JPH05174431A - Device for producing 2p substrate for optical disk and 2p substrate produced by the device - Google Patents

Abstract

PURPOSE:To provide a producing device which can produce a high quality 2P substrate for an optical disk with an extremely low bit rate and with high efficiency and high stability. CONSTITUTION:The device for producing a 2P substrate for an optical disk is conventionally provided with a stamper 2, a pressing plate 5 for a glass disk opposite to the stamper 2, a drive mechanism which presses the stamper 2 and the plate 5 with each other, and a motor serving as a power source of the drive mechanism. The motor uses a stepping motor, for example, which is capable of the low speed control. In such a constitution, the dent defect of a resin molded body layer is reduced down to 10<7> or less in terms of a bit error rate for the 2P substrate consisting of a glass disk and the resin-molded body layer formed on the glass disk.

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 composed of a magnetic thin film that can be perpendicularly magnetized, and once the direction of magnetization is aligned upward or downward (called initialization), a laser beam is irradiated onto this and the recording magnetic field is simultaneously generated. 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. As a typical magneto-optical recording layer,
Rare earth-transition metal amorphous alloy, eg TbF
e, TbFeCo, GdFe, GdCo, DyFe, G
Single layer film such as dTbFe, GdTbCo or GdFe / T
There are two-layer films such as bFe 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 (perpendicular to the disk plane), 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”.

2 and 3 show a schematic structure of a conventional apparatus for manufacturing a 2P substrate for an optical disk. First, as shown in FIG. 2, a manufacturing apparatus of this type of optical disk 2P substrate includes a backing member 23 and a stamper 22 mounted on a base (not shown) so as to face the stamper 22. A pressing plate 25 that holds the glass disk 21 is provided, and the pressing plate 25 is configured to be vertically movable by the air cylinder 20.

The manufacturing of the 2P substrate for an optical disc by the apparatus is performed as follows. That is, the resin liquid 24 is discharged onto the stamper 22, the glass disk 21 attached to the pressing plate 25 is lowered by the air cylinder 20, and the glass disk 21 is stamped via the resin liquid 24 discharged onto the stamper. Stamper 22 by pressing on 22
The resin liquid 24 is spread between the glass disk 21 and the glass disk 21. Then, when the resin liquid 24 is spread to a predetermined position in the radial direction of the glass disc 21, the pressing of the glass disc 21 is stopped, and the spread resin liquid is irradiated with a radioactive energy ray to spread the resin liquid. A 2P substrate for an optical disc is manufactured by curing and forming a resin molded body layer on the glass disk, and then separating the stamper 22 and the cured resin (resin molded body layer).

Further, FIG. 3 is a schematic view showing the configuration of another conventional 2P substrate manufacturing apparatus for optical discs.
After the glass plate 31 is held in close proximity to the stamper 32 by the pressing plate 35 in advance, the resin liquid 34 is pressure-discharged from the resin liquid discharge port provided in the central part of the stamper 32 to press the glass disc 31 and the stamper 32 together. The resin liquid is spread in the gap.

[0011]

By the way, an optical disc is manufactured from a 2P substrate for an optical disc, and after recording reference information in the case of a recordable type (in the read-only type, the stamper is provided with the reference information. ), When the information is reproduced from the optical disc, not all the pits or marks may be reproduced. Rather, it doesn't actually play. At this time, the ratio of “the number of unreproduced pits or marks” to “the number of all recorded pits or marks” is called the bit error rate (BER). There are many causes of BER, and it is not easy to find the cause. The BER of the conventional optical disk is about 10 ⁻⁵ to 10 ⁻⁴ . However, in the future, when the optical disc is used as an external memory of a large computer or a memory for image processing (especially high-definition), this level of BER cannot be accepted. An object of the present invention is to further reduce BER.

[0012]

As a result of earnest research, the present inventor has found that one of the causes of BER is a 2P substrate (in particular, a dent defect in a molded body layer). The uneven pattern from the stamper was not correctly transferred to the molded body layer. That is, there were no depressions (pits or grooves) in the originally required positions, or depressions (pits or grooves) existed in unnecessary positions in the molded body layer. This pit is called a "pit defect". Many dent defects pushed up BER. Furthermore, as a result of further research, it was found that the cause of the dent defect was in the manufacturing apparatus for the 2P substrate. Therefore, as a result of efforts to improve this device, the present invention has been accomplished.

Accordingly, the present invention comprises, firstly, 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 which is a power source of the drive mechanism. 2P for optical disc
In the substrate manufacturing apparatus, there is provided an apparatus for manufacturing an optical disk 2P substrate, wherein the motor is a motor capable of low speed control.

A second aspect of the present invention is the control means according to the first aspect, which controls the pressing speed and the pressing degree on the basis of predetermined data when the pressing plate and the stamper are pressed against each other. An apparatus for manufacturing a 2P substrate for an optical disc, which is characterized by being provided.

A third aspect of the present invention is, in the first or second aspect, when the pressing plate and the stamper are pressed against each other, a glass disk attached to the pressing plate and the stamper facing the glass disk. An apparatus for manufacturing a 2P substrate for an optical disc is provided, which is provided with a parallel adjusting means for adjusting the parallelism of the.

The 2P substrate manufactured by the apparatus of the present invention has a dent defect of the molded body layer of 10 ⁻⁷ when expressed by BER.
It is extremely low as below, and such a 2P substrate is the first novel thing in the world. Therefore, a fourth aspect of the present invention is, in a 2P substrate for an optical disc comprising a glass disk and a resin molded body layer formed thereon, the pit defect of the molded body layer is expressed by a bit error rate of 10 ^−7. Provided is a 2P substrate characterized by the following.

[0017]

The exact reason why the device of the present invention can reduce the pit defect is not clear. Conventional figure 2
In this device, bubbles are generated in the resin liquid when the glass disk is pressed against the resin liquid. These bubbles may be the cause of the pit defects. As a result of earnest studies by the present inventor, in the apparatus of FIG. 2, the speed at which the glass disk-forming resin liquid comes into contact affects the “air bubble entrapment amount”, which is extremely low (5 μm /
It was found that it is important to be about (sec). The device of the present invention has a low speed controllable motor (for example, a stepping motor). Therefore, extremely low speed control is possible, and the same speed can be repeated with high reproducibility. Therefore, it is presumed that a 2P substrate with few dent defects can be manufactured with a high yield. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0018]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an embodiment of the present invention. As shown in the figure, in the apparatus for manufacturing an optical disk 2P substrate according to this embodiment, the stamper 2 is installed on a base (not shown) via the backing member 3. On the other hand, a pressing plate 5 capable of sucking and holding the glass disk 1 is provided above the stamper 2, and the pressing plate can be moved up and down by a stepping motor 7 attached to a fixing member 11. That is, when the feed screw 8 is rotated by the stepping motor 7 via the coupling 9, the pressing plate 5 moves up and down along the guide rail 10. Further, the pressing plate 5 is provided with a parallelism adjusting mechanism 6 for adjusting the parallelism of the facing surfaces of the stamper 2 and the glass disk 1, and the glass disk 1 held by the pressing plate and the glass disk 1 are opposed thereto. By adjusting the parallelism with the stamper 2, it is possible to form a resin molded body layer having a uniform thickness on the glass disk 1.

The production of a 2P substrate for an optical disc by this apparatus is carried out as follows. That is, the glass disk 1 is adsorbed and held by the pressing plate 5, and the stamper 2 is held.
The resin liquid 4 is discharged upward, and the feed screw 8 is rotated by the stepping motor 7 to move the pressing plate 5 downward along the guide rail 10. Then, the glass disk 1 held by the pressing plate is pressed against the stamper 2 with the resin liquid 4 discharged on the stamper interposed therebetween, thereby spreading the resin liquid 4 between the stamper 2 and the glass disk 1. Here, the pressing of the glass disk 1 against the stamper 2 is performed by the stepping motor 7 at extremely low speed and with high accuracy.

Then, the resin liquid 4 is applied to a predetermined position on the glass disk.
The pressing of the glass disc 1 is stopped at the time when the glass disc 1 is spread, and the spread resin liquid is cured by irradiating with active energy rays such as ultraviolet rays and radiation to cure the spread resin liquid on the glass disc 1. Is formed, and then the stamper 2 and the cured resin (resin molded body layer) are separated from each other to complete the production of the 2P substrate.

The motor for moving up and down the pressing plate (glass disk) is not limited to the stepping motor as in the present embodiment, but other motors can be used as long as they can operate at low speed and with high accuracy. For example, an AC servo motor or the like can be used. Further, in this embodiment,
Although the glass disc 1 is lowered toward the stamper 2 from which the resin liquid is discharged, the glass disc 1 is fixed to any one of them, and the stamper 2 is moved upward toward the fixed glass disc. It is also possible to adopt a configuration that allows it. It is also possible to arrange the stamper 2 on the upper side and the pressing plate 5 (glass disc 1) on the lower side.

[0022]

According to the present invention, by using a motor capable of controlling a low speed, it is possible to stably manufacture a high quality 2P substrate for an optical disc with a significantly reduced BER with good reproducibility.

Further, according to the third aspect of the invention, when the glass disc and the stamper are pressed against each other, the parallelism adjusting means provided on the pressing plate causes the parallelism of the opposing surfaces of the stamper and the glass disc. BER by adjusting
It is possible to manufacture a high-quality 2P substrate for an optical disc in which the resin molding layer is low and the thickness of the resin molding layer is uniform.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a manufacturing apparatus for a 2P substrate for an optical disc according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the configuration of a conventional apparatus for manufacturing a 2P substrate for an optical disc.

FIG. 3 is a schematic diagram showing a configuration of another conventional manufacturing apparatus for another optical disk 2P substrate.

[Explanation of symbols]

1,21,31 Glass disk 2,22,32 Stamper 3,23,33 Backing member 4,24,34 Resin liquid 5,25,35 Pressing plate 6 Parallelism adjusting mechanism 7 Stepping motor (low speed controllable motor Example) 8 Feed screw 9 Coupling 10 Guide rail 11 Fixing member 20 Air cylinder

Claims (4)

[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. 2. The apparatus for manufacturing a 2P substrate for an optical disc, wherein the motor is a low speed controllable motor. 2. The control means for controlling the pressing speed and the pressing degree on the basis of predetermined data when the pressing plate and the stamper are pressed against each other. 2P for optical disc
Substrate manufacturing equipment. 3. When the pressing plate and the stamper are pressed against each other, parallel adjustment means is provided for adjusting the parallelism between the glass disk attached to the pressing plate and the stamper facing it. An apparatus for manufacturing a 2P substrate for an optical disc according to claim 1 or 2. 4. A 2P substrate for an optical disc comprising a glass disk and a resin molding layer formed on the glass disk, wherein a dent defect in the molding layer is expressed by a bit error rate of 1
2P substrate characterized by being 0 ^-7 or less.