JP2001338439A - Optical disk, its substrate and its molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make thin the thickness of an optical disk on which a clamp plate is disposed and make its outside diameter small. SOLUTION: A clamp holding face 14, a handling face 12 on the outer peripheral side of the face 14 and an information face 13 on the outer peripheral side of the face 14 are formed on a substrate 11. The face 12 is formed to have an inclined plane by inclining its outer peripheral side toward the face 13. The resin at the end of the face 12 on the inner peripheral side is melted/ deformed to form a projecting part 43 so that the clamp plate 41 can be held. Since the top of the inclined plane is deformed, the lager projecting part 43 can be formed. As a result, the optical disk and the substrate having thinner thickness and smaller outside diameter can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk used for recording or reproducing information, a substrate thereof, and a mold for molding the substrate.

[0002]

2. Description of the Related Art Conventionally, an optical disk and its substrate have been proposed in the form of a mini disk disclosed in Japanese Patent Application Laid-Open No. 5-303768.

FIG. 11 is a schematic sectional view of a conventional optical disk. 11, 101 is an optical disk substrate, 10
2 is a handling surface, 103 is an information surface, 104 is a clamp plate holding surface, 106 is a clamp plate, 107 is a groove, 108
Denotes an information recording layer, 109 denotes a protective coat, and 120 denotes a rotation center axis. The functions of the optical disk and the substrate configured as described above will be described below.

[0004] An optical disk has an information recording layer 1 on an information surface 103 formed on one main surface of a disk-shaped optically transparent substrate 101 made of polycarbonate, acrylic resin or the like.
As 08, a signal recording / reproducing layer or a reflective film is formed, and a protective coat 109 is formed thereon. A disk-shaped clamp plate 106 made of an iron plate or magnetic stainless steel is placed on the clamp plate holding surface 104 near the center of the substrate 101.
Is attached. The substrate 101 is rotated together with the disk table by magnetically attracting the clamp plate 106 onto a disk table fixed to the end of the spindle shaft of the recording / reproducing apparatus.

A method for holding the clamp plate 106 on the substrate 101 is disclosed in, for example, Japanese Patent Laid-Open No. 5-89529.
A method of performing welding by ultrasonic waves and a method of bonding with an ultraviolet curable resin are described.

[0006] The welding method using ultrasonic waves is performed as follows. As shown in FIG. 11, the clamp plate 106 is placed on the clamp plate holding surface 104. Next, an annular contact surface at the tip of the ultrasonic horn is pressed against the inner peripheral end of the handling surface 102 while pressing with a predetermined force. By emitting ultrasonic vibration in this state, the resin at the abutting portion is melted. Due to the pressing force of the ultrasonic horn, the molten resin is deformed, the abutting portion is displaced downward, and the molten resin protrudes on the wall surface connecting the clamp plate holding surface 104 and the handling surface 102, as shown in FIG. The projection 110 is formed. In FIG. 12, reference numeral 112 denotes a displacement surface formed by displacing a part of the inner surface of the handling surface 102 by bringing the contact surface of the ultrasonic horn into contact.
Here, the amount of protrusion of the protrusion 110 in the center direction corresponds to the amount of displacement of the displacement surface 112 with respect to the handling surface 102. As a result, since the outer peripheral side flat portion 106a of the outer periphery of the clamp plate 106 is sandwiched between the clamp plate holding surface 104 and the protruding portion 110, the clamp plate 106 is held so as not to fall off from the clamp plate holding surface 104.

[0007] The method of bonding with an ultraviolet curable resin is performed as follows. First, an ultraviolet curable resin is applied between the clamp plate holding surface 104 and the outer peripheral flat portion 106a of the outer periphery of the clamp plate 106. Next, ultraviolet rays are irradiated to cure the ultraviolet curable resin. Thus, the clamp plate holding surface 104 and the clamp plate 106 are bonded and fixed.

The substrate 101 is manufactured by injection molding.
The handling surface 102 functions as a suction surface for sucking the vacuum suction pad attached to the tip of the robot arm when the formed substrate 101 is taken out of the molding die using the robot arm. Handling surface 1
02 is limited by the outer peripheral end of the clamp plate holding surface 104, and the outer peripheral end of the handling surface 102 is
07 is limited by the inner peripheral end. The groove 107 reflects the shape of a mold part necessary to hold a stamper to be incorporated in the mold. An inner peripheral end of the information surface 103 (an inner peripheral end of a region where a groove or a pit is formed) is a groove 107.
Are arranged at a position separated from the outer peripheral end by a predetermined distance.

[0009]

In this optical disk and its substrate, it is required that the diameter of the disk be small and thin so that it can be applied to portable equipment.

However, as shown in FIG. 12, in an optical disk and its substrate in which the clamp plate 106 is sandwiched between the clamp plate holding surface 104 and the protrusion 110,
There are the following problems with respect to thinning. Substrate 101
In order to reduce the thickness, the distance in the thickness direction between the handling surface 102 and the clamp plate holding surface 104 needs to be reduced. Therefore, in FIG.
, The amount of displacement of the displacement surface 112 in the thickness direction becomes smaller. Therefore, the protrusion amount of the protrusion 110 is reduced. Thus, the reliability of holding the clamp plate 106 is reduced.

In order to solve this, as shown in FIG.
4 is formed, and the contact surface of the ultrasonic horn is brought into contact with the projection 114 to thereby handle the handling surface 102.
The protrusion 1
A method of increasing the amount of protrusion of the center 10 toward the center is conceivable. However, in this method, the inner peripheral end of the handling surface 102 is displaced radially outward due to the formation of the protrusion 114. In order to take out the substrate 101 from the injection mold, it is necessary to form a handling surface 102 larger than a predetermined area. Therefore, it is necessary to move the outer peripheral end of the handling surface 102 radially outward. As a result, the inner peripheral end and the outer peripheral end of the groove 107,
The inner peripheral end of the information surface 103 also needs to be sequentially moved outward in the radial direction, and there is a problem that the outer diameter of the optical disk becomes large in order to secure the same recording capacity.

On the other hand, in an optical disk and its substrate in which the clamp plate 106 is bonded and fixed to the clamp plate holding surface 104 by using an ultraviolet curable resin, the above-described problem does not occur when the size of the disk is made small and thin. . However, since the ultraviolet curable resin solidifies with the passage of time after the application of the droplet, for example, when the environmental temperature changes, the material of the clamp plate 106 and the material of the substrate 101 are different, and as a result, the thermal expansion coefficients of both materials are different. Are different, the substrate 1
01 was distorted, causing noise.

An object of the present invention is to solve the above problems and to provide an optical disk which can be reduced in size and thickness, a substrate thereof, and a molding die therefor. Another object of the present invention is to provide an optical disk in which no distortion remains on the substrate and the substrate.

[0014]

To achieve the above object, the present invention has the following constitution.

The first optical disk substrate of the present invention comprises a clamp plate, a clamp plate holding surface for holding the clamp plate by bringing an outer peripheral flat portion of the clamp plate into contact, and an outer peripheral side of the clamp plate holding surface. , And at least an information surface provided on the outer peripheral side of the handling surface, wherein at least a part of the handling surface is inclined with respect to the information surface.

According to the first optical disk substrate, the clamp plate can be held by melting and deforming the top of the inclined surface of the handling surface. As a result, the thickness of the optical disk and the substrate on which the clamp plate is installed can be reduced. Further, since the inner peripheral end of the information surface can be made closer to the rotation center axis, an optical disk and a substrate having a small outer diameter can be obtained.

In the first optical disk substrate, the thickness of the substrate in a region where the information surface is formed is 0.5 mm to 0.5 mm.
It is preferably in the range of 0.7 mm. If the thickness is smaller than this, the mechanical strength of the substrate is reduced, and the substrate is deformed, or the surface is run out during rotation. On the other hand, if the thickness is larger than this, the working distance (the distance between the objective lens and the optical disk surface) becomes smaller for an objective lens having an aperture ratio (NA) of 0.6 or higher. .

In the first optical disk substrate, it is preferable that an inclination angle of the handling surface with respect to the information surface is in a range of 2 ° to 10 °, and more preferably, in a range of 3 ° to 6 °. If the inclination angle is smaller than this, the inner end of the information surface must be arranged farther than the rotation center axis, and the recording capacity of the optical disk decreases or the disk diameter increases. If the inclination angle is larger than this, the substrate becomes partially thin, and the mechanical strength of the substrate decreases. In addition, operation failure of the suction pad for sucking the handling surface occurs.

In the first optical disk substrate, the width of the handling surface in the radial direction may be 1.8 mm or more.
It is preferably in the range of 2.5 mm. If the width of the handling surface in the radial direction is smaller than this, a malfunction of the suction pad that sucks the handling surface occurs. If the width is larger than this, the inner end of the information surface is located farther from the rotation center axis, so that the recording capacity of the optical disk is reduced or the disk diameter is increased. .

In the first optical disc substrate, it is preferable that a radial distance between an outer peripheral end of the handling surface and an inner peripheral end of the information surface is in a range of 2.0 to 4.0 mm. If the distance is smaller than this, the inner peripheral side movement position of the slider of the magnetic head is limited,
Recording capacity is limited. On the other hand, if the distance is longer than this, the inner peripheral end of the information surface is located farther from the rotation center axis, so that the recording capacity of the optical disk is reduced or the disk diameter is increased. .

In the first optical disk substrate, the surface of the clamp plate farthest from the clamp plate holding surface and the back surface of the optical disk substrate in a region where the clamp plate holding surface is formed are equidistant from each other. When a certain virtual plane is defined as a first center plane, and a virtual plane equidistant from the information surface and the back surface of the optical disk substrate in a region where the information surface is formed is defined as a second center plane, the first center plane is defined as Preferably, the distance from the second center plane is not greater than 0.3 mm. If the distance is larger than this, the thickness of the optical disk and the substrate becomes large, and it becomes difficult to make the drive device thinner than before.

In the first optical disk substrate, it is preferable that a distance between a plane including a circle formed by the deepest part of the handling surface and the information surface does not exceed 0.25 mm. If the distance is longer than this, the substrate is partially thinned, and the mechanical strength of the substrate is reduced.

In the first optical disk substrate, it is preferable that an outer peripheral end of the handling surface is lower than the information surface. Thereby, the stamper for molding the information surface can be held at the inner peripheral end.

Further, in the first optical disc substrate, a protruding portion whose upper surface is lower than the inner peripheral end of the handling surface and protrudes toward the center is formed inside the inner peripheral end of the handling surface. It is preferable that the clamp plate is regulated in the thickness direction by the protrusion and the clamp plate holding surface. Thus, the resin at the inner peripheral end of the handling surface is melted to form a protruding portion, thereby holding the clamp plate. Therefore, it is possible to provide an optical disk and a substrate that are less likely to be distorted by a change in temperature.

In the first optical disc substrate, it is preferable that a thickness of the clamp plate at the outer peripheral flat portion is smaller than a thickness of the clamp plate at an inner peripheral flat portion. The optical disc and the substrate can be thinned by attaching the clamp plate to the substrate while sandwiching the thin outer peripheral flat portion. Further, by making the inner peripheral side flat portion relatively thick, necessary magnetic attraction force can be secured.

In this case, the inner peripheral flat portion of the clamp plate may be formed by stacking a plurality of members. This makes it possible to easily and inexpensively manufacture the clamp plate having different thicknesses depending on locations.

According to a second optical disk substrate of the present invention, there are provided a clamp plate, a clamp plate holding surface for holding the clamp plate by bringing an outer peripheral flat portion of the clamp plate into contact, and an outer peripheral side of the clamp plate holding surface. And at least an information surface provided on the outer peripheral side of the handling surface, wherein the thickness of the clamp plate at the outer peripheral flat portion is smaller than the thickness of the clamp plate at the inner peripheral flat portion. It is characterized by.

According to the second optical disk substrate, the optical disk and the substrate can be reduced in thickness by attaching the clamp plate to the substrate while holding the thin outer peripheral side flat portion.
Further, by making the inner peripheral side flat portion relatively thick, necessary magnetic attraction force can be secured.

In the second optical disk substrate, the inner peripheral flat portion of the clamp plate may be formed by stacking a plurality of members. This makes it possible to easily and inexpensively manufacture the clamp plate having different thicknesses depending on locations.

A third optical disk substrate according to the present invention includes a clamp plate, a clamp plate holding surface for holding the clamp plate by bringing an outer peripheral flat portion of the clamp plate into contact, and an outer peripheral side of the clamp plate holding surface. And at least an information surface provided on an outer peripheral side of the handling surface, wherein a height of the clamp plate holding surface and a height of the information surface are different, and a substrate in a region where the information surface is formed is provided. The thickness of the substrate in the region where the clamp plate holding surface is formed is in the range of 0.75 to 1.25 times the thickness of the substrate, and the thickness of the substrate in the region where the information surface is formed is The thickness of the substrate in the region where the handling surface is formed is in the range of 0.75 to 1.25 times, and the thickness of the substrate in the region where the information surface is formed is Wall and the clamp plate retaining surface distance of 0.75 times to 1 of the wall connecting the rear surface of the back with the information surface connecting the lamp plate retaining surface and said handling surface.
It is within a range of 25 times.

According to the third optical disk substrate, it is possible to obtain an optical disk and a substrate with almost no mechanical distortion or optical distortion.

In the third optical disc substrate, it is preferable that at least a part of the handling surface is inclined with respect to the information surface. By melting and deforming the top of the slope of the handling surface,
The clamp plate can be held. As a result, the thickness of the optical disk and the substrate on which the clamp plate is installed can be reduced. Further, since the inner peripheral end of the information surface can be made closer to the rotation center axis, an optical disk and a substrate having a small outer diameter can be obtained.

Next, the optical disk according to the present invention is constructed as follows.
It is constituted by forming at least an information recording layer on the information surface of the third optical disc substrate.

In the above optical disk, a groove along a recording track or a groove constituting a recording track is formed on the information surface, and when the information recording layer is irradiated with light,
The amount of reflected light from the groove is preferably in the range of 0.3 to 0.8 with respect to the amount of reflected light from a flat portion other than the groove. If the ratio of the amount of reflected light is larger than this, the modulation rate of the signal in the groove becomes insufficient. On the other hand, if the ratio of the amount of reflected light is smaller than this, the signal cannot be sufficiently secured because the amount of reflected light in the groove is small.

In the above, it is preferable that the irradiation light has the same wavelength as the light used for recording and / or reproduction. This is to match the actual use conditions.

Next, the molding die according to the present invention comprises a disk-shaped fixed-side main body having a flat main surface, an inner stamper retainer fitted inside the fixed-side main body, and an inner side of the inner stamper retainer. The fixed-side bush fitted to the fixed-side main body, a disk-shaped movable-side main body installed at a position substantially opposed to the fixed-side main body at a predetermined interval, and fitted inside the movable-side main body, A movable bush installed at a position substantially opposed to the inner stamper retainer at a predetermined interval, and fitted inside the movable bush, and a predetermined interval from the fixed bush. At least a floating punch installed at a position substantially opposing to the other side, a surface of the inner stamper retainer opposing the movable side bush is inclined with respect to a main surface of the fixed side main body, and The floating punch surface facing the serial stationary bushing, from the main surface of the stationary body, and being located on said floating punch side.

Since the surface of the inner stamper retainer that faces the movable bush is inclined, an optical disk substrate having an inclined surface corresponding to the inclination can be formed. Also,
Since the surface of the fixed side bush is disposed near the floating punch, an optical disc substrate having a step for housing and holding the clamp plate can be formed. Accordingly, the clamp plate can be held by melting and deforming the top of the inclined surface of the optical disk substrate. As a result, an optical disk and a substrate having a small thickness and a small outer diameter can be obtained.

In the above molding die, it is preferable that the surface of the inner stamper retainer facing the movable bush is an inclined surface whose outer peripheral side is inclined closer to the movable bush than its inner peripheral side. Thereby, an optical disk substrate having an inclined surface with an inner peripheral surface raised can be formed.
Accordingly, the clamp plate can be held by melting and deforming the raised inner peripheral end.

In the above-mentioned molding die, a disk-shaped stamper is provided on the main surface of the fixed-side main body, and an outer peripheral end of a surface of the inner stamper press that faces the movable-side bush is the stamper surface. It is preferable that the inner bushing is located closer to the movable bush, and an inner peripheral end of a surface of the inner stamper retainer opposed to the movable bush is located farther from the movable bush than the outer peripheral end.
Thus, the stamper can be held at the outer peripheral end of the inner stamper retainer.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of an optical disc according to a first embodiment of the present invention in a thickness direction passing through a rotation center axis. However, it is shown in a state before a clamp plate described later is attached. In FIG. 1, 11 is an optical disk substrate, 12 is a handling surface, 13 is an information surface, 14
Is a clamp plate holding surface, 16 is a concave portion, 18 is an information recording layer,
19 is a protective coat, 10 is a rotation center axis. The function and manufacturing method of the optical disk substrate configured as described above will be described below.

The substrate 11 is an optically transparent disk made of polycarbonate, acrylic resin, or the like, and is usually manufactured by injection molding. On one main surface of the substrate 11, an information surface 13 in which grooves and / or pits are formed is provided. The grooves are formed along or to form the recording tracks. The pits are formed along the recording tracks. Substrate 11 in area where information surface 13 is formed
Is preferably in the range of 0.5 to 0.7 mm.

The information recording layer 18 is provided on the information surface 13 of the substrate 11.
An optical disk is obtained by forming the protective coat 19 and the protective coat 19 in this order.

In the case of a read-only optical disk, a reflective film formed by depositing Al, Au, Ag, or an alloy thereof by means of, for example, sputtering can be used as the information recording layer 18. In the case of an optical disk capable of recording and reproduction, a signal recording / reproduction layer formed by forming a magneto-optical recording film or a phase change recording film by means such as sputtering, or a dye film by means of spin coating or the like. Can be used as the information recording layer 18.

When the surface of the information recording layer 18 is irradiated with light having a wavelength used for recording or reproduction of the optical disc,
It is preferable that the amount of reflected light from the groove formed on the information surface 13 is in the range of 0.3 to 0.8 with respect to the amount of reflected light from the flat surface (a flat region where no groove and pit are formed).

Next, a method for manufacturing the substrate 11 will be described. 2 is a cross-sectional view of a main part of a molding die for injection molding used when manufacturing the substrate 11, and FIG. 3 is a cross-sectional view of a main part showing a mold opening state of the die during an injection molding process. .

In FIG. 2, reference numeral 21 denotes a nozzle of an injection molding machine (not shown) for injecting a molten resin at a high temperature.
2 is a sprue bush against which the nozzle 21 abuts, 23 is a fixed bush located on the outer peripheral side of the sprue bush 22, 24 is an inner stamper presser located outside the fixed bush 23, and 25 is an outer presser of the inner stamper presser 24. The fixed-side main body 26 is a fixed-side cradle.
The fixed-side bush 23 and the sprue bush 22 are held by stepped portions formed on the inner peripheral side of the fixed-side receiving stand 26, and the inner stamper retainer 24 and the fixed-side The main body 25 is attached.
The fixed-side receiving base 26 is connected to a fixed-side platen (not shown) of the injection molding machine at the other surface (upper surface). Reference numeral 27 denotes a stamper in which a groove or a pit is engraved on one main surface. The inner peripheral end of the stamper is locked by a claw of an inner stamper retainer 24 so that the surface opposite to the main surface is fixed. It is fixed and held while being in contact with the main body 25.

Reference numeral 31 denotes a sprue cut punch provided at a position facing the sprue bush 22; 30 denotes an ejector provided inside the sprue cut punch 31;
2 is a floating punch installed on the outer peripheral side of the sprue cut punch 31; 33 is a floating punch 32
A movable bush 34 is provided on the outer peripheral side of the movable bush 33, a movable main body located on the outer peripheral side of the movable bush 33, and a movable base 35 is provided. One surface (upper surface) of the movable-side receiving base 35
Supports the movable-side bush 33 and the movable-side main body 34.
The movable receiving stand 35 is connected to a movable platen (not shown) of the injection molding machine on the other surface (lower surface).

Numeral 36 denotes a cavity ring disposed on the outer peripheral end of the movable body 34, and numeral 37 denotes a fixed bush 23, an inner stamper retainer 24, a stamper 27, a cavity ring 36, a movable body 34, a movable bush 33 and a floating member. The cavity is a space surrounded by the punch 32 and the sprue cut punch 31. Reference numeral 38 denotes a resin passage connecting the nozzle 21 and the cavity 37, and is formed by being surrounded by the sprue bush 22 and the sprue cut punch 31.

In FIG. 3, reference numeral 400 denotes an arm base, and 401 denotes a robot arm. Reference numeral 402 denotes a robot body in which a driving mechanism and a control device are incorporated, and supports a robot arm 401. 403 is an arm base 40
0, a suction pad having a vacuum mechanism or the like; 404, a sprue solidified in the resin passage 38;
5 is a sprue chuck. 11 is a molded substrate. The same parts as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

Next, a method of manufacturing the substrate 11 by injection molding will be described with reference to FIGS.

The resin (for example, polycarbonate) melted by the injection molding machine with respect to the mold in the clamped state with a force of about several tons shown in FIG. Is injected through the resin passage 38 into the cavity 37 through the gap between the sprue cut punch 31 and the fixed bush 23,
Is filled with resin. Sprue cut punch 31 after filling
Moves to the sprue bush 22 side, the sprue cut punch 31 functions as a male blade, and the fixed side bush 22 functions as a female blade to separate the resin passage 38 from the cavity 37.

The pressure in the cavity 37 and the temperature in the cavity 37 are adjusted appropriately, and after the resin in the resin passage 38 and the resin in the cavity 37 have solidified to some extent, the stamper 27 and the cavity 37
The mold is opened by performing an air blow or the like for release between the resin inside the mold. FIG. 3 shows a state in which the mold is opened. The resin (substrate 11) in the cavity 37 is in close contact with the movable body 34, and the resin in the resin passage 38 is solidified to form the sprue cut punch 31 as a sprue 404. Remains on top. In this state, the robot arm 401 for taking out the resin is inserted as illustrated.

Cavity 3 of inner stamper retainer 24
Since the surface on the 7th side is inclined with respect to the main surface of the stamper 27 on which grooves and pits are imprinted, the suction pad 40
3 is also installed inclining according to the inclination. Suction pad 4
03, the substrate 11 is sucked and held under reduced pressure, and the sprue chuck 405 holds the sprue 404. Substrate 1
1 and the ejector 30 is protruded toward the sprue bush 22 at the same time as air blowing between the movable side main body 34 and
The robot arm 401 is slightly moved to the fixed body 25 to separate the substrate 11 and the sprue 404 from the mold.
Next, the robot arm 401 is swung largely in a horizontal plane, and the substrate 11 and the sprue 404 are taken out of the mold to take out the substrate 11.

After that, as described above, a signal recording / reproducing layer and a reflective film are formed on the information surface 13 of the substrate 11 to form an information recording layer 18, and then a protective coat 19 is formed.

FIG. 4 is a cross-sectional view in the thickness direction of the optical disk according to the first embodiment of the present invention passing through the rotation center axis.
In FIG. 4, reference numeral 41 denotes a clamp plate, 41a denotes an outer peripheral side flat portion of the clamp plate 41, 42 denotes a displacement surface, and 43 denotes a protruding portion. 11 is a substrate, 12 is a handling surface, 13 is an information surface, 14 is a clamp plate holding surface, 16 is a concave portion, 18 is an information recording layer, and 19 is a protective coat, and these have the same functions as those shown in FIG. Have

The clamp plate 41 is a disk-shaped plate made of a material such as an iron plate or magnetic stainless steel.
It is mounted on one clamp plate holding surface 14. A magnet is attached to a disk table fixed to the tip of the spindle shaft of the recording / reproducing apparatus. By mounting the clamp plate 41 on the disk table, the clamp plate 41 is magnetically attracted to the magnet. As a result, the substrate 11 is rotated with the disk table. At the center of the disk table, a pole for positioning the disk and a magnet device for performing magnetic attraction are protrudingly mounted. For this reason, the central portion of the clamp plate 41 is formed so as to protrude in one direction like a mountain-shaped hat. Such a shape is manufactured using a sheet metal pressing process or the like.

Next, the process of installing the clamp plate 41 is shown in FIG.
This will be described with reference to FIG. First, the clamp plate 41 is mounted on the clamp plate holding surface 14 in FIG. 1 such that the outer peripheral side flat portion 41a corresponding to the hat flange comes into contact. Next, an annular contact surface at the tip of a horn of an ultrasonic vibrator (not shown) vibrating at an appropriate vibration amplitude, vibration frequency, and vibration direction is provided on the inner peripheral end of the handling surface 12. Abut with appropriate abutment force. Then, the resin at the abutting portion is melted and deformed by frictional heat generated by ultrasonic vibration. By this operation, as shown in FIG. 4, the portion of the handling surface 12 where the ultrasonic horn is abutted is deformed and the displacement surface 42 is deformed.
Are formed, and at the same time, the molten resin moves in the direction of the rotation center axis 10 to form the protrusion 43. Clamp plate 41
The position is regulated in the thickness direction by the protrusion 43 and the clamp plate holding surface 14, and is held on the substrate 11. A predetermined gap is provided between the clamp plate 41 and the substrate 11 in the radial direction and the thickness direction in consideration of the difference in the coefficient of thermal expansion between the two.

To make the optical disk thin, the back surface (first lower surface 45) of the clamp plate holding surface 14 and the protective coat 1
It is necessary to reduce the distance in the thickness direction from the surface of No. 9. In order to reduce the diameter of the optical disk, the information surface 1
It is necessary to reduce the distance between the inner peripheral end of No. 3 and the rotation center axis 10. Since the thickness of the protective coat 19 is at most about 0.05 mm, there is little room for contributing to the thinning of the optical disk. Therefore, substantially, the first lower surface 45 and the information surface 1
It is necessary to reduce the distance in the thickness direction with respect to 3.
Further, the uppermost end surface 41 b of the clamp plate 41 and the first lower surface 4
5, a virtual second center plane equidistant from the information surface 13 and the back surface (second lower surface 46) of the substrate 11 in the region where the information surface 13 is formed. It is preferable that the distance in the thickness direction from the surface 72 is not larger than 0.3 mm in order to form a thin optical disk.

The inner diameter of the optical disk substrate 11 corresponding to the inner peripheral end of the clamp plate holding surface 14 is usually determined by the motor provided in the recording / reproducing device, the size of the positioning member of the disk table, the size of the magnet device, and the like. The radial width of the clamp plate holding surface 14 is usually
1 is determined by the shape and dimensions. Handling surface 1
The size of 2 is restricted by the size and arrangement of the suction pads 403, and is determined in consideration of the weight of the substrate and the acceleration during handling. In the embodiment of the present invention, the width of the handling surface 12 in the radial direction is 1.8 mm to 2.5 mm.
It is preferred that The outer peripheral end of the recess 16 (this is
(Coincides with the outer peripheral end of the handling surface 12) and the information surface 1
The distance in the radial direction from the inner peripheral end of the light-receiving layer 3 is determined by, for example, the manufacturing allowance of the signal recording / reproducing film and the reflection film, the manufacturing allowance of the protective coat 19, and the like.
Is preferably between 2.0 mm and 4.0 mm in the radial direction between the outer peripheral end of the information surface 13 and the inner peripheral end of the information surface 13. In the embodiment of the present invention, the information surface 13 is moved from the inner peripheral end of the information surface 13 to the information surface 13.
Is preferably in the range of 12 to 14 mm, and the radial distance from the outer peripheral end of the information surface 13 to the outer peripheral end of the substrate 11 is 1.0 to 3.0 mm.
It is preferably in the range of 0 mm. In the present invention, the inner (outer) peripheral end of the information surface 13 means the inner (outer) peripheral end in the radial direction of the region on the main surface of the substrate 11 in which the grooves or pits are formed. .

The concave portion 16 formed on the outer peripheral end of the handling surface 12 reflects the shape of the claw (locking portion) for the inner stamper holder 24 of the molding die to hold the stamper 27. It is a thing. If the holding strength of the inner stamper retainer 24 with respect to the stamper 27 is to be increased, the depth of the concave portion 16 increases. However, in order to secure the mechanical strength of the substrate 11, it is desirable that the depth of the concave portion 16 is small. For this reason, in the embodiment of the present invention, it is preferable that the depth of the concave portion 16 (the height difference with respect to the information surface 13) does not exceed 0.25 mm.

Under the above-described various constraints, in order to reduce the diameter and thickness of the optical disk substrate, in this embodiment, as shown in FIG. It is inclined with respect to the information surface 13 in such a manner.
The outer peripheral side end is made to coincide with the concave portion 16.

Since the handling surface 12 is inclined so that the inner peripheral end is higher, when the displacement surface 42 is formed to hold the clamp plate 41 as shown in FIG.
The protrusion 43 having a sufficient protrusion amount to hold the clamp plate 41 can be formed. Therefore, it is not necessary to form the protrusion 114 as shown in FIG.
It is not necessary to move the outer peripheral end of the outer side in the radial direction. Therefore, the radial distance between the outer peripheral end of the clamp plate holding surface 14 and the inner peripheral end of the information surface 13 can be reduced.
The optical disc can be reduced in diameter.

Further, since the protrusion 43 having a sufficient protrusion amount can be formed, the thickness of the substrate 11 in the region where the information surface 13 is formed can be reduced.

Further, the outer peripheral end of the handling surface 12 is made the deepest, and the concave portion 16 serving also as the handling surface 12 is formed there.
Is provided, it is possible to secure the strength of the claw for holding the stamper 27 of the inner stamper retainer 24.

As described above, it is possible to provide an optical disk and a substrate thereof that can be reduced in size and thickness.

In the above, in the sectional view taken along a plane passing through the rotation center axis of the optical disk, the inclination angle θ of the handling surface 12 with respect to the information surface 13 is preferably 2 ° to 10 °,
3 ° to 6 ° is more preferred.

FIGS. 5A, 5B, and 6 show specific embodiments of the optical disk. FIG. 5A is a plan view of the optical disc, and FIG.
B is a cross-sectional view thereof, and FIG. 6 is an enlarged cross-sectional view of a portion VI of FIG. 5B. 5A, FIG. 5B, and FIG. 6, the outer diameter D0 of the optical disk is 50.8 mm, and the diameter of the circle drawn by the outer peripheral end of the first lower surface 45 (“outer peripheral end diameter”; hereinafter the same) D45OUT = 1
4.5 mm, diameter of a circle drawn by the inner peripheral end of the first lower surface 45 (“inner peripheral end diameter”, the same applies hereinafter) D45IN = 11 mm, outer peripheral end diameter D13OUT of the information surface 13 = 47.6 mm, information Inner peripheral end diameter D13IN of surface 13 = 22 mm, handling surface 1
2 outer peripheral end diameter D12OUT = 18 mm, handling surface 1
2, inner diameter D12IN = 13.3 mm, clamp plate 41
The central opening diameter D41 is 4 mm. Distance T0 = 1.8 m between uppermost end surface 41b of clamp plate 41 and first lower surface 45
m, the distance T1 between the surface of the protective coat 19 and the second lower surface 46
= 0.6 mm, the distance L0 between the virtual first center plane 71 and the virtual second center plane 72 = 0.1 mm, and the step L2 in the thickness direction between the first lower surface 45 and the second lower surface 46. = 0.7m
m, the inclination angle θ of the handling surface 12 with respect to the recording surface 13
= 5.6 degrees.

In the above description, the example in which the stamper 27 is installed on the fixed-side platen side is shown. However, the stamper 27 can be realized by installing a stamper on the movable-side platen side.

As shown in FIG. 7, the surface 47 facing the handling surface 12 may be inclined in accordance with the inclination of the handling surface 12, and as shown in FIG.
The surface of the movable bush 33 on the side of the cavity 37 may be inclined in accordance with the inclination of the surface of the inner stamper retainer 24 on the side of the cavity 37. In such a case, the same effect as described above can be expected. .

(Embodiment 2) FIG. 9 is a cross-sectional view in the thickness direction of an optical disk according to Embodiment 2 of the present invention passing through a rotation center axis. In FIG. 9, reference numeral 51 denotes a clamp plate, 52 denotes a displacement surface, 53 denotes a protruding portion, 54 denotes a handling surface substantially parallel to the information surface 13, and 55 denotes a substrate. Reference numeral 14 denotes a clamp plate holding surface, reference numeral 18 denotes an information recording layer, and reference numeral 19 denotes a protective coat, which have the same functions as those described in the first embodiment.

The step of molding the substrate 55 by injection molding is the same as that of the first embodiment, although there are some differences in the shape of the substrate.

The clamp plate 51 has a hat-shaped cap similar to the clamp plate 41 shown in the first embodiment. However, unlike the clamp plate 41 of the first embodiment, in the clamp plate 51 of the present embodiment, the thickness of the outer peripheral flat portion 51a corresponding to the hat flange is the thickness of the uppermost end surface 51b (the inner peripheral flat portion). Thinner than thickness. Preferably, the thickness of the outer peripheral side flat portion 51a is １ ／ to ／ of the thickness of the inner peripheral side flat portion.
It is. Specifically, the thickness of the inner peripheral side flat portion is 0.2 to
It is preferably 0.5 mm, especially 0.3 mm,
It is preferable that the thickness of the outer peripheral side flat portion 51a be 0.1 to 0.15 mm. Such a clamp plate 51 can be manufactured using a multi-stage drawing process of a sheet metal.

Such a clamp plate 51 is attached to the substrate 55 in the same manner as in the first embodiment. That is, first, the clamp plate 51 is placed on the clamp plate holding surface 14.
Of the clamp plate 51 so that the outer peripheral side flat portion 51a of the
With. Next, the annular contact surface at the tip of the horn of the ultrasonic vibrator is brought into contact with the inner peripheral end of the handling surface 54, and the resin of the contact portion is melted by frictional heat generated by the ultrasonic vibration and deformed. Let it. As a result, as shown in FIG. 9, the portion where the ultrasonic horn abuts is deformed to form the displacement surface 52, and at the same time, the molten resin is
The projection 53 is formed by moving in the direction of 0.

The functions of the optical disk and the substrate configured as described above will be described below.

The clamp plate 51 is a member necessary for holding the optical disk on the disk table of the recording / reproducing apparatus by magnetic attraction. Magnetic force (clamping force) exceeding a specified value
In order to obtain the thickness, it is necessary that the plate thickness of the inner peripheral flat surface of the clamp plate 51 to be magnetically attracted is not less than a certain thickness. If the outer peripheral flat portion 51a of the clamp plate 51 that is not magnetically attracted is made thicker so as to have the same thickness as the inner peripheral flat portion, the interval between the clamp plate holding surface 14 and the protruding portion 53 is set accordingly. Need to be bigger. On the other hand, a protrusion 5 having a protrusion amount necessary to hold the clamp plate 51 is provided.
In order to form 3, the displacement surface 53 and the handling surface 5
4 has a lower limit value. Therefore, it is necessary to increase the distance between the clamp plate holding surface 14 and the handling surface 54, and the thickness of the substrate 55 cannot be reduced.

Therefore, in the present embodiment, the clamp plate 5
The thickness of the outer peripheral flat portion 51a is smaller than the thickness of the inner peripheral flat portion. As a result, the distance between the clamp plate holding surface 14 and the protruding portion 53 can be reduced even if a gap considering the difference in the amount of thermal expansion is provided. Accordingly, the distance between the clamp plate holding surface 14 and the handling surface 54 can be reduced while forming the protrusion 53 having a protrusion amount necessary to hold the clamp plate 51, and the substrate 55 and the optical disk Can be made thinner.

As described above, unlike the handling surface 12 of the first embodiment, the handling surface 54 of the present embodiment is not inclined with respect to the information surface 13. However, the inclined handling surface 12 shown in the first embodiment.
It is also possible to apply the clamp plate 51 of the present embodiment to the substrate 11 provided with.

In the above description, an example is shown in which the clamp plate 51 is formed by a multi-step drawing press process, but the method of manufacturing the clamp plate 51 is not limited to this. For example,
By laminating multiple members using welding, etc.,
A relatively thick inner peripheral flat portion can be obtained.

(Embodiment 3) FIG. 10 is a sectional view of a main part of a molding die for injection molding used when manufacturing an optical disk substrate according to Embodiment 3 of the present invention. FIG. 10 also shows the flow of the resin injected into the cavity 37. In FIG. 10, a solid line 60 indicates the state of resin filling and flow, and a dotted line 61 indicates a line along the vicinity of the center of the resin flow. Reference numeral 11 denotes a substrate, 12 denotes a handling surface, 13 denotes an information surface, 14 denotes a clamp plate holding surface, and 16 denotes a concave portion, which have the same functions as those shown in FIG. Further, 21 is a nozzle, 22 is a sprue bush, 23 is a fixed side bush, 24 is an inner stamper holder, 25 is a fixed side main body, 26 is a fixed side pedestal, 27 is a stamper, 30 is an ejector, 32 is a floating punch, 33 Is a movable side bush, 34 is a movable side main body, 35 is a movable side pedestal, 36 is a cavity ring, 37 is a cavity, and 38 is a resin passage, which have the same functions as those shown in FIG. .

The resin (for example, polycarbonate) melted by the injection molding machine with respect to the mold in the mold clamped state with a force of about several tons shown in FIG. Is injected through the resin passage 38 into the cavity 37 through the gap between the sprue cut punch 31 and the fixed side bush 23, and the cavity 37 is filled with the resin. At this time, the resin is gradually filled as indicated by a solid line 60 from the resin passage 38 at the center toward the outer periphery. In parallel with this, the resin is gradually cooled from the resin near the mold surface and solidified. Therefore, the gap through which the resin can flow gradually narrows and approaches the vicinity of the dotted line 61. In the first stage of filling, the resin near the surface of the fixed bush 23 and the resin near the surface of the floating punch 32, which are near the resin passage 38, are cooled and gradually solidified. The same cooling and solidification occurs in the order of expanding toward the outer periphery of the cavity 37.

Focusing on the front end face in the traveling direction of the resin filled in the cavity 37, the distance from the resin passage 38 to the front end face gradually increases as the resin filling progresses. The total area of the surface gradually increases. What is important here is that the rate of increase in the total area of the front end face changes little from the start to the end of filling. A large change in the increasing rate means that the filling rate of the resin greatly differs depending on the location, and unevenness occurs in the cooling process, and mechanical distortion or optical distortion remains on the obtained substrate 11. I do. The fact that the increase speed is constant without change means that the gap between the opposing walls forming the cavity 37 in the sectional view shown in FIG. 10 hardly changes in the direction in which the resin travels.

The present inventors have studied many shapes of the cavity 37 from such a viewpoint. As a result, the surface of the stamper 27 forming the information surface 13 and the movable body 3
When the gap between the opposing wall surfaces at each location where the resin flows is within the range of 0.7 to 1.25 times the gap between the resin and the surface of the resin 4, the unevenness of the cooling process can be ignored. It has been found that a substrate can be obtained which is small and hardly has any mechanical distortion or optical distortion.

In other words, it is preferable that the following condition is satisfied for the substrate 11 shown in FIGS. 1 and 4 which is finally obtained. First, the thickness (the distance between the information surface 13 and the second lower surface 46) of the substrate 11 in the region where the information surface 13 is formed is compared with the thickness (the distance between the information surface 13 and the second lower surface 46) of the substrate 11 in the region where the clamp plate holding surface 14 is formed. The distance between the clamp plate holding surface 14 and the first lower surface 45) is preferably in the range of 0.75 times to 1.25 times. Second, the thickness of the substrate 11 in the region where the handling surface 12 is formed (the distance between the handling surface 12 and the second lower surface 46) is set to be smaller than the thickness of the substrate 11 in the region where the information surface 13 is formed.
It is preferably within the range of 75 times to 1.25 times. Third, with respect to the thickness of the substrate 11 in a region where the information surface 13 is formed, a cylindrical surface connecting the clamp plate holding surface 14 and the handling surface 12 and a back surface (first lower surface 45) of the clamp plate holding surface 14 And the back surface of the information surface 13 (second lower surface 46)
Is preferably in the range of 0.75 times to 1.25 times.

In the above description, the mold for molding the substrate 11 shown in the first embodiment in which the handling surface 12 is inclined with respect to the information surface 13 has been described as an example. The above-described design concept can be similarly applied to a mold for molding the substrate 55 shown in the second embodiment, which is substantially parallel to the thirteenth embodiment.

[0086]

As described above, according to the present invention, by providing the handling surface inclined with respect to the information surface, the thickness of the optical disk on which the clamp plate is installed can be reduced, and the inner surface of the information surface can be reduced. The end position can be set near the rotation center axis, and an optical disc having a small outer diameter can be obtained. Furthermore, by limiting the range of the thickness of the substrate, an optical disk with almost no mechanical distortion or optical distortion can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a state of an optical disc according to a first embodiment of the present invention before a clamp plate is attached.

FIG. 2 is a sectional view of a main part of a molding die for manufacturing the optical disk substrate shown in FIG.

FIG. 3 is a diagram illustrating a method of molding a substrate using the molding die of FIG. 2;
It is principal part sectional drawing which showed the state which opened the metal mold | die.

FIG. 4 is a schematic sectional view of the optical disc according to the first embodiment of the present invention.

5A and 5B are diagrams showing an optical disc according to an example of the first embodiment of the present invention, FIG. 5A is a plan view thereof, and FIG. 5B is a cross-sectional view thereof.

FIG. 6 is an enlarged sectional view of a portion VI of FIG. 5B.

FIG. 7 is a schematic sectional view of another optical disk according to the first embodiment of the present invention.

8 is a cross-sectional view of a main part of a molding die for manufacturing the optical disc substrate shown in FIG.

FIG. 9 is a schematic sectional view of an optical disc according to a second embodiment of the present invention.

FIG. 10 is a fragmentary cross-sectional view of a molding die for manufacturing the optical disc substrate according to the third embodiment of the present invention;

FIG. 11 is a schematic sectional view of a conventional optical disc.

FIG. 12 is a schematic sectional view illustrating a method of attaching a clamp plate to a conventional optical disc.

FIG. 13 is a schematic cross-sectional view illustrating another method of mounting a clamp plate on a conventional optical disc.

[Explanation of symbols]

 11, 55, 101 Optical disc substrate 12, 54, 102 Handling surface 13, 103 Information surface 14, 104 Clamp plate holding surface 16 Concave portion 18, 108 Information recording layer 19, 109 Protective coat 10, 120 Rotation center axis 21 Nozzle 22 Sprue bush 23 Fixed side bush 24 Inner stamper retainer 25 Fixed side main body 26 Fixed side receiving stand 27 Stamper 30 Ejector 31 Sprue cut punch 32 Floating punch 33 Movable side bush 34 Movable side main body 35 Movable side receiving base 36 Cavity ring 37 Cavity 38 Resin passage 400 Arm base 401 Robot arm 402 Robot body 403 Suction pad 404 Sprue 405 Sprue chuck 41, 51, 106 Clamp plate 41a, 51a, 106a Outer side flat Part 41b, 51b Uppermost end surface 42, 52, 112 Displacement surface 43, 53, 110 Projecting portion 45 First lower surface 46 Second lower surface 60 Resin filling and flow line 61 Flow center line 71 Virtual first center surface 72 Virtual Second center plane 107 Groove 114 Projection

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomio Yamamoto 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Terms (Reference) 5D029 KB12 PA06 5D121 AA02 DD05 DD18

Claims (21)

[Claims] A clamp plate, a clamp plate holding surface for holding the clamp plate by abutting an outer peripheral flat portion of the clamp plate, a handling surface provided on an outer peripheral side of the clamp plate holding surface, An optical disc substrate, comprising: at least an information surface provided on an outer peripheral side of a handling surface, wherein at least a part of the handling surface is inclined with respect to the information surface. 2. The optical disk substrate according to claim 1, wherein a thickness of the substrate in a region where the information surface is formed is in a range of 0.5 mm to 0.7 mm. 3. The optical disk substrate according to claim 1, wherein an inclination angle of the handling surface with respect to the information surface is in a range of 2 ° to 10 °. 4. The optical disc substrate according to claim 1, wherein a width of the handling surface in a radial direction is in a range of 1.8 mm to 2.5 mm. 5. A radial distance between an outer peripheral end of the handling surface and an inner peripheral end of the information surface is 2.0 to 4.0 mm.
The optical disc substrate according to claim 1, wherein 6. A virtual first center plane equidistant from a surface of the clamp plate farthest from the clamp plate holding surface and a back surface of the optical disk substrate in a region where the clamp plate holding surface is formed. The optical disk substrate according to claim 1, wherein a distance between the information surface and a virtual second center plane equidistant from a back surface of the optical disk substrate in a region where the information surface is formed is not larger than 0.3 mm. 7. The optical disc substrate according to claim 1, wherein a distance between a plane including a circle formed by the deepest part of the handling surface and the information surface does not exceed 0.25 mm. 8. The optical disk substrate according to claim 1, wherein an outer peripheral end of the handling surface is lower than the information surface. 9. A protruding portion whose upper surface is lower than the inner peripheral end of the handling surface and protrudes in the center direction is formed inside the inner peripheral end of the handling surface, wherein the protruding portion and the clamp plate holding surface are formed. 2. The optical disc substrate according to claim 1, wherein the clamp plate is restricted in a thickness direction. 10. The optical disk substrate according to claim 1, wherein the thickness of the clamp plate at the outer peripheral flat portion is smaller than the thickness of the clamp plate at the inner peripheral flat portion. 11. The optical disk substrate according to claim 10, wherein the inner peripheral flat portion of the clamp plate is formed by stacking a plurality of members. 12. A clamp plate, a clamp plate holding surface for holding the clamp plate by contacting an outer peripheral flat portion of the clamp plate, a handling surface provided on an outer peripheral side of the clamp plate holding surface, An optical disc substrate comprising at least an information surface provided on an outer peripheral side of a handling surface, wherein a thickness of the clamp plate at the outer peripheral flat portion is smaller than a thickness of an inner peripheral flat portion of the clamp plate. 13. The optical disk substrate according to claim 12, wherein the inner peripheral flat portion of the clamp plate is formed by stacking a plurality of members. 14. A clamp plate, a clamp plate holding surface for holding the clamp plate by contacting an outer peripheral flat portion of the clamp plate, a handling surface provided on an outer peripheral side of the clamp plate holding surface, At least an information surface provided on an outer peripheral side of a handling surface, wherein the height of the clamp plate holding surface and the height of the information surface are different, and the clamp is applied to a thickness of a substrate in a region where the information surface is formed. The thickness of the substrate in the region where the plate holding surface is formed is in the range of 0.75 to 1.25 times, and the handling surface is formed with respect to the thickness of the substrate in the region where the information surface is formed. The thickness of the substrate in the region where the information surface is formed is in the range of 0.75 to 1.25 times, and the clamp plate holding surface and the c An optical disc substrate, wherein a distance between a wall surface connecting the dolly surface and a wall surface connecting the back surface of the clamp plate holding surface and the back surface of the information surface is within a range of 0.75 to 1.25 times. . 15. The optical disc substrate according to claim 14, wherein at least a part of the handling surface is inclined with respect to the information surface. 16. An optical disc having at least an information recording layer formed on the information surface of the optical disc substrate according to claim 1, 12, or 14. 17. A groove along a recording track or a groove constituting a recording track is formed on the information surface, and when light is irradiated on the information recording layer, the amount of light reflected from the groove is other than that of the groove. 17. The optical disk according to claim 16, wherein the amount of light reflected from the flat portion is in a range of 0.3 to 0.8. 18. The optical disk according to claim 17, wherein the light to be irradiated is light having the same wavelength as light used for recording and / or reproduction. 19. A disk-shaped fixed body having a flat main surface, an inner stamper retainer fitted inside the fixed body, and a fixed bush fitted inside the inner stamper retainer. A disk-shaped movable-side main body installed at a position substantially opposed to the fixed-side main body at a predetermined distance, fitted inside the movable-side main body, and predetermined with respect to the inner stamper presser; A movable bush installed at a position substantially opposed to the fixed bush; and a movable bush installed at a position substantially opposed to the fixed bush at a predetermined interval. A surface facing the movable bush of the inner stamper retainer is inclined with respect to a main surface of the fixed body, and the fixed bush is The floating punch surface facing is from the major surface of the stationary body, the molding die, characterized in that located on the floating punch side. 20. The surface of the inner stamper retainer that faces the movable bush is an inclined surface whose outer peripheral side is inclined toward the movable bush from the inner peripheral side.
10. The molding die according to 9. 21. A disk-shaped stamper is provided on a main surface of the fixed-side main body, and an outer peripheral end of a surface of the inner stamper holder facing the movable-side bush is closer to the movable-side bush than the stamper surface. 20. The molding die according to claim 19, wherein an inner peripheral end of a surface of the inner stamper retainer that faces the movable bush is located farther from the movable bush than the outer peripheral end.