JPH0596581A - Formation of disk substrate for recording information signal - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] An information signal recording disk that enables stable rotation by positioning the disk on the disk table with high accuracy. A bottomed mounting reference hole having a mounting reference surface for restricting a mounting position with respect to a disk rotation driving means is formed, and then a through hole is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a disk substrate for an information signal recording disk on which information signals such as audio signals and video signals are recorded, and more particularly to a magneto-optical disk capable of re-recording information signals. The present invention relates to a method for forming an information recording disk substrate formed by molding a synthetic resin forming an information recording disk such as an optical disk and other optical disks.

[0002]

2. Description of the Related Art Conventionally, a magneto-optical disk has been proposed as an information signal recording disk on which information signals such as audio signals and video signals are recorded and which enables re-recording of information signals. This magneto-optical disk can record information signals such as digitized audio signals with extremely high density. Therefore, the applicant of the present application has made the diameter 64
It has been proposed a magneto-optical disk that can record an audio signal of at least 74 minutes.

As shown in FIG. 5, this magneto-optical disc 1 has a disc substrate 2 formed by molding a resin such as transparent polycarbonate resin, and a signal is provided on one main surface 2a side of the disc substrate 2. It is configured by forming a recording layer. The recording of the information signal on the magneto-optical disk 1 is performed by the light emitted from the optical head on a fine recording track provided on the signal recording layer in a state where the magneto-optical disk 1 is rotated at a predetermined rotation speed. This is performed by irradiating the beam and applying an external magnetic field that is magnetic field modulated according to the information signal to be recorded by the external magnetic field generator.

Since the magneto-optical disk 1 has a small diameter and fine recording tracks are formed at a high density, the magneto-optical disk 1 shown in FIG.
As shown in FIG. 3, the magneto-optical disc 1 is accurately positioned and mounted on the disc table 4 of the disc rotation drive device 3 provided in the recording / reproducing device for rotating the magneto-optical disc 1. It is necessary that the disk table 4 is integrally mounted and rotated in synchronization with the rotation of the disk table 4.

Therefore, the disc table 4 is provided at the center of the disc substrate 2 which constitutes the magneto-optical disc 1.
A center hole 6 is provided for engaging with a centering member 5 for centering the magneto-optical disk 1 mounted on the disk table 4 at the center of rotation. Also,
One main surface 2 on which the signal recording layer of the disk substrate 2 is formed
On the other main surface 2b side facing a, the mounting height position on the disk table 4 is accurately positioned, and the disk table 4 is rotated while maintaining the horizontal position accurately with respect to the center of rotation. A ring-shaped bulging portion 8 having a horizontal position mounting reference surface 7 formed on the front end surface is formed so as to surround the center hole 6.

A thin metal plate 9 is formed on the main surface 2a side of the disk substrate 2 so as to close the center hole 3.
Are arranged. The metal plate 9 is attracted by a magnet 10 arranged on the disc table 4 side, and the magneto-optical disc 1 mounted on the disc table 4 is integrated with the disc table 4. The center hole 3 is formed so as to penetrate in the thickness direction of the disk substrate 2 so that the magnetic flux of the magnet 10 arranged on the disk table 4 side can be transmitted to the metal plate 9 side.

The magneto-optical disk 1 configured as described above.
6, the center hole 6 is engaged with the centering member 5, and the horizontal position mounting reference surface 7 of the tip end surface of the bulging portion 8 is supported by the disk support surface 4a of the disk table 4, and The metal plate 9 is attracted by the magnet 10 and mounted on the disc table 4, so that the center of the disc table 4 coincides with the center of rotation of the disc table 4, the mounting position is positioned, and the disc is securely integrated. It can be mounted on the disc table 4. That is, in the magneto-optical disk 1, the outer peripheral surface 5 a of the centering member 5 formed so that the tip is reduced in diameter abuts and engages with the inner peripheral surface 6 a on the opening end side which is the mounting reference surface of the center hole 6. As a result, the disc table 4 is centered with respect to the center of rotation, and the mounting standard surface 7 is supported by the disc supporting surface 4a of the disc table 4, whereby the mounting height position is regulated and the disc table 4 is mounted on the disc table 4. It will be done.

[0008]

By the way, the disc substrate 2 constituting the magneto-optical disc 1 is formed in a molding cavity formed between a movable mold and a fixed mold constituting a mold device for molding the disc substrate. It is formed by injecting a synthetic resin such as a polycarbonate resin. The center hole 6 with which the centering member 5 engages
Is also formed in the mold device at the same time when the disk substrate 2 is molded.

That is, in the conventional mold apparatus, a punch for advancing and retracting is provided in the molding cavity by a hydraulic mechanism or the like, and a synthetic resin is injected into the molding cavity to mold the disk substrate 2 immediately after. The punching punch is moved to form the center hole 6.

When the punching punch is used to form the center hole 6 in the mold apparatus as described above, there is a problem in that burrs are easily generated in the advancing direction of the punching punch. In particular, the formation of the center hole 6 is performed in a molten state in which the synthetic resin injected into the molding cavity is not completely cured, so that the above-mentioned burr is significantly generated.

As shown in FIG. 7, such a burr 2c is formed on the inner peripheral surface 6a, which is the mounting reference surface of the center hole 6 with which the centering member 5 engages, and the mounting reference surface 7 of the tip end surface of the bulging portion 8. If it occurs, the circular accuracy of the center hole 6 will be deteriorated and smoothing of the mounting reference surface 7 will be hindered. As a result, the magneto-optical disk 1 cannot be accurately centered and accurately positioned, and cannot be mounted on the disk table 4.
Therefore, it becomes impossible to accurately maintain the horizontal state with respect to the center of rotation of the disk, and the recording or reproducing of the information signal may be defective.

Therefore, according to the present invention, when placed on a disc table, the inner peripheral surface portion of the center hole with which a centering member such as a centering member that achieves centering with respect to the center of rotation of the disc table engages, and It makes it possible to form a horizontal mounting reference surface with high accuracy on the disk table, and positions the disk with respect to the table table with high accuracy to ensure stable disk rotation, record information signals or The present invention has been proposed for the purpose of providing a method for forming a disk substrate that can form an information signal recording disk that does not cause a reproduction failure.

[0013]

In order to achieve the above-mentioned object, the present invention provides a method for forming an information signal recording disk substrate, which is formed by injecting a synthetic resin into a molding cavity of a mold device, After molding a bottomed mounting reference hole having a mounting reference surface for controlling the mounting position with respect to the disk rotation driving means on at least a part of the inner peripheral surface, at least a part of the mounting reference hole is projected into the molding cavity. The movable member is punched to form a through hole.

[0014]

According to the method of forming the disc substrate for recording the information signal of the present invention, the bottomed mounting reference hole having the mounting reference surface for controlling the mounting position with respect to the disc rotation driving means is formed at the time of molding the disc substrate, Since at least a part of the wearing standard hole is punched by the movable member to form the through hole, the through hole can be formed without affecting the mounting standard surface of the mounting standard hole.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A disk substrate forming method according to the present invention will be described below in the order of steps with reference to the drawings. In the method according to the present invention, first, a disk substrate 11 having a disk shape as shown in FIG. 1 is molded using a mold device for molding a disk substrate.

The disc substrate 11 is formed by molding, for example, a transparent polycarbonate resin having a good light transmission property, and one main surface 11a is coated with a magneto-optical recording medium constituting a magneto-optical disc. The signal recording layer is formed. On one main surface 11a side on which the signal recording layer is formed, prepits forming a recording track are formed by a stamper arranged in the mold device at the same time when the disk substrate 11 is molded.

The main surface 1a of the disk substrate 11 on which the signal recording layer is formed and the other main surface 1 opposite to the main surface 1a are formed.
The 1b side is a signal reading surface on which the light beam emitted from the optical head is irradiated when the signal recording layer is formed on the one main surface 11a to form a magneto-optical disk.

The mounting height position on the disk table 4 is positioned on the other main surface 11b side facing the one main surface 11a on which the signal recording layer of the disk substrate 11 is formed. , Above disk table 4
A ring-shaped swelling portion 13 having a horizontal position mounting reference surface 12 for positioning the horizontal state with respect to the rotation center of the
Is formed by projecting.

In addition, in the center of the disk substrate 11, a center with a bottom is provided from the tip end surface side of the ring-shaped bulging portion 13 where the horizontal position mounting reference surface 12 is formed to a middle portion in the thickness direction. The hole 14 is formed. This center hole 1
Reference numeral 4 denotes a centering member 5 arranged on the disk table 4 when the disk substrate 11 is configured as a magneto-optical disk and mounted on the disk table 4, like the center hole provided on the disk substrate. In addition, it has a function of centering the rotation center of the disk table 4. Therefore, as the centering member 5 is engaged, the inner peripheral surface 14a continuous with the horizontal position mounting reference surface 12 of the tip end surface of the bulging portion 13 of the center hole 14 with which the outer peripheral surface 5a of the centering member 5 abuts,
It serves as a mounting reference surface for the disc table 4.

The center hole 14 is formed with a depth D sufficient for the centering member 5 to achieve the centering function and engage when the magneto-optical disk is mounted on the disk table 4.

Further, one main surface 1 of the disk substrate 11
When a magneto-optical disk is constructed by using the disk substrate 11 in the central portion on the side of 1a, a metal plate is arranged so that the metal plate is attracted by the magnet 10 arranged on the disk table 4 side and fitted. The mounting recess 15 is molded.

The disk substrate 11 constructed as described above
Is molded using the molding die device 20 configured as shown in FIG. This mold device 20 includes a fixed mold 21.
And a movable mold 22, and a molding cavity 23 for molding the disk substrate 11 is defined between the fixed mold 21 and the movable mold 22.

A sprue bush 24, which is located at the center of the molding cavity 23 and allows the molten polycarbonate resin supplied from the injection molding machine to flow into the molding cavity 23, is disposed on the fixed mold 21 side. It is set up. And the melted polycarbonate resin is
The resin is introduced into the molding cavity 23 through a resin inlet 25 formed in the sprue bush 24.

The tip end side of the sprue bush 24 is further extended from the tip end portion of an inner peripheral side stamper retainer 27, which will be described later, which forms the metal plate mounting recess 15 formed on the one main surface 11a side of the disk substrate 11. Molding cavity 23
It is projected inside.

Further, a stamper 26 for molding pre-pits forming recording tracks is provided on the surface of the fixed mold 21 on the side forming the molding cavity 23. The stamper 26 is attached to the fixed mold 21 while being supported by stamper retainers 27 and 28 on the inner peripheral side and the outer peripheral side, respectively. An inner peripheral side stamper retainer 27 that supports the inner peripheral side of the stamper 26 is fitted and attached to a stamper retainer support body 29 that is fitted and disposed in the sprue bush 24, and an outer periphery that supports the outer peripheral side of the stamper 26. The side stamper retainer 28 is fitted and attached to the outer peripheral side of the fixed mold 21.

The tip side of the inner-side stamper retainer 27 is projected into the molding cavity 23 so as to mold the metal plate mounting recess 15 formed on the one main surface 11a side of the disk substrate 11. ing.

On the other hand, on the side of the movable mold 22 which is arranged so as to face the fixed mold 21, there is a bulging portion molding portion 30 for molding a ring-shaped bulging portion 13 having the mounting reference surface 12 at the tip surface. A center hole forming fixing member 31 for forming the center hole 14 is formed so as to project to a midway portion in the forming cavity 23.

On the movable mold 22 side, a through hole is formed by punching out a through hole 17 at the bottom 16 of the center hole 14 formed so as to be located at the center of the center hole forming fixing member 31. A movable member 32 for use is disposed. As shown in FIG. 2, the movable member 32 has a diameter smaller than that of the center hole forming fixing member 31, and is arranged so as to further project from the tip end side of the center hole forming fixing member 31 into the forming cavity 23. It is set up.

By forming and arranging the movable member 32 in this manner, the inner peripheral surface 14a, which is the mounting reference surface of the center hole 14 formed in the center hole forming fixed member 31, is affected. It can be moved without.

Then, in the method of the present invention, the molten polycarbonate resin supplied from the injection molding machine via the sprue bush 24 is injected into the molding cavity 23 of the mold device 20 configured as described above. Then, the disk substrate 1 having the bottomed center hole 14 as shown in FIG.
Mold 1. When the disk substrate 11 is molded, as shown in FIG. 3, the movable member 32 arranged on the movable mold 22 side is projected to the fixed mold 21 side by operating a movable means such as a hydraulic mechanism. By projecting the movable member 32 in this manner, the through hole 17 is formed in the bottom portion 16 of the center hole 14.

When the movable member 32 is projected so as to form the through hole 17, the tip of the movable member 32 projects from the molding cavity 23 and the sprue bush 24 disposed on the fixed mold 21 side. The sprue bush 24 is brought into contact with the tip of the molding cavity 2 as shown in FIG.
Move in the direction to exit from 3. Further, the movable member 32 is retracted to the position shown in FIG. 2 after forming the through hole 17.

The disk substrate 11 having the through holes 17 formed therein as described above is cured in the mold device 20 and then taken out from the molding cavity 23, as shown in FIG. A disk substrate 11 is formed, which is a material for various magneto-optical disks.

Although the method of forming the disk substrate applied to the magneto-optical disk has been described in the above embodiment, the method of the present invention has the center hole and the main surface of the disk substrate is connected to the disk table. It can be widely applied to a disc having a mounting reference surface and a centering surface for the disc table.

Since the disk substrate 11 formed in the above embodiment is applied to a magneto-optical disk provided with a metal plate for magnet clamp, the through hole 17 is formed in the disk substrate. When the magneto-optical disk is constructed by using 11, the magnetic disk of the magnet arranged on the disk table side has a function of transmitting the magnetic flux.

Further, the through hole 17 of the disc substrate 11 formed by the method of the present invention is formed by the disc substrate 11
When a disc for recording an information signal is manufactured by using, it can be used as a portion with which a gripping mechanism for transportation during the manufacturing process is engaged.

[0036]

As described above, according to the method of the present invention, the center hole having the mounting reference surface is formed, and then the movable member is operated to form the through hole. The through hole can be formed without affecting the hole. Therefore, it is possible to form a disk substrate having a mounting reference surface formed with high accuracy without generating burrs or the like around the center hole.

Since the information signal recording disk constructed by using this disk substrate can be accurately positioned and mounted on the disk table, stable rotation of the disk can be guaranteed to record or record the information signal. Recording and reproduction can be realized for the information signal while maintaining good recording and reproduction characteristics without causing reproduction failure.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a disk substrate molded by the method of the present invention.

FIG. 2 is a cross-sectional view of a mold device showing a state where a synthetic resin is injected into the mold device to mold a disk substrate.

FIG. 3 is a cross-sectional view of the mold device showing a state in which a through hole is formed in a disc substrate molded by the mold device.

FIG. 4 is a sectional view of a disk substrate formed by the method of the present invention.

FIG. 5 is a partially cutaway perspective view of a conventional magneto-optical disk.

FIG. 6 is a sectional view showing a state in which a conventional magneto-optical disk is mounted on a disk table.

FIG. 7 is a partial cross-sectional view showing an enlarged part around a center hole of a conventional magneto-optical disk.

[Explanation of symbols]

 11 Disk Substrate 14 Center Hole 16 Bottom of Center Hole 17 Through Hole 20 Mold Device 21 Fixed Mold 22 Movable Mold 23 Molding Cavity

Claims (1)

[Claims] 1. A method of forming an information signal recording disk substrate formed by injecting a synthetic resin into a molding cavity of a mold device, wherein a mounting position for a disk rotation driving means is provided on at least a part of an inner peripheral surface. Information signal recording for forming a through hole by molding a bottomed center hole having a mounting reference surface to be regulated and then punching out at least a part of the mounting reference hole with a movable member protruding into the molding cavity. A method for forming a disk substrate.