JPH0531721Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a disk hub that is attached to the center of an optical disk that is attached to a magnetic clamp type disk rotation drive device and rotated.

B. Prior Art Optical disks have been known as recording media for various information signals.

As a disk rotation drive device for rotating this optical disk, a device using a magnetic clamp method is used. A disk rotation drive device that uses this magnetic clamp method places a magnet on the disk table, and uses this magnet to magnetically attract a disk hub, which has a magnetic metal plate attached to the center of the optical disk, to transfer the optical disk. The disk is integrated with the disk table and is configured to be rotated.

Incidentally, as optical disks, optical disks mainly composed of a disk substrate made of synthetic resin are widely used.

Therefore, an optical disk mounted on a disk rotation drive device that employs a magnetic clamp system has a ring-shaped member made of the same synthetic resin as the disk substrate made of the synthetic resin described above as a disk hub attached to the center of the optical disk. By using a structure in which a metal plate is attached to the disk substrate, the disk substrate and the disk hub are firmly welded together.

That is, as shown in FIG. 4, the disk hub 50 attached to the center of this optical disk is
It consists of a metal plate 52 in which a center hole 51 is drilled into which the center spindle of the disk rotation drive device engages, and a ring-shaped member 53 made of synthetic resin of the same quality as the disk substrate. When molding the member 53, a joining part 56 formed on the outer peripheral edge of the metal plate 52 via the stepped part 54 is integrally formed by insert or outsert resin molding. The ring-shaped member 53 has a main body of the metal plate 52 on the opposite side of the ring-shaped member 53 to the disk table in order to make it easier for the magnet provided on the disk table of the disk rotation drive device to magnetically attract the metal plate 52. The surface portion 52a is attached so as to be substantially flush with each other. Further, a welding rib 55 is provided on the side of the ring-shaped member 53 facing the disk, and the ring-shaped member is welded to the center of the disk substrate by a welding method such as ultrasonic welding. is attached to a disk substrate to form an optical disk.

C. Problems to be solved by the invention However, the ring-shaped member and the metal plate constituting the disk hub have significantly different thermal shrinkage rates.

Further, the disk hub requires a certain thickness in order to allow the metal plate to closely oppose the magnet disposed within the disk table of the disk rotation drive device. Therefore, the metal plate is attached to a biased position on the side of the ring-shaped member opposite to the disk table, so that the magnet of the disk table can easily attract the metal plate. Therefore, when forming a disk hub by integrally forming the ring-shaped member with a metal plate by resin molding such as an outsert or an insert, the difference in thermal shrinkage rate between the metal plate and the ring-shaped member, etc. As a result, shrinkage may occur in the inner radial direction on the side of the ring-shaped member facing the disk substrate, and the metal plate may be attached to the ring-shaped member in a deformed manner as shown in FIG.

In an optical disk to which a disk hub having a metal plate deformed in this way is attached, when it is mounted on the disk table of the disk rotation drive device,
Due to the magnets placed on the disk table, it is no longer possible to apply a uniform suction force over a certain period of time without bias.

Furthermore, a disk hub is constructed by integrating an optical disk using a disk substrate made of synthetic resin as described above with a metal plate having a heat shrinkage rate significantly different from that of synthetic resin by molding it into a ring-shaped member made of synthetic resin. When welding the disk hub to the disk substrate using the welding ribs described above by a welding method such as ultrasonic welding, there is a significant difference in thermal shrinkage between the synthetic resin ring-shaped member and the metal plate. There is also the possibility that extra stress will be generated inside the disk substrate.

When stress is generated inside the disk substrate in this way, distortion occurs within the disk substrate, which causes birefringence when a laser beam is irradiated, resulting in insufficient irradiation of the laser beam to a predetermined recording track. Not only does it become impossible to perform irradiation, but it also becomes impossible to reflect the return beam from a predetermined recording track onto a predetermined optical path, resulting in errors in writing and reading information signals.

Therefore, the present invention was devised for the purpose of preventing the deformation of the disk substrate caused by the difference in heat shrinkage rate between the metal plate and the ring-shaped member as described above when integrally molding the metal plate into the ring-shaped member. It is what was done.

D. Means for Solving the Problems In order to solve the above problems and achieve the above objects, the present invention includes a ring-shaped member made of synthetic resin that is welded to the center of the disk substrate of an optical disk;
In the disk hub of the optical disk, which is composed of a metal plate for a magnetic clamp that is integrally attached to this ring-shaped member, the metal plate has resin insertion holes drilled at equal intervals at positions on a concentric circle from the center. The ring-shaped member, which has a hole formed therein and is formed integrally with the metal plate by resin molding, has an outer peripheral side that covers the outer peripheral part of the metal plate, and a connecting part that is inserted through the resin insertion hole. It consists of an outer circumferential side and an inner circumferential side connected to each other, and a welding rib is provided on the inner circumferential side that is welded to the disk substrate. An annular slit is formed between the periphery and the periphery.

F Effect This invention aims to reduce the difference in thermal contraction rate between the metal plate and the ring-shaped member when attaching and molding the metal plate to the ring-shaped member and when fixing this disk hub to the disk substrate. It can be absorbed through the slit.

G. Embodiments Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The disk hub 1 of the optical disk according to the present invention includes:
As shown in FIGS. 1 to 3, there is a magnetic metal plate 2 that is magnetically attracted to the magnet in the disk table of the disk rotation drive device, and a ring-shaped member 3 for attaching the metal plate 2 to the disk substrate. It consists of.

The metal plate 2 is formed by punching out a thin metal original plate of magnetic material into a disk shape, and has a spindle hole in the center of its main surface portion 2a, into which the center spindle of the disk rotation drive device engages. 4 is drilled. Further, on the outer peripheral side of the metal plate 2, an annular joint portion 6 is provided via a stepped portion 5 formed in a half-opened state by, for example, step processing. As shown in FIG. 2, a resin insertion hole 7 for integrally attaching the metal plate 2 to the ring-shaped member 3 when the ring-shaped member 3, which will be described later, is molded into the joint portion 6 is provided in this joint portion 6. A plurality of holes are drilled at equal intervals on concentric circles from the center of the metal plate 2. Furthermore, at least the surface of the main surface portion 2a in which the spindle hole 4 is formed, which faces the disk table of the disk rotation drive device, is such that the optical disk to which the disk hub 1 having the metal plate 2 is mounted is mounted on the disk table. The disk table is formed with a highly precise flat surface so that when the magnet is placed on the disk table, the magnet disposed on the disk table will be attracted to the disk table with uniform suction force for a certain period of time without bias. .

Next, the metal plate 2 is attached, and
The ring-shaped member 3 fixed to the disk substrate is molded from the same synthetic resin as the disk substrate in order to suppress distortion during welding to the disk substrate and to be firmly attached to the substrate.

This ring-shaped member 3 includes an outer peripheral side portion 8 that covers the joint portion 6 formed on the outer peripheral side of the metal plate 2;
It consists of an inner peripheral side part 9 on which the joint part 6 of the metal plate 2 is placed and is fixed to the center of the disk substrate.

The inner circumferential side portion 9 has a certain thickness in order to allow the metal plate 2, which is integrally attached to the ring-shaped member 3, to closely face the magnet provided on the disk table of the disk rotation drive device. It is molded. The outer circumferential side portion 8 formed on the inner circumferential side portion 9 through the resin insertion hole 7 of the metal plate 2 is located on the opposite side of the disk table to the metal plate 2.
The metal plate 2 is placed so that the main surface portion 2a of the metal plate 2 is substantially flush with the
It is formed to have a thickness that is substantially the same as that of the stepped portion 5, and covers the outer circumferential side of the joint portion 6 of the metal plate 2 to form the outer circumferential shape of the disk hub 1. This is to make it easier for the metal plate 2 to be magnetically attracted by the magnet of the disk table.

Further, a welding rib 10 is provided on the surface of the inner peripheral side portion 9 facing the disk substrate. This welding rib 10 is provided to enable strong welding by concentrating ultrasonic waves during ultrasonic welding. A slit 11 is formed between the inner peripheral part of the outer peripheral side part 8 and the outer peripheral part of the inner peripheral side part 8.

Therefore, the outer circumferential side part 8 and the inner circumferential side part 9 of the ring-shaped member 3 are respectively divided by the annular slit 11 through the metal plate 2, as shown in FIGS. 1 and 3. The outer peripheral side part 8 and the inner peripheral side part 9 are connected by a connecting part 12 that passes through the resin insertion hole 7 of the metal plate 2, and by sandwiching the joint part 6 of the metal plate 2, A disk hub 1 is constructed by molding a ring-shaped member 3 to which a metal plate 2 is integrally attached.

Since the outer circumferential side part 8 and the inner circumferential side part 9 are thus divided by the slit 11, thermal contraction of the inner circumferential side part 9 is prevented from being transmitted to the outer circumferential side part 8. That is, the shrinkage in the inner circumferential direction due to thermal contraction of the inner circumferential side portion 9 no longer acts as a tensile force that pulls the outer circumferential side portion 8 in the inner circumferential direction. Therefore, at the slit 11, the thermal contraction rate between the outer peripheral side part 8 and the inner peripheral side part 9 of the ring-shaped member 2 is divided, and the difference in the thermal contraction rate between the metal plate 2 and the ring-shaped member 3 is alleviated. It will be absorbed.

Therefore, when molding the disk hub 1, due to the difference in heat shrinkage rate, the metal plate 51 as shown in FIG. Prevented. As a result, according to the present invention, the metal plate 2 can be attached to the ring-shaped member 3 while maintaining its flatness with high precision.

Further, since a welding rib 10 is provided on the inner peripheral side 9 of the ring-shaped member 3 on the side facing the disk substrate, the welding rib 10 is brought into contact with the center of the main surface of the disk substrate. By welding using a welding method such as ultrasonic welding, the disk hub 1
is firmly attached to a disk substrate to form an optical disk.

Also, when welding the disk hub 1 to the disk substrate, the annular slit 10 can absorb the distortion caused by the difference in thermal contraction rate between the metal plate 2 and the ring-shaped member 3 of the disk hub 1. This also eliminates the generation of extra stress inside the disk substrate.

Therefore, even if the disk hub 1 configured as described above is welded to the disk substrate, no extra stress is generated inside the disk substrate, so no distortion is caused in the disk substrate. This eliminates the possibility of birefringence occurring when a laser beam is irradiated. Therefore, a sufficient laser beam can be irradiated onto a predetermined recording track, and a return beam from the predetermined recording track can be reflected onto a predetermined optical path, thereby preventing errors in writing and reading information signals.

G. Effects of the invention According to the invention, when attaching a metal plate to a ring-shaped member to form a disk hub, and when fixing this disk hub to a disk substrate, the difference in thermal contraction rate between the metal plate and the ring-shaped member is reduced. Since it can be absorbed by the annular slit of the ring-shaped member,
To provide a disk hub attached to a ring-shaped member while maintaining the flatness of a metal plate with high precision, and to avoid generating extra stress in the disk substrate when the disk hub is fixed to the disk substrate.

Therefore, since the flatness of the metal plate is maintained in the optical disk to which the disk hub according to the present invention is attached, when it is mounted on the disk table of the disk rotation drive device, the magnet placed on the disk table This allows for uniform suction power for a certain period of time without bias.
Additionally, since no extra stress is generated inside the disk substrate, birefringence does not occur when a laser beam is irradiated, and sufficient laser beam irradiation can be performed on a predetermined recording track. , the return beam from a predetermined recording track can be reflected to a predetermined optical path, and errors in writing and reading information signals can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view showing a disk hub of an optical disk according to the present invention, FIG. 2 is a plan view of the disk hub of the present invention, and FIG. 3 is a bottom view thereof. FIG. 4 is a cross-sectional side view showing a conventional disk hub, and FIG. 5 is a cross-sectional side view showing a state in which the conventional disk hub is deformed due to the difference in thermal contraction rate between the metal plate and the ring-shaped member. . DESCRIPTION OF SYMBOLS 1... Disk hub, 2... Metal plate, 3... Ring-shaped member, 6... Joint part, 7... Resin insertion hole,
8... Outer circumferential side part, 9... Inner circumferential side part, 10... Welding rib, 11... Annular slit.

Claims (1)

[Claims for Utility Model Registration] An optical disk consisting of a ring-shaped member made of synthetic resin that is welded to the center of the disk substrate of the optical disk, and a metal plate for a magnetic clamp that is integrally attached to this ring-shaped member. In the disk hub, resin insertion holes are formed in the metal plate at equal intervals on a concentric circle from the center, and the ring is formed integrally with the metal plate by resin molding. The shaped member is made up of an outer circumferential side portion that covers the outer circumferential portion of the metal plate, and an inner circumferential side portion that is connected to the outer circumferential side via a connecting portion that is inserted through the resin insertion hole, and is welded to the disk substrate. 1. A disk hub for an optical disk, wherein a welding rib is provided on an inner circumferential side, and an annular slit is formed between an outer circumferential portion of the inner circumferential side and an inner circumferential portion of the outer circumferential side.