JPH0589529A - Production of optical disk - Google Patents

Abstract

PURPOSE:To assure the strength to mount a disk hub and to shorten the time for mounting by executing both of ultrasonic welding and adhesion by a UV curing resin at the time of mounting the disk hub to the central part of a transparent substrate. CONSTITUTION:A light source 10 is disposed on a transparent substrate 2 side and the part coated with the UV curing resin 11 is irradiated with UV rays, by which the disk hub 5 and the transparent substrate 2 are eventually adhered. The disk hub 5 is mounted to the front end of a welding horn 3 of an ultrasonic welding device and the welding horn 3 is adjusted in position relative to the transparent substrate 2; thereafter, the horn is lowered until a rib 8 comes into contact with the transparent substrate 2. The welding horn 3 is operated to impress ultrasonic vertical vibrations where the rib 8 comes into contact with the substrate. The rib 8 and the transparent substrate 2 are thereby so welded that the disk hub 5 attains a prescribed height with the transparent substrate 2. The light source 10 is disposed in the part coated with the UV curing resin 11 after the ultrasonic welding. The resin is irradiated with the UV rays, by which the disk hub and the transparent substrate are adhered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk, and more particularly to an improvement in a mounting method for mounting a hub on the center of a transparent substrate.

[0002]

2. Description of the Related Art Optical discs represented by so-called CD-ROMs, digital audio discs, magneto-optical discs, etc. generally have a signal recording layer and a reflective film formed on a transparent substrate made of polycarbonate, acrylic resin or the like. It is configured by forming a hard protective film on this. And in this kind of optical disc, normally,
A disk-shaped disk hub at the center of the transparent substrate is attached, and the disk hub is magnetically attracted onto a disk table fixed to the tip of the spindle shaft of the recording / reproducing device so that it can be rotated together with the disk table. There is.

The disk hub serves to magnetically attract the optical disk to the disk table and to align the center of rotation of the optical disk with the center of rotation of the spindle shaft. Such a disc hub includes, for example, a disc-shaped metal plate magnetically attracted to a disc table and a disc-shaped fixed portion attached to an optical disc substrate which is a transparent substrate. The fixing portion is usually made of resin or the like in consideration of weight saving of the hub and adhesion to the substrate.

[0004]

By the way, several methods have been conventionally proposed as a method for attaching the above-mentioned disk hub to the central portion of the transparent substrate.

For example, a welding method using ultrasonic waves is known as one of them. In this ultrasonic welding method,
For example, as shown in FIG. 12, as the disc hub 71 to be attached, one having a rib 74 provided along the outer periphery of the substrate attaching surface 72a of the fixing portion 72 is used. And
At the time of welding, the disk hub 71 is placed on the transparent substrate 75 so that the rib 74 contacts the disk hub welding portion of the transparent substrate 75, and ultrasonic longitudinal vibration is applied to the disk hub 71. As a result, the contact portion between the transparent substrate 75 and the rib 74 is melted, and the disk hub 7 is removed from the transparent substrate 75.
1 will be fixed.

However, this method has a drawback in that sufficient adhesive strength cannot be obtained because the adhesive area is small. Therefore, in order to increase the adhesive strength, it has been considered to secure the adhesive area by increasing the size of the ribs, but increasing the size of the ribs stresses the substrate and reduces the strength of the disc substrate itself. It causes inconvenience such as decrease.

As another mounting method, a method using an ultraviolet curable resin has been proposed. In this method, an ultraviolet curable resin is applied to the entire surface of the disk substrate on which the disk hub is mounted to bond the disk hub, and the bonding area is large and sufficient bonding strength can be obtained.

However, in the case of bonding with an ultraviolet curable resin, generally, the objects to be adhered are superposed on each other via the ultraviolet curable resin, and then temporary curing is carried out, and then main curing is carried out. Takes time. In particular, if an ultraviolet curable resin is applied and adhered to the entire surface on which the disk hub is placed, it takes a considerable amount of time for curing and sufficient productivity cannot be obtained. In addition, since the uncured portion of the ultraviolet curable resin is likely to be generated due to some trouble, the adhesion is likely to be insufficient and the reliability is low.

Further, as another method, there is known a method of adhering by heat welding as shown in, for example, Japanese Patent Laid-Open No. 62-192946, but there is a concern that the optical characteristics of the disk substrate may deteriorate. There is no suitable method.

Therefore, the present invention has been proposed in view of such a conventional situation, and it is possible to mount an optical disk hub with high adhesive strength for a single time, and to manufacture an optical disk having high mechanical strength. The purpose is to provide a method.

[0011]

In order to achieve the above-mentioned object, the method of manufacturing an optical disk of the present invention uses ultrasonic welding when attaching a disk hub to the center of a transparent substrate on which a signal recording layer is formed. It is characterized in that both the adhesion by the ultraviolet curing resin is performed.

[0012]

[Operation] When the disk hub is attached to the center of the transparent substrate by both ultrasonic welding and adhesion with UV curable resin, the mounting strength of the disk hub is improved compared to the case where the disk hub is attached only by ultrasonic welding. To do. Further, in this case, the ultraviolet curable resin can provide sufficient attachment strength if it is applied only to the outside of the ultrasonically welded portion, so that the adhesive area can be reduced and the time required for curing can be shortened. Moreover, by using ultrasonic welding and adhesion using an ultraviolet curable resin together, sufficient strength can be secured and reliability is improved even if either mounting state is insufficient.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing an optical disk to which the present invention is applied will be described below with reference to the drawings.

To manufacture an optical disk, first, the concavo-convex pattern formed on the stamper is transferred onto the transparent substrate. The transfer method may be any of a compression method, an injection method, an injection compression method, a photopolymer method (so-called 2P method), and the like. Further, the material of the transparent substrate is not particularly limited, and any commonly used substrate material such as acrylic resin and polycarbonate resin may be used.

Further, the disc substrate on which the concavo-convex pattern is transferred is provided with a signal recording layer, a reflection film, a protective layer and the like, but the optical disc may have any constitution, and therefore the film is formed on the disc substrate. The reflective film, the signal recording layer, the protective film, etc. to be formed can be arbitrarily selected according to the application. For example, in a digital audio disc, a so-called CD-ROM, or the like, a metal reflective film such as Al is formed on a disc substrate on which the concavo-convex pattern is transferred. In a magneto-optical disk, a perpendicular magnetization film having magneto-optical characteristics (Kerr effect and Faraday effect) is formed. In addition, it can be applied to an optical disk having a signal recording layer such as a low melting point metal thin film, a phase change film, and a film containing an organic dye.

After the desired signal recording layer, protective film, etc. are formed on the transparent substrate in this way, a disk hub is attached to the center of the transparent substrate. Here, the mounting of the disc hub is
In order to secure the mounting strength, shorten the bonding time, and obtain the mechanical strength of the optical disk itself, both welding by ultrasonic waves and bonding by an ultraviolet curable resin are performed. At this time, the process sequence may be such that ultrasonic bonding is first performed and then bonding with an ultraviolet curable resin is performed, or the ultraviolet curable resin is previously applied to the disk hub bonding portion of the transparent substrate and then the Ultrasonic welding may be performed, and after the ultrasonic welding, the ultraviolet curable resin may be cured for adhesion.

First, in order to attach the disk hub by the former method, as shown in FIG. 1, the transparent substrate 2 is placed and fixed on the turntable 1 on the surface of which suction means such as a double-sided tape is provided. .. Then, the disc hub 5 is attached to the tip of the welding horn 3 of the ultrasonic welding device provided with the vertically movable welding horn 3. The disc hub 5
Is composed of a disk-shaped metal plate 6 magnetically adsorbed on the disk table, and a disk-shaped fixed portion 7 made of resin and welded to the transparent substrate 2, and the fixed portion 7 is a substrate welded to the transparent substrate 2. Ribs 8 are provided along the outer periphery of the mounting surface 7a. The metal plate 6 is attached to the tip of the welding horn 3.

After attaching the disk hub 5 to the tip of the welding horn 3 as described above, the position of the welding horn 3 is adjusted with respect to the transparent substrate 2, and the rib 8 contacts the transparent substrate 2 as shown in FIG. Lower until When the rib 8 contacts the transparent substrate 2, the welding horn 3 is operated to apply ultrasonic longitudinal vibration to the disk hub 5. Then, as shown in FIG. 3, since the contact portion between the transparent substrate 2 and the rib 8 is melted, the position of the substrate mounting surface 7a before welding,
The application of ultrasonic waves is stopped when the total welding depth TD, which is defined by the distance from the position of the mounting surface 7a after welding, reaches a predetermined value. As a result, the disc hub 5 is attached to the transparent substrate 2 with a predetermined height.
Then, the disc hub is removed from the tip of the welding horn 3 to raise the welding horn 3.

After the ultrasonic welding is performed in this manner, the ultraviolet ray curable resin is further adhered to further secure the attachment of the disc hub. Here, it is almost meaningless to bond the hub with the ultraviolet curable resin even if the inside of the rib is bonded, and by bonding the outside of the rib, the mounting strength can be significantly improved. Therefore, in the present embodiment, as will be described below, the hub mounting strength is secured and the mounting time is shortened by applying and curing the ultraviolet curable resin only on the outer side of the rib.

That is, as shown in FIG. 4, the transparent substrate 2
The turntable 1 on which is mounted is inclined, and the UV curable resin supply port 9 is set to the circumference of the disc hub 5 so that the UV curable resin is applied to the gap between the ultrasonically welded disc hub 5 and the transparent substrate 2. Place in the vicinity. Then, while rotating the turntable 1 in one direction, the ultraviolet curable resin 11 is supplied from the ultraviolet curable resin supply port 9. As a result, the ultraviolet curable resin 11 flows into the gap between the disk hub 5 and the transparent substrate 2 and is applied to the portion outside the rib 8. Then, as shown in FIG. 5, by arranging the light source 10 on the transparent substrate 2 side and irradiating the portion coated with the ultraviolet curable resin 11 with ultraviolet rays, the disc hub 5 and the transparent substrate 2 are bonded together. Becomes

Next, the latter method, that is, the method of mounting the hub in the order of application of the ultraviolet curable resin, ultrasonic welding, and curing of the ultraviolet curable resin will be described.

First, as shown in FIG. 6, the transparent substrate 2 is placed and fixed on the turntable 1 on the surface of which the suction means is provided as in the case described above. And this transparent substrate 2
The UV-curable resin supply port 9 is arranged so that the UV-curable resin is applied along the outer circumference of the upper disk hub mounting portion, and the UV-curable resin 11 is applied while rotating the turntable 1 in one direction. Then, as shown in FIG. 7, the disc hub 5 is attached to the tip of the welding horn 3 of the ultrasonic welding apparatus, and the position of the welding horn 3 is adjusted with respect to the transparent substrate 2. Then, as shown in FIG. Is lowered until it contacts the transparent substrate 2. Where the ribs 8 make contact,
The welding horn 3 is operated to apply ultrasonic longitudinal vibration, and the rib 8 and the transparent substrate 2 are welded to the transparent substrate 2 so that the disk hub 5 has a predetermined height. In addition,
At this time, since there is a possibility that the applied ultraviolet curable resin 11 may be scattered by the ultrasonic longitudinal vibration, the resin is prevented from being scattered by providing a mask in advance on the outer periphery of the portion to which the ultraviolet curable resin is applied. Then, after ultrasonic welding, the light source 10 is arranged on the portion coated with the ultraviolet curable resin 11 as shown in FIG. 9 and ultraviolet rays are irradiated to bond the disc hub and the transparent substrate.

When the ultrasonic welding and the adhesion using the ultraviolet curable resin are used together in this way, the mounting strength is improved as compared with the case where only the ultrasonic welding is used. In addition, when the ultrasonic welding and the adhesion by the ultraviolet curable resin are used together, the ultraviolet curable resin is
As described above, it is sufficient to apply only to the outer side of the ribs, and the adhesion area is small, so that the curing time does not take so long, and the increase in attachment time can be suppressed. In addition, if the mounting is performed by both ultrasonic welding and bonding with an ultraviolet curable resin, sufficient strength (10 kg weight or more) can be secured even if either mounting state is insufficient, so that reliability is improved. Hope to improve.

It should be noted that such an effect can be obtained to the same degree when either of the above two methods is adopted, but the transparent substrate 2
When the ultraviolet curable resin 11 is previously applied on top and ultrasonic welding is performed thereafter, the applied ultraviolet curable resin 11 leaks due to ultrasonic vibration as described above. It is necessary to provide a mask on the outer periphery of the portion where the cured resin 11 is applied, and the operation becomes complicated accordingly. Therefore, from the viewpoint of simplifying the work operation and shortening the work time, it is more advantageous to carry out the adhesion by the ultraviolet curable resin after the ultrasonic welding.

Next, in order to examine the mechanical strength of the optical discs manufactured as described above, various optical discs (disc 1, disc 2, comparison Disk 1 and comparative disk 2) were prepared and the hub breaking strengths were compared.

[0026]

[Table 1]

The hub breaking strength was measured as follows. To measure the hub breaking strength, first, refer to FIG.
The optical disk 52 is mounted on the disk receiving stand 51 as shown in FIG. The disc pedestal 51 is a cylindrical body having an outer diameter slightly larger than the outer diameter of the disc hub 54, and a circular recess 51a along the outer periphery of the cylinder on one end surface on which the optical disc 52 is placed. Is provided, and the circumference of the hub mounting portion of the mounted optical disk 52 is supported in a ring shape. Then, the optical disk 52 is placed on such a disk receiving base 51, and the load cell 53 is loaded with various weights from the top toward the hub mounting portion.
To lower. Then, the hub breaking strength was evaluated by measuring the weight of the load cell 53 required to break the optical disk 52. The number of samples measured is 10 for each optical disc. Figure 1 shows the measurement results
Shown in 1.

As can be seen from FIG. 11, in the disk 1 and the disk 2 to which the disk hub was attached by using both the bonding by the ultraviolet curing resin and the ultrasonic welding, the weight required to break the disk was 60 to 80 kg. ,
While the hub breaking strength is high, the comparative disk 1 having the disk hub attached only by the UV curable resin bonding and the comparative disk 2 having the disk hub attached only by ultrasonic welding have a low hub breaking strength. Therefore, from this fact, it is not possible to attach the disc hub by both means of ultrasonic welding and adhesion with an ultraviolet curable resin.
It was confirmed that it is effective in securing the mounting strength of the disk hub and obtaining an optical disk having high mechanical strength.

[0029]

As is apparent from the above description, in the method of manufacturing an optical disk of the present invention, both ultrasonic welding and adhesion by the ultraviolet curable resin are used when the disk hub is attached to the central portion of the transparent substrate. Since this is done, it is possible to secure the mounting strength of the disk hub, shorten the mounting time, and improve the mechanical strength of the optical disk. Moreover, if ultrasonic welding and welding using an ultraviolet curable resin are used together, a certain degree of strength can be secured even if one of the mounting states is insufficient, so that reliability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing a step of attaching a welding horn to a disc hub in an example of a manufacturing method to which the present invention is applied.

FIG. 2 is a schematic diagram showing an ultrasonic wave applying step in an example of a manufacturing method to which the present invention is applied.

FIG. 3 is a schematic view showing a state of ribs ultrasonically welded.

FIG. 4 is a schematic diagram showing an ultraviolet curable resin coating step in an example of a manufacturing method to which the present invention is applied.

FIG. 5 is a schematic diagram showing an ultraviolet irradiation step in an example of a manufacturing method to which the present invention is applied.

FIG. 6 shows another example of the manufacturing method to which the present invention is applied.
It is a schematic diagram which shows a ultraviolet curing resin application process.

FIG. 7 shows another example of the manufacturing method to which the present invention is applied.
It is a schematic diagram which shows the welding horn attachment process of a disc hub.

FIG. 8 is another example of the manufacturing method to which the present invention is applied,
It is a schematic diagram which shows an ultrasonic wave application process.

FIG. 9 shows another example of the manufacturing method to which the present invention is applied.
It is a schematic diagram which shows an ultraviolet irradiation process.

FIG. 10 is a schematic view showing a method of measuring hub breaking strength.

FIG. 11 is a characteristic diagram showing hub breaking strength of an optical disc.

FIG. 12 is a schematic view showing a conventional disc hub mounting method.

[Explanation of symbols]

 2 ... Transparent substrate 3 ... Welding horn 5 ... Disk hub 11 ... UV curable resin

Claims (1)

[Claims] 1. A method for manufacturing an optical disk, wherein both attachment by ultrasonic waves and adhesion by an ultraviolet curable resin are carried out when a hub is attached to the central portion of a transparent substrate on which a signal recording layer is formed.