JP2010067344A - Optical recording medium, information recording method, and information reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize a recording condition for a multi-layer recordable optical disc relatively quickly. <P>SOLUTION: For example, a single-sided dual-layer recordable disc (100) is used. Information recording is performed by forming mark and space portions in a data area (DA) thereof by using laser with modulated emission power. Here, Pp denotes maximum laser power (peak power) for forming the mark portion, and Pb denotes bias power for forming the space portion. A power ratio Pb/Pp of Pb to Pp is calculated for each of recording layers (L0, L1) (ST16). Information is recorded on any (L0 and/or L1) of the recording layers based on the result of calculation (ST14-ST22). In this method, the calculated power ratio Pb/Pp varies among the recording layers. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical disc (information recording medium using light in a broad sense) capable of recording and reproducing information from one side of a disc with respect to two or more recording layers, a recording method thereof, and a reproducing method thereof.

  There are roughly three types of optical disks: a read-only ROM disk, a write-once R disk, a rewritable RW or a RAM disk. With the increase in information capacity, there is a demand for further increase in the capacity of optical disks. In order to increase the capacity of the optical disk, a method of increasing the recording density by narrowing the beam spot by shortening the laser wavelength or increasing the numerical aperture NA, or a multilayer structure in which a plurality of recording layers are provided on one side of the disk (Patent Document 1).

  Of these, optical discs having a multilayer structure are mainly read-only dual-layer ROM discs, but recently, write-once dual-layer discs (DVD-R: DL) using a laser wavelength of 650 nm are also available. It has been commercialized. In a method for recording and reproducing an optical disk using an organic dye material in a recording layer such as a DVD-R, a recording mark that causes a change in the reflectance of the dye is formed by modulating the power of the laser beam, and the recording mark and the recording mark are not recorded. Information recording is performed using the reflectance difference of the recording unit. The laser light power modulation method is performed by multi-pulse in DVD-R, for example (Patent Document 2).

JP 2004-206849 A (refer to paragraphs 0036 to 0041 and FIG. 1) JP-A-9-282660 (see abstract)

  When a recordable single-layer R disk capable of recording at a laser wavelength of 405 nm was created and information recording was examined, it was not so important when recording was performed at a conventional 650 nm laser wavelength. Bias power was found to be very important in controlling the mark length. However, the fact that this bias power also affects the recording characteristics further increases the parameters of the recording conditions, and it takes a lot of time to find the optimum recording conditions. Therefore, if the recording power is changed with the ratio of the recording power (or peak power of the recording pulse) and the bias power constant, the optimum recording conditions (for example, the recording wavelength and the recording waveform are determined in a short time) It was found that the condition for determining the recording power at which the error rate is minimized can be found.

  However, when a two-layer R disk was manufactured and information was recorded in the same manner, a problem occurred. That is, when recording was performed with the same ratio of recording power and bias power in each layer, even when both recording layers were made of the same recording layer material, the recording characteristics of one layer were very deteriorated.

  In addition, when an information recording medium (especially a multi-layer optical disk that performs high-density recording with a blue laser) is stored for a long period of time or in a severe environment such as high temperature and high humidity, the optimum recording power is There is also a problem that it takes a long time to find the optimum recording condition since it changes compared to immediately after manufacturing the recording medium.

  One object of the present invention is to enable optimization of recording conditions in a relatively short time in a multilayer recordable optical disc.

  A recording method according to an embodiment of the present invention uses a laser whose emission power is modulated in a data area (DA) of a multilayer optical disc (100) having a plurality of recording layers (L0, L1) and a mark portion. In this method, information is recorded by forming a space portion. Here, when the maximum laser power (or peak power) when forming the mark portion is Pp and the bias power when forming the space portion is Pb, the power ratio Pb / Pb to Pb Pp is calculated for each recording layer of the plurality of recording layers (L0, L1) (ST16), and information is recorded on one of the plurality of recording layers (L0 and / or L1) based on the calculation result (ST0). ST14 to ST22). In this method, the calculated power ratio Pb / Pp is different for each of the recording layers (different in ST16 because Pb / Pp of L0 and L1 are independently calculated).

  Finding the optimum conditions for recording on an optical disc having a plurality of recording layers (for example, conditions for determining the recording power at which the bit error rate is minimized when the recording wavelength and recording waveform are fixed) in a relatively short time. Is possible.

The figure explaining the structural example of the multilayer optical disk based on one embodiment of this invention. FIG. 2 is a diagram for explaining an example of a physical sector layout in the optical disc of FIG. 1. FIG. 2 is a diagram for explaining a configuration example of a lead-in area in the optical disc of FIG. The figure explaining the structural example of the control data zone of FIG. FIG. 5 is a diagram illustrating a configuration example of FIG. 4. The figure explaining an example of the physical format information of FIG. The figure explaining an example of data area arrangement | positioning in the physical format information of FIG. The figure explaining the structural example of a part of physical format information of FIG. 5 (L0 relation). The figure explaining the structural example of the other part (L1 relation) of the physical format information of FIG. The figure explaining the example of the waveform (write strategy) of a recording pulse. The flowchart figure explaining an example of the recording method concerning one embodiment of this invention. The flowchart figure explaining an example of the reproducing | regenerating method which concerns on one embodiment of this invention. The figure explaining the example when the power ratio with respect to L0 layer differs from the power ratio with respect to L1 layer in the recording using a single-sided double layer optical disk.

  Hereinafter, various embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a configuration example of a multilayer optical disc (for example, a write once single-sided dual layer optical disc) 100 according to an embodiment of the present invention. As illustrated in FIGS. 1A and 1B, the optical disc 100 includes a transparent resin substrate 101 formed in a disc shape from a synthetic resin material such as polycarbonate (PC). In the transparent resin substrate 101, grooves (grooves) are formed concentrically or spirally. The transparent resin substrate 101 can be manufactured by injection molding using a stamper.

  Here, a first layer (L0) organic dye recording layer 105 and a light transflective layer 106 are laminated in order on a 0.59 mm thick transparent resin substrate 101 such as polycarbonate, and a photopolymer (2P resin) is formed thereon. 104 is spin coated. Then, the shape of the groove (groove) of the second layer (L1) is transferred thereon, and a second layer organic dye recording layer 107 and a reflective film 108 such as silver or silver alloy are sequentially laminated. Another transparent resin substrate (or dummy substrate) 102 having a thickness of 0.59 mm is bonded to the laminate of the L0 and L1 recording layers via the UV curable resin (adhesive layer) 103. The organic dye recording films (recording layers 105 and 107) have a two-layer structure sandwiching the transflective layer 106 and the intermediate layer 104. The total thickness of the bonded optical disc thus completed is approximately 1.2 mm.

  Here, on the transparent resin substrate 101, for example, spiral grooves having a track pitch of 0.4 μm and a depth of 60 nm are formed (in the respective layers L0 and L1). This groove is wobbled, and address information is recorded on this wobble. Then, recording layers 105 and 107 containing an organic dye are formed on the transparent resin substrate 101 so as to fill the groove.

  As the organic dye forming the recording layers 105 and 107, an organic dye whose maximum absorption wavelength region is shifted to a longer wavelength side than the recording wavelength (for example, 405 nm) is used. Further, the absorption is not extinguished in the recording wavelength region (for example, 450 nm to 600 nm), and it is designed to have a considerable light absorption in the long wavelength region.

  The organic dye is dissolved in a solvent to form a liquid and can be easily applied to the transparent resin substrate surface by a spin coating method. In this case, the film thickness can be managed with high accuracy by controlling the dilution rate with the solvent and the number of rotations during spin coating.

  Examples of organic dyes used in one embodiment of the present invention include cyanine dyes, styryl dyes, and azo dyes. In particular, cyanine dyes and styryl dyes are suitable because the absorptance with respect to the recording wavelength can be easily controlled. The azo dye may be used alone or as a complex of one molecule of azo compound or more and a metal.

  The azo metal complex used in one embodiment of the present invention uses cobalt, nickel, or copper as the central metal M to enhance light stability. However, not limited thereto, scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver, Gold, zinc, cadmium, mercury, or the like may be used as the central metal M of the azo metal complex.

  In addition, when the track before information recording is focused or tracked by the recording laser beam, the light reflectance is low. Thereafter, the decomposition reaction of the dye is caused by the laser light, and the light absorptance is lowered, so that the light reflectance of the recording mark portion is increased. Therefore, a so-called Low-to-High (or L to H) characteristic is realized in which the light reflectance of the recording mark portion formed by irradiating the laser light is higher than the light reflectance before the laser light irradiation. is doing.

  Note that the heat generated by the recording laser irradiation may cause deformation of the transparent resin substrate 101, particularly the groove bottom (L0 or L1). In this case, a phase difference may occur in the laser reflected light during reproduction after recording (compared to the case without thermal deformation).

  In one embodiment of the present invention, examples of physical formats applied to the L0 layer and the L1 layer existing on the transparent resin substrate 101 and the photopolymer (2P resin) 104 include the following. That is, the general parameters of a write once single-sided dual layer disc are almost the same as the general parameters of a single layer disc, but differ in the following points. The user can use a recording capacity of 30 GB, the inner radius of the data area is 24.6 mm in the layer 0 (L0 layer), 24.7 mm in the layer 1 (L1 layer), and the outer radius of the data area is 58.1 mm (common to layer 0 and layer 1).

  In the optical disc 100 of FIG. 1A, the system lead-in area SLA includes a control data section as illustrated in FIG. 1C, and this control data section is recorded as a part of physical format information or the like. Parameters relating to recording such as power (peak power) and bias power are included for each of L0 and L1.

  Further, mark / space recording is performed on the tracks in the data area DA of the optical disc 100 by a laser having a predetermined recording power (peak power) and bias power as illustrated in FIG. By this mark / space recording, as illustrated in FIG. 1E, for example, object data (VOB, etc.) such as a high-definition TV broadcast program and its management information (VMG) are stored in the data area DA (L0 and (Or L1).

《Information area format》
FIG. 2 is a diagram for explaining an example of a physical sector layout in the optical disc 100 of FIG. As illustrated in FIG. 2, the information area provided across the two layers includes seven areas: a system lead-in area, a connection area, a data lead-in area, a data area, a data lead-out area, a system lead-out area, It consists of a middle area. By providing a middle region in each layer, the reproduction beam can be moved from layer 0 (L0) to layer 1 (L1). The data area DA records main data (management information VMG, object data VOB, etc. in the example of FIG. 1E). The system lead-in area SLA includes control data, a reference code, and the like. The data lead-out area enables continuous and smooth reading.

《Leadout area》
The system lead-in area and the system lead-out area include tracks composed of embossed pits. The layer 0 (L0) data lead-in area, data area, and middle area, and the layer 1 (L1) middle area, data area, and data lead-out area include groove tracks. The groove track is continuous from the start position of the data lead-in area of layer 0 to the end position of the middle area, and is continuous from the start position of the middle area of layer 1 to the end position of the data lead-out area. When a pair of single-sided dual-layer disc substrates are prepared and bonded together, a double-sided, four-layer disc having two readout surfaces is obtained.

  FIG. 3 is a diagram for explaining a configuration example of the lead-in area in the optical disc of FIG. As illustrated in FIG. 3, the system lead-in area SLA of layer 0 (L0) includes an initial zone, a buffer zone, a control (control) data zone, and a buffer zone in order from the inner periphery side. Layer 0 data lead-in area is blank zone, guard track zone, drive test zone, disk test zone, blank zone, RMD (Recording Management Data) duplication zone, L-RMZ (recording position management data) in order from the inner circumference side , R physical format information zone, and reference code zone. The start address (inner circumference side) of the data area of layer 0 (L0) and the end address (inner circumference side) of the data area of layer 1 are shifted by the clearance, and the end of the data area of layer 1 (L1) The address (inner circumference side) is on the outer circumference side from the start address (inner circumference side) of the data area of layer 0.

《Lead-in area structure》
FIG. 3 illustrates the structure of the lead-in area of layer 0 (L0). In the system lead-in area, an initial zone, a buffer zone, a control data zone, and a buffer zone are arranged in order from the inner circumference side. The data lead-in area includes a blank zone, a guard track zone, a drive test zone, a disc test zone, a blank zone, an RMD duplication zone, and a recording position management (recording management) zone (L- RMZ), R physical format information zone, and reference code zone.

<Details of system lead-in area>
The initial zone includes embossed data segments. The main data of the data frame recorded as the data segment of the initial zone is set to “00h”. The buffer zone is composed of 1024 physical sectors from 32 data segments. The main data of the data frame recorded as the data segment of this zone is set to “00h”. The control data zone includes embossed data segments. The data segment includes embossed control data. The control data is composed of 192 data segments starting from PSN 123904 (01 E400h).

  A configuration example of the control data zone is shown in FIG. FIG. 5 shows a configuration example of the data segment in the control data section. The content of the first data segment of the control data section is repeated 16 times. The first physical sector of each data segment includes physical format information. The second physical sector of each data segment contains disk manufacturing information. The third physical sector of each data segment contains copyright protection information. The contents of the other physical sectors of each data segment are reserved for system use.

  FIG. 6 is a diagram for explaining an example of physical format information in the control data section of FIG. 5, and FIG. 7 is a diagram for explaining an example of data area arrangement in this physical format information. The description contents of each byte position (BP) of the physical format information are as follows. The values of read power, recording speed, data area reflectivity, push-pull signal, and on-track signal shown in BP132 to BP154 are examples. These actual values can be selected by the disc manufacturer from values satisfying the specifications of emboss information and the characteristics of user data characteristics after recording. The contents of the data area arrangement described in BP4 to BP15 are as shown in FIG. 7, for example.

BP149 and BP152 in FIG. 6 specify the reflectance of the data areas of layer 0 and layer 1. For example, 0000 1010b indicates 5%. The actual reflectivity is specified by the following formula:
Actual reflectance = value × (1/2).

The BP 150 and the BP 153 specify the push-pull signal of the layer 0 and the layer 1. In each of these BPs, a bit b7 (not shown) designates the track shape of the disk of each layer, and bits b6 to b0 (not shown) designate the amplitude of the push-pull signal:
Track shape: 0b (track on the groove)
1b (track on land)
Push-pull signal: For example, 010 1000b indicates 0.40.

The actual amplitude of the push-pull signal is specified by the following formula:
Actual amplitude of push-pull signal = value × (1/100).

BP151 and BP154 specify the amplitude of the on-track signal of layer 0 and layer 1:
On-track signal: For example, 0100 0110b indicates 0.70.

The actual amplitude of the on-track signal is specified by the following formula:
Actual amplitude of on-track signal = value x (1/100)
In addition, in the physical format information BP512 to BP543, the recording related parameters of L0 as illustrated in FIG. 8 can be described, and information such as the initial peak power and bias power when recording the L0 layer is as follows. It can be taken from the description of FIG. Further, the physical format information BP544 to BP2047 can describe the recording related parameters of L1 as exemplified in FIG. 9, and information such as the initial peak power and bias power when recording the L1 layer is as follows. It can be taken from the description of FIG.

  The evaluation disk of the write-once type dual-layer optical disk 100 according to one embodiment of the present invention can be manufactured as follows. That is, the L0 recording layer 105 is formed on the transparent resin substrate 101 by applying a 1.2 wt% TFP solution of an organic dye by spin coating. The thickness of the dye after coating from the groove bottom is 60 nm. A reflective film 106 made of Ag alloy is deposited on the dye-coated substrate by 25 nm by sputtering, and an intermediate layer 104 of 2P (photo polymer) resin is spin-coated to a thickness of 25 μm. Here, a separately prepared polycarbonate stamper is bonded to transfer the groove shape, and then the stamper is peeled off. An L1 recording layer 107 is formed by applying a 1.2 wt% TFP solution of an organic dye on the intermediate layer 104 of the 2P resin thus formed by spin coating. On top of this, a reflective film 108 made of Ag alloy is laminated to a thickness of 100 nm by sputtering. On top of that, a transparent resin substrate 102 having a thickness of 0.59 mm is bonded using a UV curable resin 103.

  Using the information recording medium (single-sided, double-layered R evaluation disk) produced as described above, an experiment for evaluating a reproduction signal was performed. The apparatus used for the evaluation is an optical disk evaluation apparatus ODU-1000 manufactured by Pulstec Co., Ltd. The laser wavelength of this apparatus is 405 nm and NA is 0.65. The linear velocity during recording and reproduction was set to 6.61 m / s. The recording signal is 8-12 modulated random data, and information is recorded using a laser waveform including a constant recording power (peak power) and two types of bias powers 1 and 2 as shown in FIG. It was. The recording conditions at that time will be described below.

Explanation of Recording Conditions (Write Strategy Information) A recording waveform (exposure conditions at the time of recording) used when investigating the optimum recording power will be described with reference to FIG. There are four exposure levels, recording power (peak power), bias power 1 (Bias power 1), bias power 2 (Bias power 2), and bias power 3 (Bias power 3). When a long recording mark 9 (4T or more) is formed, modulation is performed in the form of a multipulse between recording power (peak power) and bias power 3 (Bias power 3). In this embodiment, the minimum mark length with respect to the channel bit length T is 2T in both the “H format” and the “B format”. When recording this 2T minimum mark, as shown in FIG. 10, one write pulse at a recording power (peak power) level is used after bias power 1 (Bias power 1), Immediately after the write pulse, the bias power is 2 (Bias power 2). When recording a recording mark 9 having a length of 3T, two write pulses of the first pulse and the last pulse of the recording power (peak power) level that come after the bias power 1 (Bias power 1) are exposed. After that, the bias power 2 is once set. In the case of recording a recording mark 9 having a length of 4T or more, the bias power 2 (Bias power 2) is obtained after exposure with the multi-pulse and the last pulse.

A vertical broken line in FIG. 10 indicates a channel clock period (T). Rises from a position delayed T _SFP from a clock edge when recording the minimum mark of 2T, it falls at the position of T _ELP from behind the edge of one clock later. The period in which the bias power 2 (Bias power 2) immediately following is defined as _{T LC.} The value of T _SFP and _{T ELP} and _{T LC} are in the case of the H format is recorded in the physical format information PFI in the control data zone CDZ.

In the case of forming a long recording mark of 3T or more, the signal rises from a position delayed by _SFP from the clock edge, and ends with the last pulse. Immediately after the last pulse, the duration bias power 2 of _{T LC} (Bias power 2), but defines a deviation time from the rising / falling timing of the clock edge of the last pulse _{T SLP,} with _{T ELP.} Further, the time measured from the clock edge of the leading edge falling timing is defined as _TEFP , and the interval between one multipulse is defined as _TMP .

Each interval of _{T ELP -T SFP, T MP,} T ELP -T SLP, T LC is defined by a half value width with respect to the maximum value. In this embodiment, the parameter setting range is 0.25T ≦ T _SFP ≦ 1.50T (eq.01)
0.00T ≦ T _ELP ≦ 1.00T (eq.02)
1.00T ≦ T _EFP ≦ 1.75T (eq.03)
−0.10T ≦ T _SLP ≦ 1.00T (eq.04)
0.00T ≦ T _LC ≦ 1.00T (eq.05)
0.15T ≦ T _MP ≦ 0.75T (eq.06)
And

  Furthermore, in this embodiment, the value of each parameter can be changed according to the length of the recording mark (Mark length) and the space length (Leading / Trailing space length) immediately before / after.

  When the optimum recording power of the write-once information recording medium recorded by the recording principle shown in this embodiment is examined, the parameters are bias power 1 (Bias power 1), bias power 2 (Bias power 2), The values of bias power 3 are 2.6 mW, 1.7 mW, and 1.7 mW, respectively, and the reproduction power is 0.4 mW.

  Based on the parameter values calculated as described above, "Optimum recording conditions for the storage medium (write strategy information) on the device (drive) that performed trial writing in the drive test zone" Can be determined.

  FIG. 11 is a flowchart for explaining an example of the recording method according to the embodiment of the invention. With reference to this flowchart, an example of a procedure for determining optimum recording conditions in the two-layer optical disc 100 according to one embodiment of the present invention will be described. First, parameters related to recording (see FIGS. 6 to 9) are read from data described in the system lead-in area SLA (ST10).

  In order to shorten the time for determining the recording condition as much as possible, first, according to the read parameters (for example, in the test recording of the L0 layer, the value of the peak power (Pp) and the value of the bias power 1 (Pb) in FIG. 8 are used. In the test recording of the L1 layer, test recording is performed (using the peak power value and the bias power 1 value in FIG. 9) (ST12). When the bit error rate (SbER) of the reproduction signal from the place where such test recording has been performed is measured and the SbER of the measurement result is worse than a predetermined threshold value (for example, 5.0e-5) (NG of ST14), Pp / Pb is calculated from the parameters described in the data read from the system lead-in (ST16), the recording power is changed while keeping Pp / Pb constant (ST18), and a new test recording is performed with the changed recording power. (ST12), SbER measurement is repeated again (processing loop of ST12 to ST18), and the optimum recording condition is searched.

  When the measurement result SbER is better than a predetermined threshold value (for example, 5.0e-5) (OK in ST14), the recording condition at that time is determined to be the optimum recording condition as it is, and the recording target subjected to the test Data recording is started on the layer (L0 and / or L1) (ST20). This data recording is continued under the optimum recording conditions determined in ST20 (ST22, ST24N).

  Here, SbER was used to determine whether or not the test recording conditions were good, but this could be an index that can determine whether the data error rate, signal-to-noise ratio related information (such as PRSNR), or recording quality is good or bad. Any one can be used.

  In this embodiment, the physical format information of the system lead-in (and / or lead-out) described in the information recording medium is first read and test recording is performed with the set value. However, the present invention is not limited to this. However, for example, Pp / Pb may be set to a default constant value from the beginning to perform test recording, and thereafter, a process (optimization process) for searching for optimum recording conditions by appropriately changing the recording power may be performed.

  In this embodiment, the used Pp / Pb parameter may be newly recorded on the information recording medium, and this value may be read and used when performing additional writing thereafter. By doing so, the time required for the optimization process can be shortened from the beginning.

  In this embodiment, the parameters already described in the information recording medium are read and used. However, the present invention is not limited to this, and each recorder (or disk drive) may be used. A list of Pp / Pb may be stored in advance as ROM data according to the type of the high disc.

  In this embodiment, the information read from the disk uses the data in the system lead-in area. However, the present invention is not limited to this. For example, data recorded in the wobble signal may be used. .

  FIG. 12 is a flowchart for explaining an example of the reproducing method according to the embodiment of the present invention. At the time of reproduction, management information (such as VMG in FIG. 1E) of the recorded content is read from a predetermined track of the optical disc 100 recorded under the optimal recording conditions by the processing of FIG. 11 (ST30). In accordance with the description contents, related object data (VOB or the like) is reproduced (ST32).

  As described with reference to FIG. 11, when recording information on a multi-layer optical disc, the ratio of recording power (peak power) and bias power is different in each layer, and the recording power and bias set in advance in each layer. Use the power ratio. By doing so, in a relatively short time, good recording conditions (for example, when the recording wavelength and recording waveform are determined for each layer, the error rate is below a predetermined threshold determined from the viewpoint of practicality and the like. Can be found. The reason for this is that the recording layer becomes multi-layered, so the aberration of the laser light in each layer and the thermal effect of the information recording medium, the distance from the laser to the recording layer (use the light that has passed through the other translucent recording layer) This is considered to be because the relationship between the bias power and the recording power is different due to the difference in whether or not to do so, so that separate optimization is required for each layer.

  FIG. 13 shows data supporting the above idea. In recording using the single-sided, dual-layer optical disc 100, a change curve of the power ratio [Pb / Pp] a versus the error rate SbER for the L0 layer and the power ratio for the L1 layer [ The change curve of Pb / Pp] b versus error rate SbER is illustrated to be different by at least ± 5% (about 20% in the illustrated example).

<Summary>
Information is recorded on a recordable information recording medium (additional recordable or rewritable optical disc) having at least two layers of recording layers sandwiching an intermediate layer and a substrate, and having concentric or spiral grooves on the substrate. In the recording method, when information is recorded on the information recording medium, the emission power of the laser is modulated, the highest power (peak power) when forming the recording mark portion is Pp, and the space portion is formed. A method may be used in which Pb / Pp varies depending on each recording layer (L0, L1, etc.) when the light emission power (bias power) is Pb.

  To make it possible to start recording information in a shorter time (that is, to minimize the waiting time from when the disk is loaded into the drive until it can actually start data recording) The read physical format information (including information such as recording power) is read out, and Pb / Pp to be used is determined from the information. At this time, Pb / Pp may be read from the optical disc as it is, or the recording power (peak power) and bias power may be read from the optical disc and calculated therefrom.

  The recordable multilayer optical disc according to an embodiment of the present invention includes at least a substrate and two or more recording layers sandwiching an intermediate layer, and concentric or spiral grooves on the substrate. Is provided. In this optical disc, information recording is performed by modulating the emission power of the laser, the highest power (peak power) when forming the recording mark portion is Pp, and the power (bias power) emitted when forming the space portion. When Pb is Pb, Pb / Pp is made different for each recording layer.

  In this optical disc, at least recording power and bias power in each layer at the time of recording are recorded, and a ratio of recording power (peak power) and bias power described for each layer is different. In this case, it is possible to obtain the optimum recording condition for each layer in a shorter time (as compared to the case where such information is not used) from the recording power and bias power information for each layer.

  The recording method according to one embodiment of the present invention is particularly effective for a write once type (recordable only once at the same location) optical disc. In the case of using a single-sided two-layer optical disc, the recording power on the second recording layer (L1) is larger than the bias power when recording on the first recording layer (L0) as viewed from the light incident side. It is better if the bias power is higher.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the gist of the present invention or a future implementation stage based on the technology available at that time. It is. For example, although the embodiment has been described centering on a two-layer R disk, the technical idea of obtaining optimum recording conditions with a different power ratio for each layer can be applied to a multilayer RW disk or a multilayer RAM.

  In addition, the embodiments may be appropriately combined as much as possible, and in that case, the combined effect can be obtained. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some configuration requirements are deleted from all the configuration requirements shown in the embodiment, a configuration from which these configuration requirements are deleted can be extracted as an invention.

DESCRIPTION OF SYMBOLS 100 ... Multi-layer (2 layers or more on one side) optical disk; 101 ... Polycarbonate substrate on the L0 layer side; 102 ... Polycarbonate substrate on the L1 layer side (dummy substrate); 103 ... UV curable resin (adhesive layer); ... L0 recording layer; 106 ... L0 reflective layer (semi-transmissive to laser light); 107 ... L1 recording layer; 108 ... L1 reflective layer (semi-transmissive to laser light if 3 layers on one side; Full reflection of laser light).

Claims (4)

In a disc-shaped optical recording medium having a recording layer capable of recording / reproducing information by light of a predetermined wavelength,
Information recorded on the optical recording medium using the difference in reflectance between the recorded mark and the unrecorded part is reproduced,
The optical recording medium uses light peak power and bias power,
An optical recording medium on which information corresponding to a ratio between the bias power and the peak power is recorded by a wobble signal.   An information recording method for recording information on the recording layer of the recording medium using the optical recording medium according to claim 1.   An information reproducing method for reproducing information from the recording layer of the recording medium using the optical recording medium according to claim 1.   The optical recording medium according to claim 1, wherein information describing a polarity of the recording mark is recorded on the optical recording medium.

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