JPH07105570A - Optical disk - Google Patents

Abstract

PURPOSE:To suppress dusting property and to use an optical disk for a long time by an autochanger or the like by chamfering the edge part of the optical disk so that the length in the thickness direction of the disk is a specified value or more in the contact part between the edge part of the disk and the inner surface of a cartridge. CONSTITUTION:This optical disk has an air-sandwich structure consisting of substrates 21 of both sides, recording layers 22, spacer 23, and surface protective layers 27, and further, an air layer 24 is formed. This optical disk is housed and can be rotated in a cartridge made of synthetic resin such as polycarbonate resin and ABS resin. The end face 28 of the edge part of the disk is chamfered by machining corners of the edge of the substrate so that the length 11 in the thickness direction of the optical disk is >=1.4mm. Thus, dusting due to contact between the inner surface of the cartridge with the edge part of an optical disk when optical disks are exchanged can be suppressed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an optical disc. More specifically, the present invention relates to an optical disc that has an improved shape of the end face of the substrate and has little dust generation.

[0002]

2. Description of the Related Art In recent years, optical discs on which information is recorded / reproduced by irradiating a laser beam have a large storage capacity and can be easily carried. It's starting. The main applications of optical discs are external memory of computers and image files. In these applications, a large storage capacity is required, and a jukebox that can store tens of optical disks is used. The jukebox usually has a plurality of optical disk drives built-in, and is equipped with a mechanism for automatically taking out the optical disks in the storage box by an autochanger and setting them in the optical disk drive.

[0003]

The frequency of exchanging (loading / unloading) optical disks by the autochanger in the above-mentioned jukebox may be several sheets per minute. Generally, an optical disc is used by being put in a case (cartridge) made of plastic, and dust is generated from the case or the optical disc when the inner surface of the case and the peripheral edge of the optical disc come into contact with each other and are rubbed during a replacement operation. The generated dust accumulates on the surface of the optical disc or adheres to the inside of the case, which may cause a problem such as the stop of the autochanger or the occurrence of a recording error or a reproduction error.

[0004]

In view of the above problems of the prior art, the inventors of the present invention have made earnest studies to prevent dust generation due to contact between the end surface of the optical disk substrate and the inner surface of the cartridge. Finding that the above problems can be solved by setting the shape of the end face to a specific shape,
The present invention has been completed.

That is, the gist of the present invention is, in an optical disc having a recording layer for recording and reproducing optical information on a transparent substrate, in the thickness direction of the optical disc at the contact portion between the peripheral portion of the optical disc and the inner surface of the cartridge. Is 1.
An optical disk is characterized in that the peripheral edge of the optical disk is chamfered to be 4 mm or more. An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a disk cartridge (a cartridge in which a disk is housed). In the drawing, 1 has a recording area 2, an outer peripheral non-recording area 3 and an inner peripheral non-recording area 4. A magnetic metal hub 5a, 5b for magnet chucking is provided in the center. As the disc 1, for example, an optical disc in which an information signal recording layer is provided on a disc substrate made of polycarbonate resin is preferably used.

From the structure of the optical disk, there are an air sandwich structure method as shown in FIG. 2 and a whole surface contact bonding method as shown in FIG. The present invention can be applied to any of these structures. In the figure, 21 is a substrate, 22 is a recording layer, 23 is a spacer, 24 is an air layer, 25 is an adhesive layer, and 27 is a surface protective layer (overcoat layer). Reference numeral 6 denotes a disk cartridge for rotatably housing the disk 1 therein, which is formed by injection molding a synthetic resin having good mechanical properties and sufficient mechanical strength, such as polycarbonate resin or ABS resin. The disc cartridge 6 is composed of an upper half 7 and a lower half 8, and is formed by abutting the discs 1 with each other in a state where the discs 1 are housed and screwing them together. Usually, disk receiving ribs 11 and 12 are formed on the inner surfaces surrounding the insertion openings 9 and 10 of the upper half 7 and the lower half 8 of the cartridge 6 so as to correspond to the non-signal recording area 4 on the inner peripheral side of the disk 1. , Are provided circumferentially.

In the present invention, the recording layer 2 is formed on the disc substrate.
2 and the peripheral portion of the optical disk substrate shown in FIG. 3 in which the recording layers 22 of the two substrates are placed inside each other and formed by the air sandwich method or the entire surface adhesion bonding method after forming the surface protection layer 27 and the surface protection layer 27. The contact surface with the inner surface of the disk cartridge 6, that is, the end surface 28 of the peripheral edge of the optical disk
The edge portion of the optical disk substrate is cut so that the length l ₁ of the optical disk in the thickness direction (vertical direction) is 1.4 mm or more, preferably 1.4 to 2.4 mm. It is characterized by having a chamfered structure. If the vertical length l _{1 of the} optical disk end surface 28 is less than the above range, the effect of suppressing dust generation due to contact between the inner surface of the cartridge 6 and the optical disk end surface is significantly reduced.
Moreover, the error rate remarkably increases, which is not preferable.

In the present invention, a resin substrate made of polycarbonate resin, acrylic resin, polystyrene resin, polymethylmethacrylate resin or the like is used as the substrate 1.
As the recording layer 21, any layer structure generally used for publicly known optical recording can be used. For example, Al,
A read-only recording layer made of a metal having a high reflectance such as Au, and a write-once recording layer made of a metal having a low melting point such as Te.
Also, for example, TbFe, TbFeCo, TbCo, Dy
Amorphous magnetic alloys of rare earths such as FeCo and transition metals, Mn
An example of the magneto-optical recording layer is a polycrystalline perpendicular magnetization film such as Bi or MnCuBi. A single layer may be used as the magneto-optical recording layer, or a single layer such as GdTbFe / TbFe may be used.
Recording layers of more layers may be stacked.

Normally, in the case of the write-once type (drilling type), as shown in FIG. 2, an air sandwich type in which a spacer 23 is interposed so as to form an air layer 24, and in the case of the magneto-optical recording type, As shown in FIG. 3, the adhesive layer 25 is used as a bonding type in which two substrates are bonded together. The present invention is applicable to any type of medium. Various curable resins such as a photocurable resin, a thermosetting resin, and a moisture curable resin are used as a curable resin which is a base of the surface protective layer 27, and an ultraviolet curable resin is preferably used. Examples of the ultraviolet curable resin include acrylic resins, epoxy resins and urethane resins.

[0011]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 A substrate having a hole with a diameter of 15 mm in the center of 130 mm,
A circular flat plate-shaped polycarbonate injection-molded substrate with a guide groove having a plate thickness of 1.2 mm was used to form a film having the following layer structure as a magneto-optical recording medium on the substrate by a continuous sputtering device.

[Equation 1] SiN _x (750Å) / TbFeCo (300Å) / AlSi (400
Å) / SiN _x (350Å) A hot melt adhesive was applied to the side of the recording film on the recording film of this substrate with a roll coater at a thickness of 50 μm. The adhesive used was Cemedine HM-458 (trade name, manufactured by Cemedine). Next, using a press machine, 2
The coated surfaces of the discs were set so that they faced each other, and they were pressed against each other so as to be bonded to each other.

The peripheral portion of the obtained optical disc is shown in FIG.
As described above, it was cut by a cutting machine using a cutting tool. Got
Line contact between the end surface of the optical disk of the present invention and the inner surface of the cartridge
Length (l ₁) Was 2.3 mm. This is NKK
Load using an optical auto changer manufactured by
After performing unloading test 30,000 times, appearance inspection
No dust was found in the inspection. Also, Sony
The number of defects before and after the test with the company's magneto-optical disk drive
When I measured (byte error rate), there was no increase
It was The results are shown in Table 1.

Example 2 An end face length (l ₁ ) of 1.4 mm was prepared in the same manner as in Example 1.
The same procedure was performed except that the cutting was performed so that The results are shown in Table 1.

Comparative Example 1 A sample was prepared in the same manner as in Example 1 and cut so that the end face length was 1.2 mm. After performing the same test as in Example 1 30,000 times and then performing an appearance inspection, the cartridge case was scraped and dust was generated. In addition, the byte error rate before and after the test was 0.
It increased from 5 × 10 ^-5 to 8 × 10 ^-5 . The results are shown in Table 1.

[0016]

[Table 1]

Comparative Example 2 It was prepared in the same manner as in Example 1 and was cut so that the end face shape was an arc shape. The end surface of the optical disk and the inner surface of the cartridge are in point contact (l ₁ is 0.2 mm or less). When the same test as in Example 1 was performed 30,000 times and the appearance was inspected, much dust was generated from the cartridge case. When the byte error rate before and after the test was measured with the Sony magneto-optical disk drive, it was found to increase from 0.7 × 10 ⁻⁵ to 2 × 10 ⁻⁴ .

[0018]

According to the present invention, it is possible to provide an optical disk with little dust generation, and to provide an optical disk that does not cause a problem even if it is used for a long time by an autochanger or the like in a jukebox or the like.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a disk cartridge.

FIG. 2 is a vertical sectional view of an example of an optical disc.

FIG. 3 is a vertical sectional view of an example of an optical disc.

[Explanation of symbols]

 1 disc 6 cartridge 28 optical disc end face

Claims (1)

[Claims] 1. In an optical disc having a recording layer for optically recording and reproducing optical information on a transparent substrate, the contact portion between the peripheral edge of the optical disc and the inner surface of the cartridge has a length in the thickness direction of the optical disc of 1.4 mm. An optical disk characterized in that the peripheral portion of the optical disk is chamfered as described above.