JP2001093194A - Substrate for information recording disk and information recording disk as well as cartridge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information recording disk which detains a hub in a loose fitting state and is narrowed in the spacing from a recording surface to a disk reference plane. SOLUTION: A substrate 1 has a recessed part 3 housing the hub 2 in a the loose fitting state in its central part. An inner peripheral wall 3a of the recessed part 3 in which the hub 2 is housed is projected from the recording surface 6 in the rotating axis direction of the disk, by which an annular rib 4 is formed. The position of the hub 3 in the radial direction of the disk is regulated by the inner peripheral wall 3a of the recessed part 3. The position of the hub 2 in the rotating axis direction is regulated by the inside wall of an upper cartridge 31. The information recording disk produced by using such substrate may be made narrower in the spacing from the disk reference plane 8 to the recording surface 6 than heretofore. Further, the cartridge for housing such information recording disk may be formed thinner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording disk substrate manufactured by an injection molding method, an information recording disk manufactured using the same, and a cartridge device. The present invention relates to an information recording disk substrate, an information recording disk, and a cartridge device of a type in which a hub is magnetically attracted to a magnet and locked.

[0002]

2. Description of the Related Art With the advent of the multimedia era, information recording disks such as optical disks and magneto-optical disks are widely used as recording media capable of recording and reproducing vast amounts of information such as music, moving images, and computer data. It's being used. Some of these information recording disks have a hub at the center of the disk for supporting and rotating the disk by the drive device. The hub at the center of the disk is connected to a magnet provided on the disk rotation mechanism of the drive device. The disk is fixed to the turntable by magnetic attraction. As a method of mounting the hub at the center of the information recording disk, for example, a method of bonding an insert molded hub obtained by previously inserting the hub into a mold and performing injection molding to the disk using an ultraviolet curing resin, A method of fixing to a disk by welding means using ultrasonic waves has been used.

In recent years, in a small and inexpensive information recording disk represented by, for example, a mini disk (MD), as shown in FIG. 5, a concave portion 53 formed in a central portion of a base 51 of the information recording disk is provided. The hub 52 is accommodated in a loosely fitted state, and the inner peripheral edge of the concave portion 53 is thermally deformed by ultrasonic waves to form a projection 4a.
The method of locking the hub 52 in the recess 53 with a is adopted. According to this method, a metal hub can be manufactured only by stamping press working, and therefore, an expensive insert molding die is not required. Also, when a metal hub is attached to the information recording disk, it can be locked in an extremely short time by vibrating and deforming the plastic of the disk base using an ultrasonic welding machine. Therefore, this is an advantageous means in that the manufacturing cost can be reduced. Furthermore,
Since the hub is locked in a loosely fitted state, even when the information recording disk is subject to a temperature change, the linear expansion coefficient of the hub and the disk has been a problem in the mounting method of directly bonding the hub to the disk. There is no local stress on the disk due to the difference.

[0004]

As shown in FIG. 5, in an information recording disk of the type in which a hub is loosely fitted, a disk for locking the information recording disk to a disk rotating mechanism is used. Unless a sufficient space is provided between the disk reference surface 58 and the lower surface 52c of the hub 52 as the support area, a problem may occur that the disk may be displaced from the rotation shaft during rotation or the center hole of the disk may not be inserted into the rotation shaft. . In particular, an information recording disk having an outer diameter of 64 mm or less, for example, a mini disk, is employed in a state in which the disk is loaded into a drive device while being housed in a resin cartridge. In order to securely mount the hole on the rotation shaft of the rotation mechanism of the drive device, the distance from the disk reference surface to the lower surface of the hub is at least 1.5 m.
m or more was required. Furthermore, in a single-plate information recording disk having a substrate thickness of 0.7 mm or less, in order to secure the interval of 1.5 mm or more, the dimension from the disk reference surface to the recording surface becomes large. In some cases, mold release failures occur when the resin is manufactured by injection molding. Further, the above-mentioned interval has caused a difficulty in reducing the thickness of the cartridge accommodating the information recording disk.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has as its object to lock a hub in a disk in a loosely fitted state and to reduce a dimension from a disk reference surface to a recording surface. An object of the present invention is to provide an information recording disk substrate that can be made smaller and that can prevent mold release failure during injection molding.

Another object of the present invention is to realize a thin cartridge for accommodating an information recording disk.

[0007]

According to a first aspect of the present invention, a disk-shaped base has a columnar recess in which a hub is accommodated in the center of the surface, and a spindle is inserted into the bottom of the recess. In the information recording disk substrate in which the hole to be formed is formed coaxially with the base, the inner peripheral wall of the recess extends in the direction of the rotation axis of the base so as to protrude from the surface of the base. An information recording disk substrate is provided.

The information recording disk substrate of the present invention has a concave portion in the center portion in which the hub is accommodated in a loosely fitted state, and protrudes from the inner peripheral end of the concave portion in the direction of the rotation axis from the recording surface of the substrate to form a ring. Ribs are defined. When the hub is loosely accommodated in the recess, the radial position of the hub is regulated by the inner peripheral wall of the recess. An information recording disk manufactured using such a substrate can be housed in a cartridge device for regulating the position of the hub in the direction of the rotation axis.

On the other hand, in the case of an information recording disk of a type which is not contained in a cartridge but is loaded in a drive device, the inner peripheral wall extends in order to regulate the position of the hub in the direction of the rotation axis contained in the recess. A protruding portion protruding from the portion in the direction of the rotation axis may be provided. Such protrusions can be formed by, for example, thermally deforming the distal end of the inner peripheral wall extension using an ultrasonic welding machine. of course,
The information recording disk provided with the projection can be used by being housed in a cartridge device.

In the present invention, the material constituting the hub is:
In order to securely attract the hub to the magnet provided on the spindle, for example, SUS is preferably 400 series, and SUS430 is particularly preferred in terms of manufacturing cost. Here, as shown in FIG. 10A, the depth of the recess for accommodating the hub is x, the thickness of the hub is a, and there is a play for locking the hub in a loosely fitted state with the disk substrate. b, When a projection is formed on the inner peripheral wall extending portion by welding (FIG. 10B)
), Let c be the welding margin (the thickness of the projection in the direction of the rotation axis), and x be the sum of each x = a + b +
It is set in (c). The thickness a of the hub is determined by the attraction force to the magnet provided on the spindle, that is, the clamping force, and is desirably selected within the range of 0.3 mm to 0.5 mm. The play b for locking the hub in the loosely fitted state is sufficient if an amount capable of absorbing the difference in linear expansion coefficient between the material forming the disc substrate and the material forming the hub is secured, and is 0.1 mm to 0.2 mm. Is preferably within the range. Further, the welding margin c is determined by the locking strength of the hub. If the welding margin is small, the locking strength is insufficient, and the hub is detached from the disc by an impact such as dropping. Is preferably selected in the range.

On the other hand, in order to secure the depth x of the concave portion and the thickness of the concave portion in which the hub is accommodated to obtain sufficient strength, the distance from the lower surface of the bottom portion of the concave portion to the surface of the base must be one. It is preferable to select in the range of 0.3 mm to 1.6 mm. Even if this interval is smaller than 1.3 mm, the annular rib needs a certain height in order to securely mount the spindle in the center hole of the disk.
It is difficult to reduce the thickness of the cartridge. If the distance exceeds 1.6 mm, it is difficult to form an annular rib to reduce the thickness of the cartridge.

With this, even in the case of a relatively thin information recording disk having a recording portion having a thickness of 0.7 mm or less, for example, approximately 0.6 mm, the axial dimension from the disk reference surface to the recording surface can be reduced. Can be. Therefore, it is possible to reduce the thickness of the cartridge in which the information recording disk is housed.

According to a second aspect of the present invention, a cylindrical member having a bottom portion for supporting a hub, and a disk-shaped base portion extending radially outward from an outer peripheral wall of the cylindrical member are provided. An information recording disk substrate, comprising: a base portion extending radially outward from an outer peripheral wall position lower than a top portion of an outer peripheral wall of a cylindrical member in a height direction of the cylindrical member. A disk substrate is provided.

As shown in FIG. 9, the substrate according to the second aspect of the present invention has a radial direction from a position slightly lowered from an open end (top) 92b of an outer peripheral wall 92a of a cylindrical member 92 having a bottom surface 93. It has a structure in which the base 91 extends outward in a disk shape. By adjusting the extending position of the base 91 in this way, the surface 91a of the base 91 can be made lower than the position of the open end 92b of the cylindrical member 92 as shown in FIG. Thereby, the disc reference surface 9
Since the distance from the substrate 4 to the base surface 91a can be reduced, the cartridge for accommodating the information recording disk manufactured using such a substrate can be reduced in thickness.
A hub can be accommodated in the cylindrical member 92 constituting the substrate 91 in a loosely fitted state. The radial position of the hub is cylindrical member 9
2 is regulated by the inner wall 92c.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the information recording disk and the cartridge device according to the present invention will be specifically described below, but the present invention is not limited to these embodiments.

[0016]

Embodiment 1 An example of an information recording disk according to the present invention will be specifically described with reference to FIGS. FIG. 1 shows a cartridge device (20) in a case where the information recording disk 100 accommodated in the cartridge 30 is mounted on the turntable 20 of the information recording disk drive.
FIG. 2 is a schematic cross-sectional view of FIG.
1 is a partially enlarged cross-sectional view of the left side near 1; The information recording disk 100 includes a substrate 1 and a hub 2 as shown in FIG. The substrate 1 has a disk shape having an outer diameter of 50 mm, and is manufactured by injection molding a polycarbonate resin using an injection molding machine (not shown). The substrate 1 has a recording unit on which signals are recorded, and has a recess 3 in the center of the substrate 1 in which a hub is accommodated. Here, the concave portion 3 can be regarded as a space defined by a cylindrical member having a bottom surface formed in the central portion of the substrate. A center hole 9 is formed on the bottom surface of the recess 3, and a bottom surface (hub support surface) 3 b of the recess 3 located radially outside the center hole 9.
Supports the outer peripheral portion of the hub 2. The recess 3 is formed with a play so that the diameter thereof is slightly larger than the outer diameter of the hub 2, and the hub 2 is slightly movable in the radial direction in the recess 3. Referring to FIG. 2, an annular rib 4 is formed at the end of the concave portion 3 on the opening side and is flush with the inner peripheral wall 3 a of the concave portion 3 and protrudes toward the central axis direction (upward in the figure). I have. The annular rib 4 is formed such that the inner peripheral wall 3 a
And extending in the central axis direction so as to protrude therefrom. The position of the top of the annular rib 4 is higher than the position of the recording portion surface (recording surface) 6 of the base 1 in the center axis direction. A plurality of grooves and a plurality of concave and convex marks on which address information is recorded are formed on the recording surface 6, and the thickness of the substrate in the recording unit 5 is approximately 0.6 mm. A recording or reproducing laser beam enters from below in FIG. 1 and transmits through the inside of the substrate 1 to irradiate the recording surface 6 to record or reproduce information.

The hub 2 is made of a SUS material.
As shown in FIG. 1, a central portion has a protruding portion 2a curved in a convex shape, and a flange portion 2c is formed on the outer periphery. When the spindle is inserted into the center hole 9 of the substrate 1, the magnet 22 embedded in the spindle 20a
The magnet 2 is magnetically attracted, and the flange portion 2c of the hub 2 is pressed against the bottom surface 3b of the concave portion.

The cartridge 30 mainly comprises an upper cartridge 31, a lower cartridge 32, and a shutter 33. An opening 34 is formed in the lower cartridge 32. Before the cartridge device is mounted on the driving device (not shown), the opening 34 is covered with the shutter 33. However, when the cartridge device is mounted on the driving device, the shutter is opened by an opening mechanism (not shown), and the opening is opened. The spindle 20 a of the turntable 20 is inserted into the portion 34.

The turntable 20 positions the information recording disk substrate 1 in the radial direction by inserting a spindle 20a of the turntable 20 into the center hole 9. Further, the positioning of the substrate 1 in the rotation axis direction is performed as follows.
The rotation is performed on the lower surface (disk reference surface) 8 of the concave bottom surface portion (clamp step portion) 7 of the substrate 1 with respect to the rotation axis reference surface 23 of the turntable 20. At this time, the hub 2 is connected to the spindle 20a.
It is magnetically attracted by the magnet 22 embedded therein, and is locked to the turntable 20 while maintaining a constant gap between the upper surface of the magnet 22 and the back surface of the protrusion 2 a of the hub 2. Thus, even when the spindle 20a rotates at a high speed about the rotation shaft 21, the information recording disk substrate 1 does not come off the turntable 20.

In the information recording disk detached from a driving device (not shown), the hub 2 is held in a recessed state 3 formed in the inner peripheral portion of the substrate 1 in a loosely fitted state, and the annular rib 4 causes the hub 2 in the disk radial direction. Is regulated. In particular, even when the hub 2 moves upward in the cartridge 30 and the upper surface of the hub 2 comes into contact with the inner wall of the upper cartridge 31, the annular rib 4 regulates the radial position of the hub 2. Therefore, the hub 2 does not come out of the recess 3 outside. Further, the information recording disk of this example has a small thickness of 1.3 mm from the disk reference surface 8 to the recording surface 6. Thereby, as shown in FIG.
The distance from the lower surface 1a of the substrate 1 to the inner surface 33a of the shutter 33a provided in the lower cartridge 32 can be made smaller than before, and as a result, the cartridge 30 for accommodating the information recording disk is made thinner than before. be able to. Therefore, the information recording disk of this example is very suitable for carrying and saving space.

[0021]

Embodiment 2 FIGS. 3 and 4 show a second example of an information recording disk according to the present invention. The information recording disk substrate of this example is a type of information recording disk substrate that is not housed in a cartridge and has an outer diameter of 50 mm as in Example 1, and was manufactured by injection molding of a polycarbonate resin. Next, while the hub 2 is housed in the recess 3 of the substrate 1, the substrate 1 is removed using an ultrasonic welding machine (not shown).
The distal end of the annular rib 4 located at the boundary between the concave portion 3 and the recording portion 5 was vibrated to generate heat, thereby forming a welding convex portion 4a projecting radially inward. In this information recording disk, as shown in FIG. 4, the position of the hub 2 in the disk radial direction is regulated by the inner wall 3a of the concave portion 3, and the direction perpendicular to the recording surface 6 (central axis direction) by the welding convex portion 4a. The position of is regulated. Thus, the hub 2 does not come off from the recess 3 even if it is not housed in the cartridge 30. Although not illustrated, the information recording disk of the present embodiment can be used by being housed in the cartridge 30 shown in the first embodiment.

[0022]

Comparative Example 1 FIGS. 5 and 6 show examples of a conventional information recording disk. The substrate for an information recording disk of this example had an outer diameter of 50 mm and a thickness of a recording portion of 0.6 mm, and was formed by an injection molding method. A concave portion 53 for accommodating the hub is formed in the central portion of the substrate 51, and no annular rib is formed at the boundary between the concave portion 53 and the recording portion 55. Example 2
Similarly to the above, in a state in which the hub 52 is housed in the concave portion 53, the inner peripheral portion of the concave portion 53 is heated and deformed by heating using an ultrasonic welding machine (not shown), so that the hub 52 projects toward the center direction. The welding projection 4a was formed. In this case, although the hub 52 is loosely engaged with the concave portion 53, as shown in FIG.
Up to 1.7 mm. For this reason, it is difficult to reduce the thickness of the cartridge accommodating such an information recording disk due to the restriction on the dimensions.

[0023]

Comparative Example 2 FIGS. 7 and 8 show another example of a conventional information recording disk. The information recording disk substrate of this example is a disk that is not housed in a cartridge and has an outer diameter of 5 mm.
0 mm, the thickness of the recording portion was 0.6 mm, and obtained by injection molding a polycarbonate resin by an injection molding method. A recess 3 in which a hub 2 is accommodated in the center of the substrate 1
Are formed, and no annular rib is formed at the boundary between the concave portion 3 and the recording portion 5. Further, in this example, the welding projection 4a was formed by an ultrasonic welding machine, and the hub 2 was fixed to the substrate 1. As shown in FIG. 8, the information recording disk obtained in this way has a dimension as thin as 1.3 mm from the disk reference surface 8 to the recording surface 6. However,
Since the substrate 1 made of resin has a higher linear expansion coefficient than the hub 2 made of metal, when the temperature of the information recording disk changes, local stress is applied to the substrate 1 by the metal hub 2. There is a possibility that optical birefringence or mechanical deformation may occur in the recording unit 5.

Although the information recording disk of the present invention has been described with reference to the embodiments, the present invention is not limited to this. For example, in the information recording disc,
A material for information recording such as a magnetic material, a phase change material, and an organic dye can be formed on the recording surface. Thereby, optical disks such as a magneto-optical disk, a phase change optical disk, and a write-once optical disk can be manufactured. Further, the material forming the substrate is not limited to the polycarbonate resin, and for example, a resin such as polyolefin, polymethyl methacrylate, polystyrene, nylon, or the like, glass, ceramic, or the like can be used.

[0025]

According to the present invention, the hub can be engaged with the disk in a loosely fitted state, and the distance from the disk reference surface to the recording surface in the disk rotation axis direction can be made narrower than before. Can be made thinner. The substrate of the present invention is:
It is suitable for a substrate for a relatively small-diameter information recording disk in which the thickness of a recording section is reduced to 0.6 mm or less for higher density.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an information recording disk according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view near the central axis of the information recording disk shown in FIG.

FIG. 3 is a schematic sectional view of an information recording disk according to a second embodiment of the present invention.

FIG. 4 is a partially enlarged sectional view of the information recording disk shown in FIG. 3 in the vicinity of a central axis.

FIG. 5 is a schematic sectional view of a conventional information recording disk.

6 is a partially enlarged cross-sectional view of the information recording disk shown in FIG. 3 in the vicinity of a central axis.

FIG. 7 is a schematic sectional view of a conventional type information recording medium having a hub fixed to a substrate.

8 is a partially enlarged cross-sectional view of the information recording disk shown in FIG. 7 in the vicinity of the central axis.

FIG. 9 is a diagram for explaining the structure of the substrate according to the second embodiment of the present invention, and is a partially enlarged cross-sectional view near the central axis.

FIG. 10 is a diagram for explaining the depth of a recess in which a hub is housed.

[Explanation of symbols]

 Reference Signs List 1 information recording disk substrate 2, 52 hub 3, 53 concave portion 4 annular rib 4a welding convex portion 5, 55 recording portion 6, 56 recording surface 7 clamp step 8, 58 disk reference surface 9 center hole 20 turntable 21 rotation shaft 22 Magnet 23 Rotation axis reference surface 30 Cartridge 31 Upper cartridge 32 Lower cartridge 33 Shutter 33a Shutter inner surface 34 Opening 100 Information recording disk 200 Cartridge device

Claims (12)

[Claims] 1. An information recording disk having a columnar recess for accommodating a hub at the center of the surface of a disc-shaped base, and a hole for inserting a spindle formed coaxially with the base at the bottom of the recess. An information recording disk substrate, wherein an inner peripheral wall of the recess extends in a rotation axis direction of the base so as to protrude from a surface of the base. 2. The information recording disk substrate according to claim 1, wherein the extending portion is an annular rib. 3. The information recording disk substrate according to claim 1, wherein a hub is provided in the concave portion, and movement of the hub in a disk radial direction is restricted by an inner peripheral wall of the extending portion. . 4. The information recording disk substrate according to claim 3, wherein the hub is loosely fitted in the recess. 5. The apparatus according to claim 1, further comprising a projection protruding from an inner peripheral wall of the extension toward the central axis, wherein the projection restricts movement of the hub in the direction of the rotation axis of the base. 5. The information recording disk substrate according to any one of 4. 6. The information recording disk substrate according to claim 1, wherein the thickness of the base is 0.7 mm or less. 7. The method according to claim 1, wherein the distance from the lower surface of the bottom surface of the concave portion to the surface of the base is in a range of 1.3 mm to 1.6 mm. Information recording disk substrate. 8. An information recording disk manufactured using the substrate according to claim 1. Description: 9. A cartridge device comprising the information recording disk according to claim 8. 10. An information recording disk substrate comprising: a cylindrical member having a bottom portion for supporting a hub; and a disk-shaped base portion extending radially outward from an outer peripheral wall of the cylindrical member. An information recording disk substrate, wherein the base portion extends radially outward from an outer peripheral wall position lower than a top of the outer peripheral wall of the cylindrical member in the height direction of the cylindrical member. 11. An information recording disk manufactured using the substrate according to claim 10. 12. A cartridge device comprising the information recording disk according to claim 11.