JP2007109353A - Optical information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium which includes two light absorption layers containing recordable/reproducible light absorbing materials and a BCA having sufficient characteristics. <P>SOLUTION: In the optical information recording medium 10 which includes two light absorption layers containing recordable/reproducible light absorption materials by irradiation of a blue laser from one side, in order to facilitate formation of barcode information in the second layer in a depth side from a light incident side, the area of a first layer corresponding to the radial position forming the BCA of the second layer is used as a mirror part not including a groove or a pit, and the barcode information is recorded in a BCA forming area 17 having a groove or a pit in the second layer in the depth side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information recording medium, and more particularly to an optical information recording medium in which management information is recorded in bar code in addition to user information.

Conventionally, on the innermost circumference of an optical information recording medium such as a DVD-ROM, a burst cutting area (hereinafter referred to as BCA) for recording barcode information is used as an area for reading information without performing tracking servo control. May be provided). In the BCA, management information such as a serial number is recorded as identification information for each optical information recording medium and used for copyright protection (see Patent Documents 1 to 3).
Patent Document 4 discloses a system lead-in outside the user information area of the optical information recording medium for managing user information such as programs, data, and application information recorded in the user information area or protecting the copyright. In addition, the management information is recorded with the same modulation method as the user information area, while the management information is recorded with the BCA in a modulation method different from the user information area.
Such BCA is formed at the manufacturing stage of the optical information recording medium. Specifically, in the case of a DVD-ROM, for example, it is formed by removing the reflection film with a YAG laser (Patent Document 5). On the other hand, in the case of a write-once optical information recording medium DVD-R, the recording layer and the reflective film may be peeled off if the reflective film is removed with a YAG laser like a DVD-ROM. A BCA is formed by recording a barcode in a groove portion in the region.

JP 2000-149423 A JP 2000-222783 A JP 2001-043533 A JP-A-10-188361 Japanese Patent Laid-Open No. 06-203212

Incidentally, in recent years, a two-layer type optical information recording medium having two recording layers has been developed in response to an increase in information capacity. Among these, write-once optical information recording media using a dye material that absorbs laser light are used for many purposes because they cannot be rewritten.
In such an optical information recording medium having a light absorption layer containing a dye material that absorbs laser light, BCA is formed in a mirror area provided on the inner peripheral side of the user information area, and bar code information is recorded therein. Then, since the light absorption layer is thinner in the mirror area than in the user information area in which grooves or the like are formed, there is a problem that it is difficult to record barcode information with sufficient characteristics.

  Here, according to the study of the present inventor, when the BCA is formed in the same groove portion as the user information area instead of the mirror area as in the DVD-R, the barcode information recorded with the tracking removed is reproduced. In addition, it has been found that it is difficult to obtain bar code information with good characteristics because a cross track signal is generated due to eccentricity, the information signal of the bar code information fluctuates in amplitude.

  Furthermore, in an optical information recording medium having a two-layer recording layer containing a light-absorbing material that can be recorded / reproduced by irradiation with a blue laser from one side, the recording layer has a recording / reproduction layer as compared with an optical information recording medium having only one layer. Since the recording sensitivity is low, even when the recording power of the BCA recorder is set to the maximum level, barcode information that can obtain a sufficient signal intensity with a high degree of modulation is recorded on the second layer provided behind the light incident side. There is a problem that it is difficult.

The present invention has been made to solve the above-described problems.
That is, an object of the present invention is to provide an optical information recording medium having a BCA having sufficient characteristics in an optical information recording medium having two light absorbing layers containing a light absorbing material capable of recording and reproducing. .
Another object of the present invention is to provide a method for forming a BCA in a second layer provided on the back side as viewed from the light incident side in an optical information recording medium having two light absorption layers containing a light absorbing material. It is to provide.

Therefore, as a result of intensive studies to solve the problems of the preceding paragraph, the present inventors have developed a recordable / reproducible light-absorbing material in which user information is optically recorded along a concentric or spiral track by irradiation with a blue laser from one side. An optical information recording medium having a BCA having sufficient characteristics in an optical information recording medium having a BCA in which management information is recorded as bar code information inside concentric or spiral tracks. It came to be completed.
That is, firstly, in the optical information recording medium to which the present invention is applied, the BCA formation region of the second layer on the back side as viewed from the light incident side includes grooves or pits, and is almost the same as the BCA formation region of the second layer. A first layer of the same or greater radius region is composed of a mirror portion.
Second, the optical information recording medium to which the present invention is applied includes a track pitch (TP) of a groove or a pit in the BCA formation region of the second layer, a recording / reproducing laser wavelength (λ) of an optical disk drive, and a recording / reproducing. The numerical aperture (NA) of the objective lens of the pickup has a relationship of (TP × NA) /λ≦0.6.
Thirdly, in the optical information recording medium to which the present invention is applied, the first recording layer on the near side as viewed from the light incident side has a low to high recording in which the reflectance of the recorded mark is higher than the reflectance before recording. It is.
Fourth, the BCA forming method to which the present invention is applied is such that, in the optical information recording medium, a radial area substantially the same as or larger than the BCA forming area of the second layer is recorded on the front surface by a BCA recorder. The transmittance is increased, and then BCA is recorded in the BCA formation area of the second layer.

Thus, according to the present invention, the following (1) to (8) are provided.
(1) An optical information recording medium having two light-absorbing layers that can be recorded and reproduced by light irradiated from one side, provided on the second light-absorbing layer on the back side when viewed from the light incident side, A burst cutting area (BCA) formation area including grooves or pits for recording predetermined management information as barcode information, and a first light absorption layer on the near side as viewed from the light incident side, are provided in the second light absorption layer. And a mirror portion having no groove or pit formed in a region corresponding to a radial position of a burst cutting area (BCA) formation region of the light absorption layer.
(2) A first light absorption layer is formed on a mirror region where a groove or pit including a mirror portion is not formed, and on an outer peripheral side of the mirror region, and records user information along a concentric or spiral track. And a second light absorption layer is formed from the inner circumference side to the outer circumference side of the burst cutting area (BCA) formation area, and the user information is transmitted along a concentric or spiral track. The optical information recording medium according to (1), further comprising a second information area for recording.
(3) Groove or pit track pitch (TP) in a burst cutting area (BCA) formation region, recording / reproducing laser wavelength (λ) of a predetermined optical disk drive, and numerical aperture (NA) of an objective lens of a recording / reproducing pickup Satisfies the relationship expressed by the following formula (1). The optical information recording medium according to (1), wherein
(TP × NA) /λ≦0.6 Formula (1)
(4) The above (3), wherein the track pitch (TP), the recording / reproducing laser wavelength (λ), and the numerical aperture (NA) of the objective lens satisfy the relationship of the following expression (2): The optical information recording medium described.
0.45 ≦ (TP × NA) /λ≦0.6 Formula (2)
(5) The light absorption layer of the mirror portion is Low to High recording in which the reflectance after recording predetermined user information is higher than the reflectance before recording user information (1) The optical information recording medium described.
(6) The optical information recording according to (1), wherein the mirror portion is recorded on the entire surface with a predetermined recording power in a radius region substantially equal to or greater than a burst cutting area (BCA) formation region. Medium.
(7) The optical information recording medium as described in (1) above, wherein the light is a blue laser.
(8) A light absorption layer on the back side as viewed from the incident side of light incident from one side has a burst cutting area (BCA) formation region including grooves or pits, and light absorption on the near side as viewed from the light incident side In an optical information recording medium having a mirror portion not having grooves or pits formed in a region corresponding to the radial position of a burst cutting area (BCA) formation region on the layer, the mirror portion is recorded on the entire surface with a predetermined recording power, Thereafter, the barcode information is recorded in a burst cutting area (BCA) forming area, and a burst cutting area (BCA) forming method of an optical information recording medium.
(9) The above-mentioned (8), wherein the reflectance after recording predetermined user information in the light absorption layer of the mirror portion is Low to High recording in which the reflectance before recording user information is higher. A method for forming a burst cutting area (BCA) of the optical information recording medium described above.

  According to the present invention, barcode information recorded in a BCA formation area provided in an optical information recording medium having two light absorption layers can be reproduced with a high degree of signal modulation.

The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. The drawings used are for explaining the present embodiment and do not represent the actual size.
The optical information recording medium to which this embodiment is applied includes a first layer provided on the front side and a second layer provided on the back side when viewed from the incident side of light irradiated from one side.
FIG. 1 is a diagram for explaining an optical information recording medium 1 to which the present embodiment is applied. FIG. 1A is a diagram for explaining the first layer of the optical information recording medium 1, and FIG. 1B is a diagram for explaining the second layer of the optical information recording medium 1. As shown in FIG. 1A, the first layer of the disc-shaped optical information recording medium 1 having a central hole in the center is a flat mirror region provided around the central hole and in which no groove or pit is formed. 2, an information area 3 provided on the outer peripheral side of the mirror area 2 and for recording predetermined user information along a concentric or spiral track, and a mirror area 4 provided as necessary. A pit indicating management information or the like may be formed inside the information area 3.

  Further, as shown in FIG. 1B, the second layer of the optical information recording medium 1 includes a flat mirror region 5 provided around the center hole and in which no groove or pit is formed, and an outer peripheral side of the mirror region 5. A BCA formation area 6 that is formed and records management information with a bar code, a mirror area 7 provided on the outer peripheral side of the BCA formation area 6, and formed on the outer peripheral side of the mirror area 7, along a concentric or spiral track It comprises an information area 8 for recording predetermined user information and a mirror area 9 formed outside the information area 8. The mirror region 5, the mirror region 7, or the mirror region 9 may be provided as necessary. Further, a pit indicating management information or the like may be formed between the BCA formation area 6 and the information area 8.

  Next, FIG. 2 is a diagram illustrating a cross-sectional configuration of the optical information recording medium 10 to which the exemplary embodiment is applied. As shown in FIG. 2, in the optical information recording medium 10, the first layer on the near side when viewed from the light incident side is a light-transmissive first transparent substrate 13 and a predetermined transparent substrate 13 formed on the first transparent substrate 13. The information area 12 for recording the user information, the mirror area 11 provided on the inner circumference side of the information area 12, and the mirror area 14 provided on the outer circumference side of the information area 12. Further, the second layer on the back side when viewed from the light incident side includes a second transparent substrate 21, an information area 19 that is formed on the second transparent substrate 21 and records predetermined user information, and an inner circumference from the information area 19. BCA forming area 17 for recording management information and the like by a bar code, mirror area 16 further on the inner peripheral side than BCA forming area 17, and a mirror provided between BCA forming area 17 and information area 19 The region 18 is composed of a mirror region 20 provided on the outer peripheral side of the information region 19. The first layer and the second layer are bonded and integrated by the transparent adhesive layer 15.

  Here, in the mirror region 11 of the first layer, a region corresponding to the BCA formation region 17 provided in the second layer on the back side when viewed from the light incident side is a mirror portion having no groove or pit. The mirror portion is preferably formed in a portion corresponding to a radius region substantially equal to or larger than the radius region of the BCA formation region 17 of the second layer in the mirror region 11 of the first layer.

Next, in the BCA formation region 17 of the second layer, grooves or pits are formed at a predetermined track pitch (TP). The track pitch (TP) of the groove or pit in the BCA formation region 17 is preferably smaller than the track pitch in the information region 19.
Desirably, the track pitch (TP) of the groove or pit in the BCA formation region 17, the recording / reproducing laser wavelength λ of a predetermined optical disc driving device, and the numerical aperture NA of the objective lens of the recording / reproducing pickup are expressed by the following formulas ( It is preferable to satisfy the relationship 1).
(TP × NA) /λ≦0.6 Formula (1)

More preferably, the track pitch (TP) of the groove or pit in the BCA formation region 17, the recording / reproducing laser wavelength λ of a predetermined optical disk drive, and the numerical aperture NA of the objective lens of the recording / reproducing pickup are expressed by the following equations: It is preferable that the relationship (2) is satisfied.
0.45 ≦ (TP × NA) /λ≦0.6 Formula (2)
Here, for example, when the recording / reproducing laser wavelength λ is 405 nm and the numerical aperture NA of the objective lens is 0.65, the track pitch (TP) of the groove or embossed pit row in the BCA formation region 17 is adjusted to about 374 nm or less. Is desirable.

In the optical information recording medium 10 to which the present embodiment is applied, when the track pitch (TP) of the groove or pit in the BCA formation area 17 is made smaller than the track pitch in the information area 19, the optical disk drive optical used for recording and reproduction is used. It is important that the resolution is closer to λ / (2 · NA). Specifically, when the track pitch (TP) is reduced so that (TP × NA) / λ in the above-described formula (1) is 0.5 or less, the track pitch (TP) of the groove or pit in the BCA formation region 17 ) Is less than the optical resolution.
By making the track pitch (TP) of the groove or pit of the BCA formation area 17 close to the optical resolution or less than the optical resolution, the groove or pit of the BCA formation area 17 looks the same as the mirror portion from the optical disk drive. Therefore, the BCA reproduced by removing the tracking can reduce the amplitude fluctuation caused by the cross track signal of the groove or pit to a level that does not substantially affect the BCA.

Further, by setting (TP × NA) / λ in the formula (1) to 0.45 or more, the groove of the information area 19 and the like in the production of the master, which is one of the steps of producing the optical recording information medium 10, Using the same exposure apparatus (same laser) as that used for exposure to engrave pits in the management information area, grooves or pits in the BCA formation area 17 can be produced, and productivity is dramatically improved.
Here, when the recording / reproducing laser wavelength λ is 405 nm and the numerical aperture NA of the objective lens is 0.65, the track pitch (TP) of the groove or pit in the BCA formation region 17 is 280 nm or more.

  The depth of the groove or emboss pit in the BCA formation region 17 is not particularly limited, but a depth of 10 nm to 80 nm is usually preferable, and a depth of 20 nm to 50 nm is more preferable.

Next, a cross-sectional structure of the BCA formation region of the optical information recording medium to which this embodiment is applied will be described.
FIG. 3 is a diagram for explaining the cross-sectional structure of the BCA formation region of the optical information recording medium 22 to which the present embodiment is applied. As shown in FIG. 3, the BCA formation region of the optical information recording medium 22 includes a first transparent substrate 23 made of a light transmissive material and a first transparent substrate 23 as a first layer on the near side when viewed from the light incident side. It has the 1st light absorption layer 24 containing the light absorption material formed on the top, and the translucent reflective layer 25 formed on the 1st light absorption layer 24. Further, as the second layer on the back side when viewed from the light incident side, a second transparent substrate 30 in which grooves or pits having a predetermined track pitch (TP) are formed, and grooves or pits in the second transparent substrate 30 are formed. A reflective layer 29, a second light absorption layer 28 containing a light absorption material, and an interface layer 27, which are sequentially provided on the surface side. The first layer and the second layer are bonded and integrated by the transparent adhesive layer 26 so that the first translucent reflective layer 25 and the second interface layer 27 face each other.
As shown in FIG. 3, in the BCA formation region of the optical information recording medium 22, the first light absorption layer 24 on the near side as viewed from the light incident side includes the BCA formation region in the second light absorption layer 28 of the second layer. A flat mirror portion is formed in a portion corresponding to.

Next, each layer constituting the optical information recording medium 22 will be described.
(First transparent substrate, second transparent substrate)
The material of the first transparent substrate 23 and the second transparent substrate 30 is, for example, a highly transparent material having a refractive index with respect to laser light in the range of 1.4 to 1.6, and is preferably a resin excellent in impact resistance. Specific examples include polycarbonate, amorphous polyolefin, and acrylic, but are not limited thereto.
Incidentally, the first transparent substrate 23 between the first light-absorbing layer 24 of the mirror portion of the first _layer, may be provided enhancement layer and solvent layer of SiO 2, etc. ZnS-SiO _2.

  The first transparent substrate 23 and the second transparent substrate 30 are preferably produced by producing a master and a stamper and injection molding. The master is made as follows. That is, a glass master having a diameter of 200 mm and a thickness of 6 mm is prepared, and a photoresist is uniformly applied on one surface of the glass master using a spin coating method. The thickness of the photoresist is adjusted according to the depth of the pits or grooves. Next, the glass master disc coated with the photoresist is mounted on a cutting device.

  Note that the recording optical head of the cutting apparatus for producing the master is driven by a servo system that moves in the radial direction relative to the master. The recording radius position is monitored with a linear scale and controlled with a closed servo loop. Information data, management information, groove signals, etc. are generated from the formatter to drive the optical head. The entire system is managed by a controller, and servo control of the track pitch is also performed. In this servo control, the track pitch is controlled. The master is rotated by a spindle to form a unique servo loop. The spindle is driven by a spindle driver.

  According to the information sent from the formatter, the cutting apparatus irradiates the photoresist with laser light from the optical head and exposes it to form concentric or spiral pits or grooves. Adjust the laser light quantity to control the pit size and groove width. The glass master disc that has been cut is subjected to electroless plating as a pretreatment for plating on the pattern forming surface. Further, an Ni layer is formed by electroforming using the plated layer as a conductive film. Next, the stamper is obtained by polishing the surface of the Ni layer formed on the glass master and further peeling the Ni layer from the glass master. In addition, you may perform the electrically conductive film formation in the pre-processing of the said plating using a sputtering method or a vapor deposition method.

(First light absorption layer, second light absorption layer)
The material of the first light absorption layer 24 and the second light absorption layer 28 is preferably a light absorbing organic dye. Specific examples include cyanine dyes, polymethine dyes, triarylmethane dyes, pyrylium dyes, phenanthrene dyes, azo dyes, tetradehydrocholine dyes, triarylamine dyes, squarylium dyes, croconic methine dyes, and the like. It is not limited to these.
These organic dyes may be used singly or as a mixture of two or more organic dyes. Further, it may contain a quencher, other coloring matter, an additive, a polymer (for example, a thermoplastic resin such as nitrocellulose, a thermoplastic elastomer), metal fine particles, or the like.

  In the optical information recording medium 22 to which the present embodiment is applied, the first light absorption layer 24 of the mirror portion of the first layer has a low to high reflectance after recording information higher than the reflectance before recording. Polarity is preferred. In this case, among the organic dyes described above, an organic dye having a large absorption at the wavelength of the recording / reproducing light, that is, an organic dye having a large extinction coefficient k of the optical constant is desirable.

The first light absorption layer 24 and the second light absorption layer 28 are prepared by dissolving the above-described organic dye and any additive in a known organic solvent (for example, tetrafluoropropanol, ketone alcohol, acetylacetone, methylcellulose, toluene, etc.) In the case of the first light absorption layer 24, it is applied directly on the first transparent substrate 23, and in the case of the second light absorption layer 28, the reflection layer 29 formed on the second transparent substrate 30 is applied. Respectively.
As a coating method, a spin coating method is usually employed. The spin coating conditions may be performed by combining several rotation speeds from 300 rpm to 5000 rpm from the inner periphery to the outer periphery, and the spin coating conditions, the concentration of the organic dye solution, the viscosity, and the solvent drying speed are adjusted. Thereby, the film thickness of the 1st light absorption layer 24 and the 2nd light absorption layer 28 is controllable.

(Translucent reflective layer)
The translucent reflective layer 25 desirably has low light absorption, a light transmittance of 30% or more, and an appropriate light reflectance. For example, an appropriate transmittance and reflectance can be balanced by thinning a metal film having a high reflectance. Further, since the translucent reflective layer 25 is thin, a material having corrosion resistance is desirable. Furthermore, it is preferable to have a shielding property in order to prevent the organic dye from penetrating into the transparent adhesive layer 26. Examples of the metal of the translucent reflective layer 25 include gold, silver, aluminum, and alloys containing these, and can be formed by means such as sputtering using these metals. Those containing Ag as a main component are particularly preferred from the viewpoint of low cost and high reflectance.

The translucent reflective layer 25 is preferably made of a material having small crystal grains because large crystal grains of the metal film cause reproduction noise. Since pure silver tends to have large crystal grains, Ag is preferably used as an alloy. Among them, it is preferable to contain 0.1 atomic% to 5 atomic% of Ag as a main component and at least one element selected from the group consisting of Ti, Zn, Cu, Pd, Au, Ca, In and rare earth metals. When two or more of Ti, Zn, Cu, Pd, Au, Ca, In, and rare earth metal are included, each may be 0.1 atomic% to 5 atomic%, but the total of these may be 0.1 atomic% to 5 atomic% is preferable. Of the rare earth metals, neodymium is particularly preferred. Specific examples include AgPdCu, AgCuAu, AgCuAuNd, AgCuNd, AgCaCu, AgCaCu, and AgIn.
Moreover, Au has small crystal grains and is excellent in corrosion resistance and is preferable, but is more expensive than an Ag alloy. Further, as the semitransparent reflective layer 25, a multilayer film can be formed by alternately stacking low refractive index thin films and high refractive index thin films using a material other than metal such as SiO ₂ and can be used as a semitransparent reflective layer.

Examples of the method for forming the translucent reflective layer 25 include a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like, and the sputtering method is preferable in terms of productivity.
Incidentally, between the first light-absorbing layer 24 and the semi-transparent reflective layer 25 _may be provided other layers, such as SiO 2, _ZnS-SiO 2, enhancement layer, such as _Al 2 _{O 3} or the oxidation-resistant layer. Further, a protective layer may be formed on the translucent reflective layer 25, or a protective layer may not be formed. The protective layer may be any layer that can protect the light absorbing layer and the translucent reflective layer 25, and is formed of, for example, an ultraviolet curable resin or a silicone resin.

(Reflective layer)
The reflective layer 29 desirably has high reflectivity and excellent corrosion resistance. In order to increase the reflectance, the thickness of the reflective layer 29 is usually preferably 50 nm or more. More preferably, it is 80 nm or more. However, in order to increase the recording sensitivity, it is preferably thin to some extent, and when a thick reflective film is formed, the second transparent substrate 30 may be warped. Therefore, it is usually preferably 300 nm or less, and more preferably 200 nm or less. . Examples of the material of the reflective layer 29 include materials having a sufficiently high reflectance at the wavelength of the reproduction light. Specifically, for example, metals such as Au, Al, Ag, Cu, Ti, Cr, and Ni can be used alone or as an alloy. Among these, Au, Al, Ag, or an alloy thereof is preferable. The components forming the alloy include Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, In, Si, Ge, Te, Mention may be made of metals and metalloids such as Pb, Po, Sn, Bi and rare earth metals.

Among these, an Ag alloy is preferable because of its low cost, high reflectance, and excellent corrosion resistance. The Ag alloy contains Ag as a main component and contains at least one element selected from the group consisting of Ti, Zn, Cu, Pd, Au, Ca, In and rare earth metals in an amount of 0.1 atomic% to 5 atomic%. Is preferred. When two or more of Ti, Zn, Cu, Pd, Au, Ca, In, and rare earth metal are included, each may be 0.1 atomic% to 5 atomic%, but the total of these may be 0.1 atomic% to 5 atomic% is preferable. Of the rare earth metals, neodymium is particularly preferred. Specifically, AgPdCu, AgCuAu, AgCuAuNd, AgCuNd, AgCaCu, AgIn, and the like.
Examples of the method for forming the reflective layer 29 include a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like, and the sputtering method is preferable in terms of productivity.

(Interface layer)
The interface layer 27 is formed on the second light absorption layer 28 of the second layer, and is provided to shield the second light absorption layer 28 and the transparent adhesive layer 26 and prevent mixing of both layers. The transparent adhesive layer 26 is preferably made of a material that does not damage the second light absorption layer 28. However, when the transparent adhesive layer 26 is formed using a liquid ultraviolet curable resin, the ultraviolet curable resin is directly applied to the second light. In order to prevent the absorption layer 28 from being in contact with the absorption layer 28, it is desirable to provide an interface layer 27 between the transparent adhesive layer 26 and the second light absorption layer 28.

The material of the interface layer 27 is not particularly limited as long as it is not miscible with the second light absorption layer 28 and further miscible with the transparent adhesive layer 26. Moreover, it may serve other functions, and may further sandwich other layers as necessary. As such a material, an inorganic substance such as a metal or a semiconductor, an oxide, a nitride, or a sulfide of a metal or a semiconductor is preferable, and a transparent inorganic substance such as a dielectric is more preferable. Specifically, oxides such as silicon oxide (particularly silicon dioxide), zinc oxide, cerium oxide, yttrium oxide; sulfides such as zinc sulfide and yttrium sulfide; nitrides such as silicon nitride; silicon carbide; Mixtures with sulfur; and alloys described below are suitable. Further, a mixture of about 30:70 to 90:10 (weight ratio) of silicon oxide and zinc sulfide is also suitable. A mixture of sulfur and yttrium dioxide and zinc oxide (Y ₂ O ₂ S—ZnO) is also suitable.

  The thickness of the interface layer 27 is preferably 3 nm or more, more preferably 5 nm or more. When the thickness of the interface layer 27 is excessively thin, shielding is insufficient. Moreover, 100 nm or less is preferable, More preferably, it is 50 nm or less. If the interface layer 27 is too thick, the light transmittance may be reduced, and in the case of a layer made of an inorganic material, it takes time to form a film, resulting in a decrease in productivity and an increase in film stress. Examples of the method for forming the interface layer 27 include a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like. The sputtering method is preferable in terms of productivity.

(Transparent adhesive layer)
The transparent adhesive layer 26 is preferably made of a material that is transparent at the wavelength of the recording / reproducing light, has a high adhesive force, has a small shrinkage rate at the time of curing adhesion, and has high environmental preservation stability. In the present embodiment, since the focus servo is separately applied to the two light absorption layers (the first light absorption layer 24 and the second light absorption layer 28), the film thickness of the transparent adhesive layer 26 can be accurately controlled. preferable. The film thickness of the transparent adhesive layer 26 depends on the focus servo mechanism, and the distance tends to be smaller as the numerical aperture of the objective lens is higher. The film thickness of the transparent adhesive layer 26 is about 20 μm to 40 μm in the optical information recording medium 22 of blue laser on which two substrates (first transparent substrate 23 and second transparent substrate 30) having a thickness of 0.6 mm are bonded. Is preferred. The transparent adhesive layer 26 is preferably made of a material that does not damage the translucent reflective layer 25. Moreover, you may form a well-known inorganic type or organic type protective layer between both layers.
Examples of the material of the transparent adhesive layer 26 include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin (including a delayed curable type), and a pressure-sensitive double-sided tape. Among these, a solventless type ultraviolet curable resin is preferable because it is environmentally friendly and excellent in productivity. There are various types of ultraviolet curable resins, and any of them can be used as long as it is transparent.

  The transparent adhesive layer 26 can be formed by applying an ultraviolet curable resin and curing it by irradiating with ultraviolet light. As a coating method, a method such as a spin coating method, a screen printing method, a casting method, or the like is used as in the case of the first light absorption layer 24 or the like. Among these, a spin coating method is preferable. An ultraviolet curable resin having a viscosity of 20 to 1000 mPa · s at 10 ° C. to 40 ° C. is preferable because it can be applied without using a solvent.

Examples of the ultraviolet curable resin include a radical ultraviolet curable resin and a cationic ultraviolet curable resin, both of which can be used. As the radical ultraviolet curable resin, all known compositions can be used, and a composition containing an ultraviolet curable compound and a photopolymerization initiator as essential components is used. As the ultraviolet curable compound, monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, and polyfunctional methacrylates can be used alone or in combination of two or more as polymerizable monomer components.
The transparent adhesive layer 26 can also form grooves, pits, etc. using the 2P method.

(Other layers)
In addition, the optical information recording medium 22 to which this exemplary embodiment is applied may be provided with a printing layer or a printing receiving layer on the second transparent substrate 30 opposite to the light incident side, as necessary.
Recording on the optical information recording medium 22 is performed by irradiating the first light absorption layer 24 and the second light absorption layer 28 provided on the optical information recording medium 22 with laser light. In the portion irradiated with the laser beam, thermal changes of the substrate such as decomposition of the dye, heat generation, carbonization, melting of the substrate, deformation due to absorption of laser beam energy occur. The recorded information is reproduced by reading the difference in reflectance between the portion where the thermal change has occurred and the portion where the thermal change has not occurred with the laser beam.

  In the present embodiment, the wavelength of the blue laser of the apparatus used for recording and reproduction is preferably 390 nm to 430 nm, and more preferably 400 nm to 420 nm. The wavelength of the laser used for the writer for recording BCA (BCA recorder) may be any as long as it absorbs in the second light absorption layer 28 of the second BCA. For example, the wavelength is 390 nm to 430 nm, 620 nm. Examples of those having ˜720 nm and 780 nm to 830 nm can be mentioned. However, the wavelength of the BCA writer (BCA recorder) is not limited to this width.

  Here, in the optical information recording medium 22 to which the present embodiment is applied, the mirror portion of the first light absorption layer 24 having no groove or pit is substantially equal to or more than the BCA formation region of the second layer. It is preferable that the radius area is recorded on the entire surface with a predetermined recording power equivalent to the case where user information is recorded in the information area, for example, using a BCA recorder. By recording the entire mirror portion of the first light absorption layer 24, the transmittance of the mirror portion is increased. As a result, BCA can be easily recorded in the BCA formation region of the second layer.

Hereinafter, the present embodiment will be described more specifically based on examples. Note that this embodiment is not limited to the examples.
Example 1
A stamper A having a counterclockwise groove formed thereon was mounted on an injection molding machine, and an optical information recording medium grade polycarbonate resin was injection molded to obtain a first transparent substrate. The first transparent substrate is a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.59 mm. In the user information area, a modulated wobble groove having a track pitch of 400 nm, a half-value width of 0.23 μm, and a depth of 60 nm is formed. The inner periphery of the area is a mirror.
Next, a second transparent substrate was obtained by the same operation as described above, using the stamper B in which a clockwise groove was formed. The second transparent substrate is a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.59 mm, and a modulated wobble groove having a track pitch of 0.40 μm, a half-value width of 0.23 μm, and a depth of 35 nm is formed in the user information area. Yes. A straight groove having a track pitch of 350 nm, a half-value width of 0.23 μm, and a depth of 35 nm is formed in a BCA having a radius of 22.20 mm to 23.20 mm.

  Subsequently, a concentration of 0.7% by weight of a cyanine dye represented by the following chemical formula (1) and 0.3% by weight of an additive represented by the following chemical formula (2) is formed on the groove forming surface of the first transparent substrate. A tetrafluoropropanol solution (dye solution 1) was applied by spin coating. In addition, when apply | coating the said pigment | dye solution 1, the pigment | dye solution 1 was filtered with the filter and the impurity was removed. Next, the first transparent substrate coated with the dye solution 1 was dried at 90 ° C. for 1 hour, and further cooled at room temperature for 1 hour. Thus, the first light absorption layer was formed on the first transparent substrate. Further, a 12 nm thick translucent reflective layer made of an AgCuNd alloy was formed on the first light absorption layer by sputtering.

Next, an AgCuNd alloy was formed as a reflective layer on the groove forming surface of the second transparent substrate so as to have a thickness of 120 nm using a sputtering method. Next, a tetrafluoropropanol solution (dye solution 2) having a concentration of 0.7% by weight of the cyanine dye represented by the chemical formula (1) and 0.3% by weight of the additive represented by the chemical formula (2) is spin-coated. It was applied by the method. In addition, when apply | coating the said pigment | dye solution 2, the pigment | dye solution 2 was filtered with the filter and the impurity was removed. Next, the second transparent substrate coated with the dye solution 2 was dried at 90 ° C. for 1 hour, and further cooled at room temperature for 1 hour. Thus, the second light absorption layer was formed on the reflective layer of the second transparent substrate. Furthermore, an interface layer having a thickness of 15 nm made of ZnS—SiO ₂ was formed on the second light absorption layer by sputtering.

Subsequently, a radical polymerization type UV resin was applied on the semi-transparent intermediate layer of the first transparent substrate by a spin coating method, and placed in a bonding apparatus. Next, it installed in the bonding apparatus so that the interface layer of a 2nd transparent substrate might face the radical polymerization type UV resin application surface of a 1st transparent substrate. The inside of the apparatus was evacuated, and both disks were bonded so that bubbles were not generated in the transparent adhesive layer. The laminated disc was taken out from the laminating apparatus and cured by applying UV irradiation from the first transparent substrate side to obtain an optical information recording medium A on which a translucent adhesive layer having a thickness of 25 μm was formed. In the obtained optical information recording medium A, when information is recorded in the information areas of the first light absorption layer and the second light absorption layer with a laser beam having a wavelength of 405 nm, the reflectance of the recorded mark is higher than the reflectance before recording. It was a Low to High recording.
With respect to the optical information recording medium A thus obtained, a barcode signal was recorded in a BCA formation region having a radius of 22.20 mm to 23.20 mm of the second light absorption layer at a recording power of 190 mW with a BCA recording machine having a wavelength of 405 nm. . Table 1 shows the evaluation results of the BCA signal.

(Example 2)
In the optical information recording medium A used in Example 1, an optical information recording medium B was obtained by the same operation as in Example 1 except that the straight groove in the BCA formation region of the second transparent substrate was changed to a track pitch of 280 nm. . Next, a barcode signal was recorded on the optical information recording medium B in the BCA formation region having a radius of 22.20 mm to 23.20 mm of the second light absorption layer by the same operation as in Example 1. Table 1 shows the evaluation results of the BCA signal.

(Example 3)
In the optical information recording medium A used in Example 1, except that the straight groove in the BCA formation region of the second transparent substrate was changed to a pit having a track pitch of 320 nm, a width of 0.30 μm, and a length of 0.40 μm arranged in a staggered position. Obtained an optical information recording medium C by the same operation as in Example 1. Next, on the optical information recording medium C, a barcode signal was recorded in the BCA formation area of the second layer having a radius of 22.20 mm to 23.20 mm by the same operation as in Example 1. Table 1 shows the evaluation results of the BCA signal.

Example 4
In the optical information recording medium A used in Example 1, first, entire recording was performed with a recording power of 190 mW on a mirror area of the first light absorption layer having a radius radius of 22.10 mm to 23.30 mm by a BCA recorder. Subsequently, a barcode signal was recorded in the BCA formation area of the second layer having a radius of 22.20 mm to 23.20 mm by the same operation as in Example 1. Table 1 shows the evaluation results of the BCA signal.

(Comparative Example 1)
In the optical information recording medium A used in Example 1, the radius of the first transparent substrate is 22.20 mm to 23.20 mm (that is, the range corresponding to the BCA formation region of the second transparent substrate), the track pitch is 350 nm, and the half-value width is. An optical information recording medium D was obtained by the same operation as in Example 1 except that a straight groove having a depth of 0.23 μm and a depth of 60 nm was formed. Next, a barcode signal was recorded on the BCA formation area of the second layer having a radius of 22.20 mm to 23.20 mm on the optical information recording medium D in the same manner as in Example 1. Table 1 shows the evaluation results of the BCA signal.

(Comparative Example 2)
In the optical information recording medium A used in Example 1, an optical information recording medium E was obtained by the same operation as in Example 1 except that the straight groove in the BCA formation region of the second transparent substrate was changed to a track pitch of 400 nm. . Next, on the optical information recording medium E, a barcode signal was recorded in the BCA formation region having a radius of 22.20 mm to 23.20 mm of the second light absorption layer by the same operation as in Example 1. Table 1 shows the evaluation results of the BCA signal.

(BCA signal evaluation)
For each optical information recording medium prepared in each of Examples 1 to 4 and Comparative Examples 1 and 2, the focus was adjusted with a tester having an optical pickup having a laser beam having a wavelength of 405 nm and a lens having a numerical aperture of 0.65. Then, the BCA signal was reproduced with the tracking removed, and the minimum amplitude and the maximum amplitude of the reproduced signal were measured to obtain the modulation degree and fluctuation amount of the BCA signal.
FIG. 4 is a diagram for explaining an example of the BCA signal and the minimum amplitude and the maximum amplitude. As shown in FIG. 4, 31 is the minimum BCA amplitude, 32 is the maximum BCA amplitude, and 33 is the reflectance.
The minimum BCA amplitude (%) was obtained by the following equation using the minimum BCA amplitude 31 and the reflectance 33.
Minimum BCA amplitude (%) = (Minimum BCA amplitude 31 / Reflectance 33) × 100
The ratio between the maximum BCA amplitude 32 and the minimum BCA amplitude 31 was also obtained. The results are shown in Table 1.

From the results shown in Table 1, in the optical information recording medium provided with two light absorbing layers containing the organic dye (the first light absorbing layer and the second light absorbing layer), the back side when viewed from the incident side of the recording / reproducing light. A BCA for recording barcode information by grooves or pits is formed on the inner periphery of the user information area in the second light absorption layer, and the BCA of the second light absorption layer is formed in the first light absorption layer on the near side. It can be seen that the barcode information recorded in the BCA formation region of the second light absorption layer can be reproduced with a high signal modulation degree by forming a mirror portion at a position corresponding to (Example 1 to Example 4).
In this case, the fluctuation between the maximum BCA amplitude and the minimum BCA amplitude is reduced by setting the track pitch (TP) of the groove in the BCA of the second layer to be approximately equal to or less than the optical resolution of the optical disk drive (Examples 1 to 4). I understand that
Further, by recording the entire mirror portion of the first light absorption layer at a position corresponding to the BCA of the second light absorption layer with the BCA recorder (Example 4), the bar code information can be further increased. It can be seen that it can be reproduced with the modulation degree.

On the other hand, in an optical information recording medium provided with two light absorption layers containing an organic dye, the second light absorption layer on the back side as viewed from the incident side of the recording / reproducing light has grooves or grooves on the inner periphery from the user information area. A BCA for recording bar code information is formed by pits, and a groove or a pit portion is formed in the first light absorption layer on the near side at a position corresponding to the BCA of the second light absorption layer (Comparative Example 1, comparison). Example 2) It can be seen that the minimum BCA amplitude of the barcode information recorded in the BCA formation area of the second light absorption layer is reduced, and a sufficient signal modulation degree cannot be obtained.
It can also be seen that when the track pitch (TP) of the groove in the BCA of the second layer is increased (Comparative Example 2), the variation between the maximum BCA amplitude and the minimum BCA amplitude increases.

  As described above in detail, an optical information recording medium having two recording layers containing a light-absorbing material that can be recorded and reproduced by irradiating with a blue laser from one side is applied to a second layer on the back side as viewed from the light incident side. When forming a BCA for recording bar code information, a portion of the first layer corresponding to a radial position where the BCA of the second layer is formed is a mirror portion that does not include a groove or a pit. When the thickness of the light absorption layer of the first layer is reduced, the light transmittance of the mirror portion is increased and the amount of light reaching the BCA formation region of the second layer is increased. Further, by providing grooves or pits in the BCA formation region of the second layer and storing a light absorbing material in this portion, the recording sensitivity of the BCA formation region of the second layer is improved, and the bar code information has a high signal modulation degree. Can be reproduced.

  Also, by making the track pitch (TP) of the groove or pit in the BCA formation area of the second layer equal to or less than the optical resolution of the optical disk drive, the BCA signal reproduced without tracking can be crossed over the groove or pit. Amplitude fluctuation due to the track signal is reduced to such an extent that there is substantially no influence. As a result, it is possible to obtain a signal characteristic in which fluctuation of the maximum value and the minimum value of BCA is small.

  Further, when the light absorption layer of the first layer of the optical information recording medium is Low to High recording in which the reflectance of the recorded mark is higher than the reflectance before recording, the BCA of the first layer and the second layer are changed. A radial area corresponding to approximately the same position as or more than the radial position to be formed is entirely exposed by a BCA recording machine to increase the light transmittance of the exposed part, and then barcode information is displayed in the BCA formation area of the second layer. By recording, the recording sensitivity of the recorded barcode information can be improved.

It is a figure for demonstrating the optical information recording medium with which this Embodiment is applied. It is a figure explaining the cross-sectional structure of the optical information recording medium with which this Embodiment is applied. It is a figure explaining the cross-sectional structure of the BCA formation area | region of the optical information recording medium to which this Embodiment is applied. It is a figure explaining the example of a BCA signal, minimum amplitude, and maximum amplitude.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,10,22 ... Optical information recording medium, 2, 4, 5, 7, 9, 11, 14, 16, 18, 20 ... Mirror area | region, 3, 8, 12, 19 ... Information area | region, 6, 17 ... BCA Forming region, 13, 23 ... first transparent substrate, 15, 26 ... transparent adhesive layer, 21, 30 ... second transparent substrate, 24 ... first light absorbing layer, 25 ... translucent reflective layer, 27 ... interface layer, 28 ... second light absorption layer, 29 ... reflection layer

Claims (9)

An optical information recording medium having two light absorption layers that can be recorded and reproduced by light irradiated from one side,
A burst cutting area (BCA) forming region including a groove or a pit provided in the second light absorption layer on the back side as viewed from the light incident side and recording predetermined management information as barcode information;
Provided in the first light absorption layer on the near side as viewed from the light incident side, and formed in a region corresponding to the radial position of the burst cutting area (BCA) formation region of the second light absorption layer. Mirror part having no groove or pit,
An optical information recording medium comprising: The first light absorption layer is formed on a mirror region where a groove or pit including the mirror portion is not formed and on the outer peripheral side of the mirror region, and records user information along a concentric or spiral track. 1 information area,
A second information area in which the second light absorption layer is formed from an inner circumference side to an outer circumference side of the burst cutting area (BCA) formation area and records user information along a concentric or spiral track; The optical information recording medium according to claim 1, further comprising: The groove or pit track pitch (TP) in the burst cutting area (BCA) formation region, the recording / reproducing laser wavelength (λ) of a predetermined optical disk drive, and the numerical aperture (NA) of the objective lens of the recording / reproducing pickup The optical information recording medium according to claim 1, wherein the relationship of the following formula (1) is satisfied.
(TP × NA) /λ≦0.6 Formula (1) 4. The track pitch (TP), the recording / reproducing laser wavelength (λ), and the numerical aperture (NA) of the objective lens satisfy the relationship of the following expression (2). Optical information recording medium.
0.45 ≦ (TP × NA) /λ≦0.6 Formula (2)   The light absorption layer of the mirror portion is Low to High recording in which a reflectance after recording predetermined user information is higher than a reflectance before recording the user information. Optical information recording medium.   2. The optical information recording medium according to claim 1, wherein the mirror portion is recorded on the entire surface with a predetermined recording power in a radius region substantially equal to or greater than the burst cutting area (BCA) formation region.   The optical information recording medium according to claim 1, wherein the light is a blue laser. A light absorption layer on the back side as viewed from the incident side of light incident from one side has a burst cutting area (BCA) forming region including grooves or pits, and the light absorption layer on the near side as viewed from the light incident side. In the optical information recording medium having a mirror portion having no groove or pit formed in a region corresponding to the radial position of the burst cutting area (BCA) formation region,
A method of forming a burst cutting area (BCA) of an optical information recording medium, wherein the mirror portion is recorded on the entire surface with a predetermined recording power, and then barcode information is recorded in the burst cutting area (BCA) formation region.   9. The low-to-high recording in which the reflectance after recording predetermined user information in the light absorption layer of the mirror portion is higher than the reflectance before recording the user information. A method for forming a burst cutting area (BCA) of an optical information recording medium.

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