JP2009064531A - Recording method, write-once multilayer optical recording medium, program, recording medium, information recording device and information recording system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly record information in a write-once multilayer optical recording medium having a plurality of recording layers. <P>SOLUTION: If optimum recording power in a first information layer L0 where user data is first recorded is not decided in recording user data in an optical disk 15 being a write-once double-layer optical recording medium compatible with a blue laser, it is decided by OPC in the first information layer L0 (steps S403 to S413). When a second information layer L1 is to be recorded, optimum recording power in the second information layer L1 is calculated from the optimum recording power in the first information layer L0, and information is recorded in the second information layer L1 by using optimum recording power in the second information layer L1. Thus, test recording in the second information layer L1 becomes unnecessary and thus information can be quickly recorded in the second information layer L1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording method, a write once multi-layer optical recording medium, a program, a recording medium, an information recording apparatus, and an information recording system. More specifically, the present invention uses a laser beam for a write once multi-layer optical recording medium having a plurality of recording layers. A recording method for recording information, a write once multilayer optical recording medium having a plurality of recording layers, a program used in an information recording apparatus capable of recording information on a write once multilayer optical recording medium having a plurality of recording layers, and the program The present invention relates to a recorded recording medium, an information recording apparatus capable of recording information on a write-once multi-layer optical recording medium having a plurality of recording layers, and an information recording system including the information recording apparatus.

  The write-once optical recording medium generally has a configuration in which a recording layer made of an inorganic or organic material is provided on a plastic substrate, and a reflective layer that improves the light absorption rate of the recording layer and has a thermal diffusion effect is provided thereon. Basically, information is recorded and reproduced by irradiating a laser beam from the substrate surface side. For example, when recording information, the refractive index of the organic material is changed by laser light irradiation to form a recording mark.

  In recent years, the amount of information handled by computers and the like has increased, so it supports the wavelength of blue lasers used in write-once optical recording media such as HD DVD (High Definition DVD) -R and BD (Blu-ray Disc) -R. Research on recording materials to be used and development of write-once optical recording media themselves are actively conducted. The aim is to make the spot size smaller, increase the recording capacity, and increase the information density by reducing the diffraction limit or increasing the numerical aperture of the objective lens with respect to the wavelength of the blue laser.

  As a method for improving the optical recording medium itself to increase the recording capacity, various two-layer optical recording media prepared by bonding two information layers each having a recording layer with an ultraviolet curable resin or the like have been proposed. The separation layer (also referred to as an intermediate layer), which is an adhesive portion between the information layers, has a function of optically separating the two information layers, and laser light used for recording and reproduction is applied to the information layer as far back as possible. Since it needs to reach, it is made of a material that does not absorb laser light as much as possible. Furthermore, a multilayer optical recording medium having three or four recording layers has been developed by applying a production process of a two-layer optical recording medium.

  A method for determining an optimum recording power in an optical recording medium is known as OPC (Optimum Power Control). For example, Patent Documents 1 to 3 disclose OPC in a multilayer optical recording medium. In these OPC methods, when determining the optimum power of each recording layer, the recording condition is read from the wobble signal in each recording layer, and then test recording is always performed in that recording layer.

  Patent Document 4 discloses a two-layer DVD + R.

  Patent Document 5 discloses a recording method for a single-layer DVD-R using an organic dye material as a recording layer.

  In Patent Document 6, as a recording method for forming an irreversible recording mark by irradiating a recording layer made of an inorganic material of a write-once optical recording medium with a laser beam having a wavelength range of 200 to 450 nm, A recording method using pulses is disclosed.

JP 2004-295948 A JP 2004-310997 A JP 2006-127752 A JP 2006-252750 A JP 2004-152401 A JP 2007-004983 A

  By the way, as the recording capacity of the write once multi-layer optical recording medium having a plurality of recording layers increases, there is an increasing demand for shortening the time required for recording.

  The present invention has been made under such circumstances, and a first object thereof is to provide a recording method capable of quickly recording information on a write-once type multilayer optical recording medium having a plurality of recording layers. There is to do.

  A second object of the present invention is to provide a write-once type multilayer optical recording medium capable of recording information quickly.

  A third object of the present invention is executed by a control computer of an information recording apparatus, and enables information to be recorded quickly on a write once multilayer optical recording medium having a plurality of recording layers. An object is to provide a program and a recording medium on which the program is recorded.

  A fourth object of the present invention is to provide an information recording apparatus and an information recording system capable of quickly recording information on a write once multi-layer optical recording medium having a plurality of recording layers.

  From a first viewpoint, the present invention is a recording method for recording information on a write-once type multilayer optical recording medium having a plurality of recording layers using a laser beam. When recording is performed on a recording layer other than the specific recording layer that is the recording layer, the optimum recording power in the specific recording layer and the optimum in the target recording layer that is the recording layer to be recorded are recorded. Calculating the optimum recording power in the target recording layer from the known optimum recording power in the specific recording layer using known coefficient information indicating a relationship with a proper recording power; And recording with respect to the target recording layer using the optimum recording power.

  According to this, when recording is performed on a recording layer other than the specific recording layer among the plurality of recording layers, the optimum recording power in the specific recording layer and the target recording layer that is the recording layer to be recorded are recorded. Using the known coefficient information indicating the relationship with the optimum recording power, the optimum recording power in the target recording layer is calculated from the optimum recording power in the known specific recording layer, and the optimum in the target recording layer is calculated. Recording is performed on the target recording layer using a suitable recording power. Therefore, test recording on the target recording layer is not required, and as a result, information recording on the target recording layer can be performed more quickly than before. Further, in the recording layers other than the specific recording layer among the plurality of recording layers, an area for test recording becomes unnecessary, and the recording area can be used effectively.

  According to a second aspect of the present invention, there is provided a write-once type multilayer optical recording medium having a plurality of recording layers, the specific recording layer being a recording layer in which user data is first recorded among the plurality of recording layers. Is a write-once multi-layer in which coefficient information indicating the relationship between the optimum recording power of the recording layer and the optimum recording power in a recording layer excluding the specific recording layer among the plurality of recording layers is recorded in advance on the specific recording layer It is an optical recording medium.

  According to this, the optimum recording power in the recording layers excluding the specific recording layer among the plurality of recording layers can be calculated from the optimum recording power in the specific recording layer. Therefore, when recording is performed on a recording layer other than the specific recording layer among a plurality of recording layers, test recording becomes unnecessary, and as a result, information recording on the target recording layer can be performed more quickly than before. It becomes. Further, in the recording layers other than the specific recording layer among the plurality of recording layers, an area for test recording becomes unnecessary, and the recording area can be used effectively.

  According to a third aspect of the present invention, there is provided a program for use in an information recording apparatus capable of recording information on a write-once multi-layer optical recording medium having a plurality of recording layers. When recording is performed on a recording layer other than the specific recording layer that is the recording layer, the optimum recording power in the specific recording layer and the optimum in the target recording layer that is the recording layer to be recorded are recorded. A procedure for calculating the optimum recording power in the target recording layer from the known optimum recording power in the specific recording layer using known coefficient information indicating a relationship with a proper recording power; The program for causing the control computer of the information recording apparatus to execute a procedure for performing recording on the target recording layer using the optimal recording power.

  According to this, when the program of the present invention is loaded into a predetermined memory and the start address is set in the program counter, the control computer of the information recording apparatus records the recording layers other than the specific recording layer among the plurality of recording layers. When recording is performed on a layer, using known coefficient information indicating the relationship between the optimum recording power in the specific recording layer and the optimum recording power in the target recording layer that is the recording layer to be recorded. Then, the optimum recording power in the target recording layer is calculated from the optimum recording power in the known specific recording layer. Then, recording is performed on the target recording layer using the optimum recording power in the target recording layer. In this case, test recording on the target recording layer is unnecessary, and as a result, information recording on the target recording layer can be performed more quickly than in the past. Further, in the recording layers other than the specific recording layer among the plurality of recording layers, an area for test recording becomes unnecessary, and the recording area can be used effectively.

  From the fourth viewpoint, the present invention is a computer-readable recording medium on which the program of the present invention is recorded.

  According to this, since the program of the present invention is recorded, it is possible to record information more quickly than before by causing the computer to execute it.

  From a fifth aspect, the present invention is an information recording apparatus capable of recording information on a write once multi-layer optical recording medium having a plurality of recording layers, an optical pickup apparatus; and user data among the plurality of recording layers When recording is performed on a recording layer other than the specific recording layer that is the first recording layer, the optimum recording power in the specific recording layer and the target recording layer that is the recording layer on which recording is performed A processing device that calculates the optimum recording power in the target recording layer from the known optimum recording power in the specific recording layer using known coefficient information indicating the relationship with the optimum recording power of An information recording device.

  According to this, when recording is performed on a recording layer other than the specific recording layer among the plurality of recording layers, the recording layer is an optimal recording power and recording on the specific recording layer by the processing device. Using the known coefficient information indicating the relationship with the optimum recording power in the target recording layer, the optimum recording power in the target recording layer is calculated from the optimum recording power in the known specific recording layer. In this case, test recording on the target recording layer is unnecessary, and as a result, information recording on the target recording layer can be performed more quickly than in the past. Further, in the recording layers other than the specific recording layer among the plurality of recording layers, an area for test recording becomes unnecessary, and the recording area can be used effectively.

  According to a sixth aspect of the present invention, there is provided an information recording system capable of recording information on a write once multilayer optical recording medium having a plurality of recording layers, the information recording apparatus of the present invention; and controlling the information recording apparatus And an information recording system.

  According to this, since the information recording apparatus of the present invention is provided, as a result, information recording on the target recording layer can be performed more quickly than in the past.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an information recording system 1 according to an embodiment of the present invention. The information recording system 1 includes an optical disk device 20 as an information recording device and a host device 90 (for example, a personal computer) as a control device.

"Optical disk device"
As shown in FIG. 1 as an example, this optical disc apparatus 20 includes a spindle motor 22 for rotating the optical disc 15, an optical pickup device 23, and a seek for driving the optical pickup device 23 in the radial direction of the optical disc 15. A motor 21, a laser control circuit 24, an encoder 25, a drive control circuit 26, a reproduction signal processing circuit 28, a buffer RAM 34, a buffer manager 37, an interface 38, a flash memory 39, a CPU 40, and a RAM 41 are provided. Note that the arrows in FIG. 1 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block. In the present embodiment, it is assumed that the optical disc apparatus 20 is compatible with a write-once multilayer disc.

  The optical pickup device 23 includes a light source including a semiconductor laser that emits blue laser light having a wavelength of 400 nm, an optical system that includes an objective lens and guides the laser light from the light source to the optical disk 15, and the like. Among the plurality of recording layers, the laser beam is focused on a recording layer to be accessed (hereinafter abbreviated as “target recording layer” for convenience), the reflected light from the optical disk 15 is received, and a plurality of photoelectric conversion signals are converted. Output.

  The reproduction signal processing circuit 28 acquires a servo signal (focus error signal, track error signal, etc.), address information, synchronization information, RF signal, etc. based on the output signal (a plurality of photoelectric conversion signals) of the optical pickup device 23. . The servo signal obtained by the reproduction signal processing circuit 28 is output to the drive control circuit 26, the address information is output to the CPU 40, and the synchronization signal is output to the encoder 25, the drive control circuit 26, and the like. Further, the reproduction signal processing circuit 28 performs a decoding process and an error detection process on the RF signal. When an error is detected, the reproduction signal processing circuit 28 performs an error correction process and then stores the reproduction data in the buffer RAM 34 via the buffer manager 37. Store. The address information included in the reproduction data is output to the CPU 40.

  The drive control circuit 26 generates a signal for correcting the positional deviation of the objective lens with respect to the tracking direction based on the track error signal from the reproduction signal processing circuit 28. Further, the drive control circuit 26 generates a signal for correcting the focus shift of the objective lens based on the focus error signal from the reproduction signal processing circuit 28. Each signal generated here is output to the optical pickup device 23. Thereby, tracking control and focus control are performed. Furthermore, the drive control circuit 26 generates a drive signal for driving the seek motor 21 and a drive signal for driving the spindle motor 22 based on an instruction from the CPU 40. The drive signal of each motor is output to the seek motor 21 and the spindle motor 22, respectively.

  The buffer RAM 34 temporarily stores data to be recorded on the optical disk 15 (recording data), data reproduced from the optical disk 15 (reproduction data), and the like. Data input / output to / from the buffer RAM 34 is managed by a buffer manager 37.

  Based on an instruction from the CPU 40, the encoder 25 takes out the recording data stored in the buffer RAM 34 through the buffer manager 37, modulates the data, adds an error correction code, and the like, and outputs a write signal to the optical disc 15. Generate. The write signal generated here is output to the laser control circuit 24.

  The laser control circuit 24 controls the light emission power of the semiconductor laser. For example, during recording, the laser control circuit 24 generates a semiconductor laser drive signal based on the write signal, the recording conditions, the light emission characteristics of the semiconductor laser, and the like.

  The interface 38 is a bidirectional communication interface with the host device 90 and conforms to standard interfaces such as ATAPI (AT Attachment Packet Interface), SCSI (Small Computer System Interface), and USB (Universal Serial Bus).

  The flash memory 39 stores various programs including a program according to an embodiment of the present invention described by a code readable by the CPU 40, light emission characteristics of the semiconductor laser, and the like.

  The CPU 40 controls the operation of each unit in accordance with the program stored in the flash memory 39 and saves data necessary for control in the RAM 41 and the buffer RAM 34.

"Host device"
As shown in FIG. 2 as an example, the host device 90 includes a main control device 92, a hard disk device (HDD) 94, an input device 95, a display device 96, a drive interface 97, and the like.

  The HDD 94 includes a hard disk 94b and a drive device 94a for driving the hard disk 94b.

  The display device 96 includes a display unit (not shown) using, for example, a CRT, a liquid crystal display (LCD), a plasma display panel (PDP), and the like, and displays various information instructed from the main control device 92.

  The input device 95 includes at least one input medium (not shown) such as a keyboard, a mouse, a tablet, a light pen, and a touch panel, for example, and notifies the main control device 92 of various information input by the user. Note that information from the input medium may be input in a wireless manner. In addition, an example in which the display device 96 and the input device 95 are integrated includes an LCD with a touch panel.

  The drive interface 97 is a bidirectional interface between the main control device 92, the optical disc device 20, and the HDD 94, and conforms to the same standard interface as the interface 38 of the optical disc device 20.

"optical disk"
As shown in FIG. 3 as an example, the optical disk 15 includes a first substrate M0, a first information layer L0, an intermediate layer ML, a second information layer L1, and a second substrate M1 in this order from the laser beam incident side. is doing. That is, the optical disk 15 is a two-layer disk. Here, as an example, the optical disk 15 is assumed to be a write-once type optical recording medium corresponding to a so-called blue laser. And user data shall be recorded on the 1st information layer L0 first. Furthermore, an appropriate linear velocity for recording user data on the optical disc 15 is in the range of 4 m / S to 14 m / S.

<< First substrate M0 >>
The first substrate M0 needs to sufficiently transmit laser light irradiated for recording and reproduction, and those conventionally known in the technical field are applied. As the material, glass, ceramics, or resin is usually used, and resin is particularly preferable in terms of moldability and cost.

  Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicon resin, fluorine resin, ABS resin, and urethane resin. Acrylic resins such as polycarbonate resin and polymethyl methacrylate (PMMA), which are excellent in terms of moldability, optical characteristics, and cost, are preferable.

  On the surface of the first substrate M0 on which the first information layer L0 is formed, there are spiral or concentric meandering grooves for tracking, and uneven patterns called land portions and groove portions are formed. Usually, the groove is transferred by a stamper attached in a mold, such as an injection molding method or a photopolymer method, and the first substrate M0 is molded. The thickness of the first substrate M0 is preferably about 70 to 590 μm.

<< first information layer L0 >>
The first information layer L0 includes an undercoat layer L0 ₁ , a recording layer L0 ₂ , a first overcoat layer L0 ₃ , and a second overcoat layer L0 ₄ in order from the laser light incident side.

The recording layer L0 ₂ is bismuth (Bi) and / or inorganic material mainly composed of Bi oxide is used.

  By the way, in the write-once type optical recording medium having a plurality of information layers, when an organic material is used for the recording layer, the information layer on the incident side of the laser beam (hereinafter also referred to as “the information layer on the near side” for convenience) (1) recording layer / reflective layer, (2) undercoat layer / recording layer / reflective layer, (3) subbing layer / recording layer / overcoat layer / reflective layer, etc. is doing. As a material for this reflective layer, metals such as silver (Ag), copper (Cu), aluminum (Al), titanium (Ti), and alloys thereof are used. Since the information layer on the near side is required to have a certain degree of light transmittance, in the configurations (1) to (3), the reflective layer having a high absorption coefficient is made thin and a translucent film. It is necessary to.

  On the other hand, the inorganic material mainly composed of Bi and / or Bi oxide has a higher reflectance than that of a conventional organic material, and thus it is not necessary to use a reflective layer having a high absorption coefficient. Therefore, it is not necessary to consider a loss due to optical absorption in the reflective layer, and a high light transmittance can be ensured.

Other metal elements contained in the recording layer L0 _2, boron (B), carbon (C), Cu, etc. germanium (Ge) are preferred. This is effective to raise the absorption efficiency of the recording layer L0 _2, it is possible to improve the recording characteristics and recording sensitivity. In particular the absorption coefficient of the recording layer L0 ₂ is preferably in the range of 0.3 to 0.9.

For the undercoat layer L0 ₁ , the first overcoat layer L0 ₃ , and the second overcoat layer L0 ₄ , a transparent conductive film or a transparent dielectric film having a low absorption coefficient is used.

The first upper sublayer L0 _3, through improving the transparent light, and is better made of material higher than that of the recording layer L0 ₂ mp.

The second upper coating layer L0 _4, higher absorption than the first upper sublayer L0 _3, and to transmit the light to the second information layer L1, it is made of less as possible absorbing materials. Thereby, it is possible to improve the recording sensitivity.

Further, as the optical constants of the second upper coating layer L0 _4, the refractive index of 2.0 or more, 2.4 or less, the absorption coefficient is 0.05 or more, by 0.20 or less, the recording of the recording layer L0 ₂ There is an effect of improving sensitivity and recording characteristics.

As a specific material used for the second upper coating layer L0 _4, niobium (Nb), indium (In), zinc (Zn), tin (Sn), silicon (Si), Al, tungsten (W), manganese Of (Mn), it is preferable to comprise at least one oxide.

Undercoat layer L0 ₁ and the first upper sublayer L0 ₃ is passed through well clear light, and preferably has a melting point having a higher material than the recording layer L0 _2, deterioration of the recording layer L0 _2, to prevent alteration, enhancing the adhesive strength between the recording layer L0 _2, and as it has the effect of such increase recording characteristics, the metal oxides, nitrides, sulfides, etc. carbides are mainly used.

Specific examples include metal oxides such as SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₃ , TiO ₂ , In ₂ O ₃ , MgO, and ZrO ₂ , Si ₃ N ₄ , AlN, TiN, BN, ZrN, and the like. Nitrides, sulfides such as ZnS, In ₂ S ₃ , and TaS ₄ , carbides such as SiC, TaC, B ₄ C, WC, TiC, and ZrC, diamond-like carbon, or a mixture thereof.

These materials can be used alone as a protective film, but they may be mixed with each other. Further, impurities may be included as necessary. For example, a mixture of ZnS and SiO _{2 or} a mixture of Ta ₂ O ₅ and SiO ₂ can be used. In particular, ZnS—SiO ₂ is often used. In this case, the mixing ratio is most preferably ZnS: SiO ₂ = 80: 20 (molar ratio). This material has a high refractive index n, because it is the extinction coefficient k is approximately zero, it is possible to increase the absorption efficiency of the recording layer L0 ₂ light and generated by light absorption for low thermal conductivity thermal it is possible to suppress the diffusion moderately, it is possible to increase the temperature of the recording layer L0 ₂ until meltable temperature.

It is also possible to sandwich the _Al 2 _{O 3} between the first substrate M0 and undercoat layer L0 _1. Thereby, since substrate noise can be suppressed, recording characteristics are improved.

《Middle layer ML》
The intermediate layer ML preferably has small light absorption at the wavelength of the laser beam irradiated for recording and reproduction, and the material is preferably a resin in terms of moldability and cost, and an ultraviolet (UV) curable resin. A slow-acting resin, a thermoplastic resin, or the like can be used.

  The intermediate layer ML allows the optical pickup device 20 to discriminate between the first information layer L0 and the second information layer L1 when recording and reproducing, and has a thickness of 20 ˜30 μm is preferred. When the thickness is less than 20 μm, crosstalk between information layers occurs. On the other hand, when the thickness is larger than 30 μm, spherical aberration occurs when recording and reproducing on the second information layer L1, and recording and reproduction tend to be difficult.

<< 2nd information layer L1 >>
The second information layer L1 includes an undercoat layer L1 ₁ , a recording layer L1 ₂ , an overcoat layer L1 ₃ , and a reflective layer L1 ₄ in this order from the laser light incident side.

The undercoat layer L1 _1, the upper coating layer L1 _3, through improving the transparent light, and preferably has a melting point having a higher material than the recording layer L1 _2, deterioration of the recording layer L1 _2, to prevent alteration, recording enhancing the adhesive strength between the layers L1 _2, and as it has the effect of such increase recording characteristics, the metal oxides, nitrides, sulfides, etc. carbides are mainly used.

Specific examples include metal oxides such as SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₃ , TiO ₂ , In ₂ O ₃ , MgO, and ZrO ₂ , Si ₃ N ₄ , AlN, TiN, BN, ZrN, and the like. Nitrides, sulfides such as ZnS, In ₂ S ₃ , TaS ₄ , carbides such as SiC, TaC, B ₄ C, WC, TiC, ZrC, diamond-like carbon, or a mixture thereof. These materials can be used alone or as a mixture with each other. Further, impurities may be included as necessary.

For example, a mixture of ZnS and SiO ₂ or Ta ₂ O ₅ can be used. In particular, ZnS—SiO ₂ is often used. In this case, the mixing ratio is most preferably ZnS: SiO ₂ = 80: 20 (molar ratio). Heat this material, the refractive index n is high, because it is the extinction coefficient k is approximately zero, which can increase the absorption efficiency of the recording layer L1 ₂ light and generated by light absorption for low thermal conductivity it is possible to suppress the diffusion moderately, it is possible to increase the temperature of the recording layer L1 ₂ until meltable temperature.

The film thickness of the upper coating layer L1 ₃ is preferably in the range of 20 to 100 nm. If it is thinner than 20 nm, the residual heat hardly stays in the recording layer, and the recording sensitivity deteriorates. On the other hand, if it is thicker than 100 nm, the film formation time becomes long and there is a risk of causing thermal damage to the second substrate M1.

Undercoat layer L1 ₁ of the film thickness is preferably in the range of 50～90Nm.

As the material of the reflective layer L1 _4, it is possible to use Ag, Cu, Al, and gold (Au), and alloys thereof. There is no need to transmit light, reflective layer L1 ₄ good as a thick film.

When Ag is used in the reflective layer L1 _4, it is preferable to insert an interface layer such as TiC-TiO ₂ between the upper coating layer L1 ₃ and the reflective layer L1 _4. This is to prevent the formation of Ag ₂ S by reacting S of ZnS—SiO ₂ with Ag. If Ag ₂ S is formed, the storage characteristics of the recording medium may be deteriorated.

Thickness of the reflective layer L1 ₄ is preferably in the range of 40 to 80 nm. If the thickness is less than 40 nm, the thermal conductivity starts to decrease, and the signal quality deteriorates. If it is thicker than 80 nm, no further effect can be obtained even if it is thicker.

Recording layer L1 ₂ may be used a recording layer made of a material having the same composition ratio and the recording layer L0 ₂ of the first information layer M0, the recording sensitivity and reflectance, taking into consideration the characteristics such as modulation degree , the recording layer L0 ₂ of the first information layer M0 may use different recording layer composition ratios.

The film thickness of the recording layer L1 ₂ is preferably in the range of 3 to 20 nm. If it is thinner than 3 nm, the recording sensitivity deteriorates, and if it is thicker than 20 nm, the recording characteristics deteriorate.

<< Second substrate M1 >>
As the material of the second substrate M1, the same material as that of the first substrate M0 may be used, but a material opaque to light may be used, and the material and the groove shape are different from those of the first substrate M0. Also good. The thickness of the second substrate M1 is not particularly limited, but it is preferable to select the thickness so that the total thickness with the first substrate M0 is 1.2 mm.

  The optical disk 15 is usually manufactured through a film forming process and an adhesion process.

  In the film forming step, the first information layer L0 is formed on the surface of the first substrate M0 provided with the groove, and the second information layer L1 is formed on the surface of the second substrate M1 provided with the groove. The first information layer L0 and the second information layer L1 are formed by various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating, electron beam deposition, and the like. Can do. Among these, the sputtering method is excellent in mass productivity and film quality. In this sputtering method, film formation is generally performed while flowing an inert gas such as argon. At this time, reactive sputtering may be performed while oxygen, nitrogen, or the like is mixed.

  In the adhesion process, the first information layer L0 formed on the first substrate M0 and the second information layer L1 formed on the second substrate M1 face each other and are bonded together via the intermediate layer ML. For example, the UV resin is applied to one surface of the first information layer L0 and the second information layer L1, the information layer surfaces are faced to each other, both substrates are pressurized, and the UV resin is cured by irradiating ultraviolet rays.

《Recording strategy》
In the recording layer L0 ₂ of the first information layers L0, various recording conditions on the inner peripheral side is pre-recorded (pre-formatted).

  As an example, in FIG. 4, each recording layer has a recording mark having a length corresponding to n × Tw (n: integer of 3 or more, Tw: period of channel clock Wck) (hereinafter also referred to as “nTw recording mark” for convenience). ) Is shown as a recording strategy.

  Here, the laser beam is first set to the power P1, to the power P2 after the time Ttop has elapsed, to the power P1 again after the time Tm has elapsed, and then to the power Pb (bias power) after the time Tlp has elapsed. The power is set to P3 after Tlc has elapsed. P1> P2> P3> Pb.

  FIG. 5 shows the relationship between Ttop, P1, and PRSNR (Partial Response Signal to Noise Ratio) when the recording linear velocity v is double speed (13.22 m / s). When Ttop is 1.0 Tw or more and 1.7 Tw or less, a high PRSNR can be realized with a small power P1. If Ttop is out of this range, the mark shape and the deviation between codes occur, and the recording characteristics deteriorate.

  The PRSNR is an index that can simultaneously represent the S / N (signal-to-noise ratio) of the reproduced signal and the actual reproduced waveform and the theoretical PR waveform linearity, and is necessary for estimating the bit error rate. Is one of the key indicators. In the conventional DVD, the jitter value (fluctuation component in the time direction) of the reproduction signal obtained from the optical pickup device is defined as a standard as one of the indexes for evaluating the characteristics of the optical disc and the optical pickup device. Since it is difficult to evaluate the characteristics with the jitter value of the conventional method due to the large capacity and high density, special processing is performed on the amplitude information obtained from the playback waveform to create the target signal and the actual playback signal. The difference was normalized as PRSNR. This PRSNR is one of the evaluation items indispensable for producing an optical disc for HD DVD and an optical pickup device.

  FIG. 6 shows the relationship between P1 and PRSNR in the first information layer L0 when the recording linear velocity v is double speed (13.22 m / s). FIG. 7 shows the relationship between P1 and PRSNR in the second information layer L1 when the recording linear velocity v is double speed (13.22 m / s). The value obtained by adding Ttop, Tm, and Tlp is preferably (n−0.25) × Tw or more and n × Tw or less. In this case, the recording mark can be formed at a desired position and with a desired length, and the disturbance between codes can be reduced. The desired recording sensitivity can be ensured. If the value obtained by adding Ttop, Tm, and Tlp is smaller than (n−0.25) × Tw, the recording sensitivity changes by 5% or more, which is not preferable.

  As an example, FIG. 8 shows a recording strategy when a recording mark having a length corresponding to 2 × Tw (hereinafter also referred to as “2Tw recording mark” for convenience) is formed on each recording layer.

  Here, the laser beam is first set to the power P1, then to the power Pb after the lapse of the time T2, and then to the power P3 after the lapse of the time Tlc.

  T2 is preferably 1.75 Tw or more and 2.1 Tw or less. Since the 2Tw recording mark has the highest appearance probability, it greatly affects the recording characteristics. Therefore, when T2 is out of the above range, since the fluctuation of the reproduction signal level becomes remarkable, the fluctuation of asymmetry becomes severe, which is not preferable. Patent Document 4 describes that the pulse length of the shortest mark is particularly preferably 25/16 to 48/16 times the basic clock period. However, Patent Document 4 does not describe the shortest length mark (2T) corresponding to a format for recording with a blue laser, and does not disclose a method for realizing high-density recording compatible with a blue laser.

  Both Tlp and Tlc are preferably 0.5 Tw or more and 1.1 Tw or less. When Tlp and Tlc are out of this range, the shape of the recording mark does not become a desired shape, a shift between codes occurs, and the recording characteristics deteriorate. Tlc is provided to promote escape of residual heat generated by laser light irradiation, and is particularly important because the escape speed is slow in the first information layer L0.

Ttop, Tm, Tlp, Tcp, T2 is included in ADIP information on the inner peripheral side of the recording layer L0 ₂ are previously recorded (preformatted).

Of the recording layer L0 _2, the optimum value of the power P1 P10, the optimal value of the power P2 P20, the optimal value of the power P3 and P30, on the recording layer L1 _2, the optimum value of the power P1 P11, the power P2 the optimum values P21, the optimal value of the power P3 when the P31, the coefficient in a following expression (1) to (3) [alpha] 1, [alpha] 2, .alpha.3 is included in ADIP information on the inner peripheral side of the recording layer L0 ₂ And recorded in advance (preformat).

P11 = α1 × P10 (1)
P21 = α2 × P20 (2)
P31 = α3 × P30 (3)

  FIG. 9A shows the relationship between the PRSNR and the value obtained by dividing P10 by P20 (ω1) when the recording linear velocity v is double speed (13.22 m / s). ω1 is preferably 1.03 or more and 1.29 or less, with a PRSNR of 15 or more.

  FIG. 9B shows the relationship between the PRSNR and the value obtained by dividing P11 by P21 (ω2) when the recording linear velocity v is double speed (13.22 m / s). ω2 is preferably 0.98 or more and 1.26 or less, with a PRSNR of 15 or more.

  When ω1 and ω2 are smaller than the lower limit value, a long mark is formed longer than the desired mark length due to the influence of thermal interference. When ω1 and ω2 are larger than the upper limit value, a long mark is formed shorter than a desired mark length. On the other hand, when ω1 and ω2 are larger than the upper limit value, the mark width in the radial direction becomes small, and the modulation degree decreases (see FIGS. 10A and 10B).

  Further, ω1 is preferably set equal to or higher than ω2.

Prerecorded (preformat) is included in ADIP information on the inner peripheral side of the ω1 and ω2 also recording layer L0 _2.

  For comparison, FIG. 11 shows a recording strategy in which laser light is repeatedly controlled between power P1 and power Pb.

  In the following, for the sake of convenience, the recording strategy in this embodiment shown in FIGS. 4 and 8 is referred to as “St_A”, and the comparative recording strategy shown in FIG. 11 is referred to as “St_B”.

  FIG. 13 to FIG. 16 show PRSNR and SbER (Simulated bit Error Rate) when recording is performed under the conditions shown in FIG.

  FIG. 13 shows the relationship between P1 and PRSNR in the first information layer L0 when the recording linear velocity v is double speed (13.22 m / s). St_A has a smaller P1 when the PRSNR is maximized than St_B.

  FIG. 14 shows the relationship between P1 and SbER in the first information layer L0 when the recording linear velocity v is double speed (13.22 m / s). St_A has a smaller P1 when SbER is minimum than St_B.

  FIG. 15 shows the relationship between P1 and PRSNR in the second information layer L1 when the recording linear velocity v is double speed (13.22 m / s). St_A has a smaller P1 when the PRSNR is maximized than St_B.

  FIG. 16 shows the relationship between P1 and SbER in the second information layer L1 when the recording linear velocity v is double speed (13.22 m / s). St_A has a smaller P1 when SbER is minimum than St_B.

  That is, St_A can greatly improve the recording sensitivity while maintaining the recording characteristics as compared with St_B.

"Examples and comparative examples"
Next, an example and a comparative example will be described in detail.

  As an evaluation apparatus, ODU1000 manufactured by Pulstec Co., Ltd. was used, and the wavelength of the laser light irradiated when recording on the recording layer was 405 nm, and the numerical aperture NA of the objective lens was 0.65. The laser beam power during reproduction was 0.8 mW. MSG3 manufactured by Pulstec was used as the optical waveform generator.

Recording was performed on five tracks, and the center track (third track) was reproduced. Peak power, PRSNR, SbER, and I11 / I11H were obtained as evaluation items for recording characteristics. Peak power represents the optimum recording power, and 15 mW or less was accepted. The PRSNR is a signal quality when the HD-DVD signal processing method “PRML” is used, and 15 or more is accepted. SbER represents an error rate, and 0.00005 (5.0 × 10 ⁻⁵ ) or less was accepted. I11 / I11H represents the degree of modulation when the reflection intensity of the unrecorded portion is I11H, the reflectance of the recorded portion is I11L, and I11 = I11H−I11L, and 40% or more is regarded as acceptable.

  The write-once type two-layer optical recording medium used for the test was prepared as follows.

Sputtering power of 4 kW on a first substrate M0 made of a polycarbonate resin having a diameter of 12 cm and a thickness of 0.59 mm and having a tracking guide unevenness (groove depth of 30 nm) by meandering continuous grooves with a track pitch of 0.4 μm on one side. under Ar flow rate 15 sccm, an undercoat layer L0 ₁ thickness 50nm made of _ZnS-SiO 2 (80:20 mol%) was deposited by RF magnetron sputtering.

Next, using a target having a recording layer composition of Bi ₂ O ₃ —B ₂ O ₃ —B ₄ C under a sputtering power of 0.8 kW and an Ar flow rate of 15 sccm, the recording layer L 0 ₂ having a thickness of 8 nm is formed. The film was formed by RF magnetron sputtering.

Next, a sputtering power of 4 kW, under Ar flow rate 15 sccm, a _ZnS-SiO 2 first upper sublayer L0 ₃ of thickness 20nm made of (80:20 mol%) was deposited by RF magnetron sputtering.

Next, under a sputtering power of 2 kW and an Ar flow rate of 15 sccm, a 45 nm-thickness second overlayer L0 ₄ made of Nb ₂ O ₅ was formed by DC magnetron sputtering to form a first information layer L0. .

On the other hand, sputtering power is applied on the second substrate M1 made of a polycarbonate resin having a diameter of 12 cm and a thickness of 0.6 mm, and having a tracking guide unevenness (groove depth of 32 nm) by meandering continuous grooves with a track pitch of 0.4 μm on one side. Under the condition of 3 kW and an Ar flow rate of 20 sccm, a reflective layer L1 ₄ made of Ag-Bi (99.5: 0.5 wt%) and having a film thickness of 60 nm was formed by a DC magnetron sputtering method.

Next, an interface layer having a thickness of 4 nm made of TiC—TiO ₂ (70:30 mol%) was formed by a DC magnetron sputtering method under a sputtering power of 2 kW and an Ar flow rate of 15 sccm.

Next, a sputtering power of 4 kW, under Ar flow rate 15 sccm, a _ZnS-SiO 2 (80:20 mol%) undercoat layer L1 ₃ on the film thickness 90nm consisting deposited by RF magnetron sputtering.

Next, a sputtering power of 0.8 kW, under Ar flow rate 15 sccm, the Bi-O-B consisting of thickness 9nm recording layer L1 ₂ was deposited by RF magnetron sputtering.

Next, under the sputtering power of 4 kW and the Ar flow rate of 15 sccm, an undercoat layer L11 ₁ made of ZnS—SiO 2 (80:20 mol%) is formed by RF magnetron sputtering to form a second information layer. L1 was formed.

  The sputtering apparatus used was a DVD sprinter manufactured by Unaxis.

Then, manufactured by Nippon Kayaku Co. ultraviolet curing resin on the second upper coating layer L0 ₄ of the first information layer L0 (the KARAYAD DVD802) was applied, by bonding an undercoat layer L1 ₁ of the surface of the second information layer L1 A write-once two-layer optical recording medium having two information layers was prepared by spin coating and curing by irradiating ultraviolet rays from the first substrate M0 side to form an intermediate layer having a film thickness of 25 μm.

  Recording was performed on each information layer of the write-once two-layer optical recording medium at a recording linear velocity of 13.22 m / s using St_A shown in FIG.

In this case, when the optimum ω1 is studied by allocating power to the first information layer L0, PRSNR = 23 and SbER = 2.7 × 10 ⁻⁹ are obtained at ω1 = 1.17, and the optimum characteristics are obtained. Value (see FIG. 20). At this time, P1 = 13 mW, P2 = 11.1 mW, P3 = 5.4 mW, and Pb = 0.1 mW.

Further, when the optimum ω2 for the second information layer L1 is examined, PRSNR = 23.6 and SbER = 6.5 × 10 ⁻¹⁰ are obtained when ω2 = 1.12, and the optimum characteristic values are obtained. (See FIG. 21). At this time, P1 = 12.7 mW, P2 = 11.3 mW, P3 = 4.7 mW, and Pb = 0.1 mW.

  Since the first information layer L0 and the second information layer L1 have different layer configurations, there is a difference in the degree of thermal interference. Here, since the first information layer L0 has lower heat dissipation than the second information layer L1, it is preferable that ω1 ≧ ω2 as the magnitude relationship between ω1 and ω2 at which optimum characteristic values are obtained for each information layer.

  Next, recording was performed on each information layer of the write-once type two-layer optical recording medium at a recording linear velocity of 13.22 m / s using St_C shown in FIG. As an example, St_C is obtained by delaying the timing at which the power of the laser beam is set to P1 first by the time TSFP as compared with St_A, as shown in FIGS.

In this case, the optimum ω1 was studied by allocating power to the first information layer L0. As a result, PRSNR = 23.6 and SbER = 5.3 × 10 ⁻⁹ were obtained when ω1 = 1.21. It became a characteristic value. At this time, P1 = 13.5 mW, P2 = 11.2 mW, P3 = 5.4 mW, and Pb = 0.1 mW.

Further, when the optimum ω2 for the second information layer L1 was examined, ω2 = 1.18, PRSNR = 24.2, SbER = 6.6 × 10 ⁻⁹ were obtained, and the optimum characteristic values were obtained. . At this time, P1 = 12.0 mW, P2 = 10.2 mW, P3 = 3.7 mW, and Pb = 0.1 mW.

  P1 required to obtain a desired mark length differs between when St_A is used and when St_B is used. As TSFP is increased (Ttop + Tm + Tlp is decreased), a larger P1 is required. Since a sensitivity difference of about 4 to 6% occurs at TSFP = 0 to 0.25Tw, it is preferable to set the range of (n−0.25) × Tw ≦ Ttop + Tm + Tlp ≦ n × Tw.

<Recording process>
Next, processing in the optical disc device 20 when a recording request is received from the host device 90 will be described with reference to FIGS. 22 (A) and 22 (B). The flowcharts of FIGS. 22A and 22B correspond to a series of processing algorithms executed by the CPU 40.

  When the user inputs a recording request for the optical disc 15 via the input device 95, the main control device 92 of the host device 90 transmits a recording command and recording data to the optical disc device 20.

  When the optical disk apparatus 20 receives a recording command from the host apparatus 90, the start address of the program corresponding to the flowcharts of FIGS. 22A and 22B is set in the program counter of the CPU 40, and the process (recording process) is performed. Start.

  In the first step S401, the drive control circuit 26 is instructed to rotate the optical disc 15 at a predetermined linear velocity (or angular velocity), and the reproduction signal processing circuit 28 is notified that a recording command has been received from the host device 90. .

  In the next step S403, it is determined whether or not the optimum values P10, P20 and P30 of the recording power in the first information layer L0 have already been determined. Here, if P10, P20, and P30 are not stored in the RAM 41, the determination in step S403 is denied, and the process proceeds to step S405.

  In step S405, the first information layer L0 is set as an access target and notified to the drive control circuit 26, the reproduction signal processing circuit 28, and the like.

  In the next step S407, the recording conditions (ω1, ω2, Ttop, Tm, Tlp, Tcp, T2, etc.) in the first information layer L0 prerecorded (preformatted) in the first information layer L0 are changed to the optical pickup. The data is read out via the device 23 and the reproduction signal processing circuit 28 and stored in the RAM 41.

  In the next step S409, the coefficients α1, α2, and α3 recorded in advance (preformat) on the first information layer L0 are read out via the optical pickup device 23, the reproduction signal processing circuit 28, etc., and stored in the RAM 41. .

  In the next step S411, an OPC (Optimum Power Control) condition and a light emission waveform in the first information layer L0 are determined.

In the next step S413, the trial writing area provided in the recording layer _{L0 2 (PCA: Power Calibration Area} ) was used to implement the OPC, in the recording layer L0 _2, the optimum value P10 of the power P1, the power P2 The optimum value P20 and the optimum value P30 of the power P3 are determined. Here, the ratio between the power P1 and the power P2 is fixed, and the optimum values of the power P1 and the power P2 are first determined using one of the modulation degree and asymmetry obtained from the reproduction signal. Then, the power P1 and the power P2 are fixed to the optimum values, and the optimum value of the power P3 is determined using one of PRSNR and SbER obtained from the reproduction signal. In the case where the ratio β of power P3 and power P1 or the ratio γ of power P3 and power P2 is recorded in advance on the optical disc 15, the power P3 is calculated from the equation P3 = β × P1 or P3 = γ × P2. An optimum value may be determined.

  In the next step S417, it is determined whether or not the information layer to be recorded is the second information layer L1. If the information layer to be recorded is the second information layer L1, the determination here is affirmed and the process proceeds to step S419.

  In step S419, the second information layer L1 is set as an access target and notified to the drive control circuit 26, the reproduction signal processing circuit 28, and the like.

In the next step S421, the optimum value P11 of the power P1, the optimum value P21 of the power P2, and the optimum value P31 of the power P3 in the recording layer L12 ₂ are calculated based on the equations (1) to (3). .

  In the next step S423, a recording strategy is determined.

  In the next step S425, the drive control circuit 26 is instructed to form a light spot near the target position corresponding to the designated address. Thereby, a seek operation is performed. If the seek operation is unnecessary, the process here is skipped.

  In the next step S427, recording is permitted. Thus, the recording data from the higher-level device 90 is recorded with the optimum recording power on the information layer to be recorded by the encoder 25, the laser control circuit 24, the optical pickup device 23, and the like.

  In the next step S429, it is determined whether or not the recording is completed. If it is not completed, the determination here is denied and the determination is made again after a predetermined time has elapsed. If completed, the determination here is affirmed and the process proceeds to step S431.

  In step S431, the host device 90 is notified of the recording completion. Then, the recording process in the optical disc apparatus 20 ends.

  The main control device 92 of the host device 90 displays the recording result of the optical disc device 20 on the display unit of the display device 96 and notifies the user.

  On the other hand, if the information layer to be recorded is the first information layer L0 in step S417, the determination here is denied and the process proceeds to step S423.

  If P10, P20, and P30 are stored in the RAM 41 in step S403, the determination in step S403 is affirmed, and the process proceeds to step S417. That is, OPC in the first information layer L0 is not performed.

  23A and 23B show specific examples of the coefficients α1, α2, and α3 recorded (preformatted) in advance on the optical disc 15.

  As is clear from the above description, in the optical disc device 20 according to the present embodiment, a processing device is configured by the CPU 40 and a program executed by the CPU 40. It should be noted that at least a part of the processing according to the program by the CPU 40 may be configured by hardware, or all may be configured by hardware.

  In the present embodiment, the program according to the present invention is executed by the programs corresponding to FIGS. 22A and 22B among the programs recorded in the flash memory 39 as the recording medium. .

  In the present embodiment, the recording method according to the present invention is implemented in the recording process.

  As described above, according to the optical disc apparatus 20 according to the present embodiment, when user data is recorded on the optical disc 15 that is a write-once type two-layer optical recording medium corresponding to the blue laser, the user data is first recorded. If the optimum recording power in the first information layer L0 that is the information layer recorded on the first information layer L0 is not determined, the optimum recording power in the first information layer L0 is determined by OPC in the first information layer L0. . When the information layer to be recorded is the second information layer L1, the optimum recording power in the second information layer L1 is calculated from the optimum recording power in the first information layer L0 that has already been determined. Recording on the second information layer L1 is performed using the optimum recording power in the second information layer L1. Therefore, test recording on the second information layer L1 is not necessary, and as a result, information recording on the second information layer L1 can be performed more quickly than before. Further, in the second information layer L1, an area for test recording becomes unnecessary, and the recording area can be used effectively. Further, the recording strategy information recorded (preformatted) in advance on the optical disc 15 can be reduced as compared with the conventional case.

  In this case, since Ttop, Tm, Tlp, Tlc, and T2 can be the same for any information layer, the algorithm for determining the recording strategy can be simplified. Further, since the recording strategy information can be smaller than the conventional one, the register capacity in the laser control device 24 can be made smaller than the conventional one.

  Further, according to the information recording system 1 according to the present embodiment, since the optical disk device 20 is provided, as a result, it is possible to perform information recording on the second information layer L1 more quickly than before.

  Further, according to the optical disc 15 according to the present embodiment, since an inorganic material is used for each recording layer, good recording characteristics and modulation can be obtained in any recording layer. Further, since it is possible to efficiently absorb light into the recording layer while ensuring a high reflectance of the first information layer L0, stable recording and reproduction characteristics of the first information layer L0 can be obtained. This can be applied to, for example, an optical recording medium compatible with HD DVD-R DL and BD-R DL.

  In the recording process, the various information recorded in advance on the first information layer L0 of the optical disc 15 may be read when the optical disc 15 is set and stored in the RAM 41.

  Moreover, although the said embodiment demonstrated the case where the number of information layers was two, it is not limited to this, The number of information layers may be three or more. Even in this case, test recording may be performed only on the information layer in which user data is recorded first.

  In the above-described embodiment, the case where the recording layer on which user data is first recorded is a recording layer disposed at a position closest to the incident surface of the laser beam, such as HD DVD, is not limited to this. Instead, the recording layer on which user data is first recorded may be a recording layer disposed at a position farthest from the laser light incident surface, such as BD-R.

  In the above-described embodiment, the case where the optical pickup device includes one semiconductor laser has been described. However, the present invention is not limited to this. For example, a plurality of semiconductor lasers that emit light beams having different wavelengths may be included.

  In the above embodiment, the optical disc apparatus capable of recording and reproducing information has been described. However, the present invention is not limited to this, and any optical disc apparatus capable of recording at least information among recording, reproducing and erasing of information may be used. .

  In the above embodiment, the program according to the present invention is recorded in the flash memory 39, but is recorded in another recording medium (CD, magneto-optical disk, DVD, memory card, USB memory, flexible disk, etc.). May be. In this case, the program according to the present invention is loaded into the flash memory 39 via the playback device (or dedicated interface) corresponding to each recording medium. Further, the program according to the present invention may be transferred to the flash memory 39 via a network (LAN, intranet, Internet, etc.). In short, the program according to the present invention may be loaded into the flash memory 39.

  As described above, the recording method of the present invention is suitable for rapidly recording information on a write once multi-layer optical recording medium having a plurality of recording layers. Further, the write-once type multilayer optical recording medium of the present invention is suitable for quickly recording information. Further, the program and the recording medium of the present invention are suitable for causing the control computer of the information recording apparatus to quickly record information on a write-once multi-layer optical recording medium having a plurality of recording layers. . The information recording apparatus and information recording system of the present invention are suitable for quickly recording information on a write once multi-layer optical recording medium having a plurality of recording layers.

It is a block diagram which shows the structure of the information recording system which concerns on one Embodiment of this invention. It is a block diagram for demonstrating the structure of the high-order apparatus in FIG. It is a figure for demonstrating the structure of the optical disk which concerns on one Embodiment of this invention. It is a figure for demonstrating the light emission waveform in the case of forming the recording mark more than the length corresponding to 3Tw. It is a figure for demonstrating the range of the value which Ttop can take. It is a figure for demonstrating the relationship between P1 and PRSNR at the time of Ttop + Tm + Tlp = nTw in L0, and when Ttop + Tm + Tlp = (n-0.25) Tw. In L1, it is a figure for demonstrating the relationship between P1 and PRSNR at the time of Ttop + Tm + Tlp = nTw, and when Ttop + Tm + Tlp = (n-0.25) Tw. It is a figure for demonstrating the light emission waveform in the case of forming the recording mark of the length corresponding to 2Tw. FIG. 9A is a diagram for explaining a range of possible values of ω1, and FIG. 9B is a diagram for explaining a range of possible values of ω2. FIG. 10A is a diagram for explaining the relationship between ω1 and the modulation factor, and FIG. 10B is a diagram for explaining the relationship between ω2 and the modulation factor. It is a figure for demonstrating the comparative example of a light emission waveform. It is a figure for demonstrating the specific example of each parameter of a light emission waveform. It is a figure for demonstrating the relationship between P1 and PRSNR in L0 by the difference in the light emission waveform. It is a figure for demonstrating the relationship between P1 and SbER in L0 by the difference in the light emission waveform. It is a figure for demonstrating the relationship between P1 and PRSNR in L1 by the difference in the light emission waveform. It is a figure for demonstrating the relationship between P1 and SbER in L1 by the difference in the light emission waveform. It is a figure for demonstrating the light emission waveform in an Example. FIG. 18 is a light emission waveform diagram (part 1) for explaining St_C in FIG. 17; FIG. 18 is a light emission waveform diagram (part 2) for explaining St_C in FIG. 17; It is a figure for demonstrating Examples 1-10 and Comparative Examples 1-4. It is a figure for demonstrating Examples 11-23 and Comparative Examples 5 and 6. FIG. FIG. 6 is a flowchart (part 1) for explaining processing in the optical disc device when a recording request is received from a host device. FIG. FIG. 10 is a flowchart (part 2) for explaining processing in the optical disc device when a recording request is received from a higher-level device. FIG. 23A and FIG. 23B show the optimum recording power (P10, P20, P30) at L0, the coefficients (α1, α2, α3), and the optimum recording power (P11, P21, P3) at L1, respectively. It is a figure for demonstrating the specific example of P31).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Information recording system, 15 ... Optical disk (write-once type multilayer optical recording medium), 20 ... Optical disk apparatus (information recording apparatus), 23 ... Optical pick-up apparatus, 40 ... CPU (processing apparatus), 90 ... Host apparatus (control apparatus) , L0 ₂ ... recording layer (specific recording layer), L1 ₂ ... recording layer, P1 ... power (first power), P2 ... power (second power), P3 ... power (third power), Pb ... Power (fourth power), Tw ... cycle.

Claims (29)

A recording method for recording information using a laser beam on a write once multilayer optical recording medium having a plurality of recording layers,
When recording is performed on a recording layer other than the specific recording layer which is the recording layer on which user data is first recorded among the plurality of recording layers, optimum recording power and recording are performed in the specific recording layer. The optimum recording power in the target recording layer from the known optimum recording power in the specific recording layer using known coefficient information indicating the relationship with the optimum recording power in the target recording layer that is a recording layer. Calculating
Recording on the target recording layer using an optimum recording power in the target recording layer. Prior to the step of calculating the optimum recording power,
The method further includes the step of performing test recording on the specific recording layer when the optimum recording power in the specific recording layer is not determined, and determining the optimum recording power in the specific recording layer. The recording method according to claim 1 The step of calculating the optimum recording power includes:
Obtaining a coefficient corresponding to the target recording layer;
The recording method according to claim 1, further comprising a step of multiplying the optimum recording power in the specific recording layer by the coefficient. The coefficient is recorded in advance in the specific recording layer,
The recording method according to claim 3, wherein in the step of acquiring the coefficient, the coefficient is read from the specific recording layer. The power of the laser beam is controlled to a plurality of powers including a first power, a second power smaller than the first power, and a third power smaller than the second power at a predetermined timing. And
The recording method according to claim 1, wherein the optimum recording power includes optimum values of the first to third powers. A value obtained by dividing the first power by the second power in the specific recording layer is 1.03 or more and 1.29 or less,
The recording method according to claim 5, wherein a value obtained by dividing the first power by the second power in the target recording layer is 0.98 or more and 1.26 or less.   A value obtained by dividing the first power by the second power in the specific recording layer is not less than a value obtained by dividing the first power by the second power in the target recording layer. The recording method according to claim 6.   8. The recording according to claim 6, wherein each value obtained by dividing the first power by the second power in the plurality of recording layers is recorded in advance in the specific recording layer. Method. In the recording step, when the mark is formed, the laser beam is first set to the first power, the second power after the time Ttop has elapsed, and then the first power again after the time Tm has elapsed. Then, after the time Tlp elapses, the fourth power is smaller than the third power, and after the time Tlc elapses, the third power is obtained.
9. The recording method according to claim 5, wherein the time Ttop is 1.0 Tw or more and 1.7 Tw or less using a channel clock period Tw. The length of the mark is a length corresponding to n × Tw using an integer n of 3 or more,
The recording method according to claim 9, wherein a value obtained by adding the time Ttop, the time Tm, and the time Tlp is not less than (n−0.25) × Tw and not more than n × Tw.   11. The recording method according to claim 9, wherein values of the time Ttop, the time Tm, and the time Tlp are all recorded in advance in the specific recording layer. The step of calculating the optimum recording power includes:
Obtaining a known first coefficient, second coefficient, and third coefficient corresponding to the target recording layer;
In the specific recording layer, the optimum value of the first power is multiplied by the first coefficient, the optimum value of the second power is multiplied by the second coefficient, and the optimum value of the third power is obtained. The method according to claim 5, further comprising: multiplying a value by the third coefficient.   The recording method according to claim 12, wherein the first to third coefficients are recorded in advance in the specific recording layer. Prior to the step of calculating the appropriate recording power,
When optimum values of the first to third powers in the specific recording layer are not determined, test recording is performed on the specific recording layer, and the first to third powers in the specific recording layer are performed. The recording method according to claim 5, further comprising a step of determining an optimum value of each of the recording methods. The step of determining the optimum values respectively
Fixing the ratio of the first power to the second power and determining an optimum value of the first power and an optimum value of the second power;
The recording method according to claim 14, further comprising: fixing the first and second powers to respective optimum values and determining an optimum value of the third power. In the step of determining the optimum value of the first power and the optimum value of the second power,
16. The optimum value of the first power and the optimum value of the second power are respectively determined using one of a modulation factor and asymmetry obtained from a reproduction signal in the specific recording layer. The recording method described in 1. In the step of determining the optimum value of the third power,
The recording method according to claim 15 or 16, wherein an optimum value of the third power is determined using one of PRSNR and SbER obtained from a reproduction signal in the specific recording layer.   The specific recording layer is a recording layer disposed at a position closest to the laser light incident surface among the plurality of recording layers, and a position farthest from the laser light incident surface among the plurality of recording layers. The recording method according to claim 1, wherein the recording layer is any one of the recording layers disposed on the recording layer.   The recording method according to claim 1, wherein the laser beam is a laser beam having a wavelength of 400 nm.   20. The recording method according to claim 19, wherein in the recording step, recording is performed at a linear velocity within a range of 4 m / S to 14 m / S. A write once multilayer optical recording medium having a plurality of recording layers,
Optimal recording power in a specific recording layer that is a recording layer in which user data is first recorded among the plurality of recording layers, and optimal recording in a recording layer excluding the specific recording layer among the plurality of recording layers A write-once multi-layer optical recording medium in which coefficient information indicating a relationship with power is recorded in advance on the specific recording layer. Recording of information on the plurality of recording layers is performed using laser light,
The power of the laser beam is controlled to a plurality of powers including a first power, a second power smaller than the first power, and a third power smaller than the second power at a predetermined timing. And
The write-once multi-layer light according to claim 21, wherein a value obtained by dividing the first power by the second power in each of the plurality of recording layers is recorded in advance in the specific recording layer. recoding media. When the mark is formed, the laser light is first set to the first power, then the second power after the time Ttop has elapsed, and then the first power again after the time Tm has elapsed. A fourth power smaller than the third power after Tlp elapses, and then the third power after time Tlc elapses,
The write-once type multilayer optical recording medium according to claim 21 or 22, wherein the time Ttop, the time Tm, and the time Tlp in each of the plurality of recording layers are recorded in advance in the specific recording layer. .   The specific recording layer is a recording layer disposed at a position closest to the laser light incident surface among the plurality of recording layers, and a position farthest from the laser light incident surface among the plurality of recording layers. The write-once type multilayer optical recording medium according to any one of claims 21 to 23, wherein the recording layer is any one of the recording layers disposed on the recording medium.   The write-once type multilayer optical recording medium according to any one of claims 21 to 24, wherein each of the plurality of recording layers is a recording layer made of an inorganic material. A program used in an information recording apparatus capable of recording information on a write once multi-layer optical recording medium having a plurality of recording layers,
When recording is performed on a recording layer other than the specific recording layer which is the recording layer on which user data is first recorded among the plurality of recording layers, optimum recording power and recording are performed in the specific recording layer. The optimum recording power in the target recording layer from the known optimum recording power in the specific recording layer using known coefficient information indicating the relationship with the optimum recording power in the target recording layer that is a recording layer. A procedure for calculating
A program for causing a control computer of the information recording apparatus to execute a procedure for performing recording on the target recording layer using an optimal recording power in the target recording layer.   A computer-readable recording medium on which the program of claim 26 is recorded. An information recording apparatus capable of recording information on a write once multi-layer optical recording medium having a plurality of recording layers,
An optical pickup device;
When recording is performed on a recording layer other than the specific recording layer which is the recording layer on which user data is first recorded among the plurality of recording layers, optimum recording power and recording are performed in the specific recording layer. The optimum recording power in the target recording layer from the known optimum recording power in the specific recording layer using known coefficient information indicating the relationship with the optimum recording power in the target recording layer that is a recording layer. An information recording device comprising: a processing device that calculates An information recording system capable of recording information on a write once multi-layer optical recording medium having a plurality of recording layers,
An information recording apparatus according to claim 28;
A control device for controlling the information recording device.

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