JP2005011411A - Method for manufacturing flexible optical disk substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a flexible optical disk which prevents ripples on a disk surface, has good roundness and recording and reproducing characteristics of high quality by imparting tension in a radial direction to a flexible optical disk at the time of depositing a recording film etc., thereby preventing the random deformation and warpage due to the deposition stresses. <P>SOLUTION: The recording film etc., are deposited on the flexible optical disk transferred with a pre-format pattern from a stamper while a tension is imparted thereto in the radial direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial application fields]
The present invention relates to an optical recording medium such as an optical disc, and more particularly to a flexible optical disc that is a high recording density optical disc and a method for manufacturing the same.
[0002]
[Prior art]
Optical disks are widely used as CDs, DVDs and the like because they are removable and have a large capacity. In these methods, a recording film is usually formed on a polycarbonate substrate having a thickness of 1.2 or 0.6 mm, and signals are recorded and reproduced. In this recording / reproduction, mechanical position accuracy is required to collect the light on the recording surface, but the substrate is flattened to give rigidity, and the optical pickup is servoed to increase the position accuracy. ing.
[0003]
Currently, in order to further increase the recording capacity, developments are being made to further reduce the diameter of the light spot by increasing the numerical aperture (NA) of the objective lens or shortening the wavelength of the laser. To increase the numerical aperture (NA), it is necessary to reduce the tilt (surface runout) of the substrate, but to improve the accuracy of the manufacturing substrate, to mount a tilt (surface runout) servo on the pickup, and to record A tilt (surface shake) margin is increased by providing a thin cover layer of about 0.1 mm on the film and recording / reproducing data from the cover layer side.
[0004]
Although it is possible to reduce the tilt (surface runout) of the substrate by devising the material and the manufacturing method, the cost increases. It is also expensive to mount a tilt (surface shake) servo on the optical pickup.
Furthermore, there is a method of reproducing from the recording film side without passing through the substrate, but the distance between the recording film surface and the objective lens can be secured only about 0.1 mm. For this reason, in order to rotate a normal optical disk that is a rigid body and prevent collision with the objective lens, it may be possible to improve the chucking accuracy of the disk in order to reduce surface deflection, but these all increase the cost. Connected.
[0005]
Therefore, the optical disk itself is not a rigid body, and the mechanical accuracy is not improved, but the optical disk is manufactured from a flexible material, and a guide is provided on the side opposite to the recording / reproducing surface of the optical disk. With this configuration, when the optical disc is rotated, the optical disc is aerodynamically levitated (Bernoulli levitating; non-contact) and stabilized by the guide facing the objective lens with the optical disc interposed therebetween, and the tilt is limited. It becomes possible to approach 0 without any change.
[0006]
As a conventional manufacturing method for producing these flexible optical disk substrates, a thermoplastic sheet or a thermosetting resin is applied to the sheet surface while a flexible sheet such as a PET film is conveyed by a roll-to-roll method, and a fine stamper is formed. There is a method in which a concavo-convex pattern is transferred and a recording film is formed after thermosetting (see Japanese Patent Application Laid-Open No. 6-60423).
[0007]
[Problems of the prior art]
In this conventional roll-to-roll system, tension can be applied positively in the winding direction, but for example, it is difficult to apply tension in the direction orthogonal to the winding direction. If it is a square size such as a display element, it can be sufficiently handled by this method, but in the case of a flexible optical disc, the guide groove of the pickup, the ID pit row indicating the address information, etc. are formed in a spiral shape, In the DVD disc standard, it is necessary to make the circularity of the guide groove about 40 μm. In this method, it is difficult to satisfy this specification, the roundness of the manufactured disc is 50 μm or more, the pickup tracking is poor, and high quality recording / reproducing characteristics cannot be obtained.
[0008]
[Patent Document 1] Japanese Patent Laid-Open No. 6-60423
[Problems to be solved by the invention]
The present invention provides a recording film or the like by applying a tension force in the radial direction to the flexible optical disk substrate when forming a recording film or the like to prevent random deformation or warping caused by the film forming stress. In other words, a flexible optical disk having good circularity and high-quality recording / reproducing characteristics is produced without causing ripples on the disk surface after film formation.
[0010]
[Means for Solving the Problems]
[Solution] (Corresponding to claim 1)
The means taken in order to solve the above problem is to form a recording film or the like on the flexible optical disk substrate on which the preformat pattern is transferred from the stamper, while applying tension in the radial direction.
[0011]
[Action]
Since a recording film or the like is formed on the flexible optical disk substrate while applying a tensile force evenly in the radial direction, it is possible to prevent random deformation and warpage caused by the film formation stress, and there is no generation of ripples. The roundness of the preformat pattern is also good.
[0012]
Embodiment 1 (corresponding to claim 2)
Embodiment 1 is to form a recording film or the like while applying tension in the radial direction at a radial position larger than the final disk size in the above solution.
[0013]
Embodiment 2 (corresponding to claim 3)
Embodiment 2 is to form a recording film or the like while applying tension in the radial direction at a radial position larger than the final disk size using two rings having different diameters in the above solution. .
[Action]
By applying tension using two rings having different diameters, the tension can be made uniform in the radial direction. Further, when the recording film is a phase change film, it can be applied to the initialization process in a state where it is set in two rings, so that it is locally applied to the film due to the stress of the recording film or heat during film formation. Since the distortion does not occur, the recording film can be surely crystallized.
[0014]
Embodiment 3 (corresponding to claim 4)
Embodiment 3 is the same as Embodiment 2 described above, except that the clearance between the inner diameter of the large-diameter ring and the outer diameter of the small-diameter ring is 1.5 to 3.2 of the thickness of the flexible optical disc substrate to be sandwiched. It is to be double.
[Action]
Since the clearance between the inner diameter of the large-diameter ring and the outer diameter of the small-diameter ring is 1.5 to 3.2 times the thickness of the sandwiched flexible optical disk substrate, a sufficient tension can be given in the radial direction. A smooth flexible optical disk substrate is obtained. If the clearance is less than 1.5 times the thickness of the flexible optical disk substrate, the clearance of the two rings is insufficient with respect to the thickness of the flexible optical disk substrate, making it impossible to sandwich the flexible optical disk substrate successfully. If it is larger than 3.2 times, the clearance of the two rings is too large with respect to the thickness of the flexible optical disk substrate, causing the flexible optical disk substrate to slip, giving sufficient tension in the radial direction. I can't.
[0015]
Embodiment 4 (corresponding to claim 5)
Embodiment 4 is that, in Embodiment 2 or 3, the knurling is carved on the upper surface of the small-diameter ring among the two rings having different diameters.
[Action]
Of the two rings with different diameters, the knurling is engraved on the upper surface of the small-diameter ring. It is possible to provide a sufficient grip force evenly in the radial direction by firmly gripping the surface.
[0016]
Embodiment 5 (corresponding to claim 6)
Embodiment 5 is that, in Embodiments 2 to 4, knurls are engraved on the inner surface of the large-diameter ring among the two rings having different diameters.
[Action]
By knurling the inner surface of the large-diameter ring, a stronger tension can be applied.
[0017]
Embodiment 6 (corresponding to claim 7)
Embodiment 6 is that the knurled carved in two rings having different diameters in the above embodiment 4 or 5 is a twill knurled.
[Action]
Since the engraved knurl pattern is the Ayame knurl, the tension can be applied very effectively.
[0018]
[Embodiment 7] (Corresponding to Claim 8)
In Embodiment 7, the heights of the two rings having different diameters in Embodiments 2 to 6 are higher in the large-diameter ring than in the small-diameter ring, and the difference in height is larger than the thickness of the flexible optical disk substrate to be sandwiched. Is also big.
[Action]
By specifying the height of two rings having different diameters, even when the target is close to the surface of the flexible optical disk substrate in the film forming process of the recording film or the like, the large-diameter ring is physically larger than the surface of the flexible optical disk substrate. By approaching the target, it is possible to avoid contact and improve the yield in the film formation process.
[0019]
[Embodiment 8] (Corresponding to Claim 9)
Embodiment 8 is that, in Embodiments 2 to 7, the electrical specific resistance of two rings having different diameters is 100 μΩ · cm or less.
[Action]
By specifying the electrical specific resistance of the two rings having different diameters, sufficient electrical conduction can be obtained and the deposition efficiency can be improved, so that the deposition process can be performed at a higher cycle. Further, since the ring is difficult to be charged, the adhesion of contaminants (contaminants) can be prevented.
[0020]
Embodiment
The present invention provides a uniform tension to the flexible optical disk substrate in the radial direction against the heat and film stress generated in the film formation process of the flexible optical disk. This makes it possible to manufacture a flexible optical disk with good quality. Hereinafter, embodiments will be described with reference to FIGS.
[0021]
[Example 1]
First, Example 1 will be described.
The flexible optical disk substrate 1 is obtained by transferring the preformat pattern formed on the stamper to one side of a polycarbonate resin having a thickness of 100 μm as a base film. The flexible optical disk substrate 1 is made of two rings having different diameters (SUS304; electrical specific resistance 72 μΩ · cm), that is, a large diameter, at a radial position larger than the disk size (final disk size) of the final flexible disk. A recording film (such as a recording film) is formed while being sandwiched between the ring 15 and the small-diameter ring 11 and imparting a tension force evenly in the radial direction (FIG. 4).
[0022]
When the flexible optical disk substrate 1 is sandwiched between the two rings having different diameters, first, the flexible optical disk substrate 1 is set on the small diameter ring 11 with the transfer surface 2 facing upward, and then the large diameter This can be done by fitting the ring 15 to the outside of the small diameter ring 11. In this way, the flexible optical disk substrate 1 can be uniformly tensioned in the radial direction by the two rings having different diameters. At this time, the clearance between the inner diameter of the large-diameter ring 15 and the outer diameter of the small-diameter ring 11 is 0.18 mm. The upper surface (one side surface) of the small-diameter ring 11 is engraved with a twill knurl 12 (FIG. 2), and the inner surface (inner peripheral surface) of the large-diameter ring 15 is similarly engraved with the twill knurl 16. (Figure 3). The height of each ring is higher by 0.15 mm for the large-diameter ring 15.
[0023]
After forming the recording film or the like, the inner and outer diameters are processed into a desired disk size with a press or the like, whereby the flexible optical disk 5 is completed. The roundness of the preformat pattern of the final product, the flexible optical disk, was 20 μm. The flexible optical disk 5 is mounted on the evaluation apparatus shown in FIG. 1 and rotated by the spindle 22, the guide 20 is brought close to the surface of the flexible optical disk to be stabilized by air floating, and then the recording / reproducing operation is performed. did. In this recording / reproducing operation, the focus servo can be easily locked, the tracking followability is good, and high-quality recording / reproducing characteristics are obtained. The objective lens 21 is one element that constitutes an optical pickup.
[0024]
[Example 2]
In Example 2, a flexible optical disk is manufactured in the same manner as in Example 1 above. However, in Example 2, a polyester resin having a thickness of 75 μm is used as the base film. The clearance between the inner diameter of the large diameter ring 15 and the outer diameter of the small diameter ring 11 is 0.22 mm. After forming the recording film or the like, the inner and outer diameters are processed into a desired disk size by a press or the like, and then the flexible optical disk 5 is completed. The roundness of the preformat pattern of the flexible optical disk as the final product was 18 μm.
The flexible optical disk 5 was mounted on the evaluation apparatus shown in FIG. 1, rotated by the spindle 22, the guide 20 was brought close to the surface and the surface runout was stabilized, and then the recording / reproducing operation was performed. As a result, similar to the first embodiment, high quality recording / reproducing characteristics were obtained.
[0025]
[Example 3]
Also in Example 3, a flexible optical disk is manufactured as in Example 1. However, in Example 3, a polycarbonate resin having a thickness of 120 μm is used as the base film. The clearance between the inner diameter of the large diameter ring 15 and the outer diameter of the small diameter ring 11 is 0.2 mm. After forming the recording film and the like, the flexible optical disk 5 is completed by processing the inner and outer diameters into a desired disk size with a press or the like. The roundness of the preformat pattern of the flexible optical disk as the final product was 25 μm.
The flexible optical disk 5 was mounted on the evaluation apparatus shown in FIG. 1, rotated by the spindle 22, the guide 20 was brought close to the surface and the surface runout was stabilized, and then the recording / reproducing operation was performed. As a result, similar to the first embodiment, high quality recording / reproducing characteristics were obtained.
[0026]
Next, a comparative example will be described.
[Comparative Example 1]
Also in Comparative Example 1, a flexible optical disk is manufactured in the same manner as in Example 1. However, in Comparative Example 1, a polyester resin having a thickness of 100 μm is used as the base film. The clearance between the inner diameter of the large diameter ring 15 and the outer diameter of the small diameter ring 11 is 0.14 mm. Although the thickness of the flexible optical disk substrate 1 is smaller than the clearance of these two rings 15 and 11, ripples are generated over a wide area of the disk surface after the recording film is formed because the tension cannot be applied evenly in the radial direction. did. The roundness of the preformat pattern of the flexible optical disk as the final product is as large as 50 μm.
[0027]
In Comparative Example 1, the reason why the tension cannot be applied evenly in the radial direction to the flexible optical disk substrate 1 is that the clearance between the two rings is insufficient and the flexible optical disk substrate cannot be sandwiched well. is there.
The flexible optical disk 5 was mounted on the evaluation apparatus shown in FIG. 1, and the recording / reproducing operation was performed in the same manner as in the above embodiments. As a result, tracking was easily lost and satisfactory recording / reproduction characteristics could not be obtained.
[0028]
[Comparative Example 2]
Also in Comparative Example 2, a flexible optical disk is manufactured in the same manner as in Example 1. However, in the case of Comparative Example 2, a recording film was formed using a polycarbonate resin having a thickness of 100 μm as a base film while applying tension in the winding direction by a roll-to-roll method. In this case, no ripple was observed, but the roundness of the preformat pattern of the flexible optical disk as the final product is as large as 70 μm.
[0029]
In Comparative Example 2, the cause of the increase in roundness despite the absence of ripples is due to the lack of balance in tension between the winding direction in the roll-to-roll method and the direction perpendicular thereto. .
The flexible optical disk 5 was mounted on the evaluation apparatus shown in FIG. 1, and the recording / reproducing operation was performed in the same manner as in the above embodiments. As a result, tracking was easily lost and satisfactory recording / reproduction characteristics could not be obtained.
[0030]
【The invention's effect】
The effects of the present invention are summarized for each main claim as follows.
1. Advantages of the Inventions of Claims 1 and 2 In the inventions of claims 1 and 2, a recording film or the like is formed on a flexible optical disk substrate onto which a preformat pattern is transferred from a stamper while applying tension in the radial direction. This makes it possible to apply a tension force evenly in the radial direction and prevent random deformation and warping caused by the film-forming stress, so that no ripple occurs and the roundness of the preformat pattern is also high. A good flexible optical disk substrate can be manufactured. In addition, a flexible optical disk having high quality recording / reproducing characteristics can be manufactured.
[0031]
2. The effect of the invention of claim 3 The invention of claim 3 uses a ring having two different diameters to form a recording film or the like while applying tension in the radial direction at a radial position larger than the final disk size. By doing so, the tension can be made uniform in the radial direction. Further, when the recording film is a phase change film, it can be applied to the initialization process while being set in two rings, so that the recording film can be reliably crystallized.
[0032]
3. Effect of Invention of Claim 4 According to the invention of claim 4, the clearance between the inner diameter of the large-diameter ring and the outer diameter of the small-diameter ring is 1.5 to 3.2 times the thickness of the sandwiched flexible optical disk substrate. Sufficient tension in the radial direction can be applied to the flexible optical disk substrate, and a smooth flexible optical disk without ripples can be manufactured.
[0033]
4). Advantages of the invention of claim 5 The invention of claim 5 is a tension force in the radial direction with respect to the flexible optical disk substrate because the knurling is engraved on the upper surface of the small-diameter ring of the two rings having different diameters. When the knurled surface is applied, the surface on which the knurling is carved firmly grips the flexible optical disk substrate, so that a sufficient tension can be given evenly in the radial direction.
[0034]
5. Advantages of the Invention of Claim 6 The invention of claim 6 is characterized in that the knurled is engraved on the inner surface of the large-diameter ring of the two rings having different diameters, so that a stronger tension is applied to the flexible optical disk substrate. Can give power.
[0035]
6). EFFECT OF THE INVENTION OF THE INVENTION According to the invention of the seventh aspect, the knurls carved in the two rings having different diameters are the twill knurls, so that the tension can be applied very effectively.
[0036]
7. Effect of Invention of Claim 8 With respect to the invention of claim 8, the height of the two rings having different diameters is higher in the large-diameter ring than in the small-diameter ring, and the height difference of the flexible optical disc substrate is sandwiched between the rings. When the thickness is larger than the thickness, contact can be avoided even when the target is close to the surface of the flexible optical disk substrate in the film forming process such as a recording film, and the yield in the film forming process can be improved.
[0037]
8). Effect of Invention of Claim 9 The invention of claim 9 is that the electrical specific resistance of two rings having different diameters is 100 μΩ · cm or less, so that sufficient electrical conduction can be obtained and the film formation efficiency can be improved. Therefore, it is possible to increase the cycle of the film forming process. Further, since the ring is difficult to be charged, the adhesion of contaminants can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a flexible optical disk and its drive (evaluation apparatus).
FIG. 2 is a schematic diagram showing a small-diameter ring and a twill knurl carved on one upper surface thereof.
FIG. 3 is a schematic view showing a large-diameter ring and a twill knurled carved on the inner surface thereof.
FIG. 4 is a schematic view of a state in which a flexible optical disk substrate is sandwiched between two rings having different diameters and tension is applied in a radial direction.
[Explanation of symbols]
1: Flexible optical disk substrate 2: Transfer surface 5: Flexible optical disk 11: Small diameter ring 12: Ayame knurl 15: Large diameter ring 16: Ayame knurl 20: Guide 21: Objective lens 22: Spindle

Claims (11)

A method for manufacturing a flexible optical disk substrate, comprising forming a recording film or the like while applying a tension force in a radial direction to a flexible optical disk substrate onto which a preformat pattern is transferred from a stamper. 2. The method of manufacturing a flexible optical disk substrate according to claim 1, wherein a recording film or the like is formed while applying a tension force in a radial direction at a radial position larger than the final disk size. 2. The flexible optical disk according to claim 1, wherein a recording film or the like is formed using two rings having different diameters while applying tension in a radial direction at a radial position larger than the final disk size. A method for manufacturing a substrate. The clearance between the inner diameter of the large-diameter ring and the outer diameter of the small-diameter ring between two rings having different diameters is 1.5 to 3.2 times the thickness of the sandwiched flexible optical disk substrate. The manufacturing method of the flexible optical disk board | substrate of description. 5. The method of manufacturing a flexible optical disk substrate according to claim 3, wherein a knurling is carved on an upper surface of the small-diameter ring among the two rings having different diameters. The method for manufacturing a flexible optical disk substrate according to any one of claims 3 to 5, wherein a knurl is engraved on an inner surface of the large-diameter ring among the two rings having different diameters. 7. The method for manufacturing a flexible optical disk substrate according to claim 5, wherein the knurling carved in the two rings having different diameters is a twill knurling. The height of the two rings having different diameters is larger in the large-diameter ring than in the small-diameter ring, and the height difference is larger than the thickness of the flexible optical disk substrate to be sandwiched. The manufacturing method of the flexible optical disk board | substrate in any one. The method for producing a flexible optical disk substrate according to claim 3, wherein two rings having different diameters have an electric specific resistance of 100 μΩ · cm or less. A flexible optical disk substrate manufactured by the method for manufacturing a flexible optical disk substrate according to claim 1. A flexible optical disk manufactured using the flexible optical disk substrate according to claim 10.

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