JPH064909A - Disk for information signal recording - Google Patents

Abstract

PURPOSE:To assure the strength of a disk substrate having a recessed part to be disposed with a plate for magnetic attraction and to exactly dispose the plate in a stable state into the recessed part. CONSTITUTION:This disk has a center hole 23 in the central part and has the disk substrate 22 consisting of a synthetic resin formed with the recessed part 26 disposed with the plate 25 for magnetic attraction on one main surface side enclosing this center hole 23. A curved part 36 having the depth recessing from an placing surface 27 is formed 10 the part of the recessed part 26 of the disk substrate 22 where the placing surface 27 on the base side and the rising surface 35 of the recessed part 26 are continuous.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc for recording an information signal such as an optical disc or a magneto-optical disc for recording a desired information signal, and more particularly to a disc table of a disc rotation drive mechanism utilizing magnetic attraction force. Discs that are chucked to.

[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 for recording or reproducing an information signal using a light beam has been proposed. An optical disc including a magneto-optical disc for recording or reproducing an information signal by using this light beam is capable of high density recording of an information signal, and has an extremely small diameter. For this type of optical disc, a small-diameter optical disc having a diameter of 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, the information signal is reproduced by irradiating the recording track provided on the signal recording layer formed on the one main surface of the optical disc with the light beam emitted from the optical pickup while being rotated at a high speed. In the case of an optical disk capable of recording an information signal, a desired information signal is recorded by irradiating the recording track with a light beam emitted from an optical pickup and applying an external magnetic field by a magnetic head. Is done.

In order to accurately read an information signal recorded on a recording track formed at a high density on a small-diameter optical disc that is rotated at a high speed, or to record an information signal accurately on the recording track. Therefore, it is necessary to accurately irradiate the recording track with the light beam. In order to accurately irradiate a recording beam formed with a high density on a small-diameter optical disc with a light beam, the optical disc is securely integrated with the disc table of the disc rotation drive mechanism, and Therefore, it is necessary to perform the positioning with high accuracy and to perform the rotational operation exactly in synchronization with the disk table.

Therefore, in order to surely integrate the optical disk into the disk table, and to position and mount the optical disk with high accuracy, the metal plate, which is a magnetic plate for chucking, disposed in the central portion of the optical disk. A disk mounting method has been proposed in which the above optical disk is magnetically attracted by a magnet disposed 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, the small-diameter optical disc 1 used in the disc mounting system utilizing the attractive force of the magnet is formed by molding a transparent synthetic resin such as polycarbonate resin into a disc shape. Disc board 2
And a recess 5 is formed on one main surface 2a side so as to surround the 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 disc 1 having a diameter of 64 mm or less is formed so that the thickness of the disc substrate 2 at the portion where the signal recording area is formed is as thin as about 1.2 mm. When the disk substrate 2 is thin as described above, the center hole 3 is also shallow corresponding to the thickness of the disk substrate 2.

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

By the way, the centering member 13 disposed on the disc table 12 side is the disc table 12
The rotary drive shaft 14 for supporting the rotary drive shaft 14 can be moved back and forth in the axial direction, and is attached to the tip end side of the rotary drive shaft 14 while being biased by the coil spring 15. The centering member 13 includes the optical disk 1 and the disk table 12
When the optical disc 1 is mounted on the optical disc 1, the optical disc 1 is engaged with the center hole 3 while advancing and retreating 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 disc 1. The centering of the disc table 12 is intended.

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

Therefore, in this type of optical disk 1, as shown in FIG. 6, one main surface 2a of the disk substrate 2 on which the metal plate 6 is disposed and the other main surface 2 opposite to the main surface 2a.
A ring-shaped bulging portion 7 is provided so as to surround the center hole 3 in b so as to make the depth of the center hole 3 sufficiently large. By providing the bulging portion 7 in this way, the height of the centering member 13 that relatively engages with the center hole 3 is made sufficiently large, and when the optical disk 1 is mounted on the disk table 12, the centering member 13 and the optical disk 1 are centered. The relative movement amount of the member 13 can be increased, and the optical disk 1 can be mounted with a reliable centering.

When the bulging portion 7 is provided on the disk substrate 2 as described above, the portion where the bulging portion 7 is provided becomes partially thick. Such a partially thick portion makes it extremely difficult to uniformly cure the entire disc substrate 2 when the disc substrate 2 is molded using a synthetic resin such as a polycarbonate resin. In particular, the thickened bulging portion 7 has a slower curing speed than the thin portion where the signal recording area portion is formed, so that a so-called sink mark which is a molding strain is likely to occur. Further, the tip end surface of the bulging portion 7 is attached to the disk table 12 as a reference surface 7a for mounting.
In the case of the optical disc 1, the mounting reference surface 7a does not become a smooth surface if the bulging portion 7 is sinked. If the smoothness of the mounting reference surface 7a is not maintained, the optical disc 1 cannot be mounted on the disc mounting surface 12a of the disc table 12 while maintaining the correct horizontality, and the optical disc 1 is rotated when the disc table 12 is rotated. The signal recording surface cannot be exactly orthogonal to the optical axis of the light beam emitted from the head. Then, the light beam cannot accurately track the recording track of the optical disc 1, and recording / reproducing of the information signal cannot be performed with good recording / reproducing characteristics.

Therefore, the applicant of the present application has found that one main surface 2a of the disk substrate 2 facing the side on which the bulging portion 7 is provided in a protruding manner.
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 disc substrate 2 in which the signal recording area portion is formed. An optical disc 1 configured as described above is proposed. By thus forming the entire disk substrate 2 to have a substantially uniform thickness including the portion forming the bulging portion 7, the bulging portion 7 is included when the disk substrate 2 is molded using a synthetic resin material. It becomes possible to cure the entire disk substrate 2 uniformly,
The disk table 1 has a mounting reference surface 7a that suppresses the occurrence of sink marks, which is a molding distortion, and maintains smoothness with high accuracy.
It is possible to form the optical disc 1 which can be mounted while accurately maintaining the levelness with respect to No. 2 and which is rotated in synchronization with the disc table 12 and which can ensure good recording and reproducing characteristics.

In the disk substrate 2 described above, the wall thickness T ₁ of the portion forming the bulging portion 7 is approximately equal to the wall thickness T ₂ of the main portion of the disk substrate 2 in which the signal recording area is formed. Since the depth of the recess 5 is adjusted so as to have the same thickness, the recess 5 has a depth D ₁ substantially equal to the thickness of the main body of the disk substrate 2. Therefore, if a metal plate 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, when the metal plate 6 provided on the optical disc 1 formed by using the disc substrate 2 has a rising portion 6b formed by bending on the outer peripheral side and is provided in the concave portion 5, The central main surface portion 6a corresponding to the center hole 3 is configured to be flush with the one main surface 2a of the disk substrate 2. In addition, at the outer peripheral edge of the rising portion 6b, the concave portion 5 that is parallel to the main surface portion 6a is formed.
A mounting piece 6c is formed on the inner mounting surface 5a. The metal plate 6 configured as described above is housed in the recess 5 as shown in FIG. 6 so that the mounting piece 6c is mounted on the mounting surface 5a of the recess 5. At this time, the upper metal plate 6 is attached to the disc substrate 2 by bonding the mounting piece 6c to the mounting surface 5a with an adhesive.

[0016]

By the way, as described above, the wall thickness T _{1 of the} portion forming the bulging portion 7 is substantially equal to the wall thickness of the main body portion of the disk substrate 2 where the signal recording area portion is formed. Since the depth D ₁ of the recess 5 is adjusted so as to be the thickness T ₂ , the thickness W ₁ of the connecting portion of the bulging portion 7 to the disc substrate 2 is the thickness of the main portion of the disc substrate 2. Is approximately equal to T ₂ . At this time, the rising peripheral wall 5b is formed so as to rise steeply with respect to the mounting surface 5a which is the bottom surface side of the concave portion 5, and the corner portion 5c where the above-described mounting surface 5a and the rising surface 5b are continuous as shown in FIG. With an acute angle, when an external force is applied to the disk substrate 2, internal stress is likely to be concentrated on the corner portion 5c, and there is a risk that it will be easily damaged.

Therefore, 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 is possible to make a face.

On the other hand, since the metal plate 6 is arranged in the recess 5 without causing a large displacement and is mounted in the recess 5 in a stable state, the metal plate 6 has an inner diameter of the recess 5. They are formed with substantially the same outer diameter. Therefore, the metal plate 6 is, as shown in FIG.
There is a risk that the mounting piece 6c may be fixedly disposed in the recess 5 while riding on the corner 5c having a gently curved surface. As a result, the metal plate 6 is not attached in parallel to the main surface 2a of the disk substrate 2, and the height from the mounting reference surface 7a of the bulging portion 7 to the disk table 12 to the main surface portion 6a of the metal plate 6 is increased. The accuracy of the height H ₁ (see FIG. 6) becomes unstable. That is, the centering member 13
The depth of the center hole 3 with which the centering member 13 engages becomes shallow, and it becomes impossible to guarantee a sufficient engagement amount of the centering member 13.

Therefore, according to the present invention, when the concave portion is formed in the disc substrate, the generation of a portion where the internal stress is concentrated is suppressed, the strength of the disc substrate is ensured, and the concave portion is accurately and stably formed. Another object of the present invention is to provide a disc for recording an information signal such as an optical disc that allows a magnetic attraction plate such as a metal plate to be arranged.

[0020]

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

[0021]

In the disc for recording information signals according to the present invention, the magnetic attraction plate disposed in the recess formed on one main surface side of the disc substrate so as to surround the center hole is provided in the recess. The curved portion provided in a portion where the placing surface and the rising surface are continuous has a depth that is lower than that of the above placing surface, thereby preventing the riding surface to a corner portion where the above placing surface and the rising surface are continuous. It is placed on the above placement surface.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention applied to an optical disk will be described below with reference to the drawings.

An optical disk 21 to which the present invention is applied, as shown in FIGS. 1 and 2, is a disk substrate 2 formed by molding a synthetic resin such as a polycarbonate resin into a disc shape.
Equipped with 2. One main surface 2 of this disk substrate 22
An information signal recording layer on which a desired information signal is recorded is adhered to the 2a side. The optical disc 21 configured by using the disc substrate 22 is the above-mentioned disc substrate 22.
The other main surface 22b opposite to the one main surface 22a on which the information signal recording layer is formed is used as an information signal writing / reading surface, and the signal recording layer is irradiated with a light beam from this writing / reading surface side. As a result, the information signal is recorded and reproduced.

Then, in the disc substrate 22 constituting the small-sized optical disc 21 having the diameter R of 64 mm,
It is formed with a thickness T _{3 of} 1.2 mm. Also,
This optical disc 21 has an inner diameter of 32 mm.
The outer peripheral side portion excluding the area is used as a signal recording area portion D where the information signal is recorded.

Further, in the central portion of the disc substrate 22, the disc rotation driving device 1 constructed as described above is provided.
A center hole 23 is formed in which the centering member 13 arranged on the side of the disk table 12 is engaged.
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, on the other main surface 22b side of the disk substrate 22, in the non-signal recording area E which is not the signal recording area D, an annular bulging portion 24 is formed so as to surround the center hole 23. Are integrally formed.
The bulging portion 24 increases the depth of the center hole 23 formed in the thin disc substrate 32, so that the centering member 13 disposed on the disc table 12 side is formed.
It is possible to increase the amount of protrusion of the above with respect to the center hole 23. That is, the bulging portion 24
Makes it possible to sufficiently increase the height of the centering member 13 that engages with the center hole 23, and the relative movement amount of the optical disc 21 and the centering member 13 during the mounting operation of the optical disc 21 on the disc table 12. The function of ensuring that the centering operation of mounting the optical disk 21 with the rotation center of the optical disk 21 aligned with the axis of the disk table 12 is performed reliably.

The bulging portion 24 is provided with a protrusion height H ₂ which is substantially the same as the thickness T _{3 of the} main portion of the disc substrate 22 in which the signal recording area is formed. Mounting reference surface 24 on the disk mounting surface 12a
a.

Furthermore, on the one main surface 22a side of the disk substrate 22, a circular ring-shaped recess is provided so as to surround the center hole 23 and accommodate a metal plate 25 which is a magnetic attraction plate. 26 is formed. The concave portion 26 has a diameter smaller than the outer peripheral diameter r of the bulging portion 24 and is formed to a depth D ₂ which is substantially equal to the thickness T ₃ of the main body portion of the disk substrate 22.

By thus forming the recess 26 for accommodating the metal plate having a depth approximately 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 portion 28 is formed on the inner peripheral side of the bottom surface portion of the recess 26 which becomes the mounting surface 27 of the metal plate 25. The step portion 28 prevents the protrusion surface such as a burr from being generated on the mounting surface 27 of the metal plate 25 when the concave portion 26 is formed, and maintains the above-described mounting surface 27 as a smooth surface. It is a thing.

On the other hand, the metal plate 25 housed in the recess 26 does not increase the weight of the optical disk 21 and has a thickness t of about 0.4 mm and is made of stainless steel having a thin magnetic property in consideration of workability. It is formed by punching a metal material such as a plate (SUS-430) into a disc shape.

As shown in FIG. 1, the metal plate 25 is formed in a disk shape having an outer peripheral diameter substantially the same as or slightly smaller than the inner peripheral diameter of the recess 26 which can be accommodated in the recess 26. is there. The metal plate 25 is centered at the center of the metal plate 25.
A positioning hole 29 is formed so as to be housed in the recess 26 so as to be aligned with the center of the position 2.
The positioning hole 29 also functions as a jig insertion hole for gripping the metal plate 25 when the metal plate 25 is housed in the recess 26.

By the way, if the metal plate 25 is simply formed in the shape of a flat disk, it is housed in the recess 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 in the center of the recess 26 is reduced.

Therefore, the metal plate 25 used in the present invention has a rising portion 30 formed by bending on the outer peripheral portion side. The rising portion 30 is formed at a height such 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 recess 26. A mounting piece 31 is formed on the mounting surface 27 in the recess 26 in parallel with the main surface portion 25a on the outer peripheral edge side of the rising portion 30. That is, as shown in FIG. 1, the metal plate 25 is formed in a disk shape having a concave shape as a whole.

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

Fixing in the recess 26 of the metal plate 25 is not limited to joining using an adhesive, and as shown in FIG. 3, a part of the peripheral edge of the recess 26 is thermally deformed to support the support projection 32. Alternatively, the metal plate 25 may be supported by the support protrusion 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 recess 26 in which the metal plate 25 of the disk substrate 22 constituting the present invention is housed and arranged, and the recess 26. As shown in FIG. 4, a groove-shaped curved portion 36 having a depth lower than that of the placing surface 27 is formed at a portion corresponding to a corner portion where the rising surface 35 which is the peripheral surface is continuous. The curved portion 36 is formed in the concave portion 2
It is formed over the entire circumference of the portion corresponding to the corner portion of 6.

As shown in FIG. 4, the curved portion 36 is formed as a groove portion having a substantially U-shaped cross section having arc portions 36a and 36b having constant curvatures on both sides. The curved portion 36 is formed with a depth D ₃ that is deeper than the height of the arc portion 36a formed on the surface of the rising surface 35. That is, the rising surface 3 above the mounting surface 27
Reference numeral 5 is a surface perpendicular to the mounting surface 27.

By forming such a curved surface 36 in a portion where the mounting surface 27 and the rising surface 35 are continuous in the concave portion 26, when the metal plate 25 is housed in the concave portion 26, the metal The mounting piece 31 of the plate 25 is supported on the mounting surface 27 without riding on the surface of the rising surface 35. Therefore, the metal plate 25 is attached to the disk substrate 22.
Of the bulging portion 24 and the height H ₃ from the mounting reference surface 24a to the disk table 12 to the main surface portion 25a of the bulge portion 24a is kept constant, and the recess 2 is formed.
6 can be stored 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 are continuous in the concave portion 26, 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-mentioned embodiment, the example applied to the optical disk has been described, but a disk provided with a synthetic resin disk substrate on which a recess for arranging a plate for magnetic attraction is formed. By applying
It is possible to achieve the same effects as those of the above embodiment.

[0042]

As described above, in the disc for recording information signals according to the present invention, the curved portion is formed in the portion where the mounting surface and the rising surface are continuous in the concave portion in which the plate for magnetic attraction is arranged. Since it is formed, it is possible to avoid concentration of internal stress in a portion where the mounting surface and the rising surface are continuous, and it is possible to sufficiently secure the strength of the disk substrate in which the recess is formed. .

Further, since the curved portion is formed so as to have a depth which is lower than the mounting surface in the recess, the magnetic attraction plate is securely supported by the mounting surface and the inside of the recess is formed. It is possible to prevent the plate from being inclinedly arranged in the recess,
It is possible to prevent an error from being given to the depth of the center hole formed in the disc substrate.

In particular, like the optical discs of the above-described embodiments, when forming the bulging portion on the disc substrate, the metal plate is arranged so that the bulging portion has the same thickness as the main portion of the disc substrate. By providing the curved portion as described above even when the thickness of the connecting portion of the bulging portion to the disk substrate cannot be sufficiently obtained by forming the depth of the concave portion Since the concentration of internal stress on the connecting portion can be avoided, sufficient strength guarantee of the disk substrate can be realized, so that it is possible to form a disk with extremely small molding accuracy.

[Brief description of 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 partial enlarged cross-sectional view showing a curved portion provided in a concave portion formed in a disc substrate that constitutes an optical disc according to the present invention.

FIG. 5 is a cross-sectional view of a conventional optical disc clamped on a disc table.

FIG. 6 is a partially enlarged sectional view of the conventional optical disc.

FIG. 7 is an enlarged cross-sectional view showing a recessed portion in which a metal plate formed on a disk substrate which constitutes the conventional optical disk is arranged.

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

[Explanation of symbols]

 21 optical disk 22 disk substrate 23 center hole 24 bulge 25 metal plate 26 recess 27 mounting surface 31 mounting plate of metal plate 35 rising surface of recess 36 curved portion

Claims (1)

[Claims] 1. A disk substrate made of a synthetic resin, which has a magnetic attraction plate, a center hole in the center, and a recess in which the plate is disposed on one main surface side surrounding the center hole. And a mounting surface of the plate is formed on the bottom surface side of the recess of the disc substrate, and the depth at which the mounting surface and the rising surface of the recess are continuous is deeper than the mounting surface. A disc for recording an information signal, the disc having a curved portion formed therein.