JP2004303400A - 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 or the marks other than the shortest mark and a next shortest mark are recorded by one pulse light beam, in which high output power is applied to a leading section and a back end section of a heating pulse during 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 recordable DVD medium.

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

  Known examples of optical recording media using a dye in the recording layer include polymethine dyes or those using a polymethine dye and a light stabilizer as a recording material, tetraazaporphyrin (porphyrazine) dye or cyanine dye + azo metal chelate. A recording layer composed of a dye (salt-forming dye) and a reflective layer, a formazan (metal chelate) dye + other dye as a recording material, a dipyrromethene (metal chelate) dye + other dye as a recording material There are things to use and there is no time for enumeration. In addition, many recording materials are known that perform multi-pulse recording using a dye. To the best knowledge of the present inventors, recording is performed with one pulse on a dye-based recordable DVD medium as in the present invention. In addition, there is no literature that focuses on the recording waveform when performing high linear velocity recording.

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 recordable DVD medium.
Further, the present invention is a new format method of a write-once DVD system using a semiconductor laser having an oscillation wavelength shorter than that of a CD medium, and, like the LPP method, eliminates an unrecorded area in a data added portion. 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 19) (hereinafter referred to as the present inventions 1 to 19).
1) For a recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble, each mark other than the shortest length mark or each mark other than the shortest length mark and the next shortest mark When recording with one pulse light whose output is increased for a certain period of time at the beginning and the rear end of the heating pulse and reproducing the recording with the reproduction light, all marks are recorded at the time of the mark recording. An optical recording / reproducing method for a dye-based write-once DVD medium, characterized in that an irradiation light amount of a cooling pulse after the rear end 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 the shortest length mark or the shortest length mark and the next shortest mark are always recorded with one pulsed light having a constant power.
3) The optical recording / reproducing method according to 2), wherein the pulsed light power having a constant power is made equal to the pulsed light power at two high outputs at the head part and the rear part of the pulse.
4) Any one of 1) to 3), wherein the cooling pulse irradiation light amount after the rear end of the pulse is set to a length of 1/6 to 6/6 of the shortest long space. 2. An optical recording / reproducing method according to 1.
5) The head heating pulse width of the recording pulse train 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 head heating pulse width of the shortest mark is determined. The head heating pulse width of the recording pulse train that forms the shortest length mark is set longer than the head heating pulse width of the mark that is not the shortest length, and whether or not the space length immediately before the shortest length mark is the shortest length. Any one of 1) to 4), characterized in that the head heating pulse width of the mark having the shortest previous space length is set shorter than the head heating pulse width of the mark having the shortest previous space length. 2. An optical recording / reproducing method according to 1.
6) The optical recording / reproducing method according to any one of 1) to 5), wherein the frequency of the wobble is a frequency corresponding to 4T to 96T, where T is a basic clock period.
7) 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 6), wherein synchronization is performed within a range of Wo / PP ≦ 0.4.
8) The optical recording / reproducing method according to any one of 1) to 7), wherein the wavelength of the recording light is 600 to 720 nm.
9) The refractive index n of the recording layer single layer is 1.5 ≦ n ≦ 3.0 and the extinction coefficient k is 0.02 ≦ with respect to the light in the wavelength range of the recording light and the reproducing light wavelength ± 5 nm. The optical recording / reproducing method according to any one of 1) to 8), wherein k ≦ 0.2.
10) The optical recording / reproducing method according to any one of 1) to 9), wherein the decomposition start temperature of the recording layer is 100 to 360 ° C.
11) The optical recording medium has at least one layer selected from a reflective layer, a protective layer, an adhesive layer, a protective substrate, and a substrate surface hard coat layer as a constituent layer other than the recording layer on the substrate. The optical recording / reproducing method according to any one of 1) to 10).
12) The optical recording / reproducing method according to 11), wherein the reflective layer is made of gold, silver, or aluminum, or an alloy containing them as a main component.
13) The optical recording / reproducing method according to 11) or 12), wherein the protective layer comprises an ultraviolet curable resin.
14) An adhesive layer for bonding two substrates to form a recording medium having a double-sided structure is provided between the substrates, and the adhesive used for the adhesive layer is an ultraviolet curable resin. The optical recording / reproducing method according to any one of 11) to 13).
15) For write-once DVD media having wobbles in the guide groove of the substrate, marks other than the shortest length mark, or marks other than the shortest length mark and the next shortest mark, are placed at the head and rear end of the heating pulse. When recording is performed with one pulsed light whose output has been increased for a certain period of time at two locations and the recorded data is reproduced with the reproduced light, the irradiation light quantity of the cooling pulse after the trailing edge of all the marks during the mark recording The recording / reproducing apparatus for a dye-based write-once DVD medium characterized by having a function of keeping the recording time at 0.1 mW or less for a certain time.
16) The recording / reproducing apparatus according to 15), which has a function of always recording the shortest length mark or the shortest length mark and the next shortest mark with one pulsed light having a constant power.
17) The recording / reproducing apparatus according to 15) or 16), wherein the recording / reproducing apparatus has a function of equalizing the pulsed light power of constant power and the high-powered pulsed light power at two positions at the head and rear ends of the pulse. .
18) The cooling pulse irradiation light quantity after the rear end of the pulse has a function of setting the time to be 0.1 mW or less to 1/6 to 6/6 of the shortest long space 15) to 17) A recording / reproducing apparatus according to any one of the above.
19) The head heating pulse width of the recording pulse train 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 head heating pulse width of the shortest mark is determined. The head heating pulse width of the recording pulse train that forms the shortest length mark is set longer than the head heating pulse width of the mark that is not the shortest length, and whether or not the space length immediately before the shortest length mark is the shortest length. 15) to 18) characterized by having a function of setting the head heating pulse width of the mark having the shortest preceding space length shorter than the head heating pulse width of the mark having the shortest preceding space length. A recording / reproducing apparatus according to any one of the above.

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 the power of the shortest mark or the shortest mark and the next shortest mark.
According to the third aspect of the present invention, an optimum power distribution is defined so that an extra load is not applied to the recording / reproducing apparatus by the recording power (pulsed light power) which is increased by adding the extra power when forming each mark. It is a thing.
The present invention 4 defines preferable conditions for the cooling pulse provided at the rear end, and the time for reducing the irradiation light amount of the cooling pulse after the rear end of the pulse to 0.1 mW or less is 1/6 to 6 / of the shortest space length. The length of 6 is preferable, and if it is out of this range, it is difficult to obtain the effect of the present invention.

For each mark other than the shortest mark, or for each mark other than the shortest mark and the next shortest mark, the length to increase the power by adding power to the head and rear ends of the pulse is the basic clock cycle. A range of 0.5 to 2 times 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. The light quantity of the simple pulse of the shortest length mark or the shortest length mark and the next shortest mark is substantially the same as the amount of light added to each mark other than the shortest length mark or each mark other than the shortest length mark and the next shortest mark. Although they are preferably equal, they need not be equal as long as they can be easily generated on the waveform generation circuit. The ratio of the additional power can be adopted in the range of W1 / W2 = 1.05 to 3.00 (ie, the additional amount is 0.05 to 2.00), where W1 is the total additional power and W2 is the non-addition 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, it is possible to perform good recording with low jitter, particularly in high linear velocity recording.

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.

FIG. 6 shows a recording waveform corresponding to the case where each mark other than the shortest length mark of the present invention 1 is recorded with one pulse light in which the head pulse and the trailing edge of the heating pulse are output for a certain period of time. This is shown in FIG. In this case, only the shortest mark is a simple rectangular wave, and almost all common parameters can be selected for the parameters other than the shortest mark. However, depending on the recording medium, a simplified recording waveform with good jitter is required, and in high-speed recording, when the recording mark length is 4T, the falling and rising accuracy in the middle low power part Must be increased. Only in the 4T portion, the load to the drive is applied.
On the other hand, when recording each mark other than the shortest length mark and the next shortest mark according to the present invention 1 with a single pulsed light whose output is increased for a certain period of time at the front and rear end portions of the heating pulse. The corresponding recording waveforms are shown in FIGS. In this case, the shortest mark and the next shortest mark are simple rectangular waves, and almost the same parameters can be selected for the parameters of the other marks, but it is practical compared to the cases of FIGS. There is a load to deploy to the drive that has become.

In consideration of the influence of thermal interference, the head heating pulse width of the recording pulse train forming the mark having the shortest space length immediately before is distinguished by whether or not the mark length is the shortest length, The head heating pulse width of the shortest mark is set to be longer than the head heating pulse width of the mark which is not the shortest length (as an example, in 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 head heating pulse width of the recording pulse train 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 head heating of the mark having the shortest space length immediately before is determined. The pulse width is set to be shorter than the head heating pulse width of the mark whose space length is not the shortest immediately before (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). 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 length, and the head pulse width of the pulse train forming the mark is substantially equal to the case of 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 head heating pulse width for recording the mark. Needless to say, if it is desired to further reduce the pulse width, it is effective to shorten the leading edge of the leading heating pulse.
In addition, when the space length immediately before the mark to be formed is the shortest length, it is not preferable that the head heating pulse width of the pulse train forming the mark is shorter than 0.10 T because the mark length itself becomes too short.
The correction amount (length) when the head 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 is increased, it becomes difficult to form the shortest length mark. Therefore, the leading pulse width of the shortest length mark is increased by correcting within the above range.

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

Next, optical characteristics are listed as items necessary for the recording layer.
As an optical characteristic, the refractive index n of the recording layer single layer with respect to light in the wavelength range near the long wavelength near the recording / reproducing wavelength, that is, light in the wavelength range of ± 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. 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 the sixth aspect of the present invention, the preferred frequency of the high frequency wobble is 4T to 96T. If the frequency is smaller than 4T, the frequency becomes too high to be detected, and there is a problem in terms of rotation control and address detection reliability. On the other hand, when the frequency is larger than 96T, the frequency is too low, and the gap is too wide at the seam when data is additionally written, causing problems such as a decrease in capacity and a decrease in data processing speed.

The wobble amplitude of the DVD medium to which the present invention is applied is 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.
The recording layer may be a single organic dye layer or a laminate of an organic dye layer and a reflective layer to increase reflectivity. An undercoat layer or a protective layer may be provided between the recording layer and the substrate, and each layer may have a laminated structure of two or more layers for improving the function. The structure most commonly used is a structure comprising a first substrate / organic dye layer / reflective layer / protective layer / adhesive layer / second substrate (protective substrate).

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

<Recording layer>
The recording layer causes some optical change upon irradiation with laser light and records information by the change, and the material is preferably a dye.
Examples of dyes include azo, formazan, dipyrromethene, (poly) methine, naphthalocyanine, phthalocyanine, tetraazaporphyrin, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indance) Ren), 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 metal, metal compound, In, Te, Bi, Se , Sb, Ge, Sn, Al, Be, TeO 2, SnO, As, Cd , and the like, or whether the respectively dispersed and mixed 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.

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

In FIG. 10, the arrow indicates 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, an optical system, a focus actuator, a track actuator, a light receiving element, and a position sensor (not shown), and irradiates the optical disk 11 with a laser beam LB. The optical pickup 13 can be moved in the sledge direction by a seek motor. These focus actuator, track actuator, and seek motor are positioned at a target location on the optical disk 11 by the motor driver 14 and the servo means 16 based on signals obtained from the light receiving element and the position sensor. To be controlled.
At the time of reading, the reproduction signal obtained by the optical pickup 13 is amplified and binarized by the read amplifier 15 and then input to the DVD decoder 17. The input binarized data is demodulated 8/16 in the DVD decoder 17. Note that the recording data is modulated in units of 8 bits and modulated (8/16 modulation). In this modulation, 8 bits are converted to 16 bits. In this case, the combined bits are attached so that the number of previous “1” s and “0” s are equal on average. This is called “DC component suppression”, and the slice level fluctuation of the DC-cut reproduction signal is suppressed.

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

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

The recording / reproducing apparatus of the present invention 15 heats each mark other than the shortest length mark or each mark other than the shortest length mark and the next shortest mark on a dye-based recordable DVD medium having wobbles in the guide groove of the substrate. When recording with one pulse light whose output has been increased for a certain period of time at the beginning and rear end of the pulse, and reproducing the recording with the reproduction light, after recording all marks, Since it has a function of setting the irradiation light quantity of the cooling pulse after the end to 0.1 mW or less for a certain time, it is possible to realize high quality recording at a high linear velocity.
Further, the recording / reproducing apparatus of the present invention 16 has a function of making the pulse power of the shortest length mark with a short pulse length or the shortest length mark and the next shortest mark constant, so that the apparatus can be simplified. In other words, if the power is raised or lowered within a short time, a control technique such as a high-performance LD driver is required and the apparatus becomes complicated, but this is not the case with the present invention 16.
In addition, as in the recording / reproducing apparatus of the present invention 17, the power of the pulse light of constant power (pulse light for the shortest length mark or the next shortest mark) and the high output of the pulse head portion and the rear end portion are increased. Also, having the function of equalizing the pulsed light power can reduce the load on the drive system, and has an advantage that the device can be easily manufactured.

Further, the recording / reproducing apparatus of the present invention 18 has a function of setting the time for irradiating the cooling pulse after the rear end of the pulse to a length of 1/6 to 6/6 of the re-short space, so that a more preferable cooling pulse. By adopting the range, it is possible to further improve the recording quality.
Furthermore, the recording / reproducing apparatus of the present invention 19 distinguishes the head heating pulse width of the recording pulse train forming the mark having the shortest space length immediately before by whether the mark length is the shortest length, 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 to set the head heating pulse width of the mark with the shortest previous space length shorter than the head heating pulse width of the mark with the shortest previous space length. 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 prepits or prepits.

FIG. 11 is a schematic diagram of an information processing apparatus using the optical disk drive shown in FIG.
The information processing apparatus includes a main control device, an interface, a recording device, an input device, a display device, and the like.
The main controller includes a CPU (central processing unit, microcomputer), a main memory (none of which are shown), and the like, and controls the entire host computer.
The interface is a two-way communication interface with the optical disc drive, and conforms to standard interfaces such as ATAPI and SCSI. The interface is connected to the optical disk drive interface 25 described above. The connection form between the interfaces may be not only a cable connection using a communication line such as a communication cable (for example, a SCSI cable) but also a wireless connection using infrared rays.

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

  According to the present invention, it is possible to record on a dye-based write-once DVD medium with low jitter and low error rate at any linear velocity, and can be manufactured more easily than the land pre-pit format used in DVD-R. The high-frequency wobble format can efficiently add data. 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 more concretely, this invention is not limited by these Examples.

Examples 1-9, Comparative Examples 1-6
On an injection molded polycarbonate substrate having a groove depth of 1750 mm, a half width of 0.33 μm, a track pitch of 0.74 μm, a guide groove corresponding to a wobble frequency of 32T, a thickness of 0.6 mm, and an outer diameter of 120 mm, The compound of formula 2] is weighed 60:40 by weight, dissolved in 2,2,3,3-tetrafluoro-1-propanol and spinner-coated to form an organic dye layer having a thickness of 1200 mm, and 85 Dry at 30 ° C. for 30 minutes.
Next, a reflective layer of silver 1100 mm is provided by sputtering, and further a protective layer having a thickness of 5 μm is provided thereon with an acrylic photopolymer, and then an injection molded polycarbonate flat substrate having a thickness of 0.6 mm and an outer diameter of 120 mm is formed. An optical recording medium was obtained by bonding 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. Then, recording was performed with a recording power that minimizes Bottom Jitter (bottom jitter), 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. W1 is the total power added and W2 is the power without additional power. Furthermore, although the pulse lengths of FIGS. 4 to 9 are used for the linear speeds of 21 m / s and 28 m / s, the present invention is not limited to this.
In Example 8, the cooling amount was 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 amount of light in the cooling portion was 0.7 mW, which was the same as the reproduction light power. That is, the recording waveform has no cooling pulse. In Comparative Example 2, the light quantity of the cooling part was 0.4 mW, which was larger than that of the present invention. In Comparative Example 3, the recording linear velocity was set to a high linear velocity without cooling as in Comparative Example 1.

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。

As can be seen from Table 2 above, Examples 1-8 are better in jitter and asymmetry than Comparative Examples 1-3.

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, 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 4 to 6, light was produced under the same production conditions as in the examples using the prototype condition stamper and molded substrate in which the size of LPPb in the LPP format implemented in DVD-R was changed (changed). Recording media were 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. Further, it was confirmed that when the LPPb is at a level lower than 0.16 as in Comparative Example 4, it is impossible to detect the address in the actually used apparatus.

(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 prior art example of the head part of a mark other than the shortest length mark for recording linear velocity of 28 m / s, and a rear end part addition type | mold light emission waveform. The figure which shows the prior art example of the head part of a mark other than the shortest length mark for recording linear velocity of 28 m / s, and a mark other than the next short mark, and a rear-end part addition type | mold light emission waveform. The figure which shows the example of this invention of the head part of a mark other than the shortest length mark for recording linear velocity of 28 m / s, and a rear end part addition type | mold light emission waveform. The figure which shows the example of this invention of the head part of a mark other than the shortest long mark for recording linear velocity of 28 m / s, and the next short mark, and a rear-end part addition type | mold light emission waveform. The figure which shows the example of this invention of the head part of a mark other than the shortest length mark for recording linear velocity of 21 m / s, and a rear end part addition type | mold light emission waveform. The figure which shows the example of this invention of the head part of a mark other than the shortest length mark for recording linear velocity 21m / s, and the next short mark, and a rear-end part addition type | mold light emission waveform. The functional block diagram which shows an example of the principal part structure of an optical disk drive. FIG. 11 is a schematic diagram of an information processing apparatus using the optical disc drive shown in FIG. 10.

Explanation of symbols

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 period n Integer greater than or equal to n ′ Integer greater than or equal to 3 ps Length of space immediately before cm Recording mark length W1 Additional power W2 No additional power

Claims (19)

  Heat each mark other than the shortest length mark or each mark other than the shortest length mark and the next shortest mark to the recording layer mainly composed of an organic dye formed on a substrate having a guide groove provided with a wobble. When recording with one pulse light whose output has been increased for a certain period of time at the beginning and rear end of the pulse, and reproducing the recording with the reproduction light, after recording all marks, An optical recording / reproducing method for a dye-based write-once DVD medium, characterized in that an irradiation light amount of a cooling pulse after the end is set to 0.1 mW or less for a certain time.   2. The optical recording / reproducing method according to claim 1, wherein the shortest length mark or the shortest length mark and the next shortest mark are always recorded with one pulsed light having a constant power.   3. The optical recording / reproducing method according to claim 2, wherein the pulsed light power having a constant power is made equal to the pulsed light power at two high outputs at the head and rear ends of the pulse.   The time for which the cooling pulse irradiation light quantity after the rear end of the pulse is 0.1 mW or less is set to a length of 1/6 to 6/6 of the shortest long space. Optical recording and playback method.   The head heating pulse width of the recording pulse train that forms the mark with the shortest space length immediately before is distinguished by whether the mark length is the shortest length, and the head heating pulse width of the shortest mark is the shortest length. The head heating pulse width of the recording pulse train that forms the shortest length mark is distinguished by whether the space length immediately before the shortest mark is the shortest length. 5. The head heating pulse width of the mark having the shortest preceding space length is set shorter than the head heating pulse width of the mark having the shortest preceding space length. Optical recording and playback method.   6. The optical recording / reproducing method according to claim 1, wherein the frequency of the wobble is a frequency corresponding to 4T to 96T, where T is a basic clock period.   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 / The optical recording / reproducing method according to claim 1, wherein synchronization is performed within a range of PP ≦ 0.4.   The optical recording / reproducing method according to claim 1, wherein the wavelength of the recording light is 600 to 720 nm.   The recording layer single layer has a refractive index n of 1.5 ≦ n ≦ 3.0 and an extinction coefficient k of 0.02 ≦ k ≦ with respect to the light in the wavelength range of the recording light and the reproducing light of ± 5 nm. 9. The optical recording / reproducing method according to claim 1, wherein the optical recording / reproducing method is 0.2.   The optical recording / reproducing method according to any one of claims 1 to 9, wherein the decomposition start temperature of the recording layer is 100 to 360 ° C.   The optical recording medium has at least one layer selected from a reflective layer, a protective layer, an adhesive layer, a protective substrate, and a substrate surface hard coat layer as a constituent layer other than the recording layer on the substrate. The optical recording / reproducing method according to any one of 1 to 10.   12. The optical recording / reproducing method according to claim 11, wherein the reflective layer is made of any one of gold, silver, and aluminum, or an alloy containing them as a main component.   13. The optical recording / reproducing method according to claim 11 or 12, wherein the protective layer is made of an ultraviolet curable resin.   An adhesive layer for bonding two substrates to form a double-sided recording medium is provided between the substrates, and the adhesive used for the adhesive layer is an ultraviolet curable resin. The optical recording / reproducing method according to any one of 11 to 13.   For write-once DVD media with wobbles in the guide groove of the substrate, place each mark other than the shortest length mark, or each mark other than the shortest length mark and the next shortest mark, at the beginning and rear end of the heating pulse. Is recorded with one pulse light whose output has been increased for a certain period of time, and when reproducing the recording with the reproduction light, at the time of the mark recording, the irradiation light amount of the cooling pulse after the pulse rear end of all the marks, A recording / reproducing apparatus for a dye-based write-once DVD medium, characterized by having a function of making the constant time 0.1 mW or less.   16. The recording / reproducing apparatus according to claim 15, wherein the recording / reproducing apparatus has a function of always recording the shortest length mark or the shortest length mark and the next shortest mark with one pulsed light having a constant power.   17. The recording / reproducing apparatus according to claim 15, wherein the recording / reproducing apparatus has a function of equalizing the pulsed light power of a constant power and the pulsed light power of two high outputs at the head part and the rear end part of the pulse.   18. The method according to any one of claims 15 to 17, wherein the cooling pulse irradiation light quantity after the rear end of the pulse has a function of setting the length of 1/6 to 6/6 of the shortest long space. A recording / reproducing apparatus according to claim 1. For write-once DVD media having wobbles in the guide groove of the substrate, the head heating pulse width of the recording pulse train that forms the mark with the shortest preceding space length is set whether the mark length is the shortest length. The head heating pulse width of the shortest length mark is set longer than the head heating pulse width of the non-shortest length mark, and the head heating pulse width of the recording pulse train forming the shortest length mark is The head heating pulse width of the mark with the shortest previous space length is set shorter than the head heating pulse width of the mark with the shortest previous space length. The recording / reproducing apparatus according to claim 15, which has a function.

Images