JP4322782B2 - Dye-type recordable DVD medium recording / reproducing method and apparatus - Google Patents

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 reflectance in a recording layer, and can additionally record 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. To increase the speed, it is necessary to increase the output of the recording laser, increase the sensitivity of the recording material, the recording method, the optimization of the recording waveform, and the like. Elemental technologies for improving the recording capacity include the development of recording materials for miniaturization of recording pits, the use of image compression technology represented by MPEG2, and the shortening of the wavelength of semiconductor lasers for reading recording pits. is necessary.
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 recording pulse width and recording power due to 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 heating pulse necessary to form the mark, the heating temperature that reaches the optimum decomposition temperature is different, the average length of the mark varies, and the duty ratio of the optimum heating pulse is different. The uniform mark width cannot be obtained, and the thickness and the thickness are reduced depending on the mark length, so that the jitter characteristic is deteriorated.
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.

  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 that use multi-pulse recording by using a dye are known, but as far as the present inventors know, 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 of 42 m / s or more.

An object of the present invention is to provide an optical recording / reproducing method and apparatus capable of obtaining a good recording waveform even when high linear velocity recording of 42 m / s or more is performed on a dye-based recordable DVD medium.
Further, the present invention is a new format system of a write-once DVD system using a semiconductor laser having an oscillation wavelength shorter than that of a CD-type medium, and eliminates an unrecorded area in a data write-in portion as in the LPP system. Compared with the DVD-R land pre-pit method, an effective method provides an excellent method that does not cause data errors due to fine cut width control and leakage of the LPP signal to the data part during stamper production. With the goal.

The above problems are solved by the following inventions 1) to 15) (hereinafter referred to as the present inventions 1 to 15).
1) The shortest mark is recorded with one pulse light whose rear end portion has a high output on a recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble, A mark having the second and subsequent lengths from the shortest is output with a high power for at least the rear end of the front end and rear end of the pulse for a certain period of time, and the increased pulse power is the front end of the shortest length mark. When recording with one pulse light equal to the pulse power of the above and reproducing the recording with reproduction light, at the time of recording the mark, a cooling pulse is irradiated after the trailing edge of the pulse of all the marks, and the irradiation light quantity For a predetermined time of 0.1 mW or less, and a recording linear velocity of 42 to 56 m / s .
2) The time for irradiating the cooling pulse at the rear end portion after the pulse, 1, characterized in that the length of 1 / 6-6 / 6 of the shortest space) record reproducing method according.
3) The heating pulse width of the recording pulse that forms the mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is the shortest length. The heating pulse width of the recording pulse that is set longer than the heating pulse width of the non-mark and forms the shortest length mark is distinguished by whether or not the space length immediately before the shortest length mark is the shortest length. the heating pulse width of a mark space length is the shortest, 1 space length immediately before and setting shorter than the heating pulse width of a mark is not the shortest) or 2) record reproducing method according.
4) frequency of the wobble is record reproduction method according to any one of 1) to 3), characterized in that the 4T~96T corresponding basic clock cycle as T.
5) The ratio “Wo / PP” between the amplitude (Wo) of the wobble and the push-pull amplitude (PP) which is a difference signal by the two-divided photodetector for detecting and controlling the track error is set to 0.1 ≦ Wo record reproduction method according to any one of 1) to 4), characterized in that the combined synchronized as a range of /PP≦0.4.
6) record reproduction method according to any one of 1) to 5), wherein the wavelength of the recording light is 600～720Nm.
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 the light in the wavelength range of the recording light and reproducing light wavelength ± 5 nm. record reproduction method according to any one of 1) to 6), which is a k ≦ 0.2.
8) record reproduction method according to any one of 1) to 7), wherein the decomposition temperature of the recording layer is 100-360 ° C..
9) The dye-based recordable DVD medium has on the substrate 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. record reproduction method according to any one of 1) to 8), wherein.
10) dye-based recordable DVD medium has a reflective layer, the reflective layer is gold, silver, or aluminum, or they, characterized in that an alloy composed mainly 9), wherein the record Playback method.
11) dye-based recordable DVD medium has a protective layer, 9 the protective layer is characterized by comprising the ultraviolet-curing resin) or 10) record reproducing method according.
12) A structure in which a dye-based recordable DVD medium has at least a recording layer, a reflective layer, and a protective layer on a substrate having a guide groove provided with a wobble, and further has a protective substrate via an adhesive layer (single layer type) Alternatively, a structure in which two sets of structural units each having at least a recording layer, a reflective layer, and a protective layer are bonded on a substrate having a guide groove provided with a wobble so that the substrate is disposed outside via an adhesive layer (two layers). is the type), record reproduction method according to any one of 9) to 11), wherein the adhesive used in the adhesive layer is an ultraviolet curable resin.
13) A recording / reproducing apparatus including at least a spindle motor, an optical pickup, a motor driver, and a laser controller, and a recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble. The shortest length mark is recorded with one pulse light whose rear end portion has a higher output, and the second and subsequent length marks from the shorter side are recorded with at least the rear end portion of the front end portion and the rear end portion of the pulse. When a high power is output for a certain time, the high output pulse power is recorded with a single pulse light equal to the pulse power at the tip of the shortest mark, and when the recording is reproduced with the reproduction light, The cooling pulse is irradiated after the trailing edge of the pulse of all the marks, the irradiation light quantity is set to 0.1 mW or less for a certain time, and the recording linear velocity is set to 42 to 56 m / s . A recording / reproducing apparatus for a dye-based recordable DVD medium having a function.
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 heating pulse width of the recording pulse forming the mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is the shortest length. The heating pulse width of the recording pulse that is set longer than the heating pulse width of the non-mark and forms the shortest length mark is distinguished by whether or not the space length immediately before the shortest length mark is the shortest length. The recording / reproducing apparatus according to 13) or 14), which has a function of setting the heating pulse width of the mark having the shortest space length shorter than the heating pulse width of the mark having the shortest space length.

Hereinafter, the present invention will be described in detail.
In the first to third embodiments, the basic optimum recording pulse irradiation pattern is defined.
In the present invention, improvement in recording quality in high linear velocity recording of 42 m / s or more is an important issue, but in high linear velocity recording, how the shortest length mark is uniformly formed greatly affects the recording quality. As a result, when the recording linear velocity is 8X (28 m / s) or 10X (35 m / s), good recording quality can be maintained even if the pulse forming the shortest mark is a simple rectangular wave. It was found that sufficient recording quality could not be obtained when the recording linear velocity was 12X (42 m / s) or higher.
In order to solve this problem, the present invention aims to improve the quality of the shortest length mark by increasing the output of the rear end portion of the pulse forming the shortest length mark higher than the pulses of other marks. In addition, when forming a mark having the second and subsequent lengths from the shortest, the jitter can be improved by increasing the output of the tip of the pulse, but at least the pulse asymmetry is improved for the purpose of the present invention. It is necessary to increase the output of the rear end. That is, for both the second and subsequent length marks from the shortest, if both the leading edge and trailing edge of the pulse are increased in output, both jitter and asymmetry can be improved moderately, and if only the trailing edge is increased, Mainly contributes to the improvement of low asymmetry.

As for the length of the second and subsequent lengths from the shortest side, that is, the mark other than the shortest length mark, the power is increased by adding power only to the leading edge and the trailing edge or the trailing edge of the pulse. A range of 0.5 to 2 times the basic clock period T, that is, a range of 0.5T to 2T is particularly preferable, and a range of 0.2T to 2.5T is also possible. In addition, the length for increasing the output by adding power to the rear end of the pulse of the shortest mark is particularly preferably in the range of 0.3T to 1.5T, and also in the range of 0.2T to 2.0T. Is possible.
In addition, the amount of light at the rear end of the pulse forming the shortest length mark is larger than the amount of light at the top of the pulse forming the other mark, and the light amount of the tip of the pulse forming the shortest length mark, It is essential that the amount of light added on the pulses forming the other marks is equal, and the pulse power at the rear end of the shortest mark is increased, and the pulse power at the tip of the shortest mark is 2 W0 / W1 where W1 is the pulse power that is increased by adding the leading end or the rear end of the second and subsequent marks, and W2 is the non-addition pulse power that is the second and subsequent lengths from the shorter one. = 1.01 to 2.00 can be employed, but preferably 1.02 to 1.50. On the other hand, W1 / W2 can be employed in the range of 1.05 to 3.00, but is preferably in the range of 1.08 to 2.00.

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. It is physically impossible to exceed 6/6 because the cooling area may exceed the shortest space and reach the next mark. Further, if there is no cooling pulse, waveform interference occurs due to the residual heat (residual heat) effect, and jitter deteriorates. Even if the cooling is too short, the jitter is almost the same as when there is no cooling pulse. Specifically, in a certain medium, the jitter is 7.0% when recording with an optimum waveform at 42 m / s in clean 6/6, and when the irradiation time is changed, the following is performed. . That is, 1/6 is a preferred lower limit because the degree of jitter deterioration increases from 1/6.
Irradiation time Jitter Asymmetry PI error
5/6 ... 7.1% 0.01 6
4/6 ... 7.2% 0.01 6
3/6 ... 7.4% 0.01 7
2/6 ... 7.4% 0.01 8
1/6 ... 7.5% -0.01 14
0.5 / 6 ... 7.5 -0.05 24
0/6 ... 7.7% -0.08 47

By selecting the pulse waveform as described above, it is possible to perform good recording with low jitter, particularly in high linear velocity recording of 42 m / s or more.
The dye-based optical recording medium has to increase the recording power in order to achieve a higher linear velocity, and as a result, thermal interference between marks is more likely to occur. Therefore, the present invention is effective to improve the mark edge breakage when forming the mark.
When recording is performed with the conventional example, the recording power that obtains the lowest jitter and the recording power that minimizes the error are shifted to reduce the power margin. Specifically, in high linear velocity recording, the asymmetry of the recording signal tends to be negative at the recording power at which the lowest jitter is obtained, and in error measurement, errors are likely to occur even though the jitter is low. For example, even if the asymmetry is negative, low jitter, and low error, errors are more likely to occur than media recorded near zero asymmetry due to aging of the medium and drive. The present invention has been made to solve this low asymmetry problem.

In addition, even when writing one mark with a plurality of pulse lights (multi-pulse), if the pulse light is optimized, the above-mentioned low asymmetry problem can be solved. When the rise and fall times of light vary, the recording quality itself may vary. Needless to say, this variation is more likely to occur as the linear velocity is recorded.
On the other hand, in the present invention, since recording is performed with one pulse of light per mark, there is an advantage that a recording method with less variation in recording quality can be provided as compared with the multi-pulse light recording. In addition, the address detection during writing has a simpler recording waveform than the multi-pulse method, so the amount of light during recording is easy to average, and not only the amount of reflected light in the space portion but also the amount of light in the mark portion is averaged for address detection. Therefore, even if a cooling pulse of 0.1 mW or less is provided at the rear end of the pulse, there is an advantage that address detection can be performed relatively easily.

An example of the recording pulse waveform corresponding to the first to third aspects of the present invention is shown in FIGS. 4 to 7. In this case, the rear end portion of the pulse of the shortest length mark is increased in output, and the second and subsequent ones from the shortest one are increased. The high output level of the long mark pulse is equal to the tip of the shortest mark pulse.
Considering the influence of thermal interference, the heating pulse width of the recording pulse for forming the mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length. The heating pulse width of the long mark is set to be longer than the heating pulse width of the mark that is not the shortest length (see, for example, the case where the immediately preceding space length is 3T and the recording mark length is 3T, 4T to 14T in Table 1 described later). Thus, recording with lower jitter can be realized.
Further, the heating 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 heating pulse width of the mark having the shortest space length immediately before is short. Is set to be shorter than the heating pulse width of the mark whose preceding space length is not the shortest (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). Low jitter recording can be realized.

The correction amount (length) for setting the 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 heating pulse width of the pulse forming the mark is substantially equal to the case of the other marks, the space length immediately before is shortened due to thermal interference, Jitter slightly deteriorates. Therefore, only in such a case, it is effective to shorten the heating pulse width for recording the mark. Needless to say, it is effective to shorten the front edge of the heating pulse in order to further shorten the pulse width.
In addition, when the space length immediately before the mark to be formed is the shortest length, it is not preferable that the heating pulse width of the pulse for forming the mark is shorter than 0.10 T because the mark length itself becomes too short.
The correction amount (length) when the heating 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 heating pulse width of the shortest length mark is increased by correcting within the above range.

Specific examples of the correction amount of the 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 ± 5 nm of the recording light and reproducing light 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.
Normally, the wobble frequency band corresponding to 150T to 400T is used, but this frequency band is too low when writing data, whether it is frequency modulation or phase modulation, and the previous data Is not suitable for high-density recording. 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 Invention 5, the preferred frequency of 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 a gap is too wide at the seam when data is additionally written, causing problems such as a reduction in capacity and a reduction in data processing speed.

The wobble amplitude of the DVD medium to which the present invention is applied is the wobble amplitude (Wo) of the signal passing through a suitable filter, for example, 4 MHz, 30 kHz, and a suitable filter, for example, a 30 kHz filter. As long as the ratio Wo / PP of the push-pull signal (PP) satisfies 0.1 ≦ Wo / PP ≦ 0.4, synchronization with the wobble that is the object of the present invention is easy, More 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 (a single-layer medium having one recording layer).
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).
Further, if necessary, for example, two sets of layer constitution units excluding the protective substrate from the layer constitution shown in FIGS. 3B and 3C are prepared, and the substrate is placed outside via the adhesive layer ( A laminated structure (a two-layer medium having two recording layers) may be used so that the recording layer is on the inner side.

"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.

<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 them, 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.

Next, the recording / reproducing apparatus of the present invention will be described. Inventions 13 to 15 are recording / reproducing apparatuses having a function capable of recording / reproducing a dye-based recordable DVD medium by the recording / reproducing methods of the inventions 1 to 3, respectively.
An optical disc is used as a medium for recording large-capacity information, and the optical disc is usually recorded and reproduced by an optical disc drive (recording / reproducing apparatus). 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 and reproduced on these optical discs such as DVD + R and DVD + RW discs by a drive as shown in FIG.

  FIG. 8 is a functional block diagram showing an example of a main part configuration of the optical disk 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. 8, the arrows indicate the direction in which data mainly flows. 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 (not shown), an optical system, a focus actuator, a track actuator, a light receiving element, and a position sensor, 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 into 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 in the state of being host data (not shown) via the ATAPI / SCSI interface 25. )) At once. 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.
Further, the address information may be obtained by using a land pre-pit or a pre-pit.

FIG. 9 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 types of information from the control device.
The input device includes, for example, at least one input medium (not shown) such as a keyboard, a mouse, and a pointing device, 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, recording with a low jitter and a low error rate can be performed on a dye-based recordable DVD medium even at a high recording linear velocity of 42 m / s or more, which is higher than the land pre-pit format used in DVD-R. In addition, the data section can be efficiently written in a high-frequency wobble format that can be easily manufactured. In addition, recording can be performed on a dye-based recordable DVD medium having almost the same format as CD-R and CD-RW that are 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 1-9, Comparative Examples 1-10
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 at a weight ratio of 70:30, 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>
A semiconductor laser beam having an oscillation wavelength of 660 nm and a beam diameter of 0.9 μm is used for the above optical recording medium, and an EFM signal (minimum pit length of about 0.4 μm) is recorded while tracking the recording conditions and recording lines shown in Table 2 below. Recording was performed at a recording power that minimizes Bottom Jitter (bottom jitter) at a high speed, and the portion was reproduced to determine the jitter value, asymmetry, and number of PI errors. The waveform of the recording laser beam is as shown in FIGS. W0 is the pulse power at the rear end of the shortest length mark, W1 is the pulse power at the front end of the shortest length mark, or the pulse power added on the mark with the second and subsequent lengths from the shorter one, and W2 is from the shorter side. This is the pulse power with no extra mark of the second and subsequent lengths. Furthermore, although the pulse lengths shown in FIGS. 4 to 7 were used in the case of linear speeds of 56 m / s and 42 m / s, the present invention is not limited to this.
In Comparative Example 1, the light amount of the cooling unit was set to 0.7 mW, which was the same as the reproduction light power. That is, the pulse waveform has no cooling pulse. In Comparative Example 2, the light quantity of the cooling part was 0.3 mW, and in Comparative Examples 4 to 7, the light quantity of the cooling part was 0.2 mW, which was larger than that of the present invention. In Comparative Example 3, as in Comparative Example 1, the recording linear velocity was set to a high linear velocity without a cooling pulse. In the comparative example 8, the entire shortest length mark whose rear end portion is not increased in output is recorded with the pulse light of W1, and in the comparative example 9, the second and subsequent length marks from the shortest side are recorded as the leading end portion. The whole of which the rear end was not increased in output was recorded with W1 pulsed light. In Example 8, the cooling pulse length was 0.4T, which was shorter than 1/6 of the shortest space length 3T of the present invention, that is, 0.5T.

上記表２から分るように、実施例１〜８は、比較例１〜９に比べて、ジッタ、アシンメトリ共に概ね良好であり、ＰＩエラーは非常に優れている。また、比較例４〜７は、クーリングパルスが０．２ｍＷであるため、ジッタは良好であるが、アシンメトリ、ＰＩエラーが悪化する。

As can be seen from Table 2 above, in Examples 1-8, both jitter and asymmetry are generally better than in Comparative Examples 1-9, and the PI error is very good. In Comparative Examples 4 to 7, since the cooling pulse is 0.2 mW, jitter is good, but asymmetry and PI error are deteriorated.

上記表３から分るように、ＬＰＰフォーマットのサンプルでは、ＬＰＰｂが大きくなると、ジッタが良好であってもＰＩエラーが増加してしまう。また、比較例１０のようにＬＰＰｂが０．１６を下回るレベルであると実用されている装置でのアドレス検出が不可能となってしまうことが確認された。 Further, 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 an EFM signal (minimum pit length of about 0.4 μm) is recorded and recorded as shown in Table 3 below while tracking. Recording was performed with a recording power at which the bottom jitter was minimized under the conditions of linear velocity and correction shown in Table 1, and the portion was reproduced to determine the jitter value, asymmetry, and number of PI errors.
In Comparative Examples 10 to 11, using the production condition stamper and the molded substrate in which the size of the LPPb in the LPP format implemented in the DVD-R was changed (changed), the production conditions were the same as in the example. An optical recording medium was prepared and evaluated in the same manner as in the examples.

As can be seen from Table 3 above, in the LPP format sample, when LPPb increases, PI error increases even if the jitter is good. In addition, it was confirmed that the address detection could not be performed with a practical device when the LPPb was below 0.16 as in Comparative Example 10.

(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. The figure which shows the example of the power control waveform applicable to this invention for recording linear velocity 42m / s. The figure which shows the example of the power control waveform applicable to this invention for recording linear velocity 42m / s. The figure which shows the example of the power control waveform applicable to this invention for 56 m / s of recording linear velocities. The figure which shows the example of the power control waveform applicable to this invention for 56 m / s of recording linear velocities. The functional block diagram which shows an example of the principal part structure of an optical disk drive. FIG. 9 is a schematic diagram of an information processing apparatus using the optical disc drive shown in 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 An integer greater than or equal to n 'An integer greater than or equal to 3 ps Space length of cm cm Recording mark length W0 Higher output pulse power at the rear end of the shortest length mark W1 Pulse power at the front end of the shortest length mark, or a pulse on top of the second and subsequent lengths of the shortest mark Power W2 Pulse power without additional mark of the second and subsequent lengths from the shortest

Claims (15)

The shortest mark is recorded on the recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble, with one pulse light whose rear end portion has a high output, and the shorter one From the leading edge and trailing edge of the pulse, at least the trailing edge of the mark having the second and subsequent lengths is increased in power for a certain period of time, and the increased pulse power is applied to the pulse at the leading edge of the shortest mark. When recording with one pulse light equal to the power and reproducing the recording with the reproduction light, at the time of recording the mark, a cooling pulse is irradiated after the rear end of the pulse of all the marks, and the irradiation light quantity is constant. A recording / reproducing method for a dye-based recordable DVD medium, characterized in that the time is 0.1 mW or less and the recording linear velocity is 42 to 56 m / s . Record reproduction method according to claim 1, wherein the time for irradiating the cooling pulse at the rear end portion subsequent pulse, the length of 1 / 6-6 / 6 of the shortest space. The heating pulse width of the recording pulse that forms the mark with the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is not the shortest length mark. The heating pulse width of the recording pulse for forming the shortest length mark is distinguished by whether or not the space length immediately before the shortest mark is the shortest length. record reproduction method according to claim 1 or 2, wherein the length is a heating pulse width of a mark which is the shortest, the space length immediately before is set shorter than the heating pulse width of a mark is not the shortest. Frequency of the wobble is record reproduction method according to claim 1, characterized in that the 4T~96T corresponding basic clock cycle as T. The ratio “Wo / PP” between the amplitude (Wo) of the wobble and the push-pull amplitude (PP) that is a difference signal by the two-divided photodetector for detecting and controlling the track error is 0.1 ≦ Wo / PP record reproduction method according to claim 1, characterized in that the combined synchronized as the range of ≦ 0.4. Record reproduction method according to claim 1, the wavelength of the recording light is characterized in that it is a 600～720Nm. 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. record reproduction method according to claim 1, characterized in that 0.2. Record reproduction method according to claim 1, wherein the decomposition temperature of the recording layer is 100-360 ° C.. The dye-based write-once DVD 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 the substrate. record reproduction method according to any one of claims 1 to 8. Dye-based recordable DVD medium has a reflective layer, the reflective layer is gold, silver, or aluminum, or record according to claim 9, wherein them, characterized in that it consists of an alloy mainly play Method. Dye-based recordable DVD medium has a protective layer, record reproduction method according to claim 9 or 10, wherein the protective layer is characterized by comprising the ultraviolet-curing resin. A structure in which a dye-based recordable DVD medium has at least a recording layer, a reflective layer, and a protective layer on a substrate having a guide groove provided with a wobble, and further has a protective substrate via an adhesive layer (single layer type), or A structure in which two sets of structural units each having at least a recording layer, a reflective layer, and a protective layer are bonded to a substrate having a guide groove provided with a wobble so that the substrate faces outside via an adhesive layer (two-layer type) , and the record reproduction method according to claim 9-11 adhesive used adhesive layer is characterized in that it is a UV-curable resin. A recording / reproducing apparatus including at least a spindle motor, an optical pickup, a motor driver, and a laser controller, which has the shortest length for a recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble. The mark is recorded with one pulse light whose rear end portion has a high output, and the second and subsequent lengths of the shortest mark are recorded for at least the rear end portion of the front end portion and the rear end portion of the pulse for a certain period of time. The output is increased, and the increased output is recorded with one pulse light equal to the pulse power at the tip of the shortest mark, and when the recording is reproduced with the reproduction light, the mark recording A function of irradiating a cooling pulse after the trailing edge of all the mark pulses, setting the irradiation light amount to 0.1 mW or less for a certain time, and setting the recording linear velocity to 42 to 56 m / s. A recording / reproducing apparatus for a dye-based recordable DVD medium, comprising:   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 heating pulse width of the recording pulse that forms the mark with the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, and the heating pulse width of the shortest mark is not the shortest length mark. And the heating pulse width of the recording pulse for forming the shortest length mark is distinguished by whether or not the space length immediately before the shortest mark is the shortest length. 15. The recording / reproducing apparatus according to claim 13, wherein the recording / reproducing apparatus has a function of setting a heating pulse width of a mark having the shortest length shorter than a heating pulse width of a mark having a shortest preceding space length.

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