JP2005122896A - Method of generating index, method of adjusting recording condition of information recording medium, and information recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of generating an index, a method of adjusting recording condition of an information recording medium, and an information recording device which enable information to be properly recorded irrespective of recording speed without the information recording device's erroneous learning of an optimum recording power when information is recorded into a medium corresponding to high speed recording. <P>SOLUTION: An 11T single signal and a 3T single signal are recorded on a DVD-RW at the optimum recording power P1 and a recording power P2 of an intensity of 85% with relative to the optimum recording power P1, and then these signals are reproduced to calculate asymmetry values A1 and A2. If a difference (A1-A2) between both asymmetry values is equal to or greater than a reference value of 0.05, it is judged that a method using the asymmetry values is available for the OPC, and if the difference is less than a reference value of 0.05, it is judged that the method is not available. Then, the judgement result is recorded on the DVD-RW as an index. A DVD drive judges whether the asymmetry value is used for the OPC or not on the basis of the index. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for generating an index to be recorded on an optical information recording medium such as a DVD-RW (Digital Versatile Disk ReWritable), a recording condition adjusting method for an information recording medium, and an information recording apparatus, and in particular, a recording speed can be selected. The present invention relates to an index generation method for an information recording medium, a recording condition adjustment method for an information recording medium, and an information recording apparatus.

  Recently, recordable optical discs such as DVD-R, DVD-RW, and DVD + RW have been developed, and some of them are put on the market together with information recording devices (drives) for recording and reproducing information on the optical disc. ing. When recording information on an optical disk, these information recording apparatuses check whether the power of laser light for recording (hereinafter referred to as recording power) is an appropriate value. This is an operation generally called OPC (Optimum Power Control), which is extremely important for a recording type optical disc.

  An optical head is mounted on the optical information recording apparatus, the optical head emits laser light, and this laser light is irradiated onto the recording surface of the optical disk. At this time, the recording power of the laser light applied to the optical disk varies depending on various causes. For this reason, even though the optical information recording apparatus intends to emit laser light of a predetermined power to the optical head, the power of the laser light actually irradiated to the optical disk is often out of the proper range. Therefore, the OPC function is to calibrate the recording power based on the information obtained from the actually recorded signal.

  As an OPC method, a β method using a β value correlated with an asymmetry value and a γ method using a γ value correlated with a signal amplitude of a reproduction signal are known (for example, non-patent). See references 1 and 2.)

  First, the β method will be described. FIG. 9 is a graph illustrating the definition of the asymmetry value with time on the horizontal axis and signal output on the vertical axis. FIG. 10 takes time on the horizontal axis and DC (direct current) on the vertical axis. FIG. 11 is a graph for explaining the definition of the β value by taking the output of the signal from which the component is removed. FIG. 11 is a graph showing the recording power on the horizontal axis and the asymmetry value and the jitter value on the vertical axis. It is a graph which shows the correlation of a power, an asymmetry value, and a jitter.

  On the optical disk, a relatively long cycle signal, for example, a long mark (amorphous region) having a length 11 times (11T) of the channel clock cycle T and a long space (crystal region) having a length of 11T are alternately arranged. After recording a repeated 11T single signal, a relatively short period signal, for example, a 3T single signal consisting of a short mark having a length of 3T and a short space having a length of 3T is recorded, and these signals are recorded. When reproduced, an output waveform as shown in FIG. 9 is measured. The value of the output signal corresponding to the long space is V1, the value of the output signal corresponding to the long mark is V2, the value of the output signal corresponding to the short space is V3, and the output signal corresponding to the short mark Is set to V4. At this time, the value of V1 is larger than the value of V3, and the value of V2 is smaller than the value of V4. This is because when the laser beam for reproduction is irradiated, the long space becomes brighter than the short space, and the long mark becomes darker than the short mark. The asymmetry value A is defined by the following mathematical formula 1. As shown in the following mathematical formula 1, the asymmetry value A is a value obtained by standardizing the difference between the center of the amplitude of the long period signal (11T single signal) and the center of the amplitude of the short period signal (3T single signal).

  Further, the β value is an asymmetry value that is simply calculated based on a signal obtained by removing a DC (direct current) component from the output signal described above, and its essence is the same as the asymmetry value defined by the equation 1. . The β value can be determined by the following procedure. That is, in the optical information recording apparatus (drive), the DC component is removed from the output signal shown in FIG. 9 to obtain an AC signal. The output waveform of this AC signal is as shown in FIG. At this time, if the value of the output signal corresponding to the long space in the AC signal is V5 and the value of the output signal corresponding to the long mark is V6, the β value is defined as shown in Equation 2 below.

  Note that the average level of the output signal shown in FIG. 9 is adopted as the zero level of the AC signal shown in FIG. 10, but since the actual output signal contains many short-cycle components, the zero level of the AC signal is shown. Is substantially equal to the center of the amplitude of the short period signal. Therefore, as shown in Formula 2, only the output signal values V5 and V6 of the long-period signal are used for the calculation of the β value, but the information of the short-period signal is included in the value of 0 level. The β value can be used as an asymmetry value. In an actual optical information recording apparatus, in order to easily amplify a signal by an amplifier, a signal from which a DC component has been removed is often handled. Further, the calculation of Formula 1 is the same as the calculation of Formula 2. Since the comparison takes time, an optical information recording apparatus often uses a β value as an asymmetry value.

  As shown in FIG. 11, the asymmetry value (β value) has recording power dependency, and the higher the recording power, the larger the asymmetry value. Hereinafter, the reason will be described. The larger the recording power, the larger the mark (amorphous part) formed on the optical disk, and the darker the mark, the lower the corresponding output signal. However, the shorter the mark, the more marked the decrease in the output signal. Become. Therefore, as the recording power increases, the output signal of the short mark greatly decreases, while the output signal of the long mark does not decrease so much. For this reason, as the recording power increases, the difference between the output signal of the relatively short mark and the output signal of the relatively long mark increases, and the asymmetry value increases.

  The β method is a method for adjusting the recording power by utilizing the fact that the asymmetry value has the recording power dependency. That is, as shown in FIG. 11, the jitter value depends on the recording power, and there is a recording power that minimizes the jitter value, that is, an optimum power (optimum laser power) P1. However, since the jitter value is a statistical quantity, it is difficult to measure in a short time. For this reason, the asymmetry value A1 at the recording power P1 at which the jitter is minimized is measured in advance and set as the target asymmetry value. When recording, the recording power is adjusted by searching the recording power so as to obtain the asymmetry value A1 of the target. Thus, in order to perform OPC using an asymmetry value (β value) by the β method, it is necessary for the asymmetry value to have some recording power dependency from the principle.

  Next, the γ method will be briefly described. The γ method is optimized by differentiating the signal amplitude of the reproduction signal with the recording power, obtaining the γ value normalized by the magnitude of the signal amplitude, and multiplying the recording power at which the γ value becomes 1.5 by 1.22. It is a method of seeking power.

  In general, the β method that monitors the relationship between long marks and short marks is more reliable than the γ method that monitors only the signal amplitude. Further, the coefficients 1.5 and 1.22 in the γ method described above are merely recommended values, and different values may be desirable depending on the optical head and the medium. For this reason, the γ method is generally a method that is difficult to use, and is not a preferred method.

DVD-R standard "DVD Specifications for Recordable Disc for General (DVD-R for General) Part 1 PHYSICAL SPECIFICATIONS Version 2.0" DVD-RW standard "DVD Specifications for Re-recordable Disc (DVD-RW) Part 1 PHYSICAL SPECIFICATIONS Version 1.1"

  However, the conventional techniques described above have the following problems. Recently, DVD-RW and DVD + RW using a phase change recording film are compatible with high-speed recording, and a medium with a wide corresponding recording speed (cover range), that is, recording only at a specific speed is not possible. In addition, media that can be recorded at a speed higher than the specific speed have appeared. Specifically, a medium capable of both recording at a specific speed (1x speed recording: 1x-speed Write Strategy) and recording at a speed twice this specific speed (2x speed recording: 2x-speed Write Strategy). Has appeared.

  However, the present inventors have found that in the case of a phase change recording film, the asymmetry value does not depend on the recording power when recording is performed at a relatively low speed on a medium that supports high-speed recording. The reason is presumed as follows. In order to enable high-speed recording in a phase-change medium, it is necessary to be able to erase recorded information by irradiating laser light for a shorter time than during low-speed recording. Therefore, it is necessary to make the phase change recording film easy to crystallize. However, as a result, when recording is performed by irradiating the phase change recording film with a relatively large recording power for a relatively long time during low-speed recording, the amorphous mark is recrystallized from its periphery due to residual heat. The mark becomes smaller. For this reason, even if the recording power is increased, the mark does not become very large, and the dependency of the signal level corresponding to the mark on the recording power is reduced. As a result, the recording power dependency of the asymmetry value is reduced.

  As described above, since the recording power dependency of the asymmetry value is reduced during low-speed recording, the β method cannot be used when the same medium is recorded at low speed even if the β method can be used during high-speed recording. This causes the following problems, for example. If a drive that supports only 1x recording is equipped with a recording power adjustment device that uses the β method as an OPC, and this drive is introduced to the world, there is a problem when using media that supports only 1x recording with that drive There is no. However, after that, for example, when a medium that supports from 1 × speed recording to 2 × speed recording appears, if the new medium is used in a drive that supports only the above 1 × speed recording, the drive can only record at 1 × speed. The β method, which cannot be used in double speed recording, is used as OPC to perform single speed recording. This means that the drive mistakenly learns the optimum recording power and cannot perform proper recording. Needless to say, this situation must be avoided.

  The present invention has been made in view of such problems, and when information is recorded on a medium compatible with high-speed recording, the information recording apparatus does not learn the optimum recording power, and the information is recorded regardless of the recording speed. It is an object of the present invention to provide an information recording medium index generation method, an information recording medium recording condition adjustment method, and an information recording apparatus.

  The index generation method according to the present invention measures the first asymmetry value in the first recording power by using the first recording power that minimizes the jitter, and the first recording power becomes 0.85. Whether the second asymmetry value is measured by using the second recording power P2 multiplied by the coefficient, and the asymmetry value can be used for OPC by using the first asymmetry value and the second asymmetry value. An index indicating whether or not is generated.

  Further, the index generation method creates an index indicating that the asymmetry value can be used for OPC when the difference between the first asymmetry value and the second asymmetry value is 0.05 or more. When the difference between the first asymmetry value and the second asymmetry value is less than 0.05, an index indicating that the asymmetry value cannot be used for OPC may be created.

  In the present invention, when the information recording apparatus adjusts the intensity of the recording light by recording the index on the information recording medium, the adjustment is performed in the correlation between the asymmetry value and the intensity of the recording light. It is possible to appropriately determine whether or not to do this. For this reason, this adjustment is performed when the intensity of the recording light cannot be adjusted based on the correlation between the asymmetry value and the intensity of the recording light, and the information recording apparatus erroneously learns the optimum recording power. Can be prevented. As a result, information can be properly recorded on the information recording medium regardless of the recording speed.

  According to the recording condition adjusting method for an information recording medium according to the present invention, asymmetry values obtained from a signal recorded on the information recording medium are compared with at least two asymmetry values under the recording conditions, and based on the comparison result. It is characterized in that a method for adjusting recording conditions is determined.

  An information recording apparatus according to the present invention is an information recording apparatus that records information by irradiating light onto an information recording medium, and records the information based on a correlation between an asymmetry value of the information recording medium and the intensity of light for recording. An adjustment unit for adjusting the intensity of light for recording, a signal recording unit for recording one signal with light of one intensity on the information recording medium and recording another signal with light of another intensity, The signal asymmetry value and the asymmetry value of other signals are measured to calculate a difference between them, and when the difference is equal to or greater than a reference value, the selection unit that activates the adjustment unit and the information recording medium are irradiated with light. And a recording unit for recording information.

  In the present invention, the signal recording unit records a predetermined signal on the information recording medium, and the selection unit measures the asymmetry value based on the predetermined signal, thereby adjusting the intensity of the recording light. Since the adjustment unit adjusts the intensity of the recording light based on this selection, information can be recorded in a good state even on an information recording medium on which no index is recorded.

  According to the present invention, an information indicating whether or not a method using an asymmetry value can be used as an OPC can be recorded on an information recording medium, so that the information recording apparatus can adjust recording conditions appropriately and stably. Therefore, the quality of the recording signal can be greatly improved. This effect is equivalent to significantly improving the reliability of the information recording medium and the information recording apparatus, and can greatly contribute to the development of the optical disc industry.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. First, a first embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a DVD-RW that is an information recording medium according to the present embodiment. The DVD-RW according to the present embodiment is a rewritable phase change recording type optical disc that supports from 1 × speed recording to 2 × speed recording.

As shown in FIG. 1, in the DVD-RW 1 according to the present embodiment, a disc-shaped transparent substrate 2 made of, for example, polycarbonate, having a thickness of, for example, 0.6 mm and a diameter of 12 cm is provided. Yes. A guide groove (not shown) called a pregroove is formed on the surface of the substrate 2 so that an information recording apparatus, that is, an optical head of a DVD drive can scan along the guide groove during recording and reproduction. It has become. On this substrate 2 reflective film 6 made of a dielectric film 5, AlTi made of a dielectric film 3, made of AgInSbTe phase change recording film 4, ZnS-SiO ₂ made of ZnS-SiO ₂ are laminated in this order . The dielectric films 3 and 5 are for protecting the phase change recording film 4 and controlling the interference condition of the laser beam to obtain a larger signal. The phase state of the phase change recording film 4 is in a crystalline state in the initial state, and information is recorded by being irradiated with a recording laser beam to be in an amorphous state. The reflective film 6 reflects the laser beam transmitted through the substrate 2, the dielectric film 3, the phase change recording film 4 and the dielectric film 5 toward the phase change recording film 4. A protective film made of an ultraviolet curable resin or the like may be provided on the reflective film 6.

  Further, LPP (Land Pre-Pit) shown in the DVD-RW standard is formed on the surface of the substrate 2 of the DVD-RW 1. The LPP is a pre-pit arranged on the side of the guide groove, and represents 0 or 1 bit depending on the arrangement method. The LPP constitutes a unit called a total 12-bit prepit data frame in which a 4-bit relative address and 8-bit information are added to each relative address, and 16 prepit data frames are grouped into a prepit block. Is configured. Conventionally, five types of pre-pit blocks are set according to the type of information included in the block. ID1 to Field. It was named ID5. In the DVD-RW 1 according to the present embodiment, this Field. ID1 to Field. In addition to ID5, as a sixth pre-pit block, Field. ID6 is set. And this Field. In the lower 4 bits of the pre-pit data frame, which is the twelfth relative address in ID6, an index indicating whether or not an asymmetry value is available (available for OPC) is recorded in the OPC when double-speed recording is performed. An index indicating whether or not an asymmetry value can be used is recorded in the upper 4 bits of the pre-pit data frame of the twelfth relative address in the OPC when performing 1 × speed recording. For example, when these indices are “0000b”, it indicates that an asymmetry value can be used as means for OPC, and when the index is “0001b”, it indicates that an asymmetry value cannot be used. The LPP also records information on the optimum recording power P1 of DVD-RW1 and the asymmetry value A1 (see FIG. 11) corresponding to the optimum recording power P1.

  Next, a method for setting this index will be described. As shown in FIG. 11, for DVD-RW, there is a certain correlation between the jitter value and the recording power, and there is a recording power P1 that minimizes the jitter value. This recording power P1 is the optimum recording power.

  First, two types of signals having different periods, such as an 11T single signal and a 3T single signal, are recorded on the DVD-RW1. At this time, as shown in FIG. 11, the signal is recorded by the recording power P1 having the minimum jitter value and the recording power P2 having a size of 85% of the recording power P1. When these signals are reproduced, an output waveform as shown in FIG. 10 is obtained. Next, an asymmetry value is calculated according to Equation 1 described above. As a result, as shown in FIG. 11, the asymmetry value A1 of the signal recorded with the recording power P1 and the asymmetry value A2 of the signal recorded with the recording power P2 are obtained. Next, the difference (A1-A2) between the asymmetry values A1 and A2 is obtained. Since the asymmetry value monotonically increases with respect to the recording power, the value of (A1-A2) becomes positive. Next, the value of (A1-A2) is compared with a reference value. The reference value is, for example, 0.05. If the value of (A1-A2) is equal to or greater than the reference value, the recording power dependency of the asymmetry value is sufficiently large, so it is determined that the asymmetry value can be used in OPC. Is recorded. On the other hand, if the value of (A1-A2) is less than the reference value, it is determined that it is impossible to use the asymmetry value in OPC because the recording power dependency of the asymmetry value is insufficient. Record “0001b” as an index.

  In the present embodiment, the 11T single signal and the 3T single signal are used as signals for measuring the asymmetry value, but the signal for measuring the asymmetry value is not necessarily limited to this. The long-cycle signal is not limited to the 11T single signal as long as it is a signal having a long cycle of about 11T single signal. However, for a short-cycle signal, a single signal having a length other than 3T can be used. However, since the 3T single signal changes most depending on the recording power, the recording power can be adjusted most effectively.

  Further, the DVD-RW 1 according to the present embodiment uses EFMplus as a modulation code. However, even when other codes such as 1-7 modulation are used, basically the same principle can be applied. These modulation codes limit the upper limit value and the lower limit value of the length of the mark to be formed.

  The reason why the intensity of the recording power P2 is 85% of the optimum recording power P1 and the reference value of the value of (A1-A2) is 0.05 will be described below. Three types of media (DVD-RW: medium 1 to medium 3) and three types of optical heads (optical head 1 to optical head 3) are prepared, and the above-described (A1-A2) is obtained by combining all media and optical heads. ) Value is measured. First, after performing OPC on these media by the β method, information is recorded and the results are evaluated. The evaluation results are shown in Table 1. As shown in Table 1, all three types of media have obtained good results by OPC using the β method in double speed recording, but good results have been obtained by OPC using β method in 1 × speed recording. It is not done. That is, the β method can be used as the OPC at the time of 2 × speed recording, but the β method cannot be used at the time of 1 × speed recording. This is equivalent to the fact that asymmetry values cannot be used for OPC.

  2A and 2B, the horizontal axis indicates the type of the medium (DVD-RW) and the vertical axis indicates the value of (A1-A2), and the recording power P2 is 90 of the optimum recording power P1. It is a graph which shows the value of (A1-A2) when it is set as the intensity | strength of%, (a) shows the measurement result at the time of 1 time speed recording, (b) shows the measurement result at the time of 2 time speed recording. 3A and 3B, the horizontal axis represents the type of the medium (DVD-RW) and the vertical axis represents the value of (A1-A2), so that the recording power P2 is the optimum recording power P1. It is a graph which shows the value of (A1-A2) when it is set as the intensity | strength of 85% of (a), (a) shows the measurement result at the time of 1 time recording, (b) shows the measurement result at the time of 2 times recording. . Further, Table 2 shows the value of (A1-A2) at the time of double speed recording when the recording power P2 is 80% of the optimum recording power P1.

  As shown in FIGS. 2A and 2B, when the value of the recording power P2 is 90% of the value of the optimum recording power P1, the value of (A1-A2) at the time of 1 × recording is 0 to About 0.03, and the value of (A1-A2) at the time of double speed recording is about 0.03 to 0.06. As described above, the value of (A1-A2) is generally larger at the time of double speed recording than at the time of single speed recording, but overlaps in the vicinity of 0.03. A clear reference value cannot be determined. Therefore, even if the value of (A1-A2) is calculated by setting the value of the recording power P2 to 90% of the value of the optimum recording power P1, a method using an asymmetry value as OPC based on this (A1-A2) value. It is difficult to uniquely determine whether or not it can be used.

  On the other hand, as shown in FIGS. 3A and 3B, when the value of the recording power P2 is 85% of the value of the optimum recording power P1, the value of (A1-A2) at the time of 1 × speed recording is It is about 0.003 to 0.04, and the value of (A1-A2) at the time of double speed recording is about 0.06 to 0.11. Thus, a clear difference is recognized between the (A1-A2) value at the time of 1 × speed recording and the (A1−A2) value at the time of 2 × speed recording, and if an appropriate reference value is set, (A1−A2). ) Based on the value, it can be uniquely determined whether or not the asymmetry value can be used as the OPC. Note that this reference value is an intermediate value between the maximum value (about 0.04) of 1 × speed recording data and the minimum value (about 0.06) of 2 × speed recording data in consideration of variations in measurement data. It is desirable to set it to 0.05. As a result, if the (A1-A2) value is 0.05 or more, the asymmetry value can be used as OPC, and if the (A1-A2) value is less than 0.05, the asymmetry value is not used as OPC. It can be determined that it is possible.

  Further, as shown in Table 2, when the value of the recording power P2 is 80% of the value of the optimum recording power P1, there is a case in which the (A1-A2) value cannot be measured during the double speed recording. To do. This is because if the recording power P2 is a value that is reduced by 20% from the optimum recording power P1, the recording power P2 becomes insufficient, the recording itself cannot be performed well, and the (A1-A2) value cannot be measured. It is. Therefore, even if the value of the recording power P2 is set to 80% of the value of the optimum recording power P1, and the value is calculated, a case where measurement cannot be performed occurs, and it is determined whether or not the asymmetry value can be used as OPC. I can't.

  Accordingly, when setting an index indicating whether or not an asymmetry value can be used as OPC, the intensity of the recording power P2 is set to 85% of the appropriate recording power P1, and the reference value of the value of (A1-A2) is set to 0.05. It is preferable that As is clear from the above description, the recording power P2 does not have to be strictly 85% of the recording power P1, but may be about 85%. Further, the reference value does not need to be strictly 0.05, and may be about 0.05.

  As described above, in this embodiment, the DVD drive adjusts the recording power because the index indicating whether or not the asymmetry value can be used as the OPC is recorded on the DVD-RW1 as the information recording medium at each recording speed. In this case, it can be accurately determined whether or not the asymmetry value should be used. For this reason, when the asymmetry value cannot be used, the asymmetry value is used, and it is possible to prevent the DVD drive from erroneously learning the optimum recording power. For this reason, information can be properly recorded on the DVD-RW 1 regardless of the recording speed.

  In the present embodiment, the asymmetry values A1 and A2 are measured by the optimum recording power P1 and the recording power P2 having an intensity of 85% of the optimum recording power P1, respectively, and the difference (A1−A2) between them is obtained. The index is set in comparison with 0.05 which is a reference value. Thereby, the said parameter | index can be set appropriately.

  As described above, according to the present embodiment, when a certain medium is completed, the above-described (A1-A2) value is measured at a desired recording speed for this medium, and this value is set to a reference value of 0. 0. If the comparison result is embedded in the medium as compared with 05, the drive can determine whether or not to operate the OPC using the asymmetry value by reading the information. Note that OPC using asymmetry values includes, for example, the β method described above and the multi β method described later. As a result, the DVD drive can perform the OPC operation without anxiety about future media changes.

  Next, a second embodiment of the present invention will be described. The present embodiment is a method for manufacturing the DVD-RW 1 according to the first embodiment configured as described above. The DVD-RW1 manufacturing method includes an index generation method. FIG. 4 is a flowchart showing a DVD-RW manufacturing method according to this embodiment and a recording method according to a fourth embodiment to be described later. Steps S1 to S3 show the DVD-RW manufacturing method according to this embodiment. Steps S4 and S5 show a DVD-RW recording method according to a fourth embodiment to be described later.

Hereinafter, a method for manufacturing the DVD-RW 1 will be described. As shown in step S1 of FIG. 4, first, a confirmation DVD-RW for confirming whether or not a method using an asymmetry value can be used as OPC is produced. As shown in FIG. 1, a disk-shaped transparent substrate 2 made of polycarbonate and having a thickness of, for example, 0.6 mm and a diameter of 12 cm is prepared. A pregroove (not shown) is formed on the surface of the substrate 2. Next, on the substrate 2 by sputtering, for example made of ZnS-SiO ₂ dielectric film 3, formed of a phase change recording film 4, ZnS-SiO ₂ formed of AgInSbTe dielectric film 5, made of AlTi reflecting film 6 are formed and laminated in this order. Then, if necessary, a protective film made of an ultraviolet curable resin or the like is formed on the reflective film 6. Thereby, it is confirmed whether or not an asymmetry value can be used as OPC, and a confirmation DVD-RW for generating the above-described index is produced based on the confirmation result.

  Next, as shown in step S2 of FIG. 4, using this confirmation DVD-RW, it is confirmed whether or not an asymmetry value can be used as OPC, and an index to be embedded is determined. First, for example, an 11T single signal and a 3T single signal are recorded on the confirmation DVD-RW by the optimum recording power P1 and the recording power P2 having an intensity of 85% of the recording power P1. Then, these signals are reproduced, and asymmetry values (β values) A1 and A2 corresponding to the recording powers P1 and P2 are calculated. When the (A1-A2) value is compared with the reference value 0.05 and the (A1-A2) value is equal to or greater than the reference value 0.05, an asymmetry value can be used as OPC at this recording speed. If the (A1-A2) value is less than the reference value 0.05, it is determined that the asymmetry value cannot be used as OPC. This determination result is expected to be the same when recording on the same type of medium at the same recording speed. For this reason, the above-described determination may be performed at least once for each recording speed on the confirmation DVD-RW.

  Next, as shown in step S3 of FIG. 4 and FIG. 1, a DVD-RW 1 in which the index is embedded is produced based on the determination result described above. Since LPP is an emboss signal embedded in the substrate when the substrate is manufactured, a substrate on which the index is recorded on the LPP may be formed as the substrate 2. That is, when the (A1-A2) value is equal to or greater than the reference value 0.05 and the asymmetry value can be used in OPC, “0000b” is used as an index, and Field. Recorded in the pre-pit data frame of the 12th relative address of ID6. On the other hand, when the (A1-A2) value is less than the reference value 0.05 and the asymmetry value cannot be used in the OPC, “0001b” is used as an index, and the Field. Recorded in the pre-pit data frame of the 12th relative address of ID6. In addition, information about the optimum recording power P1 and the asymmetry value A1 corresponding thereto is recorded in the LPP. Thereafter, the dielectric film 3, the phase change recording film 4, the dielectric film 5, and the reflective film 6 shown in FIG. 1 are formed in this order. These steps are the same as the steps for manufacturing the confirmation DVD-RW. Thus, the DVD-RW 1 according to the first embodiment described above is manufactured.

  In the present embodiment, as described above, the DVD-RW according to the first embodiment can be efficiently manufactured. In addition, since the index is recorded on the DVD-RW, the reliability when recording information is improved.

  Next, a third embodiment of the present invention will be described. This embodiment is an embodiment of an information recording apparatus that records information on the DVD-RW according to the first embodiment. This information recording apparatus is a DVD drive that records, reproduces, and erases information with respect to the DVD-RW1 that is the information recording medium according to the present embodiment. FIG. 5 is a block diagram showing the DVD drive of this embodiment. As shown in FIG. 5, the DVD drive 11 in the present embodiment is provided with a spindle drive device 12 that rotates the DVD-RW 1. In addition, the DVD-RW 1 is irradiated with laser light and the DVD-RW 1. An optical head 13 for detecting the laser beam reflected by the optical head 13 is provided.

  The optical head 13 is provided with a laser diode (LD) 14 that emits laser light. The laser light emitted from the LD 14 is condensed on the DVD-RW 1 and the laser light reflected by the DVD-RW 1. Is provided. In addition, a photodetector 16 that detects laser light from the DVD-RW 1 is provided. Further, in the optical path of the laser light emitted from the LD 14, the laser light emitted from the LD 14 is reflected toward the objective lens 15 and the laser light reflected by the DVD-RW 1 is transmitted toward the photodetector 16. A beam splitter 17 is provided.

  The DVD-R / RW standard is compatible with a DVD-ROM (DVD-Read Only Memory) and an optical head for recording with a low rim intensity in order to obtain large recording power. In order to confirm, a reproducing optical head in which the rim intensity is set high and the beam is narrowed is defined. Usually, a recording optical head is mounted on the DVD drive. On the other hand, the reproducing optical head is mounted on a test apparatus for confirming the quality of the signal recorded by the recording optical head.

  An RF circuit 18 is provided in a portion other than the optical head 13 in the DVD drive 11. The RF circuit 18 receives an output signal of the photodetector 16 and divides the output signal into data information and an LPP signal. Further, an EFM decoder 19 that receives the data information output from the RF circuit 18 and decodes the data information, and an LPP decoder 20 that decodes the LPP signal output from the RF circuit 18 are provided. The optical head 13, the RF circuit 18, and the LPP decoder 20 form a reading unit. Further, the output signal of the LPP decoder 20 is input, the index created based on the difference (A1-A2) in the asymmetry value is recognized, and it is determined whether or not the asymmetry value can be used when performing OPC. An A1-A2 information discriminator 21 is provided as a selection unit that selects a method to be executed.

  Furthermore, a system controller 22 is provided which receives the output signals of the LPP decoder 20 and the A1-A2 information discriminator 21 and controls the entire operation of the DVD drive 11. Furthermore, an output signal from the system controller 22 and the RF circuit 18 is input, and an OPC controller 23 that performs OPC when information is recorded on the DVD-RW 1 is provided. The OPC controller 23 is an adjustment unit that adjusts the recording power by performing the β method and the γ method as OPC, calculates the β value and the γ value, and obtains the learning result obtained by performing the β method and the γ method. Is fed back to the system controller 22.

  Furthermore, an EFM encoder 24 that is connected to the system controller 22 and encodes data information to be recorded on the DVD-RW 1 is provided. Furthermore, an LD driving circuit 25 that drives the LD 14 based on the output signal of the OPC controller 23 and the output signal of the EFM encoder 24 is provided. The EFM encoder 24 and the LD drive circuit 25 constitute a recording unit. Furthermore, a servo controller 26 that controls the position of the optical head 13 based on the output signal of the system controller 22 is provided.

  Next, a fourth embodiment of the present invention will be described. This embodiment is an information recording method for the DVD-RW 1 according to the first embodiment, that is, an operation of the DVD drive 11 according to the third embodiment. The information recording method according to the present embodiment includes a recording condition adjusting method. As shown in step S4 of FIG. 4 and FIG. 5, first, the recording conditions for the DVD-RW 1 are adjusted. That is, the system controller 22 of the DVD drive 11 operates the spindle drive device 12 to rotate the DVD-RW 1. Next, the system controller 22 drives the servo controller 26 to position the optical head 13 at a position where the index can be read from the DVD-RW 1. Then, the LD drive circuit 25 causes the LD 14 to emit laser light. This laser light is reflected by the beam splitter 17, converged by the objective lens 15, and condensed on the DVD-RW 1. Then, the laser light is reflected by the DVD-RW 1, collimated by the objective lens 15, passes through the beam splitter 17, and enters the photodetector 16.

  The photodetector 16 converts the incident laser light into an electrical signal and outputs it to the RF circuit 18. The RF circuit 18 divides this electrical signal into data information and an LPP signal, and outputs the data information to the EFM decoder 19 and outputs the LPP signal to the LPP decoder 20. At this time, data relating to the index is input to the LPP decoder 20. The LPP decoder 20 decodes the information contained in the LPP and outputs it to the system controller 22 and the A1-A2 information discriminator 21. At this time, data relating to the index is output to the A1-A2 information discriminator 21.

  The A1-A2 information discriminator 21 recognizes the index, and if the index is “0000b”, that is, indicates that the method using the asymmetry value can be used as the OPC, the β method is performed as the OPC. To the system controller 22. On the other hand, if the index is “0001b”, that is, indicates that the method using the asymmetry value cannot be used as OPC, the system controller 22 is instructed to perform the γ method as OPC.

  Based on this instruction, the system controller 22 issues a command to the OPC controller 23 to execute the β method or the γ method. When performing the β method, the OPC controller 23 issues a command to the LD drive circuit 25 to cause the LD 14 to emit laser light while changing the recording power, and to output a reproduction signal from the DVD-RW 1 to the photodetector. 16 and the RF circuit 18, and the β value is calculated by performing the calculation shown in Formula 2 above. Then, as shown in FIG. 11, the recording power is adjusted so that the β value becomes the β value A1 at which the jitter is minimized. Note that the β value A1 that minimizes the jitter is recorded in advance in the LPP of the DVD-RW. As a result, the recording power can be adjusted to the optimum recording power P1.

  After adjusting the recording conditions as described above, information is recorded on the DVD-RW 1 as shown in step S5 in FIG. Hereinafter, this recording operation will be described. With the spindle drive device 12 rotating the DVD-RW 1, the servo controller 26 controls the position of the optical head 13 to be positioned at a predetermined position on the DVD-RW 1. Then, information to be recorded in the system controller 22 is input. The system controller 22 outputs this information to the EFM encoder 24, and the EFM encoder 24 encodes this information with a modulation code such as EFMplus and outputs the information to the LD drive circuit 25. Based on the encoded signal, the LD drive circuit 25 drives the LD 14 of the optical head 13 and causes the LD 14 to emit laser light. The laser beam emitted from the LD 14 is applied to the DVD-RW 1 through the beam splitter 17 and the anti-reflective lens 15.

  At this time, as shown in FIG. 1, the laser light is incident from the substrate 2 side of the DVD-RW 1. Then, after passing through the substrate 2 and the dielectric film 3, the laser light reaches the phase change recording film 4, and a part of the phase change recording film 4 is heated to a temperature equal to or higher than the melting point to be melted. The laser light that has passed through the phase change recording film 4 passes through the dielectric film 5, is then reflected by the reflective film 6, passes through the dielectric film 5 again, and reaches the phase change recording film 4. Thereafter, the phase change recording film 4 is rapidly cooled, so that this portion becomes amorphous and a mark is formed. Thus, information is recorded by the phase change recording film 4 being locally in an amorphous state or a crystalline state.

  Next, a case where information recorded on the DVD-RW 1 is reproduced will be described. The LD 14 of the optical head 13 emits a laser beam with a constant output. At this time, the mark on the DVD-RW 1 has a low light reflectivity because the phase change recording film 4 is amorphous, and the intensity of the reflected light is low. On the other hand, since the phase change recording film 4 is in a crystalline state, the space between the marks has a higher light reflectivity than the mark and a higher intensity of reflected light. Reflected light whose intensity changes reflecting such recorded information is detected by the photodetector 16 and converted into an electrical signal. The RF circuit 18 divides this signal into data information and LPP signal, and outputs the data information to the EFM recorder 19. The EFM decoder 19 decodes the data information and outputs it to the system controller 22, and the system controller 22 outputs this data information to the outside. Thereby, the reproduction operation is performed.

  Next, a case where information recorded on the DVD-RW 1 is erased will be described. The LD 14 emits an erasing power laser beam lower than the recording power. As a result, the phase change recording film 4 of the DVD-RW 1 is heated to a temperature higher than the recrystallization temperature and lower than the melting point, and the amorphous portion is recrystallized. As a result, the recorded information is erased.

  In this embodiment, since the DVD drive 11 is provided with the A1-A2 information discriminator 21 for recognizing the index and selecting the OPC method, the DVD drive 11 is connected to the DVD-RW 1 in which the index is recorded. On the other hand, the recording power can be adjusted appropriately.

  In this embodiment, when the index indicates that a method using an asymmetry value as OPC cannot be used, the γ method is executed as OPC. Thus, even when the β method cannot be used, the recording power is not greatly deviated from the optimum recording power by adopting the γ method as the second best method.

  Next, a fifth embodiment of the present invention will be described. This embodiment is an embodiment of an information recording method for the information recording medium according to the first embodiment described above. Therefore, the DVD-RW and its manufacturing method in the present embodiment are the same as those in the first and second embodiments described above. In the DVD drive according to this embodiment, the default (priority) is that the OPC controller 23 (see FIG. 5) executes the multi-β method as OPC. The multi-β method uses an asymmetry value β3 calculated based on an 11T single signal and a 3T single signal and an asymmetry value β4 calculated based on an 11T single signal and a 4T single signal, and β3 is β4 This is a method for learning the optimum power by finding a recording power that is equal to, and was invented by the present inventors. This is based on the knowledge that the recording power in which β3 and β4 are equal to each other substantially matches the optimum recording power. Details of the multi-β method are described in the DVD-R / RW standard. Other configurations and operations of the DVD drive in the present embodiment are the same as those in the third and fourth embodiments described above. The effects of this embodiment are the same as those of the first to fourth embodiments described above.

  Next, a sixth embodiment of the present invention will be described. FIG. 6 is a block diagram showing a DVD drive according to this embodiment. In the present embodiment, an index indicating whether or not an asymmetry value can be used for a DVD-RW, that is, information indicating whether the above-mentioned (A1-A2) value is greater than or less than a reference value. Is not recorded. Other configurations of the DVD-RW in the present embodiment are the same as those in the first embodiment. On the other hand, the DVD drive is equipped with a function that allows the DVD drive itself to calculate the above-mentioned (A1-A2) value and check whether or not the asymmetry value can be used as the OPC before operating the OPC.

  As shown in FIG. 6, in the DVD drive 31 of the present embodiment, A1-A2 information is used instead of the A1-A2 information discriminator 21 as compared with the DVD drive 11 of the first embodiment shown in FIG. A checker 32 is provided. The A1-A2 information confirmation unit 32 is connected to the LPP decoder 20 and the system controller 22, confirms whether or not the above-mentioned index is recorded on the DVD-RW 34 to be recorded, and sends the result to the system controller 22. Are output. If the index is recorded, the index is recognized to determine whether the asymmetry value can be used in the same manner as the A1-A2 information discriminator 21 provided in the DVD drive 11 of the first embodiment. The method for executing the OPC is selected.

  In addition, the DVD drive 31 is provided with an A1-A2 information tester 33 connected to the system controller 22 and the LD drive circuit 25. When the A1-A2 information checker 32 determines that no index is recorded on the DVD-RW 34, the A1-A2 information checker 33 issues a command to the LD drive circuit 25 and measures the (A1-A2) value. To do. Other configurations of the DVD drive 31 of the present embodiment are the same as those of the DVD drive 11 of the first embodiment described above.

  Next, a recording condition adjusting method for the DVD drive 31 of the present embodiment configured as described above will be described. As shown in FIG. 6, first, the DVD drive 31 reads the index from the DVD-RW 34 by the same operation as in the first embodiment. At this time, in the first embodiment described above, the data related to the index is input to the A1-A2 information discriminator 21 (see FIG. 5), but in this embodiment, the data is input to the A1-A2 information checker 32. Is done.

  The A1-A2 information confirmation unit 32 confirms whether or not the index is recorded on the DVD-RW 34 and outputs the result to the system controller 22. Then, if an index is recorded on the DVD-RW 34, the A1-A2 information checker 32 recognizes this index, determines whether or not an asymmetry value can be used, and executes the OPC as a method for executing OPC. Select the γ method.

  When the index is not recorded on the DVD-RW 34, the system controller 22 operates the A1-A2 information tester 33, and information on the optimum recording power P1 recorded on the DVD-RW 34 and the asymmetry value A1 corresponding thereto. Is output to the A1-A2 information checker 33. Then, the A1-A2 information inspector 33 drives the LD drive circuit 25 based on the information on the optimum recording power, and the DVD- is recorded with the optimum recording power P1 and the recording power P2 corresponding to 85% of the recording power P1. A signal of a pattern that can measure an asymmetry value (β value) is recorded in the RW 34. The signal capable of measuring the asymmetry value is, for example, a signal composed of an 11T single signal and a 3T single signal as shown in FIG.

  Next, the OPC controller 23 measures the asymmetry value A1 in the recording power P1 and the asymmetry value A2 in the recording power P2. Then, the A1-A2 information checker 32 compares the value (A1-A2) with the reference value 0.05 based on the measurement result, and the value (A1-A2) is 0.05, which is the reference value. If this is the case, the system controller 22 is instructed to perform the β method as OPC. On the other hand, when the value of (A1-A2) is less than the reference value of 0.05, the system controller 22 is instructed to perform the γ method as OPC. Based on this instruction, the system controller 22 issues a command to the OPC controller 23 to execute the β method or the γ method. As a result, the recording power can be adjusted to the optimum recording power P1. Thereafter, information is recorded on the DVD-RW 34 in this recording power. The information recording method is the same as in the fourth embodiment. The recording method, reproducing method, and erasing method other than those described above in this embodiment are the same as those in the fourth embodiment described above.

  In the present embodiment, the DVD drive 31 checks whether or not the index is recorded on the DVD-RW 34 to be recorded. If the index is not recorded, the DVD drive itself has a value (A1-A2). Measure to determine if an asymmetry value is available. As a result, the OPC method can be accurately selected even for an information recording medium on which no index is recorded, and the OPC can be operated satisfactorily. As a result, even when a DVD-RW in which no index is recorded is used, there is no big problem that the optimum recording power is erroneously learned. The effects of the present embodiment other than those described above are the same as those of the third and fourth embodiments described above.

  Note that the number, position, shape, and the like of the constituent members in each of the above-described embodiments are not limited to those described above, and can be set to a suitable number, position, shape, and the like for carrying out the present invention. For example, the dielectric film 3 of DVD-RW1 shown in FIG. 1 may be formed by laminating a plurality of layers, and an interface layer may be formed between each film of DVD-RW1. In each of the above-described embodiments, a DVD-RW-equivalent disk is shown as the information recording medium. However, the present invention is not limited to this, and is a medium for recording information by light, and a corresponding recording speed (cover The present invention can be effectively applied to a phase change disk having a wide range. For example, the present invention is effective for DVD + RW, DVD-RAM, and the like. In this case, the information recording apparatus is a drive that handles each of the above media. Further, in each of the above-described embodiments, the β value given by Equation 2 is used as the asymmetry value, but the value given by Equation 1 may be used as the asymmetry value.

  Hereinafter, the effect of the present invention will be specifically described in comparison with a comparative example that is out of the scope of the claims.

Test example 1
In Test Example 1, the information recording medium (DVD-RW) and the information recording apparatus (DVD drive) shown in the first embodiment were manufactured, and the recording power was increased by the method shown in the first embodiment. Adjustments were made, information was actually recorded, this information was reproduced, and jitter of the reproduced signal was evaluated. FIGS. 7A and 7B are graphs showing the recording power dependence of jitter and asymmetry values, with the recording power on the horizontal axis and the jitter and asymmetry values on the vertical axis. The case of 1 × speed recording is shown, and (b) shows the case of 2 × speed recording. The asymmetry value was calculated based on the 11T single signal and the 3T single signal. The wavelength of the laser beam was 650 nm, the numerical aperture (NA) of the objective lens was 0.6, the beam shape of the laser beam was a perfect circle, and its diameter was 0.9 μm. Furthermore, the channel clock frequency at the time of 1 × speed recording was set to 26.16 MHz. Furthermore, in the case of 1 × speed recording, the disk was rotated at a linear velocity of 3.49 m / sec.

  Note that the jitter values shown in FIGS. 7A and 7B are measured using a recording optical head. As described in the first embodiment, the laser beam emitted from the recording optical head has a larger beam diameter and lower rim intensity than the laser beam emitted from the reproducing optical head. For this reason, when the information recorded on the DVD-RW is reproduced by the recording optical head, the jitter is increased by about 2% as compared with the case where the reproducing optical head is used.

  As shown in FIG. 7A, the optimum recording power P1 at the time of 1 × speed recording is 15 mW, and therefore the recording power P2 is P2 = 15 mW × 85/100 = 12.75 mW. Therefore, from FIG. 7A, the asymmetry value A1 is about 0.03, A2 is about 0.01, and therefore the (A1-A2) value is 0.02, which is 0, which is the reference value. .05 or less. Further, as shown in FIG. 7B, the optimum recording power P1 at the time of double speed recording is 13.7 mW, and therefore the recording power P2 is P2 = 13.7 × 85 / 100≈11.65 mW. It was. Therefore, from FIG. 7B, the asymmetry value A1 is about 0.01 and A2 is about -0.11, and therefore the (A1-A2) value is 0.12, which is the reference value. It was 0.05 or more. This means that OPC using an asymmetry value, that is, the β method does not work well for 1 × speed recording, and that it functions without problem for 2 × speed recording.

  Therefore, the DVD-RW cannot use a method using an asymmetry value as OPC when performing 1 × speed recording, and can use a method using an asymmetry value as OPC when performing 2 × speed recording. Indicators to indicate are recorded. Specifically, LPP Field. In the pre-pit data frame which is the 12th relative address of ID6, “0000b” indicating that an asymmetry value can be used at the time of double speed recording is recorded in the upper 4 bits, and at the time of 1 time speed recording in the lower 4 bits. “0001b” indicating that the asymmetry value cannot be used is recorded. That is, the index indicates the availability of β value in OPC.

  Next, the DVD-RW was inserted into the DVD drive, OPC was performed, a recording operation was performed, and jitter was measured. At this time, OPC was performed by two methods. That is, Example No. 1, after reading the index recorded on the DVD-RW, based on this index, if the index indicates that an asymmetry value can be used, the β method is selected as OPC. However, when the asymmetry value indicates that it cannot be used, the γ method was selected as the OPC. On the other hand, Comparative Example No. In 2, the β method was always selected as OPC without reading the index from the DVD-RW. The results are shown in Table 3. For DVD-R / RW, an optical head for reproduction is used when measuring the quality of a recording signal. Therefore, the jitter values shown in Table 3 are measured with an optical head for reproduction conforming to the DVD-RW standard. For this reason, the jitter value is generally lower than the jitter values shown in FIGS.

  As shown in Table 3, Example No. In No. 1, since OPC was selected based on the index, good jitter of 8% or less was obtained in both 1 × speed recording and 2 × speed recording. In contrast, Comparative Example No. In No. 2, since the β method was used regardless of the index, the jitter value was an extremely high value of 12.5% in 1 × speed recording which cannot be used originally. This is a result of Comparative Example No. In 1 × speed recording of 2, this means that OPC did not function well and a problem occurred.

  From the above, it was proved that the DVD-RW shown in the first embodiment described above is a highly reliable medium in the recording operation because the index is recorded. Further, it has been proved that the drive that reads the index shown in the first embodiment and determines the OPC operation based on the index is a highly reliable drive like the medium.

Test example 2
In Test Example 2, the recording power was adjusted by the method shown in the fifth embodiment, information was actually recorded, this information was reproduced, and the jitter of the reproduced signal was evaluated. FIGS. 8A and 8B are graphs showing the recording power dependence of jitter and asymmetry values, with the recording power on the horizontal axis and the jitter and asymmetry values on the vertical axis. The case of 1 × speed recording is shown, and (b) shows the case of 2 × speed recording. In Test Example 2, the multi β method was performed as the β method. That is, the asymmetry value β3 is calculated based on the 11T single signal and the 3T single signal, the asymmetry value β4 is calculated based on the 11T single signal and the 4T single signal, and β3 and β4 are equal to each other. The power is the optimum recording power. The calculation of (A1-A2) value was performed based on β3. The other asymmetry values and jitter measurement conditions in this test example are the same as in Test Example 1 described above.

  As shown in FIG. 8A, the optimum recording power P1 at the time of 1 × speed recording is 13.6 mW, and therefore the recording power P2 is P2 = 13.6 × 85 / 100≈11.6 mW. Therefore, from FIG. 8A, the asymmetry value A1 is about 0.02, A2 is about -0.02, and therefore the (A1-A2) value is 0.04, which is the reference value. It was less than 0.05. Further, as shown in FIG. 8B, the optimum recording power P1 at the time of double speed recording is 14.0 mW, and therefore the recording power P2 is P2 = 14.0 × 85/100 = 11.9 mW. It was. Therefore, from FIG. 8B, the asymmetry value A1 is about 0.02, A2 is about -0.07, and therefore the (A1-A2) value is 0.09, which is the reference value. It was 0.05 or more. This means that OPC using an asymmetry value, that is, the multi-β method does not function well in 1 × speed recording, and that it functions without problem in 2 × speed recording.

  As described above, the recording power at which β3 and β4 are equal to each other at the time of 1 × recording is about 13.6 mW. However, the recording power that minimizes the jitter is 15 mW in the measured range, and they do not match. This indicates that the multi-β method is not working well. On the other hand, in the double speed recording, the recording power in which β3 and β4 are equal to each other and the recording power in which the jitter is minimum are both about 14.0 mW, and both values are the same. . This indicates that the multi-β method is working well.

  Therefore, the DVD-RW is recorded with an index indicating that an asymmetry value cannot be used as OPC when performing 1 × speed recording, and an asymmetry value can be used as OPC when performing 2 × speed recording.

  Next, the disc was inserted into the drive, OPC was performed, recording was performed, and jitter was measured. At this time, similar to Test Example 1 described above, OPC was performed in two ways. That is, Example No. In No. 3, after reading the index recorded on the DVD-RW, the multi-β method or the γ method was selected as the OPC based on the index. On the other hand, Comparative Example No. In No. 4, the multi-β method was always selected as the OPC operation without reading the index from the DVD-RW. The results are shown in Table 4. The jitter values shown in Table 4 were measured with a reproducing optical head compliant with the DVD-RW standard. For this reason, the values are generally lower than the jitter values shown in FIGS.

  As shown in Table 4, Example No. In No. 3, since OPC was selected based on the index, good jitter of 8% or less was obtained in both 1 × speed recording and 2 × speed recording. In contrast, Comparative Example No. In No. 4, since the multi-β method was used regardless of the index, the jitter value was extremely high at 11.9% in the 1 × speed recording which cannot originally use the multi-β method. This is a result of Comparative Example No. In 1 × speed recording of 4, this means that OPC did not function well and a problem occurred.

  As described above, it is understood that the recording power can be adjusted stably and satisfactorily by embedding the index in the DVD-RW as the medium and the DVD drive selects the OPC method based on the index.

Test example 3
In Test Example 3, the DVD drive shown in the sixth embodiment described above was used to adjust the recording power for the DVD-RW on which the above-mentioned index was not recorded, and the information was actually recorded. This information was reproduced and the jitter of the reproduced signal was evaluated. That is, a DVD-RW in which the index is not recorded is used as a medium, an information recording apparatus measures an asymmetry value of the medium, and calculates a value of (A1-A2) from this measurement result. Was compared with a reference value (0.05), and an apparatus having a function of selecting a β method or a γ method as OPC was used. The other asymmetry values and jitter measurement conditions in this test example are the same as in Test Example 1 described above.

  The DVD-RW was inserted into the DVD drive, OPC was performed, a recording operation was performed, and jitter was measured. At this time, OPC was performed by two methods. That is, Example No. 5, first, the asymmetry value of the DVD-RW is measured, the value of (A1-A2) is calculated and compared with the reference value, and it is determined whether the asymmetry value is usable, and then based on this determination. Therefore, the β method or the γ method was selected as the OPC. On the other hand, Comparative Example No. In 6, the above-described determination was not performed, and the β method was always selected as OPC. The results are shown in Table 5. Note that the jitter values shown in Table 5 were measured with a reproducing optical head.

  As shown in Table 5, Example No. 5, the (A1-A2) value of DVD-RW was measured before OPC, and OPC was selected based on the measurement result. Jitter was obtained. In contrast, Comparative Example No. In No. 6, since the β method was always used, the jitter value was an extremely high value of 11.9% in the 1 × speed recording which cannot be originally used. This is a result of Comparative Example No. In 1 × speed recording of 6, this means that OPC did not function well and a problem occurred. From the above, it can be seen that the drive that measures the (A1-A2) value of the medium before OPC and determines the OPC operation based on the measurement result is a highly reliable drive.

It is sectional drawing which shows DVD-RW which is the information recording medium which concerns on the 1st Embodiment of this invention. In (a) and (b), the horizontal axis represents the type of the medium (DVD-RW), the vertical axis represents the value of (A1-A2), and the recording power P2 is 90% of the optimum recording power P1. It is a graph which shows the value of (A1-A2) at the time of intensity | strength, (a) shows the measurement result at the time of 1 time speed recording, (b) shows the measurement result at the time of 2 time speed recording. In (a) and (b), the horizontal axis represents the type of the medium (DVD-RW), and the vertical axis represents the value (A1-A2). The recording power P2 is 85% of the optimum recording power P1. It is a graph which shows the value of (A1-A2) at the time of intensity | strength, (a) shows the measurement result at the time of 1 time speed recording, (b) shows the measurement result at the time of 2 time speed recording. It is a flowchart figure which shows the manufacturing method of DVD-RW which concerns on the 2nd Embodiment of this invention, and the recording method which concerns on 4th Embodiment. It is a block diagram which shows the DVD drive in the 3rd Embodiment of this invention. It is a block diagram which shows the DVD drive in the 6th Embodiment of this invention. (A) and (b) are graphs showing the recording power dependence of jitter and asymmetry values in Test Example 1, with recording power on the horizontal axis and jitter and asymmetry values on the vertical axis. ) Shows the case of 1 × speed recording, and (b) shows the case of 2 × speed recording. FIGS. 8A and 8B are graphs showing the recording power dependence of jitter and asymmetry values in Test Example 2, with the recording power on the horizontal axis and the jitter and asymmetry values on the vertical axis. (A) shows the case of 1 × speed recording, and (b) shows the case of 2 × speed recording. It is a graph explaining the definition of an asymmetry value, taking time on the horizontal axis and taking the output of the signal on the vertical axis. It is a graph explaining the definition of β value, taking time on the horizontal axis and taking the output of the signal from which the DC component is removed on the vertical axis. FIG. 5 is a graph showing the correlation between recording power, asymmetry value, and jitter, with recording power on the horizontal axis and asymmetry values and jitter values on the vertical axis.

Explanation of symbols

1; DVD-RW
2; Substrate 3; Dielectric film 4; Phase change recording film 5; Dielectric film 6; Reflective film 11; DVD drive 12; Spindle driving device 13; Optical head 14;
15; objective lens 16; photodetector 17; beam splitter 18; RF circuit 19; EFM decoder 20; LPP decoder 21; A1-A2 information discriminator 22; system controller 23; OPC controller 24; EFM encoder 25; 26; Servo controller 31; DVD drive 32; A1-A2 information checker 33; A1-A2 information checker 34; DVD-RW

Claims (13)

A second recording power obtained by measuring a first asymmetry value in the first recording power using the first recording power that minimizes jitter and multiplying the first recording power by a coefficient of 0.85. Measuring a second asymmetry value using P2 and generating an index indicating whether the asymmetry value can be used for OPC using the first asymmetry value and the second asymmetry value; A characteristic index generation method. When the difference between the first asymmetry value and the second asymmetry value is 0.05 or more, an index indicating that the asymmetry value can be used for OPC is created, and the first asymmetry value and the first asymmetry value 2. The index generation method according to claim 1, wherein an index indicating that the asymmetry value cannot be used for OPC is created when a difference between 2 and the asymmetry value is less than 0.05. A recording condition adjusting method for an information recording medium, wherein asymmetry values obtained from a signal recorded on the information recording medium are compared with at least two asymmetry values under the recording condition, and the recording condition is determined based on the comparison result. A method for adjusting a recording condition of an information recording medium, characterized in that an adjustment method is determined. The first asymmetry value in the first recording power at which the jitter is minimized is compared with the second asymmetry value in the second recording power obtained by multiplying the first recording power by a coefficient of 0.85. The recording condition adjusting method for an information recording medium according to claim 3. When the difference between the first asymmetry value and the second asymmetry value is 0.05 or more, the recording condition is adjusted using the asymmetry value, and the first asymmetry value and the second asymmetry value are adjusted. 5. The method for adjusting a recording condition of an information recording medium according to claim 4, wherein the recording condition is not adjusted using an asymmetry value when the difference between and is less than 0.05. A second recording power obtained by measuring a first asymmetry value in the first recording power using the first recording power that minimizes jitter and multiplying the first recording power by a coefficient of 0.85. The second asymmetry is measured, the difference between the first asymmetry value and the second asymmetry value is measured, and the difference between the first asymmetry value and the second asymmetry value is 0.05 or more. Is determined that the asymmetry value can be used for OPC, and when the difference between the first asymmetry value and the second asymmetry value is less than 0.05, the asymmetry value is used for OPC. A method for adjusting a recording condition of an information recording medium, characterized in that it is determined that it cannot be performed. A second recording power obtained by measuring a first asymmetry value in the first recording power using the first recording power that minimizes jitter and multiplying the first recording power by a coefficient of 0.85. The second asymmetry value is measured, and an index indicating whether or not the asymmetry value can be used for OPC is generated using the first asymmetry value and the second asymmetry value, and the generated index A recording condition adjusting method for an information recording medium, wherein the recording condition is adjusted according to the above. When the difference between the first asymmetry value and the second asymmetry value is 0.05 or more, the index indicating whether the asymmetry value can be used for OPC is to use the asymmetry value for OPC. 8. The difference between the first asymmetry value and the second asymmetry value is less than 0.05, indicating that the asymmetry value cannot be used for OPC. A recording condition adjusting method for the information recording medium described. In an information recording apparatus for recording information by irradiating light on an information recording medium, adjustment for adjusting the intensity of the recording light based on the correlation between the asymmetry value of the information recording medium and the intensity of the recording light A signal recording unit for recording one signal with light of one intensity on the information recording medium and recording another signal with light of another intensity, and an asymmetry value of the one signal and other signals A selection unit that measures an asymmetry value to calculate these differences, and activates the adjustment unit when the difference is greater than or equal to a reference value; and a recording unit that records information by irradiating the information recording medium with light. And an information recording apparatus. When there is another adjustment unit that adjusts the intensity of the recording light based on the amplitude of a reproduction signal of information recorded on the information recording medium, and the selection unit has the difference less than the reference value The information recording apparatus according to claim 9, wherein the other adjustment unit is operated. The information recording apparatus according to claim 9, wherein the reference value is 0.05. 10. The one intensity is an intensity that minimizes jitter of a signal recorded by light of this intensity, and the other intensity is 0.85 times the intensity of the one. 12. The information recording device according to any one of 11 to 11. The information recording apparatus according to claim 9, wherein the information recording medium is a DVD-RW.

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