JPH0675345B2 - Information recording medium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an information recording medium to which a hub provided with a magnetic sensitive material is joined. More specifically, the present invention relates to an information recording medium in which the hub provided with the above-mentioned magnetic sensitive material is joined with high dimensional accuracy.

[Technical Background of the Invention] In recent years, information recording media using a high energy density beam such as a laser beam have been developed and put into practical use. This information recording medium is called an optical disc, and is a video disc, an audio disc, a large-capacity still image file, and a large-capacity computer disc.
It can be used as a memory.

The optical disc has a disk-shaped transparent resin substrate made of plastic, glass or the like as a basic structure, and a recording layer provided thereon. On the surface of the substrate on which the recording layer is provided, an undercoat layer or an intermediate layer made of a polymer substance is used in order to improve the flatness of the substrate, the adhesive force with the recording layer, the sensitivity of the optical disk, and the like. May be provided.

Currently, with respect to an optical disc having a diameter of 130 mm (5.25 inches), an information recording medium using a hub (magnetically sensitive hub) is defined by the ISO standard. The hub plays a role as a disc clamp for mounting and fixing the optical disc when the optical disc is rotationally driven by a recording and reproducing device, and is provided with a magnetic sensitive material such as a metal piece.
It is fixed by magnetic force.

The hub has a hole for inserting a spindle in the center, and generally has a cylindrical portion and a sleeve portion. The cylindrical portion is inserted into and bonded to a through hole formed in the center of the information recording disk. The hub is assembled so as to be concentrically joined to the center of the disc-shaped information recording disk.

Conventionally, the joining of the hub to the information recording disk is rotatable.
Fix the disc on the XY table, and while rotating it, observe the group formed on the information recording disc with a microscope etc. to determine the center of the information recording disc, and determine the center of the group, that is, the center of the information recording disc. The XY table was adjusted so that the centers of the rotation axes coincided, and then a hub set coaxially with the center of the rotation axis of the information recording disk was joined. Examples of the joining method include a method using an adhesive and an ultrasonic fusion method.

In the information recording medium provided with the magnetically sensitive hub, the joining position of the hub is adjusted as in the manufacturing method described above.
Therefore, in the conventional hub, the diameter of the cylindrical portion of the fitted hub is smaller than the through hole of the information recording disk so that the joining position can be adjusted, or
It was one of the types without a cylinder. Therefore, when the hub and the information recording disk are joined together, eccentricity (deviation between the center of the information recording disk and the center position of the spindle insertion hole) is likely to occur.

According to the ISO standard, the eccentricity is specified to be within 25 μm.

However, in the manufacturing method in which the hub is joined by finding the center of the information recording disc, most of the operation is performed manually, and the joining accuracy greatly depends on the skill of the operator. Assembling time for each medium takes several minutes, and there is a problem that productivity is poor. On the other hand, attempts have been made to automatically perform a series of centering operations (to find the center of the information recording disk) by a machine, but the processing system for the centering operation is complicated and the manufacturing cost is high. And even in that case, the productivity could not be significantly increased.

[Object of the Invention] An object of the present invention is to provide an information recording medium excellent in dimensional accuracy, productivity and optical characteristics.

SUMMARY OF THE INVENTION According to the present invention, a circular hole is provided in a center of a data recording disk, which is capable of writing and / or reading information by a laser. An information recording medium having a magnetically sensitive hub having a hole for use as a magnetically sensitive hub, wherein the diameter of the base and the tip of the cylindrical portion is smaller than the diameter of the circular hole,
A magnetically sensitive hub in which projections are formed at least at three locations on the outer wall surface of the cylindrical portion, and the diameter of a virtual circle formed by connecting the tops of the projections is larger than the diameter of the circular hole. The information recording medium is characterized by being joined to the circular hole while being supported by the convex portion and fitted in the circular hole.

Preferred embodiments of the information recording medium of the present invention are as follows.

(1) The information recording medium as described above, characterized in that as the magnetically sensitive hub, a magnetically sensitive hub having convex portions formed at three points on the outer surface of a cylindrical portion at 120 ° intervals is used.

(2) As a magnetically sensitive hub, the diameter of the circle formed by the top of the convex portion formed on the outer surface of the cylindrical portion is made larger than the diameter of the circular hole of the information recording disk within the range of 1 to 25 μm. The information recording medium as described above, wherein a hub is used.

(3) The information recording medium as described above, wherein the cylindrical portion of the magnetically sensitive hub is formed by three or more column portions arranged discontinuously and symmetrically to each other.

DETAILED DESCRIPTION OF THE INVENTION Representative aspects of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view showing an example of a hub (magnetically sensitive hub) which is a characteristic element of the present invention.

The hub 10 includes a cylindrical portion 11 and a sleeve portion 12. The diameter of the base portion 13 and the tip portion 14 of the cylindrical portion 11 is smaller than the diameter of the circular hole of the information recording disk.

On the outer wall surface 15 of the cylindrical part 11, three convex parts 1 are formed at 120 ° intervals.
6 are formed. It is particularly preferable that the convex portion is formed near the base portion 13 of the cylindrical portion 11, and the wall portion 17 of the convex portion 16 on the distal end portion 14 side is an inclined surface as shown in the figure. It is preferable.

The diameter of the circle formed by the top portion 18 of the convex portion 16 is preferably larger than the diameter of the circular hole of the information recording disk within the range of 1 to 25 μm, and larger than the range of 5 to 15 μm. Is particularly preferable.

FIG. 2 is a perspective view showing another example of the hub. Hub 20
Comprises a cylindrical portion 21 and a sleeve portion 22. The diameter of the base portion 23 and the tip portion 24 of the cylindrical portion 21 is smaller than the diameter of the circular hole of the information recording disk.

On the outer wall surface 25 of the cylindrical portion 21, three convex portions 2 are provided at 120 ° intervals.
6 are formed. It is particularly preferable that the convex portion is formed near the base portion 23 of the cylindrical portion 21, and the wall portion 27 of the convex portion 26 on the tip end 24 side is an inclined surface as shown in the figure. It is preferable.

The diameter of the circle formed by the top portion 28 of the convex portion 26 is preferably larger than the diameter of the circular hole of the information recording disk within the range of 1 to 25 μm, and larger than the diameter of 5 to 15 μm. Is particularly preferable.

Further, the cylindrical portion 21 has a notch (slit) 29. According to the study by the present inventor, when the cylindrical portion has a notch, the convex portion is easily bent toward the center of the circular hole of the information recording disk during fitting, and the fitting is accompanied by pressing into the circular hole. Matching becomes easy. The notches are preferably formed on both sides of the protrusion along the protrusion. The notch can be formed at any depth from the tip to the base of the cylindrical portion.

FIG. 3 is an inclined view showing an example of a hub (magnetically sensitive hub) which is a characteristic element of the present invention.

The hub 30 is composed of a pillar portion 31 and a sleeve portion 32 which are arranged in a discontinuous and symmetrical relationship with each other to form a cylindrical portion. Base portion 33 and tip portion 34 of column portion 31 forming a cylindrical portion
Is smaller than the diameter of the circular hole of the information recording disk. An enlarged perspective view of the column portion 31 is shown in FIG. 3A.

The pillar portions 31 are arranged at three positions at 120 ° intervals, and the convex portions 36 are formed on the surface thereof. The convex portion is particularly preferably formed near the base portion 33 of the column portion 31, and the tip portion
The wall portion 37 of the convex portion 36 on the 34 side is preferably an inclined surface as shown.

The diameter of the circle formed by the top 38 of the protrusion 36 is preferably larger than the diameter of the circular hole of the information recording disk within the range of 1 to 25 μm, and larger than the range of 5 to 15 μm. Is particularly preferable.

FIG. 4 is a sectional view showing an example of the information recording medium of the present invention.

The information recording medium 40 of the present invention has two disc-shaped information recording disks 43a, 43b having circular holes 41a, 41b in the center and recording layers 42a, 42b formed on the surfaces, and recording layers 42a, 42b. With the inner side as the inner side, and the inner side ring-shaped spacer 44 and the outer side ring-shaped spacer 45 are joined.

Hubs 48a and 48b having magnetic sensitive bodies 46a and 46b and spindle insertion holes 47a and 47b are joined to the centers of both side surfaces of the joined two information recording disks 43a and 43b.
The hubs 48a and 48b are the information recording disks 43a and 43b, respectively.
Is joined by ultrasonic fusion without eccentricity.

Next, referring to FIG. 5 attached, an example of a method for manufacturing the information recording medium 40 of the present invention shown in FIG. 4 will be described.

FIG. 5 shows that, of the two disc-shaped information recording discs 43a, 43b joined via the inner ring-shaped spacer 44 and the outer ring-shaped spacer 45, the magnetic sensitive material 46a is provided on the information recording disc 43a side. FIG. 6 is a cross-sectional view illustrating an example in which a hub 48a provided with a spindle insertion hole 47a is fusion-bonded using an ultrasonic fusion machine 49. In FIG. 5, recording layers 42a and 4a
Disc-shaped information recording disks 43a and 43b, which are bonded to each other with the inner ring-shaped spacer 44 and the outer ring-shaped spacer 45 on the inside of 2b, are arranged on the receiving jig 50.

A hub 48a is arranged in the center of the information recording disk 43a. At this time, only the tip portion 53 of the cylindrical portion 52 of the hub 48a fits in the circular hole 41a in the center of the information recording disk 43a. Since the tip portion 53 of the cylindrical portion 52 of the hub 48a is thinner than the circular hole 41a at the center of the information recording disk 43a, the tip portion 53 of the cylindrical portion 52 can be easily inserted into the circular hole 41a.

Next, the hub 48a is fusion-bonded to the center of the information recording disk 43a by using the ultrasonic fusion machine 49. Ultrasonic fusion machine 4
Reference numeral 9 includes an application horn 54 for applying ultrasonic waves, and ultrasonic waves are oscillated from an ultrasonic oscillator 55 and transmitted to the ultrasonic application horn 54 via a converter 56. For fusion bonding of the hub 48a to the information recording disk 43a, first, the ultrasonic wave application horn 54 of the ultrasonic fusion machine 49 is lowered to move the hub.
The ultrasonic wave is applied from the ultrasonic wave application horn 54 while pressing the ring-shaped projection 51 against the information recording disk 43a by pressing the ring 48a.

In the hub 48a, the wall portion 59 of the convex portion 58 on the tip portion 53 side is an inclined surface, and is gradually fitted and joined to the circular hole 41a of the information recording disk 43a by the pressing of the ultrasonic wave application horn 54. To be done.

As mentioned above, the wall of the convex portion on the tip end side of the cylindrical portion is
In the case of the inclined surface, the hub gradually fits firmly into the circular hole of the information recording disk by pressing. Therefore,
The information recording medium of the present invention can be manufactured with high accuracy even by the ultrasonic fusion method as described above, which tends to cause eccentricity (deviation of the center position) of the hub due to vibration of ultrasonic waves.

In the above, the information recording medium explained in the attached drawings complies with the present invention, but is not limited to the above-mentioned constitution.

For example, the convex portion formed on the cylindrical portion of the hub may be formed at three or more places.

Further, the tip of the cylindrical portion of the hub may be chamfered or rounded.

The hub may be joined using an adhesive,
Alternatively, only the fitting may be performed.

The optical disc may be a so-called magneto-optical disc having a recording layer formed of a magnetic layer.

Well-known spacers, hubs, substrates, and recording layers that make up the information recording medium of the present invention can be used as desired, so these will be briefly described below.

The material of the spacer is not particularly limited, and a metal such as a known spacer such as aluminum and a synthetic resin can be used. The spacer can be manufactured by injection molding in the case of synthetic resin, and can be manufactured by rolling or cutting in the case of metal such as aluminum.

The hub (magnetically sensitive hub) is not particularly limited as long as it can be satisfactorily bonded to the disk-shaped substrate by the ultrasonic fusion method, and examples thereof include thermoplastic resins such as polycarbonate resin, polyacrylic resin and acetal resin. it can. Further, the hub is preferably made of the same material as the disk-shaped substrate in consideration of the thermal expansion coefficient and the hygroscopic expansion coefficient.

The magnetic material required for the construction of the hub (magnetic hub) is iron,
It consists of a magnetically sensitive material such as an alloy containing iron,
It is preferably made of a substance that is resistant to rust. The form of the magnetic sensitive material is not particularly limited, but a typical form is a magnetic sensitive piece having a rod shape, a plate shape, a ring shape, or the like, and a magnetic sensitive powder obtained by pulverizing the magnetic sensitive material. it can. It is also possible to knead the magnetically sensitive powder into the material of the hub and perform injection molding.

The substrate used in the present invention can be arbitrarily selected from various materials conventionally used as substrates for information recording media. From the viewpoint of optical characteristics, flatness, processability, handleability, temporal stability and manufacturing cost of the substrate, examples of the substrate material include cell cast polymethylmethacrylate, injection molded polymethylmethacrylate, polymethylacrylate and the like. Preferable examples include acrylic resins; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; amorphous polyolefin resins; and synthetic resins such as polycarbonate. Among these, polymethylmethacrylate, polycarbonate, and epoxy resin are preferable from the viewpoints of dimensional stability, transparency and flatness.

The surface of the substrate on which the recording layer is provided has improved flatness,
An undercoat layer (and / or an intermediate layer) may be provided for the purpose of improving the adhesive force and preventing the deterioration of the recording layer.

Examples of the material for the undercoat layer (and / or intermediate layer) include polymeric substances such as polymethylmethacrylate, acrylic acid / methacrylic acid copolymer, nitrocellulose, polyethylene, chlorinated polyolefin, polypropylene, and polycarbonate; silane cups. Examples thereof include organic substances such as ring agents; and inorganic substances such as inorganic oxides (SiO ₂ , Al ₂ O ₃ etc.) and inorganic fluorides (MgF ₂ ).

Examples of materials used for the recording layer include Te, Zn, In, S
Examples thereof include metals such as n, Zr, Al, Ti, Cu, Ge, Au and Pt; semimetals such as Bi, As and Sb; semiconductors such as Si; and alloys or combinations thereof.

Further, compounds such as sulfides, oxides, borides, silicon compounds, carbides and nitrides of these metals, semimetals or semiconductors; and mixtures of these compounds with metals can also be used in the recording layer. Alternatively, combinations of dyes, dyes and polymers, dyes and the metals and metalloids listed above can be utilized.

The recording layer may further contain various metals, semimetals or compounds thereof known as recording layer materials.

The recording layer can be formed on the substrate directly by a method such as vapor deposition, sputtering, ion plating, coating or the like through the undercoat layer. The recording layer may be a single layer or multiple layers, but the layer thickness is generally in the range of 100 to 5500Å, preferably in the range of 150 to 1000Å, from the viewpoint of optical density required for optical information recording.

An inorganic material such as silicon dioxide, tin oxide, or magnesium fluoride is formed on the surface of the substrate opposite to the side on which the recording layer is provided in order to improve scratch resistance and moisture resistance.
A thin film made of a polymer material such as a thermoplastic resin or a photocurable resin may be provided by a method such as vacuum deposition, sputtering or coating. Furthermore, the recording layer may be provided in a joining region with the spacer other than the recording region.

EFFECTS OF THE INVENTION The information recording medium of the present invention is easy to manufacture in the manufacturing process, since it is not necessary to determine the center of each information recording disk and join the hubs as in the conventional case. ,
In addition, the manufacturing time is short and it is suitable for mass production.

Furthermore, the information recording medium of the present invention has excellent dimensional accuracy and is stable.

Furthermore, in the information recording medium of the present invention, the hub fits in a state in which the hub is in contact with the through hole of the information recording disk only by the convex portion formed on the cylindrical portion. Therefore, the hub is joined to the information recording disk without substantially affecting the birefringence of the information recording disk.

[Brief description of drawings]

FIG. 1, FIG. 2 and FIG. 3 are perspective views showing examples of hubs used in the information recording medium of the present invention. FIG. 3A is a column portion in the perspective view of the hub shown in FIG.
31 is an enlarged perspective view of FIG. FIG. 4 is a sectional view showing an example of the information recording medium of the present invention. FIG. 5 is a diagram illustrating an example of a method for manufacturing the information recording medium of the present invention. 10, 20, 30, 48a, 48b: Hub (magnetically sensitive hub) 11, 21, 52: Cylindrical part 31: Pillar part 12, 22, 32: Sleeve part 13, which is arranged so as to form the cylindrical part 23, 57: Base part (of cylinder part) 33: Base part (of pillar part) 14, 24, 53: Tip part (of cylinder part) 34: Tip part (of pillar part) 15, 25: Outer part (of cylinder part) Walls 16, 26, 36, 58: Convex portions 17, 27, 37, 59: (Convex portion) Wall portions 18, 28, 38: (Convex portion) Top portion 29: Notch portion (slit) 40: Information recording medium 41a, 41b: Circular holes 42a, 42b: Recording layers 43a, 43b: Information recording disk 44: Inner ring spacer 45: Outer ring spacer 46a, 46b: Magnetosensitive material 47a, 47b: Spindle insertion hole 49: Ultrasonic fusing machine 50: Receiving jig 51: Ring-shaped protrusion (energy director) 54: Ultrasonic wave application horn 55: Ultrasonic oscillator 56: Converter

Claims (2)

[Claims] 1. An information recording disk capable of writing and / or reading information by a laser having a circular hole in the center, the circular hole having a cylindrical portion and a sleeve portion, and having a spindle insertion hole in the center. An information recording medium in which a magnetically sensitive hub is mounted, wherein the magnetically sensitive hub has a base portion and a tip portion of the cylindrical portion having a diameter smaller than that of the circular hole, and at least three locations on the outer wall surface of the cylindrical portion, A magnetically sensitive hub in which a convex portion is formed and the diameter of an imaginary circle formed by connecting the tops of the respective convex portions to each other is larger than the diameter of the circular hole is supported by the convex portion to the circular hole. An information recording medium characterized by being joined in a fitted state. 2. The magnetically sensitive hub according to claim 1, wherein the cylindrical portion is formed by three or more column portions arranged discontinuously and symmetrically to each other. Information recording medium.