JP3208914B2 - Disk substrate and mold device for disk substrate molding - 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 substrate constituting a disk serving as an information signal recording medium such as an optical disk or a magneto-optical disk, and a disk substrate molding metal for molding the disk substrate with a synthetic resin material. Molding device.

[0002]

2. Description of the Related Art Hitherto, an optical disk using a disk substrate formed of a synthetic resin material such as a polycarbonate resin having a light transmitting property has been proposed. As this type of optical disk, a read-only optical disk that only reproduces an information signal recorded in advance and a rewritable magneto-optical disk that can rewrite an information signal once recorded are known. .

A read-only optical disk is formed by, for example, depositing aluminum or the like on one main surface side of a disk substrate on which a so-called pit, which is a concavo-convex pattern corresponding to an information signal such as a predetermined tone signal, is formed. It is provided with a reflective film.

In a magneto-optical disk capable of rewriting information signals, a signal having a magnetic film on one main surface of a disk substrate on which a pre-groove forming a recording track on which a desired information signal is recorded is formed. It is configured by forming a recording layer.

[0005] An optical disk of this kind can record information signals such as digitized musical sound signals at an extremely high density. Therefore, the present applicant has proposed an optical disk having a diameter of 64 mm and capable of recording and reproducing or at least reproducing only a tone signal of 74 minutes.

Here, a description will be given of a magneto-optical disk. As shown in FIG. 7, the magneto-optical disk 101 is a disk substrate formed by molding a synthetic resin material such as a polycarbonate resin having a light transmitting property. 102. As shown in FIG. 8, a signal recording layer 103 composed of a perpendicular magnetization film is formed on one main surface 102a of the disk substrate 102, and the Kerr rotation angle is increased on the signal recording layer 103. For this purpose, a dielectric film 104 having a thickness of λ / 4n is formed on the dielectric film 104, and a protective film 105 made of a synthetic resin material or the like is further formed on the dielectric film 104.

The recording of the information signal on the magneto-optical disk 101 is performed by recording the information signal on a signal recording section provided with a signal recording layer 103 while the magneto-optical disk 101 is rotated at a predetermined rotational speed. This is performed by irradiating a track with a light beam emitted from an optical pickup and applying an external magnetic field modulated in accordance with an information signal to be recorded from an external magnetic field generator.

The magneto-optical disk 101 has a small diameter and fine recording tracks formed at a high density.
As shown in FIG. 10, the magneto-optical disk 101 is accurately positioned and mounted on a disk table 110 of a disk rotation drive mechanism (not shown) provided in a disk recording and / or reproducing apparatus for rotating the magneto-optical disk 101. Therefore, it is necessary to rotate the disk table 110 in synchronization with the rotation of the disk table 110.

Therefore, a disk table 110 is mounted on a disk table 110 at the center of the other main surface 102b opposite to the one main surface 102a on which the signal recording layer 103 is formed, of the disk substrate 102 constituting the magneto-optical disk 101. A bulging portion 112 having a mounting reference surface 111 for accurately locating the height position is formed on a front end surface thereof.

The bulging portion 112 is provided at the center at the center of rotation of the disk table 110, and is mounted on the disk table 110.
A centering member engaging hole 114 with which a centering member 113 for centering is engaged is formed, and is formed in a ring shape as a whole. The centering member engaging hole 114 is formed so as to communicate with a center hole 115 formed in the disc substrate 102. The diameter of the centering member engaging hole 114 is the center hole 1
15 is smaller than the diameter of the engaging hole 114, and a flat ring-shaped hub mounting surface 116 is formed from the upper peripheral edge of the engaging hole 114 to the inner surface of the center hole 115.

Also, one main surface 1 of the disk substrate 102
A hub 117 made of a magnetic plate is disposed on the 02a side so as to close the center hole 115. The hub 117 has a shape in which a lower end surface of a peripheral portion thereof is placed and contacted on the hub mounting surface 116 and a central portion thereof is bulged upward.

This constitutes a so-called relief for increasing the height of the centering member 113. With this structure, the tapered surface 118 formed on the upper part of the centering member 113 can be widened. That is, the tapered surface 118 is for guiding the magneto-optical disk 101 inserted in the disk recording and / or reproducing apparatus to the disk table 110 side. Even if the optical disk 101 is inserted, the magneto-optical disk 101 can be reliably guided to the disk table 110 side.

The hub 117 mounted on the hub mounting surface 116 is attracted by a magnet 119 disposed on the disk table 110 side, whereby the magneto-optical disk 1 mounted on the disk table 110 is moved.
01 will be integrated with the disk table 110.

The magneto-optical disk 10 constructed as described above
1 is a centering member engaging hole 1 as shown in FIG.
14 is engaged with the centering member 113,
The mounting reference surface 111 formed on the distal end surface of the bulging portion 112 is supported by the disk support surface 110a of the disk table 110, and the hub 117 is attracted by the magnet 119 and mounted on the disk table 110. The rotation center of the disk table 110 is aligned with the center of the disk table 110, and the mounting height position is determined.

The disk substrate 102 constituting the magneto-optical disk 101 is formed by molding a synthetic resin material such as a polycarbonate resin using a mold apparatus for injection molding.

As shown in FIG. 11, a mold apparatus for molding the disk substrate 102 has a mold 13 comprising a fixed mold 131 and a movable mold 132 which are disposed to face each other.
3 is provided. When the fixed mold 131 and the movable mold 132 abut against each other, a shape corresponding to the disk substrate 102 to be formed is formed between the lower surface of the fixed mold 131 and the upper surface of the movable mold 132. Is formed.

Then, the center position of the fixed mold 131,
That is, the molding cavity 13 of the fixed die 131
An insertion hole 135 is formed at a center position of the lower surface of the lower surface 4 so as to be perpendicular to the lower surface. A substantially cylindrical sprue bush 136 is fitted and disposed in an insertion hole 135 formed in the fixed mold 131.

The sprue bush 136 has a resin injection passage 137 formed along the center axis. The sprue bush 136 is disposed with its tip end portion slightly protruding from the lower surface of the fixed mold 131, and has a concave portion having a depth corresponding to the thickness of the disk substrate 102 to be formed at the center thereof. An opening communicating with the resin injection passage 137 is formed at the center of the bottom of the recess 138 so that the resin injection passage 137 faces the molding cavity 134 through the opening. Therefore, the injection device (not shown) is connected to the resin injection passage 13.
The synthetic resin material such as polycarbonate resin supplied to the molding cavity 7 is supplied to the molding cavity 13 through the opening.
4 will flow.

The sprue bush 136 extends from the edge of the recess 138 toward the outer periphery thereof.
02, that is, the hub mounting surface 11
6 and an annular forming portion 139 for forming a surface including the center hole 115 are integrally formed. This forming part 13
Reference numeral 9 denotes an annular convex portion 140 having the inner surface of the concave portion 138 as an inner surface, and an annular concave portion 141 formed in the outer peripheral direction from the bottom of the outer surface of the annular convex portion 140.

A stamper 142 for forming a concave / convex pattern corresponding to an information signal or a pre-groove forming the recording track is mounted on the front surface of the molding cavity 134 of the fixed die 131. Is done.

The stamper 142 has a central hole 142
a is externally fitted on the outer peripheral surface on the distal end side of the sprue bush 136 and positioned. That is, the inner diameter of the center hole 142a is substantially the same as the outermost diameter of the sprue bush 136. The outer peripheral edge of the stamper 142 is held between the fixed die 131 and supported by an outer peripheral stamper holder (not shown) attached to the fixed die 131. The outer peripheral side stamper holder is formed in a substantially annular shape, is attached to the outer peripheral side on the lower surface side of the fixed die 131, and is provided with the molding cavity 13.
4 is the outer peripheral edge.

On the other hand, the movable mold 132 has a central portion at which the mounting reference surface 1 of the bulging portion 112 of the disk substrate 102 is mounted.
A concave portion 151 for forming the lower surface side including 11 is formed, and an insertion hole 152 extending in the axial direction is formed at the center of the bottom of the concave portion 151. That is, this insertion hole 15
Reference numeral 2 is provided at a front end surface of the sprue bush 136 supported by the fixed die 131, particularly at a position facing the concave portion 138 thereof. In a through hole 152 formed in the movable mold 132, a punching punch 1 having a cylindrical shape is provided.
53 is inserted and disposed, and furthermore, is inserted into the hollow portion 154 of the punch 153 to form a cylindrical push rod 1.
55 are provided.

The push rod 155 can move forward and backward with respect to the punch 153, and is supported by the punch 153. The punch 153 can move forward and backward with respect to the movable mold 132, and is supported by the movable mold 132. The punch 153 has the front end face facing the molding cavity 134 slightly immersed in the movable mold 132 rather than the upper surface of the movable mold 132. The pushing rod 155 has its front end face facing the molding cavity 134 slightly immersed in the punch 153.

To form the disk substrate 102 in the disk substrate molding die apparatus configured as described above, first, the movable die 132 is abutted against the fixed die 131 to form the molding cavity 134. . Then, the above-described injection device inserts the resin into the molding cavity 134 through the resin injection passage 137 of the sprue bush 136.
A synthetic resin material (not shown) such as molten polycarbonate is injected and filled.

At this time, the synthetic resin material flows in the molding cavity 134 from the center toward the outer periphery. Then, the movable mold 132 is moved to the fixed mold 131 side to compress the synthetic resin material filled in the molding cavity 134, that is, perform so-called mold clamping, and then cool. Then, the synthetic resin material filled in the molding cavity 134 is solidified, and the disk substrate 102 having a shape corresponding to the molding cavity 134 is formed as shown in FIG.
Is formed.

Then, the engaging hole 114 is formed by projecting the punch 153 toward the fixed mold 131. Thereafter, the disk substrate 102 thus formed is released from the fixed mold 131 by performing a so-called mold opening that separates the movable mold 132 from the fixed mold 131. Then, the extruding rod 155 is slid in the direction of the fixed mold 131 to extrude and remove the residue on the punch 153, and further, the disk substrate 102 is separated from the movable mold 132, as shown in FIG. like,
The molding of the disk substrate 102 is completed.

In the disk substrate 102, a pregroove forming a recording track on which an information signal is recorded is formed on one main surface portion 102a by a stamper 142. Then, a signal recording layer 103 made of a magnetic material is formed so as to cover the pregroove, and a dielectric film 104 and a protective film 105 are laminated on the signal recording layer 103.

Thereafter, the completed disk substrate 102
The magneto-optical disk 101 is completed by fixing a hub 117 made of a magnetic plate to a hub mounting surface 116 at the center of the upper surface of the magnetic disk using, for example, an adhesive.

[0029]

In the conventional disk substrate 102, a flat ring-shaped hub mounting surface 116 is formed from the upper peripheral edge of the engaging hole 114 to the inner surface of the center hole 115. It is,
The depth of the engagement hole 114, that is, the thickness of the bulging portion 112 is small.

Therefore, the inner peripheral end of the bulging portion 112 on the side of the engaging hole 114 is easily bent, and the lower surface of the bulging portion 112, that is, the mounting reference surface 111, vibrates due to the vibration accompanying the rotation of the disk table 110 or the like. There is a problem that the degree of adhesion between the mounting reference surface 111 and the disk support surface 110a is reduced. This causes the disk substrate 102 to spin or run out of surface, so that the recording and / or reproduction of the information signal on the magneto-optical disk 101 cannot be performed accurately.

Further, in the disk substrate molding die apparatus, the engaging holes 114 of the disk substrate 102 are formed by punching with a punch 153. At this time, the surface formed by the punching is
The surface accuracy becomes very high.

However, in the above-described punching process, the recess 138 provided at the center of the front end face of the sprue bush 136 functions as a relief for the punch 153. The recess 138 and the punch 153 are accurately positioned. It is difficult for the punch 153 to enter the punch 153 as the punch 153 enters.
The outer peripheral edge of 53 and the front end face of the annular convex portion 140 are partially opposed to each other.

Accordingly, the resin at the portion where the outer peripheral edge of the punch 153 and the front end surface of the annular convex portion 140 face each other is as follows:
When the punch 153 enters, the resin is crushed, and the resin in the crushed portion is forcibly pushed off by the punch 153. As a result, as shown in FIG. 9, a shearing surface 160 is formed on the inner surface of the engaging hole 114 of the completed disk substrate 102 by the above-described strong push-off. This shear plane 160
Has a very rough surface accuracy and its surface is uneven.

From this, the completed disk substrate 1
When 02 is used as the magneto-optical disk 101, the following problems occur.

That is, when the magneto-optical disk 101 is mounted on the disk table 110, the centering member 113 of the disk table 110 is engaged in the engaging hole 114 of the disk substrate 102. Since the thickness of the bulging portion 112 is small, the shearing surface 160 formed in the engagement hole 114 comes into contact with the side surface of the centering member 113 as shown in FIG. As described above, since the surface accuracy of the shear surface 160 is very rough,
Causes a misalignment when the optical disk 101 is mounted on the disk table 110, and a problem arises in that accurate alignment of the magneto-optical disk 101 cannot be achieved.

As described above, the conventional disk substrate 102
The surface accuracy of the engaging hole 114, which is a reference for centering the magneto-optical disk 101 with respect to the disk table 110, is poor.
Moreover, since the strength of the bulging portion 112 is low, there is a disadvantage that the mounting to the disk table 110 cannot be performed reliably.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an inner surface of an engagement hole which has a good surface accuracy in contact with a centering member, and has a bulging portion. An object of the present invention is to provide a disk substrate which has high strength and can be reliably mounted on a disk table.

According to another aspect of the present invention, the inner surface of the engagement hole has a good surface accuracy in contact with the centering member, the strength of the bulging portion is high, and the mounting to the disk table can be performed reliably. An object of the present invention is to provide a disk substrate molding die device capable of producing a disk substrate that can be formed by resin molding.

[0039]

According to the present invention, there is provided a disk substrate 2 formed in a disk shape from a resin material having optical transparency, and a centering member 14 of a disk rotation driving means 11 is engaged with a center of the disk substrate 2. A mounting portion 13 having an engagement hole 15 to be inserted, a hub storage recess 71 in which a hub 17 made of a magnetic material is stored and arranged around the engagement hole 15, and a mounting reference surface 12 for the disk rotation driving means 11. To form
An annular protruding portion 21 is formed integrally from the outer periphery of the engagement hole 15 on the side of the hub housing recess 71 toward the side where the hub 17 is housed and arranged.

In this case, the inner peripheral surface of the projecting portion 21 is provided with a punch 63 for punching the engaging hole 15.
Alternatively, the shearing portion 25 on the tip side in the punching direction may be configured.

According to another invention, a disk rotation driving means 1 is formed in the shape of a disk with a resin material having optical transparency.
An engagement hole 15 into which one centering member 14 is engaged;
A mounting portion 13 having a hub housing recess 71 in which a hub 17 made of a magnetic material is housed and arranged around the engagement hole 15, and a mounting reference surface 12 for the disk rotation driving means 11.
In the disk substrate molding die apparatus for producing the disk substrate 2 on which the fixed die 31 is formed, the fixed die 31 is opposed to the fixed die 31, and the fixed die 31 can be moved toward and away from the fixed die 31. A movable mold 32 disposed to form a molding cavity 34 with the fixed mold 31;
32, and a stamper 51 disposed in the molding cavity 34 and a resin 46 attached to one of the dies 31 and 32 and melted in the molding cavity 34. A sprue bush 42 having a resin injection passage 43 for guiding, a hub housing recess forming portion 49 for forming a hub housing recess 71 in the mounting portion 13, and one of the molds 31 and 32, And a punch 6 for punching and forming the engaging hole 15 of the disk substrate 2, which is disposed so as to be able to approach and separate from one of the molds 31 and 32.
3 and at the inner peripheral end of the hub housing concave portion forming portion 49,
From the outer periphery of the engagement hole 15 on the side of the hub storage recess 71, the hub 1
An annular notch 44 for forming a projecting portion for forming the annular projecting portion 21 projecting toward the side where the 7 is housed and arranged is formed.

In this case, the inner peripheral surface of the projecting portion 21 corresponds to the shearing portion 25 of the punching punch 63 on the tip side in the punching direction.
You may make it become. Further, the inner side surface of the annular cutout 44 for forming the protrusion may be formed as a tapered surface 47.

[0043]

In the disk substrate 2 according to the present invention, the annular protrusion 21 protrudes from the outer periphery of the engagement hole 15 on the side of the hub receiving recess 71 toward the side where the hub 17 is stored.
Are formed integrally, so that this annular projection 2
1, the substantial depth of the engaging hole 15 is increased, and as a result, the strength of the inner peripheral edge of the engaging hole 15 in the mounting portion 13 is increased, and the mechanical strength of the entire mounting portion 13 is increased. .

Therefore, the inner peripheral end of the mounting portion 13 on the engagement hole 15 side is unlikely to be bent, and the mounting reference surface 1
2 does not vibrate due to vibration or the like accompanying rotation of the disk rotation driving means 11, and mounting accuracy between the mounting reference surface 12 and the disk rotation driving means 11 increases. As a result, the disk substrate 2 is less likely to spin or run out, and when the disk substrate 2 is, for example, a magneto-optical disk 1, information signals can be recorded and / or reproduced accurately.

The engagement hole 15 is provided with a punch 63
Formed by punching,
Since the inner surface of the annular projecting portion 21 becomes the shearing surface 25 on the tip side in the punching direction of the punch 63 for punching the engagement hole 15, the entire inner surface of the engagement hole 15 is
The surface accuracy is high. Therefore, the centering member 1
4 does not come into contact with the shear surface 25 having a high surface accuracy, and engages with the engaging hole 15 having a high surface accuracy. As a result, misalignment does not occur when the disk substrate 2 is mounted on the disk rotation driving means 11, and, for example, the magneto-optical disk 1 can be accurately aligned.

In a disk substrate molding die apparatus according to another invention, first, a movable cavity 32 is abutted against a fixed mold 31 to form a molding cavity 34.
Then, the molten resin 46 is injected and filled into the molding cavity 34 through the resin injection passage 43 of the sprue bush 42 by the injection device.

At this time, the resin 46 flows in the molding cavity 34 from the center to the outer periphery. Then, the movable mold 32 is moved to the fixed mold 31 side to compress the resin filled in the molding cavity 34, that is, perform so-called mold clamping, and then cool. At this time, the resin filled in the molding cavity 34 is solidified, and the disk substrate 2 having a shape corresponding to the molding cavity 34 is formed.

Then, by making the punch 63 project, the engagement hole 15 is formed. Thereafter, the disk substrate 2 thus formed is released from the fixed mold 31 by performing a so-called mold opening that separates the movable mold 32 from the fixed mold 31. Then, the disk substrate 2
Is separated from the movable mold 32 to complete the formation of the disk substrate 2.

In the injection molding by the disk substrate molding die apparatus according to another aspect of the present invention, the stamper 51 forms, for example, a pre-recording track on which the information signal is recorded on one main surface 2a of the disk substrate 2 by the stamper 51. Grooves and the like are formed, and a hub storage recess 71 in the mounting portion 13 is formed by the hub storage recess forming portion 49, and an annular notch 44 for forming a protrusion formed at an inner peripheral end of the hub storage recess forming portion 49. As a result, the hub storage recess 71 of the engagement hole 15
An annular protrusion 21 is formed from the outer periphery of the side toward the side where the hub 17 is housed and arranged.

In the formed disk substrate 2, the substantial depth of the engagement hole 15 is increased by the annular projection 21 formed by the annular notch 44 for forming the projection.
As a result, the strength of the inner peripheral edge of the engagement hole 15 in the mounting portion 13 increases, and the mechanical strength of the entire mounting portion 13 increases.

Therefore, the inner peripheral end of the mounting portion 13 on the engagement hole 15 side is unlikely to be bent, and the mounting reference surface 1
2 does not vibrate due to vibration or the like accompanying rotation of the disk rotation driving means 11, and mounting accuracy between the mounting reference surface 12 and the disk rotation driving means 11 increases. As a result, the disk substrate 2 is less likely to spin or run out, and when the disk substrate 2 is, for example, a magneto-optical disk 1, information signals can be recorded and / or reproduced accurately.

The engaging hole 15 in the mounting portion 13 of the disk substrate 2 is formed by punching with a punch 63. At this time, since the inner surface of the annular projecting portion 21 becomes the shearing surface 25 on the distal end side in the punching direction of the punch 63 for punching the engaging hole 15, the entire inner surface of the engaging hole 15 has high surface accuracy. It will be. Therefore, the centering member 14 does not come into contact with the shear surface 25 having a high surface accuracy, and engages with the engaging hole 15 having a high surface accuracy. As a result, misalignment does not occur when the disk substrate 2 is mounted on the disk rotation driving means 11, and accurate centering of the magneto-optical disk 1 can be performed.

Therefore, in the disk substrate molding die according to another invention, the surface accuracy of the inner surface of the engagement hole 15 in contact with the centering member 14 is good.
The disk substrate 2 which has a high strength of the mounting portion 13 and can be reliably mounted on the disk rotation driving means 11 can be manufactured by resin molding.

[0054]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific embodiment in which a disk substrate according to the present invention is applied to a disk substrate of a magneto-optical disk having a diameter of 64 mm (hereinafter simply referred to as a disk substrate according to the embodiment) will be described with reference to FIGS. This will be described with reference to FIG.

As shown in FIG. 1, the magneto-optical disk 1 has a disk substrate 2 according to the present embodiment formed by molding a synthetic resin material such as a transparent polycarbonate resin.
It has. The disk substrate 2 has a diameter of approximately 64
mm and a thickness of approximately 1.2 mm.

As shown in FIG. 2, a signal recording layer 3 made of a perpendicular magnetization film is formed on one main surface 2a of the disk substrate 2, and a Kerr rotation angle is formed on the signal recording layer 3. In order to increase the thickness, a dielectric film 4 having a film thickness of λ / 4n is formed thereon, and a protective film 5 made of a synthetic resin material or the like is further formed on the dielectric film 4.

The recording of information signals on the magneto-optical disc 1 is performed by recording tracks provided on a signal recording section provided with a signal recording layer 3 while rotating the magneto-optical disc 1 at a predetermined rotational speed. By irradiating a light beam emitted from an optical pickup with the external magnetic field, and applying an external magnetic field modulated in accordance with an information signal to be recorded from an external magnetic field generator.

Since the magneto-optical disk 1 has a small diameter and fine recording tracks formed at a high density, the disk recording and / or rotating operation of the magneto-optical disk 1 is performed as shown in FIG. Alternatively, it is necessary that the disk rotation drive mechanism (not shown) provided in the playback apparatus be accurately positioned and mounted on the disk table 11, and be rotated and driven in synchronization with the rotation of the disk table 11. is there.

Therefore, one main surface 2a of the disk substrate 2 of the magneto-optical disk 1 on which the signal recording layer 3 is formed.
A bulging portion 13 is formed at the center of the other main surface 2b opposite to the bulging portion 13 having a mounting reference surface 12 for accurately locating a mounting height position on the disk table 11 formed at a front end surface. .

The bulging portion 13 is provided at the center thereof at the center of rotation of the disk table 11, and engages with a centering member 14 for centering the magneto-optical disk 1 mounted on the disk table 11. A centering member engaging hole 15 is formed, and is formed in a ring shape as a whole.

The centering member engaging hole 15 is formed so as to communicate with a center hole 16 formed in the disc substrate 2. This centering member engaging hole 15
Has a diameter smaller than the diameter of the center hole 16. Therefore, in the upper center of the disk substrate 2,
A concave portion 71 having a flat circular shape and having the engagement hole 15 at the bottom is formed. The hub 17 made of a magnetic plate is disposed in the recess 71 so as to close the center hole 16. For this reason, the concave portion 71
Constitutes a recess for accommodating the hub 17.

In this embodiment, an annular projection 21 projecting upward from the outer periphery of the upper surface of the engagement hole 15 is formed integrally. The projecting amount of the annular projecting portion 21 is set to be smaller than the height H of the inner step of the hub 17. Then, the protrusion 21
The peripheral surface facing the center hole 16 is a tapered surface 21a. In addition, the center hole 16 can be
A flat ring-shaped surface 22 is formed over the inner surface of
This surface 22 constitutes a hub mounting surface for mounting the hub 17.

The hub 17 has a shape in which a lower end surface of a peripheral portion thereof is placed and contacted on the hub mounting surface 22 and a central portion thereof bulges upward. This constitutes a so-called relief for increasing the height of the centering member 14, and by this structure, the tapered surface 23 formed on the upper part of the centering member 14 can be widened. That is, the tapered surface 23 is for guiding the magneto-optical disk 1 inserted into the disk recording and / or reproducing apparatus to the disk table 11 side. Even if inserted, the magneto-optical disk 1 can be reliably guided to the disk table 11 side.

The hub 17 mounted on the hub mounting surface 22 is attracted by a magnet 24 disposed on the disk table 11 side, whereby the magneto-optical disk 1 mounted on the disk table 11 is moved to the disk table 11. 11 will be integrated.

The magneto-optical disk 1 thus configured
As shown in FIG. 4, the centering member engaging hole 15 is engaged with the centering member 14 and
3 is supported on the disk support surface 11a of the disk table 11, and the hub 17 is attracted to the magnet 24 and mounted on the disk table 11, whereby the disk table 11 is mounted. 1
The center of rotation is aligned with the center of rotation of the disk drive 1 and the mounting height position is determined.

As described above, in the disk substrate 2 according to the above embodiment, the annular projecting portion 21 projecting from the outer periphery of the engaging hole 15 on the hub mounting surface 22 side toward the mounting side of the hub 17 is integrally formed. Due to the formation, the annular projection 21 increases the substantial depth of the engagement hole 15, and as a result, the strength of the inner peripheral edge of the engagement hole 15 in the bulging portion 13 is increased. As a result, the mechanical strength of the entire bulging portion 13 increases.

Therefore, the inner peripheral end of the bulging portion 13 on the engagement hole 15 side is unlikely to be bent, and the mounting reference surface 1
2 does not vibrate due to vibrations or the like accompanying rotation of the disk table 11, and the degree of adhesion between the mounting reference surface 12 and the disk table 11 increases. by this,
The disk substrate 2 is less likely to spin or run out, and the recording and / or reproduction of information signals when the disk substrate 2 is the magneto-optical disk 1 can be performed accurately.

The engaging hole 15 is formed by punching using a punch.
As shown in FIG. 5, the inner surface of the annular projection 21 is a shearing surface 25 on the tip side in the punching direction of a punch for punching the engagement hole 15, so that the entire inner surface of the engagement hole 15 has surface accuracy. It will be expensive. Therefore, when the magneto-optical disk 1 is mounted on the disk table 11,
As shown in FIG. 4, the centering member 14 engaged with the engagement hole 15 of the disc substrate 2
5 does not contact, and engages with the engaging hole 15 having high surface accuracy. As a result, misalignment does not occur when the disk substrate 2 is mounted on the disk table 11, and accurate centering of the magneto-optical disk 1 can be performed.

The disk substrate 2 constituting the magneto-optical disk 1 is formed by molding a synthetic resin material such as a polycarbonate resin using a mold device for injection molding. Hereinafter, a mold apparatus for molding the disk substrate 2 will be described with reference to FIGS.

As shown in FIG. 5, the mold apparatus for molding the disk substrate 2 is provided with a molding mold 33 comprising a fixed mold 31 and a movable mold 32 which are arranged to face each other. Have been. A molding cavity 34 (see FIG. 6) corresponding to the disk substrate 2 to be molded is defined between the fixed mold 31 and the movable mold 32 constituting the molding die 33.

The fixed mold 31 is attached to the fixed mounting base 3.
6 is supported via mounting means (not shown). The movable mold 32, which is operated to move toward and away from the fixed mold 31, is supported by a movable mounting base 37 driven by driving means such as a hydraulic drive mechanism via mounting means (not shown). I have.

At the center position of the fixed mold 31, that is, at the center position of the lower surface of the molding cavity 34 of the fixed mold 31, an insertion hole 41 is provided in a direction perpendicular to the lower surface. Is formed. A substantially cylindrical sprue bush 42 is fitted and disposed in an insertion hole 41 formed in the fixed mold 31.

As shown in FIG. 6, the sprue bush 42 has a resin injection passage 43 formed along the central axis. The sprue bush 42 is disposed with its tip end portion slightly projecting from the lower surface of the fixed mold 31, and has a diameter equal to the diameter of the engagement hole 15 of the disk substrate 2 at the center thereof. And a recess 45 having a depth corresponding to the thickness of the disk substrate 2 is formed.

The sprue bush 42 includes the upper surface portion of the bulging portion 13 of the disk substrate 2, that is, the hub mounting surface 22 and the center hole 16, which constitute the hub housing concave portion 71, in the outer peripheral direction of the concave portion 45. An annular forming portion 48 for forming a surface is integrally formed. This forming part 48
Are annular convex portions 49 having the inner surface of the concave portion 45 as an inner surface.
And an annular concave portion 50 formed in the outer peripheral direction from the bottom of the outer surface of the annular convex portion 49.

In this embodiment, an annular notch 44 is formed at the inner peripheral end of the annular convex portion 49 in the annular forming portion 48, and the annular notch 44 has a depth. , About 1 of the depth corresponding to the thickness of the disk substrate 2
/ 3, and the inner surface thereof is a tapered surface 47.

An opening communicating with the resin injection passage 43 is formed at the center of the bottom of the concave portion 45.
3 faces the molding cavity 34 through the opening. Therefore, the molten synthetic resin material 46 (see FIG. 1) such as polycarbonate resin supplied from the injection device (not shown) to the resin injection passage 43 flows into the molding cavity 34 through the opening. The inner surface of the annular notch 44 has a tapered surface 47.
It has been.

Further, on the front surface of the molding cavity 34 of the fixed mold 31, a stamper 51 for forming a concavo-convex pattern corresponding to an information signal or a pre-groove constituting the recording track is mounted. Is done.

The stamper 51 is positioned by fitting its center hole 51 a to the outer peripheral surface on the distal end side of the sprue bush 42. That is, the inner diameter of the center hole 51a is substantially the same as the outermost diameter of the sprue bush 42. In the peripheral portion on the tip end side of the sprue bush 42, a central hole 51 a of the stamper 51 protrudes toward the molding cavity 34.
A fitting protrusion 52 is provided to be fitted.

The fitting projection 52 is formed in a cylindrical shape having an outer diameter substantially the same as that of the center hole 51a so that the center hole 51a of the stamper 51 can be fitted substantially closely. That is,
The outer peripheral surface of the fitting projection 52 serves as a mounting position regulating surface for positioning the mounting position of the stamper 51 mounted on the fixed mold 31 side. Accordingly, the stamper 51 can be mounted centered on the fixed mold 31 by fitting the center hole 51 a into the fitting projection 52.

The stamper 51 is, as shown in FIG.
The outer peripheral side is sandwiched and supported by the outer peripheral side stamper holder 53 attached to the stationary die 31. This outer stamper holder 5
3 is formed in a substantially annular shape, is attached to the outer peripheral portion on the lower surface side of the fixed mold 31, and forms the molding cavity 3.
4 constitute the outer peripheral portion.

On the other hand, the movable mold 32 has
A concave portion 61 for forming the lower surface side including the mounting reference surface 12 of the bulging portion 13 of the disk substrate 2 is formed.
An insertion hole 62 extending in the axial direction is formed at the center position of the bottom of the device 1. That is, this insertion hole 62 is
The sprue bush 42 is supported at the front end face of the sprue bush 42, particularly at a position facing the recess 45. In a through hole 62 formed in the movable mold 32, a punching punch 63 having a cylindrical shape is inserted and disposed.
A cylindrical push rod 65 is provided so as to fit into the hollow portion 64 of the punch 63.

The push rod 65 can move forward and backward with respect to the punch 63 and is supported by the punch 63. Also, this punch 63
Is movable with respect to the movable mold 32 and is supported by the movable mold 32. The punch 63 has its front end face facing the molding cavity 34 slightly immersed in the movable mold 32 rather than the upper surface of the movable mold 32. Then, the pushing rod 65 is used to press the front end face facing the molding cavity 34 into the punch 6.
It is slightly immersed in 3.

To form the disk substrate 2 in the disk substrate molding die apparatus configured as described above, first, the movable die 32 is abutted against the fixed die 31 to form the molding cavity 34. . Then, the synthetic resin material 46 (see FIG. 1) such as molten polycarbonate is injected and filled into the molding cavity 34 through the resin injection passage 43 of the sprue bush 42 by the injection device.

At this time, the synthetic resin material 46 flows in the molding cavity 34 from the center to the outer periphery. Then, the movable mold 32 is moved to the fixed mold 31 side to compress the synthetic resin material filled in the molding cavity 34, that is, perform so-called mold clamping, and then cool.
At this time, the synthetic resin material 46 filled in the molding cavity 34 is solidified, and the disk substrate 2 having a shape corresponding to the molding cavity 34 is formed as shown in FIG.

Then, the punch 63 is fixed to the fixed mold 3.
The engagement hole 15 is formed by protruding toward one side.
Thereafter, the movable mold 32 is separated from the fixed mold 31.
By performing the so-called mold opening, the molded disk substrate 2 is released from the fixed mold 31. Then, the extruding rod 65 is slid in the direction of the fixed mold 31 to extrude and remove the residue on the punch 63, and further, the disk substrate 2 is separated from the movable mold 32, as shown in FIG. Thus, the molding of the disk substrate 2 is completed.

In the injection molding by the disk substrate molding die apparatus according to this embodiment, the stamper 51 forms a pre-recording track on which the information signal is recorded on one main surface 2a of the disk substrate 2 by the stamper 51, for example. A groove is formed, and an annular forming portion 48 (particularly, an annular convex portion 49) is formed.
As a result, the hub mounting surface 22 of the bulging portion 13 is formed, and the annular notch 44 protrudes from the outer periphery of the engagement hole 15 on the hub mounting surface 22 side toward the hub mounting side. 21 (see FIG. 2) is formed.

As shown in FIG. 2, a signal recording layer 3 made of a magnetic material is formed so as to cover the pregroove, and a dielectric film 4 and a protective film 5 are sequentially laminated on the signal recording layer 3. Is done. Then, the completed disk substrate 2
By fixing the hub 17 made of a magnetic plate to the hub mounting surface 22 at the center of the upper surface of the
The magneto-optical disk 1 shown in FIG. 1 is completed.

When a hub is mounted on the hub mounting surface 22, the following method may be employed. That is, the tip of the vibration applicator is brought into contact with the periphery of the center hole 16, and ultrasonic vibration in the circumferential direction is applied to the periphery of the center hole 16 in parallel with one main surface 2 a of the disk substrate 2, The hub 17 is held in the center hole 16 by thermally deforming at least a part of the periphery of the hub 16.
In this case, attachment of the hub 17 to the hub attachment surface 22 becomes very easy.

As described above, the disk substrate 2 formed by the disk substrate forming die apparatus is substantially deepened in the engagement hole 15 by the annular projection 21 formed by the annular notch 44. As a result, the strength of the inner peripheral edge of the engagement hole 15 in the bulging portion 13 increases,
The mechanical strength of the entire bulging portion 13 is increased.

Therefore, the inner peripheral end of the bulging portion 13 on the engagement hole 15 side is unlikely to be bent, and the mounting reference surface 1
2 does not vibrate due to vibrations or the like accompanying rotation of the disk table 11, and the mounting accuracy between the mounting reference surface 12 and the disk table 11 is improved. As a result, the disk substrate 2 is less likely to spin or run out, and the recording and / or reproduction of information signals when the disk substrate 2 is the magneto-optical disk 1 can be performed accurately.

In the punching of the engaging hole 15 by the punch 63, the recess 45 provided at the center of the front end surface of the sprue bush 42 functions as a relief for the punch 63. It is difficult to accurately position the punch 63 and the punch 63, and due to the misalignment, the outer peripheral edge of the punch 63 and the bottom of the annular notch 44 partially face each other as the punch 63 enters. It is a form to be done.

Therefore, the resin at the portion where the outer peripheral edge of the punch 63 is opposed to the bottom of the annular notch 44 is crushed by the penetration of the punch 63, and the resin at the crushed portion is removed by the punch 63. By approach
You will be forcibly pushed off. As a result, as shown in FIG. 2, the annular projection 21 protrudes from the outer periphery of the engagement hole 15 of the completed disk substrate 2 on the hub mounting surface 22 side toward the mounting side of the hub 17. On its inner surface, a shear surface 25 is formed by the above-described strong push-cutting. The shear surface 25 has a very rough surface accuracy and its surface is uneven.

Thus, the formed annular projection 21 is formed.
Inner surface is a shearing surface 25 on the tip side in the punching direction of the punching punch 63 for punching the engaging hole 15, so that the entire inner surface of the engaging hole 15 is a purely formed surface formed by the punching punch 63, and the surface accuracy is improved. It will be expensive. Therefore, the centering member 14 is provided with a shear surface 2 having a rough surface accuracy.
5 does not contact, and engages with the engaging hole 15 having high surface accuracy. As a result, misalignment does not occur when the disk substrate 2 is mounted on the disk table 11, and accurate centering of the magneto-optical disk 1 can be performed.

Thus, in this disk substrate molding die apparatus, the surface accuracy of the inner surface of the engaging hole 15 in contact with the centering member 14 is good, and the strength of the bulging portion 12 is high. The disk substrate 2 that can be securely mounted on the disk table 11 can be manufactured by resin molding.

In particular, in this embodiment, since the inner surface of the annular notch 44 is formed as a tapered surface 47, the synthetic resin material 46 such as a molten polycarbonate resin flowing through the opening of the resin injection passage 43 is formed. Can flow uniformly and efficiently into the entire cavity 34,
The time required for injection molding can be reduced and the quality of the disk substrate 2 can be improved.

In the above embodiment, an example in which the present invention is applied to the magneto-optical disk 1 has been described. However, the present invention can also be applied to a read-only optical disk or the like.
The present invention can be applied to all disks having an engagement hole 15 that engages with the disk.

[0097]

As described above, according to the disk substrate of the present invention, the disk substrate is formed in a disk shape from a resin material having optical transparency, and the center of the disk rotation driving means is provided at the center thereof. An engagement hole into which the member is engaged,
A mounting portion having a hub housing recess in which a hub made of a magnetic material is housed and arranged around the engagement hole, and a mounting reference surface for the disk rotation driving means are formed. An annular projection that projects from the outer periphery of the hub toward the side where the hub is housed and arranged is integrally formed, so that the inner surface of the engagement hole has good surface accuracy on the surface that contacts the centering member. In addition, the strength of the bulging portion is high, and the mounting to the disk rotation driving means can be reliably performed.

According to the disk substrate molding die apparatus of another invention, a disk-shaped resin-transparent resin material is formed, and the centering member of the disk rotation driving means is engaged with the center. An engagement hole, a hub housing recess in which a hub made of a magnetic material is housed and arranged around the engagement hole,
In a disk substrate molding die apparatus for producing a disk substrate on which a mounting portion having a mounting reference surface for the disk rotation driving means is formed, a fixed die, and a fixed die facing the fixed die. A movable mold that is disposed so as to be able to approach and separate from the mold and forms a molding cavity between the fixed mold and the movable mold, and is attached to at least one of the molds. A stamper to be disposed, a sprue bush having a resin injection passage attached to one of the molds and guiding a molten resin into the molding cavity, and a hub receiving recess in the mounting portion. The hub receiving recess forming portion and one of the respective molds are opposed to each other, and are disposed so as to be able to be moved toward and away from one of the respective molds. And a punch of the order,
Forming a protruding portion at the inner peripheral end of the hub receiving recess forming portion to form an annular protruding portion protruding from the outer periphery of the engagement hole on the side of the hub receiving recess toward the side where the hub is stored and arranged. Annular notch, the surface accuracy of the surface in contact with the centering member in the inner surface of the engaging hole is good, and the strength of the bulging portion is high, so that the mounting to the disk rotation drive means is ensured. A disk substrate that can be manufactured at a time can be manufactured by resin molding.

[Brief description of the drawings]

FIG. 1 shows a disk substrate according to the present invention having a diameter of 64 mm.
FIG. 1 is a perspective view showing a specific example (hereinafter, simply referred to as a disk substrate according to an example) applied to a disk substrate of a magneto-optical disk, which is partially cut away.

FIG. 2 is a cross-sectional view partially showing a magneto-optical disk constituted by a disk substrate according to the present embodiment;

FIG. 3 is an enlarged sectional view showing a bulging portion of the magneto-optical disk constituted by the disk substrate according to the embodiment.

FIG. 4 is a sectional view of a main part showing a state in which a magneto-optical disk constituted by a disk substrate according to the present embodiment is mounted on a disk table.

FIG. 5 is a sectional view showing a disk substrate molding die apparatus for producing a disk substrate by injection molding according to the present embodiment.

FIG. 6 is an enlarged sectional view of a main part of a disk substrate molding die apparatus for producing a disk substrate by injection molding according to the present embodiment.

FIG. 7 is a perspective view showing a magneto-optical disk constituted by a disk substrate according to a conventional example, partially cut away.

FIG. 8 is a cross-sectional view partially showing a magneto-optical disk constituted by a disk substrate according to a conventional example.

FIG. 9 is an enlarged sectional view showing a bulging portion of a magneto-optical disk constituted by a disk substrate according to a conventional example.

FIG. 10 is a cross-sectional view of a main part showing a state where a magneto-optical disk including a disk substrate according to a conventional example is mounted on a disk table.

FIG. 11 is an enlarged sectional view of a main part of a disk substrate molding die apparatus for producing a disk substrate by injection molding according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk 2 Disk substrate 2a One main surface 2b The other main surface 3 Signal recording layer 4 Dielectric film 5 Protective film 11 Disk table 12 Mounting reference surface 13 Swelling portion 14 Centering member 15 Engagement hole 16 Center hole 71 Storage recess 17 Hub 21 Annular protrusion 22 Hub mounting surface 24 Magnet 25 Shear surface 31 Fixed mold 32 Movable mold 33 Mold 34 Molding cavity 42 Sprue bush 43 Resin injection passage 44 Annular notch 45 Recess 46 Synthetic resin Material 47 Tapered surface 48 Annular forming part 49 Annular convex part 50 Annular concave part 51 Stamper 53 Outer side stamper holder 63 Punching punch

Continuation of the front page (56) References JP-A-5-28539 (JP, A) JP-A-4-351726 (JP, A) JP-A-3-295622 (JP, A) JP-A-3-230381 (JP) JP-A-2-260144 (JP, A) JP-A-2-183480 (JP, A) JP-A-63-175277 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB G11B 7/24 G11B 7/26

Claims (5)

(57) [Claims] 1. A disk-shaped resin material having a light-transmitting property, a centrally located engaging hole with which a centering member of a disk rotation driving means is engaged, and a magnetic material surrounding the engaging hole. And a mounting portion having a hub storage recess in which the hub is housed and arranged, and a mounting reference surface for the disk rotation driving means. The hub is housed and arranged from the outer periphery of the engagement hole on the hub housing recess side. A disk substrate, wherein an annular protrusion protruding toward the side to be formed is integrally formed. 2. The disk substrate according to claim 1, wherein an inner peripheral surface of the projecting portion serves as a shearing portion on a tip side in a punching direction of a punching punch for punching the engagement hole. 3. A disk-shaped resin material having a light-transmitting property. An engaging hole in the center of which a centering member of a disk rotation driving means is engaged, and a magnetic material around the engaging hole. A disk substrate molding die apparatus for producing a disk substrate on which a mounting portion having a hub storage recess in which a hub is stored and arranged, and a mounting reference surface for the disk rotation driving means, is formed. A movable mold which is opposed to the fixed mold, is disposed so as to be able to approach and separate from the fixed mold, and forms a molding cavity between the fixed mold and the movable mold; Attached to at least one,
A stamper provided in the molding cavity, a sprue bush attached to one of the molds, and having a resin injection passage for guiding molten resin into the molding cavity; A hub storage recess forming portion for forming a hub storage recess in the above, and is disposed so as to be opposed to any one of the above-mentioned dies, and to be able to approach and separate toward any one of the above-mentioned dies, A punch for punching and forming an engagement hole of the disc substrate, wherein the hub is formed at an inner peripheral end of the hub storage recess forming portion from an outer periphery of the engagement hole on the hub storage recess side. An annular notch for forming a projection for forming an annular projection protruding toward the side where the storage substrate is arranged is formed. 4. The disk substrate molding die apparatus according to claim 3, wherein the inner peripheral surface of the projecting portion serves as a shearing portion of the punching punch at the front end in the punching direction. 5. The disk substrate forming die apparatus according to claim 3, wherein an inner side surface of the annular notch for forming the projection is tapered.