JP2008034027A - Recording and reproducing method and device for dye-based write-once dvd medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording and reproducing method and a device capable of obtaining a satisfactory recording waveform when performing recording on a dye-based write-once DVD medium at a high linear velocity. <P>SOLUTION: In the recording and reproducing method for the dye-based write-once DVD medium, in which, for a recording layer having an organic dye as a main component formed on a substrate having a guide groove, the shortest mark and a second shortest mark are recorded by a simple rectangular wave pulse, the third shortest or longer mark is recorded by a pulse in which a leading end part and a trailing end part are increased in power for specified periods of time, applied light quantity of a cooling pulse after the pulse trailing end in the mark recording is made at 0.1 mW or less for a specified period of time and in which the recording is reproduced by a reproduction light beam, when denoting the recording power in the pulse for the third shortest or longer mark as P<SB>2</SB>and the recording power at the leading and trailing parts where the power is increased for the specified periods of time as P<SB>1</SB>, the P<SB>1</SB>and P<SB>2</SB>satisfy expression (1) of P<SB>1</SB>=b×P<SB>2</SB>-a×P<SB>2</SB><SP>2</SP>/Pop (a≥0.2, b≥1.3), where, Pop represents a value of P<SB>2</SB>in the optimum recording of the medium. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a dye-based write-once DVD that can record and reproduce information by irradiating a light beam to cause optical changes such as transmittance and reflectivity in a recording layer, and can additionally write information. The present invention relates to a medium recording / reproducing method and apparatus.

Currently, high-speed development of DVD-R as a large-capacity optical disk is underway. As elemental technologies for improving the recording capacity, it is necessary to develop recording materials for minimizing recording pits, adopt image compression techniques such as MPEG2, and shorten the wavelength of semiconductor lasers for reading recording pits. .
Until now, only 670 nm AlGaInP laser diodes for bar code readers and measuring instruments have been commercialized as semiconductor lasers in the red wavelength range. It is being used in the optical storage market. In the case of a DVD drive, it is standardized by using a laser diode of two wavelength bands of 635 nm band and 650 nm band as a light source. On the other hand, a read-only DVD-ROM drive is commercialized at a wavelength of about 650 nm.

In general, a dye-based recordable DVD medium in which pits (marks) are formed by a heat mode is optimized for the pulse width and recording power of a recording pulse train generated by laser emission during recording at a specific recording speed. The state of marks and spaces formed changes with speed. That is, there is a shortage of heat capacity due to the leading heating pulse necessary for forming the mark, the heating temperature that reaches the optimum decomposition temperature differs, the average length of the mark varies, and the duty ratio of the optimum heating pulse differs As a result, a uniform mark width cannot be obtained, and thickening and thinning occur depending on the mark length, so that the jitter characteristics deteriorate.
The physical format of the DVD medium is standardized in a format in which a part of a land portion called a land prepit is cut in the case of a DVD-R medium format. When this method is adopted, if the land pre-pit signal (LPPb) is less than 0.16, pre-pit information such as a pre-pit address cannot be reproduced satisfactorily, and if it exceeds 0.32, the LPP signal itself behaves like a noise in the data area. Cause many data errors. Therefore, the LPP must finely adjust the cut width suitable for the recording material with a stamper to control the land cut width so that the LPPb is in the range of 0.16 to 0.32.

In order to solve the above-described problems of the prior art, as a technique focusing on a recording waveform when recording on a dye-based write-once DVD medium with one pulse and performing high linear velocity recording, Although there exist the patent documents 1-6 which concern, all have a solution means different from this invention.
Known examples of optical recording media using a dye in the recording layer include polymethine dyes or those using a polymethine dye and a light stabilizer as a recording material, tetraazaporphyrin (porphyrazine) dye or cyanine dye + azo metal chelate. A recording layer composed of a dye (salt-forming dye) and a reflective layer, a formazan (metal chelate) dye + other dye as a recording material, a dipyrromethene (metal chelate) dye + other dye as a recording material There are things to use and there is no time for enumeration. In addition, many recording materials are known that perform multi-pulse recording using a dye. To the best knowledge of the present inventors, recording is performed with one pulse on a dye-based recordable DVD medium as in the present invention. In addition, there is no literature that focuses on the recording waveform when performing high linear velocity recording.

JP 2004-303400 A JP 2004-303401 A Japanese Patent Application Laid-Open No. 2005-100579 JP-A-2005-243202 JP-A-2005-243208 JP-A-2005-293816

  An object of the present invention is to provide a recording / reproducing method and apparatus capable of obtaining a good recording waveform when performing high linear velocity recording on a dye-based recordable DVD medium.

The above problems are solved by the following inventions 1) to 16) (hereinafter referred to as the present inventions 1 to 16).
1) The shortest mark and the second mark from the shortest are recorded with a simple rectangular wave pulse on the recording layer mainly composed of an organic dye formed on the substrate having the guide groove, and the third from the shortest. The subsequent marks are recorded with a pulse whose output is increased for a certain period of time at the leading end and the trailing end of the pulse, and the irradiation light amount of the cooling pulse after the trailing end of the pulse at the time of the mark recording is set to 0. In a recording / reproducing method in which the recording is reproduced with reproducing light, the recording power in the pulse of the third and subsequent marks from the shortest is P ₂ , and the output is increased for a certain period of time at two positions, the front end and the rear end. A recording / reproducing method for a dye-based recordable DVD medium, wherein P ₁ and P ₂ satisfy the following formula (1) when the recording power is P ₁ .
P ₁ = b × P ₂ −a × P ₂ ^{2 /} Pop (a ≧ 0.2, b ≧ 1.3) (1)
(In the formula, Pop represents the P ₂ value at the time of optimum recording on the medium.)
2) The recording / reproducing method according to 1), wherein the cooling pulse irradiation time after the rear end of the pulse is 1/6 to 6/6 of the shortest long space.
3) The pulse width of the recording pulse that forms the mark with the shortest space length immediately before and the head heating pulse width are distinguished by whether or not the mark length is the shortest length. Is set to be longer than the head heating pulse width of the mark that is not the shortest length, and the pulse width of the recording pulse that forms the shortest length mark is distinguished by whether or not the space length immediately before the shortest mark is the shortest length. The recording / reproducing method according to 1) or 2), wherein the pulse width of the mark having the shortest immediately preceding space length is set shorter than the pulse width of the mark having the immediately preceding space length not having the shortest length.
4) The recording / reproducing method according to any one of 1) to 3), wherein the wobble frequency is a frequency corresponding to 4T to 96T, where T is a basic clock period.
5) The ratio “Wo / PP” between the wobble amplitude (Wo) and the push-pull amplitude (PP) of the track error detection signal for detecting and controlling the track error by the two-divided photodetector is 0.1 ≦ Wo / The recording / reproducing method according to any one of 1) to 4), wherein synchronization is performed within a range of PP ≦ 0.4.
6) The recording / reproducing method according to any one of 1) to 5), wherein the wavelength of the recording light is 600 to 720 nm.
7) The recording layer single layer has a refractive index n of 1.5 ≦ n ≦ 3.0 and an extinction coefficient k of 0.02 ≦ with respect to light in the wavelength range of the recording light and reproducing light wavelength ± 5 nm. The recording / reproducing method according to any one of 1) to 6), wherein k ≦ 0.2.
8) The recording / reproducing method according to any one of 1) to 7), wherein the decomposition start temperature of the recording layer is 100 to 360 ° C.
9) At least one optical recording medium selected from a reflective layer, a protective layer, an adhesive layer, a protective substrate, and a substrate surface hard coat layer as a constituent layer other than the recording layer on a substrate having a guide groove provided with wobbles The recording / reproducing method according to any one of 1) to 8), comprising a layer.
10) The recording / reproducing method according to 9), wherein the reflective layer is any one of gold, silver, and aluminum, or an alloy containing them as a main component.
11) The recording / reproducing method according to 9) or 10), wherein the protective layer comprises an ultraviolet curable resin.
12) An adhesive layer for bonding two substrates to form a recording medium having a double-sided structure is provided between the substrates, and the adhesive used for the adhesive layer is an ultraviolet curable resin. The recording / reproducing method according to any one of 9) to 11).
13) The shortest long mark and the second shortest mark are recorded with a simple rectangular wave pulse on the recording layer mainly composed of an organic dye formed on the substrate having guide grooves, and the third shortest is recorded. The subsequent marks are recorded with a pulse whose output is increased for a certain period of time at the leading end and the trailing end of the pulse, and the irradiation light amount of the cooling pulse after the trailing end of the pulse at the time of the mark recording is set to 0. The recording / reproducing method for reproducing the recording with a reproducing light can be carried out at 1 mW or less, and the recording power in the pulse of the third and subsequent marks from the shortest is P ₂ , and the recording power is constant at _{two positions of} the leading end and the trailing end. when high output recording power and P _1, the recording and reproducing apparatus of the dye-based recordable DVD medium which P ₁ and P ₂ are characterized by having a function to satisfy the following equation (1).
P ₁ = b × P ₂ −a × P ₂ ^{2 /} Pop (a ≧ 0.2, b ≧ 1.3) (1)
(In the formula, Pop represents the P ₂ value at the time of optimum recording on the medium.)
14) The recording / reproducing apparatus according to 13), which has a function of setting a time for irradiating the cooling pulse after the rear end of the pulse to a length of 1/6 to 6/6 of the shortest long space.
15) The pulse width of the recording pulse forming the mark having the shortest space length immediately before and the head heating pulse width are distinguished by whether or not the length of the mark is the shortest length, and the pulse width of the shortest length mark is determined. Is set to be longer than the head heating pulse width of the mark that is not the shortest length, and the pulse width of the recording pulse that forms the shortest length mark is distinguished by whether or not the space length immediately before the shortest mark is the shortest length. The recording according to 13) or 14), which has a function of setting a pulse width of a mark having the shortest immediately preceding space length to be shorter than a pulse width of a mark having the immediately preceding space length not having the shortest length. Playback device.
16) A dye-based write-once DVD medium, wherein information for performing the recording / reproducing method of any one of 1) to 3) is preformatted in advance.

Hereinafter, the present invention will be described in detail.
The present invention is characterized in that the optimum recording power of a basic recording pulse is defined.
Recording power control corresponding to the first aspect of the present invention, in which the shortest mark and the second mark from the shortest are rectangular wave pulses, and the pulse leading and trailing ends of the third and subsequent length marks are increased in output. An example of the waveform is shown in FIG.
In order to reduce the number of recording parameters, the recording power P ₀ of the shortest mark and the second mark from the shortest is usually high for a certain time at the leading and trailing edges of the pulses of the third and subsequent marks from the shortest. configured the same as the recording power P ₁ output reduction. The third and subsequent recording power in pulses of a mark length When _{P 2, P} 1 / _{P 2} is susceptible employed in a range of 1.10 to 2.00, preferably 1.20 to 1. The range is 70. With respect to the third and subsequent length marks, the length to increase the output by adding power to the leading and trailing ends of the pulse is 0.5 to 2 times the basic clock period T, that is, 0.5T. The range of ˜2T is particularly preferable, and the range of 0.2T to 3.0T can also be implemented.

In the prior art, when the recording strategy as shown in FIG. 4 is adopted, the ratio of P ₁ / P ₂ is set to be constant regardless of P ₁ (corresponding to a = 0 in the formula of the present invention 1). However, as a result of examination, it has been found that sufficient characteristics cannot be obtained in high-speed recording with such a recording power setting. Further, the optimum value of _P 1 / _{P 2} is found to be different depending on the value of _{P 1.} Specifically, when P ₁ is low power, P ₁ / P ₂ is set large, and when P ₁ is high power, P ₁ / P ₂ is set small so that the recording characteristics (jitter value) are reduced. I found it better. On the other hand, if there are many parameters for setting P ₁ and P ₂ , a burden is imposed on the recording drive to be controlled.
As a result of further investigation based on these findings, it has been found that if the recording power is controlled so as to satisfy the formula (1) defined in the present invention 1, the jitter characteristic margin with respect to the recording power can be improved. In the formula (1), at a ≧ 0.2, b ≧ 1.3, a constant that does not depend on the P _2, when to set a, the optimum value of b according to the medium, in the prior art Compared to this, the recording margin can be improved. The value of P ₁ is different by the recording medium and a recording apparatus, in general recording apparatus is largely influences the setting of the optimum recording power.
Normally, a is set to 1.5 or less, preferably 0.1 to 0.8, b is set to 1.3 to 3.0, preferably about 1.3 to 2.2, but varies depending on the medium. Therefore, it is difficult to limit the numerical value due to its nature. The Pop value is the P ₂ value when the jitter value is the lowest, and this value varies depending on the medium, the recording speed, and the recording pattern. Usually, the Pop when recording a DVD-R medium at 12x is 15 It will be about ~ 30mW.
In implementing the first aspect of the present invention, it is only necessary to change the setting value of the recording power, so that the application to the recording apparatus is easy.

In the first aspect of the present invention, at the time of mark recording, a cooling pulse is irradiated after the trailing end of the pulse of all the marks, and the irradiation light quantity is set to 0.1 mW or less for a certain period of time, thereby achieving high quality at a high linear velocity. Recording can be realized.
The present invention 2 prescribes a preferable irradiation condition of the cooling pulse provided after the rear end of each pulse, and the irradiation time of the cooling pulse is 1/6 to 6/6 of the shortest space length. In this range, the recording quality can be further improved.
By selecting the pulse waveform as described above, good recording can be performed with low jitter, particularly in high linear velocity recording.

In consideration of the influence of thermal interference, the pulse width of the recording pulse and the leading heating pulse width for forming the mark having the shortest space length immediately before are determined by whether the mark length is the shortest length or not. In order to distinguish, the pulse width of the shortest length mark is set longer than the head heating pulse width of the mark that is not the shortest length (as an example, in Table 1 described later, the immediately preceding space length is 3T, the recording mark length is 3T, and 4T to 14T) By referring to the case, recording with lower jitter can be realized.
Further, the pulse width of the recording pulse forming the shortest length mark is distinguished by whether or not the space length immediately before the shortest length mark is the shortest length, and the pulse width of the mark having the shortest space length is the shortest length. By setting the immediately preceding space length to be shorter than the pulse width of the mark that is not the shortest length (see, for example, the case where the recording mark length is 3T and the space length is 3T, 4T to 14T in Table 1 described later). Jitter recording can be realized.

The correction amount (length) for setting the head heating pulse width short is particularly preferably in the range of 0.02T to 0.10T. When the space length immediately before the mark to be formed is the shortest length, and the pulse width or head pulse width of the pulse forming the mark is substantially equal to that of the other marks, the space length immediately before the mark is caused by thermal interference. Shorter and jitter is slightly worse. Therefore, only in such a case, it is effective to shorten the pulse width for recording the mark or the head heating pulse width. Needless to say, if it is desired to further shorten the pulse width, it is effective to shorten the correction amount (front edge) of the pulse for recording the mark or the head heating pulse.
In addition, when the space length immediately before the mark to be formed is the shortest length, it is not preferable that the pulse width of the pulse forming the mark is shorter than 0.10 T because the mark length itself becomes too short.
The correction amount (length) when the pulse width of the shortest mark is set longer than that of other marks is preferably 0.05T to 0.25T. In particular, when the recording linear velocity increases, it becomes difficult to form the shortest length mark. Therefore, the pulse width of the shortest length mark is increased by correcting within the above range.

Specific examples of the correction amount of the pulse width or the leading heating pulse width are shown in Table 1 below.

Next, optical characteristics are listed as items necessary for the recording layer.
As an optical characteristic, the refractive index n of the recording layer single layer with respect to light in the wavelength range near the long wavelength near the recording / reproducing wavelength, that is, light in the wavelength range of recording light and reproducing light wavelength ± 5 nm is 1.5 ≦ n ≦. 3.0 and the extinction coefficient k is preferably in the range of 0.02 ≦ k ≦ 0.2. When n is less than 1.5, it is not preferable because it is difficult to obtain a sufficient optical change and the recording modulation degree becomes low. When n exceeds 3.0, the wavelength dependence becomes too high, and the recording / reproducing wavelength region However, it is not preferable because an error occurs. Further, when k is less than 0.02, it is not preferable because the recording sensitivity is deteriorated. When k exceeds 0.2, it is difficult to obtain a reflectance of 50% or more.
Note that the DVD is standardized at around 650 nm in a reproduction-only machine, but the wavelength of the recording light of the recording medium is standardized at 650 to 660 nm for general use in addition to 635 nm of the authoring-only medium. However, these wavelengths are only central wavelengths, and can be shifted to the short wavelength side and the long wavelength side due to variations in the manufacturing of the LD. In addition, due to the characteristics of the LD, the wavelength generally shifts to the longer wavelength side when the temperature rises. The present invention is a method that can be carried out at a recording wavelength of 600 to 720 nm including the above wavelength range.

Next, the wobble characteristics of the meandering guide groove provided on the substrate will be described. T for specifying the wobble frequency is a basic clock period. In the case of a DVD (4.7 GB) medium, the time is about 0.133 μm. About 38 nsec. It is.
Usually, the wobble frequency band corresponding to 150T to 400T is used. However, in this frequency band, when data is added regardless of frequency modulation or phase modulation, the wobble frequency is too low and the previous data is written. It is not suitable for high-density recording because there is a considerable gap between the added data. On the other hand, the DVD-R is provided with an LPP, and the data writing position is controlled by the LPP signal.
However, in the LPP method, if the signal amplitude of the LPP is too small, the LPP cannot be read satisfactorily. On the contrary, if the LPP is too large, the LPP signal itself leaks into the write data, resulting in frequent data errors. , LPP has a constraint of 0.16 ≦ LPPb ≦ 0.32, preferably 0.18 ≦ LPPb ≦ 0.26, and the cut width of the land must be finely controlled when forming the stamper.
On the other hand, if the high-frequency wobble is used, the LPP is not necessary, and the wobble is modulated and synchronized, so that a situation in which data errors occur frequently as in the LPP method does not occur. As defined in the fifth aspect of the present invention, the preferred frequency of the high frequency wobble is 4T to 96T. If the frequency is smaller than 4T, the frequency becomes too high to be detected, and there is a problem in terms of rotation control and address detection reliability. On the other hand, when the frequency is larger than 96T, the frequency is too low, and the gap is too wide at the seam when data is additionally written, causing problems such as a decrease in capacity and a decrease in data processing speed.

The wobble amplitude of the DVD medium to which the present invention is applied is a wobble amplitude (Wo) of a signal passing through an appropriate filter, for example, 4 MHz, 30 kHz high and low pass filter, and an appropriate filter, for example, a 30 kHz filter. If the ratio Wo / PP of the push-pull signal (PP) satisfies 0.1 ≦ Wo / PP ≦ 0.4, synchronization with wobble, which is the object of the present invention, is easy. Preferably, the range is 0.15 ≦ Wo / PP ≦ 0.30. If the value of Wo / PP is less than 0.1, the signal strength is insufficient to achieve synchronization, and if it exceeds 0.4, data portion errors tend to increase. However, as compared with the LPP method, the degree of influence on the data error occurrence of a medium having a large LPP is small, and the data error accompanying the increase in wobble amplitude is moderate.
Furthermore, when creating a stamper, an advanced cut width control technique is required to bring the LPP cut width of the LPP method within the range of 0.16 to 0.32 described above. In the high frequency wobble method of the present invention, however, The purpose can be achieved only by managing the high-frequency generation source and the wobble swing amount (the swing control amount can be created arbitrarily with a circuit that controls the wobble swing amount), so that the stamper yield and medium Yield can be dramatically improved.

Further, as the groove shape of the substrate having the above format, when a recording layer is formed by a solvent coating method using an organic dye, a preferable groove depth is 1000 to 2500 mm, and more preferably 1500. ~ 2000cm. If the groove depth is less than 1000 mm, the push-pull signal cannot be obtained sufficiently and tracking control cannot be performed. On the other hand, if the thickness exceeds 2500 mm, the transferability becomes undesirably reduced when the substrate is formed.
Further, when the dye recording layer is provided, the dye groove depth is preferably in the range of 1200 ≦ d1 × m ≦ 160000 when the wobble frequency is mT (m is a natural number) and the dye groove depth is d1. If d1 × m is less than 1200, a sufficient difference signal cannot be obtained, and sufficient tracking cannot be performed at the time of recording / reproduction. If d1 × m exceeds 160000, oscillation is reversed. Due to the limitation of the depth of the substrate groove due to the transfer limit of the substrate molding described above, it cannot substantially exceed 160000.
In addition, in order to ensure a recording density of 4 to 5 GB, the track pitch needs to be about 0.64 to 0.8 μm. Although the groove width varies depending on the recording material, it can be applied to a width of 0.18 to 0.40 μm in almost all organic materials.

Next, the layer structure of the dye-based write-once DVD medium that is the subject of the present invention, the necessary characteristics of each layer, and the constituent materials will be described.
FIGS. 1A to 1D are layer configuration examples of a normal write-once optical disc, and FIGS. 2A to 2C are layer configuration examples of a normal CD-R medium. ) To (c) are examples of the layer structure of the write-once DVD medium, but the preferred basic structure of the dye-based write-once DVD medium that is the subject of the present invention is as shown in FIGS. A first substrate and a second substrate (protective substrate) are bonded together with an adhesive with a recording layer in between.
The recording layer may be a single organic dye layer or a laminate of an organic dye layer and a reflective layer to increase reflectivity. An undercoat layer or a protective layer may be provided between the recording layer and the substrate, and each layer may have a laminated structure of two or more layers for improving the function. The structure most commonly used is a structure comprising a first substrate / organic dye layer / reflective layer / protective layer / adhesive layer / second substrate (protective substrate).

"substrate"
The substrate must be transparent to the laser used when performing recording / reproduction from the substrate side, but need not be transparent when performing recording / reproduction from the recording layer side. As the substrate material, for example, a polyester resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a polyolefin resin, a phenol resin, an epoxy resin, a polyimide resin such as a polyimide resin, glass, ceramic, metal, or the like can be used. A tracking guide groove or guide pit and a preformat such as an address signal may be formed on the surface of the substrate. As a specific example of the preformat, a land pre-pit method is used for DVD-R / RW, and a high frequency wobble method is used for DVD + R / RW. In both methods, disc information and address information are input, and the recording drive performs recording based on this information.

<Recording layer>
The recording layer causes an optical change due to the irradiation of the laser beam and records information by the change, and a material containing an organic dye as a main component is used as the material. Here, the main component means that it contains a sufficient amount of an organic dye necessary for recording and reproduction, but usually only an organic dye is used except for a small amount of additives that are appropriately added as necessary.
Examples of organic dyes include azo, formazan, dipyrromethene, (poly) methine, naphthalocyanine, phthalocyanine, tetraazaporphyrin, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (in) (Dansylene), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene, triphenothiazine dyes, or metal complexes thereof. Among these, azo (metal chelate) dye, formazan (metal chelate) dye, squarylium (metal chelate) dye, dipyrromethene (metal chelate) dye, trimethine cyanine dye, and tetraazaporphyrin dye are preferable.
As the thermal decomposition characteristics, the above dyes preferably have a decomposition start temperature of 100 to 360 ° C, particularly preferably 100 to 350 ° C. If the decomposition start temperature exceeds 360 ° C., pit formation at the time of recording is not performed well, and jitter characteristics deteriorate. Further, if the temperature is lower than 100 ° C., the storage stability of the disk deteriorates.

For the purpose of improving optical characteristics, recording sensitivity, signal characteristics, etc., the above dyes may be mixed with other organic dyes, metals, metal compounds, or a layer composed of a dye layer and other organic dyes, metals, metal compounds. May be laminated.
Examples of such metals and metal compounds include In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO ₂ , SnO, As, Cd, and the like. It can be used by laminating.
Furthermore, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone, liquid rubber, or a silane coupling agent may be dispersed and mixed in the dye, For the purpose of improving the properties, stabilizers (for example, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers and the like can be used together.

The recording layer can be formed by ordinary means such as vapor deposition, sputtering, CVD, and solvent coating. When the coating method is used, the above-described dye or the like can be dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, or spin coating. Organic solvents generally used include alcohols such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; sulfoxides such as dimethyl sulfoxide Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene; cellosolves such as methoxyethanol and ethoxyethanol; hexane and penta , Cyclohexane, and hydrocarbons such as methylcyclohexane.
The thickness of the recording layer is 100 to 10 μm, preferably 200 to 2000 μm.

<Underlayer>
The undercoat layer consists of (1) improved adhesion, (2) a barrier such as water or gas, (3) improved storage stability of the recording layer, (4) improved reflectance, and (5) a substrate from a solvent. And (6) guide grooves, guide pits, and preformats. For the purpose of (1), various polymer compounds such as ionomer resin, polyamide resin, vinyl resin, natural resin, natural polymer, silicone, liquid rubber, or a silane coupling agent can be used. For the purposes of (2) and (3), in addition to the above polymer materials, inorganic compounds such as SiO, MgF, SiO ₂ , TiO, ZnO, TiN, and SiN can be used. Furthermore, Zn, Cu Ni, Cr, Ge, Se, Au, Ag, Al, or other metals or metalloids can be used. For the purpose of (4), an organic thin film having a metallic luster made of a metal such as Al, Au, or Ag, a methine dye, a xanthene dye, or the like can be used. For the purposes (5) and (6), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used.
The thickness of the undercoat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.

<Reflective layer>
Examples of the material for the reflective layer include metals such as Au, Ag, Cr, Ni, Al, Fe, and Sn that can be obtained with a high reflectivity and are not easily corroded, but from the viewpoint of reflectivity and productivity. Au, Ag, and Al are particularly preferable. In addition, these metals and metalloids may be used alone or as two or more alloys.
Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 50 to 5000 mm, preferably 100 to 3000 mm.

《Protective layer, hard coat layer on substrate surface》
The protective layer and the hard coat layer on the substrate surface are (1) protection from scratches, dust and dirt on the recording layer (reflection / absorption layer), (2) improvement in storage stability of the recording layer (reflection / absorption layer), (3 ) Used for the purpose of improving the reflectance. For these purposes, the same material as the undercoat layer can be used. Also heat of polymethyl acrylate resin, polycarbonate resin, epoxy resin, polystyrene resin, polyester resin, cellulose resin, aliphatic hydrocarbon resin, natural rubber, styrene butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil, rosin, etc. Organic materials such as softening and heat-melting resins can also be used. The most preferable is an ultraviolet curable resin excellent in productivity.
The film thickness of the protective layer or the substrate surface hard coat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.
As in the case of the recording layer, the undercoat layer, protective layer and substrate surface hard coat layer may contain a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like. it can.

《Protective substrate》
The protective substrate must be transparent to the laser beam used when the laser beam is irradiated from the protective substrate side, but may not be transparent when used as a simple protective plate.
The protective substrate material that can be used is exactly the same as the above substrate material, such as polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide resin, or glass, ceramic, metal, etc. Can be used.
<Adhesive layer>
Any material can be used as the material for the adhesive layer as long as it can adhere two recording media. In view of productivity, an ultraviolet curable adhesive or a hot-melt adhesive is preferable.
Furthermore, in order to carry out any of the recording / reproducing methods of the present invention 1 to 3, it is desirable that information relating to the recording / reproducing method is pre-formatted in advance on the target dye-based recordable DVD medium. Specific examples of the preformat include a land pre-pit method for DVD-R / RW and a high-frequency wobble method for DVD + R / RW. In both methods, disc information and address information are input, and the recording drive performs recording based on this information.

Next, the recording / reproducing apparatus of the present invention will be described.
An optical disc is used as a device for recording large-capacity information. The optical disc is usually recorded and reproduced by an optical disc drive (recording / reproducing device). Here, an outline of the configuration of the optical disc and the optical disc drive will be described.
DVD-RAM / WO, DVD-R, DVD + R, and DVD-RAM, DVD-RW, and DVD + RW discs are writable (recordable) DVDs (Digital Versatile Discs). DVD-RAM / WO, DVD-R, and DVD + R are DVDs that can be written only once (also referred to as DVD Write Once). DVD-RAM, DVD-RW, and DVD + RW are DVDs that can be written a plurality of times. Information is recorded / reproduced on these optical discs such as DVD + R and DVD + RW discs by a drive as shown in FIG.

  FIG. 5 is a functional block diagram showing an example of the configuration of the main part of the optical disc drive. In the figure, 11 is an optical disk, 12 is a spindle motor, 13 is an optical pickup, 14 is a motor driver, 15 is a read amplifier, 16 is a servo means, 17 is a DVD decoder, 18 is an ADIP decoder, 19 is a laser controller, and 20 is a DVD. Encoder, 21 DVD-ROM encoder, 22 buffer RAM, 23 buffer manager, 24 DVD-ROM decoder, 25 API / SCSI interface, 26 D / A converter, 27 ROM, 28 CPU, 29 RAM indicates LB, laser light, and Audio indicates an audio output signal.

In FIG. 5, arrows indicate the direction in which data mainly flows, and in order to simplify the drawing, the CPU 28 that controls each block in FIG. Is omitted. The ROM 27 stores a control program written in a code readable by the CPU 28. When the optical disk drive is turned on, the program is loaded into a main memory (not shown), and the CPU 28 controls the operation of each unit according to the program and temporarily stores data necessary for the control. Is stored in the RAM 29.
The configuration and operation of the optical disk drive are as follows. The optical disk 11 is rotationally driven by a spindle motor 12. The spindle motor 12 is controlled by the motor driver 14 and the servo means 16 so that the linear velocity or the angular velocity is constant. This linear velocity or angular velocity can be changed stepwise.

The optical pickup 13 includes a semiconductor laser, an optical system, a focus actuator, a track actuator, a light receiving element, and a position sensor (not shown), and irradiates the optical disk 11 with a laser beam LB. The optical pickup 13 can be moved in the sledge direction by a seek motor. These focus actuator, track actuator, and seek motor are positioned at a target location on the optical disk 11 by the motor driver 14 and the servo means 16 based on signals obtained from the light receiving element and the position sensor. To be controlled.
At the time of reading, the reproduction signal obtained by the optical pickup 13 is amplified and binarized by the read amplifier 15 and then input to the DVD decoder 17. The input binarized data is demodulated 8/16 in the DVD decoder 17. Note that the recording data is modulated in units of 8 bits and modulated (8/16 modulation). In this modulation, 8 bits are converted to 16 bits. In this case, the combined bits are attached so that the number of previous “1” s and “0” s are equal on average. This is called “DC component suppression”, and the slice level fluctuation of the DC-cut reproduction signal is suppressed.

The demodulated data is subjected to deinterleaving and error correction. Thereafter, this data is input to the DVD-ROM decoder 24, and further error correction processing is performed in order to increase the reliability of the data. The data that has been subjected to the error correction processing twice as described above is temporarily stored in the buffer RAM 22 by the buffer manager 23, and is arranged as sector data to the host computer (not shown) via the ATAPI / SCSI interface 25. It is transferred at a stretch. In the case of music data, the data output from the DVD decoder 17 is input to the D / A converter 26 and extracted as an analog audio output signal Audio.
At the time of writing, data sent from the host computer through the ATAPI / SCSI interface 25 is temporarily stored in the buffer RAM 22 by the buffer manager 23. Thereafter, the write operation is started. In this case, it is necessary to position the laser spot at the write start point before that. In DVD + RW / + R, this point is calculated | required by the wobble signal previously carved on the optical disk 11 by the meandering of the track | truck.

Note that the above points are obtained by land pre-pits instead of wobble signals in DVD-RW / -R, and by pre-pits in DVD-RAM / RAM / WO.
The wobble signal in the DVD + RW / + R disc includes address information called ADIP (ADless In Pre-groove), and this information is extracted by the ADIP decoder 18. The synchronization signal generated by the ADIP decoder 18 is input to the DVD encoder 20 so that data can be written at an accurate position on the optical disk 11. The data in the buffer RAM 22 is subjected to error correction code addition and interleaving in the DVD-ROM encoder 21 and the DVD encoder 20, and is recorded on the optical disc 11 by the recording waveform of the present invention via the laser controller 19 and the optical pickup 13. Is done.

The recording / reproducing apparatus of the thirteenth aspect of the present invention has a simple rectangular shape in which the shortest mark and the second mark from the shortest are formed on a recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with wobbles. Recording with the wave pulse, the third and subsequent marks from the shortest are recorded with a pulse whose output is increased at the leading and trailing ends of the pulse for a certain period of time, and after the trailing edge of the pulse at the time of recording the mark A recording / reproducing method for reproducing the recording with reproducing light can be carried out with the amount of irradiation light of the cooling pulse of 0.1 mW or less for a certain time, and the recording power in the pulse of the third and subsequent marks from the shortest is P ₂ . when parts and the recording power for a certain time high output at two places of the rear end portion and P _1, P ₁ and P ₂ are characterized by having a function to satisfy the following formula (1) .
P ₁ = b × P ₂ −a × P ₂ ^{2 /} Pop (a ≧ 0.2, b ≧ 1.3) (1)
(In the formula, Pop represents the P ₂ value at the time of optimum recording on the medium.)
Thereby, high quality recording at a high linear velocity can be realized.

Further, the recording / reproducing apparatus of the present invention 14 has a function of setting the time for irradiating the cooling pulse after the rear end of the pulse to 1/6 to 6/6 of the re-short space, so that the recording quality is further improved. Can be improved.
Furthermore, the recording / reproducing apparatus according to the fifteenth aspect of the present invention determines the pulse width and head heating pulse width of a recording pulse that forms a mark having the shortest space length immediately before by determining whether or not the mark length is the shortest length. Distinguish, set the pulse width of the shortest length mark longer than the leading heating pulse width of the mark that is not the shortest length, and the pulse width of the recording pulse that forms the shortest length mark is the space length immediately before the shortest length mark. High quality because it has the function to set the pulse width of the mark whose previous space length is the shortest length shorter than the pulse width of the mark whose previous space length is not the shortest length. Recording, that is, low jitter can be realized.
The method for obtaining address information may be a method for obtaining address information from land prepits or prepits.

FIG. 6 is a schematic diagram of an information processing apparatus using the optical disk drive shown in FIG.
The information processing apparatus includes a main control device, an interface, a recording device, an input device, a display device, and the like.
The main controller includes a CPU (central processing unit, microcomputer), a main memory (none of which are shown), and the like, and controls the entire host computer.
The interface is a two-way communication interface with the optical disc drive, and conforms to standard interfaces such as ATAPI and SCSI. The interface is connected to the optical disk drive interface 25 described above. The connection form between the interfaces may be not only a cable connection using a communication line such as a communication cable (for example, a SCSI cable) but also a wireless connection using infrared rays.

The recording device (HDD, hard disk) stores a program written in a code readable by the microcomputer of the main control device. When the information processing apparatus is powered on, the program is loaded into the main memory of the main control apparatus.
The display device includes a display unit (not shown) such as a CRT, a liquid crystal display (LCD), or a plasma display panel (PDP), and displays various information from the control device.
The input device includes at least one input medium (not shown) such as a keyboard, a mouse, and a pointing device, for example, and notifies the main control device of various information input by the user. Note that information from the input medium may be input in a wireless manner. Further, as an integrated display device and input device, there is a CRT with a touch panel, for example. The information processing apparatus is equipped with an operating system (OS). It is assumed that all devices constituting the information processing apparatus are managed by the OS.

  According to the present invention, it is possible to efficiently improve the recording power margin (allowable recording power width) of recording characteristics such as jitter and error at any linear velocity with respect to the dye-based recordable DVD medium. Deployment is also easy. Moreover, recording is possible on a dye-based recordable DVD medium having almost the same format as CD-R and CD-RW currently manufactured in large quantities.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by these Examples.

Examples 1-3, Comparative Example 1
The following [Chemical Formula 1] and [Chemical Formula 2] are formed on an injection molded polycarbonate substrate having a groove depth of 1670 mm, a half width of 0.39 μm, a track pitch of 0.74 μm, a thickness of 0.6 mm corresponding to a wobble frequency of 32T, and an outer diameter of 120 mm. The pigment compound was weighed 75:25 by weight, dissolved in 2,2,3,3-tetrafluoro-1-propanol and applied with a spinner to form an organic pigment layer having a thickness of 750 mm, and then at 90 ° C. Dry for 30 minutes.
Next, an Ag reflective layer having a thickness of 1100 mm is provided by sputtering, and a protective layer having a thickness of 5 μm made of an acrylic photopolymer is provided thereon, and then an injection molded polycarbonate having a thickness of 0.6 mm and an outer diameter of 120 mm. An optical recording medium was obtained by bonding the flat substrate with an acrylic photopolymer.

<Recording and playback conditions>
For the optical recording medium, a semiconductor laser beam having an oscillation wavelength of 660 nm and a beam diameter of 0.9 μm is used, and the recording powers P ₁ and P ₂ are changed so as to satisfy the expression (1) of the present invention 1 while tracking. , EFM signal (minimum pit length of about 0.4 microns) was recorded.
As shown in Table 2, the result when P ₁ / P _2, which is a recording power setting that is normally used, is constant (a = 0) was set as Comparative Example 1, and the value of a was changed and b was optimized for recording. The case was made into Examples 1-3. The waveform of the recording laser beam was as shown in FIG. P ₂ is therefore dependent on the optical recording medium and a recording and reproducing apparatus, the jitter value was set to the recording power becomes minimum (optimum recording power). Also set _{P 0} and _{P 1} to the same value, and the irradiation light amount of the cooling pulse and 0.0MW. The recording linear velocity at the time of evaluation was 41.9 m / s (12 × recording). The Pop value at that time was 20 mW.
FIG. 7 shows the measurement results of the recording characteristics (jitter and asymmetry). In Examples 1 to 3, the recording power margin (allowable recording power) is improved as compared with Comparative Example 1 of the prior art. It could be confirmed. Here, the asymmetry is a parameter indicating a recording state. When recording is performed with a high recording power, the asymmetry value is also increased.

Example 4, Comparative Examples 2-3
The recording characteristics were evaluated in the same manner as in Example 2 except that the irradiation light quantity (power) of the cooling pulse was changed. The jitter value at the optimum recording power is shown in Table 3 together with the case of Example 2. As compared with Examples 2 and 4 in which the cooling pulse power is 0.0 mW and 0.1 mW, 0.2 mW and 0. In Comparative Examples 2 and 3 having 7 mW, it can be seen that the characteristics are deteriorated.

Example 5
Except that the value of b was changed, 12x recording was performed in the same manner as in Example 1 (that is, a = 0.2), and the jitter at that time was measured.
The results are shown in Table 4. The medium 1 is a Ricoh DVD + R, the medium 2 is a TDK DVD + R, the medium 3 is a Fuji Photo Film DVD-R, and the medium 4 is a Litec DVD + R. The values in Table 4 are jitter values when recording is performed with the optimum recording power.
As can be seen from Table 4, the optimum b value varies depending on the medium, but the jitter value is minimized when b is 1.3 or more.

(A)-(d) The figure which shows the example of a layer structure of a normal write-once type optical recording medium. (A)-(c) The figure which shows the example of a layer structure of a normal CD-R medium. (A)-(c) The figure which shows the layer structural example of a pigment | dye type recordable DVD medium. FIG. 6 is a diagram illustrating an example of a recording power control waveform corresponding to the first embodiment. The functional block diagram which shows an example of the principal part structure of an optical disk drive. 6 is a schematic diagram of an information processing apparatus using the optical disk drive shown in FIG. The figure which shows the measurement result of Examples 1-3 and the comparative example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Undercoat layer 4 Protective layer 5 Hard coat layer 6 Reflective layer 7 Protective substrate 8 Adhesive layer space: Space mark: Mark Cooling Area: Cooling area T: Basic clock period n: Integer greater than or equal to n n: Integer of 3 or more ps: Space length immediately before cm: Recording mark length P ₀ : Recording power of the shortest mark P ₁ : Power with addition of the third from the shortest P ₂ : Power without addition of the third from the shortest

Claims (16)

The shortest mark and the second mark from the shortest are recorded with a simple rectangular wave pulse on the recording layer mainly composed of an organic dye formed on the substrate having the guide groove, and the third and subsequent marks from the shortest are recorded. The mark is recorded with a pulse whose output is increased for a certain period of time at the front end and the rear end of the pulse, and the irradiation light quantity of the cooling pulse after the rear end of the pulse during the mark recording is 0.1 mW or less for a certain period of time. In the recording / reproducing method for reproducing the recording with the reproducing light, the recording power in the pulse of the third and subsequent marks from the shortest is P ₂ , and the recording power is increased for a certain period of time at two positions, the front end and the rear end. A recording / reproducing method for a dye-based recordable DVD medium, wherein P ₁ and P ₂ satisfy the following formula (1) when the power is P ₁ .
P ₁ = b × P ₂ −a × P ₂ ^{2 /} Pop (a ≧ 0.2, b ≧ 1.3) (1)
(In the formula, Pop represents the P ₂ value at the time of optimum recording on the medium.)   2. The recording / reproducing method according to claim 1, wherein a time for irradiating the cooling pulse after the rear end of the pulse is set to a length of 1/6 to 6/6 of the shortest long space.   The pulse width of the recording pulse that forms the mark with the shortest space length immediately before and the head heating pulse width are distinguished by whether or not the mark length is the shortest length, and the pulse width of the shortest mark is the shortest. Set longer than the leading heating pulse width of the mark that is not long, and distinguish the pulse width of the recording pulse that forms the shortest length mark according to whether the space length immediately before the shortest length mark is the shortest length, 3. The recording / reproducing method according to claim 1, wherein the pulse width of the mark having the shortest immediately preceding space length is set shorter than the pulse width of the mark having the immediately preceding space length not having the shortest length.   4. The recording / reproducing method according to claim 1, wherein the wobble frequency is a frequency corresponding to 4T to 96T, where T is a basic clock period.   The ratio “Wo / PP” between the wobble amplitude (Wo) and the push-pull amplitude (PP) of the track error detection signal for detecting and controlling the track error by the two-divided photodetector is 0.1 ≦ Wo / PP ≦ 5. The recording / reproducing method according to claim 1, wherein synchronization is performed within a range of 0.4.   6. The recording / reproducing method according to claim 1, wherein the wavelength of the recording light is 600 to 720 nm.   The recording layer single layer has a refractive index n of 1.5 ≦ n ≦ 3.0 and an extinction coefficient k of 0.02 ≦ k ≦ with respect to the light in the wavelength range of the recording light and the reproducing light of ± 5 nm. The recording / reproducing method according to claim 1, wherein the recording / reproducing method is 0.2.   The recording / reproducing method according to claim 1, wherein the decomposition start temperature of the recording layer is 100 to 360 ° C.   An optical recording medium has at least one layer selected from a reflective layer, a protective layer, an adhesive layer, a protective substrate, and a substrate surface hard coat layer as a constituent layer other than the recording layer on a substrate having a guide groove provided with a wobble. The recording / reproducing method according to claim 1, wherein the recording / reproducing method is provided.   10. The recording / reproducing method according to claim 9, wherein the reflective layer is any one of gold, silver, and aluminum, or an alloy containing them as a main component.   11. The recording / reproducing method according to claim 9, wherein the protective layer is made of an ultraviolet curable resin.   An adhesive layer for bonding two substrates to form a double-sided recording medium is provided between the substrates, and the adhesive used for the adhesive layer is an ultraviolet curable resin. The recording / reproducing method according to any one of 9 to 11. The shortest mark and the second mark from the shortest are recorded with a simple rectangular wave pulse on the recording layer mainly composed of an organic dye formed on the substrate having the guide groove, and the third and subsequent marks from the shortest are recorded. The mark is recorded with a pulse whose output is increased for a certain period of time at the front end and the rear end of the pulse, and the irradiation light quantity of the cooling pulse after the rear end of the pulse during the mark recording is 0.1 mW or less for a certain period of time. The recording / reproducing method for reproducing the recording with the reproducing light can be carried out, and the recording power in the pulse of the third and subsequent marks from the shortest is P ₂ , and the output is high for a certain period of time at two positions, the front end and the rear end when a recording power that is of the P _1, the recording and reproducing apparatus of the dye-based recordable DVD medium which P ₁ and P ₂ are characterized by having a function to satisfy the following equation (1).
P ₁ = b × P ₂ −a × P ₂ ^{2 /} Pop (a ≧ 0.2, b ≧ 1.3) (1)
(In the formula, Pop represents the P ₂ value at the time of optimum recording on the medium.)   14. The recording / reproducing apparatus according to claim 13, wherein the time for irradiating the cooling pulse after the rear end of the pulse has a function of setting the length to 1/6 to 6/6 of the shortest long space.   The pulse width of the recording pulse that forms the mark with the shortest space length immediately before and the head heating pulse width are distinguished by whether or not the mark length is the shortest length, and the pulse width of the shortest mark is the shortest. Set longer than the leading heating pulse width of the mark that is not long, and distinguish the pulse width of the recording pulse that forms the shortest length mark according to whether the space length immediately before the shortest length mark is the shortest length, 15. A recording / reproducing apparatus according to claim 13, wherein the recording / reproducing apparatus has a function of setting a pulse width of a mark whose preceding space length is the shortest length shorter than a pulse width of a mark whose preceding space length is not the shortest length. . 4. A dye-based recordable DVD medium, wherein information for performing the recording / reproducing method according to claim 1 is preformatted in advance.