JPH0594642A - Optical disk - Google Patents

Abstract

PURPOSE:To increase the ratio to be occupied by the signal area of a disk surface by forming a signal recording layer which can make optical recording and/or reproducing on a substrate and providing identification marks on the outer peripheral surface thereof. CONSTITUTION:The recording layer 2 is provided by a sputtering method on the disk-shaped transparent substrate 1. The substrate 1 is formed of an acrylic resin or epoxy resin. Guide grooves or number code pits (not shown in Fig.) having a depth of about 1/4 the wavelength of the laser to be used for reproducing are provided in the part corresponding to the signal area on the side to be provided with a recording part 2 on the surface of the substrate 1. A disk-shaped disk hub 4 is mounted to the central part of the substrate 1. Thus hub 4 is magnetically attracted to a disk table and is rotationally operated together with a disk table. Since the identification marks are provided on the outer peripheral surface 7, there is no need for providing a lot number on the disk surface and, therefore, the ratio to be occupied by the signal area of the disk surface is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc for recording / reproducing information by irradiating a laser beam.

[0002]

2. Description of the Related Art Conventionally, as optical discs for recording / reproducing information by irradiating laser light, magneto-optical discs, various write-once optical discs, rewritable optical discs, digital audio discs (so-called compact discs), optical video Various media such as disks (so-called laser disks) have been put into practical use.

In such an optical disc, a signal recording layer capable of optical recording and / or reproduction is usually formed on a disk-shaped substrate made of polycarbonate or the like, and the signal recording layer is further protected. The protective film is formed. Then, the signal recording layer is irradiated with laser light from the signal reading surface side (usually the substrate surface side), and the reflectance or phase of the pit portion formed in this signal recording layer and the portion in which the pit is not formed are measured. The signal is read out by detecting the difference.

The structure of such an optical disk will be described in more detail by taking a magneto-optical disk as an example. As shown in FIG. 4, in the magneto-optical disk, a magnetic field is formed on the turntable of the recording / reproducing apparatus at the center of the substrate 40. A disk hub 41 that holds the optical disk on the turntable by being chucked is attached. For this reason, the signal recording layer is formed in a portion excluding the portion to which the disc hub is attached and the peripheral portion thereof, and prevents the outer peripheral end surface of the signal recording layer from coming into contact with the outside and corroding. Therefore, the film is formed so as to slightly retract from the outer peripheral edge of the disk substrate. Therefore, in the optical disc,
Around the disk hub 41 attached to the central portion becomes a transparent area 42 where no signal recording layer is formed, and further,
The surrounding area becomes the signal recording layer area 43, and the portion extending from the outer periphery of the signal recording layer area 43 to the outer peripheral edge of the substrate is the guide area 4.
It becomes 4. Here, in the formed signal recording layer, the film thickness becomes unstable at the outer peripheral edge and the inner peripheral edge due to the film forming technique, and the characteristics vary. Therefore, in designing an optical disc, the inner peripheral edge portion and the outer peripheral edge portion of the signal recording layer area 43 are not used for recording / reproducing as the mirror portions 45a and 45b, and the recording layer excluding the mirror portions 45a and 45b is used. The area is used as a signal area 46 for recording and reproduction. On the surface of the substrate corresponding to the signal area 46 on the signal recording layer side, there are formed guide grooves and address code pits that are formed in a substantially concentric shape and are formed in a spiral shape. Signals can be detected by servos and address codes.

By the way, in the manufacture of products,
In order to perform quality control, batch numbers are added to the quantity handled at one time during work or inspection. This is also true for optical discs. Such lot numbers are used in the inner peripheral mirror portion 45a for 5.25-inch optical discs, and the stamper holder groove in the transparent area 42 for 3.5-inch optical discs. The space between 47 and the hub 41 is printed by inkjet. That is, in each case, the lot number is attached by utilizing the inner peripheral portion which is not used as the signal area on the disc surface.

[0006]

On the other hand, in the field of optical discs, 5.25-inch size and 3.5-inch size ones have already been put into practical use as products, but studies are being made to obtain smaller optical discs. The so-called mini disk having a diameter of about 6 mm is being developed as a small-sized magneto-optical disk for practical use. In the case of small optical discs, it is important to record as much information as possible on the disc surface with a small area, and by devising the method of forming the recording magnetic layer, etc., the mirror and transparent parts should be kept as small as possible. The design is made with the priority of securing a space that can be used as an area.

Therefore, when the size of the optical disc is reduced, the mirror area and the transparent area which are not used as the signal area are extremely narrowed, and it is difficult to attach a lot number to this portion. In the case of mass production as a product, quality control by lot number should always be performed, and in order to commercialize a small optical disc, it is possible to attach lot numbers without reducing the amount of recorded information. There is a need to develop means that can.

Therefore, the present invention has been proposed in view of such a conventional situation, and it is an object of the present invention to provide an optical disk in which a sufficient signal area space can be secured even when a lock number is added.

[0009]

In order to achieve the above object, the optical disc of the present invention comprises a signal recording layer capable of optical recording and / or reproduction formed on a substrate, and has an outer peripheral surface. It is characterized by being provided with an identification mark.

[0010]

When the lot number is attached to the disc surface of the optical disc, the portion to which the lot number is attached cannot be used as a signal area, and the amount of recorded information is reduced accordingly. On the other hand, if an identification mark is provided on the outer peripheral surface of the optical disc, the lot number can be known, and it is not necessary to provide the lot number on the disc surface. Therefore, the space that can be used as a signal area on the disk surface becomes large, and the amount of recorded information increases.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the optical disc of the present embodiment is provided with a signal recording layer 2 formed by sputtering or the like on a disk-shaped transparent substrate 1, and further the signal recording layer 2 is provided.
The protective film 3 is formed so as to cover the surface of the.

The material of the transparent substrate 1 may be any substrate material normally used for optical discs. In addition to plastic materials such as acrylic resin, polycarbonate resin, polyolefin resin and epoxy resin,
Glass etc. are also used. It should be noted that, in the portion of the surface of the transparent substrate 1 corresponding to the signal area on the side where the recording portion is provided, the wavelength of the laser beam used for reproduction is usually about
A guide groove, an address code pit, and the like having a depth of one-half (not shown) are provided.

A disk-shaped disk hub 4 is attached to the center of the transparent substrate 1. This disc hub 4
Is magnetically attracted to a disk table fixed to the tip of a spindle shaft of a recording / reproducing device (not shown), and is rotated together with the disk table. Therefore, at least the surface 4a sucked and held on the disk table of the disk hub 4 is made of a magnetic material such as metal. Also, in the center of the disc hub,
A center hole 8 is formed so that the position of the optical disc with respect to the disc table is regulated. The material of the portion other than the surface of the disc hub that is suction-held on the disc table is not particularly limited, and a plastic material such as polycarbonate is suitable in consideration of weight reduction. ..

Further, on the surface of the transparent substrate 1, the signal recording layer 2 is formed on the entire surface except the peripheral portion and the outer peripheral edge of the disk hub 4. The signal recording layer 2 is not particularly limited and may be arbitrarily selected according to the application. For example, a digital audio disc or a so-called CD-R
In OM or the like, a metal reflective film of Al or the like is formed on the disk substrate on which the concavo-convex pattern is transferred. Magneto-optical characteristics (Kerr effect and Faraday effect) in magneto-optical disks
A perpendicularly magnetized film having is formed. In addition, it can be applied to an optical disc having a recording layer of a low melting point metal thin film, a phase change film, a film containing an organic dye, or the like.

Further, a protective film 3 made of an ultraviolet curable resin or the like is formed so as to cover the surface of the signal recording layer 2. The protective film 3 is provided to protect the signal recording layer 2 from impact and corrosion caused by contact with an external environment, and is formed by curing an ultraviolet curable resin applied by a spin coater, for example. Is.
The material of the protective film is not particularly limited, but any material can be used as long as it can be applied by a spin coater and then cured to form a film having sufficient strength.

In the above-mentioned optical disc, the lot number for manufacturing control as shown in FIG. 2 is a bar code on the outer peripheral surface 6 of the disc on which the signal recording layer 2 and the ultraviolet curing resin layer 3 are thus formed on the substrate. 21 is attached. If the lot number is attached to the outer peripheral surface 6 of the disc, a space for attaching the lot number to the disc surface is not needed, and therefore a large signal area can be provided on the disc surface. Therefore, the amount of recorded information per disc can be increased, which is also advantageous for downsizing the optical disc.

The bar code 21 can be printed on the outer peripheral surface 6 of the disk by, for example, the ink jet method, the tacho printing method or the like. In order to attach the bar code 21 by the tacho printing method, a predetermined bar code pattern is formed on a flexible plate material, and the plate material on which this pattern is formed is used for screen printing or transfer. A bar code pattern is printed on the outer peripheral surface 6 of the disk by.

On the other hand, the above-mentioned ink jet method is a method in which ejection of liquid ink is controlled by pressure or an electric field for recording. Bar code 21 by inkjet method
3 is printed by directly spraying ink onto the disk outer peripheral surface 6 with an inkjet printer having the above control function.
If the disc supporting device as shown in FIG. 2 is used, the barcode 21 can be printed without contaminating the portion other than the disc outer peripheral surface 6 with the ink.

That is, the above-mentioned disc supporting device supports the optical disc 7 by sandwiching the optical disc 7 between the upper protection jig 31 and the lower protection jig 32. The upper protection jig 31 and the lower protection jig 3
2 is formed as a disc body having convex portions 31a, 32a on the ring along the outer peripheral edge. The outer diameter of the convex portion is substantially the same as the outer diameter of the optical disc, and the width thereof is substantially the same as the width of the optical disc guide portion 36. When the optical disc is sandwiched, the convex portions 31a and 32a are formed.
Is designed so that it does not touch the signal area.

At the center of the lower protection jig 32, there is provided a center pin 33 through which the center hole 8 of the sandwiched optical disk 7 is inserted. By inserting the center hole 8 into this center pin 33, , The above protection jig 3
The position of the optical disk 7 with respect to 1, 32 is restricted. On the other hand, at the center of the lower protection jig 32, a tubular fitting portion 34 into which the tip of the center pin 32 is fitted is provided, and the tip portion of the center pin 33 is fitted into this fitting portion 34. By being inserted, the convex portion 31a of the upper protection jig 31, the lower protection jig 32, and the convex portion 32a are surely aligned with each other with the guide portion 36 of the optical disc 7 interposed therebetween.

When the optical disk is supported by the disk supporting device having the above structure, the disk surface 9 of the optical disk is protected by the protection jigs 31 and 32, so that the ink ejected from the ink jet printer 35 adheres to a portion other than the outer peripheral surface. There is nothing to do. Therefore, when the bar code is attached, the signal area is not contaminated, and the predetermined bar code can be reliably printed only on the outer peripheral surface 6.

Further, in order to read the lot number from the bar code attached to the outer peripheral surface 6 as described above, for example, while rotating the optical disk, light is emitted from the light source to the outer peripheral surface provided with the bar code, The reflected light at this time is CC
Detect by D. Then, if the detected bar code information is converted into a number, the lot number of the product can be easily read.

[0024]

As is apparent from the above description, in the optical disc of the present invention, since the outer peripheral surface is provided with the identification mark, there is no need for a space for providing the lot number on the surface of the disc. Therefore, according to the present invention, it is possible to increase the ratio of the signal area on the disk surface, and it is possible to obtain a sufficiently practical amount of recorded information even when the optical disk is downsized.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an optical disc.

FIG. 2 is a schematic perspective view showing an identification mark attached to the outer peripheral surface of the optical disc.

FIG. 3 is a schematic perspective view showing a configuration of a disk support device used when an identification mark is attached by an inkjet method.

FIG. 4 is a main part schematic plan view showing an example of the specification design of an optical disc.

[Explanation of symbols]

 1 ... Transparent substrate 2 ... Signal recording layer 3 ... Protective layer 4 ... Disk hub 21 ... Bar code

[Procedure amendment]

[Submission date] May 20, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

On the other hand, in the field of optical discs, 5.25-inch size and 3.5-inch size ones have already been put into practical use as products, but studies are being made to obtain smaller optical discs. Is being promoted. For example, as a small magneto-optical disk, the diameter is about 64 mm.
Every time the so-called mini-disk has is being developed toward the practical use. In the case of a small optical disc, it is important to record as much information as possible on the disc surface with a small area. By devising the method of forming the recording magnetic layer,
The design is made with priority given to keeping the space that can be used as the signal area by keeping the mirror and transparent parts as small as possible.

Claims (1)

[Claims] 1. An optical disc comprising a signal recording layer capable of optical recording and / or reproduction formed on a substrate, and an identification mark provided on the outer peripheral surface thereof.