JP2005063541A - Optical disk medium, turntable, and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the occurrence of the warpage of an optical disk medium when the optical disk medium is rotatively driven by a turntable. <P>SOLUTION: A disk substrate of the optical disk medium 1 is formed by using a metal substrate 5. When the optical disk medium 1 is mounted on a disk placing surface 3a of the turntable 3, the metal substrate 5 is attracted to the disk placing surface 3a by magnetic force to highly accurately correct the warpage of the optical disk medium 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical pickup medium for recording and / or reproducing data by an optical method or a magneto-optical method, a turntable for rotating the optical disk medium, and an optical pickup while rotating the optical disk medium with a spindle motor. The present invention relates to an optical disc apparatus for recording and / or reproducing data on an optical disc medium.

As is well known, an optical disk medium such as an optical disk or a magneto-optical disk that records and / or reproduces data by an optical method or a magneto-optical method has a data recording layer such as an optical pit or a magnetic film on one or both sides of the disk substrate. A transparent protective layer is coated on the data recording layer.
In general, this optical disk medium is inserted into the outer periphery of the centering convex portion on the turntable by a center hole, chucked and rotated, and data is recorded on the data recording layer by a light beam or magneto-optical. Recording and / or reproduction is performed.

A conventional optical disk medium of this type uses a metal substrate as a disk substrate (for example, Patent Document 1). Instead of forming a center hole in the disk substrate, the center hole of a metal hub attached to the lower surface of the center of the disk substrate is inserted into the spindle at the center of the turntable and chucked to rotate (for example, Patent Documents) 2) is known. Also, an annular (doughnut plate-shaped) printed label is attached to the outer part of the center hole of two upper and lower single-sided optical discs between the inner part of the data recording area (for example, Patent Document 3). is there.
JP-A-11-345412 JP 07-225972 A Japanese Patent Laid-Open No. 08-297867

  The problem to be solved is that when the optical disk medium is rotated by a turntable and data is recorded and / or reproduced by an optical pickup, if the optical disk medium is warped, the optical disk medium is shaken by rotation. As a result, a focus error, a tracking error, and the like occur, so that high density recording / reproduction cannot be performed.

  The present invention is formed of a magnetic material in an optical disk medium in order to correct the warp of the optical disk medium with high accuracy when data is recorded and / or reproduced by an optical pickup while the optical disk medium is rotationally driven by a turntable. The main feature is to provide a metal substrate.

  Since the optical disk medium of the present invention includes a metal substrate formed of a magnetic material, when the optical disk medium is mounted on the disk mounting surface of the turntable, the optical disk medium is placed on the disk mounting surface by a magnetic force. Adsorption can correct the optical disk medium warp with high accuracy, so that the surface shake of the optical disk medium can be kept small during data recording and / or reproduction, and focus errors are unlikely to occur. There is an advantage that reproduction can be performed.

Pictures and characters that can be seen through the data recording layer on one or both sides of a metal substrate for the purpose of drawing and printing on the data recording layer portion of the optical disk medium Etc. realized by a picture / character layer drawn and printed.
The purpose of enabling the optical disk medium to be easily adsorbed on the turntable is realized by a notch that is formed on the outer periphery of the turntable and can be attached to and detached from the outer periphery of the optical disk medium. did.

First, the outline of the main part of the optical disk apparatus of the present invention will be described with reference to FIG.
The optical disk medium 1 of the present invention reproduces (reads) data by a light beam represented by a CD or DVD. However, there is no denying that data is recorded and / or reproduced (read) by a magneto-optical method such as MO. Although details of the optical disk medium 1 will be described later, a metal substrate made of a magnetic material is used as the disk substrate of the optical disk medium 1. A disk substrate of a general optical disk medium is PC (polycarbonate).

Next, a turntable 3 is fixed to the tip of the motor shaft 2a of the spindle motor 2 by press-fitting, bonding, screwing or the like, and details of the turntable 3 will be described later. It consists of
The turntable 3 is magnetized with N and S poles in the thickness direction so that the optical disk medium 1 is attracted (fixed) onto the disk mounting surface 3a of the turntable 3 by the magnetic force MF. It is configured.

The optical disk medium 1 is rotated integrally with the turntable 3 by a spindle motor 2, and data (signal) recorded concentrically on one or both surfaces of the optical disk medium 1 is a light beam emitted from the optical pickup 4. It is read by a certain laser beam LB (reproduction).
At this time, the optical disk medium 1 of the present invention differs from a general optical disk medium in that a center hole is not formed and the optical disk medium 1 extends over a wide range from the outer periphery to the center, as will be described in detail later. Since data is recorded, the optical pickup 4 reads the data while accessing the optical disk medium 1 in the radial direction (arrow Aa, b direction) over a wide range from the outer periphery to the center.
At this time, since the turntable 3 exists on the entire lower surface side of the optical disk medium 1, the optical pickup 4 reads data from the upper side opposite to the turntable 3 of the optical disk medium 1.

Next, details of the optical disk medium 1 of the present invention will be described with reference to FIGS. 3 is a cross-sectional view illustrating details of the optical disc medium 1 on which data is recorded on only one side, and FIG. 4 is a cross-sectional view illustrating details of the optical disc medium 1 on which data is recorded on both sides.
Therefore, the disk substrate of the optical disk medium 1 is composed of a metal substrate 5 made of a magnetic material such as a thin metal disk. For example, SUS430 (a stainless steel material having magnetism) having a thickness of 0.5 mm or less can be applied to the metal substrate 5.

  A picture / character layer 6 on which a picture or a character is drawn / printed is formed on one side or both sides of the metal substrate 5. Further, a data recording layer 7 made of a UV resin (ultraviolet curable resin) layer is formed on the picture / character layer 6. In this data recording layer 7, data 7a is formed concentrically with a concavo-convex shape having a depth of about 50 to 130 nm called a pit. 3 and 4 schematically show the concave and convex shape as the data 7a, but in practice, the shape of the data 7a is so small that it can hardly be identified with the eyes. It is something that looks flat at first glance. The pits are the same as those used for ROM disks such as CDs and DVDs, and are general signal recording information for optical disks.

  When the data recording layer 7 is formed, first, a UV resin layer is applied on the picture / character layer 6 and then a transparent stamper (a die for forming pits) is pressed onto the UV resin layer. Hit it. Next, in this state, the UV resin layer is irradiated with UV (ultraviolet rays) from above to cure the UV resin layer, thereby forming pits, that is, the data recording layer 7. The thickness T of the data recording layer (= UV resin layer) 7 at this time is 20 μm or more.

Further, in the optical disk medium 1, a reflective film 8 capable of transmitting light by sputtering is formed on the data recording layer 7 (on the pit surface). Examples of the material of the reflective film 8 include aluminum, an aluminum alloy, silver, a silver alloy, and silicon.
The reflection film 8 is a thin film having a thickness of about 10 to 20 nm, and functions as a reflection film for the laser beam LB irradiated from the optical pickup 4 described above while maintaining the pit shape of the data recording layer 7.

Since the reflection film 8 is a thin film, the reflection film 8 is a film having a partial light transmittance with a reflectance of about 10 to 30%.
Therefore, the picture and characters of the picture / character layer 6 formed on the surface of the metal substrate 5 can be viewed through the reflective film 8.

  On the reflective film 8, a cover coat 9 is formed as a protective layer made of a transparent UV resin material or the like. The cover coat 9 is formed into a thin film by, for example, a spin coating method and is cured by UV irradiation.

  The optical pickup 4 irradiates the laser beam LB from the cover coat 9 side of the optical disc medium 1 through the objective lens 4a. The laser beam LB transmitted through the cover coat 9 is reflected by the reflection film 8 and returns to the optical pickup 4. The recorded signal can be read by the change in the amount of reflected light due to the pits in the data recording layer 7. This is the same principle as CD and DVD.

  As shown in FIG. 4, in the optical disk medium 1 on which signals are recorded on both sides, after making the single-sided disk shown in FIG. 3, the steps after the formation of the data recording layer 7 are repeated. Can be created by applying to the back side.

  The optical disk medium 1 of the present invention has a feature that the optical disk medium 1 itself is attracted by a magnet because the disk substrate is formed on a magnetic metal substrate 5. Conventional optical disk media, for example, use a metal piece called a magnet called a hub attached to a disk for MD (mini disk), or a disk fixing mechanism such as a disk clamper for CD or DVD. . However, according to the present invention, a magnet attracting hub, a disc clamper, and the like are not required, and the optical disc medium 1 can be attracted to the disc mounting surface 3a by the magnetic force MF of the turntable 3 alone.

  That is, as shown in FIG. 1, the turntable 3 is magnetized at a position corresponding to the disk mounting surface 3a of the turntable 3 made of a magnetic material so that the north and south poles are directed in the vertical direction. Is formed into a magnet. Then, since the metal substrate 5 of the optical disk medium 1 is attracted to the turntable 3 side by the magnetic force MF of the magnet, the optical disk medium 1 is attracted horizontally (parallel) on the disk mounting surface 7a of the turntable 3. Can do.

At that time, since the entire metal substrate 5 of the optical disk medium 1 is adsorbed in parallel on the disk mounting surface 7a of the turntable 3, the warp of the optical disk medium 1 is corrected and the flatness of the entire optical disk medium 1 is remarkably increased. improves.
Therefore, when the data pickup layer 7 is irradiated with the laser beam LB by the optical pickup 4 and the reflected light is read, the focus error can be reduced, and the data can always be read with high accuracy.

  In addition, since the metal substrate 5 is used for the disk substrate as compared with the conventional optical disk medium in which the disk substrate is made of PC (polycarbonate) such as general CD and DVD, the rigidity of the entire optical disk medium 1 is improved. Go up. This produces an advantage that the thickness of the entire optical disk medium 1 can be reduced as compared with equivalent disk rigidity.

  When the optical pickup 4 performs signal reproduction, it is desired to read only the light reflected by the reflective film 8. However, since the reflecting film 8 is a partially transmissive reflecting film, the transmitted light generates unnecessary reflected light in the picture / character layer 6.

  Therefore, in the present invention, unnecessary reflected light is reduced by increasing the thickness T of the UV resin layer (data recording layer 7) (= the distance between the picture / character layer 6 and the reflective film 8) (FIG. 5). The laser beam LB focused on the reflective film 8 is diffused on the picture / character layer 6 and projected with a larger light diameter as the UV resin layer (data recording layer 7) is made thicker. The Therefore, the amount of unnecessary reflected light Lb2 reflected by the picture / character layer 6 leaks into the necessary reflected light Lb1 reflected by the reflective film 8, and the data reading accuracy is remarkably improved. can do.

  Taking a two-layer recording disk actually used in a DVD or the like as an example, reproduction is possible with a distance of 20 μm between the first and second layers of the reflective film. As long as an interval of at least 20 μm is provided, even if unnecessary reflected light from another layer exists, the system has a proven track record. The reflective film 8 is partially transparent, and the UV resin layer (data recording layer 7) is thickened to a level at which unnecessary reflected light Lb2 from the picture / character layer 6 does not cause a problem (20 μm or more). ) Makes it possible to print pictures and characters on the signal recording side of the disc. In the prior art, printing was possible on the back surface of the signal recording surface, but it was impossible to print on the signal recording surface side.

Further, as another feature of the optical disk medium 1 of the present invention, since the disk surface is covered with the cover coat 9 which is a protective layer, there is no shape irregularity on the disk surface, and the disk surface can be formed on a smooth surface. . As shown in the overall view of the disk in FIG. 2, it can be mentioned that there is no center hole (hole at the center of the disk).
In the conventional optical disk medium, a center hole for performing centering is indispensable when the disk is fixed to the spindle motor.

However, in the optical disk medium 1 of the present invention, as will be described later, the structure of the turntable 3 of the spindle motor 2 enables the optical disk medium 1 to be centered without a center hole. Further, by eliminating the center hole, the data recording layer 7 can be greatly expanded to the disc center portion 1b, and as a result, the recording capacity can be increased.
That is, FIG. 6A shows a general optical disc medium 101 having a center hole such as a CD or DVD, and the center hole 102 is opened at the center of the disc. The diameter on the inner circumference side of the data recording area 107 formed from the outer circumference portion 103 to the inner circumference portion of the disc cannot be reduced, and there is a limit to increasing the recording capacity.

However, in the optical disk medium 1 of the present invention, as shown in FIG. 6B, since the center hole is not opened at the center of the disk, the diameter of the data recording layer 7 from the disk outer peripheral part 1a to the disk central part 1b is 0. The recording capacity can be greatly increased up to about 5 mm toward the center of the disk, and the recording capacity can be greatly increased.
Further, in the conventional optical disk apparatus, the data recording surface of the optical disk medium 1 rotated by the turntable 3 is generally faced downward, and data is read from the lower side of the optical disk medium 1 by an optical pickup. When trying to reduce the inner diameter of the data recording area 102, the optical pickup interferes with the spindle motor, and there is a limit to the expansion of the recording capacity.

However, the optical disc apparatus of the present invention accesses the optical pickup 4 to the inner circumference of the disc by arranging the spindle motor 2 and the optical pickup 4 on opposite sides of the optical disc medium 1 as described in FIG. However, the optical pickup 4 and the spindle motor 2 do not interfere with each other. Therefore, the data recording layer 7 can be enlarged by having no center hole in the optical disk medium 1 and allowing the optical pickup 4 to access the central portion 1b of the optical disk medium 1 without any interference with the spindle motor 2. Thus, the recording capacity can be increased.
FIG. 7A shows a general optical disk medium 101 having a center hole such as a CD or a DVD, in which a picture / character layer is formed by drawing / printing. 106 is greatly limited by the center hole 102 opened at the center of the disk, and the entire area occupied by the disk including the center hole 102 portion cannot be effectively used to display pictures, characters, etc. large and effectively. .

  However, since the optical disk medium 1 of the present invention has no center hole as shown in FIG. 7B, the picture / character layer 6 is spread over a wide area within the entire occupied area including the central portion 1b of the optical disk medium 1. Can be formed. Therefore, the display of pictures, characters, etc. is not limited by the center hall, and the pictures, letters, etc. can be displayed large and effectively, and the aesthetics and product value of the optical disk medium can be greatly improved. Can do.

Next, the turntable 3 of the present invention will be described with reference to FIGS.
The turntable 3 of the present invention is integrally formed with a magnet (bonded magnet, sintered magnet or the like), and has a magnetic force MF in which the N pole and the S pole are magnetized in the vertical direction. As another feature, the outer diameter of the turntable 3 is larger than the outer diameter of the optical disk medium 1, and a cylindrical rib 10 for centering the optical disk medium 1 is concentric on the outer periphery of the disk mounting surface 3a. Are integrally molded. As shown in FIG. 1, the optical disk medium 1 is positioned so that its outer diameter matches the inner diameter of the rib 10, and is attracted to the disk mounting surface 3a by the magnetic force MF. The outer diameter of the optical disk medium 1 and the inner diameter of the rib 10 are designed with a gap of about 100 μm in consideration of the component tolerances.

  Even with this centering method, centering accuracy within ± 100 μm can be obtained, and centering can be performed with the same accuracy as the centering method using the conventional center hole. The rib 10 also serves as a stopper for preventing the optical disc medium 1 from protruding in the circumferential direction during rotation. By this method, even the optical disc medium 1 without the center hole can be centered with high accuracy on the turntable 3 with the same accuracy as the conventional one.

  8 and 9, the turntable 3 of the present invention has chamfers 11 at the corners of the inner peripheral surface 10a and the upper surface 10b of the rib 10, so that the optical disk medium 1 is placed inside the rib 10. When being inserted into the disk and attracted (attached) onto the disk mounting surface 3a, the outer periphery of the optical disk medium 1 can be guided by the chamfer 11 and smoothly guided to the inside of the rib 10. Therefore, the mounting operation of the optical disk medium 1 on the disk mounting surface 3a of the turntable 3 can be performed smoothly.

  The height of the rib 10 is equal to or less than the thickness of the optical disc medium 1. When the optical disk medium 1 is attached to or detached from the turntable 3, the optical pickup 4 moves further outward than the outermost circumference of the disk in order to improve operability. At this time, if the height of the rib 10 is higher than the disc thickness, a portion close to the optical disc medium 1 such as the objective lens 4 a of the optical pickup 4 may be caught by the rib 10 when moving in the radial direction of the turntable 3. Because there is. If the height of the rib 10 is lower than the thickness of the optical disc medium 1, there is no possibility of being caught.

  Further, one or a plurality of notches 14 are formed on the outer peripheral portion of the turntable 3. This is a portion where a finger for grasping the optical disk medium 1 enters when the optical disk medium 1 is attached to or detached from the turntable 3. Without this notch 14, the rib 10 of the turntable 3 gets in the way and it is particularly difficult to remove the optical disk medium 1.

  In the present invention, the optical disk medium 1 has a wide surface from the inner periphery to the outer periphery, and has a method of being attracted to the turntable 3 by the magnetic force MF. In this method, even if the optical disk medium 1 is warped, the optical disk medium 1 is forcibly copied to the highly rigid disk mounting surface 3a side by the attractive force of the magnetic force MF. This means that if the flatness of the disc mounting surface 3a is improved, the flatness of the optical disc medium 1 is corrected to a good state even when the optical disc medium 1 has a large warp in actual use. Therefore, by improving the flatness of the disk mounting surface 3a over the specifications of surface runout and flatness determined by the standard of the optical disk medium 1, there is an effect of reducing the warp of the optical disk medium 1 in actual use. is there. In other words, it is possible to relax the standard related to the warp of the optical disc medium 1.

Further, as shown in FIGS. 8 to 10, in the turntable 3 of the present invention, an annular recess 12 that is a relief in the height direction is formed on the outer peripheral portion of the disk mounting surface 3 a. This recess 12 is a recess 12 for escape because a portion where the thickness of the disc becomes thicker by about 50 μm or less is formed within a range of 1 to 2 mm from the outer peripheral edge of the optical disc medium 1.
That is, as shown in FIG. 10, in the optical disc medium 1, the cover coat 9 is formed by the spin coat method as described above. In the spin coating method, a film is formed by using centrifugal force. However, only the outermost peripheral portion of the optical disc medium 1 has UV resin accumulated due to the surface tension, and a raised portion 15 is formed where the film becomes thick. There is a nature to end up. Without the escape recess 12, when the optical disk medium 1 is attracted to the disk mounting surface 3 a of the turntable 3, the rising portion 15 rides on the disk mounting surface 3 a (interference occurs). ), The warp of the optical disk medium 1 may increase.

  FIG. 11 shows a second embodiment of the present invention. The turntable 3 is formed of a magnetic material such as an iron material by using a magnetic force MF magnetized on the metal substrate 5 of the optical disk medium 1. The disc is placed on the disk mounting surface 3a.

  FIG. 12 shows a third embodiment of the present invention, in which the optical disk medium 1 is placed on the disk of the turntable 3 by the magnetic force MF of a plurality of magnets 18 embedded in the disk placement surface 3 a of the turntable 3. It is configured to be adsorbed on the surface 3a. In this case, the turntable 3 can be formed of a non-magnetic body such as plastic.

FIG. 13 shows a fourth embodiment of the present invention, which is at least one of the upper and lower surfaces of the optical disc medium 1, and in the case of a single-sided disc, the lower surface side (the surface opposite to the data recording layer 7). In the case of a double-sided disc, annular ribs 1c and 1d are formed on the outer peripheral portion and / or the inner peripheral portion of the optical disc medium 1 on both the upper and lower sides.
If such annular ribs 1c and 1d are formed on the optical disk medium 1, the cover coat 9, the picture / character layer 6 and the like are provided even if the optical disk medium 1 is inadvertently placed on a desk or the like. Injuries can be prevented in advance.

  FIG. 14 shows a fifth embodiment of the present invention, in which annular ribs 3b and 3c are formed on the outer peripheral portion and the inner peripheral portion of the disc mounting surface 2a of the turntable 3, and the optical disc medium 1 is formed. It is intended to be placed horizontally on the inner and outer annular ribs 3b, 3c. Thus, the entire disk mounting surface 3a of the turntable 3 may not be a single plane.

The present invention is not limited to the above-described embodiments, and various effective modifications can be made based on the technical idea of the present invention.
The optical disk medium of the present invention is not limited to an optical disk that records and / or reproduces data by an optical system, but can also be applied to a magneto-optical disk that records and / or reproduces data by a magneto-optical system.
Further, according to the optical disk medium of the present invention, the presence or absence of the center hole is not questioned.

It is a partially cutaway side view showing the main part of the optical disk apparatus of the present invention. FIG. 2 is a plan view and a side view showing the entire optical disc medium of the present invention. It is sectional drawing which expanded and showed the principal part at the time of applying the optical disk medium of this invention to a single-sided disk. It is sectional drawing which expanded and showed the principal part at the time of applying the optical disk medium of this invention to a double-sided disk. FIG. 4 is an enlarged cross-sectional view of a main part for explaining that unnecessary reflected light from a picture / character layer does not enter into necessary reflected light by increasing the thickness of the data recording layer of the optical disk medium of the present invention. . It is a top view explaining the difference in recording capacity of the optical disk medium of the present invention and a general optical disk having a center hole. It is a top view explaining the difference in the display area of a picture, a character, etc. with the optical disk medium of this invention, and the general optical disk which has a center hole. It is a top view explaining the turntable of the present invention. It is a partially cutaway side view of FIG. It is an expanded sectional view of the principal part explaining the bulging part of the outer peripheral part of the optical disk medium of this invention, and the dent for escape of the turntable with respect to the bulging part. It is sectional drawing explaining the 1st modification of this invention. It is sectional drawing explaining the 2nd modification of this invention. It is sectional drawing explaining the 3rd modification of this invention. It is sectional drawing explaining the 4th modification of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk medium 2 Spindle motor 2a Motor shaft 3 Turntable 3a Disk mounting surface 4 Optical pick-up 5 Metal substrate 6 Picture and character layer 7 Data recording layer 8 Reflective film 9 Cover coat (protective layer)
12 dent 14 notch 16 annular rib 17 annular rib MF magnetic force

Claims (14)

It has a metal substrate that corrects the flatness of the disc,
An optical disk medium, wherein the metal substrate is formed of a magnetic material. The picture / character layer in which a picture or a character that can be seen through a data recording layer is drawn / printed is formed on one side or both sides of the metal substrate. Optical disk medium. 3. The optical disk medium according to claim 2, wherein a reflective film capable of partially transmitting light is formed on an upper layer of the data recording layer. 4. The optical disk medium according to claim 3, wherein a distance between the reflective film and the picture / character layer is set to a thickness of about 20 [mu] m or more. One side of the disc is formed with a picture / character layer that can be seen through the data recording layer,
2. The optical disk medium according to claim 1, wherein a picture / character layer is also formed on the other surface of the disk. The optical disk medium according to any one of claims 1 to 5, wherein a protective layer capable of transmitting light is formed on at least a surface on the side where the picture / character layer exists. The optical disc according to any one of claims 1 to 6, wherein an annular rib is formed on an upper surface, a lower surface, or both upper and lower surfaces of any one of the outer peripheral portion and the inner peripheral portion. Medium. In the turntable on which the optical disk medium according to any one of claims 1 to 7 is mounted on a disk mounting surface,
The turntable, wherein the optical disk medium is attracted onto the disk mounting surface by a magnetic force. 9. The turntable according to claim 8, wherein the optical disk medium is adsorbed on the disk mounting surface by a magnetic force magnetized on the turntable side. The turntable is formed of metal;
The turntable according to claim 8, wherein the optical disk medium is attracted onto a disk mounting surface of the turntable by a magnetic force magnetized on the metal substrate. 9. The turntable according to claim 8, wherein a notch for pinching and detaching a part of the outer periphery of the optical disk medium is formed on the outer periphery of the turntable. 9. The turntable according to claim 8, wherein the flatness of the disc mounting surface of the turntable is higher than the flatness standard of the optical disc medium. The turntable according to claim 8, wherein an annular recess is formed in an outer peripheral portion of a disk mounting surface of the turntable. The optical disk medium according to any one of claims 1 to 6 is mounted on the turntable according to any one of claims 7 to 13, and rotates the turntable. An optical disc apparatus comprising: a spindle motor; and an optical pickup for recording and / or reproducing data on the optical disc medium rotated and driven by the turntable.

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