JPH04351726A - Disk for information signal recording - Google Patents

Abstract

PURPOSE:To constitute the disk which can suppress the generation of the distortion, etc., of a disk substrate occurring in the use of a preadhesive and has good recording and reproducing characteristics. CONSTITUTION:This disk consists of a plate 26 fear magnetic attraction and the disk substrate 21 consisting of a synthetic resin formed with a recessed part 27 where this plate 26 is disposed. A rib 29 is formed along the peripheral edge of the recessed part 27. The plate 26 disposed in the recessed part 27 is held by thermally caulking the rib 29.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk for recording information signals, such as an optical disk or a magneto-optical disk, on which a desired information signal is recorded.

0002

2. Description of the Related Art Conventionally, discs for recording information signals, such as optical discs and magneto-optical discs, on which desired information signals are recorded have been proposed. Among this type of disks, disks that are capable of high-density recording of information signals and have extremely small diameters have been proposed. For example, a small diameter magneto-optical disk with a diameter of 64 mm or less has been proposed. The magneto-optical disk, which has such a small diameter and is capable of high-density recording, is mounted on a disk rotation drive device and rotated at high speed. Then, while rotating at high speed, a light beam emitted from the optical pickup is irradiated onto minute recording tracks provided in the signal recording layer formed on one main surface of the magneto-optical disk, and the magnetic head A desired information signal is recorded by applying an external magnetic field.

In order to accurately irradiate a light beam onto a minute recording track while being rotated at high speed,
The magneto-optical disk must be reliably integrated into the disk table of the disk rotation drive device and must be positioned and mounted with high precision.

By the way, in order to reliably integrate the magneto-optical disk into the disk table and position and mount it with high precision, a magnetic plate for magnetic attraction consisting of a metal plate or the like disposed on the side of the magneto-optical disk is attached to the disk table. A disk mounting method has been proposed in which the magneto-optical disk is mounted on a disk table by attraction using a magnet disposed on the side.

As shown in FIG. 7, a magneto-optical disk 1 used in this disk mounting method using the attraction force of a magnet is arranged so that a center hole 2 formed in the center of the disk 1 is closed. A metal plate 3 as a magnetic plate is disposed on one main surface side of the magnetic plate 1. On the other hand, a disk rotation drive device 4 for rotating the magneto-optical disk 1 has a disk table 7 integrally attached to a drive shaft 6 of a spindle motor 5, and a magnet holder 8 on the tip side of the drive shaft 6. A magnet 9 is integrally attached therebetween. Also,
At the center of the disk table 7, a centering member 11 is biased by a coil spring 12 so as to be housed in a storage portion 10 formed at the center of the disk table 7, and is moved in the axial direction of the drive shaft 6. It is installed to move forward and backward.

As shown in FIG. 7, the magneto-optical disk 1 has the center hole 2 inserted into and engaged with the centering member 11, and the periphery of the center hole 2 is supported by the disk table 7. will be placed on. At this time, the metal plate 3 is attracted by the magnet 9, so that the magneto-optical disk 1 is integrated with the disk table 7. Further, when the magneto-optical disk 1 is placed on the disk table 7, the centering member 11 moves forward and backward in the axial direction of the drive shaft 6, and the center hole 2
By entering into engagement with the drive shaft 6, the rotation center is aligned with the axis of the drive shaft 6, and the drive shaft 6 is mounted on the disk table 7.

In this way, the magneto-optical disk 1 is placed on the disk table 7 by attracting the metal plate 3 placed on the magneto-optical disk 1 with the magnet 9 and centering it using the centering member 11. As a result, the magneto-optical disk 1 is reliably integrated into the disk table 7 and mounted with high precision in positioning. Furthermore, the chucking mechanism for integrating and positioning the magneto-optical disk 1 into the disk table is also simplified. The magneto-optical disk 1 has a small diameter and is capable of high-density recording of information signals.
is stored in the cartridge 13, as shown in FIG.
The cartridge 13 is attached to the disk rotation drive device 4 while being housed in the cartridge 13.

[0008]

[Problems to be Solved by the Invention] By the way, the metal plate disposed on the magneto-optical disk that has been proposed previously is
It is bonded and attached to a disk substrate made of synthetic resin such as transparent polycarbonate resin using adhesive material such as ultraviolet curing adhesive or double-sided adhesive tape.

However, since the thermal expansion coefficients of the metal plate and the disk substrate made of synthetic resin are significantly different, when the metal plate is bonded to the disk substrate using the adhesive material described above, the environmental temperature changes and the above-mentioned problems occur. There is a problem in that when the metal plate and disk substrate repeatedly expand or contract, they may peel off. In addition, if the metal plate and disk substrate are firmly bonded so that they will not peel off even after repeated expansion or contraction, changes in the environmental temperature will cause distortion in the disk substrate, causing so-called birefringence inside the disk substrate. As a result, information signals cannot be recorded and reproduced with good recording and reproduction characteristics on the signal recording layer formed on the surface of the disk substrate.

In particular, when a metal plate is bonded to a disk substrate using an ultraviolet curable adhesive, there is a risk that birefringence may occur in the disk substrate when the adhesive is cured. Extremely large. When this ultraviolet curable adhesive is used, time is required to cure the adhesive, making it difficult to improve the productivity of magneto-optical disks.

Furthermore, since double-sided adhesive tape does not have sufficient adhesive strength, when this double-sided adhesive tape is used, it is not possible to sufficiently guarantee the reliability of bonding the metal plate to the disk substrate.

Therefore, the present invention makes it possible to attach a magnetic attraction plate to a disk substrate without using an adhesive such as an ultraviolet curing adhesive, and eliminates birefringence caused by distortion, etc. The purpose of this proposal is to provide a disk for recording information signals, which can maintain good recording and reproducing characteristics without causing any damage to the disk substrate, and which can easily attach the plate to the disk substrate, thereby improving productivity. It is what was done.

[0013]

[Means for Accomplishing the Object] In order to achieve the above-mentioned object, a disk for recording information signals according to the present invention is provided with a plate for magnetic attraction and a recess in which the plate is disposed. A disk substrate made of synthetic resin, and ribs are formed along the periphery of the recessed portion of the disk substrate, and the ribs are thermally caulked to hold the plate disposed in the recessed portion. It is.

[0014]

In the disk for recording information signals according to the present invention, the plate is held on the disk substrate by thermally caulking the ribs formed along the periphery of the recessed portion of the disk substrate. Further, by selecting the amount of caulking of the ribs, the plate is disposed within the recess of the disk substrate with a slight gap, and is movable within the recess within the range of the gap.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a disk for recording information signals according to the present invention will be described below with reference to the drawings. This embodiment shows an example in which the present invention is applied to a magneto-optical disk, and as shown in FIG. It has a disk substrate 21 which is formed into a disk shape. One main surface 21 of this disk substrate 21
On the a side, an information signal recording layer in which a desired information signal is recorded is deposited. Then, the disk substrate 21
is one main surface 21a on which the information signal recording layer is deposited.
The other main surface 21b facing the main surface 21b is used as a signal writing/reading surface, and information signals are recorded and reproduced by irradiating the signal recording layer with a light beam from this signal writing/reading surface.

[0016] In the center of the disk substrate 21,
As shown in FIGS. 1 and 2, a center hole 22 is bored into which a centering member 11 disposed at the center of the disk table 7 constituting the disk rotation drive device 4 described above engages. Further, on the other main surface side of the disk substrate 21, a cylindrical centering member engaging portion 23 surrounding the center hole 22 is protruded as shown in FIG. This centering member engaging portion 23 makes the depth of the center hole 22 bored in the thin magneto-optical disk 21 deep, and ensures a sufficient amount of engagement of the centering member 11 with this center hole 22. It is designed for the purpose of

Further, on the other main surface side of the disk substrate 21, there is a disk regulating protrusion that is provided to surround the disk table insertion hole opened in the cartridge when the magneto-optical disk 21 is housed in the cartridge. As shown in FIG. 2, a position regulating protrusion 24 for regulating the storage position of the magneto-optical disk 21 in the cartridge is protruded so as to surround the centering member engaging portion 23. The area surface surrounded by the centering member engaging portion 23 and the position regulating protrusion 24 is a smooth surface, and when the magneto-optical disk 21 is placed on the disk table 7, it is supported by the disk table 7. This serves as a mounting reference surface 25.

[0018] On one main surface side of the disk substrate 21, in the center corresponding to the center hole 22, there is a
The disk table 7 is arranged so as to surround this center hole 22.
A recess 27 for storing a plate is formed in which a metal plate 26, which is a plate made of a magnetic material that is attracted by the magnet 9 disposed on the side, is stored. This recess 27 is formed to have a diameter R2 slightly larger than the outer diameter R1 of the metal plate 26 so that a slight gap is created between the metal plate 26 and the metal plate 26 when the metal plate 26 is stored here. . Further, a ring-shaped protrusion 28 is protruded from the periphery of the recess 27 in order to ensure a sufficient depth to accommodate the metal plate 26 of a predetermined thickness. Then, the concave portion 27 is made to protrude from the end surface of the protruding portion 28.
A plurality of ribs 29 are formed to hold the metal plate 26 housed in the recess 27. In this embodiment, six ribs 29 are formed at equal intervals, as shown in FIG.

Note that a stepped portion 30 is formed on the inner periphery of the bottom side of the recessed portion 27. This stepped portion 30 functions as a relief portion for cutting the runner portion that is generated when the disk substrate 21 is molded. That is, the step portion 30
This is to prevent the forming precision of the center hole 22 and the recess 27 from being affected when cutting the runner portion.

The rib 29 is heated by applying ultrasonic waves and is crushed inwardly into the recess 27, so that the crushed tip 29a causes the rib 29 to be heated as shown in FIGS. 3 and 4. As shown in FIG. 2, the periphery of the metal plate 26 housed in the recess 27 is caulked to hold the metal plate 26 in the recess 27. Note that the ribs 29 may be caulked not only by ultrasonic waves but also by a heating method using a heating iron or the like. That is, any method may be used as long as the tip of the rib 29 can be thermally caulked.

By the way, the rib 29 has a tip end 29a.
The metal plate 26 in the recess 27 is crushed so as not to come into contact with the metal plate 26 under pressure. That is, the rib 29 has a slight gap D1 between the metal plate 26 and the tip 29a of the rib 29 that caulks the metal plate 26, as shown in FIG.
It is crushed so that .

Furthermore, as described above, since the recess 26 is formed with a diameter R2 slightly larger than the outer diameter R1 of the metal plate 26 accommodated therein, the metal plate 26 is They are loosely fitted and held in the recess 27 with slight gaps D1 and D2, respectively. As a result, even if the disk substrate 21 and the metal plate 26, which have significantly different coefficients of thermal expansion, repeatedly expand or contract in response to changes in environmental temperature, the difference in expansion or contraction resulting from the difference in the coefficients of thermal expansion will be , are absorbed by the gaps D1 and D2, and are prevented from influencing each other, thereby preventing distortion or the like from occurring in the disk substrate 21. As a result, birefringence does not occur in the disk substrate 21.

The magneto-optical disk 20 with the metal plate 26 attached to the disk substrate 21 as described above is housed in a cartridge in the same way as the conventional magneto-optical disk 1 described above, and remains housed in the cartridge. The disk drive device 4 is mounted on the disk table 7 of the disk rotation drive device 4.

In the above-mentioned embodiment, a plurality of ribs 29 are provided separately and independently for caulking and holding the metal plate 26 housed in the recess 27, but as shown in FIG. , it may be formed into a series of rings surrounding the periphery of the recess 27. And ring-shaped rib 2
The distal end side of the recess 9 can be crushed over the entire circumference, and the crushed distal end portion can hold the metal plate 26 housed in the recess 27.

In the above-described embodiment, the present invention is applied to a magneto-optical disk. However, the present invention can be widely applied to disks such as optical disks in which a magnetic attraction plate is arranged on a disk substrate made of synthetic resin. This makes it possible to achieve the same effects as the magneto-optical disk described above.

[0026]

Effects of the Invention As described above, the information signal recording disk according to the present invention has magnetic attraction by thermally caulking the ribs formed along the periphery of the concave portion of the disk substrate made of synthetic resin. Since the plate for magnetic attraction is held on the disk substrate, not only can it eliminate all the problems that arise from using adhesives such as ultraviolet curing adhesives, but also the disk substrate made of synthetic resin and the magnetic attraction plate can be used together. It is possible to prevent distortion of the disk substrate caused by the difference in the coefficient of thermal expansion of the plates, and to maintain good recording and reproducing characteristics without causing birefringence of the disk substrate due to this distortion.

Furthermore, since the magnetic attraction plate is held by thermal caulking of the ribs, it can be easily attached to the disk substrate, and productivity can be improved.

Furthermore, since the plate is attached to the disk substrate without using adhesive, it does not peel off from the disk substrate due to insufficient adhesive strength or deterioration of the adhesive, and has sufficient mounting strength. can be maintained.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a magneto-optical disk according to the present invention.

FIG. 2 is an enlarged sectional view taken along the line A-AS in FIG. 1 of a disk substrate constituting the magneto-optical disk according to the present invention.

FIG. 3 is a perspective view of a magneto-optical disk showing a state in which a metal plate is attached to a disk substrate.

FIG. 4 is an enlarged sectional view of the magneto-optical disk showing a state in which a metal plate is attached to a disk substrate. It is.

FIG. 5 is a partially enlarged sectional view of the magneto-optical disk showing a state in which a metal plate is attached to the disk substrate. It is.

FIG. 6 is a perspective view showing another example of a disk substrate constituting the disk according to the present invention.

FIG. 7 is a sectional view showing a state in which a conventional magneto-optical disk is mounted on a disk table of a disk rotation drive device.

[Explanation of symbols]

20... Magneto-optical disk 21...Disk board 22...center hole 26...metal plate 27... recess 29...Rib

Claims (1)

[Claims] 1. A disk substrate made of synthetic resin, comprising a plate for magnetic attraction and a recess in which the plate is disposed, a rib being formed along the periphery of the recess of the disk substrate, and A disk for recording information signals is formed by thermally caulking this rib to hold a plate disposed in the recess. .