JP2009163858A - Optical information recording media and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording media capable of forming a BCA mark without damaging a protective layer and an optical transmission layer, and of highly reliably recording main information. <P>SOLUTION: The optical information recording media contains at least an optical reflective layer, an optical recording layer, the protective layer, and the optical transmission layer formed in this order on the main surface of a substrate, and has a main-information area for recording main information which can be optically read by irradiation with a laser beam and a sub-information area formed in the inner peripheral side from the main information area, on which an optically readable mark is recorded. The optical information recording media is produced by the steps of: forming at least one layer including the optical reflective layer; irradiating the sub-information area with a laser beam, thereby partly removing the at least one layer to record the mark on the area; and forming the layers above the removed layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical information recording medium and a method for manufacturing the same, and more specifically, in addition to a main information recording area for recording main information, an optical signal having a sub information recording area for recording sub information of barcode-shaped marks. The present invention relates to an information recording medium and a manufacturing method thereof.

In recent years, optical information recording media have been required to increase information recording density in order to record high-definition video data. In view of this, an optical information recording medium in which writing is performed with a laser beam having a shorter wavelength near 360 to 450 nm on the shorter wavelength side, for example, around 405 nm has been developed. As one of them, a light reflecting layer and a recording layer are formed on the light incident surface side of a resin substrate having a thickness of 1.1 mm as in a Blu-ray disc (BD-R). There has been proposed an optical information recording medium having a structure in which a light transmission layer having a thickness of 0.1 mm is provided on the formed surface or a structure in which the light transmission layer is provided through a protective layer.
In such an optical information recording medium, a light reflecting layer and a recording layer are sequentially formed on a resin substrate on which a guide groove (also referred to as a pregroove) is formed on a light incident side surface, and a light transmissive layer is formed thereon. A light-transmitting layer made of resin is provided, and is formed to have the same diameter and thickness as a recordable CD (referred to as CD-R) and a recordable DVD (referred to as DVD ± R). In some cases, a protective layer made of a light-transmitting inorganic material is provided between the recording layer and the light-transmitting layer in order to protect the recording layer. The recording layer of such an optical information recording medium is composed of an organic substance containing a dye such as an azo dye or a cyanine dye, or an inorganic substance such as Si, Cu, Sb, Te, or Ge, and laser irradiation for recording. Data is recorded by forming pits.

On the other hand, in an optical information recording medium (hereinafter sometimes referred to as “optical disk”), management information such as a serial number or lot number is converted into a bar code and a mark is recorded on the optical disk. A method for identifying whether or not the optical disc is a disc is used.
Conventionally, as a method for recording the identification information, in an optical disc such as a DVD-ROM, a mark (hereinafter, abbreviated as “BCA mark”) is recorded on a BCA (Burst Cutting Area) as a barcode. A method of reading a BCA mark with an optical head provided in a reproducing drive has been proposed and put into practical use (Patent Documents 1 to 4, etc.). This method is a method of recording information by melting a reflective layer of a disk by laser irradiation to form a non-reflective portion and arranging the non-reflective portion in a bar code shape.

The recording of identification information using the BCA mark has been studied in an optical disk using a short-wavelength laser beam such as an ultraviolet laser as in the above-described DVD-ROM. In the Blu-ray disc, it is described that a barcode recording unit that emits a BCA signal is formed by irradiating a laser beam from a transparent sheet side toward a reflection layer in a BCA equivalent region.
JP 2000-222743 A JP 2006-202487 A JP 2006-294195 A JP 2005-196940 A JP 2006-120188 A JP 2001-126325 A

However, the conventional BCA mark is currently formed by a method of performing recording by irradiating a laser beam to a manufactured optical disk, burst cutting, that is, melting a light reflection layer and making a hole in the reflection film. Therefore, the above-described Blu-ray disc has a problem that damage to the protective layer and the cover layer (light transmission layer) is large.
That is, since the light reflection layer in the Blu-ray disc or the like has a high reflectance with respect to blue-violet laser light, an Ag-based reflection film containing Ag as a main component is used, but has a high thermal conductivity. In addition, a laser with high output power is required for marking the BCA mark. As a result, the protective layer and the light transmission layer which are the upper layers of the light reflection layer are damaged.
Therefore, if the thermal conductivity of the light reflecting layer is lowered or the reflective film thickness is made thin so that burst cutting can be performed with low power, the problem that characteristics and reliability in the normal recording area deteriorate will become apparent. To do.
Further, when the reflective layer is burst-cut after completion of the optical disc, the reliability becomes low, such as durability under high temperature and high humidity, since it is the same as a state where pinholes are opened in the reflective film. In order to prevent this, a material having higher corrosion resistance than the reflective film material used so far in DVD-ROM or the like is required.

  Regarding the optical disc on which the BCA mark is formed, in Patent Document 2 and Patent Document 3, an Ag alloy for forming a reflective film that can easily perform laser marking, that is, low thermal conductivity, low melting temperature, high corrosion resistance, heat resistance, etc. An Ag-based alloy having the following has been proposed. However, these relate to a two-layer read-only optical disc. As described above, in the Blu-ray disc, if the thermal conductivity of the light reflecting layer is lowered, there is a problem that characteristics and reliability in a normal recording area deteriorate, so the Ag alloy described in these patent documents is applied as it is. I can't do it.

  Further, in Patent Document 4, in an information recording medium provided with an information recording layer additionally provided with a bar code mark and other information recording layers, the thermal conductivity of the material of the other information recording layer is indicated by the bar code mark. It has been proposed to set it to 1.5 times or more the thermal conductivity of the information recording layer material additionally recorded. This also has a first information recording layer and a second information recording layer via an intermediate layer, and a barcode-like BCA mark is recorded on the reflective film which is the first information recording layer. The present invention relates to a reproduction type information recording medium of a type that reproduces information from a light reflection layer that is a second information recording layer.

  Further, in Patent Document 6, it is proposed to form a bar code by using sputtering masking without using burst cutting. However, this relates to a conventional optical disc such as a DVD-ROM provided with only a reflective layer on a substrate. Moreover, since the masking has a width of about several tens of μm, it is buried immediately during continuous production, and mask replacement frequently occurs, which is not realistic.

In this way, in a Blu-ray disc having a sub-information area in which an optically readable mark is recorded, there is no occurrence of damage to the protective layer and the cover layer, and no occurrence of voids due to removal of the reflective layer. At present, a high optical disc has not yet been obtained.
An object of the present invention is to solve the above-mentioned problems in a Blu-ray disc having a sub-information area in which an optically readable mark is recorded, and to have good recording characteristics with almost no noise in an electric signal and to form an optical disc An object of the present invention is to provide a highly reliable optical disk having no voids in a layer.

  As a result of intensive studies to achieve the above object, the present inventors do not record the BCA mark after completion of the optical disk, but record the barcode-like BCA mark after forming the reflective film or after forming the optical recording layer. After forming the BCA mark in which the light reflecting layer or the optical recording layer is melted and removed in the form of a bar code, the optical recording layer or protective layer on the upper surface, and the light transmitting layer are sequentially formed. The knowledge that all the above-mentioned problems can be solved was obtained.

The present invention has been completed based on these findings, and is as follows.
(1) At least a light reflection layer, an optical recording layer, a protective layer, and a light transmission layer are formed in this order on one main surface of the substrate, and laser light is applied to these formation surfaces. Light having a main information area for recording main information that is irradiated and optically readable, and a sub information area in which a mark that can be optically read is recorded on the inner circumference side of the main information area In an information recording medium,
The mark in the sub information area is a portion where at least one layer including the light reflecting layer is removed, and a layer above the removed layer is formed in the removed portion. A characteristic optical information recording medium.
(2) The optical information recording medium according to (1), wherein the removed layer is only the light reflecting layer.
(3) The optical information recording medium according to (1), wherein the removed layers are the light reflecting layer and the optical recording layer.
(4) The optical information recording medium according to any one of (1) to (3), wherein the mark has a bar code shape.
(5) At least a light reflection layer, an optical recording layer, a protective layer, and a light transmission layer are formed in this order on one main surface of the substrate, and can be optically read by irradiating laser light. In a method for manufacturing an optical information recording medium, comprising: a main information area for recording main information; and a sub information area in which a mark optically readable on the inner circumference side of the main information area is recorded.
After at least one layer including the light reflecting layer is formed, and after recording the mark by irradiating the sub information area with laser light and removing the at least one layer including the light reflecting layer in the area A method for producing an optical information recording medium, comprising sequentially forming a layer above the removed layer.
(6) After the light reflecting layer is formed, the sub-information area is irradiated with laser light, and a mark is recorded by removing a part of the light reflecting layer in the sub information area. (5) The method for producing an optical information recording medium according to (5), wherein the layers are sequentially formed.
(7) After the light reflecting layer and the optical recording layer are formed, the sub-information area is irradiated with laser light, and a part of the optical recording layer and the light reflecting layer in the area are removed to record a mark. (5) The method for manufacturing an optical information recording medium according to (5), wherein layers above the optical recording layer are sequentially formed.
(8) The method for manufacturing an optical information recording medium according to any one of (5) to (7), wherein the mark is formed in a bar code shape.

  According to the present invention, since mark recording is performed under conditions that do not cause damage to the protective layer, the light transmission layer, and the like, good recording signal characteristics without electrical signal noise when recording in the main information area and can do. At the same time, an optical recording layer or a protective layer is formed in the portion where the light reflecting layer or the optical recording layer has been melted and removed, and the upper surface thereof is covered with the protective layer or the light transmitting layer. There are no holes or voids, and high reliability is obtained for durability under high temperature and high humidity.

The optical information recording medium of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view schematically showing one embodiment of an optical information recording medium 10 of the present invention. 2 is a partially enlarged sectional view showing a region surrounded by a broken line in FIG. 1 for explaining the outline of the internal structure, and FIG. 3 is a partially enlarged sectional view for explaining a conventional sub information region. 4 and 5 are partially enlarged cross-sectional views for explaining the sub information area of the present invention.

  As shown in FIG. 1, the optical disk 10 of the present embodiment has a center hole 5 and has a disk-like appearance with an outer diameter of about 120 mm, an inner diameter of about 15 mm, and a thickness of about 1.2 mm. On one main surface side of the optical disk 10, the sub information area 1 is provided in a range of 21.0 mm to 22.1 mm from the center of the center hole 5. In this region 1, a barcode-like BCA mark 4 provided with a portion having a light reflection layer on the circumference and a portion without the light reflection layer is formed. Also. On the outer peripheral side of the area 1, a main information area 3 is provided in a range of 23.0 mm to 58.5 mm from the center. 22.1 to 23.0 mm from the center is an intermediate area 2 between the sub information area 1 and the main information recording area 3, and its use is not limited and is an area that a user can freely use. Alternatively, it may be a reproduction-only area. Specifically, for example, it can be a mirror area having no groove or an HFM area having a groove.

  The outline of the internal structure of the area surrounded by the broken line in FIG. 1 of the optical disk 10 is as follows. As shown in FIG. 2, a disk-shaped substrate 11 having a thickness of about 1.1 mm and one main surface of the substrate 11 A spiral groove 12 is formed on the main surface of the substrate 11, and a light-absorbing substance composed of a light reflecting layer 13 that reflects laser light and an organic dye that absorbs laser light is mainly used as described later. An optical recording layer 14 included as a component, a protective layer 15, an adhesive layer 16 provided as necessary, and a light transmission layer 17 having a thickness of about 0.1 mm are provided in this order.

  The main information area 3 is recorded with optically readable main information on the optical recording layer 14 by irradiating laser light having a wavelength of 400 to 420 nm, for example, 405 nm, based on the recorded information. Further, on the inner periphery side of the main information area 3, there is provided a sub information area 1 for recording the sub information composed of the BCA mark 4 as described above, which is different from the main information.

The sub-information area 1 is an area for recording sub-information such as information specific to the medium. By irradiating laser light with a wavelength of 800 to 820 nm (for example, 810 nm), a part of the light reflecting layer is melted and removed. Thus, a portion having a reflective layer on the circumference and a portion 4 having no reflective layer are provided, and a barcode-like BCA mark 4 is formed.
FIG. 3 is an enlarged view of a part of the conventional sub information area 1.
As shown in FIGS. 3A and 3B, the conventional BCA mark formation is performed by irradiating a high-power laser beam onto the optical disk immediately before the final product on which each layer is formed, so that the BCA mark is formed. There may be a hole that extends to the protective layer 15 or the light transmission layer 17 on the upper surface of the portion 4 from which the reflective film 13 has been removed.

On the other hand, as shown in FIGS. 4A, 4B, and 4C, the optical disk 10 of the present invention records the optical recording on the portion where the BCA mark is written, that is, the portion 4 where the light reflecting layer 13 is not provided. The layer 14 is formed, and the protective layer 15 and the light transmission layer 17 are formed on the upper surface thereof.
In the optical disc 10 of the present invention, after forming the light reflecting layer 13 on the substrate 11, before forming another upper layer, a part of the sub information area is irradiated with laser light, and the light reflecting layer 13 is occasionally put. That is, the BCA mark 4 is formed. Thereafter, the optical recording layer 14, the protective layer 15, and the light transmission layer 17 are sequentially formed, so that the optical recording layer 14, the protection layer 15, and the light transmission layer 17 are sequentially formed in the portion 4 without the light reflection layer. The Therefore, the protective layer 15 and the light transmission layer 17 are not damaged when the BCA mark is formed. Moreover, since the BCA mark 4 is formed by removing the light reflecting layer cleanly, the BCA mark reading after completion becomes complete and affects writing and reading to the main information area. It can be said that there is almost nothing.

Further, as shown in FIG. 5, in the optical disc 10 of the present invention, a protective layer 15 is formed in a portion where a BCA mark is written in a portion 4 where there is no light reflecting layer 13 and no optical recording layer, and the optical layer 10 is formed on the upper surface thereof. Even if the transmission layer 17 is formed, the same effect as the example shown in FIG. 4 can be expected.
In this embodiment, the optical disc 10 of the present invention has a sub information area after forming the light reflecting layer 13 and the optical recording layer 14 on the substrate 11 as shown in FIG. 5A and before forming other upper layers. A part of the laser beam is irradiated with laser light, and a part where there is no light reflection layer 13 and no optical recording layer 14, that is, a BCA mark 4 is formed as shown in FIG. 5B. Thereafter, the protective layer 15 and the light transmission layer 17 are sequentially formed, so that the protection layer 15 and the light transmission layer 17 are formed in the portion 4 where the light reflection layer 13 and the optical recording layer 14 are absent. Therefore, the light transmission layer 17 is not damaged when the BCA mark is formed. When the light transmissive layer 17 is formed of a 0.1 mm light transmissive sheet, the adhesive layer 16 is applied to the side where the light transmissive layer 17 is to be bonded, and then bonded to the protective layer. By manufacturing in this way, the protective layer 15 or the light transmission layer 17 is not damaged when the BCA mark is formed. As in FIG. 4, reading of the BCA mark after completion is complete, and it can be said that writing to the main information area and reading are hardly affected.

In the present invention, as the substrate 11, various materials used as substrate materials for conventional optical information recording media can be arbitrarily selected and used. Specific examples include acrylic resins such as polycarbonate and polymethyl methacrylate, vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers, metals such as epoxy resins, amorphous polyolefins, polyester resins, and aluminum, and glass. These may be used together if necessary. Among the above materials, a thermoplastic resin is preferable from the viewpoint of moldability, moisture resistance, dimensional stability, and low price, and polycarbonate is particularly preferable.
When these resins are used, it is preferable to form the substrate 11 in a predetermined shape, for example, a disk shape in the case of an optical disk, by a method such as injection molding. The thickness of the substrate 11 is preferably in the range of 0.9 to 1.1 mm. Moreover, it is not restricted to this, For example, it can apply | coat on a base using an ultraviolet curable resin, and can also use it, hardening a coating film.

In the present invention, the spiral groove 12 is preferably formed in the sub information area 1 on the inner peripheral side and the main information area 3 on the outer peripheral side on one main surface of the substrate 11.
The groove 12 is formed in a mold used for injection molding of the substrate 11, and a mold plate called a stamper in which one main surface is subjected to fine processing of a spiral ridge having a pattern opposite to the groove 12 is formed. It is preferable that they are arranged and formed simultaneously with the injection molding of the substrate 11.

  The light reflecting layer 13 in the present invention reflects laser light for data recording and / or reproduction, and has a substrate for increasing the reflectivity of the laser light and imparting the function of improving the recording / reproducing characteristics. 11 and the optical recording layer 14. Examples of the forming method include vapor deposition, ion plating, and sputtering. By these methods, the light reflecting layer 13 is formed on the surface of the substrate 11 where the groove 12 is formed. Among these, the sputtering method is particularly preferable in terms of mass productivity and cost.

  The material constituting the light reflecting layer 13 may be any material that is preferably used in ordinary Blu-ray discs, such as a metal film such as Au, Al, Ag, Cu, or Pd, an alloy film of these metals, or a metal thereof. An alloy film in which a trace component is added to is preferably used.

  In the present invention, a BCA mark is formed in the sub information area 1 after the light reflecting layer 13 is formed. The BCA mark is formed by irradiating a part of the sub information area 1 with laser light to form a barcode-like mark in the sub information area 1 provided on the circumference of the center hole of the disc.

Next, the optical recording layer 14 is formed on the substrate after the BCA mark is formed in the sub information area 1 of the light reflecting layer 13.
The optical recording layer 14 preferably contains a light absorbing material composed of an organic dye that absorbs laser light. Among these, a dye-type optical recording layer in which pits are formed by laser beam irradiation and data is recorded is preferable. The organic dye is preferably a phthalocyanine dye, a cyanine dye, an azo dye, or the like. Dissolve to adjust the coating solution. Next, the coating solution is preferably applied by spin coating or screen printing through the light reflecting layer to form a coating film, and then dried by, for example, drying at a temperature of 80 ° C. for about 30 minutes.

(In the formula, A and A ′ represent one or more heteroatoms selected from a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom and a tellurium atom, and represent the same or different heterocycles. R _{21 to} R ₂₄ represent And each independently represents a hydrogen atom or a substituent, Y ₂₁ and Y ₂₂ represent the same or different heteroatoms selected from Group 16 elements in the periodic table.)

(In the formula, Φ ⁺ and φ represent an idrenine ring residue, a benzoindolenin ring residue or a dibenzoindolenine ring residue, respectively, L represents a linking group for forming a mono- or dicarbocyanine dye, X ^- represents an anion, m is an integer of 0 or 1).

In the present invention, the protective layer 15 is formed between the optical recording layer 14 and a light transmitting layer 17 to be described later for the purpose of adjusting recording characteristics, improving adhesiveness, protecting the optical recording layer 14, and the like. It is preferable.
As the protective layer _15, a transparent film made of _{SiO 2, ZnS-SiO 2,} Nb 2 O 5 -Al 2 O 3 , etc. are preferred. Examples of the forming method include vapor deposition, ion plating, and sputtering. The protective layer 15 is preferably formed on the surface on which the optical recording layer 14 is formed by these methods. Among these, the sputtering method is particularly preferable in terms of mass productivity and cost.

In the present invention, the adhesive layer 16 is an arbitrary layer formed in order to improve the adhesion between the protective layer 15 and the sheet-like transparent layer 17 described below.
Such an adhesive layer 16 is preferably composed mainly of an epoxy-based or other transparent reactive curable resin or an ultraviolet curable transparent resin. The adhesive layer 16 is applied to the protective layer 15 and / or the lower surface of a sheet-like light transmission layer 17 having a thickness of about 0.1 mm, which will be described later, by means such as spin coating or screen printing. After applying the adhesive layer 16, the protective layer 15 of the substrate 11 and the sheet-like light transmission layer 17 are joined together by the adhesive layer 16, and a disc-shaped optical information recording medium having a thickness of about 1.2 mm is obtained. can get.

In the present invention, the light transmission layer 17 is preferably made of a transparent resin. More specifically, for example, it is preferable to use a sheet made of a resin having good light transmission properties such as polycarbonate resin and acrylic resin, or to form a light transmission layer by applying these resins.
The thickness of the light transmission layer 17 is usually configured so that laser light having a wavelength in the vicinity of 400 nm to 420 nm is irradiated and data recording and / or reading from the optical recording layer 14 is performed on the optical recording layer 14. Usually, it is preferably 0.1 mm.
Although the specific example of the formation method of the light transmissive layer 17 is illustrated below, it is not restricted to these.
(A) On the substrate on which the protective layer has been formed, after applying an ultraviolet curable adhesive mainly composed of an acrylic resin, a disk-shaped sheet made of polycarbonate resin having a thickness of 0.1 mm is bonded, The adhesive is cured by irradiating with ultraviolet rays to obtain a disc-shaped optical information recording medium having a thickness of about 1.2 mm.
(A) A disc-shaped optical information having a thickness of about 1.2 mm by laminating a light-transmitting layer made of a 0.1 mm polycarbonate sheet on a substrate on which the protective layer has been formed via a transparent adhesive. A recording medium is obtained.
(C) On the substrate on which the protective layer is formed, a resin mainly composed of an acrylic resin is applied by a spin coating method, and then cured by ultraviolet rays to form a cover layer having a thickness of 0.1 mm. A 1.2 mm disc-shaped optical information recording medium is obtained.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited at all by these examples.
Example 1
<Manufacture of substrates>
A photoresist (photosensitive agent) is applied on a glass master by spin coating to a predetermined thickness to form a resist film, which is then exposed to a predetermined exposure width with a laser beam from a cutting device. A developer was dropped onto the resulting glass master and developed to form an uneven resist pattern corresponding to the groove of the substrate of the disk-shaped optical information recording medium.
Next, nickel was deposited on the glass master by plating, and this was peeled off, and the outer shape was trimmed into a disk shape to obtain a stamper.
Next, this stamper was set in a cavity of an injection molding apparatus, and polycarbonate resin was injected into the cavity to obtain a substrate 11 having a spiral groove on one main surface.

<Formation of light reflection layer>
Uniformly using an Ag alloy having a composition of Ag-0.5Bi-0.7Nd-6.0Sn (at%) as a target material by a sputtering apparatus on the main surface on which the spiral groove 12 is formed. Sputtering was performed to a thickness of 60 nm to form a light reflecting layer 13 having a thickness of 60 nm.

<Formation of BCA mark>
Next, in the sub information area 1 for forming the BCA mark of this optical information recording medium, a laser bias power of 200 mW is obtained with a BCA cutting device having a laser wavelength of 810 nm and an elliptical beam diameter of about 0.85 μm × about 35 μm. The BCA mark 4 having a circumferential width of 10 μm was formed under the conditions of a cutting speed of 1000 rpm, a radial beam feed amount of 6 μm, a recording start position of 21.0 mm, and a recording end position of 22.0 mm.

<Formation of recording layer, protective layer and light transmission layer>
A dye solution containing an azo organic dye represented by Chemical Formula 1 was applied on the substrate on which the BCA mark 4 was formed by spin coating so as to have a thickness of 60 nm.
Next, a protective film 15 having a thickness of 25 nm was formed on the substrate by sputtering ZnS—SiO ₂ using a sputtering apparatus.
Further, an ultraviolet curable adhesive mainly composed of an acrylic resin is applied on the substrate to form an adhesive layer 16, and then a disk-shaped sheet made of polycarbonate resin having a thickness of 0.1 mm is formed on the substrate. The light-transmitting layer 17 was formed by curing and bonding the adhesive by irradiating ultraviolet rays to obtain a disk-shaped optical disk having a thickness of about 1.2 mm.

FIG. 6 shows the result of observing the portion of the obtained optical disk where the BCA mark is formed with an optical microscope at a magnification of about 300 times.
FIG. 7 is a diagram showing a measurement image of an electronic signal of a portion where the BCA mark of the obtained optical disk is formed. This image is measured by moving the pickup to the BCA mark part at a linear velocity of 4.92 m / s with a recording and reproducing machine (model name ODU-1000) manufactured by Pulstec Corp. Was imaged and measured. The vertical axis in this image indicates the amplitude intensity of the electric signal, the horizontal axis indicates the scanning distance, and the state when scanning in the radial direction so as to cross the barcode is shown. The U-shaped signal portion corresponds to the portion where the BCA mark is formed.
As is clear from these figures, the obtained optical disc has a little noise on the edge part subjected to burst cutting, and the electric signal of the part corresponding to the bottom of the part where the BCA mark is formed is Ground level and almost no noise. It can be confirmed that a complete hole where the light reflecting film does not remain is opened.

(Example 2)
In the production of the optical disc shown in the first embodiment, the BCA mark 4 is formed in the same manner as in the first embodiment except that the light reflecting layer 13 and the optical recording layer 14 are formed. Created an optical disc.
FIG. 8 shows the result of observing a portion where the BCA mark is formed with an optical microscope at a magnification of about 300 times for such an optical disc.
FIG. 9 shows a measurement image of the electronic signal of the portion 4 where the BCA mark from which the light reflecting layer 13 and the optical recording layer 14 are removed is formed. Since this image measurement method is the same as that in the first embodiment, the description thereof is omitted.
As can be seen from these figures, the obtained optical disk 10 has a little noise at the edge part subjected to burst cutting, and the electric signal of the part corresponding to the bottom of the part where the BCA mark is formed is Ground level and almost no noise. It is almost the same as in the case of Example 1, and it can be confirmed that a complete hole in which the light reflecting film and the optical recording layer are not left is opened.

(Comparative example)
An optical disc was produced in the same manner as in Example 1 except that the BCA mark was formed in Example 1 after the disc was formed.
FIG. 10 shows the result of observing the portion of the obtained optical disk where the BCA mark was formed with the optical microscope in the same manner as described above.
FIG. 11 is a diagram showing the amplitude intensity measured under the same conditions as in FIG. 7, corresponding to the electronic signal of the portion where the BCA mark is formed on the optical disc in FIG.
As is clear from these figures, the edge of the burst-cut edge portion is not clear at the boundary of the hole portion in FIG. 10 and is also sharp when viewed from the measurement diagram of the amplitude strength of the electric signal in FIG. The presence of noise indicates that the groove is not completely formed. In particular, a considerable amount of noise is generated in the electrical signal measured at the bottom of the hole. From this, it can be confirmed that the light reflecting film is an incomplete hole.

  From these comparisons, the BCA mark can be completely written according to the configuration and the manufacturing method shown in the first and second embodiments of the present invention. At the same time, the optical recording layer 14 or the protective layer 15 is formed on the portion where the light reflecting layer of the BCA mark is removed, and the optical recording layer 14 or the protective layer 15 is continuously formed on the other surface to reflect the light. A protective layer, a light transmission layer, and the like are formed on the upper surface of the layer. Therefore, since no hole or void is formed around the upper surface of the portion where the light reflection layer 13 of the BCA mark is removed, the durability of the optical disk 10 of the above embodiment under high temperature and high humidity is as follows. It can be confirmed that the optical disk is superior to the optical disk of the comparative example without deterioration over time.

The top view which shows the whole structure of the optical information recording medium of this invention Partial enlarged sectional view showing the internal structure of the region surrounded by the broken line in FIG. 1 of the optical information recording medium of the present invention The schematic diagram which shows the part in which the BCA mark was formed of the conventional optical information recording medium The schematic diagram which shows the order of the part which forms the BCA mark of the optical information recording medium of this invention The schematic diagram which shows the other order of the part which forms the BCA mark of the optical information recording medium of this invention Photomicrograph of the portion of the optical information recording medium obtained in Example 1 where the BCA mark is formed Photograph of an oscilloscope showing the electrical signal of the portion where the BCA mark is formed on the optical information recording medium obtained in Example 1 Photomicrograph of the portion of the optical information recording medium obtained in Example 2 where the BCA mark was formed Photograph of an oscilloscope showing the electrical signal of the portion where the BCA mark is formed on the optical information recording medium obtained in Example 2 Micrograph of the portion where the BCA mark is formed on the optical information recording medium obtained by the comparative example Photograph of an oscilloscope showing the electrical signal of the portion where the BCA mark is formed on the optical information recording medium obtained by the comparative example

Explanation of symbols

1: sub information area 2: intermediate area 3: main information area 4: BCA mark 5: center hole 10: optical information recording medium 11: substrate 12: groove 13: light reflecting layer 14: optical recording layer 15: protective layer 16: Adhesive layer 17: light transmission layer

Claims (8)

On at least one main surface of the substrate, at least a light reflection layer, an optical recording layer, a protective layer, and a light transmission layer are formed in this order, and these formation surfaces are irradiated with laser light. An optical information recording medium comprising: a main information area for recording optically readable main information; and a sub information area in which an optically readable mark is recorded on the inner peripheral side of the main information area In
The mark in the sub information area is a portion where at least one layer including the light reflecting layer is removed, and a layer above the removed layer is formed in the removed portion. A characteristic optical information recording medium.   The optical information recording medium according to claim 1, wherein the removed layer is only the light reflecting layer.   The optical information recording medium according to claim 1, wherein the removed layers are the light reflection layer and the optical recording layer.   The optical information recording medium according to claim 1, wherein the mark has a bar code shape. At least a light reflecting layer, an optical recording layer, a protective layer, and a light transmitting layer are formed in this order on one main surface of the substrate, and main information that can be optically read by irradiating a laser beam In a method of manufacturing an optical information recording medium, comprising: a main information area for recording the optical information; and a sub-information area in which an optically readable mark is recorded on the inner circumference side of the main information area.
After at least one layer including the light reflecting layer is formed, and after recording the mark by irradiating the sub information area with laser light and removing the at least one layer including the light reflecting layer in the area A method for producing an optical information recording medium, comprising sequentially forming a layer above the removed layer.   After the light reflecting layer is formed, the sub-information area is irradiated with laser light, and a mark is recorded by removing a part of the light reflecting layer in the area, and then a layer above the light reflecting layer is formed. 6. The method of manufacturing an optical information recording medium according to claim 5, wherein the optical information recording medium is formed sequentially.   After the light reflecting layer and the optical recording layer are formed, the mark is recorded by irradiating the sub-information area with laser light and removing a part of the optical recording layer and the light reflecting layer in the area. 6. The method of manufacturing an optical information recording medium according to claim 5, wherein a layer above the optical recording layer is sequentially formed.   The method of manufacturing an optical information recording medium according to claim 5, wherein the mark is formed in a bar code shape.