JPH09231614A - Optical disk, die for forming optical disk substrate, and method and device for forming optical disk substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deformation to an information face side where a recording layer is formed. SOLUTION: An optical disk 1 is formed with a recording layer 5, reflection layer, protection layer, hard coat film, etc., on the information face 3 side of a substrate 2; on account of these layers, a residual stress is generated deforming the optical disk 1 to the information face 3 side. On the outer peripheral end, outside the recording area on the mirror face 4 side of the substrate 2, a rib 6 is formed, serving as a 'girder' for the optical disk 1, resisting against the stress by each layer on the information face 3 side, and thereby suppressing the deformation of the optical disk 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk, an optical disk substrate molding die, an optical disk substrate molding method, and an optical disk substrate molding apparatus, and more particularly, a read-only type, a rewritable type and a write-once type used for a single plate. , An optical disk substrate molding die, an optical disk substrate molding method, and an optical disk substrate molding apparatus.

[0002]

2. Description of the Related Art Recently, information is reproduced optically,
As an optical information recording carrier that optically reproduces and records information, for example, a CD (Compact Disc: Compact Disc)
c), CD-ROM (Compact Disc Read Only Memory)
) And a rewritable type such as a magneto-optical disc, a write-once type, or various read-only optical discs are used.

In such an optical disk, as shown in FIG. 9, a laser beam 63 is incident from the mirror surface 61 side of the optical disk 60 through a substrate 62 to read information (pit row) 65 recorded on an information surface 64, Alternatively, the information (pit string) 65 is written / erased.

On the information surface 64 of the optical disc 1, a recording layer 66 in which information (pit row) 65 is written by the laser light 63 incident from the mirror surface 61 side, and a reflection for reflecting the incident laser light. The layer 67 and the protective layer for protecting these layers are the substrate 6 of the optical disc 1.
Films are sequentially formed on the surface 2 by sputtering or spin coating.

[0005]

However, in such an optical disc, each layer such as the recording layer, the reflection layer, and the protective layer formed on the information surface has a film forming method such as sputtering or spin coating. Regardless, the stress that tries to shrink remains in the directions indicated by the arrows in FIG. With respect to such a stress, conventionally, there is an optical disc that prevents distortion of the optical disc due to the stress by pasting two substrates (discs) together, and an optical disc of a type in which two discs are pasted together is Since each disc has the effect of reinforcing the strength of each other or canceling the influence of the stress generated in each disc, the problem of use due to the distortion of the optical disc due to the residual stress is solved.

However, in a so-called single-plate type optical disc in which each layer is formed on a single substrate and used, there is no conventional optical disc having a structure corresponding to the above residual stress. If deformation (deformation) occurs and this distortion (deformation) becomes large, there is a problem that the focus servo at the time of driving the optical disk does not work well.

Further, in the case of a single plate type optical disc,
It is customary to form a hard coat film using a UV curable resin or the like on the protective layer, and perform label printing on the hard coat film, but these hard coats and printing are performed simultaneously with the hard coat layer and printing. The stress that the generated ink contracts acts in the same direction as the above-mentioned stress that remains on the information surface of the optical disk, and this stress increases the distortion (deformation) that occurs in the optical disk. Is likely to occur.

However, the above-mentioned problem is caused by a phenomenon accompanying the formation of the indispensable constituent layers (recording layer, reflection layer and protective layer) on the information side of the optical disc. Therefore, when the optical disc is used as a single plate, it is necessary to deal with this point.

In view of the above, according to the first aspect of the present invention, by forming a rib portion projecting toward the mirror surface side at the mirror surface side outer peripheral end, the information surface is formed by a recording layer or a hard coat film formed on the information surface side. An object of the present invention is to provide an optical disc capable of suppressing deformation of the substrate toward the information surface side against the stress generated on the side.

According to the second aspect of the present invention, the rib portion is formed by the member constituting the substrate during the molding of the substrate, so that the stress generated on the information surface side by the recording layer or the hard coat film formed on the information surface side. It is an object of the present invention to provide an inexpensive optical disc that can prevent the substrate from being deformed toward the information surface side in opposition to the above.

An object of the present invention is to provide an optical disc in which the rib portion is formed of a hard coat film, and the deformation toward the information surface side can be further suppressed easily. There is.

According to a fourth aspect of the present invention, an annular groove is formed at the outer peripheral end of the substrate on the mirror surface side, and an annular protrusion is formed on the outer peripheral side of the annular groove to block the hard coat film liquid applied to the mirror surface side of the substrate. By forming a rib by stopping it, it is easier and
It is an object of the present invention to provide an optical disc capable of suppressing the deformation on the information surface side.

According to the fifth aspect of the present invention, the hard coat film forming the rib portion is formed on the entire mirror side of the substrate, and the hard coat film is formed so that the hard coat film becomes thinner toward the outer peripheral side of the substrate. An object of the present invention is to provide an optical disc capable of making the distortion due to the formation of a coat film uniform on the inner and outer peripheries of the substrate and suppressing the deformation toward the mirror surface side and appropriately suppressing the deformation toward the information surface side. .

According to a sixth aspect of the present invention, an optical disk substrate molding die is provided with a cooling circuit for independently cooling the outer peripheral end portion of the cavity forming the rib portion or the annular groove and the annular protrusion portion on the outer peripheral portion of the substrate on the mirror surface side. It is an object of the present invention to provide an optical disk substrate molding die capable of uniformly cooling the inner and outer peripheries of the resin forming the substrate by suppressing the distortion and deformation of the substrate.

According to a seventh aspect of the invention, when the substrate is taken out from the cavity forming the rib portion or the annular groove and the annular protrusion portion on the outer peripheral portion of the substrate on the mirror surface side, the outer peripheral portion of the substrate is projected by the outer peripheral portion ejecting mechanism. Accordingly, it is an object of the present invention to provide a method for molding an optical disk substrate, which can apply the uniform load to the substrate and take it out without deforming the substrate.

According to an eighth aspect of the present invention, there is provided an outer peripheral portion ejecting mechanism for protruding the outer peripheral portion of the substrate when the substrate is taken out from the cavity forming the rib portion or the annular groove and the annular protruding portion on the outer peripheral portion of the substrate on the mirror surface side. It is an object of the present invention to provide an optical disk substrate molding apparatus that can provide a substrate with a uniform load so that the substrate can be taken out without being deformed.

According to a ninth aspect of the present invention, a substrate is formed by molding the optical disk substrate molding die by opening the die at the outer peripheral end portion forming the rib portion or the annular groove and the annular projection portion of the cavity. By forming a draft taper that is inclined in the removal direction of the substrate when the substrate is released and taken out, the substrate can be taken out properly and easily from the mold, and the optical disc does not deform. It is intended to provide a mold for molding a substrate.

[0018]

An optical disk according to a first aspect of the present invention has at least a recording layer, a reflective layer and a protective layer formed on the information surface side of one substrate of an optical disk used as a single plate. In the optical disc on which the laser beam is incident from the mirror surface side, the above-mentioned object is achieved by having a rib portion formed on a mirror surface side outer peripheral end portion of the substrate by a predetermined member and protruding to the mirror surface side with a predetermined width by a predetermined amount. doing.

Here, the optical disc is formed by one substrate, and by forming a recording layer, a reflection layer, a protective layer, and the like on the information surface side of the substrate, the optical disk is deformed toward the information surface side. The stress remains.

The rib portion is formed on the outer peripheral end portion of the substrate outside the recording area on the mirror surface side, and is formed by a predetermined member protruding to the mirror surface side with a predetermined width by a predetermined amount.

According to the above construction, the rib portion is formed with respect to the residual stress generated by the recording layer or the like formed on the information surface side.
The function as a so-called beam can be exhibited, and the deformation of the optical disc substrate toward the information surface due to the residual stress can be suppressed.

In this case, for example, as described in claim 2, the rib portion may be formed of a member constituting the substrate.

According to the above structure, the rib portion can be formed simultaneously with the molding of the substrate, the rib portion can be easily formed, and the rib portion is generated by the recording layer or the like formed on the information surface side of the substrate. The rib portion can suppress deformation of the optical disc toward the information surface side due to residual stress.

Further, for example, as described in claim 3, the rib portion may be formed of a predetermined hard coat film.

Here, the hard coat film is formed of a UV curable resin or the like, and its strength is stronger than that of a resin which is usually used for forming a substrate.

According to the above structure, the rib portion is formed of the hard code film stronger than the strength of the substrate. Therefore, the rib portion can be easily formed, and the recording layer and the like formed on the information surface side of the substrate. The rib portion can more appropriately suppress the deformation of the optical disc toward the information surface side due to the residual stress generated by the rib portion.

Further, for example, as described in claim 4, the substrate is molded by an injection molding method or an injection compression molding method, and an annular groove and an outer periphery of the annular groove are formed at an outer peripheral end portion on the mirror surface side. An annular protrusion that is located on the side and protrudes by a predetermined amount toward the mirror surface side, and the hard coat film is
The rib portion is formed on the entire surface on the mirror surface side,
The hard coat film liquid for forming the hard coat film may be formed by being blocked by the annular groove portion and the annular protrusion portion.

According to the above structure, the rib portion can be formed more easily by the hard coat film, and the optical disc which can suppress the deformation toward the information surface side can be easily formed.

Further, for example, as described in claim 5, the hard coat film has a film thickness distribution in which the film thickness is reduced toward the outer peripheral side of the substrate except for the rib portion. Good.

According to the above structure, the distortion due to the hard coat film formed on the mirror surface side of the substrate can be made uniform over the inner and outer circumferences of the substrate, and the deformation toward the mirror surface side due to the hard coat film formed on the mirror surface side can be prevented. While suppressing, the deformation to the information surface side can be suppressed more appropriately by the hard coat film formed on the mirror surface side and the rib portion formed by this hard coat film.

According to a sixth aspect of the present invention, there is provided a mold for molding an optical disk substrate, wherein a cavity is formed at an outer peripheral end portion of the substrate on the mirror surface side, a rib portion protruding toward the mirror surface side by a predetermined amount by a predetermined width, or the substrate. An optical disk substrate molding die having an annular groove at the outer peripheral end on the mirror surface side and a cavity forming an annular protrusion located on the outer peripheral side of the annular groove and protruding a predetermined amount toward the mirror surface side. The above object is achieved by having a cooling circuit for independently cooling the outer peripheral end portion forming the rib portion or the annular groove and the annular projection portion of the cavity.

Here, the rib portion or the cavity portion for forming the annular groove and the annular protrusion portion in the substrate is filled with a larger amount of resin for molding the substrate than the other cavity portions. There is a risk that the cavity parts such as the parts will not be uniformly cooled and the other cavity parts will be deformed to the mirror surface side when the substrate is molded, but the cavity parts such as the rib parts are cooled independently by the cooling circuit. By doing so, the entire cavity can be cooled uniformly.

According to the above structure, since the cavity portion for forming the rib portion or the annular groove and the annular protrusion portion on the substrate is independently cooled, the entire cavity can be cooled uniformly, and the strain generated on the substrate. Can be further suppressed.

According to a seventh aspect of the present invention, there is provided a method for forming an optical disk substrate, wherein a cavity is formed at an outer peripheral end of the substrate on the mirror surface side, and a rib portion protruding by a predetermined width toward the mirror surface is formed, or a mirror surface of the substrate. An optical disk substrate molding method for molding an optical disk substrate by a mold having an annular groove at the outer peripheral end on the side of the annular groove and a cavity formed on the outer peripheral side of the annular groove and protruding a predetermined amount toward the mirror surface side. There
After filling and cooling a resin for molding the substrate in the cavity, when the mold is opened and the molded substrate is released and taken out, the inside of the molded substrate is removed by an internal eject mechanism. The above-mentioned object is achieved by protruding the peripheral portion and the outer peripheral ejecting mechanism at the predetermined timing with respect to the operation of the internal ejecting mechanism so as to protrude the rib portion or the annular protruding portion of the outer peripheral end portion of the molded substrate. ing.

Here, in molding an optical disk substrate, when the mold is opened and the molded substrate is projected, the inner peripheral portion of the molded substrate in the cavity is usually projected by the internal eject mechanism, but the outer peripheral end of the cavity is projected. If the part has a cavity part that forms a rib part or an annular groove and an annular protrusion part on the substrate, the mold release is not performed uniformly over the entire substrate and the substrate is deformed due to uneven load. May occur.

Therefore, if the cavity portion for forming the rib portion or the like is projected by the outer peripheral portion ejecting mechanism, the load applied to the substrate can be made uniform and the substrate can be prevented from being deformed. it can.

According to the above construction, the optical disk capable of appropriately suppressing the deformation of the recording layer or the like formed on the information surface to the information surface side due to the residual stress is suitable without the substrate being deformed during molding. Can be molded into.

According to the eighth aspect of the present invention, there is provided a method for forming an optical disk substrate, wherein a cavity is formed on the outer peripheral edge of the substrate on the mirror surface side, and a rib portion is formed so as to project to the mirror surface side by a predetermined width by a predetermined amount, or the mirror surface of the substrate. An optical disk substrate molding method for molding a substrate with a die having an annular groove at the outer peripheral end on the side of the annular groove and a cavity that is positioned on the outer peripheral side of the annular groove and forms an annular protrusion protruding a predetermined amount toward the mirror surface side. Then, after filling and cooling a resin for molding the substrate into the cavity, the mold is opened and the molded substrate is molded at the inner peripheral portion of the cavity when the molded substrate is released and taken out. An internal eject mechanism for ejecting the substrate, and an outer peripheral edge protrusion for ejecting the rib portion or the annular protrusion portion of the outer peripheral end portion of the molded substrate at a predetermined timing with respect to the operation of the internal eject mechanism. By providing a transfected mechanism, a,
The above objective has been achieved.

According to the above construction, the optical disk capable of appropriately suppressing the deformation of the recording layer or the like formed on the information surface side to the information surface side due to the residual stress is suitable without the substrate being deformed during molding. Can be molded into.

According to a ninth aspect of the present invention, there is provided a mold for molding an optical disk substrate, wherein a cavity is formed at an outer peripheral end of the substrate on the mirror surface side, and a rib portion protruding by a predetermined width toward the mirror surface is formed, or the substrate. An optical disk substrate molding die having an annular groove at the outer peripheral end on the mirror surface side and a cavity forming an annular protrusion located on the outer peripheral side of the annular groove and protruding a predetermined amount toward the mirror surface side. A direction in which the metal mold is opened at a portion of the outer peripheral end of the cavity where the rib portion or the annular groove and the annular protrusion portion are formed, and the molded substrate is released and taken out in a direction in which the substrate comes out. The above object is achieved by forming a draft taper inclined at a predetermined angle.

Here, the draft taper is formed at least at the outer peripheral end of the cavity, where ribs or annular projections are formed on the substrate, and the mold is opened to release the molded substrate. It is formed so as to be inclined at a predetermined angle in the direction in which it spreads out with respect to the direction in which the substrate is taken out.

According to the above construction, since the cavity portion forming the rib portion or the annular projection portion on the substrate is formed with the draft taper which spreads in the direction of the molded substrate coming out, the substrate is more appropriately removed from the mold. In addition, an optical disk that can be easily extracted and can appropriately suppress the deformation to the information surface side due to the residual stress of the recording layer formed on the information surface side is It can be appropriately molded without deformation.

[0043]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

1 and 2 are views showing a first embodiment of an optical disc of the present invention. FIG. 1 is a front sectional view of a half surface of the optical disc, and FIG. 2 is an outer peripheral end of the optical disc of FIG. It is an enlarged view of a part. In the present embodiment, the rib portion is formed by the same member as the substrate at the same time when the substrate of the optical disc is molded, and corresponds to claims 1 and 2.

In FIG. 1, the optical disc 1 has a substrate 2 formed by injection molding or injection compression molding using a predetermined resin (usually polycarbonate). It has a surface 3 and a mirror surface 4. A recording layer 5 is formed in a ring shape on the information surface 3 side of the substrate 2, and a reflecting layer and a protective layer (not shown) are formed on the recording layer 5. Also, the optical disc 1
If necessary, a hard coat film is formed on the protective layer or label printing is performed.

As shown in FIG. 2, the substrate 2 is provided with a rib portion 6 on the mirror surface 4 side of the outer peripheral end portion outside the recording area of the optical disc 1.
The rib portion 6 is formed at the same time when the substrate 2 is molded when the substrate 2 is molded. The rib portion 6 is formed in the shape of a band that extends over the entire circumference of the substrate 2 by a predetermined width toward the mirror surface 4 side and is closed. Further, the rib portion 6 is
The width and height are formed within the range of the standard of the optical disc, and the reading, writing and erasing of the optical disc 1 will not be hindered.

Next, the operation will be described. The optical disc 1
Has a recording layer 5, a reflection layer (not shown), a protective layer, a hard coat film, and the like formed on the information surface 3 side, and label printing is performed. Residual stress is generated and the optical disc 1 tries to be deformed.

However, since the rib portion 6 is formed on the optical disc 1 at the outer peripheral edge portion outside the recording area on the mirror surface 4 side of the substrate 2, the rib portion 6 forms a so-called "beam" with respect to the optical disc 1. It plays a role and can resist the stress due to each layer such as the recording layer 5 and suppress the deformation of the optical disc 1. Further, since the rib portion 6 is provided at the outer peripheral end portion outside the recording area of the optical disc 1, and the size of the rib portion 6 is also formed within the range of the optical disc standard, it is possible to read / write information. It does not hinder erasing.

As described above, according to the present embodiment, the rib portion 6 formed on the mirror surface 4 side acts as a so-called beam with respect to the residual stress generated by the recording layer 5 and the like formed on the information surface 3 side. The optical disk 1 that exerts the function of
Can be suppressed from being deformed toward the information surface 3 side.

FIGS. 3 and 4 are views showing a second embodiment of the optical disk of the present invention. In this embodiment, the rib portion is formed of a hard coat film. It corresponds to item 3. 3 is a front sectional view of a half surface of the optical disc, and FIG. 4 is an enlarged view of an outer peripheral end portion of the optical disc of FIG.

In FIG. 3, an optical disk 10 has a substrate 11 formed by injection molding or injection compression molding using a predetermined resin, and the substrate 11 is an information surface 12.
And a mirror surface 13. On the information surface 12 side of the substrate 11, a recording layer 14 is formed in a ring shape, and the recording layer 1
Although not shown, a reflective layer and a protective layer are formed on the surface 4. Further, the optical disc 10 has a hard coat film formed on the protective layer or label printing as necessary.

The substrate 11 has a hard coat film 15 of a predetermined thickness formed by coating a UV curable resin or the like on the mirror surface 13 side by a spin coating method, and the outer peripheral end portion outside the recording area of the optical disk 10. As shown in FIG. 4, the rib portion 16 is formed of the hard coat film 15. That is, the rib portion 16 is the hard coat film 1
5 is formed by spin coating, the temperature distribution of the substrate 11 is controlled, and an extra hard coat film liquid is added to the substrate 11.
By adjusting the number of rotations of the substrate 11 when it is shaken in the outer peripheral direction by the rotation of, the hard coat film liquid is raised to the outer peripheral end portion outside the recording area of the optical disc 10 to form the hard coat film 15. It is formed at the same time, and is formed in a closed strip shape that projects toward the mirror surface 13 side by a predetermined amount with a predetermined width over the entire circumference of the substrate 11. The hard coat film 15 is stronger than the material of the substrate 11 (usually polycarbonate is used). In addition, the rib portion 16 is formed such that its width and height are within the range of the standard of the optical disc, so that the reading of the optical disc 10
There is no problem in writing and erasing.

Next, the operation will be described. The optical disk 10
Has a recording layer 14, a reflection layer (not shown), a protective layer, and a hard coat film, which are formed on the information surface 12 side, and label printing is performed. Therefore, each of these layers remains in the direction indicated by the arrow in FIG. A stress is generated, and the optical disc 10 tries to be deformed.

However, the optical disc 10 has a substrate 11
A hard coat film 15 having a stronger strength than the substrate 11 is formed on the mirror surface 13 side of the hard coat film 1
Since the rib portion 16 is formed on the outer peripheral end portion of the optical disc 10 outside the recording area of the optical disc 10, the hard coat film 15 and the rib portion 16 can counter the stress caused by each layer such as the recording layer 5 of the optical disc 10. Therefore, the deformation of the optical disc 1 can be further suppressed.

As described above, according to this embodiment, the mirror surface 13 side is stronger than the substrate 11 against the residual stress generated by the recording layer 14 and the like formed on the information surface 12 side of the substrate 11. Since the hard coat film 15 is formed and the rib portion 16 is formed by the hard coat film 15 on the outer peripheral end of the optical disc 10 on the mirror surface 13 side, deformation of the optical disc 10 toward the information surface 12 side due to residual stress is further suppressed. It can be suppressed more appropriately.

FIGS. 5 and 6 are views showing a third embodiment of the optical disc of the present invention. In this embodiment, an annular groove portion and an annular protrusion portion are formed on the outer peripheral end portion of the substrate, and A rib portion is formed by the hard coat film blocked by the annular groove portion and the annular protrusion portion, and corresponds to claims 1 and 4.

FIG. 5 is a front sectional view of a half surface of the optical disk, and FIG. 6 is an enlarged view of an outer peripheral end portion of the optical disk of FIG.

In FIG. 5, the optical disc 20 has a substrate 21 formed by injection molding or injection compression molding using a predetermined resin, and the substrate 21 has an information surface 22.
And a mirror surface 23. A recording layer 24 is formed in a ring shape on the information surface 22 side of the substrate 21.
Although not shown, a reflective layer and a protective layer are formed on the surface 4. Further, the optical disc 20 has a hard coat film formed on the protective layer or label printing as required.

As shown in FIG. 6, the substrate 21 has an annular groove portion 25, which is formed in an annular shape along the outer peripheral end portion and has a predetermined width and a predetermined depth, at the outer peripheral end portion on the mirror surface 23 side. ,
An annular protrusion 26, which is formed in an annular shape with a predetermined width and a predetermined height, is formed on the outer peripheral side of the annular groove 25. The annular groove 25 and the annular protrusion 26 are formed at the same time when the substrate 21 is formed. It is formed.

The substrate 21 has a hard coat film 27 formed on the mirror surface 23 side of the hard coat film liquid such as UV curable resin by a spin coating method to a predetermined thickness. During spin coating, the temperature distribution of the substrate 21 is controlled and the number of rotations of the substrate 21 is adjusted, and the rotation of the substrate 21 causes the mirror surface 23 of the substrate 21 to rotate.
The hard coat film liquid to be applied to the side is collected at the outer peripheral end of the substrate 21 to enter the annular groove 25 and is blocked by the annular protrusion 26 to form the rib 28. That is, as shown in FIG. 6, a rib portion 28 is formed on the outer peripheral edge of the hard coat film 27 outside the recording area of the optical disc 20.
The rib portion 28 is formed in the shape of a closed strip that projects a predetermined amount toward the mirror surface 23 side over the entire circumference of the substrate 21. The hard coat film 27 is formed on the substrate 2
Its strength is stronger than that of the No. 1 material. Further, the rib portion 28 is
The width and the height are formed within the range of the standard of the optical disc, and the reading, writing and erasing of the optical disc 20 will not be hindered.

Next, the operation will be described. The optical disk 20
Since a recording layer 24, a reflection layer, a protective layer, and a hard coat (not shown) are formed on the information surface 22 side, and label printing is performed, these layers cause residual stress in a direction indicated by an arrow in FIG. Occurs and tries to deform the optical disc 20 toward the information surface 22 side.

However, the optical disc 20 has a substrate 21
An annular groove 25 and an annular protrusion 26 are formed at the outer peripheral end of the substrate 21, and a hard coat film 27 having a stronger strength than that of the substrate 21 is formed on the mirror surface 23 side of the substrate 21 by spin coating. When the hard coat film 27 is applied, the hard coat film liquid enters the annular groove portion 25 and is blocked by the annular protrusion portion 26 so that the hard coat film 27 causes the hard coat film 27 to cover the outer peripheral end portion outside the recording area of the optical disc 20. The rib portion 28 is formed on the recording layer 2 of the optical disc 20 by the hard coat film 27 and the rib portion 28.
It is possible to counter the stress on the information surface 22 side due to each layer such as No. 4 and the like, the deformation of the optical disk 20 can be further suppressed, and the rib portion 28 is easily and appropriately formed by the hard coat film 27. be able to.

As described above, according to this embodiment, the hard coat film 27, which is stronger than the substrate 21, on the mirror surface 23 side.
Since the hard coat film 27 forms the rib portion 27 on the outer peripheral end of the optical disc 20 on the mirror surface 23 side, the optical disc due to the residual stress generated by the recording layer 24 and the like formed on the information surface 22 side. Information side 2 of 20
The deformation toward the second side can be suppressed more appropriately, and the hard coat film 27 applied by the spin coat method by the annular groove 25 and the annular protrusion 26 formed with the rib 28 at the outer peripheral end of the substrate 21. The rib portion 28 can be easily and appropriately formed because the rib portion 28 is formed so as to be closed.

FIG. 7 is a diagram showing a fourth embodiment of the optical disk of the present invention. In this embodiment, a hard coat film is formed on the mirror surface side of the substrate toward the outer peripheral side of the substrate, and A rib portion is formed on the end portion by a hard coat film, and corresponds to claims 1 and 5. The present embodiment is applied to the same optical disc as the second embodiment, and in the description of the present embodiment, the reference numerals used in FIGS. 3 and 4 are used as they are, This will be described below. Further, FIG. 7 is a front sectional view of a half surface of the optical disc.

In FIG. 7, the optical disk 30 has a substrate 11 formed by injection molding or injection compression molding using a predetermined resin, and the substrate 11 has the same information as the second embodiment. It has a surface 12 and a mirror surface 13. A recording layer 14 is formed in a ring shape on the information surface 12 side of the substrate 11, and a reflecting layer and a protective layer (not shown) are formed on the recording layer 14. Further, the optical disc 30 has a hard coat film formed on the protective layer or label printing as necessary.

The substrate 11 has a hard coat film 31 formed on the mirror surface 13 side by coating a UV curable resin or the like by a spin coat method.
In the outer peripheral end portion outside the recording area of the first optical disc 30,
The rib portion 32 is formed. Similarly to the above, the rib portion 32 is formed at the same time as the formation of the hard coat film 31 by causing the hard coat film liquid to rise to the outer peripheral end portion outside the recording area of the optical disc 30 during the formation of the hard coat film 31. The substrate 11 is formed in a closed strip shape with a predetermined width and protruding toward the mirror surface 13 side over the entire circumference of the substrate 11.

The hard coat film 31 is formed by adjusting the setting of the coating conditions when the hard coat film liquid is applied, so that the substrate 1 is removed except for the rib portion 32 as shown in FIG.
It is formed so that the film thickness thereof becomes thinner from the inner peripheral portion to the outer peripheral portion.

The width and height of the rib portion 32 are
It is formed within the standard of the optical disc, and there is no problem in reading, writing and erasing of the optical disc 30.

Next, the operation will be described. The optical disk 30
In the same manner as above, residual stress is generated on the information surface 12 side, and the optical disc 10 tries to deform toward the information surface 12 side.

However, the optical disk 30 has a substrate 11
Of the hard coat film 31 having stronger strength than the substrate 11 on the mirror surface 13 side of
Since the rib portion 32 is formed on the outer peripheral end portion outside the recording area of the optical disc 30, the hard coat film 31 and the rib portion 32 can counter the stress due to each layer such as the recording layer 5 of the optical disc 30, The deformation of the optical disc 30 can be further suppressed.

Further, when the rib portion 32 is formed by the hard coat film 31 on the outer peripheral end portion of the substrate 11 on the mirror surface 13 side, it occurs due to a structural reason that the information surface 12 and the mirror surface 13 side of the substrate 11 are asymmetric. Although a stress to deform the mirror surface 13 is generated, the hard coat film 31 causes the substrate 1 to be deformed.
Since the film thickness is formed from the inner peripheral portion of the substrate 1 toward the outer peripheral portion thereof, the strain due to the stress for deforming the mirror surface 13 side is uniform from the inner peripheral portion to the outer peripheral portion of the substrate 11. Therefore, the deformation of the substrate 11 toward the mirror surface 13 side can be suppressed.

As described above, according to the present embodiment, the hard coat film 31 stronger than the substrate 11 is formed on the mirror surface 13 side against the residual stress generated on the information surface 12 side, and the hard coat film is formed. Since the rib portion 32 is formed by the film 31 on the outer peripheral end of the optical disc 30 on the mirror surface 13 side, the deformation of the optical disc 30 toward the information surface 12 side due to residual stress can be suppressed more appropriately. Further, since the hard coat film 31 is formed such that the film thickness becomes thinner from the inner peripheral portion of the substrate 11 toward the outer peripheral portion thereof, it is caused by forming the hard coat film 31 on the mirror surface 13 side of the substrate 11. The strain caused becomes uniform from the inner peripheral portion to the outer peripheral portion of the substrate 11, and the deformation of the substrate 11 toward the mirror surface 13 side can be suppressed.

FIG. 8 is a diagram showing one embodiment of a mold for molding an optical disk substrate, an optical disk substrate molding method and an optical disk substrate molding apparatus of the present invention. 8 is a partial cross-sectional view of an optical disk substrate molding apparatus for molding the optical disk substrate of the first embodiment.

In FIG. 8, the optical disk substrate molding device 4
0 includes a fixed mold 41 and a movable mold 42, and the fixed mold 41 and the movable mold 42 include a fixed mirror surface block 43 and a movable mirror surface block 44, respectively, on opposite sides. The fixed mirror surface block 43 and the movable mirror surface block 44
Thus, a cavity 45 for molding the substrate is formed, and as will be described later, a resin 46 which is a material of the substrate, for example, polycarbonate is filled and cooled in the cavity 45 to mold the substrate.

The cavity 45 is a movable mirror surface block 44.
An annular recess 47 is formed at the outer peripheral end on the side, and the annular recess 47 is for forming an annular rib portion projecting at a predetermined width and at a predetermined height on the mirror surface side of the substrate at the outer peripheral end of the substrate. Is.

At least the inner peripheral side wall of the annular groove portion 47 extends in the direction of the fixed mold 41, that is, in the direction in which the filled and cooled substrate is removed during the mold release (downward in FIG. 8). It is formed on an inclined surface that is slightly inclined, that is, a draft taper is formed, and the draft taper improves the punching performance of the substrate at the time of mold release. It is desirable that the punched taper is also formed on the outer peripheral side wall of the cavity 45, but when it is formed on the outer peripheral side wall, it is necessary to form it within the range of the optical disc standard.

The fixed mold 41 has a fixed mirror surface block 43.
Facing each other, a plurality of fixed mirror surface cooling pipes 48 provided in an ordinary fixed mold are provided, and the fixed mirror surface cooling pipe 48 is supplied with a predetermined refrigerant therein to fix the fixed mirror surface block. The substrate resin 46 filled in the cavity 45 via 43 is cooled.

The movable mold 42 has a movable mirror surface block 44.
, A plurality of movable mirror surface cooling pipes 49 provided in a normal movable mold are provided, and the movable mirror surface cooling pipes 49 are supplied with a predetermined refrigerant therein so that the movable mirror surface block is provided. Resin 4 for substrate in cavity 45 via 44
Cool 6

Further, the movable die 42 is provided with an annular recess cooling pipe (cooling circuit) 50 in a spiral shape near the annular recess 47, and the annular recess cooling pipe 50 is provided.
Cools the substrate resin 46 filled in the annular recess 47. The annular recess cooling pipe 50 is provided in a system separate from the fixed mirror surface cooling pipe 48 and the movable mirror surface cooling pipe 49, and is independent of the fixed mirror surface cooling pipe 48 and the movable mirror surface cooling pipe 49. The substrate resin 46 filled in the annular recess 47 is cooled by the coolant.

The annular recess 47 of the movable mirror surface block 44.
A rib portion eject mechanism (outer peripheral portion eject mechanism) 51 is provided on the top portion of the rib portion eject mechanism 51. When the molded substrate is released from the molds 41 and 42, the rib portion eject mechanism 51 forms an annular recess 47. The rib portion of the filled and cold-molded substrate is projected.

Next, the operation will be described. In the optical disk substrate molding apparatus 40, the resin 46 for the substrate is provided in the cavity 45.
The cooling medium is filled with the refrigerant and is usually cooled by passing a coolant through the fixed mirror surface cooling pipe 48 and the movable mirror surface cooling pipe 49. However, in the optical disk substrate molding apparatus 40, an annular recess is formed at the outer peripheral end of the cavity 45 toward the movable mirror surface block 44 side. Since the concave portion 47 is formed, the annular concave portion 47 is filled with more resin 46 than the other portions of the cavity 45. for that reason,
The resin 46 in the annular recess 47 is cooled less easily than the resin 46 in the other portions of the cavity 45, and uneven cooling occurs.

However, the optical disk substrate molding apparatus 40 is provided with an annular recess cooling pipe 50, which is independent of the fixed mirror surface cooling pipe 48 and the movable mirror surface cooling pipe 49, near the annular recess 47. The resin 46 of 47 can be cooled by the refrigerant in the annular recess cooling pipe 50.

Therefore, the resin 46 in the cavity 45 having the annular recess 47 for forming the rib portion can be uniformly cooled, and the deformation of the substrate having the rib portion due to uneven cooling can be suppressed. it can.

When the above cooling is completed, the movable mold 42 is moved upward to release the substrate molded in the cavity 45. At this time, normally, the internal eject provided near the center of the cavity 45 is ejected. The optical disc substrate molding apparatus 40 is configured to push out the central portion of the substrate molded by the mechanism, blow air from the release air blowing mechanism provided around the internal eject mechanism, and release the substrate to take it out. Has an annular recess 47 recessed toward the movable mirror surface block 44 at the outer peripheral end of the cavity 45, and therefore, the normal internal eject mechanism and the release air blowing mechanism alone do not affect the substrate during release and removal. A uniform load is applied, which may cause deformation of the substrate.

However, in the optical disk substrate molding apparatus 40, the rib eject mechanism 51 is provided on the top of the annular recess 47.
The rib eject mechanism 51 operates at an appropriate timing with respect to the operation of the internal eject mechanism when the substrate is released, and the rib portion of the substrate filled in the annular recess 47 and cooled and formed. Stick out. As a result, the optical disk substrate having the rib portion on the outer peripheral portion can be properly released from the molds 41 and 42 without applying a non-uniform load, and the substrate can be prevented from being deformed. be able to.

Since the annular recess 47 is formed with a taper on at least the inner peripheral side wall thereof, when the substrate is released from the movable mold 42, the substrate can be easily released and taken out. Therefore, it is possible to prevent the substrate from being deformed due to a defective extraction.

In the above embodiment, the case of molding the substrate of the second embodiment of the optical disk has been described, but the same applies to the case of molding the substrate of the third embodiment. be able to.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

For example, in each of the above embodiments, the rib portion is formed in a closed strip shape, but the shape of the rib portion is not limited to the closed strip shape, and for example, a strip rib having a predetermined length is used. May be formed at predetermined intervals.

[0090]

According to the optical disk of the first aspect of the present invention, the rib portion functions as a so-called beam against the residual stress generated by the recording layer or the like formed on the information surface side, It is possible to suppress the deformation of the optical disk substrate toward the information surface side due to the residual stress.

According to the optical disc of the second aspect of the present invention, the rib portion can be formed simultaneously with the molding of the substrate,
The rib portion can be easily formed, and the deformation of the optical disc toward the information surface side due to the residual stress generated by the recording layer or the like formed on the information surface side of the substrate can be suppressed by the rib portion.

According to the optical disc of the third aspect of the present invention, since the rib portion is formed of the hard code film stronger than the strength of the substrate, the rib portion can be easily formed and the information surface side of the substrate can be formed. The rib portion can more appropriately suppress the deformation of the optical disc toward the information surface side due to the residual stress generated by the recording layer or the like formed.

According to the optical disc of the fourth aspect of the present invention, the rib portion can be more easily formed by the hard coat film, and the optical disc which can suppress the deformation toward the information surface side can be easily formed. be able to.

According to the optical disc of the fifth aspect of the present invention, the distortion due to the hard coat film formed on the mirror surface side of the substrate can be made uniform over the inner and outer peripheries of the substrate, and the hard coat film formed on the mirror surface side. While suppressing the deformation to the mirror surface side, the deformation to the information surface side can be suppressed more appropriately by the hard coat film formed on the mirror surface side and the rib portion formed by this hard coat film.

According to the die for molding an optical disk substrate of the sixth aspect of the present invention, since the cavity portion for forming the rib portion or the annular groove and the annular protrusion portion on the substrate is independently cooled, the entire cavity is made uniform. It can be cooled, and the strain generated in the substrate can be further suppressed.

According to the optical disk substrate molding method of the seventh aspect of the present invention, an optical disk capable of appropriately suppressing the deformation of the recording layer formed on the information surface to the information surface due to residual stress is molded. Sometimes the substrate can be properly molded without deformation.

According to the optical disk substrate molding apparatus of the eighth aspect of the present invention, an optical disk capable of appropriately suppressing the deformation of the recording layer formed on the information surface to the information surface due to residual stress is molded. Sometimes the substrate can be properly molded without deformation.

According to the optical disk substrate molding die of the invention described in claim 9, the cavity portion forming the rib portion or the annular protrusion portion on the substrate is formed with a draft taper which spreads in the direction of removal of the molded substrate. Therefore, the substrate can be extracted from the mold more properly and easily,
(EN) An optical disc capable of appropriately suppressing the deformation of the recording layer formed on the information surface side to the information surface side due to residual stress can be properly formed without the substrate being deformed due to ejection failure during molding. it can.

[Brief description of drawings]

FIG. 1 is a front cross-sectional view of a half surface of an optical disc to which an optical disc according to a first embodiment of the present invention is applied.

FIG. 2 is an enlarged view of an outer peripheral edge portion of the optical disc of FIG.

FIG. 3 is a front sectional view of a half surface of an optical disc to which the second embodiment of the optical disc of the present invention is applied.

FIG. 4 is an enlarged view of an outer peripheral edge portion of the optical disc of FIG.

FIG. 5 is a front sectional view of a half surface of an optical disc to which an optical disc according to a third embodiment of the present invention is applied.

FIG. 6 is an enlarged view of an outer peripheral end portion of the optical disc of FIG.

FIG. 7 is a front sectional view of a half surface of an optical disc to which an optical disc according to a fourth embodiment of the present invention is applied.

FIG. 8 is a front partial cross-sectional view of an optical disk substrate molding apparatus to which an embodiment of an optical disk substrate molding die, an optical disk substrate molding method, and an optical disk substrate molding apparatus of the present invention is applied.

FIG. 9 is an enlarged front sectional view of a conventional optical disc.

FIG. 10 is a front cross-sectional view of a half surface of an optical disc for schematically showing deformation of a conventional optical disc due to residual stress.

[Explanation of symbols]

 1, 10, 20, 30 Optical disk 2, 11, 21 Substrate 3, 12, 22 Information surface 4, 13, 23 Mirror surface 5, 14, 24 Recording layer 6, 16, 28, 32 Rib portion 15, 27, 31 Hard coat Film 25 Annular groove 26 Annular protrusion 40 Optical disk substrate molding device 41 Fixed mold 42 Movable mold 43 Fixed mirror surface block 44 Movable mirror surface block 45 Cavity 46 Resin 47 Annular recess 48 Fixed mirror surface cooling pipe 49 Movable mirror surface cooling pipe 50 Ring Piping for cooling recess 51 Rib eject mechanism

Claims (9)

[Claims] 1. An optical disc in which at least a recording layer, a reflection layer and a protective layer are formed on the information surface side of one substrate of an optical disc used as a single plate, and a laser beam is incident from the mirror side of the substrate. An optical disc having a rib portion formed on a mirror-surface-side outer peripheral end thereof by a predetermined member protruding toward the mirror-surface side with a predetermined width by a predetermined amount. 2. The optical disc according to claim 1, wherein the rib portion is formed of a member that constitutes the substrate. 3. The optical disc according to claim 1, wherein the rib portion is formed of a predetermined hard coat film. 4. The substrate is molded by an injection molding method or an injection compression molding method, and has an annular groove at the outer peripheral end on the mirror surface side and a predetermined amount on the outer peripheral side of the annular groove. A projecting annular protrusion is formed, the hard coat film is formed on the entire surface of the mirror side, and the rib portion has a hard coat film liquid for forming the hard coat film, the annular groove and the annular protrusion. 4. The optical disc according to claim 3, wherein the optical disc is formed by being blocked by. 5. The optical disk according to claim 4, wherein the hard coat film has a film thickness distribution in which the film thickness becomes thinner toward the outer peripheral side of the substrate except for the rib portion. 6. A cavity for forming a rib portion protruding toward the mirror surface side by a predetermined amount on the mirror surface side outer peripheral end portion of the substrate,
Alternatively, in an optical disk substrate molding die having an annular groove on the outer peripheral end of the substrate on the mirror surface side, and a cavity that is located on the outer peripheral side of the annular groove and forms an annular protrusion protruding toward the mirror surface by a predetermined amount. A die for molding an optical disk substrate, further comprising a cooling circuit that independently cools the outer peripheral end portion forming the rib portion or the annular groove of the cavity and the annular protrusion portion. 7. A cavity for forming a rib portion protruding toward the mirror surface side by a predetermined amount on the mirror surface side outer peripheral edge portion of the substrate,
Alternatively, an optical disk substrate is formed by a die having a cavity at the outer peripheral edge of the substrate on the mirror surface side, the cavity having an annular groove and an annular protrusion located on the outer peripheral side of the annular groove and protruding a predetermined amount toward the mirror surface. A method of molding an optical disk substrate, wherein after the resin for molding the substrate is filled in the cavity and cooled, the mold is opened and the molded substrate is released and taken out. While ejecting the inner peripheral portion of the molded substrate by an ejecting mechanism, the outer peripheral ejecting mechanism causes the rib portion or the annular protruding portion of the outer peripheral end portion of the molded substrate to be formed at a predetermined timing with respect to the operation of the internal eject mechanism. A method for molding an optical disk substrate, which is characterized in that it is projected. 8. A cavity for forming a rib portion protruding toward the mirror surface side by a predetermined amount on the mirror surface side outer peripheral end portion of the substrate,
Alternatively, the substrate is molded by a die having a cavity at the outer peripheral end of the substrate on the mirror surface side, which forms an annular groove and an annular protrusion located on the outer peripheral side of the annular groove and protruding a predetermined amount toward the mirror surface. An optical disk substrate molding apparatus, wherein after filling and cooling a resin for molding the substrate into the cavity, the mold is opened, and the molded substrate is released from the mold and taken out of the cavity. An internal eject mechanism for projecting the molded substrate at the peripheral portion, and an outer peripheral eject mechanism for projecting the rib portion or the annular projection portion at the outer peripheral end of the molded substrate at a predetermined timing with respect to the operation of the internal eject mechanism. An optical disk substrate molding apparatus comprising: 9. A cavity for forming a rib portion protruding toward the mirror surface side by a predetermined amount on the mirror surface side outer peripheral end portion of a substrate,
Alternatively, in an optical disk substrate molding die having an annular groove on the outer peripheral end of the substrate on the mirror surface side, and a cavity that is located on the outer peripheral side of the annular groove and forms an annular protrusion protruding toward the mirror surface by a predetermined amount. When the mold is opened and the molded substrate is released and taken out, the substrate is removed at the rib portion or the portion where the annular groove and the annular protrusion are formed at the outer peripheral end of the cavity. An optical disk substrate molding die, characterized in that a draft taper is formed which is inclined at a predetermined angle in a direction in which it extends in the direction.