JP3521167B2 - optical disk - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rewritable type and a write-once type.
Or optical discs used for playback only,
Recording layer and reflection on the information side of one substrate used in a single plate
Layer and protective layer are formed, and laser light is incident from the mirror side.
A single plate type optical disc.

[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 disc, as shown in FIG. 9, a laser beam 63 is incident from a mirror surface 61 side of the optical disc 1 through a substrate 62, and information (pit row) 65 recorded on an information surface 64 is read, 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. In response to such stress, conventionally, there is an optical disc which prevents the distortion of the optical disc due to the stress by bonding two substrates (discs) together. This
The optical disc of the type in which the two discs are bonded together has the effect that each disc reinforces each other's strength or cancels the influence of the stress generated in each disc.
It solves the problem of use due to the distortion of the optical disk due to residual stress.

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.

The present invention is applicable to a single plate type optical disc.
It was made in order to solve the above problems.
It is an object, with a simple configuration, the substrate is to provide an optical disk capable of suppressing the deformation on the information surface side.

[0010]

The optical disc of the present invention comprises:
In an optical disc in which at least a recording layer, a reflective layer and a protective layer are formed on the information surface side of one substrate used as a single plate, and a laser beam is incident from the mirror surface side, the outer peripheral end of the substrate on the mirror surface side. to have a rib portion formed by a predetermined projection amount in a predetermined width mirror side.

Here, the optical disk is formed by one substrate, and by forming a recording layer, a reflection layer, a protective layer, etc. 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 an outer peripheral end portion of the substrate outside the recording area on the mirror surface side, and is formed by a predetermined member protruding toward the mirror surface side with a predetermined width by a predetermined amount. According to this configuration, the rib portion functions as a so-called beam to the residual stress generated by the recording layer and the like formed on the information surface side, and the rib portion moves toward the information surface side of the optical disk substrate due to the residual stress. Can be suppressed.

Specifically, the rib portion is a predetermined hard core.
It is formed of a quartz film. Here, the hard coat film is formed of a UV curable resin or the like, and its strength is higher than that of a resin that is usually used for forming a substrate.

According to the above construction, 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 deformation of the information surface of the optical disc due to residual stress generated by more ribs, can be more appropriately suppressed.

Further, the substrate is formed by an injection molding method or
In addition to being molded by injection compression molding,
An annular groove at the peripheral end and the mirror surface located on the outer peripheral side of the annular groove.
An annular protrusion that protrudes a certain amount on the
The film is formed on the entire surface of the mirror surface, and the rib portion is formed.
Is the above-mentioned hard coat film liquid for forming the hard coat film.
Being blocked by the annular groove and the annular protrusion
Is formed. According to this structure, the rib portion can be formed more easily by the hard coat film,
It is possible to easily form an optical disc that can suppress the deformation toward the information surface side.

Further , the hard coat film includes the rib portion.
Except for the portion, the film thickness becomes thinner on the outer peripheral side of the substrate.
It may have a film thickness distribution. According to this configuration, 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, while suppressing the deformation toward the mirror surface side due to the hard coat film formed on the mirror surface side. The deformation to the information surface side is caused by the hard coat film formed on the mirror surface side and the rib portion formed by this hard coat film .
Ri, can be more appropriately suppressed.

A mold for molding an optical disk substrate used in the present invention is a cavity for forming a rib portion protruding toward the mirror surface side by a predetermined width by a predetermined amount on the outer peripheral end of the substrate on the mirror surface side, or the mirror surface side of the substrate. An optical disk substrate molding die having an annular groove at the outer peripheral end thereof and an annular protrusion located on the outer peripheral side of the annular groove and protruding a predetermined amount toward the mirror surface side. It has a cooling circuit which independently cools the outer peripheral end portion forming the rib portion or the annular groove and the annular protrusion.

Here, the cavity portion for forming the rib portion or the annular groove and the annular protrusion portion on 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 is independently cooled, it is possible to uniformly cool the entire cavity and the strain generated in the substrate. Can be further suppressed.

Further, the optical disk substrate molding method of the present invention used in the present invention is such that a cavity is formed in the outer peripheral edge of the substrate on the mirror surface side, and a rib portion protruding by a predetermined width toward the mirror surface side is formed, or the substrate is formed. Optical disk substrate molding method for molding an optical disk substrate with a mold having an annular groove at the outer peripheral end on the mirror surface side and a cavity formed on the outer peripheral side of the annular groove and projecting a predetermined amount toward the mirror surface side. To
Oite, after resin filling-cooling for molding the substrate into the cavity, when taking out the substrate having the molding opening the mold by releasing and the forming by the internal ejection mechanism The inner peripheral part of the substrate is projected, and the rib part or the annular protrusion part of the outer peripheral end part of the molded substrate is projected by the outer peripheral part eject mechanism at a predetermined timing with respect to the operation of the inner eject mechanism.
You

Here, in molding an optical disk substrate, when the mold is opened and the molded substrate is ejected, the inner peripheral portion of the molded substrate in the cavity is usually ejected by the internal eject mechanism, but the outer peripheral end of the cavity is ejected. 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 side to the information surface side due to the residual stress is suitable without deforming the substrate during molding. Can be molded into.

Further , the optical disk substrate molding used in the present invention
The device has a cavity formed with a rib portion protruding toward the mirror surface side by a predetermined amount on the mirror surface side outer peripheral edge portion, or an annular groove and the annular groove at the mirror surface side outer peripheral edge portion of the substrate. In an optical disk substrate molding apparatus that molds a substrate with a mold that has a cavity that is located on the outer peripheral side and that forms an annular protrusion that protrudes a certain amount toward the mirror surface side, a resin for molding the substrate in the cavity is used. After filling and cooling, the internal eject mechanism for ejecting the molded substrate in the cavity inner peripheral portion when the mold is opened and the molded substrate is released and taken out, and the operation of the internal eject mechanism On the other hand, an outer peripheral ejecting mechanism for protruding the rib portion or the annular protrusion portion at the outer peripheral end portion of the molded substrate at a predetermined timing is provided .

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

Further, the optical disk substrate molding die used in the present invention has 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. There is a removal of the substrate when the mold is opened and the molded substrate is released and taken out 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. A draft taper is formed which is inclined at a predetermined angle in the direction in which it extends.

Here, the draft taper is formed at least at the outer peripheral end of the cavity, where ribs or annular protrusions 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 protrusion portion on the substrate is formed with the draft taper which spreads in the direction of the molded substrate coming out, the substrate can be 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.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and therefore have various technically preferable limitations. However, the scope of the present invention refers to the present invention particularly in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

1 and 2 are views showing a first embodiment of an optical disk of the present invention. FIG. 1 is a front sectional view of a half surface of the optical disk, and FIG. 2 is an outer peripheral edge of the optical disk of FIG. It is an enlarged view of a part. In this embodiment, the rib portion is made of the same material as the substrate at the same time when the substrate of the optical disc is molded.
It was formed .

In FIG. 1, an 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 has 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 against 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. In addition,
FIG. 3 is a front cross-sectional view of the half surface of the optical disk, and FIG.
3 is an enlarged view of the outer peripheral edge portion of the optical disc of FIG.

In FIG. 3, the optical disc 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 formed in a predetermined thickness on the mirror surface 13 side by coating a UV curable resin or the like by a spin coat 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 with respect to 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 the hard coat film blocked by the annular groove and the annular projection portion is obtained by forming a rib portion.

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

In FIG. 5, an optical disk 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 formed in an annular shape along the outer peripheral end portion and having 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 of a predetermined thickness formed by coating a hard coat film liquid such as UV curable resin on the mirror surface 23 side by a spin coating method. 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 disc 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 the present 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 so that the outer peripheral side of the substrate is thinner and the hard coat layer on the end portion is obtained by forming a rib portion. 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. In addition, FIG.
It is a front cross-sectional view of the half surface of the optical disc.

In FIG. 7, the optical disc 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 condition when the hard coat film liquid is applied, so that the rib portion 32 is removed 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 the 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 an embodiment of a mold for molding an optical disk substrate, an optical disk substrate molding method and an optical disk substrate molding apparatus used in the present invention . Note that FIG.
FIG. 3 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 apparatus 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

The movable mold 42 is provided with a spiral annular cooling pipe (cooling circuit) 50 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, the optical disk substrate molding apparatus 40 has an annular recessed portion on the outer peripheral end of the cavity 45 toward the movable mirror surface block 44. 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, the internal eject provided usually near the center of the cavity 45 is removed. 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 at 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.

Further, 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.

The invention made by the present inventor has been specifically described above based on the preferred embodiments, but 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.

[0076]

The main effects of the optical disk of the present invention are as follows. (1) With respect to the residual stress generated by the recording layer or the like formed on the information surface side, the rib portion functions as a so-called beam to prevent the optical disk substrate from being deformed toward the information surface side by the residual stress. Can be suppressed.

(2) Since the rib portion is formed of a hard-coded film which is stronger than the strength of the substrate, the rib portion can be easily formed and is generated by the recording layer or the like formed on the information surface side of the substrate. The deformation of the optical disc toward the information surface side due to residual stress can be suppressed more appropriately by the rib portion.

(3) 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.

(4) 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, while suppressing the deformation toward the mirror surface side due to the hard coat film formed on 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.

[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 disc 2, 11, 21 substrate 3, 12, 22 Information side 4, 13, 23 Mirror surface 5, 14, 24 recording layers 6, 16, 28, 32 Rib 15, 27, 31 Hard coat film 25 annular groove 26 Annular protrusion 40 Optical disk substrate molding machine 41 Fixed mold 42 Movable mold 43 Fixed mirror surface block 44 Movable mirror surface block 45 cavities 46 resin 47 annular recess 48 Fixed mirror surface cooling pipe 49 Movable mirror surface cooling pipe 50 Piping for cooling annular recess 51 Rib eject mechanism

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-134226 (JP, A) JP-A-6-87142 (JP, A) JP-A-2-243317 (JP, A) JP-A-5- 325254 (JP, A) JP-A-60-246039 (JP, A) Fukukaihei 2-50826 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 7/24 G11B 7 / 26

Claims (2)

(57) [Claims] 1. An optical disk in which at least a recording layer, a reflective layer and a protective layer are formed on the information surface side of one substrate of an optical disk used as a single plate, and the laser light is incident from the mirror surface side of the substrate. Specified width at the outer peripheral edge of the mirror surface side of
Optical disc having ribs formed by protruding a predetermined amount
The substrate is manufactured by injection molding or injection compression molding.
While being molded, an annular groove is formed at the outer peripheral end on the mirror surface side.
Located on the outer peripheral side of the annular groove and protruding by a predetermined amount to the mirror surface side.
Ring-shaped protrusions are formed, and the hard coat film is on the mirror surface side.
The rib portion is formed on one surface and
The hard coat film liquid for forming the coat film is formed in front of the annular groove and
Formed by being blocked by the annular protrusion
An optical disc characterized in that 2. The hard coat film comprises the rib portion.
Except for the film thickness, the film thickness becomes thinner on the outer peripheral side of the substrate.
The optical disc according to claim 1, wherein the optical disc has a distribution.
Ku.