JPH0468127B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a disc-shaped recording medium made of a synthetic resin material such as a video disk or an audio disk in which recorded information can be read optically. The present invention relates to a method for releasing a disk-shaped recording medium formed from a synthetic resin material from a mold after injection molding in a mold.

BACKGROUND TECHNOLOGY AND PROBLEMS As is well known, the track pitch of a video disk is extremely small, around 1 micron, and if there is distortion or the like in recorded information (signal) on a recording track, tracking errors are likely to occur during playback. Therefore, when it comes to injection molding of video discs, a high-precision molding method that does not cause distortion in the recorded information transferred by the stamper (master disc) of the mold is required. When releasing the molded video disc from the mold after molding,
There was a defect that easily caused distortion etc. in the recorded information.

That is, to explain the conventional method of molding and releasing a video disc with reference to FIGS. 1 to 3, first, as shown in FIG. and the outer periphery are pressed and fixed by an inner stamper holder 3 and an outer periphery stamper holder 4. And the above mold 1
is pressed into a fixed mold 5, molten synthetic resin 6 is injected from a sprue 7 into a cavity 8, and a video disk 9 is molded. That is, the recorded information (signal) engraved on the stamper 2 is transferred to one side of the molded video disc 9.
The inner circumferential stamper presser foot 3 has a cylindrical shape, and a punch 10 and a cylindrical ejecting pin 1 are installed inside it.
1 are inserted into each other and are slidably arranged. When the punch 10 and ejector pin 11 are pulled into the inner stamper holder 3 as shown in FIG. It is composed of

Next, after the above-mentioned molding of the video disk 9, while the video disk 9 is still soft, the punch 10 is extruded from within the extrusion pin 11 in the direction of arrow a, as shown in FIG. is pushed back by the punch 10, and the video disk 9
A center hole 13 is formed at the center.

Next, while Video Disc 9 was still soft,
Following the punching, the punch 10 is pulled back into the push-out pin 11 as shown in FIG. 3, and the mold 1 is separated from the mold 5 in the direction of arrow b and opened. And almost at the same time, push pin 1
1 is pushed out from inside the inner stamper holder 3 in the direction of arrow c, and the tip 11a of the push-out pin 11 pushes out the peripheral edge of the center hole 13 of the video disk 9 in the direction of arrow c, thereby pushing the video disk 9 into the stamper 2. Peel it off as shown by the solid line in Figure 3.

However, at this time, an air blowing passage 14 is formed between the outer circumferential surface of the ejecting pin 11 and the inner circumferential surface of the inner stamper presser foot 3, and air at a predetermined pressure is supplied to this air blowing passage 14. There is. When the ejecting pin 11 is pulled into the inner stamper holder 3 as shown in FIGS. They are brought into close contact, and the tip of the air blowing passage 14 is closed. As shown in FIG.
3 in the direction of arrow c, and the tip 11a of the extrusion pin 11 is pressed against the inner circumferential stamper presser 3.
When the air blowing passage 14 is projected outward, the tip 14a of the air blowing passage 14 is opened, and a large amount of air at a predetermined pressure is blown out from the tip 14a in the direction of the arrow d. It is configured to be sprayed into the gap between the

In summary, the conventional method for releasing the video disc 9 is to release the molds 1 and 5 after molding the video disc 9.
is separated, and the peripheral edge of the center hole 13 of the video disk 9 is mechanically pushed out using the push-out pin 11, and the video disk 9 is transferred from the stamper 2 to the third stamper.
The video disk 9 is forcibly peeled off as shown by the solid line in the figure, and then a large amount of air is blown into the gap between the peeled video disk 9 and the stamper 2, and the air prevents the video disk 9 from peeling off from the stamper 2. This was a method in which the video disk 9 was finally released from the stamper 2 as shown by the phantom line in FIG.

However, in such a conventional video disc mold release method, when the video disc 9 is forcibly peeled off from the stamper 2 by the push-out pin 11, as shown by the solid line in FIG. Distortion and the like were likely to occur in the unevenness representing the recorded information. In particular, since the video disk 9 is released from the center, the unevenness transferred from the stamper 2 tends to be more distorted toward the outer periphery of the video disk 9, resulting in warping of the video disk 9 after release. Occasionally, this occurred. Furthermore, since the video disc 9 is forcibly peeled off from the stamper 2 by the push-out pin 11,
A situation has arisen in which the unevenness of the stamper 2 is not accurately transferred to the video disk 9. It should be noted that the higher the injection pressure of the molten synthetic resin 6 into the cavity 8, the higher the transfer accuracy of the recorded information by the stamper 2, but on the other hand, the biting force of the video disk 9 against the stamper 2 increases, Since it becomes increasingly difficult to peel off the video disk 9 from the stamper 2, in such a conventional method, it is difficult to increase the injection pressure above a certain level, and the transfer accuracy of recorded information is also low. In addition, the outer circumferential surface of the tip 11a of the ejecting pin 11 is constantly sliding on the inner circumferential surface of the inner circumferential stamper presser foot 3, and if the sliding portion is worn and scrapes or rust are generated, the Defects such as shavings and rust particles were easily blown away by the air and attached to the recorded information portion of the video disk 9, causing dropouts during playback.

OBJECTS OF THE INVENTION The present invention seeks to provide a method for releasing a disc-shaped recording medium formed from a synthetic resin material, which can correct the defects as described above.

Summary of the Invention The present invention is a method for releasing a disc-shaped recording medium 9 formed from a synthetic resin material, such as a video disc, from a mold 1 to which a stamper 2 is attached after molding. After separation, air is blown onto at least the outer circumferential portion 24 side of the disk-shaped recording medium 9 to thermally shrink the surface 25 of the disk-shaped recording medium 9 on the side opposite to the stamper 2, and the resulting outer circumferential portion 24 is A first step of releasing the outer circumferential portion 24 side from the mold 1 to which the stamper 2 is attached by blowing air into the gap 26 between the stamper 2 and the stamper 2, and completion of the first step. A method for releasing a disk-shaped recording medium, comprising a second step of subsequently releasing the central portion 27 side of the disk-shaped recording medium 9 from the mold 1 to which the stamper 2 is attached, the method comprising: It is possible to obtain a shaped recording medium that is extremely easy to release from the mold and that can improve the accuracy of information transfer by a stamper.

Embodiment An embodiment in which the present invention is applied to injection molding of video discs will be described below with reference to FIGS. 4 to 9B. Note that the same structural parts as those of the conventional example shown in FIGS. 1 to 3 are given the same reference numerals, and their explanations are omitted.

First, in the present invention, as shown in FIGS. 4, 5, and 9A, an air blowing passage 21 is formed in the cylindrical outer stamper holder 4, and an annular edge 22 of the outer periphery stamper holder 4 is formed. A plurality of air outlets 2, for example, four air outlets 2, are provided on the inner circumferential surface 22a of the
3, these air blowing ports 23 are connected to the air blowing passage 21, and air at a predetermined pressure is blown from these air blowing ports 23 onto at least the outer peripheral portion 24 side of the video disc 9 formed as described above. It is configured as follows.

Next, a method for molding and releasing the video disc 9 according to the present invention will be explained in order.

First, FIG. 5 shows the injection molding process for the video disc 9, which is the same as the conventional example shown in FIG.

Next, FIG. 6 shows the punching process of the center hole 13 of the molded video disk 9, which is the same as the conventional example shown in FIG.

Next, FIGS. 7 and 8 show a process of releasing the video disk 9 from the stamper 2, which is performed subsequent to the punching process described above, and this process of releasing the video disc 9 is similar to the conventional example shown in FIG. This is done after the video disc 9 has been molded, while the video disc 9 is still soft.

That is, as shown in FIG. 7, at the same time as the mold 1 is separated and opened from the mold 5 in the direction of arrow b after the punching process, at least one of the video discs 9 is released from the plurality of air blowing ports 23. A large amount of air at a predetermined pressure is blown toward the outer peripheral portion 24 from the direction of arrow e. Then, the outer circumference 24 side of the video disk 9 is naturally and effortlessly peeled off from the stamper 2 as shown by the imaginary line.

At this time, first, as shown in FIG. 9A, when a large amount of air is blown onto the outer peripheral part 24 of the video disk 9, the surface 25 side of the outer peripheral part 24 opposite to the stamper 2 cools down, and the surface 25 side becomes heated. Shrunken. As a result, the outer peripheral part 24 is bent back from the stamper 2 in the direction of arrow f as shown in the figure, and a small gap 26 is created between the outer peripheral part 24 and the stamper 2.

Then, as shown in FIG. 9B, a large amount of air at a predetermined pressure is blown into the gap 26, and the pressure of the air pushes the video disk 9 upward in the direction of arrow f from the outer circumference 24 side to the center hole 13 side. Then, the video disk 9 is naturally peeled off from the stamper 2 without any force.

Note that this air blowing is performed for a certain period of time by setting a timer or the like. Moreover, the air to be blown does not need to be particularly cooled, and air at room temperature is sufficient. Further, the air blowing direction (direction of arrow e) from the air blowing port 23 is, for example, the direction of the stamper 2.
9A and 9.
As shown in Figure B, the direction of spraying may be at a slightly acute angle with respect to the stamper 2.

However, in the present invention, as described above, air is first blown to the outer circumference 24 side of the video disk 9, and the surface of the video disk 9 opposite to the stamper 2 is
5 is heat-shrinked, and by blowing air into the resulting gap 26, the video disk 9, especially the outer circumference 24 side, is peeled off from the stamper 2.
After the entire video disk 9 is in a state where it can be easily peeled off from the stamper 2, the push-out pin 11 is pushed out in the direction of arrow c as shown in FIG.
The central portion (periphery of the center hole 13) 27 side of the video disc 9 is pushed out by the arrow a. Therefore, the video disk 9 can be pushed out very lightly by the push-out pin 11, and the video disk 9 can be released from the stamper 2 easily and easily.

And since the video disc 9 can be easily and easily released from the stamper 2,
During the mold release operation, no distortion or the like occurs in the recorded information transferred by the stamper 2.

Furthermore, since the video disc 9 can be released from the mold very easily, the molten synthetic resin 6 can be easily released into the cavity 8.
It has become possible to improve the transfer accuracy of recorded information by the stamper 2 by combining the injection pressures of .

In addition, since the extrusion pin 11 can extrude and release the video disk 9 very easily, the eighth
As shown in the figure, there is no need to intentionally blow air between the ejector pin 11 and the inner stamper presser 3 and between the video disk 9 and the stamper 2 as in the conventional case. If this air is not blown, the push-out pin 11
There is no occurrence of defective products such as shavings, rust, etc. generated at the sliding part between the stamper and the inner circumferential stamper presser foot 3, which are blown away by the air and attached to the recorded information part of the video disk 9. .

Although the embodiments of the present invention have been described above, various modifications can be made based on the technical idea of the present invention.

For example, in the present invention, air may be blown not only onto the outer peripheral portion 24 of the video disc 9 but also over the entire surface 25 of the video disc 9.

Further, in the embodiment, air is blown from a plurality of air outlets 23 provided on the outer stamper holder 4, but any member other than the outer periphery stamper holder 4, such as the outer periphery of the mold 1 or the video disk 9 (not shown), It may be configured such that air is blown from an air nozzle attached to a member such as a take-out device.

Further, in the embodiment, after the outer circumferential portion 24 side of the video disk 9 is lifted from the mold by blowing air, the central portion side of the video disk 9 is released from the mold by the ejecting pin 11. The means for releasing the center portion of the video disk 9 from the mold is not limited to the push-out pin, and for example, a suction cup or various other means may be used.

Application Example The present invention is not limited to a mold release method for video discs and audio discs, but can be applied to a mold release method for disc-shaped recording media formed from various synthetic resin materials.

Effects of the Invention Before releasing the central part of the disc-shaped recording medium from the mold, the surface of the outer peripheral part opposite to the stamper is heat-shrinked in advance, and the resulting gap between the outer peripheral part and the stamper is Since air is blown between the two, the disc-shaped recording medium can be released from the mold easily and easily.

In addition, when releasing the central part of the disc-shaped recording medium, since the outer peripheral part has already been released from the mold, the distortion of the unevenness transferred from the stamper is greater toward the outer peripheral part of the disc-shaped recording medium. It does not become large, and warpage does not occur in the disk-shaped recording medium.

Furthermore, since the central portion of the disc-shaped recording medium is not forcibly peeled off from the stamper, the unevenness of the stamper is accurately transferred to the disc-shaped recording medium, and no defective products are produced.

Furthermore, since it becomes extremely easy to release the disc-shaped recording medium from the mold, the injection pressure of the molten synthetic resin can be increased, so that the accuracy of transferring recorded information by the stamper can be improved.

Furthermore, unlike in the past, shavings and rust particles caused by wear on the sliding parts are not blown away onto the disk-shaped recording medium by air, so there is no possibility of defective products due to adhesion of these shavings, etc. .

[Brief explanation of drawings]

1 to 3 are cross-sectional views illustrating a conventional method for molding and releasing a video disc. 4 to 9B show an embodiment of the present invention, in which FIG. 4 is an exploded perspective view, and FIGS. 5 to 8 are cross-sectional views illustrating a method for molding and releasing a video disc. 9A and 9B are enlarged sectional views of essential parts for explaining the release operation of the outer circumferential portion of the video disk by blowing air. In addition, in the symbols used in the drawings, 1...Movable mold, 2...Stamper, 4...Outer stamper holder, 5...Fixed mold, 6... Molten synthetic resin, 7... Sprue, 8 ... Cavity, 9...
Video disc, 10... Punch, 11... Push-out pin, 13... Center hole, 21... Air blowing passage, 23... Air blowing port, 24... Outer periphery of video disk, 27... Center of video disk (periphery of the center hole).

Claims (1)

[Scope of Claims] 1. A method for releasing a disc-shaped recording medium formed from a synthetic resin material from a mold to which a stamper is attached after molding the disc-shaped recording medium, the method comprising: removing at least one of the disc-shaped recording media after the mold is separated; Air is blown to the outer peripheral side to thermally shrink the surface of the disc-shaped recording medium opposite to the stamper, and the air is blown into the resulting space between the outer peripheral side and the stamper. A first step of releasing the outer peripheral side from the mold to which the stamper is attached; and after the first step, separating the center side of the disc-shaped recording medium from the mold to which the stamper is attached. A method for releasing a disk-shaped recording medium, comprising a second step of molding.