JP2004303401A - Device and method to optically record and reproduce dyestuff draw type dvd medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optically recording and reproducing method of a dyestuff DRAW type DVD medium in which good recording waveforms are obtained while conducting high linear velocity recording. <P>SOLUTION: In the optically recording and reproducing method of the medium, marks other than a shortest mark, whose pulse is made of higher power than other mark pulses, are recorded by one pulse light beam, in which high power is applied to only a pulse back end section or a pulse leading section and the back end section for a certain duration, for a recording layer which is formed on a substrate having a guide groove with wobble and has organic dyestuff as a major component. When reproducing is to be conducted for the recorded information by reproducing light beams, irradiated light quantity of cooling pulses after the pulse back end sections of all marks is set to be equal to or less than 0.1mW for a certain duration during mark recording. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical recording / reproducing method and apparatus for a dye-based write-once DVD medium.

At present, high speed development of DVD ± R as a large capacity optical disk is being promoted. To increase the speed, it is necessary to increase the output of the recording laser, increase the sensitivity of the recording material, optimize the recording method, and the recording waveform. The elemental technologies for improving the recording capacity include the development of recording materials for miniaturizing recording pits, the adoption 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 band 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 using laser diodes of two wavelength bands of a 635 nm band and a 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.

Generally, in a dye-based write-once DVD medium in which pits (marks) are formed in a heat mode, the pulse width and recording power of a recording pulse train due to laser emission during recording are optimized at a specific recording speed, and different recording lines are used. The speed changes the state of marks and spaces formed. That is, the heat capacity becomes insufficient due to the head heating pulse necessary for forming the mark, the heating temperature reached for the optimal decomposition temperature varies, the average length of the mark varies, and the duty ratio of the optimal heating pulse varies. As a result, a uniform mark width cannot be obtained, and thickening or thinning occurs depending on the mark length, thus deteriorating jitter characteristics.
In the case of a DVD-R medium, the physical format of a DVD medium is standardized by a format called a land prepit in which a part of a land portion is cut. With this method, 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. If it exceeds 0.32, the LPP signal itself behaves like a noise in the data area. And many data errors occur. Therefore, in the LPP, the cut width suitable for the recording material must be finely adjusted with a stamper to control the land cut width so that LPPb is in the range of 0.16 to 0.32.

  Known examples of the optical recording medium using a dye for the recording layer include those using a polymethine dye or a polymethine dye and a light stabilizer as a recording material, a tetraazaporphyrin (porphyrazine) dye or a cyanine dye + azo metal chelate. Using a layer composed of a dye (salt-forming dye) and a reflective layer as a recording layer, using a formazan (metal chelate) dye + another dye as a recording material, and using dipyrromethene (metal chelate) dye + another dye as a recording material There are things to use and there is no time to enumerate. Also, there are many known multi-pulse recordings using a dye as a recording material. However, as far as the present inventors know, recording is performed on a dye-based write-once DVD medium with one pulse as in the present invention. Further, there is no literature focusing on a recording waveform when performing high linear velocity recording.

An object of the present invention is to provide an optical recording / reproducing method and apparatus capable of obtaining a good recording waveform when performing high linear velocity recording on a dye-based write-once 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-based medium, and eliminates an unrecorded area in a data rewriting portion as in the LPP system. Provision of an effective method, and an excellent method which does not cause a data error due to a fine cut width control during production of a stamper and leakage of an LPP signal to a data portion, as compared with a DVD-R land pre-pit method. With the goal.

The above object is achieved by the following inventions 1) to 17) (hereinafter, referred to as inventions 1 to 17).
1) For the recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble, the pulse of the shortest mark is a pulse whose output is higher than that of the other marks. Each mark other than the long mark is recorded with one pulse light whose pulse trailing end has a high output for a certain period of time, and when the recording is reproduced with reproduction light, at the time of the mark recording, all marks are recorded. An optical recording / reproducing method for a dye-based write-once DVD medium, wherein an irradiation light amount of a cooling pulse after a rear end portion of the pulse is set to 0.1 mW or less for a predetermined time.
2) The optical recording / reproducing method according to 1), wherein each mark other than the shortest mark is recorded by a single pulse light whose output at two positions, that is, the leading portion and the trailing end thereof, is output for a certain period of time. .
3) The method according to 1) or 2), wherein the time during which the irradiation light amount of the cooling pulse after the rear end of the pulse is set to 0.1 mW or less is set to 1/6 to 6/6 of the shortest space. Optical recording and reproduction method.
4) The head heating pulse width of the recording pulse train forming the mark whose immediately preceding space length is the shortest is distinguished based on whether the length of the mark is the shortest, and the head heating pulse width of the shortest mark is determined. Set the head heating pulse width longer than the head heating pulse width of the non-shortest mark, and determine the head heating pulse width of the recording pulse train forming the shortest mark by determining whether the space length immediately before the shortest mark is the shortest. And 1) to 3) wherein the head heating pulse width of the mark having the shortest space length is set shorter than the head heating pulse width of the mark having the shortest space length. 2. The optical recording / reproducing method according to item 1.
5) The optical recording / reproducing method according to any one of 1) to 4), wherein the wobble frequency is a frequency corresponding to 4T to 96T, where T is a basic clock cycle.
6) The ratio “Wo / PP” between the amplitude (Wo) of the high-frequency wobble 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 ≦ The optical recording / reproducing method according to any one of 1) to 5), wherein synchronization is performed in a range of Wo / PP ≦ 0.4.
7) The optical recording / reproducing method according to any one of 1) to 6), wherein the wavelength of the recording light is 600 to 720 nm.
8) With respect to recording light and reproduction light in a wavelength range of ± 5 nm, the refractive index n of the single recording layer is 1.5 ≦ n ≦ 3.0 and the extinction coefficient k is 0.02 ≦ The optical recording / reproducing method according to any one of 1) to 7), wherein k ≦ 0.2.
9) The optical recording / reproducing method according to any one of 1) to 8), wherein the decomposition start temperature of the recording layer is 100 to 360 ° C.
10) The optical recording 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 hard coat layer on the substrate as a constituent layer other than the recording layer. The optical recording / reproducing method according to any one of 1) to 9).
11) The optical recording / reproducing method according to 10), wherein the reflection layer is made of any one of gold, silver, and aluminum, or an alloy containing these as a main component.
12) The optical recording / reproducing method according to 10) or 11), wherein the protective layer is made of an ultraviolet curable resin.
13) 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 optical recording / reproducing method according to any one of 10) to 12).
14) In a write-once DVD medium having a wobble in the guide groove of the substrate, the pulse of the shortest mark is a pulse whose output is higher than that of the other marks. When recording is performed with one pulse light whose end is output for a certain period of time and the recording is reproduced with reproduction light, the irradiation light quantity of the cooling pulse after the trailing end of the pulse of all marks at the time of the mark recording is described. A recording / reproducing apparatus for a dye-based write-once DVD medium, which has a function of reducing the power to 0.1 mW or less for a predetermined time.
15) The recording according to 14), which has a function of recording each mark other than the shortest mark with one pulsed light having a high output for a certain period of time at two points, that is, the leading and trailing ends of the pulse. Playback device.
16) The function of setting the time for reducing the irradiation light amount of the cooling pulse after the pulse rear end portion to 0.1 mW or less to be 1/6 to 6/6 of the shortest space 14) or 15) The recording / reproducing apparatus according to (1).
17) The head heating pulse width of the recording pulse train forming the mark whose space length immediately before is the shortest is distinguished based on whether or not the length of the mark is the shortest, and the head heating pulse width of the shortest mark is determined. Set the head heating pulse width longer than the head heating pulse width of the non-shortest mark, and determine the head heating pulse width of the recording pulse train forming the shortest mark by determining whether the space length immediately before the shortest mark is the shortest. 14) to 16), wherein the head heating pulse width of the mark having the shortest space length is set shorter than the head heating pulse width of the mark having the shortest space length. The recording / reproducing apparatus according to claim 1.

Hereinafter, the present invention will be described in detail.
The present invention 1 defines a basic optimum pulse irradiation pattern, and the present invention 2 defines a more preferable pulse irradiation pattern.
The present invention 3 defines a preferable condition of the cooling pulse provided at the rear end, and the time for reducing the irradiation light amount of the cooling pulse after the pulse rear end to 0.1 mW or less is 1/6 to 6/6 of the shortest space length. The length is preferably set to 6, and if it is out of this range, it becomes difficult to obtain the effects of the present invention.

Further, for each mark other than the shortest mark, the length at which the power is added to the pulse trailing end portion or the pulse leading and trailing end portions to increase the output power is 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 can be used. Further, the light quantity of the simple pulse of the shortest mark is preferably substantially equal to the added light quantity of each mark other than the shortest mark in terms of waveform control, but may not be equal as long as it can be easily generated on the waveform generation circuit. Good. As the ratio of the added power, W1 / W2 = 1.05 to 3.00 (that is, the added amount is 0.05 to 2.00), where W1 is the total added power and W2 is the non-added power. However, it is preferably in the range of 1.08 to 2.00 (that is, the added amount is 0.08 to 1.00).
By selecting a pulse recording waveform in such a range, good recording can be performed with low jitter, especially in high linear velocity recording.

In a dye-based optical recording medium, the recording power must be increased 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 for improving the cut of the mark edge when forming the mark.
If recording is performed with the conventional example, a difference occurs between the power at which the lowest jitter is obtained and the power at which the error is minimized, and the power margin is reduced. Specifically, in high linear velocity recording, the asymmetry of the recording signal tends to be on the minus side at the recording power at which the lowest jitter can be obtained, and errors tend to occur in error measurement even if the jitter is low. For example, even if the asymmetry is negative and the jitter is low and the error is low, an error is more likely to occur due to aging of the medium and the drive than a medium recorded with the asymmetry near zero. The present invention has been made to solve this low asymmetry problem.

Also, in the case where one mark is written with a plurality of pulsed lights (multi-pulse), the above-described low asymmetry problem can be solved by optimizing the pulsed light. 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 recording speed becomes higher.
On the other hand, in the present invention, since recording is performed with one pulse 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. Further, in address detection during writing, since the recording waveform is simpler than the multi-pulse method, it is easy to average the light amount at the time of recording, and the address is detected by averaging not only the reflected light amount of the space portion but also the light amount of the mark portion. This makes it possible to perform address detection relatively easily even if a cooling pulse of 0.1 mW or less is provided at the end of the pulse.

FIGS. 6 and 8 show an example of a recording waveform corresponding to a case where each mark other than the shortest mark of the present invention 1 is recorded with one pulse light in which the rear end of the heating pulse has a high output for a certain period of time. Shown in In this case, only the shortest length mark is a simple rectangular wave and has a high output, and only the trailing end of the pulse of each of the other marks has a high output at a lower level than the shortest length mark. As for the parameters of the marks other than the shortest mark, only by increasing the output of the rear end of the pulse, almost common parameters can be selected, and there is an advantage that it can be easily developed to practical drives, As a recording medium, good jitter is required with a simplified recording waveform.
On the other hand, a recording waveform corresponding to a case where each mark other than the shortest length mark of the present invention 2 is recorded by one pulse light in which the leading portion and the trailing portion of the heating pulse have a high output for a certain period of time is recorded. FIG. 7 and FIG. In this case, only the shortest mark is a simple rectangular wave and the output is high, and the other two parts of the leading and trailing ends of the pulse of each mark are output at a lower level than the shortest mark. Have been. Therefore, as compared with the cases of FIGS. 6 and 8, it is necessary to increase the output power at the two positions of the leading end and the trailing end except for the shortest mark. Particularly in high-speed recording, when the recording mark length is 4T, The precision of the fall and rise in the middle low power section must be improved. In this regard, a load is imposed on the development of a drive that has been put into practical use, but there is an advantage that a good jitter is easily obtained as a recording medium.

In addition, in consideration of the influence of thermal interference, the head heating pulse width of a recording pulse train that forms a mark whose space length immediately before is the shortest is distinguished by whether the length of the mark is the shortest, The head heating pulse width of the shortest mark is set to be longer than the head heating pulse width of the non-shortest mark (for example, in Table 1 described later, when the immediately preceding space length is 3T and the recording mark length is 3T, 4T to 14T). Reference), recording with lower jitter can be realized.
Further, the head heating pulse width of the recording pulse train forming the shortest mark is distinguished based on whether the space length immediately before the shortest mark is the shortest, and the head heating pulse width of the mark having the shortest space length is shortest. The pulse width is set to be shorter than the head heating pulse width of the mark whose immediately preceding space length is not the shortest (for example, in Table 1 described below, the recording mark length is 3T and the space length is 3T, 4T to 14T). Thus, recording with lower jitter 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, and when the leading pulse width of the pulse train forming the mark is substantially equal to the case of another mark, the space length immediately before is shortened due to thermal interference, Jitter is slightly worse. Therefore, only in such a case, it is effective to shorten the head heating pulse width for recording a mark. Needless to say, it is effective to shorten the leading edge of the first heating pulse when it is desired to further shorten the pulse width.
In addition, when the space length immediately before the mark to be formed is the shortest, if the head heating pulse width of the pulse train forming the mark is shorter than 0.10 T, the mark length itself becomes too short, which is not preferable.
The correction amount (length) when setting the top heating pulse width of the shortest mark longer than that of the other marks is preferably 0.05T to 0.25T. Particularly, as the recording linear velocity increases, it becomes difficult to form the shortest mark. Therefore, the shortest mark is corrected within the above range to increase the leading pulse width of the shortest mark.

Table 1 below shows specific examples of the correction amount of the first heating pulse width.

Next, optical characteristics are required as items required for the recording layer.
As the optical characteristics, the refractive index n of the recording layer single layer with respect to light in the wavelength region near the long wavelength near the recording / reproducing wavelength, that is, light in the wavelength region of ± 5 nm of the recording light and the reproducing light is 1.5 ≦ n ≦ 3.0, and the extinction coefficient k is preferably in the range of 0.02 ≦ k ≦ 0.2. If n is less than 1.5, it is difficult to obtain a sufficient optical change and the recording modulation degree becomes low, which is not preferable. If n exceeds 3.0, the wavelength dependency becomes too high and the recording / reproducing wavelength region becomes too high. However, it is not preferable because an error occurs. If k is less than 0.02, the recording sensitivity deteriorates, which is not preferable. If k exceeds 0.2, it is difficult to obtain a reflectance of 50% or more, which is not preferable.
The DVD is standardized around 650 nm in a read-only device, but the recording light wavelength of a recordable medium is standardized at 650 to 660 nm for general use in addition to 635 nm of an authoring-only medium. However, these wavelengths are only central wavelengths, and vary to a short wavelength side and a long wavelength side due to variations in LD manufacturing. Also, due to its characteristics, the LD generally shifts its wavelength to longer wavelengths when the temperature rises. The present invention is a method that can be performed 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 cycle, which is about 0.133 μm for DVD (4.7 GB) media. About 38 nsec. It is.
Normally, a frequency band corresponding to 150T to 400T is used as a wobble frequency band. In this frequency band, the frequency of the wobble is too low when data is added regardless of frequency modulation or phase modulation. The gap between the added data and the data is considerably vacant, which is not suitable for high-density recording. On the other hand, in the DVD-R, an LPP is provided, and the position where data is written is controlled by the LPP signal.
However, in the LPP system, if the signal amplitude of the LPP is too small, the LPP cannot be read well. Conversely, if the LPP is too large, the LPP signal leaks into the write data and a data error frequently occurs. , LPP have 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 the stamper is manufactured.
On the other hand, if high-frequency wobbles are used, the LPP is not required, and the wobbles are modulated and synchronized, so that a situation in which data errors frequently occur unlike the LPP method does not occur. As specified in the present invention 5, the preferred frequency of the high frequency wobble is 4T to 96T. If it is less than 4T, it is difficult to detect the frequency because it is too high, and there is a problem in the rotation control and the address detection reliability. On the other hand, if it is larger than 96T, the frequency is too low, and the gap at the seam at the time of additionally writing data is too large, causing problems such as a reduction in capacity and a reduction in data processing speed.

The amplitude of the wobble of the DVD medium to which the present invention is applied is determined by the wobble amplitude (Wo) of the signal passed through a suitable filter, for example, a high and low pass filter of 4 MHz and 30 kHz, and the wobble amplitude (Wo) of an appropriate filter, for example, a filter of 30 kHz. If the ratio Wo / PP of the push-pull signal (PP) satisfies 0.1 ≦ Wo / PP ≦ 0.4, the synchronization of the wobble as 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 for synchronization, and if it exceeds 0.4, the data part error tends to increase. However, as compared with the LPP method, the influence of a medium having a large LPP on the occurrence of a data error is small, and the data error associated with an increase in the wobble amplitude is moderate.
Further, when producing a stamper, an advanced cut width control technique is required to keep the LPP cut width of the LPP method within the above-mentioned range of 0.16 to 0.32, but in the high frequency wobble method of the present invention, The objective is achieved only by controlling the high-frequency generation source and the magnitude of the wobble swing amount (the swing amount can be arbitrarily reproduced with a circuit that controls the wobble swing amount). Can be dramatically improved.

Further, as for the groove shape of the substrate having the above-mentioned format, for example, when a recording layer is formed by a solvent coating method using an organic dye, a preferable groove depth is 1000 to 2500 °, more preferably 1500 °. Å2000Å. If the groove depth is less than 1000 °, the push-pull signal cannot be sufficiently obtained and tracking control cannot be performed. On the other hand, if the angle exceeds 2500 °, the transferability during the molding of the substrate becomes low, which is not preferable.
Further, when the dye recording layer is provided, the depth of the dye groove is preferably in the range of 1200 ≦ d1 × m ≦ 1600000 when the wobble frequency is mT (m is a natural number) and the depth of the dye groove 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 / reproducing. If d1 × m exceeds 160,000, it oscillates in reverse. There is also a limit of the substrate groove depth due to the transfer limit of the substrate molding described above, and therefore, it cannot substantially exceed 160000.
In addition, the track pitch needs to be about 0.64 to 0.8 μm in order to secure a recording density of 4 to 5 GB. Although the groove width varies depending on the recording material, it can be applied to almost all organic materials with a half width of 0.18 to 0.40 μm.

Next, the layer structure of the dye-based write-once DVD medium, the necessary characteristics of each layer, and the constituent materials of the present invention will be described.
1A to 1D show an example of a layer configuration of a normal write-once optical disc, and FIGS. 2A to 2C show an example of a layer configuration of a normal CD-R medium. 3) to 3 (c) are examples of the layer structure of the write-once DVD medium, and a preferable basic structure of the dye-based write-once DVD medium to which the present invention is applied is as shown in FIGS. 3 (b) and 3 (c). The first substrate and the second substrate (protective substrate) are bonded with an adhesive with a recording layer therebetween.
The recording layer may be a single layer of an organic dye layer or a laminate of an organic dye layer and a reflective layer to increase the reflectance. 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 most commonly used structure is composed of a first substrate / organic dye layer / reflection layer / protective layer / adhesive layer / second substrate (protective substrate).

"substrate"
The substrate must be transparent to the laser used when performing recording and reproduction from the substrate side, but need not be transparent when performing recording and reproduction from the recording layer side. As the substrate material, for example, a plastic such as a polyester resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a polyolefin resin, a phenol resin, an epoxy resin, and a polyimide resin, or glass, ceramic, or metal can be used. Note that a guide groove or guide pit for tracking and a preformat such as an address signal may be formed on the surface of the substrate.

《Recording layer》
The recording layer causes some optical change by laser beam irradiation and records information by the change, and a dye is preferable as the material.
Examples of dyes include azo, formazan, dipyrromethene, (poly) methine, naphthalocyanine, phthalocyanine, tetraazaporphyrin, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indance) Len), xanthene, triphenylmethane, azulene, tetrahydrocholine, phenanthrene, triphenothiazine dyes, and metal complexes thereof. Of these, azo (metal chelate) dye, formazan (metal chelate) dye, squarylium (metal chelate) dye, dipyrromethene (metal chelate) dye, trimethine cyanine dye, and tetraazaporphyrin dye are preferred.
The pigment preferably has a decomposition start temperature of 100 to 360 ° C, more preferably 100 to 350 ° C, as its thermal decomposition property. If the decomposition start temperature exceeds 360 ° C., pit formation at the time of recording is not performed well, and the jitter characteristics deteriorate. On the other hand, when the temperature is lower than 100 ° C., the storage stability of the disc deteriorates.

The above dye may be mixed with other organic dyes, metals, and metal compounds for the purpose of improving optical properties, recording sensitivity, signal characteristics, and the like, or a dye layer and a layer made of another organic dye, a metal, and a metal compound. 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. They can be used by lamination.
Further, various materials such as a polymer material, for example, an ionomer resin, a polyamide resin, a vinyl resin, a natural polymer, silicone, and a liquid rubber, or a silane coupling agent may be dispersed and mixed in the dye, For the purpose of improving properties, a stabilizer (eg, a transition metal complex), a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like can be used together.

The formation of the recording layer can be performed by ordinary means such as vapor deposition, sputtering, CVD, and solvent application. When the coating method is used, the above-mentioned dye or the like is dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, and spin coating. As the organic solvent to be used, generally, 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, pentane , Cyclohexane, and hydrocarbons such as methylcyclohexane.
The film thickness of the recording layer is suitably 100 to 10 μm, preferably 200 to 2000 °.

《Undercoat layer》
The undercoat layer includes (1) an improvement in adhesiveness, (2) a barrier against water or gas, (3) an improvement in storage stability of the recording layer, (4) an improvement in reflectance, and (5) a substrate from a solvent. And (6) forming guide grooves, guide pits, and preformats. For the purpose of (1), various polymer compounds such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, or silane coupling agents can be used. For the purposes of (2) and (3), inorganic compounds such as SiO, MgF, SiO ₂ , TiO, ZnO, TiN, and SiN can be used in addition to the above polymer materials. , Ni, Cr, Ge, Se, Au, Ag, Al, and other metals or metalloids. For the purpose of (4), an organic thin film having a metallic luster, such as a metal such as Al, Au, and Ag, or a methine dye or a xanthene dye 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 suitably from 0.01 to 30 μm, preferably from 0.05 to 10 μm.

《Reflective layer》
Examples of the material of the reflection layer include metals and semimetals such as Au, Ag, Cr, Ni, Al, Fe, and Sn which are not easily corroded and provide high reflectance by themselves, but from the viewpoint of reflectance and productivity. Au, Ag, and Al are particularly preferred. Further, these metals and semimetals 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 °, preferably 100 to 3000 °.

《Protective layer, hard coat layer on substrate surface》
The protective layer and the hard coat layer on the substrate surface include (1) protection of the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc., (2) improvement of 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. In addition, 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. An organic material such as a softening or hot-melting resin can also be used. Most preferred is an ultraviolet curable resin having excellent productivity.
The thickness of the protective layer or the hard coat layer on the substrate surface is 0.01 to 30 μm, preferably 0.05 to 10 μm.
The undercoat layer, the protective layer and the 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 as in the case of the recording layer. it can.

《Protective substrate》
The protective substrate must be transparent to the used laser light when irradiating laser light from the protective substrate side, but need not be transparent when used as a simple protective plate.
The usable protective substrate material is exactly the same as the above-mentioned substrate material, such as polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide resin, etc., or glass, ceramic, metal, etc. Can be used.
《Adhesive layer》
Any material can be used for the adhesive layer as long as it can bond two recording media, and in consideration of productivity, an ultraviolet curable adhesive or a hot melt adhesive is preferable.

  The DVD-RAM / WO, DVD-R, DVD + R, and DVD-RAM, DVD-RW, and DVD + RW 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 multiple times. Information is recorded and reproduced on and from these optical disks such as DVD + R and DVD + RW disks by a drive as shown in FIG.

  FIG. 10 is a functional block diagram showing an example of a main 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 servo means, 17 is a DVD decoder, 18 is an ADIP decoder, 19 is a laser controller, and 20 is a DVD. Encoder, 21 is a DVD-ROM encoder, 22 is a buffer RAM, 23 is a buffer manager, 24 is a DVD-ROM decoder, 25 is an ATAPI / SCSI interface, 26 is a D / A converter, 27 is ROM, 28 is CPU, 29 is A RAM is shown, LB is a laser beam, and Audio is an audio output signal.

In FIG. 10, arrows indicate the directions in which data mainly flows. For simplification of the drawing, the CPU 28 that controls each block in FIG. Is omitted. The ROM 27 stores a control program described in a code that can be decoded by the CPU 28. When the power of 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 and the like necessary for the control. In the RAM 29.
The configuration and operation of the optical disk drive are as follows. The optical disk 11 is driven to rotate by a spindle motor 12. The spindle motor 12 is controlled by a motor driver 14 and servo means 16 so that the linear velocity or the angular velocity becomes constant. This linear velocity or angular velocity can be changed stepwise.

The optical pickup 13 incorporates 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 laser light LB. The optical pickup 13 can be moved in the sledge direction by a seek motor. In these focus actuator, track actuator, and seek motor, the spot of the laser beam LB is located at a target location on the optical disc 11 by the motor driver 14 and the servo unit 16 based on signals obtained from the light receiving element and the position sensor. Is controlled as follows.
Then, at the time of reading, the reproduction signal obtained by the optical pickup 13 is amplified by the read amplifier 15 and binarized, and then input to the DVD decoder 17. The input binary data is subjected to 8/16 demodulation in the DVD decoder 17. It should be noted that the recording data is modulated in a group of 8 bits (8/16 modulation), and in this modulation, 8 bits are converted to 16 bits. In this case, the combined bits are attached so that the number of “1” and “0” up to that time 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, the data is input to the DVD-ROM decoder 24, and further error correction processing is performed to improve the reliability of the data. The data on which the error correction processing has been performed twice is temporarily stored in the buffer RAM 22 by the buffer manager 23, and is sent to the host computer (not shown) via the ATAPI / SCSI interface 25 in a state of being prepared as sector data. 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, the laser spot needs to be positioned at the write start point before that. In the case of DVD + RW / + R, this point is determined by a wobble signal which is previously carved on the optical disk 11 by meandering of the track.

Note that the above-mentioned point is 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 on the DVD + RW / + R disc includes address information called ADIP (ADless In Pre-groove), and this information is taken out by the ADIP decoder 18. The synchronizing signal generated by the ADIP decoder 18 is input to the DVD encoder 20 to enable data to be written at an accurate position on the optical disk 11. The data in the buffer RAM 22 is subjected to addition of an error correction code and interleaving in the DVD-ROM encoder 21 and the DVD encoder 20, and the recording power and the recording waveform of the present invention via the laser controller 19 and the optical pickup 13. 11 is recorded.

The recording / reproducing apparatus according to the fourteenth aspect of the present invention is directed to a dye-based write-once DVD medium having a wobble in a guide groove of a substrate, wherein the pulse of the shortest mark is a pulse whose output is higher than that of the other marks. Other marks are recorded with one pulse light whose pulse trailing end has a high output for a certain period of time, and when the recording is reproduced with reproduction light, at the time of the mark recording, after the mark pulse Since it has a function of reducing the irradiation light amount of the cooling pulse after the end to 0.1 mW or less for a certain period of time, high quality recording at a high linear velocity can be realized.
Also, the recording / reproducing apparatus of the fifteenth aspect of the present invention has a function of recording each mark other than the shortest mark with one pulse light whose output is made high for a certain period of time at two points, the leading and trailing ends of the pulse. The recording quality at high linear velocity can be improved.

In addition, the recording / reproducing apparatus of the sixteenth aspect of the present invention has a function of setting the time for irradiating the cooling pulse after the trailing end of the pulse to be 1/6 to 6/6 of the shortest space. By adopting the range, the recording quality can be further improved.
Further, the recording / reproducing apparatus of the seventeenth aspect of the present invention distinguishes the first heating pulse width of a recording pulse train forming a mark whose immediately preceding space length is the shortest by whether the length of the mark is the shortest, The head heating pulse width of the shortest mark is set to be longer than the head heating pulse width of the non-shortest mark, and the head heating pulse width of the recording pulse train forming the shortest mark is set to the space length immediately before the shortest mark. Has the function of setting the head heating pulse width of the mark whose immediately preceding space length is the shortest shorter than the head heating pulse width of the mark whose immediately preceding space length is not the shortest. Thus, high-quality recording, that is, low jitter can be realized.
The method for obtaining address information may be a method for obtaining address information from land pre-pits or pre-pits.

FIG. 11 is a schematic diagram of an information processing apparatus using the optical disk drive shown in FIG.
The information processing device 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 is shown), and controls the entire host computer.
The interface is a two-way communication interface with the optical disk drive, and conforms to standard interfaces such as ATAPI and SCSI. The interface is connected to the interface 25 of the optical disk drive described above. The connection 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 or the like.

The recording device (HDD, hard disk) stores a program described in a code readable by a microcomputer of the main control device. When the drive power supply of the information processing device is turned on, the program is loaded into the main memory of the main control device.
The display device includes a display unit (not shown) such as a CRT, a liquid crystal display (LCD), and a plasma display panel (PDP), and displays various information from the control device.
The input device includes, for example, at least one input medium (not shown) among a keyboard, a mouse, a pointing device, and the like, and notifies the main control device of various information input by the user. The information from the input medium may be input by a wireless method. In addition, as an integrated display device and input device, for example, there is a CRT with a touch panel. The information processing apparatus has 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, low jitter and low error rate recording can be performed at any linear velocity on a dye-based write-once DVD medium, and it can be manufactured more easily than the land prepit format used in DVD-R. The addition of the data part can be efficiently performed in a high frequency wobble format. In addition, it is possible to record on a dye-based write-once DVD medium having almost the same format as CD-Rs and CD-RWs that are currently mass-produced.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1 to 9, Comparative Examples 1 to 6
On an injection molded polycarbonate substrate having a groove depth of 1750 °, a half width of 0.33 μm, a track pitch of 0.74 μm, a guide groove equivalent to a wobble frequency of 32T, a thickness of 0.6 mm, and an outer diameter of 120 mm, the following [Chemical Formula 1] and [ The compound of formula 2) is weighed at a weight ratio of 60:40, dissolved in 2,2,3,3-tetrafluoro-1-propanol and spin-coated to form an organic dye layer having a thickness of 1200 ° Dry at 30 ° C. for 30 minutes.
Next, a reflection layer of silver 1100 ° is provided by a sputtering method, and a protective layer of 5 μm in thickness is further provided with an acrylic photopolymer thereon. Then, an injection-molded polycarbonate flat substrate having a thickness of 0.6 mm and an outer diameter of 120 mm is prepared. An optical recording medium was obtained by bonding with an acrylic photopolymer.

<Recording and playback conditions>
EFM signals (minimum pit length: about 0.4 μm) were recorded on the above optical recording medium while tracking using a semiconductor laser beam having an oscillation wavelength of 660 nm and a beam diameter of 0.9 μm. Then, recording was performed with a recording power such that Bottom Jitter (bottom jitter) was minimized, and that portion was reproduced to determine a jitter value, asymmetry, and the number of PI errors. The waveform of the recording laser light is as shown in FIGS. W1 is the added power as a whole, and W2 is the added power. Furthermore, the pulse lengths of FIGS. 4 to 9 are used for the pulse lengths of the linear velocities of 21 m / s and 28 m / s, but the present invention is not limited to this.
In Example 8, the cooling amount was set to 0.4T, which was 1/6 of the shortest space length 3T of the present invention, that is, shorter than 0.5T. In Comparative Example 1, the light intensity of the cooling portion was 0.7 mW, which was the same as the reproduction light power. That is, a recording waveform having no cooling pulse was used. In Comparative Example 2, the light amount of the cooling portion was 0.4 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 cooling.

なお、表中のＷＯは最短マークパルスパワーである。
上記表２から分るように、実施例１〜８は、比較例１〜３に比べてジッタ、アシンメトリ共に良好である。

WO in the table is the shortest mark pulse power.
As can be seen from Table 2, Examples 1 to 8 have better jitter and asymmetry than Comparative Examples 1 to 3.

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４のようにＬＰＰｂが０．１６を下回るレベルであると実際に用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, an EFM signal (minimum pit length of about 0.4 μm) was recorded on the optical recording medium while tracking using a semiconductor laser beam having an oscillation wavelength of 660 nm and a beam diameter of 0.9 μm. Recording was performed at a linear velocity and with a recording power such that the bottom jitter was minimized under the conditions with the correction shown in Table 1, and that portion was reproduced to determine the jitter value, asymmetry, and the number of PI errors.
In Comparative Examples 4 to 6, the size of the LPPb of the LPP format used in the DVD-R was changed (changed), and the size of the LPPb was changed (changed). A recording medium was prepared and evaluated in the same manner as in the examples.

As can be seen from Table 3, in the LPP format sample, when LPPb increases, the PI error increases even if the jitter is good. In addition, it was confirmed that when LPPb was lower than 0.16 as in Comparative Example 4, it was impossible to detect an address in a device actually used.

(A)-(d) The figure which shows the example of a layer structure of a usual write-once 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 example of a layer structure of a dye-based write-once DVD medium. FIG. 8 is a diagram showing a conventional example of a superimposed type emission waveform on the rear end of a mark other than the shortest mark for a recording linear velocity of 28 m / s. FIG. 9 is a diagram showing a conventional example of a superimposed type emission waveform on a head portion and a rear end portion of a mark other than the shortest mark for a recording linear velocity of 28 m / s. The figure which shows the example of this invention of the light emission waveform added to the rear end part of marks other than the shortest mark for recording linear velocity of 28 m / s. FIG. 4 is a diagram showing an example of the present invention of a light emission waveform superimposed on a head portion and a rear end portion of marks other than the shortest mark for a recording linear velocity of 28 m / s. The figure which shows the example of this invention of the light emission waveform added to the rear end part of the mark other than the shortest mark for a recording linear velocity of 21 m / s. The figure which shows the example of this invention of the light emission waveform added to the head part and the rear end part of marks other than the shortest mark for recording linear velocity of 21 m / s. FIG. 2 is a functional block diagram illustrating an example of a main configuration of the optical disc drive. FIG. 11 is a schematic diagram of an information processing apparatus using the optical disk drive shown in FIG.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Undercoat layer 4 Protective layer 5 Substrate surface hard coat layer 6 Reflective layer 7 Protective substrate 8 Adhesive layer space Space mark Mark Cooling Area Cooling area T Basic clock cycle n Integer of 3 or more n 'Integer of 3 or more ps Space length immediately before cm Recording mark length W1 Overall added power W2 No additional power

Claims (17)

  For the recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with wobbles, the pulse of the shortest mark is a pulse whose output is higher than that of the other marks, and the shortest mark is Other marks are recorded with one pulse light whose pulse trailing end has a high output for a certain period of time, and when the recording is reproduced with reproduction light, at the time of the mark recording, after the mark pulse An optical recording / reproducing method for a dye-based write-once DVD medium, wherein an irradiation light amount of a cooling pulse after an end portion is set to 0.1 mW or less for a predetermined time.   2. The optical recording / reproducing method according to claim 1, wherein each mark other than the shortest mark is recorded with one pulse light whose output power is increased for a certain period at two points, a leading portion and a trailing end portion.   3. The optical recording according to claim 1, wherein the time for reducing the irradiation light amount of the cooling pulse after the pulse rear end portion to 0.1 mW or less is set to 1/6 to 6/6 of the shortest space. Playback method.   The head heating pulse width of the recording pulse train that forms the mark whose immediately preceding space length is the shortest is distinguished based on whether the length of the mark is the shortest, and the head heating pulse width of the shortest mark is the shortest. Is set longer than the head heating pulse width of the mark that is not, and distinguishes the head heating pulse width of the recording pulse train that forms the shortest mark by whether the space length immediately before the shortest mark is the shortest. The head heating pulse width of a mark whose space length immediately before is shortest is set shorter than the head heating pulse width of a mark whose space length immediately before is not shortest. Optical recording and reproduction method.   5. The optical 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 cycle.   The ratio “Wo / PP” between the amplitude (Wo) of the high-frequency wobble 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 / 6. The optical recording / reproducing method according to claim 1, wherein the synchronization is performed within a range of PP ≦ 0.4.   7. The optical recording / reproducing method according to claim 1, wherein the wavelength of the recording light is 600 to 720 nm.   For light in the wavelength range of recording light and reproduction light of ± 5 nm, the refractive index n of the single recording layer is 1.5 ≦ n ≦ 3.0, and the extinction coefficient k is 0.02 ≦ k ≦ 8. The optical recording / reproducing method according to claim 1, wherein the value is 0.2.   The optical recording / reproducing method according to any one of claims 1 to 8, wherein a decomposition start temperature of the recording layer is 100 to 360 ° C.   The optical recording medium has, on the substrate, as a constituent layer other than the recording layer, 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. 10. The optical recording / reproducing method according to any one of 1 to 9.   The optical recording / reproducing method according to claim 10, wherein the reflection layer is made of any one of gold, silver, and aluminum, or an alloy containing these as a main component.   The optical recording / reproducing method according to claim 10, 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 an adhesive used for the adhesive layer is an ultraviolet curable resin. 13. The optical recording / reproducing method according to any one of 10 to 12.   For a write-once DVD medium having a wobble in the guide groove of the substrate, the pulse of the shortest mark is a pulse whose output is higher than that of the other marks. Is recorded with one pulse light of high output for a certain period of time, and when the recording is reproduced with reproduction light, at the time of the mark recording, the irradiation light amount of the cooling pulse after the pulse trailing end of all the marks is A recording / reproducing apparatus for a dye-based write-once DVD medium, having a function of reducing the power to 0.1 mW or less for a predetermined time.   15. The recording / reproducing apparatus according to claim 14, wherein each mark other than the shortest mark has a function of recording with one pulse light whose output power is increased for a certain period of time at two points, a leading part and a trailing end. apparatus.   16. The function having a function of setting the time for reducing the irradiation light amount of the cooling pulse after the pulse rear end portion to 0.1 mW or less to be 1/6 to 6/6 of the shortest space. Recording and playback device. The head heating pulse width of the recording pulse train that forms the mark whose immediately preceding space length is the shortest is distinguished by whether the length of the mark is the shortest, and the head heating pulse width of the shortest mark is the shortest. Is set longer than the head heating pulse width of the mark that is not, and distinguishes the head heating pulse width of the recording pulse train that forms the shortest mark by whether the space length immediately before the shortest mark is the shortest. 17. The head heating pulse width of a mark whose space length immediately before is shortest is set shorter than the head heating pulse width of a mark whose space length immediately before is not shortest. Recording and playback device.

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