JP2001035006A - Optical disk and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the incidence plane of an optical disk on which light for reading and writing is incident from the leaving of a fingerprint and scuffing by disposing protrusions that protect the information recording region on the incidence plane. SOLUTION: A large number of fine protrusions 7 are disposed on an incidence plane 6 on which light for reading and writing is incident as a face of a transparent substrate 1 opposite to the rugged face 2a. The protrusions 7 are disposed on at least the information recording surface and have such a size as not to shield radiated laser light and as to protect the incidence plane from the leaving of a fingerprint and scuffing. When the resulting optical disk is taken by hand and a finger touches the incidence plane 6 of the optical disk, the finger 8 comes in contact with the fine protrusions 7 and the incidence plane 6 is protected from the leaving of a fingerprint and scuffing. Even when the optical disk is put on a desk, the fine protrusions 7 come in contact with the desk and the incidence plane 6 is protected from scuffing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optically readable and writable recording medium, specifically, a CD and a CD-ROM.
R, DVD-ROM, DVD-RAM, and DVD-R.

[0002]

2. Description of the Related Art In recent years, information devices such as personal computers, DVDs, etc.
With the development of video equipment such as players, various demands have been made on optically readable and writable recording media such as optical disks as information media.

Hereinafter, description will be made based on an optical disk as a recording medium. The structure of a conventional optical disk will be described with reference to FIG.

[0004] One surface of the transparent substrate 51 is provided with irregularities, and the irregular surface 52 is sputtered with an aluminum thin film 53 to form an information recording surface. Then, the adhesive 5 is applied to the sputtered aluminum thin film 53.
5 and another transparent substrate 54 are bonded to each other to form an optical disk.

Here, the unevenness has a depth of 1/4 of the wavelength of light.

The information recorded on the optical disk is a laser beam 56.
Is condensed by the lens 57 on the uneven surface 52 through the light incident surface 58 of the transparent substrate 51, and is read out by light and dark due to interference of light reflected on the uneven surface 52.

[0007]

Generally, an optical disc is required to read or write information with high reliability (in the case of CD-R, DVD-RAM, DVD-R). However, if there is a fingerprint or a scratch (especially in the circumferential direction) on the light incident slope 58 of the optical disk, the laser light 56 is irregularly reflected or absorbed and does not reach the uneven surface 52, so that information cannot be read and written accurately. . Here, FIG. 7 shows an example of the state of the scratch on the inclined surface of the optical disk, and there are a small scratch 59, a circumferential scratch 60, and a radial scratch 61 on the disk (broken line (a)).
Indicates the circumferential direction, and the broken line (b) indicates the radial direction).

[0008] In particular, with the spread of optical disks, various people from small children to the elderly use the disks, and the handling of the disks is also messy, and the influence of fingerprints and minute scratches is coming out. Is also a fact. Further, as the amount of information increases, even finer scratches have a greater effect on the disc.

[0009] Small scratches and radial scratches can be corrected by giving information redundancy.
In particular, it is difficult to correct errors such as restoration of information for circumferential scratches.

An object of the present invention is to solve the above-mentioned problems of the prior art and to improve the reliability of reading and writing information.

[0011]

In order to achieve the above object, the present invention provides a projection for protecting an information recording area on an inclined surface of an optical disk on which light beams for reading and writing are incident. Prevent fingerprints or scratches on the bottom of the slope.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the embodiments, the same components will be described with the same reference numerals.

In the present embodiment, the information recording area is an area on the information recording surface where information can be recorded, the projections are minute projections or linear projections, and the protective layer is an adhesive, another transparent substrate, a protective coating ( This is described in FIG. 11).

(Embodiment 1) FIG. 1 shows a cross section of an optical disk according to an embodiment of the present invention.
The transparent substrate 1 has unevenness 2 with a depth of 1/4 of the wavelength of light on one side.
The aluminum thin film 3 is sputtered on the uneven surface 2a to form an information recording surface.
Another transparent substrate 5 is bonded to the aluminum thin film 3 via an adhesive 4. Here, the transparent substrate is usually made of a polycarbonate resin. The substrate thickness here is 6 [m
m]. The adhesive used was an ultraviolet-curable acrylic resin and had a thickness of 40 to 60 [μm]. Further, a gold film may be used instead of the aluminum thin film.

A large number of fine projections 7 are provided on an inclined surface 6 for reading and writing light, which is a surface opposite to the uneven surface 2a of the transparent substrate 1.

Here, in order to eliminate the influence of scratches, fingerprints, etc., the projections need to be arranged at least on the surface on which information is recorded, and have a size that does not block the laser beam to be irradiated. In order to prevent scratches or fingerprints on the incline, it has a size. Specifically, the size of the protrusion is preferably around 0.2 mm, and the height is preferably in the range of about 0.1 to 0.3 mm, but it is appropriately used depending on how to give information.

FIG. 3 shows the relationship between the microprojection 7 and the finger 8 when the optical disk is held by a hand or the like.
The finger 8 comes into contact with the minute projection 7 to prevent a fingerprint or a scratch from being attached to the inclined surface 6 of the light (especially, a scratch or a fingerprint is attached to the bottom surface 22 of the entered slope 6).

Further, even if an optical disk is placed on a desk, for example, and the desk and the disk come into contact with each other, they come into contact with the minute projections 7, so that the light incident surface 6 can be prevented from being damaged.

Next, the embodiment will be described in detail. First, in this embodiment, the laser beam for reading and writing actually has a condensing diameter of Φ0.2 [m
m], irradiation diameter Φ0.15 [mm], laser wavelength 65
The light having a wavelength of 0 [nm] was used and was incident substantially perpendicularly to the entrance slope.

The distance between the protrusions is 20 mm on the same circumference.
It is preferable to provide the above. This is because if the distance between the protrusions is short, even if the protrusion is recognized as an error such as a scratch or dust when reading or writing with a laser beam, it is possible to correct the error due to the recognition by error correction. Because.

It is desirable that the projection is provided from the inner peripheral side (shown in FIG. 2A) of the information recording surface of the disk. This is necessary from the viewpoint of protection of the recorded portion, since the recording of the disc is performed from the inner peripheral side to the outer peripheral side (shown in FIG. 2B).

In general, when a disc is to be gripped, a fingerprint or a scratch is easily formed on the outer peripheral side because the outer peripheral side is held by a finger. Therefore, providing a projection on the outer peripheral side has another technical significance.

Further, in order to further improve the safety and reliability, as shown in FIG. 2, a large number of the fine projections 7 are uniformly provided on the inclined surface of the light in the area where the information indicated by the symbols A and B is recorded. Is desirable.

As a specific example, the height of the protrusions is about 0.2 mm, and the space between the protrusions needs to be on the same circumference, that is, about 20 (mm) on the same track, and 5 between adjacent circumferences.
(Mm).

The shape of the projection is not particularly limited, such as a circle. However, as shown in FIG. 8, a projection having a flat top 62 and a trapezoidal cross section (tapered side 63) is preferable. This is less likely to be crushed when pressed by the finger 64 as shown in FIG. 9B than in the case of a cone as shown in FIG. 9 (FIG. 9A), and the pressing force acting on the projection is made uniform. Can be made, so that scratches and fingerprints are less likely to be formed. Further, by forming the protrusions into a tapered shape, when the protrusions are formed by a mold, the protrusions are easily released, and minute protrusions can be formed with high accuracy. (If it is difficult to release the mold here, the protrusion may be removed or the accuracy may be deteriorated and the original function may not be achieved.) Further, the color of the minute protrusion is as shown in FIG. In the reading, the irradiation light 30 such as laser light is reflected on the projection surface 31 and affects the other surface 32 of the disk.
In order to prevent an error in the writing process, a color that absorbs light without being reflected by the surface is used. Although black is used in this embodiment, any color that absorbs light, such as brown, may be used.

(Embodiment 2) FIG. 4 shows a light incident surface of an optical disk whose surface is protected in the same manner as described in Embodiment 1. In the first embodiment, the minute protrusions 7 are provided on the inclined surface 6. However, in the present embodiment, the linear minute protrusions (hereinafter, referred to as linear protrusions) 9 formed in a radial shape are formed on the inclined surface 6.
Provided.

In this embodiment, when the inclined surface of the optical disk comes into contact with a finger or other object, the surface becomes line contact, so that the surface pressure can be kept low even with a large force, and the deformation of the projection is small. Therefore, fingerprints and scratches are less likely to be formed.

Here, the linear projections are arranged in a staggered pattern as shown in the figure.

As shown in the drawing, auxiliary projections (9a, 9b) are arranged on the outside so that the intervals are substantially constant inside and outside the disk. This makes it possible to protect the entire recording surface.

FIG. 5 shows a mold device for simultaneously forming the linear projections 9 shown in FIG. 4 on the transparent substrate 1. A stamper 12 having an unevenness of 1/4 of the wavelength of light is attached to a surface of a cavity 11 of an upper mold 10 having a sprue for injecting a substrate resin by an outer peripheral ring 13. Radial concave portions 15 are formed on the surface of the lower mold 14. The substrate 1 is a cavity 1 surrounded by an upper mold 10, a stamper 12, an outer ring 13, and a lower mold 14.
1. A resin (not shown) heated and melted is poured into 1 and cooled. In this way, the radial minute projections 9 can be formed at once by resin molding in a mold, and the interval, size, and the like of the minute projections can be made suitable in advance with a simple configuration with high accuracy. . In addition, the shape of one microprojection can be made uniform, and even when the flow of resin becomes poor during molding, the microprojection has such a uniform cross-sectional shape, and the refractive index of light is reduced. Can be constant.

The resin melted under pressure is injected from the center of the upper mold 10 and flows from the center of the lower mold 14 toward the outer periphery. A substrate with good appearance and birefringence characteristics can be made without hindrance.

In the above description, an example of a DVD in which an optical disk whose surface is protected is bonded to two substrates has been described. However, the present invention can be similarly applied to another single-plate optical disk, for example, a CD. (See FIG. 11).

The present invention can be similarly applied to a DVD-RAM in which a phase-change thin film or the like is provided on the information recording surface and writable.

Further, in the present embodiment, integral molding by resin molding is performed, but fine projections may be printed on the surface of the substrate.
A screen 16 having an opening 16a serving as a projection thereon is provided, and a projection material 18 provided on the screen 16 is filled in the opening 16a with a squeegee 17 to provide a projection on the transparent substrate 1, and a screen printing method shown in FIG. As shown in the figure, the projection material 21 is filled in the concave portion 19 of the mold 19a, and the transfer means 2
0 is pressed against the mold 19 and the projection material 21 is transferred to the transfer means 20.
Any method, such as tampo printing, in which the projections 21 are formed on the transparent substrate 1 by attaching the transfer means 20 to the transparent substrate 1 and the transfer means 20, or offset printing, ink jet, or the like, may be used.

[0035]

As described above, according to the present invention,
By providing a projection on the light incident slope of the optical disk, it is possible to prevent fingerprints and scratches from being formed, and to read or write information with high reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical disc according to an embodiment of the present invention.

FIG. 2 is a plan view of the optical disc viewed from the direction of arrow A in FIG. 1;

FIG. 3 is a diagram showing a relationship between a finger and a minute projection provided on an optical disc;

FIG. 4 is a plan view of an optical disc according to a second embodiment of the present invention.

FIG. 5 is a view showing a mold apparatus for manufacturing the optical disc of the second embodiment.

FIG. 6 is a sectional view of a conventional optical disk.

FIG. 7 is a diagram showing scratches on an optical disc;

FIG. 8 is a view showing a projection shape according to the embodiment of the present invention.

FIG. 9 is a diagram showing the relationship between a finger and a minute projection provided on an optical disc;

FIG. 10 is a diagram showing the relationship between protrusions of an optical disc and laser light.

FIG. 11 is a sectional view of a compact disc.

FIG. 12 is a diagram showing a method of manufacturing a projection of an optical disc according to an embodiment of the present invention.

FIG. 13 is a diagram showing a method for manufacturing protrusions of an optical disc according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Unevenness 3 Aluminum thin film 4 Adhesive 5 Transparent substrate 6 Light incident slope 7 Projection

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41J 3/407 B41J 3/00 F B29L 17:00 (72) Inventor Shigeru Kondo 1006 Kadoma, Kazuma, Kadoma, Osaka Address: Matsushita Electric Industrial Co., Ltd. (72) Inventor: Yuichi Nakajima 1006, Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Taro Tsujii 1006, Odakadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Terms (reference) 2C062 RA01 4F206 AA21 AA28 AH79 JA07 JQ81 5D029 KB11 LB02 PA10 5D121 AA02 DD02

Claims (9)

[Claims] 1. An optical disk having a projection for protecting an information recording area on an inclined surface of an optical disk on which light beams for reading and writing are incident. 2. The optical disk according to claim 2, wherein the projection prevents a fingerprint or a scratch from being attached to the bottom surface of the inclined surface. 3. The optical disk according to claim 1, wherein a large number of minute projections are provided on an inclined surface of the optical disk on which light beams for reading and writing are incident. 4. The optical disk according to claim 1, wherein a linear projection is provided on an inclined surface of the optical disk on which light beams for reading and writing are incident. 5. The optical disk according to claim 4, wherein the linear protrusion extends radially from the center of the optical disk. 6. The optical disk according to claim 4, wherein the linear projections are arranged in a staggered manner. 7. The optical disk according to claim 2, wherein the projection is provided at least for a range of information recording. 8. An optical disc having a surface on which information is recorded and having a surface for recording information provided on one surface of a transparent substrate, and a single plate or two substrates bonded together, a large number of minute light is incident on the surface on which light is incident. An optical disk provided with protrusions. 9. An optical disk in which the formation of projections and depressions serving as a recording surface and the projections for protecting an information recording area are simultaneously resin-molded on a transparent substrate, a recording thin film such as aluminum is formed on the projections and depressions, and a protective layer is provided on the thin film. Manufacturing method.