JPH05174432A - Device for producing 2p substrate for optical disk and 2p substrate produced by the device - Google Patents

Abstract

PURPOSE:To eliminate a defective tracking while an optical disk is rotated faster than a normal speed. CONSTITUTION:The production device of an optical disk 2P substrate consists of a stamper 1, a glass discord pressing plate facing the stamper, a driving mechanism which presses the pressing plate and the stamper and a motor which is a driving power source of the driving mechanism. Moreover, more than three reference members 2, which are located in the periphery of the stamper and at an equal distance L1 from the track circle center (where L1 is larger than a radius r of the substrate) are provided. By this arrangement, a high quality 2P substrate is produced with a very small deviation between the center of the rotation and the centroid of the disk (a second amount of eccentricity is less than 10mum). Having this arrangement, a tracking defect is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk 2P substrate manufacturing apparatus and an optical disk 2P substrate manufactured therefrom.

[0002]

2. Description of the Related Art Recently, an optical information recording / reproducing system having characteristics such as high density, large capacity, high access speed, and high recording / reproducing speed has been put into practical use, and further research and development for further improvement have been made. It has become. The optical information recording medium used for this has a disc shape and is also called an optical disc. Optical disks are roughly classified into a read-only type and a recordable type. In the read-only type, protrusions or depressions called pits are formed on the track in dots on the surface of the substrate on the disk having a smooth surface. The tracks are formed in a concentric shape or a spiral shape when the disk plane is viewed from the vertical direction. However, in the read-only type, there are generally no explicit tracks. This is because tracking can be performed by relying on pits. However, a track clearly shown in the form of a groove or a land described later may be provided. Information is represented by the presence or absence of pits or their length. One pit has a fine dimension of, for example, width 0.5 μm × length 0.9 to 3 μm × depth or height 0.1 μm. The track interval is also minute, for example, 1.6 μm. In practice, a vapor deposition film (reflection film) of metal such as Al or Au is formed on the substrate surface in order to increase the reflectance. Therefore, here, the one excluding the reflection film is referred to as an “optical disk substrate”. It has pits on the surface.

The recordable type is roughly classified into a write-once type (also referred to as a write-once or a DRAW) that can be recorded only once and a rewritable type that can repeatedly record and erase.
The former has a recording layer made of Te, Te-C, Te-Se-Pb, a resin containing a dye, or the like, and a hole (pit) is formed by irradiating the recording layer with a laser beam. The latter is currently put into practical use as a phase change type (crystalline-amorphous) and a magneto-optical type. The magneto-optical type has a recording layer made of a magnetic thin film that can be perpendicularly magnetized. Once the direction of magnetization is aligned upward or downward (called initialization), this is irradiated with a laser beam and at the same time the recording magnetic field is changed. Is applied to form a mark whose magnetization direction is reversed. Information is represented by the presence or absence of this mark or its length.
When the mark is irradiated with linearly polarized light (weak laser beam),
The plane of polarization of reflected light or transmitted light is rotated by θ _k . This is called the Kerr effect or Faraday effect. On the other hand, the "ground" part other than the mark rotates -θ _k . Therefore, when the reflected light or the transmitted light is passed through a polarizer (detector), the mark can be captured as a change in the light amount. This reproduces the information. A typical magneto-optical recording layer is a rare earth-transition metal amorphous alloy such as Tb.
Fe, TbFeCo, GdFe, GdCo, DyFe,
A single layer film such as GdTbFe, GdTbCo or GdFe /
There are two-layer films such as TbFe and GdFeCo / TbFeCo. These thin films are formed by sputtering or vacuum evaporation.

Information is formed on the track in the form of marks (conceptually equivalent to pits). The tracks are formed concentrically or spirally when viewed from the direction perpendicular to the disk plane. Groove for tracking between two adjacent tracks and for separation.
e) is present. Conversely, a land (lan) is provided between the grooves.
d). In reality, the land and groove are reversed on the front and back of the disc. Therefore, when viewed from the direction in which the beam is incident (the direction perpendicular to the disk parallel), the front side is called a land and the back side is called a groove. Since the recording layer is formed over both the groove and the land, the groove portion may be a track or the land portion may be a track. There is no size relationship between the width of the groove and the width of the land. The groove has a width of 1.2, for example.
μm × depth 0.03 to 0.15 μm, spacing 0.4 μm, which are minute. In order to construct such land and groove,
Generally, a substrate has a land formed in a concentric or spiral shape on the surface and a groove sandwiched between two adjacent lands. A thin recording layer is formed on such a substrate. As a result, the recording layer has lands and grooves.

The latter type has no pit in principle. However, the optical disk may have track numbers, sector numbers, and other information in the form of pits. This pit is called a prepit. The prepits are preferably formed on the substrate. Then, when the recording layer is formed on the substrate, the recording layer has prepits. The prepit may be on the track or between the tracks. Therefore, in a recordable type optical disc, the substrate has grooves (or lands) and optionally prepits. This is also called an “optical disk substrate”.

However, both the read-only type and the recordable type optical disk substrates have minute and high-density concavo-convex patterns of pits, grooves, or prepits. Accurately forming such a concavo-convex pattern on a substrate is very time-consuming. Generally, the formation of the concavo-convex pattern is performed by using plastic as the material of the substrate and transferring it from a mold. Actually, for reproduction-only optical discs, "optical disc substrates" are mass-produced by an injection molding method using a mold. However, the pit is expected to become smaller in the future. This is because the optical disc is required to have a higher density. If the pits become smaller, mass production of the "optical disk substrate" by the injection molding method becomes difficult. The reason for this is that if the pits become smaller, the accuracy of transferring the uneven pattern from the mold deteriorates,
This is because the accurate pits will not be formed. Therefore, the following "2P substrate" is now proposed.

In a recordable type "optical disk substrate", requirements for the substrate (for example, heat resistance, strength, flatness, etc.) are more severe. Therefore, glass is used as the material of the substrate. Glass cannot be injection molded. Therefore, the "2P substrate" was developed. Radiation curable resin (Photo pol) on the mold (stamper)
The glass plate on the disk is pressed against the resin solution, and then the resin solution is cured by irradiation with radiation. Radiation means, for example, infrared rays, visible light, ultraviolet rays,
It refers to active energy rays such as X-rays, α rays, β rays, γ rays, and electron rays. The cured resin adheres to the glass disc, so the cured resin is peeled from the mold together with the glass disc. Then,
A composite consisting of a glass disk and a cured resin layer having an uneven pattern on the surface is obtained. This complex P hoto p
It is called "2P substrate" after the polymer. Therefore, in the present specification, the “optical disk substrate” configured by such a composite is referred to as “optical disk 2P substrate”.

The conventional apparatus for manufacturing a 2P substrate for an optical disc is mainly composed of a stamper, a pressing plate of a glass disk facing the stamper, a driving mechanism for pressing the pressing plate and the stamper against each other, and a power source of the driving mechanism. It consists of a motor. In general, the stamper is located at the bottom and faces upward. The resin liquid is discharged from the resin liquid discharging device onto the stamper in a donut shape. The pressing plate holding the glass disk on the lower surface approaches the stamper from above. Eventually, the glass disk comes into contact with the resin liquid and still descends. Therefore, the resin liquid is spread in the outer diameter direction and the inner diameter direction. Eventually, the tip of the resin liquid reaches a predetermined position in the outer diameter direction and the inner diameter direction. Here, the descent of the glass disk is stopped. As a result, the resin layer has a predetermined thickness. On the contrary, the discharge amount of the resin liquid is determined in consideration of the predetermined thickness. Centering is performed in this state. Centering will be described below.

As mentioned above, the tracks are concentric or spiral. The latter case can be regarded as a circle. Therefore,
The center of both circles is called the "center of the track circle" here. By the way, the "center of the track circle" must coincide with the center of rotation of the optical disc. The non-coincidence is called eccentricity, and the degree thereof is called the first eccentricity amount here. When the first amount of eccentricity is large, tracking becomes impossible. The reproducing or recording apparatus has a tracking servo system for driving the optical head along the track. However, when the first eccentricity amount is large, the track position (position in the radial direction of the disk) fluctuates rapidly beyond the control range of the servo system.

In order to make the "center of the track circle" coincide with the center of rotation of the optical disk, a taper member 36 having an inverted conical head is used as shown in FIG. The taper member 36 is lowered through the center hole of the glass disk 34, the center hole of the stamper 31 and the center hole of the backing member 33. The backing member 33 is arranged on a horizontally installed base 39. Then, the inclined surface 36a of the head of the taper member 36 comes into contact with the central hole (inner diameter) of the glass disk 34, and the taper member 36
And the glass disk 34 moves horizontally,
As a result, the center of the hole of the glass disk 34 coincides with the stamper 31. Since the center of the stamper 31 is made in advance so as to coincide with the "center of the track circle", the center of the glass disk 34 coincides with the "center of the track circle". Therefore, if you bring the center of rotation to the center of the glass disk 34,
The first amount of eccentricity disappears. Strictly speaking, it is expressed that the first eccentricity amount becomes small.

In practice, after finishing the optical disc, when the center hub is attached to the center hole of the glass disc (optical disc), the center hub is attached while observing the "center of the track circle" with a microscope. What is a center hub?
It is a type of coupler (coupling means) that connects a rotating shaft on the reproducing or recording device side to an optical disk and transmits the rotation of the rotating shaft to the optical disk. The first eccentric amount becomes smaller by mounting the center hub in this way.

[0012]

There is a demand for increasing the speed of reproduction or recording. Therefore, the optical disc must be rotated at a higher speed. However, it has been found that when the current optical disc is rotated at a higher speed, tracking becomes impossible.

[0013]

The inventors of the present invention have made earnest studies and found that the cause of the problem is that the center of gravity of the optical disk and the center of rotation do not coincide with each other.
The disagreement is also called eccentricity, and the degree thereof is called the second eccentricity here. If the second eccentricity is large, the rotating shaft receives a force that causes a "gripping" motion. If the bearing continues to rotate for a long time, the bearing will be excessively worn. As a result, the rotating optical disk undergoes a "gripping" motion, which makes the optical disk largely touching up and down, making focusing impossible. The ten points of the optical disc are almost at the center of the outer circle of the optical disc. As a result of examination by the present inventor, the 2P substrate of the conventional optical disc had the second eccentricity of 25 μm or more. This is the center of the circle of the center hole (inner diameter) of the glass disk,
It is considered that the cause is that the center of the outer circle is generally displaced by about 25 μm.

As a result of further research, the present inventor found that 2P
It was found that the second eccentricity decreases when the centering at the time of manufacturing the substrate is performed based on the outer diameter of the glass disk,
The present invention has been accomplished.

Therefore, the present invention firstly comprises a stamper, a pressing plate of a glass disk facing the stamper, a drive mechanism for pressing the pressing plate and the stamper against each other, and a motor as a power source of the drive mechanism. 2P for optical disc
Apparatus for manufacturing a substrate, each predetermined distance L _1, L _2, L ₃ ...... (where L from "the center of the track circle" of the stamper to the peripheral portion of the stamper may be different and equal but, Two or more (preferably three or more) so that the radius is always larger than the radius r of the glass disk.
In particular, an apparatus is provided which is provided with four reference members, which are preferably arranged on orthogonal cross lines.

The present invention secondly provides an apparatus according to the first invention, wherein the predetermined distance L is equal for all the reference members.

Further, the present invention thirdly provides predetermined distances L ₁ and L from the "center of the track circle" of the stamper, respectively.
₂ , L ₃ ... (where L is larger than the radius r of the glass disk), two or more (preferably three or more).
In particular, there is provided a stamper characterized by being provided with four reference members, which are preferably arranged on orthogonal cross lines.

A fourth aspect of the present invention provides the stamper according to the third aspect, wherein the predetermined distance L is the same for all the reference members.

The 2P substrate manufactured according to the present invention has a second
The amount of eccentricity is 10μ or less, which is the first novel thing in the world. Therefore, a fifth aspect of the present invention is to provide a 2P substrate for an optical disk, which comprises a glass disc and a resin molded body layer formed thereon, and a "track circle center" molded on the molded body and an outer peripheral circle of the substrate. Provided is a 2P substrate whose eccentricity with respect to the center (second eccentricity) is 10 μm or less.

In the present invention, the three or more reference members provided on the peripheral portion of the stamper are located at a predetermined distance L (where L is larger than the radius r of the substrate) from the "center of the track circle" of the stamper. Is located in. Therefore, after pressing the glass disk against the stamper via the resin liquid,
By setting the distance between the outer circumference of the glass disk and each reference member to be a known predetermined distance, the center of the track circle can be aligned with the center of the outer circumference of the glass disk. Furthermore, since the center of the track circle and the center of rotation of the disc can be made to coincide with each other by a center hub that will be attached later,
The center of the outer circumference of the 2P substrate (glass disk) and the center of rotation can be matched. By the way, since the center of gravity is substantially coincident with the center of the outer circumferential circle of the 2P substrate, the center of gravity of the disk is coincident with the center of rotation. Therefore, according to the manufacturing apparatus of the present invention, it is possible to obtain a 2P substrate having an eccentricity of 10 μm or less and an extremely small imbalance. The "peripheral portion of the stamper" on which the reference member is installed means both the peripheral portion on the stamper and the peripheral portion outside the stamper.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a side view showing the configuration of a stamper included in the optical disk 2P substrate manufacturing apparatus according to this embodiment, FIG. 1B is a plan view of the stamper, and FIG. It is an enlarged view which shows the structure of a principal part. In the apparatus according to the present embodiment, the stamper is installed on the backing member fixed on the base, and as shown in FIG. 1, the stamper is equidistant from the center 0 of the track circle 1a of the stamper.
_{At the position of 1} (however, L ₁ is larger than the radius r of the substrate),
Four reference members 2 are provided at positions rotated by 90 ° with respect to the “center of the track circle”. Further, as shown in FIG. 2, on the base 29 around the stamper, the 4
Four digital micrometers 26 (only one is shown in the figure) corresponding to each of the reference members are installed via fixing members 28.

The centering process by this apparatus will be described with reference to FIG. 2. First, the tip of the probe 27 provided in the digital micrometer 26 is brought into contact with the end surface 22a of the reference member to read each meter. Is reset to 0. Next, after the resin liquid 25 is spread between the glass disk 24 and the stamper 21, the probe 27 of the digital micrometer is extended toward the glass disk 24, and its tip is brought into contact with the outer peripheral edge of the glass disk 24. , The glass disk 24 so that the readings of the two sets of facing micrometer are equal.
Move horizontally and fix. That is, by this operation, the center of the outer circumferential circle of the glass disk and the "center of the track circle" (the midpoint of the two reference members at the opposing positions) coincide with each other in the two axial directions orthogonal to each other. Then, the resin liquid 25 is cured by irradiating with ultraviolet rays, and the cured resin and the stamper 21 are separated from each other to obtain a 2P substrate.

Next, a second embodiment in which the operation of the first embodiment is automated will be described. FIG. 4 is a schematic layout view of the present automation device as viewed from above, and FIG. 5 is a vertical cross-sectional view of one of the unit parts automated in this embodiment. The configuration of this automated device will be described. The backing member 53 is installed on the base 59, and the stamper 51 is arranged in the central portion on the backing member 53. In the periphery of the track of the stamper 51, reference members 52 of the same shape and the same size are provided at the same distance L ₁ (where L ₁ is larger than the radius r of the substrate) from the “center of the track circle”, and the “track” of the stamper is provided. Four of them are installed at positions rotated by 90 ° with respect to the "center of the circle". In each reference member, A in FIG. 5 is equal.

As shown in FIG. 4, on the base 59 at the periphery of the stamper, the four members corresponding to the reference members 52 are provided.
A glass disk positioning device unit (only one is shown in FIG. 5) equipped with individual automation devices is installed.
The glass disc positioning device has a rod 8 for pushing the glass disc 54 on the stamper 51 along the position of the respective reference member 52. The shape of the rod 8 is a stepped shape with a thin tip region. The narrowed portion penetrates the hole of the reference member 52, and the tip of the rod 8 can come into contact with the tip of the outer periphery of the glass disk 54. The length of this narrowed portion (B in FIG. 5) is the same for each rod. The rod 8 is a glass disc 54
The linear bearing 13 is supported so that it can move in a direction in which it can come into contact with the outer peripheral edge (or in the opposite direction). One end of the rod 8 is in contact with a touch sensor 14 for detecting a point where the tip of the rod 8 comes into contact with the outer peripheral end of the glass disk and the rod 8 cannot move.
Further, one end thereof is formed with a convex portion so as to come into contact with a member 19 for moving the rod 8 in a direction opposite to the glass disk 54. Both the member 19 and the touch sensor 14 are fixed by the same member 20, which is the base 59.
The linear guide 15 is arranged so that it can move upward in the direction toward the glass disk and in the opposite direction. Further, the member 20 has a feed screw 16 for moving the member 20 in the direction described above.
And the feed screw 16 is attached to a coupling 18 for transmitting power installed in a stepping motor 17 for rotating and driving the feed screw 16. The automated 2P substrate manufacturing apparatus according to this embodiment has the above-described configuration.

Next, a method for manufacturing a 2P substrate using this apparatus will be described. (1) Setting Unit Origin The stepping motor 17 is driven and the feed screw 16 is rotated to move the member 20. When pressed by the touch sensor 14 installed on the member 20, the rod 8 moves in the direction toward the outer peripheral edge of the glass disk. As the rod 8 advances in the direction of the glass disk, the thinner portion penetrates the hole of the reference member 52, and the end face 12 of the thicker portion contacts the reference member 52. The touch sensor 14 senses this point in time and generates a load detection signal, which stops the stepping motor 17. This operation is performed in each unit.

Reference member 5 arranged around the stamper 51
No. 2 is attached to the stamper 51 at the same distance from the center of the track, and the length of the narrowed portion of the rod 8 (B in FIG. 5) is the same for each rod, so the stepping motor 17 is stopped. The tip of each rod 8 at the time point is equidistant from the "center 0 of the track circle" of the stamper 51. This position is the origin. When the origin is set, the stepping motor 17 is driven in each unit and the feed screw 16 is rotated to bring the member 19 into contact with the convex portion of the rod 8 and retract the rod 8. Retreat the same distance for each unit. This retracted position is the starting point of the position setting operation of the glass disk.

(2) Position setting of glass disk After setting each unit by (1), stamper 51
The resin liquid 55 is applied onto the above. The glass disc 54 is placed on the resin liquid and pushed downward, and the resin liquid 55 is spread until it reaches the vicinity of the outer periphery of the glass disc 54. Once set up to this point, the stepping motor 17 is driven so as to rotate each feed screw 16 at the same speed, and by moving the member 20, one end of the rod 8 is pushed by the tip of the touch sensor 14,
The rod 8 is moved toward the outer peripheral edge of the glass disk 54. This operation is performed simultaneously for all four units.

At the time when the resin liquid has been spread, the "center of the track circle" of the stamper 51 and the center of the outer diameter circle of the glass disk 54 do not coincide with each other, and there is a deviation. Therefore, when the four rods 8 are simultaneously moved toward the glass disk 54 at the same speed as described above, the time when the tip of the rod 8 contacts the outer peripheral edge of the glass disk 54 is deviated.
That is, to describe two units that are symmetrical with respect to the "center of the track circle" of the stamper 51, the tip of one rod 8 is the glass disc 5
4, but the tip of the other rod does not reach the outer peripheral edge of the glass disk 54.
Therefore, the rod 8 in contact with the outer peripheral edge of the glass disc 54 pushes the glass disc 54. The other rod, which is not in contact with the outer peripheral edge, also continues to move toward the outer peripheral edge of the glass disk 54, and eventually comes into contact with it. When both rods touch the outer edge of the glass disc 54, the glass disc 54 can no longer be pushed. Touch this point to touch sensor 14
Senses and stops the stepping motor 17. These operations are performed by each unit.

The position where the glass disk 54 is stopped means that the outer peripheral edge of the glass disk 54 is at a position equidistant from each reference member 52. In other words, the "center of the track circle" of the stamper 51 and the center of the outer circumference of the glass disk (2P substrate) coincide with each other, and the optical disc manufactured from this 2P substrate has the "center of the track circle" by attaching the center hub. "And the center of rotation match. Then, the center of the outer circumference of the optical disc (2P substrate) (corresponding to the center of gravity) coincides with the center of rotation. Then, the resin liquid 5 is cured by irradiating with ultraviolet rays, and the cured resin and the stamper 21 are separated from each other to obtain a 2P substrate.

[0030]

As described above, according to the present invention,
Since three or more reference members are provided around the stamper,
High quality 2P with a very small second eccentricity of 10 μm or less
The substrate is manufactured.

[Brief description of drawings]

FIG. 1A is a side view showing a configuration of a stamper according to an embodiment of the present invention, and FIG. 1B is a plan view of the stamper.

FIG. 2 is an enlarged side view showing a configuration of a main part of a manufacturing apparatus for a 2P substrate for an optical disc according to an embodiment of the present invention.

FIG. 3 is a conceptual diagram showing a principle of a centering process in a conventional optical disk 2P substrate manufacturing apparatus.

FIG. 4 is a schematic layout view of an automation device according to a second embodiment in which the operation in the first embodiment is automated, as viewed from above.

FIG. 5 is a vertical cross-sectional view of one of the unit parts automated in the second embodiment.

[Explanation of symbols]

 1,2,31,41,51 Stamper 1a Track 2,22,42,52 Reference member 22a Reference member end face 3,23,33,53 Backing member 24,34,54 Glass disk 25,35,55 Resin liquid 26 Digital Micrometer 27 Measuring Element 28 Fixing Member 29, 39, 49, 59 Base 36 Tapering Member 36a Tapered Member Head Slope O “Center of Track Circle” 8 Rod 13 Linear Bearing 14 Touch Sensor 15 Linear Guide 16 Feed Screw 17 Stepping motor 18 Coupling 19 Rod moving member 20 Touch sensor fixing member In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (5)

[Claims] 1. An apparatus for manufacturing a 2P substrate for an optical disk, which comprises a stamper, a pressing plate of a glass disk facing the stamper, a driving mechanism for pressing the pressing plate and the stamper against each other, and a motor which is a power source of the driving mechanism. In the peripheral part of the stamper, predetermined distances L ₁ , L ₂ , L ₃ from the “center of the track circle” of the stamper, respectively.
(However, L may be the same or different, but it must be larger than the radius r of the glass disk.) 2 or more (preferably 3 or more. Particularly preferably arranged on the orthogonal cross line) 4) provided with reference members. 2. The device according to claim 1, wherein the predetermined distance L
Is equal for all reference members. 3. The center of the track circle of the stamper
From the respective predetermined distances L ₁ , L ₂ , L ₃ (where L is
Is set to be larger than the radius r of the glass disk), and two or more (preferably three or more, particularly preferably four arranged on the orthogonal cross lines) reference members are provided. Stamper to do. 4. The stamper according to claim 3, wherein the predetermined distance L is the same for all the reference members. 5. A 2P substrate for an optical disk comprising a glass disc and a resin molded body layer formed thereon, wherein a "track circle center" molded on the molded body and a peripheral circle center of the substrate. A 2P substrate having an eccentricity amount (second eccentricity amount) of 10 μm or less.