JP2006179122A - Thin optical disk manufacturing method and manufacturing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for effectively suppressing the eccentric amount of a disk in a thin optical disk manufacturing method and manufacturing apparatus in which a pattern and a recording film are formed on one or both surfaces while a sheet is unwound and the disk is continuously punched out. To do.
An identifier (marker) for alignment is formed on each surface of a substrate sheet simultaneously with pattern formation, and the center position of the pattern formed on each surface is read immediately before the punching process. And a manufacturing method and apparatus for setting a punching position so that the eccentricity on both sides of the disk is as small as possible.
[Selection] Figure 1

Description

  The present invention relates to a method and apparatus for manufacturing a flexible thin optical disk, and in particular, in a manufacturing method in which a pattern and a recording film are formed on one or both sides while a sheet is unwound, and the disk is continuously punched. The present invention relates to a technique for effectively suppressing the amount of eccentricity.

  As the information society advances and it becomes necessary to store a huge amount of information, the recording density of the external storage device has been remarkably improved. Regarding optical discs, there are studies to improve the recording density by shortening the laser wavelength and reducing the size of the focused light spot by increasing the numerical aperture of the objective lens, or increasing the transmittance of the recording layer to increase the recording density. It is actively done. In addition, research on improving recording density by improving hologram recording and volume recording density has become active. However, since light is absorbed by each layer in the so-called multilayer recording method, it is considered that the number of layers is practically the limit of multilayering, and the recording density is expected to be improved by narrowing the spot in the hologram recording method. Therefore, it is extremely difficult to realize a terabyte-class recording capacity with these recording methods. On the other hand, magnetic tape has already achieved a terabyte-class recording capacity. However, a magnetic tape is a recording medium that cannot be randomly accessed, such as an optical disk, and has a drawback that an access time becomes very long in order to read and write a large amount of information.

  As a terabyte-class recording medium that can overcome such a situation, can be accessed randomly, has a short access time, and can be manufactured in a small size and at a low cost, it is thinner than a substrate used in conventional optical recording media and magnetic recording media. A disk cartridge containing a plurality of optical disks and magnetic disks has been proposed. As an example, Patent Documents 1 and 2 describe an optical disc cartridge in which a plurality of optical discs each having a recording layer formed on one surface thereof are stacked and accommodated.

  Various techniques for manufacturing a thin optical disk have also been proposed. Patent Document 3 describes a single-wafer thin optical disc manufacturing process in which a recording film is formed after stacking a plurality of flexible sheets punched out from each other in the form of a disk. On the other hand, a manufacturing method in which a substrate is continuously punched while unwinding a roll-shaped sheet has also been implemented. In this manufacturing method, a thin optical disk is manufactured by forming a pattern and a recording layer on one or both sides of a sheet and then punching it into a disk shape.

Japanese Patent Application Laid-Open No. 2004-134019. JP 2001-35008 A. JP2003-228890A.

  The manufacturing method in which the substrate is continuously punched while unwinding the roll-shaped sheet has the advantages of low manufacturing cost and high speed. However, on the other hand, there is a possibility that the pattern and recording layer formed on one or both sides of the sheet may be eccentric. Therefore, a technique for suppressing the occurrence of eccentricity in the manufacturing process is indispensable in order to prevent a decrease in yield. . For example, in the case of manufacturing a double-sided recording type thin optical disk, if only one side is used as a reference, the center of the disk may be largely shifted from the other side. Further, even when a single-sided recording type thin optical disk is manufactured, it is necessary to prevent eccentricity between substrates that are continuously punched.

  The present invention has been made in view of such circumstances, and a method and an apparatus for manufacturing a thin optical disk in which a pattern and a recording film are formed on one side or both sides while a sheet is unwound and the disc is continuously punched out. Therefore, it is intended to provide a technique for effectively suppressing the eccentricity of the disk.

  As a result of diligent research in view of the above problems, the inventor formed an identifier (marker) for alignment at the same time as pattern formation on each surface of the substrate sheet, and the identifier of each surface was immediately before the punching process. The inventors have come up with a manufacturing method and a manufacturing apparatus that determine the center position of the pattern formed on each surface by reading with a sensor or the like and set the punching position so that the eccentricity on both sides of the disk is as small as possible.

  That is, the present invention includes a step of forming a pattern on both sides of a substrate sheet, a step of forming a recording film on both sides of the substrate sheet, a step of forming an overcoat on both sides of the substrate sheet, and a step of punching a disk from the substrate sheet. A method for manufacturing a thin optical disk, comprising: forming an identifier for identifying a position of a pattern on each surface of the substrate sheet in the pattern forming step; and after the pattern forming step and before the punching step. (Preferably immediately before the punching step) The identifier is read from each surface of the substrate sheet, and the eccentricity between the two patterns is within a certain range based on the position of the pattern formed on each surface of the substrate sheet recognized from the identifier. The present invention provides a method for manufacturing a thin optical disk, wherein the punching position of the disk is determined so as to be inside.

  In the method for producing a thin optical disk of the present invention, in the pattern forming step, three or more identifiers are formed at a position away from the center of the pattern by a certain length, and when the identifier is read, the position of each identifier is determined. From this, the center position of the pattern is recognized. Based on the positional relationship between the center positions of the patterns formed on each surface of the substrate sheet, it is possible to determine the punching position of the disk so that the amount of eccentricity between both patterns is reduced. The specific method is as follows.

  (1) The center point of the punching position of the disc is set on the line segment connecting the center positions of the patterns formed on the respective surfaces of the substrate sheet recognized from the read identifier.

  (2) The substantially midpoint of the line segment connecting the center positions of the patterns formed on each surface of the substrate sheet recognized from the read identifier is set as the center point of the disc punching position.

  (3) The center point of the punching position of the disk is set in an area where circles of a certain radius drawn around the center position of the pattern formed on each surface of the substrate sheet recognized from the read identifier overlap.

  The present invention also includes means for forming a pattern and an identifier for identifying the position of the pattern on both sides of the substrate sheet, means for forming a recording film on both sides of the substrate sheet, and means for forming an overcoat on both sides of the substrate sheet. The identifier is read from each surface of the substrate sheet, and the disc punching position is determined based on the position of the pattern formed on each surface of the substrate sheet recognized from the identifier so that the eccentricity between the two patterns is within a certain range. An apparatus for producing a thin optical disk, comprising: a means for carrying out the process; and a means for punching a disk from a substrate sheet at the punching position.

  In the thin optical disk manufacturing apparatus of the present invention, the pattern forming unit forms three or more identifiers at a position away from the center of the pattern by a certain length, and the disk punching position determining unit reads the identifiers. Further, the center position of the pattern is recognized from the position of each identifier. The disk punching position determining means can determine a disk punching position that reduces the amount of eccentricity between both patterns based on the positional relationship between the center positions of the patterns formed on each surface of the substrate sheet. The specific method is as follows.

  (1) The center point of the punching position of the disc is set on the line segment connecting the center positions of the patterns formed on the respective surfaces of the substrate sheet recognized from the read identifier.

  (2) The substantially midpoint of the line segment connecting the center positions of the patterns formed on each surface of the substrate sheet recognized from the read identifier is set as the center point of the disc punching position.

  (3) The center point of the punching position of the disk is set in an area where circles of a certain radius drawn around the center position of the pattern formed on each surface of the substrate sheet recognized from the read identifier overlap.

  As described above, according to the present invention, a disk and an eccentricity of a thin optical disk are continuously formed by forming a pattern and a recording film on one or both surfaces while unwinding a sheet, and continuously punching the disk. Techniques for effectively reducing the amount are provided. This makes it possible to mass-produce high-quality and inexpensive thin optical disks.

  Hereinafter, the best mode for carrying out a method and apparatus for manufacturing a thin optical disk according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 8 are diagrams illustrating embodiments of the present invention. In these drawings, the same reference numerals denote the same components, and the basic configuration and operation are the same. To do.

  FIG. 1 is a diagram schematically showing each manufacturing process of the thin optical disk of the present embodiment. In FIG. 1, a thin optical disk is manufactured through a pattern forming process, a recording film forming process, an overcoat forming process, and a punching process. In the present embodiment, the above-described steps are performed on both sides of a thin optical disk, and a double-sided recording type thin optical disk is manufactured.

  A sheet material made of PET (polyethylene terephthalate) having a thickness of 100 μm is used for a thin optical disk substrate. In the pattern forming process, both surfaces of the substrate are simultaneously heated and pressed to form a pattern shape having a track pitch of 0.65 μm, a depth of 54 nm, a half-value land of 280 nm, and a half-value groove of 370 nm. The track eccentricity is 50 μm. In the recording film forming step, a recording film such as a MAMMOS (Magnetic AMplifying Magneto-Optical System) film is formed on both surfaces of the substrate by sputtering or the like. In the overcoat forming step, an overcoat made of a UV resin layer or the like having a thickness of about 15 μm is formed on both surfaces of the substrate. Finally, in the punching process, a disk-shaped thin optical disk is punched from the substrate sheet material on which the pattern, the recording film, and the overcoat are formed. The thin optical disk has an inner diameter of 15 mm and an outer diameter of 100 mm, and the inner and outer peripheral sides are punched simultaneously.

  As shown in FIG. 1, the present embodiment is characterized in that a pair of punching position control devices for adjusting the punching positions with respect to each surface of the thin optical disk in the punching process are provided. Each punching position control device reads an identifier (hereinafter referred to as a “marker”) included in the pattern on the substrate sheet immediately before the punching process using an optical sensor or the like, and controls the punching position according to the position information of the read identifier. To do. FIG. 2 is a flowchart showing the flow of the manufacturing process of the thin optical disk according to the present embodiment including the punching position control. As shown in FIG. 2, in the present embodiment, a pattern is formed on both surfaces of the substrate sheet (step S21), a recording layer is formed (step S22), an overcoat is formed (step S23), and immediately before punching. In the state, the marker position on each surface of the substrate sheet is read (step S24), the punching position is adjusted according to the read marker position information (step S25), and punching is performed (step S26).

  FIG. 3 is a diagram illustrating an arrangement example of markers formed on each surface of the thin optical disk. In FIG. 3A, four markers are arranged outside the outer periphery of the punched portion of the thin optical disc, and in FIG. 3B, three markers are arranged inside the outer periphery of the punched portion of the thin optical disc. Also, marker arrangements other than those shown here are possible. Since the marker can be read even if the recording layer is formed thereon, it can also be formed in the recording layer. Three or more arbitrary numbers of markers are formed, and each marker is arranged at an equidistant position from the center of the pattern formed on the thin optical disk.

  The punching position control of the thin optical disk by the punching position control device described above is performed so as to minimize the amount of eccentricity between patterns formed on each surface of the thin optical disk. Hereinafter, the control method will be described.

First Method A first method for determining the punching position of a thin optical disk will be described with reference to FIG. Hereinafter, one surface of the thin optical disk is referred to as Side0, and the other surface is referred to as Side1. First, the punching position control device reads the positions of the markers formed on the Side 0 and Side 1 of the thin optical disc, and obtains the center positions D _0c and D _1c of the patterns formed on the Side 0 and Side 1 from the positions of the markers. Since three or more markers are arranged on each surface of the thin optical disk, a point equidistant from each marker can be set as the center position of the pattern. In the example shown in FIG. 4, three of the three D _1c point equal distance d1 from marker D _0c, Side1 point equal distance d0 from markers Side0 are obtained, respectively.

When the center positions D _0c and D _1c of the patterns in Side 0 and Side 1 of the thin optical disk are obtained, the midpoint of the line segment connecting D _0c and D _1c is set as the center of the punching position. This is because the amount of eccentricity between the patterns formed on each surface is minimized by punching the thin optical disk around this position. Actually, there may be variations in the center position of the punching. Even in such a case, the punching center position is as much as possible on the line segment D _0c D _1c after examining the variation pattern. If it controls so that it may become, it can suppress the amount of eccentricity between the patterns formed in each surface of a thin optical disk as much as possible.

In FIG. 4, the distance between D _0c and D _1c is set large for easy understanding, but in practice, the distance between D _0c and D _1c is almost as shown in FIG. The allowable range is about several tens of μm. At this time, the two circles are almost overlapped. However, if the values of d0 and d1 are different from each other to some extent, it is easy to distinguish a circle centered on D0c and a circle centered on D1c. It becomes.

Second Method A second method for determining the punching position of the thin optical disk will be described with reference to FIGS. In the second method, an allowable eccentricity range is set for each of Side0 and Side1, and the center of the punching position is set based on the range. First, the punching position control device reads the positions of the markers formed on the Side 0 and Side 1 of the thin optical disc, and obtains the center positions D _0c and D _1c of the patterns formed on the Side 0 and Side 1 from the positions of the markers.

Now, in each of Side0 and Side1, assumed to be set in the range of eccentricity is allowed area included in a circle with a diameter R around the D _0c, and D _1c. In this case, punching the center position where the Side0 and Side1 both within the allowable range of the eccentric, it is understood that the region overlapping the two circles of diameter R was respectively around the D _0c, and D _1c. Therefore, by setting the punching center position in this overlapping region, the amount of eccentricity between the patterns formed on each surface of the thin optical disk can be kept within an allowable range. In practice, there may be variations in the punching center position. Even in such a case, the punching center position is within the overlapping region of two circles as much as possible after examining the variation pattern. If the control is performed so as to fit, the amount of eccentricity between patterns formed on each surface of the thin optical disk can be suppressed as much as possible.

As apparent from FIGS. 6 and 7, the line segment D _0c D _1c must be shorter than R in order to have a region where two circles centering on D _0c and D _1c overlap. Those that do not satisfy this condition are preferably excluded as defective products.

  Here, the value of R that defines the allowable amount of eccentricity will be described with a specific example. For example, in the specification of a commercially available DVD-R, the track pitch is 0.8 ± 0.04 μm, and the maximum allowable track eccentricity is 50 μm. In the future, in order to realize higher density recording, it is considered that specifications with a further reduced track pitch will appear. For example, when the track pitch is 0.5 μm, the track tracking accuracy required to stably perform recording and reproduction by avoiding crosstalk or erroneous writing between adjacent tracks is generally 1/10 or less of the track pitch, That is, 0.05 μm. The track can be followed with an accuracy of 0.05 μm, and if the servo gain value is 60 dB, an eccentric amount up to 1000 times the track pitch can be generally allowed. Therefore, it can be seen that the allowable eccentricity in the thin optical disk is in a range where R = 50 μm at the maximum. However, as the recording medium is further increased in density, this R value needs to be further reduced.

  As mentioned above, although the specific embodiment was shown and demonstrated about the manufacturing method and manufacturing apparatus of the thin optical disk of this invention, this invention is not limited to these. A person skilled in the art can make various changes and improvements to the configurations and functions of the invention according to the above-described embodiments or other embodiments without departing from the gist of the present invention.

  For example, the material of the recording film is not limited to MAMMOS, and a phase change film or a dye film may be used as the recording film. Further, the shape of the pattern, the inner diameter and the outer diameter of the disk can be changed as appropriate. Further, FIG. 1 shows a manufacturing process including one row of manufacturing lines in a substrate sheet shape. For example, as shown in FIG. 8, as a manufacturing process including a plurality of manufacturing lines in a substrate sheet shape, Also good. In this case, the punching position control device individually controls the punching positions of each row on each side of the substrate. The sensor of the punching position control device is most preferably installed immediately before the punching process from the viewpoint of improving the accuracy of the punching position control, but it should be installed at an arbitrary position from the pattern forming process to before the punching process. Can do.

It is a figure which shows roughly each manufacturing process of the thin optical disk of this invention. It is a flowchart which shows the flow of the manufacturing process of the thin optical disk of this invention. It is a figure which shows the example of arrangement | positioning of the marker formed in each surface of a thin optical disk. It is a figure which shows notionally the 1st method of determining the punching position of a thin optical disk. It is a figure which shows notionally the 1st method of determining the punching position of a thin optical disk. It is a figure which shows notionally the 2nd method of determining the punching position of a thin optical disk. It is a figure which shows notionally the 2nd method of determining the punching position of a thin optical disk. It is a figure which shows roughly the modification of each manufacturing process of the thin optical disk of this invention.

Claims (10)

Forming a pattern on both sides of the substrate sheet;
Forming a recording film on both sides of the substrate sheet;
Forming an overcoat on both sides of the substrate sheet;
A method of manufacturing a thin optical disk including a step of punching a disk from a substrate sheet,
In the pattern forming step, an identifier for identifying the position of the pattern is formed on each surface of the substrate sheet, and after the pattern forming step and before the punching step, the identifier is read from each surface of the substrate sheet, A method of manufacturing a thin optical disk, wherein the punching position of the disk is determined based on the position of the pattern formed on each surface of the substrate sheet recognized from the identifier so that the eccentricity between both patterns is within a certain range. .   In the pattern forming step, three or more identifiers are formed at a position away from the center of the pattern by a predetermined length, and when the identifier is read, the center position of the pattern is recognized from the position of each identifier. 2. The method of manufacturing a thin optical disk according to claim 1, wherein   3. A thin optical disk according to claim 2, wherein the center point of the punching position of the disk is taken on a line segment connecting the center positions of the patterns formed on each surface of the substrate sheet recognized from the read identifier. Manufacturing method.   The center point of the punching position of the disc is defined as a substantially midpoint of a line segment connecting the center positions of the patterns formed on each surface of the substrate sheet recognized from the read identifier. Of manufacturing a thin optical disk.   The center point of the punching position of the disc is taken in a region where circles of a certain radius drawn around the center position of the pattern formed on each surface of the substrate sheet recognized from the read identifier overlap. The method for producing a thin optical disk according to claim 2. Means for forming an identifier for identifying the pattern and the position of the pattern on both sides of the substrate sheet;
Means for forming a recording film on both sides of the substrate sheet;
Means for forming an overcoat on both sides of the substrate sheet;
The identifier is read from each surface of the substrate sheet, and the disc punching position is determined based on the position of the pattern formed on each surface of the substrate sheet recognized from the identifier so that the eccentricity between both patterns is within a certain range. Means,
An apparatus for producing a thin optical disk, comprising means for punching a disk from a substrate sheet at the punching position. The pattern forming means forms three or more identifiers at a position away from the center of the pattern by a certain length,
7. The apparatus for manufacturing a thin optical disk according to claim 6, wherein the disk punching position determining means recognizes the center position of the pattern from the position of each identifier when the identifier is read.   The disk punching position determining means takes the center point of the disk punching position on a line segment connecting the center positions of the patterns formed on the respective surfaces of the substrate sheet recognized from the read identifier. The apparatus for manufacturing a thin optical disk according to claim 7.   The disk punching position determining means uses a substantially midpoint of a line segment connecting the center positions of the patterns formed on each surface of the substrate sheet recognized from the read identifier as a center point of the disk punching position. 8. The apparatus for manufacturing a thin optical disk according to claim 7,   The disk punching position determining means is configured to determine the center of the disk punching position in a region where circles of a certain radius drawn around the center position of the pattern formed on each surface of the substrate sheet recognized from the read identifier overlap. The apparatus for manufacturing a thin optical disk according to claim 7, wherein a point is taken.

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