding on the corner portion 5c having a gentle curved surface. As a result, the metal plate 6 cannot be mounted parallel to the main surface 2 a of the disk substrate 2, and the height from the mounting reference surface 7 a to the disk table 12 on the tip side of the bulging portion 7 to the main surface 6 a of the metal plate 6. The accuracy of the height H ₁ (see FIG. 6) is not constant. That is, the centering member 13
Therefore, the depth of the center hole 3 with which the centering member 13 engages becomes shallow, and a sufficient amount of engagement of the centering member 13 cannot be guaranteed.

Therefore, the present invention suppresses the occurrence of a portion where internal stress is concentrated when a concave portion is formed in a disk substrate, guarantees the strength of the disk substrate, and accurately and stably holds the disk substrate in the concave portion. It has been proposed for the purpose of providing a disk for recording information signals, such as an optical disk, in which a plate for magnetic attraction such as a metal plate can be disposed.

[0020]

According to the present invention, there is provided a disc for recording an information signal which has a plate for magnetic attraction, such as a metal plate, and a center hole at a central portion in order to achieve the above-mentioned object. A disk substrate made of a synthetic resin in which a concave portion in which the plate is provided is formed on one main surface side surrounding the center hole, and a mounting surface of the plate is formed on a bottom surface side of the concave portion of the disk substrate. In addition, a curved portion having a depth that is lower than the mounting surface described above is formed in a portion where the mounting surface and the rising surface of the concave portion are continuous.

[0021]

The disk for recording information signals according to the present invention has a plate for magnetic attraction disposed in a recess formed around a center hole on one main surface side of a disk substrate. The curved portion having a depth that is lower than the mounting surface provided on the portion where the mounting surface and the rising surface are continuous is prevented from climbing to a corner portion where the mounting surface and the rising surface are continuous. It is mounted on the mounting surface described above.

[0022]

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

An optical disk 21 to which the present invention is applied is, as shown in FIGS. 1 and 2, a disk substrate 2 formed by molding a synthetic resin such as a polycarbonate resin into a disk shape.
2 is provided. One main surface 2 of the disk substrate 22
On the 2a side, an information signal recording layer for recording a desired information signal is formed. The optical disk 21 constituted by using the disk substrate 22
The other main surface 22b opposite to the one main surface 22a on which the information signal recording layer is formed is an information signal writing / reading surface, and the signal recording layer is irradiated with a light beam from the writing / reading surface side. Thus, recording and reproduction of the information signal are performed.

In the disk substrate 22 constituting the small optical disk 21 having a diameter R of 64 mm,
It becomes formed with a thickness T ₃ of 1.2 mm. Also,
In the optical disc 21, the inner diameter is 32 mm.
A signal recording area portion D on which an information signal is recorded has an outer peripheral side portion excluding the region of.

In the center of the disk substrate 22, the disk rotation driving device 1 having the above-described structure is provided.
A center hole 23 is formed in which a centering member 13 disposed on one disc table 12 side is engaged.
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.

Further, on the other main surface 22b side of the disk substrate 22, an annular bulging portion 24 is formed so as to surround the center hole 23 in a non-signal recording region E not formed as the signal recording region D. Are integrally formed.
The bulging portion 24 is formed by increasing the depth of the center hole 23 formed in the thin disk substrate 32 so that the centering member 13 disposed on the disk table 12 side can be formed.
The protrusion amount from the center hole 23 can be increased. That is, the bulging portion 24
Makes it possible to make the height of the centering member 13 engaged with the center hole 23 sufficiently large, and when the optical disk 21 is mounted on the disk table 12, the relative movement amount of the optical disk 21 and the centering member 13 is increased. And a centering operation for mounting the optical disk 21 with the rotation center of the optical disk 21 being aligned with the axis of the disk table 12 is ensured.

[0027] The bulging portion 24, the signal recording area of the disk substrate 22 is protruded with a thickness T ₃ and substantially the same projection height H ₂ of the configured main body portion, the disk table 12 and the distal end surface Mounting reference surface 24 to disk mounting surface 12a
a.

Further, an annular concave portion is provided on one main surface 22a side of the disk substrate 22 so as to surround the center hole 23 and accommodate a metal plate 25 which is a plate for magnetic attraction. 26 are formed. The recess 26 is a smaller diameter than the outside diameter r of the bulged portion 24 becomes formed in a substantially equal depth D ₂ to the thickness T ₃ of the main body portion of the disk substrate 22.

By forming a concave portion 26 for accommodating a metal plate having a depth substantially equal to the thickness T ₃ of the disk substrate 22 corresponding to the position where the bulging portion 24 is provided, the disk substrate 22 is formed. the thickness T ₃ and the thickness T ₄ of the bulging portion 24 which projects with a substantially same projecting height H _2, the thickness T ₃ of the disc substrate 22, that is, the signal recording area unit D formed part of the Is made equal to the thickness of

A step 28 is formed on the inner peripheral side of the bottom surface of the concave portion 26 serving as the mounting surface 27 of the metal plate 25. The step 28 prevents the formation of projections such as burrs on the mounting surface 27 of the metal plate 25 when the recess 26 is formed, and maintains the mounting surface 27 as a smooth surface. Things.

On the other hand, the metal plate 25 housed and disposed in the concave portion 26 is made of stainless steel having a thin thickness of about 0.4 mm without increasing the weight of the optical disc 21 and considering workability. It is formed by punching a metal material such as a plate (SUS-430) into a disk shape.

As shown in FIG. 1, the metal plate 25 is formed in a disk shape having an outer diameter substantially equal to or slightly smaller than the inner diameter of the recess 26 which is sufficient to be accommodated in the recess 26. is there. The center of the metal plate 25 is centered on the disk substrate 2.
A positioning hole 29 for positioning so as to be accommodated and disposed in the concave portion 26 so as to coincide with the center of 2 is formed.
The positioning hole 29 also functions as a jig insertion hole for holding the metal plate 25 when the metal plate 25 is housed and disposed in the recess 26.

When the metal plate 25 is simply formed into a flat disk shape, the metal plate 25 is housed and disposed in a concave portion 26 having a depth D ₂ substantially equal to the thickness T ₃ of the disk substrate 22. At this time, the depth of the center hole 23 formed at the center of the concave portion 26 is reduced.

In view of this, the metal plate 25 used in the present invention has a rising portion 30 formed by bending on the outer peripheral side. The rising portion 30 is formed to have such a height that the central main surface portion 25 a is flush with one main surface 22 a of the disk substrate 22 when the metal plate 25 is housed in the concave portion 26. A mounting piece 31 on a mounting surface 27 in the concave portion 26 is formed on the outer peripheral edge side of the rising portion 30 so as to be parallel to the main surface portion 25a. That is, as shown in FIG. 1, the metal plate 25 is formed in a disk shape having a concave shape as a whole.

The metal plate 25 formed as described above
As shown in FIG. 2, the mounting piece 31 is placed on the mounting surface 27 of the recess 26 and is housed in the recess 26. Then, the metal plate 25 is fixed in the concave portion 26 by joining the mounting piece 31 to the mounting surface 27 using an adhesive, and is attached to the disk substrate 22.

The fixing of the metal plate 25 in the concave portion 26 is not only performed by bonding using an adhesive, but also, as shown in FIG. The metal plate 25 may be supported by the support projections 32 and attached to the disk substrate 22.

By the way, the mounting surface 27 on which the mounting piece 31 of the metal plate 25 is mounted in the concave portion 26 in which the metal plate 25 of the disk substrate 22 constituting the present invention is housed and arranged, and the concave portion 26 As shown in FIG. 4, a groove-shaped curved portion 36 having a depth lower than the mounting surface 27 is formed at a portion corresponding to a corner portion where the rising surface 35 that is the peripheral surface is continuous. The curved portion 36 is provided in the concave portion 2.
6 is formed over the entire periphery of a portion corresponding to the corner portion.

As shown in FIG. 4, the curved portion 36 is formed as a groove having a substantially U-shaped cross section having circular arc portions 36a and 36b having a constant curvature on both sides. Then, the bending portion 36 is formed by formed with a depth D ₃ than the height of the arcuate portion 36a which is formed on the rising surface 35 surface side. That is, the rising surface 3 above the mounting surface 27
5 is a surface perpendicular to the mounting surface 27 described above.

By forming such a curved surface 36 in a portion where the mounting surface 27 and the rising surface 35 in the concave portion 26 are continuous, when the metal plate 25 is housed and arranged in the concave portion 26, The mounting piece 31 of the plate 25 is supported on the mounting surface 27 without riding on the rising surface 35 side. Therefore, the metal plate 25 is
Major surface 22a made parallel to the bulged portion 24 of the tip disc table 12 the recess 2 the accuracy of the height H ₃ extending in the main surface portion 25a from the mounting reference surface 24a forms constant to the
6 can be housed and arranged.

Further, by forming the curved portion 36 as described above in a portion where the mounting surface 27 and the rising surface 35 in the concave portion 26 are continuous, when an external force is applied to the disk substrate 21, Concentration of internal stress on a portion where the writing surface 27 and the rising surface 35 are continuous is avoided, and the strength of the disk substrate 22 is guaranteed.

In the above-described embodiment, an example in which the present invention is applied to an optical disk has been described. However, a disk provided with a synthetic resin disk substrate and having a concave portion on which a magnetic attraction plate is provided is formed on the disk substrate. By applying
The same functions and effects as those of the above embodiment can be realized.

[0042]

As described above, the information signal recording disk according to the present invention has a curved portion at the portion where the mounting surface and the rising surface in the recess where the magnetic attraction plate is disposed are continuous. Since it is formed, concentration of internal stress on a portion where the mounting surface and the rising surface are continuous can be avoided, and the strength of the disk substrate having the concave portion can be sufficiently ensured. .

Further, since the curved portion is formed to have a depth which is lower than the mounting surface in the concave portion, the magnetic attraction plate is securely supported by the mounting surface, and the curved portion is formed in the concave portion. The plate can be prevented from being disposed at an angle in the recess,
It is possible to prevent an error in the depth of the center hole formed in the disk substrate.

In particular, when forming the bulging portion on the disk substrate as in the optical disk of the above-described embodiment, a metal plate is provided so that the bulging portion is equal in thickness to the main portion of the disk substrate. By forming the depth of the concave portion, even if the thickness of the connecting portion of the bulging portion to the disk substrate cannot be sufficiently taken, providing the curved portion as described above Since concentration of the internal stress on the connecting portion can be avoided, sufficient strength assurance of the disk substrate can be realized, so that a disk with extremely small molding accuracy can be formed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an optical disc according to the present invention.

FIG. 2 is a partially enlarged sectional view of the optical disc.

FIG. 3 is a partially enlarged sectional view showing another example of the optical disc according to the present invention.

FIG. 4 is a partially enlarged cross-sectional view showing a curved portion provided in a concave portion formed in a disk substrate constituting the optical disk according to the present invention.

FIG. 5 is a cross-sectional view showing a state where a conventional optical disk is clamped on a disk table.

FIG. 6 is a partially enlarged cross-sectional view of the conventional optical disk.

FIG. 7 is an enlarged sectional view showing a concave portion where a metal plate formed on a disk substrate constituting the above-mentioned conventional optical disk is provided.

FIG. 8 is an enlarged cross-sectional view showing another example of a concave portion in which a metal plate is provided.

[Explanation of symbols]

 Reference Signs List 21 optical disk 22 disk substrate 23 center hole 24 bulging portion 25 metal plate 26 concave portion 27 mounting surface 31 mounting plate of metal plate 35 rising surface of concave portion 36 curved portion

Claims (1)

(57) [Claims] 1. A disk substrate made of a synthetic resin having a plate for magnetic attraction, a center hole in a center portion, and a concave portion surrounding said center hole and having said plate disposed on one main surface side. A mounting surface of the plate is formed on the bottom surface side of the concave portion of the disk substrate, and a portion of the mounting surface and a rising surface of the concave portion continuing from the mounting surface, A disc for recording an information signal, the disc having a curved portion having the same.