JP2010009721A - Write once information recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a write once information recording medium which has good recording property. <P>SOLUTION: Concave parts and convex parts of the write once information recording medium are formed to include an organic dye layer on which recorded marks are formed by radiation of a short wavelength laser beam, and an optical density of the organic dye layer is equal to or less than 0.25. The pitch width of the concave parts ranges from 0.32 to 0.4 μm, and the width of the concave part is 50 to 80% to the pitch width of the concave part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a write-once information recording medium capable of recording and reproducing information with a short wavelength laser beam such as a blue laser beam.

  As a next-generation optical disk, an optical disk for recording / reproducing with a blue laser beam having a wavelength of about 405 nm is used.

  As a recording material for information recording using such a short wavelength laser beam, a recording medium using an organic dye material having an absorption maximum on the long and short wavelength side of the wavelength of the recording / reproducing laser beam (405 nm) has been developed. Has been. This is because when recording / reproduction is performed using blue laser light, it is necessary to reduce the molecular weight per molecule, so that the stability to ultraviolet rays and the storage durability deteriorate, and the stability to heat. This is because the recording mark has a problem of low contrast and resolution. In such an optical disk having absorption characteristics, the light reflectivity of the recording mark portion formed by irradiating laser light is lower than the light reflectivity before laser light irradiation, so-called H (High) to L ( Low) characteristics (see, for example, Patent Document 1).

  However, in recordable optical discs for short wavelengths using organic dyes, if the recording speed is increased by increasing the linear velocity during recording, the heat capacity of the dye itself is large and it is easy to store heat. As a result, the deterioration of the cross light characteristic is likely to occur. Further, the recording characteristics are deteriorated, and there is a disadvantage that a sufficient reproduction signal SN (Signal to Noise) ratio and bit error rate cannot be obtained.

In the condition where information is not recorded on the adjacent track, there may be a case where a temporary recording sensitivity can be obtained. However, if information is recorded on the adjacent track, the cross-write to the adjacent track is large, so that the reproduction signal SN ratio is large. And the bit error rate became high and did not reach a level suitable for practical use, and the recording characteristics were deteriorated.
2004-110385 gazette

  The present invention has been made in view of the above circumstances, and an object thereof is to obtain a write-once information recording medium having good recording characteristics.

  The present invention relates to a substrate on which concentric or spiral concave and convex portions are formed, and an organic dye layer formed on the concave and convex portions of the substrate, on which a recording mark is formed by irradiation with a short wavelength laser beam. And the organic dye layer has an optical density of 0.25 or less, a pitch width between the recesses of 0.32 to 0.4 μm, and a width of the recesses is a pitch between the recesses. Provided is a write-once information recording medium characterized by being 50 to 80% of the width.

  According to the present invention, a write-once information recording medium having good recording characteristics can be obtained.

  The write-once information recording medium of the present invention comprises a substrate on which concentric or spiral concave and convex portions are formed, and the recording mark is formed on the concave and convex portions of the substrate by irradiation with a short wavelength laser beam. A recording layer including an organic dye layer to be formed, the organic dye layer has an optical density of 0.25 or less, a pitch width between the recesses of 0.32 to 0.4 μm, and a width of the recesses The pitch width between the recesses is 50 to 80%.

  The write-once information recording medium is divided into the following two modes.

  According to the first aspect of the present invention, the substrate is a transparent resin substrate, the recording layer further includes a reflective film provided on the organic dye layer, and the recording and reproduction laser light is transmitted through the transparent resin substrate. It can be incident from the side.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a sectional view showing an example of a write-once information recording medium of the present invention.

  As shown in the figure, the write-once information recording medium according to the first aspect of the present invention includes a substrate 1 made of a resin such as polycarbonate having concentric or spiral recesses and projections, and a recess in the substrate 1. And a recording layer 4 formed on the convex portion. The recording layer 4 is provided on the concave and convex portions of the substrate 1 and includes an organic dye layer 2 on which a recording mark is formed by irradiation with a short wavelength laser beam and a reflective film 3 provided on the organic dye layer 2. The organic dye layer 2 has an optical density of 0.25 or less, for example, 0.1 or more and 0.2 or less, and a pitch width T1 between the recesses of 0.32 to 0.4 μm, for example, T1 = 0.4 μm. The width t is, for example, 50 to 80% of the pitch width T between the recesses, and for example, t = 0.26 μm. A dummy substrate 6 can be provided on the reflective layer 3 via an adhesive layer 5.

The recording laser light is incident from the transparent substrate 1 side.

  According to the second aspect of the present invention, the recording layer further includes a reflective layer between the substrate and the organic dye layer, an interface layer is formed on the organic dye layer, and a cover layer is further provided. It has been.

  FIG. 2 is a sectional view showing another example of the write-once information recording medium of the present invention.

  As shown in the figure, the write-once information recording medium 20 according to the second aspect of the present invention is formed on a substrate 9 on which concentric or spiral concave and convex portions are formed, and on the concave and convex portions of the substrate 9. A reflective layer 3 formed on the reflective layer 3 and a recording layer 4 including an organic dye layer 2 on which a recording mark is formed by irradiation with a short wavelength laser beam, and an interface layer 11 is formed on the recording layer 4 And a transparent cover layer 8 formed through the adhesive layer 7, the optical density of the organic dye layer 2 being 0.25 or less, for example 0.1 or more and 0.2 or less, and the pitch between the recesses The width T1 is 0.32 to 0.4 μm, for example 0.32 μm, and the width t of the recess is 50 to 80% with respect to the pitch width of the recess.

  In the present invention, recording characteristics can be sufficiently obtained by optimizing the optical density, thickness, and groove width of the organic dye layer laminated on the substrate.

  The thickness of the organic dye layer in the recess can be 50 nm or less, more preferably 20 to 45 nm, and the thickness of the organic dye layer on the protrusion can be 10 nm or less and 5 to 10 nm.

  A recording layer in which the light reflectance of the recording mark portion formed by irradiation with the short wavelength laser light is higher than the light reflectance before irradiation with the short wavelength laser light can be used.

  The recording film is composed of a dye part and an anion part made of an organometallic complex, part or all of which includes an organic dye whose maximum absorption wavelength region is on the longer wavelength side than the wavelength of the short wavelength laser beam. Can do.

  In the second aspect of the present invention, an interface layer for preventing mixing of the recording layer material and the cover layer material can be further provided between the recording layer and the cover layer. As the interface layer, oxides such as Si and GeZn, nitrides, sulfides, or a mixture thereof can be used.

  The organic dye layer used in the present invention may contain an organic dye containing a cation part made of monomethine cyanine and an anion part made of an azo metal complex, and a quencher made of a formazan metal complex, and has a maximum absorption wavelength region. It can exist in the long wavelength side rather than the wavelength of a short wavelength laser beam.

Further, the other organic dye layer used in the present invention may contain an organic dye containing a metal complex alone and a metal complex multimer, and the maximum absorption wavelength region exists on the longer wavelength side than the wavelength of the short wavelength laser beam. can do.

  Examples of the organic dye material used in the present invention include a cyanine cation-cobalt azo complex anion dye.

  The general formula of the cation moiety is shown in formulas (I), (VI), and (VIII).

  Formulas (II), (II ′), and (III) show the substituents of Formula (I), and Formula (VII) shows the substituents of Formula (VI).

  Specific structures of the cation moiety are shown in compounds C-1 to C-55.

  The general formulas of the azo complex anion of the anion part are shown in formulas A-1 to A-8.

Moreover, the general formula of the formazan complex used for this invention is shown to H-5, H-6, and a specific example is shown to H-1, H-2, H-3, and H-4.

(I)
In the formula, the ring A1 represents a benzene ring or a naphthalene ring, the ring A3 represents a 5-membered ring or a 6-membered ring, and the 5-membered ring and the 6-membered ring can be condensed with other rings and substituted. R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, the following general formula (II) ( II ′) or a substituent represented by (III). R7 represents an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, or a substituent represented by the following general formula (II) or (II ′) R12 represents a substituent represented by the following general formula (II) or (II ′), R20 represents a hydrogen atom, a hydroxyl group, a halogen atom, a nitro group, a cyano group, or a carbon atom number of 1 to 8 An alkyl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, a heterocyclic group having 2 to 20 carbon atoms, or an amino group. The methylene group in the alkyl group having 1 to 8 carbon atoms is -O-, -S-, -CO-, -COO-, -SO2-, -NH-, -CONH-, -N = CH,- C≡C— or —CH═CH— can be substituted. Anq- represents a q-valent anion, q represents 1 or 2, and p represents a coefficient for keeping the charge neutral.

In the general formula (II), the bond between L and T is a double bond, a conjugated double bond or a triple bond, L represents a carbon atom, and T represents a carbon atom, an oxygen atom, a sulfur atom or Represents a nitrogen atom, x, y, and z represent 0 or 1, s represents a number from 0 to 4, and R13 represents a hydrogen atom, a halogen atom, or a carbon atom that may be substituted with a halogen atom. Represents an alkoxy group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms which may be substituted with a halogen atom, and R14, R15 and R16 may each independently be substituted with a hydrogen atom, a halogen atom or a halogen atom. Represents a good aryl group having 6 to 12 carbon atoms, and R14 and R16 can be bonded to form a ring structure. In the general formula (II ′), the bond between L ′ and T ′ is double A bond or a conjugated double bond, L ′ Represents a carbon atom, T ′ represents a carbon atom, an oxygen atom, or a nitrogen atom, s ′ represents a number of 0 to 4, and the ring containing L ′ and T ′ may contain a hetero atom 6 Represents a member ring, naphthalene ring, quinoline ring, isoquinoline ring, anthracene ring or anthraquinone ring, and the ring containing L ′ and T ′ is substituted with a halogen atom, nitro group, cyano group, alkyl group or alkoxy group I can do it.

In the formula, Ra to Ri each independently represent a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms, and the methylene group in the alkyl group is substituted with —O— or —CO—. Z represents an alkylene group having 1 to 8 carbon atoms which may have a direct bond or a substituent, and the methylene group in the alkylene group is -O-, -S-, -CO-,- It may be substituted with COO-, -OCO-, -SO2-, -NH-, -CONH-, -NHCO-, -N = CH, or -CH = CH-, and M represents a metal atom.

In the formula, ring A1 represents a benzene ring or a naphthalene ring, x represents a carbon atom, an oxygen atom, a sulfur atom, a selenium atom, -R8R9-, -NH-, or -NR'-, and R, R21 and R22 Each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, or the following general formula (VII) Represents a substituent. R3, R4, R5 and R6 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 12 carbon atoms, and R3 and R4 are linked to each other. R25, which may form a ring, and R8 and R9 in X are each independently an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 20 carbon atoms, or the number of carbon atoms. It represents a 7 to 20 arylalkyl group or a substituent represented by the following general formula (VII), and R8 and R9 may be linked to form a ring. R25 and R34 each independently represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an aryl group having 6 to 30 carbon atoms, a halogen atom, a nitro group, It has a cyano group or a substituent represented by the above formula (III), and R23 and R24 can be linked to form a ring structure. The methylene group in the alkyl group having 1 to 8 carbon atoms can be replaced with —O— or —CH═CH—. Anq- represents a q-valent anion, q represents 1 or 2, and p represents a coefficient for keeping the charge neutral. D and J are the same as those in the following general formula (V).

In the formula, R3, R4, R5 and R6 are the same as in the general formula (V).

  In the formula, ring A1 represents a benzene ring or a naphthalene ring, and R19 represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkyl group having 6 to 30 carbon atoms. An aryl group, a heterocyclic group having 2 to 20 carbon atoms, a halogen atom, a nitro group, or a cyano group, n is a number of 1 to 5, and A1, R21, R22, R25, X, Anq- , P and q are the same as those in the general formula (VI).

  In the above general formula (VIII), examples of the heterocyclic group having 2 to 20 carbon atoms represented by R10 include pyridyl, pyrimidyl, pyridazyl, piperazyl, piperidyl, pyranyl, pyrazoyl, triazyl, pyrrolidyl, quinolyl, isoquinolyl, imidazolyl, Benzimidazolyl, triazolyl, furyl, furanyl, benzofuranyl, thienyl, thiophenyl, benzothiophenyl, thiadiazolyl, thiazolyl, benzothiazolyl, oxazolyl, benzoxazolyl, isothiazolyl, indolyl, eurolidyl, morpholinyl, thiomorpholinyl, 2-pyrrolidinone-1- Yl, 2-piperidone-1-yl, 2,4-dioxyimidazolose-3-yl, 2,4-dioxyoxazolidine-3-yl, and the like.

Examples of the alkyl group having 1 to 8 carbon atoms and the halogen atom represented by R19 include the groups exemplified in the description of the general formula (I), and includes 1 to 8 carbon atoms represented by R19. Examples of the alkoxy group and the aryl group having 6 to 30 carbon atoms include the groups exemplified in the description of the general formula (VI).

  Hereinafter, the present invention will be specifically described with reference to examples.

Example 1
A transparent polycarbonate substrate having a substrate thickness of 0.6 mm, a groove depth of 50 nm, and a pitch width between recesses of 0.4 μm and having the groove width sequentially changed from 10% to 90% was prepared.

An organic dye comprising a cation moiety on the substrate, for example, a monomethine cyanine dye represented by the formula C-1 and an anion moiety comprising, for example, an organometallic complex represented by the formula A-1 having cobalt as a central metal. A 1.2 wt% tetrafluoropropanol solution was applied by adjusting the number of revolutions of the spin coater to prepare a coated substrate adjusted to an optical density of 0.1-0.4 in increments of 0.1. Next, this coated substrate was dried at 80 degrees for 30 minutes. Next, an Ag alloy of Ag ₉₉ Bi ₁ was sputtered to 100 nm on this coated substrate by vacuum sputtering to form a reflective layer.

  Finally, as a dummy substrate, this disk was bonded to a transparent polycarbonate substrate having the same thickness using an ultraviolet curable resin as an adhesive, to prepare a sample disk.

Then, the disk wavelength 405 _nm, was set in an optical disc drive having an optical head comprised of N A 0.65, while rotating at a linear velocity of 6 m / s and 26m / s, 8/12 modulates (1,10RLL) Recorded the signal with.

Subsequently, the reproduction characteristic of this signal was evaluated by BER (Bit ERROR Rate).

  The limit of BER error correction of the optical disk drive is 3E-3, and if it is less than this, it is possible to read data normally without error. With the optical density and the recess width of the present invention, it was found that the above BER of 3E-3 or less was obtained, and it was confirmed that normal data reproduction was possible with error correction.

Example 2
A transparent polycarbonate substrate having a substrate thickness of 0.5 mm, a groove depth of 50 nm, a pitch width between recesses of 0.32 μm, and a groove width sequentially changed from 20% to 90% was prepared. On this substrate, an Ag alloy of Ag ₉₉ Bi ₁ was sputtered by 60 nm on the substrate by vacuum sputtering to form a reflective layer.

  Subsequently, an organic dye consisting of a monomethine cyanine dye represented by, for example, the above formula C-5 and an anion moiety comprising, for example, an organometallic complex represented by the above formula A-3 having cobalt as a central metal. A 2 wt% tetrafluoropropanol solution was applied by adjusting the rotation speed of the spin coater to prepare a coated substrate adjusted to an optical density of 0.1-0.4 in increments of 0.1.

  Next, this coated substrate was dried at 80 degrees for 30 minutes. Next, an interface layer of ZnS: SiO 2 was formed to a thickness of 20 nm by sputtering. On top of that, a cover layer made of a polycarbonate resin having a thickness of 95 μm was bonded using an ultraviolet curable resin to prepare a sample disk.

Disc recording / reproduction evaluation was performed using an ODU1000 tester manufactured by Pulstec Corp. having an optical system with a recording / reproducing light wavelength λ = 406 nm and N _A (numerical aperture) = 0.85. Recording / reproduction was performed on the recesses on the substrate. The disc used a (1, 7) RLL-NRZI-modulated mark length modulation signal for recording at a linear velocity of 5.3 m / s. The reference clock period T at 1 × speed is 15.15 nsec. (Channel clock frequency 66 MHz).

Jitter measurement is performed by equalizing the waveform of the recording signal using a limit equalizer and binarizing it. Distribution of time difference between the rising edge and falling edge of the binarized signal and the rising edge of the channel clock signal σ was measured with a time interval analyzer, and the channel clock period was set as T, and measured with σ / T. (Data to Clock Jitter Data to Clock Jitter).

  The limit as a practical characteristic of this disk is considered to be a jitter of 6.5% or less, and it can be seen that the above-mentioned jitter of 6.5% or less is obtained in the optical density and the recess width of the present invention. It was confirmed that the disks in this range have practical characteristics.

Sectional drawing showing an example of the write-once type information recording medium of this invention Sectional drawing showing another example of the write-once information recording medium of this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Organic pigment | dye layer, 3 ... Reflection layer, 4 ... Recording layer, 5, 7 ... Adhesive layer, 6 ... Dummy board | substrate, 8 ... Cover layer

Claims (10)

  A recording including a substrate having concentric or spiral concave and convex portions formed thereon, and an organic dye layer formed on the concave and convex portions of the substrate and having at least a recording mark formed by irradiation with a short wavelength laser beam. The organic dye layer has an optical density of 0.25 or less, a pitch width between the recesses of 0.32 to 0.4 μm, and a width of the recesses relative to a pitch width between the recesses The write-once information recording medium is characterized by being 50 to 80%.   The write-once information recording medium according to claim 1, wherein the thickness of the organic dye layer in the concave portion is 50 nm or less, and the thickness of the organic dye layer on the convex portion is 10 nm or less.   The light reflectance of the recording mark portion formed by the irradiation with the short wavelength laser light is higher in the recording layer than the light reflectance before the irradiation with the short wavelength laser light. The write-once information recording medium according to 1.   The organic dye layer is composed of a dye part and an anion part composed of an organometallic complex, and the organic dye having a maximum absorption wavelength region on the longer wavelength side than the wavelength of the short wavelength laser beam. The write-once information recording medium according to claim 1, further comprising:   A substrate having concentric or spiral concave and convex portions formed on the substrate, a reflective layer formed on the concave and convex portions of the substrate, and a reflective layer formed on the reflective layer. A recording layer including an organic dye layer on which a recording mark is formed by irradiation; and a cover layer formed on the recording layer, wherein the organic dye layer has an optical density of 0.2 or less, and between the recesses A write-once information recording medium having a pitch width of 0.32 to 0.4 μm and a width of the recesses of 50 to 80% with respect to a pitch width between the recesses.   6. The write-once information recording medium according to claim 5, wherein the thickness of the organic dye layer in the recess is 50 nm or less, and the thickness of the organic dye layer on the protrusion is 10 nm or less.   The light reflectance of the recording mark portion formed by the irradiation with the short wavelength laser light is higher in the recording layer than the light reflectance before the irradiation with the short wavelength laser light. 5. The write-once information recording medium according to 5.   6. The write-once information recording medium according to claim 5, further comprising an interface layer between the recording layer and the cover layer for preventing mixing of the recording layer material and the cover layer material. .   The organic dye layer contains an organic dye containing a cation part made of monomethine cyanine and an anion part made of an azo metal complex, and a quencher made of a formazan metal complex, and has a maximum absorption wavelength region of the short wavelength laser beam. The write-once information recording medium according to claim 5, wherein the write-once information recording medium is present on a longer wavelength side than the wavelength of the recording medium.   6. The organic dye layer contains an organic dye containing a metal complex alone and a metal complex multimer, and has a maximum absorption wavelength region on a longer wavelength side than the wavelength of the short wavelength laser beam. Write-once information recording medium described in 1.

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