JPWO2005008646A1 - Data recording apparatus and method for recordable optical disk - Google Patents

Abstract

Provided is a data recording apparatus for a recordable optical disc in which the shape distortion of a recording mark is small during high speed recording and the waveform distortion of a reproduction signal is reduced. The recording strategy setting unit (22) adds an auxiliary pulse between the top pulse and the last pulse of the recording pulse according to the amount of waveform distortion of the reproduction signal when the recording speed such as 8 × speed set by the user is high. The recording strategy to be set is set in the recording power determination unit (12). As a result, the thermal energy per unit time at the center of the recording mark can be increased, and the recording mark in the radial direction of the optical disk is reduced due to insufficient heat, resulting in the recording mark shape becoming a drum shape. The distortion of the reproduction waveform is reduced.

Description

  The present invention relates to a data recording technique for a recordable optical disc, and more particularly to a method for determining a recording strategy which is a condition required for a recording pulse based on a recording pattern.

In recent years, an optical information recording technique, that is, a data recording technique on a recordable optical disc has been remarkably developed. Accordingly, various types of optical recording / reproducing apparatuses, that is, optical disk recording / reproducing apparatuses, have been developed. In particular, a device applied as an external recording device of a computer, such as a DVD-RAM drive, has already begun to spread widely.
Recordable optical disks are classified into write-once optical disks and rewritable optical disks. The write-once optical disc refers to an optical disc capable of recording data only once, and includes CD-R (Recordable) and DVD-R.
Creation of a recording mark on a write-once optical disc is performed as follows. The recording layer of a write-once optical disc contains an organic dye, which decomposes when irradiated with a laser having a predetermined power. As a result, the optical reflectivity particularly decreases. Thus, the portion of the recording layer that has been irradiated with the laser becomes a recording mark.
In a write once optical disc, data recording is limited to one time for the following reason. When a recording mark is created, a large amount of heat is generated in the laser irradiation portion of the recording layer, and the heat deforms the surrounding resin or the like. Since these deformations are irreversible, they cannot be returned to the state before the laser irradiation. Therefore, data recording is limited to once in a write-once optical disc.
The rewritable optical disk refers to an optical disk that can be rewritten and recorded many times, and includes CD-RW (Rewriteable), DVD-RAM, DVD-RW, DVD + RW, and the like.
Among the rewritable optical disks, in the phase change optical disk, the recording mark is created as follows. The recording layer of the phase change optical disc includes an alloy having two types of solid phases, a crystalline phase and an amorphous phase. The optical reflectance of the recording layer is high in the crystalline phase and low in the amorphous phase. Therefore, the amorphous phase portion of the recording layer becomes a recording mark. Creation of a recording mark, that is, transition from a crystalline phase to an amorphous phase is realized as follows. The recording layer is irradiated with a pulse of a relatively high power laser. Thereby, a narrow range of the recording layer is instantaneously heated to a temperature equal to or higher than the melting point, and immediately thereafter, rapidly cooled to a temperature equal to or lower than the vitrification point. As a result, the narrow area of the recording layer transitions to the amorphous phase.
Further, in a phase change optical disc, an existing recording mark can be erased as follows. As described above, the recording mark is an amorphous phase portion of the recording layer. Therefore, in order to erase the recording mark, it is only necessary to transition from the amorphous phase to the crystalline phase within the range of the recording mark. The transition from the amorphous phase to the crystalline phase is realized as follows. A relatively low power laser is irradiated to the recording layer of the rotating rewritable optical disk for a relatively long time. Thereby, a wide range of the recording layer is heated to a temperature higher than the vitrification point and not exceeding the melting point. At that time, the area of the heated recording layer cools slowly after heating. As a result, the wide range of the recording layer transitions to the crystalline phase. In this manner, existing recording marks can be erased from the rewritable optical disk.
In actual data recording on the phase change optical disc, the laser is irradiated while switching between the high power and the low power. As a result, the recording mark can be erased and created at the same time, and the data can be overwritten on the optical disk.
FIG. 7 is a block diagram showing a configuration example of a conventional optical disc recording / reproducing apparatus.
First, a playback system of a conventional optical disk recording / playback apparatus will be described with reference to FIG.
In FIG. 7, the optical disk 30 is rotated around its central axis by the spindle motor 14. The optical head, that is, the pickup 1 irradiates the optical disk 30 with a laser and converts the reflected light into an analog signal as follows. The semiconductor laser 1a outputs a laser having a predetermined power. The power (reproduction power) at that time is so small that the recording layer of the optical disc 30 is not altered. The laser R1 output from the semiconductor laser 1a is focused on the recording layer of the optical disc 30 through the condenser lens 1b, the beam splitter 1c, and the objective lens 1d. Next, the laser R1 is reflected by the recording layer of the optical disc 30, and the reflected laser R2 passes through the objective lens 1d, is reflected by the beam splitter 1c, passes through the detection lens 1e, and is focused on the photodetector 1f. tie. The photodetector 1f detects the intensity of the reflected laser R2 and converts it into an analog signal d1. At that time, the amplitude of the analog signal d1 is substantially proportional to the intensity of the reflected laser R2.
The pickup 1 is moved in the radial direction of the optical disc 30 by a stepping motor (not shown). Accordingly, the focal point of the laser R1 output from the semiconductor laser 1a is moved in the radial direction of the optical disc 30. The head amplifier 2 amplifies the analog signal d1 from the pickup 1 and outputs the analog signal d2 to the equalizer 3. The equalizer 3 shapes the waveform of the analog signal d2 from the head amplifier 2. The binarization unit 4 compares the shaped analog signal d3 with a predetermined threshold value, and binarizes the threshold value as a boundary. Thereby, the analog signal d3 is converted into a digital signal d4. The phase locked loop (PLL) circuit 5 synchronizes the digital signal d4 with a predetermined clock signal, and data is demodulated from the digital signal d5 synchronized with the clock signal.
Next, a recording system of a conventional optical disc recording / reproducing apparatus will be described with reference to FIG.
The recording pattern determination unit 8 determines a recording pattern corresponding to the data intended for recording on the optical disc 30. Here, the recording pattern refers to a rectangular pulse train having a constant height. Each pulse width of the recording pattern indicates the length of the recording mark (mark length), and the pulse interval indicates the length of the recording space (space length). The recording pulse determination unit 9 determines the recording pulse d9 based on the recording pattern d8 determined by the recording pattern determination unit 8. Here, the recording pulse refers to a rectangular wave pulse substantially the same as the laser pulse output from the semiconductor laser 1a. Although the waveform of the recording pulse d9 will be described later, it is different from the waveform of the recording pattern d8. The recording pulse d9 is determined according to a certain condition based on the recording pattern d8. The certain condition is called a write strategy, and is also called a write pulse condition or a write pulse structure. Details of the recording strategy will be described later.
The recording power determination unit 12 determines the laser power of the semiconductor laser 1a during data recording. The power value determined thereby is called recording power. The determined recording power d12 is output to the laser driving unit 13. The laser driver 13 controls the drive current d13 to the semiconductor laser 1a. Accordingly, the drive current d13 flows through the semiconductor laser 1a with a magnitude corresponding to the recording power d12. As a result, the semiconductor laser 1a outputs a laser R1 having a power corresponding to the recording power d12.
Next, a configuration for correcting the recording strategy and calibrating the recording power will be described.
The shape of the recording mark formed by laser irradiation is not uniquely determined only by the recording pulse and the recording power. For example, the cooling rate of the recording layer depends on the environmental temperature at the time of recording. Further, the wavelength of the laser of the semiconductor laser varies substantially in proportion to the temperature variation of the semiconductor laser. For example, since the light absorption characteristic of the organic dye contained in the recording layer of DVD-R depends on the wavelength of the absorbed light, the change in the wavelength of the laser changes the absorption energy by the recording layer. In addition, the laser wavelength of the semiconductor laser, the structure of the optical disk, and the like usually vary around the standard value for each product.
The shape of the recording mark varies depending on the variation factors as described above. Accordingly, the recording mark shaping accuracy, particularly the edge positioning accuracy, cannot be sufficiently improved by simply determining the recording pulse and the recording power according to the recording strategy and the recording power condition as per the standard. As a result, the error rate of the actually recorded data cannot be sufficiently reduced. Therefore, the recording strategy is corrected and the recording power is calibrated for each optical disc and optical disc recording / reproducing apparatus. Thereby, the optimum recording pulse and recording power are determined.
A conventional optical disc recording / reproducing apparatus has, for example, the following configuration for the purpose of correcting the recording strategy and calibrating the recording power.
The β value calculation unit 11 calculates an asymmetry (β) value of the analog signal d2 from the head amplifier 2. Here, the β value of the analog signal is defined by the following equation based on the maximum value a and the minimum value b of the analog signal.
β = (a + b) / (ab)
That is, the β value corresponds to a value obtained by normalizing the center value ((a + b) / 2) in the vertical direction of the analog signal waveform by the amplitude (ab), and represents the quality of the reproduction signal.
Further, the β value of the analog signal is a parameter for determining the recording power of the semiconductor laser 1a as follows. The analog signal d1 reproduced by the pickup 1 is binarized by a binarization unit 4 with a predetermined threshold as a boundary. At that time, if the center value in the vertical direction of the waveform of the analog signal d1 deviates from the threshold value, the reproduction accuracy of the original digital data decreases. That is, the error rate of the digital data changes depending on the β value. Therefore, the β value of the analog signal d1 must be selected as an optimum value so that the error rate is equal to or lower than a predetermined allowable value. Since the β value of the analog signal d1 is substantially determined by the optical reflectivity and shape of the recording mark of the optical disc 30, it is determined by the recording power of the laser R1 emitted from the semiconductor laser 1a. Conversely, when the β value of the analog signal d1 is determined, the recording power corresponding to them can be determined. The correspondence between the β value of the analog signal and the recording power is called a recording power condition.
The optical disc 30 records a history of recording strategies and recording power conditions in data recording performed in the past, along with standard recording strategies and standard recording power conditions defined in the standard. The recording strategy demodulator 6 demodulates the recording strategy d6 from the digital signal d5 output by the PLL circuit 5 and outputs it to the recording strategy corrector 7. On the other hand, the recording power condition demodulator 10 demodulates the recording power condition d10 from the digital signal d5 and outputs it to the recording power determination unit 12.
The jitter detector 15 receives the digital signal d4a from the binarizer 4 and the shift from the clock signal of the digital signal d4 from the PLL circuit 5, that is, the jitter d5a, and the jitter d15a and the pulse at the front end of the pulse of the digital signal d4. Jitter d15b at the rear end is detected and output to the recording strategy correction unit 7.
The recording strategy correction unit 7 stores the input recording strategy d6 in the internal memory, and at the time of correcting the stored recording strategy, the jitter d15a at the front end of the pulse of the digital signal d4 and the jitter d15b at the rear end of the pulse, respectively. Compare with a predetermined tolerance. The recording strategy correction unit 7 stores the comparison result in association with the recording strategy stored at that time. Thereafter, the recording strategy correction unit 7 corrects the recording strategy by a predetermined correction value, and after the correction, stores the recording strategy d7 and outputs it to the recording pulse determination unit 9.
Next, correspondence between recording patterns and recording pulses will be described below.
FIG. 8 is a diagram showing the relationship between the recording pattern d8, the recording pulse d9, the laser pulse LP, and the recording mark pattern RM when recording is performed at a normal speed using a DVD-R as the optical disc 30. Here, the unit of each pulse width is represented by T. The unit length T corresponds to one cycle (clock cycle) of the clock signal. In particular, the pulse width and the pulse interval of the recording pattern are both set to an integer multiple of the clock period T.
When the recording layer of the DVD-R is irradiated with the laser from the semiconductor laser 1a, the heat from the laser diffuses from the irradiated portion to the surroundings. In particular, heat propagates back and forth along the groove of the DVD-R. Furthermore, in DVD-R, both the mark length and the space length are short. Therefore, if the waveform of the laser pulse is made substantially the same as the recording pattern, the heat of the laser diffuses from the irradiated portion, and a recording mark is formed in a wider range than the irradiated portion. In addition, heat can easily reach the preceding and following recording marks through the recording space. As a result, the shape of the recording mark is distorted. Due to this distortion, the edge of the recording mark shifts from the position corresponding to the recording pattern, and an error occurs in data recording.
For the purpose of avoiding the above distortion, the recording pulse is conventionally set as follows. In particular, one pulse of a recording pattern is associated with a recording pulse train composed of shorter pulses. As a result, the amount of heat applied from the laser pulse to the recording layer of the DVD-R when one recording mark is formed is suppressed.
One pulse of the recording pattern has a width that is an integral multiple of the clock period T. Here, the shortest pulse width of the recording pattern is set to three times the clock period T (here, T1 = T). The recording pulse is made to correspond to the pulse as follows.
First, if the recording pattern length is 7T1 like the pulse P1 of the recording pattern d8, the leading pulse of the recording pulse d9, that is, the fall of the top pulse P10 (pulse width Tt1) is detected from the front end of the pulse of the recording pattern d8. It is generally fixed at the position of the shortest pulse width 3T1. The period from the fall of the top pulse P10 to the rear end of the pulse P1 of the recording pattern is constituted by a pulse of 1T1 period (logic “L” period is Sm, logic “H” period is Tm), that is, a multi-pulse train P11. The rear end of the multi-pulse train P11 substantially coincides with the rear end of the pulse P1 of the recording pattern d8. Further, if the shortest recording pattern length is 3T1 as in the case of the pulse P2 of the recording pattern d8, the rear end coincides with the falling edge of the top pulse P20. The front end of the top pulse P20 is set to be delayed by a predetermined length (hereinafter referred to as front end delay) F2 from the front end of the pulse P2 of the recording pattern d8. Thereby, the top pulse P20 is shorter than the shortest recording pattern length 3T1 of the recording pattern d8. The front end delay of the top pulse P10 is F1.
The laser pulse LP from the semiconductor laser 1a is irradiated with substantially the same waveform as the recording pulse d9. As shown in FIG. 8, the laser pulse LP at this time corresponds to the top pulse P10 of the recording pulse corresponding to the laser pulse 53, the multi-pulse train corresponding to the laser pulse train 54, and the top pulse P20 corresponding to the laser pulse 55. To do. The peak value L1 of the laser pulse LP represents the recording power of the laser. By the irradiation of the laser pulse, a row of recording marks M and recording spaces S as shown in FIG. 8 is formed on the recording layer of the optical disc 30 as the recording mark pattern RM.
In FIG. 8, as apparent from a comparison between the recording pattern d8 and the recording mark pattern RM, the recording pattern d8 and the columns of the recording mark M and the recording space S correspond well.
FIG. 9 is a diagram showing the relationship between the recording pattern d8, the recording pulse d9, the laser pulse LP, and the recording mark pattern RM when recording is performed at 4 × speed using the DVD-R as the optical disc 30. In FIG. 9, T2 corresponds to 1/4 of the clock cycle T at the same speed (T2 = T / 4).
When the recording pattern length is 7T2 (5T2 or more) like the pulse P1 of the recording pattern d8 shown in FIG. 9, not only the same multi-pulse method as the recording pulse at the same speed but also one pulse of the recording pattern The recording pulse d9 comprising the top pulse P10 (rising P10a, falling P10b, pulse width Ttop), the last pulse P11 (rising P11a, falling P11b, pulse width Tlast) and DC power (from P10b to P11a) is also adopted. Yes. When the recording pattern length is P2 having the shortest pulse width 3T2, the recording pulse is only the top pulse 20 (rising edge P20a, falling edge P20b, pulse width Tt2).
In the case of quadruple speed, considering that the rise and fall of the laser pulse LP affect the formation of the recording mark by making the pulse width 1/4 compared with the recording pulse of the same speed, the multi-speed The pulse train is not used. At the same speed, the width of the multi-pulse train was controlled. However, in the case of the quadruple speed, instead of the multi-pulse train, the level Lm1 of the DC power 64 is set to the peak value Lo1 of the laser pulse LP as shown in FIG. By controlling, the amount of heat given from the laser pulse LP to the recording layer of the DVD-R is suppressed. As a result, it is possible to prevent the formation of excessive recording marks and the propagation of excessive heat to other recording marks.
As shown in P1 of FIG. 9, if the recording pattern length is 7T2, the rear end pulse of the laser pulse LP, that is, the last pulse 65 is controlled with the same recording power L01 as the top pulse 63. The falling edge of the last pulse 65 substantially coincides with the falling position P1b of the pulse P1 of the recording pattern. Further, if the pulse of the recording pattern d8 is the shortest pulse 3T2 as in P2 of FIG. 9, the laser is applied to the falling position P2b of the pulse P2 of the recording pattern d8 with a single pulse as in the case of the same speed. The fall of the top pulse 66 of the pulse LP is slightly delayed by about 0.2T2. The front end delay F2 of the top pulse P20 is set to about 1T2. The pulse width Tt2 of the top pulse P20 is shorter than the shortest pulse width 3T2 of the recording pattern d8.
The waveform of the laser pulse LP is as shown in FIG. By irradiating the laser pulse, a row of recording marks M and recording spaces S as shown in FIG. 9 is formed on the recording layer of the optical disc 30 as the recording mark pattern RM. In the case of quadruple speed, the record pattern d8 corresponds to the row of the record mark M and the record space S as well as the same speed.
In the present specification, as described above, the condition for determining the waveform of the corresponding recording pulse, particularly the positions of both ends of the pulse, based on the mark length and the space length of the recording pattern is referred to as a recording strategy.
For example, the recording strategy for DVD-R and DVD-RW is a condition for determining the following (a), (b), and (c).
(A) Correspondence between pulse width of recording pulse multi-pulse train and mark length of recording pattern
(B) Leading edge delay of top pulse of recording pulse
(C) Combination of recording pattern mark length and previous space length
On the other hand, the recording strategy for the DVD-RAM includes the condition for (b) above, and (d) the last end of the multi-pulse train, or the rear end of the last pulse following the multi-pulse train, the rear end of the corresponding pulse of the recording pattern. It includes a condition for a more advanced amount (rear end advance).
Next, the determination of the recording strategy and the recording power condition will be described.
In the conventional optical disc recording / reproducing apparatus shown in FIG. 7, the recording strategy and the recording power condition to be set for each of the recording pulse determining unit 9 and the recording power determining unit 12 must be determined at the start of data recording.
A standard recording strategy and a standard recording power condition are recorded in advance on the optical disc 30, respectively. Further, a history of recording strategies and recording power conditions at the time of recording performed in the past is recorded. In the conventional optical disc recording / reproducing apparatus, at the start of data recording, first, one is selected from each of the recording strategy and recording power condition recorded on the optical disc 30 and read out from the optical disc 30 as an initial condition. The reading is the same as the normal data reading.
That is, the analog signal d1 from the pickup 1 is converted into a digital signal d5 through the head amplifier 2, the equalizer 3, the binarization unit 4, and the PLL circuit 5. From the digital signal d5, the recording strategy demodulator 6 demodulates the initial recording strategy, and the recording power condition demodulator 10 demodulates the initial recording power condition. The demodulated recording strategy d6 is output to the recording strategy correction unit 7, where it is stored. Further, the demodulated recording strategy d 6 is input to the recording pulse determining unit 9 through the recording strategy correcting unit 7. On the other hand, the demodulated recording power condition d 10 is input to the recording power determination unit 12.
The conventional optical disc recording / reproducing apparatus as described above is required to shorten the time required for recording. In order to meet the demand, it is necessary to increase the rotation speed (recording speed) of the optical disc during recording.
However, as the recording speed is increased, the distortion phenomenon of the recording mark has become remarkable. This has become clear from the following experiments and considerations based on the results.
10 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, and a recording pattern d8 when recording is performed at 8 × speed using a DVD-R as the optical disc 30 and adopting the recording strategy at 4 × speed shown in FIG. It is a figure which shows the relationship of the recording mark pattern RM. In FIG. 10, T3 corresponds to 1/8 of the clock cycle T at the normal speed (T3 = T / 8).
As is clear from a comparison between FIG. 9 and FIG. 10, the recording pattern d8 and the recording pulse d9 have substantially the same shape. Here, substantially the same shape means that the recording pattern d8 and the pulse width and pulse interval of the recording pulse d9 have the same numerical value when expressed in units of clock cycles.
9 and FIG. 10, the portions corresponding to FIG. 9 are denoted by the same reference numerals so that the recording patterns d8 and the recording pulses d9 are substantially the same. . The unit length T3 of the pulse width in FIG. 10, that is, one cycle of the clock signal corresponds to ½ times the clock cycle T2 in FIG. Therefore, the actual lengths of the recording pattern d8 and the recording pulse d9 are 1/2 of FIG. 9 in FIG. On the other hand, the rotation speed of the optical disk is twice that of FIG. 9 in FIG.
If the shape of the recording mark does not depend on the recording speed, the same shape recording mark should be obtained by simply changing the recording power between FIG. 9 showing the case of 4 × speed and FIG. 10 showing the case of 8 × speed. It is. However, when FIG. 9 is compared with FIG. 10, the recording mark M <b> 1 shown in FIG. 10 is formed to spread in the radial direction of the optical disc 30. In other words, the necessary recording power increases in proportion to the linear velocity, but as the irradiation power increases with respect to the recording track of the optical disc 30, the phenomenon that the recording mark M1 spreads in the radial direction occurs. This is because the size of the laser beam spot is substantially the same regardless of the recording speed and recording power, but the thermal energy increases, so the recording mark M1 becomes larger and the amount of reflected light also decreases.
In particular, in the case of DVD-R, when the recording mark M1 spreads in the radial direction, the groove shape of the track causes plastic deformation (58 in FIG. 10) due to the influence of laser heat, and wobble generated by the diffracted light of the groove signal. The S / N of the signal and land pre-pit (hereinafter referred to as LPP) signal formed in the land portion deteriorates, and the standard value cannot be satisfied.
Since the wobble signal and the LPP signal are generated from the differential output signal of the photodetector 1 f of the pickup 1, the S / N is reduced by forming a recording mark after recording as compared to the unrecorded state. There is a tendency. The higher the power, the stronger the tendency. In particular, the LPP records ECC (Error Correction Code) block addresses, which are absolute physical addresses continuously from the inner circumference to the outer circumference. A problem will occur.
As a countermeasure, in the recording strategy, the ratio Lo2 / Lm2 of the peak value with respect to the DC power level of the laser pulse LP shown in FIG. 10 is increased, that is, the DC power level Lm2 is decreased relative to the peak value Lo2. It has been considered to reduce the recording power corresponding to the intermediate portion of the recording mark (between the top pulse and the last pulse) so that the recording mark does not spread in the radial direction (for example, JP-A-2000-2000). 149259).
However, by reducing the DC power level Lm2, the radial expansion of the recording mark up to the recording mark length 7T3 can be controlled. However, as shown in FIG. 11, the recording pattern d8 having a recording pattern length of 11T3 is controlled. A phenomenon was observed in which distortion Ma2 occurred in the longer recording mark M2 in the circumferential direction corresponding to the pulse P3. In FIG. 11, RF represents a reproduction signal corresponding to the amount of light when the recording mark M2 is reproduced. In order to prevent the LPP error from deteriorating, the recording was performed with the DC power level Pm2 lowered, but conversely, the central portion became insufficient in heat, the recording mark in the radial direction was reduced, and the recording mark M2 Since the shape has become a drum shape, the reflectance of the central portion increases, and the waveform of the reproduction signal RF that appears as the intensity of reflected light is distorted.
The magnitude of the waveform distortion is represented by (B / A) where B is the distortion amount with respect to the amplitude A, and when (B / A) exceeds a certain amount, the length of the recording mark is shortened and binarized. In some cases, a recording mark may be erroneously detected, and when reproduced by a reproducing apparatus, errors increase and compatibility problems occur.
In particular, if the speed is increased, the influence of overheat and shortage becomes more pronounced depending on the length of each recording mark, and the influence of waveform distortion tends to increase. If the recording film material, the recording film thickness, etc. are adapted so that waveform distortion does not occur in high-speed recording, the waveform distortion tends to occur during low-speed recording. This is because, for example, if the recording film is a film that has little thermal interference during high-speed recording, and if recording at low speed, the thermal reactivity will deteriorate, the reflectance will increase locally, and the amount of reflected light will become strong and weak. This is because the waveform of the reproduced signal RF appearing is distorted.
In particular, the longer the recording mark, the more likely the waveform distortion occurs. This is because, for example, according to “DVD-R for General Ver. 2.0”, the recording power ratio Lo3 / Lm3 is set to be constant regardless of the recording mark length. However, the longer the recording mark length is 11T3 or more, the lower the heat tends to be at the center. However, for example, even if Lm3 is increased and Lo3 / Lm3 is decreased only for a long recording mark of 11T3 or more, the LPP error and wobble jitter are deteriorated only by expanding the recording mark in the radial direction. It will be.

The present invention has been made in view of the above-described problems, and the object of the present invention is to prevent waveform distortion of a recording mark that is difficult to spread in the radial direction and long in the circumferential direction even when data recording is performed at high speed. Provided are a data recording apparatus and a data recording method for a recordable optical disc that can record data with high quality by determining a few optimum recording strategies and recording power conditions and ensuring a sufficient recording power margin. There is.
In order to achieve the above object, a data recording apparatus for a recordable optical disc according to the present invention includes a semiconductor laser for irradiating a laser onto the recordable optical disc with a predetermined recording power, and a laser emitted from the semiconductor laser. Set the recording power and recording pulse width of the recording pulse train necessary to form the recording mark according to the laser drive unit for controlling the recording power and recording pulse width, the recordable optical disc, the recording speed and the recording mark length. In addition, a recording strategy setting unit for adding auxiliary pulses at substantially equal intervals with respect to the front end pulse and rear end pulse of an arbitrary recording pulse train is provided.
According to this configuration, when data is recorded on the optical disc at high speed, the heat energy per unit time at the central portion of the recording mark can be increased by adding an auxiliary pulse. As a result, the recording marks in the radial direction of the optical disk are reduced due to lack of heat, and the distortion of the reproduction waveform caused by the recording mark shape becoming a drum shape can be reduced, as well as wobble jitter and land prepit errors. Deterioration can be controlled.
In order to achieve the above object, a method of recording data on a recordable optical disk according to the present invention includes a step of setting a recording speed as set recording speed information, and a recording mark according to the recording speed information and the recordable optical disk. A step of setting a recording strategy for adding an auxiliary pulse to a position of approximately equal intervals between a front end pulse and a rear end pulse for an arbitrary recording pulse train at the time of formation, and test recording on a recordable optical disc according to the recording strategy Asymmetry represented by β = (a + b) / (ab), where a is the maximum value of the signal obtained by reproducing the recording mark formed by the step and test recording, and b is the minimum value thereof. (Β) A step of calculating a value, a step of comparing the β value with a predetermined allowable value, and a recording pulse train so that the β value is equal to or smaller than the predetermined allowable value. Characterized in that it comprises a step of determining a recording power.
According to this configuration, when recording on a recordable optical disc at high speed, test recording is performed with a recording pulse train in which an auxiliary pulse is added between the top pulse and the last pulse, and the β value and the modulation degree are allowed from the reproduction signal. By determining whether or not the value exceeds the maximum value, it is possible to determine the optimum peak value and DC power level of the recording power. Thus, by controlling the spread of the recording mark in the radial direction of the optical disc during high-speed recording, it is possible to prevent deterioration of wobble jitter and land prepit errors.

FIG. 1 is a block diagram showing a configuration example of a DVD-R recorder as an example of a data recording apparatus for a recordable optical disc according to Embodiment 1 of the present invention.
2 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to Embodiment 1 of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to.
FIG. 3 is a flowchart showing a recording learning method according to Embodiment 1 of the present invention.
4 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to Embodiment 2 of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to.
5 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to Embodiment 3 of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to.
FIG. 6 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to the fourth embodiment of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to.
FIG. 7 is a block diagram showing a configuration example of a conventional optical disc recording / reproducing apparatus.
FIG. 8 is a diagram showing the relationship between the recording pattern d8, the recording pulse d9, the laser pulse LP, and the recording mark pattern RM when recording is performed at the same speed using a conventional optical disc recording / reproducing apparatus.
FIG. 9 is a diagram showing the relationship between the recording pattern d8, the recording pulse d9, the laser pulse LP, and the recording mark pattern RM when recording is performed at 4 × speed using a conventional optical disc recording / reproducing apparatus.
FIG. 10 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, when recording is performed at 8 × speed using the recording strategy at 4 × speed shown in FIG. It is a figure which shows the relationship between recording mark pattern RM.
FIG. 11 shows a recording pattern d8 when a recording mark at a speed of 4 × shown in FIG. 9 is used to record a recording mark longer than that in FIG. It is a figure which shows the relationship of the reproduction signal RF with respect to the recording pulse d9, the laser pulse LP, the recording mark pattern RM, and the recording mark pattern RM.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a DVD-R recorder as an example of a data recording apparatus for a recordable optical disc according to Embodiment 1 of the present invention. In FIG. 1, parts having the same configurations and functions as those in FIG. 7 referred to in the description of the conventional example are denoted by the same reference numerals and description thereof is omitted. Below, the structure which is mainly different from a prior art example is demonstrated.
The DVD-R 30 is rotated around its central axis by the spindle motor 14. At that time, the rotational speed of the spindle motor 14 is controlled so that the linear velocity of the DVD-R 30 is substantially always constant at the focal position of the laser R1 from the pickup 1. The value of the linear velocity is set to an integral multiple of the standard velocity of 3.49 m / s.
The recording strategy correction unit 7 corrects the recording strategy by a predetermined correction value in accordance with the recording speed d17 set by the recording speed setting unit 17.
The recording pattern determination unit 8 determines a recording pattern corresponding to data intended for recording on the DVD-R 30. Here, the recording pattern is determined according to the mark edge recording method. That is, both ends of the pulse of the recording pattern correspond to both edges of the recording mark. The recording pattern determination unit 8 modulates the data into a recording pattern by 8-16 conversion modulation. After modulation, 1-bit data is assigned to one cycle (clock cycle) 1T of the clock signal from the PLL circuit 5. As a result, the pulse width and pulse interval of the recording pattern are 3T to 11T and 14T. Here, the pulse width and pulse interval of length 3T to 11T are used as data, and the pulse width and pulse interval of length 14T are used as synchronization signals. Further, the recording pattern determination unit 8 stores test recording patterns in the internal memory at the time of recording strategy correction and recording power learning called OPC (Optimum Power Control).
The recording pulse determination unit 9 determines the recording pulse d9 according to the recording strategy based on the recording pattern d8 determined by the recording pattern determination unit 8. The recording power determination unit 12 executes OPC based on the recording power condition at the start of recording of the title, calibrates the recording power based on the β value d11 from the β value calculation unit 11, and the peak value Po3 of the reference recording power. The DC level Pm3 is determined. Specifically, the recording power determination unit 12 performs OPC until the β value becomes 0 to + 5%.
The waveform distortion detection unit 20 mainly detects distortion of a long recording mark of 9 to 14 T in the analog signal d2 from the head amplifier 2. Specifically, the maximum amplitude value d20a in the analog signal d2 and the amplitude decrease d20b due to distortion are detected and supplied to the distortion amount calculation unit 21. The distortion amount calculation unit 21 calculates d20b / d20a as a distortion amount from the maximum amplitude value d20a and the amplitude decrease d20b, determines the magnitude of the distortion amount, and outputs the determination result d21. The recording strategy setting unit 22 adds a middle pulse as an auxiliary pulse between the top pulse and the last pulse based on the determination result d21 from the distortion amount calculation unit 21, or when adding the middle pulse, the pulse width of the middle pulse is set. The information d22 is sent to the recording power determination unit 12.
The recording power d12 determined by the recording power determination unit 12 is output to the laser driving unit 13. The laser drive unit 13 controls the drive current d13 to the semiconductor laser 1a according to the recording power d12. As a result, the semiconductor laser 1a irradiates the laser R1 having a power corresponding to the recording power d12 with substantially the same waveform as the recording pulse d9. As a result, a row of recording marks and recording spaces substantially corresponding to the recording pattern d8 is formed on the recording layer of the DVD-R 30.
FIG. 2 shows a recording signal d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a reproduction signal for the recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to the present embodiment. It is a figure which shows the relationship of RF. In FIG. 2, T3 corresponds to 1/8 of the clock cycle T at the normal speed (T3 = T / 8).
The DVD-R recorder according to the present embodiment employs a recording strategy in which auxiliary pulses are added as follows according to the set recording speed.
First, the semiconductor laser 1a irradiates the DVD-R 30 with a laser pulse LP having a waveform based on the recording pulse d9. The laser pulse LP at that time has a waveform as shown in FIG. The crest value Lo3 and the DC power level Lm3 of the laser pulse LP represent the recording power of the laser. By irradiation of the laser pulse LP, a row of recording marks M3 and recording spaces S3 as shown in FIG. , Formed on the recording layer of DVD-R30. In FIG. 2, as is clear from the comparison between the recording pattern d8 and the recording mark pattern RM, both ends of the recording pattern d8 and both edges of the recording mark M3 correspond well.
The advantages of the present embodiment are described as follows in the example of the recording pattern in FIG. In FIG. 2, a middle pulse P82 having the same recording power Po3 as the top pulse P80 and the last pulse P81 of the recording pulse d9 is used. The recording mark is distorted in the radial direction only by raising and lowering the DC power level Pm3. On the other hand, the pulse width Tmid of the middle pulse P82 is set to a short time of about 1T3 to 2T3, and the heat energy is given in this short time. The recording mark M3 obtained by the 8 × speed recording strategy approaches the recording mark M (FIG. 8) obtained by the 1 × speed recording strategy. Therefore, as indicated by Ma3, the spread distortion in the radial direction of the recording mark M3 can be reduced. Further, the waveform distortion of the reproduction signal RF with respect to the recording mark M3 can be improved from the broken line in FIG. 2 to the solid line.
Therefore, the groove shape is not deformed by laser heat, and it is possible to prevent the jitter of the wobble signal which is a groove signal and the deterioration of the jitter of the land pre-pit signal which is a phase signal with the wobble.
Next, a recording learning method for determining optimum recording power by performing test recording in the DVD-R recorder according to the present embodiment will be described.
FIG. 3 is a flowchart showing a recording learning method according to the present embodiment. In FIG. 3, first, the DVD-R 30 is mounted on the DVD-R recorder (step S1). When the DVD-R 30 is rotated by the spindle motor 14 after the installation of the DVD-R 30 is detected, the pickup 1 refers to the LPP information of the DVD-R 30 and RMA (Recording Management Area), and performs RMD (Recording Management Data). Read (step S2).
Next, the user of the DVD-R recorder sets the recording speed by the recording speed setting unit 17 (step S3). Specifically, a positive integer indicating the magnification of the set recording speed with respect to the standard recording speed of 3.49 m / s is input as the set recording speed information.
Step S4 is executed as follows.
Based on the recommended recording strategy read from the LPP and RMA according to the set recording speed, OPC is executed based on the recording power condition at the start of title recording. The recording pattern determination unit 8 outputs a test recording pattern d8 different from the above. The recording pulse determination unit 9 determines a test recording pulse d9 from the test recording pattern d8. The recording power determination unit 12 sets the recording power corresponding to the test recording pulse d9 to a predetermined initial value. At that time, the initial value is determined as follows. First, the recording power corresponding to the target β value is selected from the recording power conditions. For example, it is assumed that the peak value Po3 of the recording power is 16.0 mW. Next, an initial value of the recording power is set to a value smaller than the recording power corresponding to the target β value by a predetermined value. For example, if the predetermined value is 2.0 mW, the initial value is determined to be 14.0 mW. Here, the target β value is set in advance for each type of DVD-R 30 with respect to the DVD-R recorder, for example. With this setting, the error rate of the reproduced digital signal is suppressed to a predetermined allowable value or less. In addition, the target β value may be recorded in the RMA of the DVD-R30. Since the value of the recording power DC level Pm3 exists as recommended recording strategy information read from the LPP and RMA, the recording power ratio Po3 / Pm3 is determined here.
The laser driver 13 drives the semiconductor laser 1a, and the semiconductor laser 1a emits a laser R1 having a power corresponding to the recording power d12. Thereby, a test recording mark is formed on a PCA (Power Calibration Area) of the DVD-R 30.
The pickup 1 irradiates a PCA test recording mark with a laser having a reproduction power and detects the reflected light. The detected reflected light is converted into an analog signal d 1 and further shaped through the head amplifier 2 and the equalizer 3. The β value calculation unit 11 calculates the β value d11 based on the analog signal d2 from the head amplifier 2 (step S5).
The calculated β value d11 is stored in the recording strategy setting unit 22. Thereafter, the recording power is changed by a predetermined step from the initial value, and the above process is repeated. For example, when the initial value is 14.0 mW and the step is 0.5 mW, the recording power set next to the initial value is 14.5 mW.
Thereafter, each time the recording power is changed by one step to form a test recording mark, the β value of the analog signal reproduced from the test recording mark is calculated and stored. Thereby, a correspondence table between the number of times of change in the recording power (number of steps) and the calculated β value, that is, a new recording power condition is obtained. For example, the correspondence table has an initial value of 14.0 mW (number of steps 0), 14.5 mW (number of steps 1), 15.0 mW (number of steps 2), ..., 18.0 mW (number of steps 8). .Beta. Values corresponding to different recording powers by 0.5 mW are stored in association with the number of steps 0-8. A reference recording power Po3 corresponding to the target β value is selected from the recording power condition (step S6).
The waveform distortion detector 20 reads the waveform distortion amount η of the reproduction signal RF for the test recording mark formed with the selected recording power (step S7). The distortion detection unit 20 detects distortion of a reproduction signal with respect to a long recording mark of 9T3 to 14T3 mainly from the analog signal d2 from the head amplifier 2.
The distortion amount calculation unit 21 determines the magnitude of the waveform distortion amount η (step S8). As shown in FIG. 2, A in the reproduction signal RF is the maximum value of amplitude, B corresponds to the decrease in amplitude, and the waveform distortion amount η = (B / A) × 100%. In step S8, for example, when the specified value of η is 10% and η exceeds 10% (YES), it is determined that the middle pulse P82 (FIG. 2) as an auxiliary pulse by the recording strategy setting unit 22 is necessary. If it is 10% or less (NO), it is determined that the middle pulse P82 is unnecessary. The information d22 is sent to the recording power determination unit 12.
When the waveform distortion amount η exceeds 10%, a fixed value of the auxiliary pulse is added as an initial value (step S9). As an auxiliary pulse, as shown in FIG. 2, a pulse P82 having a fixed width with a peak value of recording power Po3 and a pulse width Tmid is added. For example, an auxiliary pulse having a pulse width Tmid = 1T3 is added. Note that the pulse width here may be stored in advance in the memory of the recording apparatus as a value that seems to be optimal based on experiments, and may be called from the memory for each media ID.
On the other hand, if the result of determination in step S8 is that the waveform distortion amount η is 10% or less, it is determined that an auxiliary pulse is not required (step S10), and recording learning is terminated. Therefore, title recording starts in the absence of an auxiliary pulse.
Since the fixed value of the auxiliary pulse is added, the β value of the recording mark is likely to change. Therefore, similarly to steps S4 to S7, the recording power is changed again from the initial value by a predetermined step, the recording power corresponding to the target β value is selected, and the waveform distortion amount of the reproduction signal RF with respect to the test recording mark η is read (step S11).
Next, as in step S8, the distortion amount calculation unit 21 determines the magnitude of the waveform distortion amount η (step S12). If the waveform distortion amount η is 10% or less (YES), the recording learning is terminated. Therefore, an auxiliary pulse having an initial setting value (initial pulse width) is added and title recording starts.
On the other hand, if the waveform distortion amount η is still larger than 10% as a result of the determination in step S12 (NO), the auxiliary pulse setting value (pulse width Tmid) is changed again until the specified value of 10% is satisfied. Steps S11 to S13 are repeated. Similarly, the title recording starts after completing the record learning.
As described above, according to the present embodiment, a recording mark with less distortion can be formed by adding an auxiliary pulse even during high-speed recording. As a result, the error rate of data recorded at a high recording speed can be reduced.
(Embodiment 2)
In the DVD-R recorder according to the second embodiment of the present invention, as in the first embodiment, a recording strategy in which an auxiliary pulse is added as follows according to the set recording speed is adopted, and the block configuration shown in FIG. Take.
4 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to Embodiment 2 of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to. In FIG. 4, T3 corresponds to 1/8 of the clock cycle T at the normal speed (T3 = T / 8).
In the first embodiment, the auxiliary pulse is a single pulse. However, in the present embodiment, as shown in FIG. 4, an auxiliary pulse P30 including, for example, two pulse trains is added. In the case of one pulse, the waveform distortion amount η of the reproduction signal RF can be controlled by changing the pulse width Tmid of the auxiliary pulse. However, in an actual recording apparatus, the control of the pulse width is complicated. there is a possibility. Therefore, in this embodiment, a plurality of auxiliary pulses are used, and the number of auxiliary pulses is increased or decreased to control the waveform distortion amount η.
Next, a recording learning method for determining optimum recording power by performing test recording in a DVD-R recorder will be described. In the first embodiment, the pulse width of the auxiliary pulse is changed in step S13 of the flowchart of FIG. 3, but in this embodiment, the waveform distortion amount η of the reproduction signal RF is reduced by increasing the number of auxiliary pulses. It differs in the point to control.
Since the other steps are the same as those in the first embodiment, those in the first embodiment can be used for the description of these steps.
(Embodiment 3)
In the DVD-R recorder according to the third embodiment of the present invention, as in the first embodiment, a recording strategy in which auxiliary pulses are added as follows according to the set recording speed is adopted, and the block configuration shown in FIG. Take.
5 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to Embodiment 3 of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to. In FIG. 5, T3 corresponds to 1/8 of the clock cycle T at the normal speed (T3 = T / 8).
In the first embodiment, the auxiliary pulse P82 is formed at an intermediate portion between the top pulse P80 and the last pulse P81. However, depending on the optical disk, the amount of heat of the auxiliary pulse may affect the recording mark length. That is, there is a possibility that the front end (or rear edge) becomes long, and it is necessary to change the rising position (or falling position) of the auxiliary pulse depending on the optical disc.
In this embodiment, as shown in FIG. 5, by changing the rising position P82a (or falling position P82b) of the auxiliary pulse P82, the auxiliary pulse P82 is formed at a position where the recording mark length is unlikely to change. The waveform distortion of the reproduction signal RF can be reduced while maintaining good.
Next, a recording learning method for determining optimum recording power by performing test recording in a DVD-R recorder will be described. In the first embodiment, the pulse width of the auxiliary pulse is changed in step S13 of the flowchart of FIG. 3, but in this embodiment, the time until the rising P82a (or falling P82b) of the auxiliary pulse P82a is changed. The difference is that the waveform distortion amount η of the reproduction signal RF is controlled.
Since the other steps are the same as those in the first embodiment, those in the first embodiment can be used for the description of these steps.
(Embodiment 4)
In the DVD-R recorder according to the fourth embodiment of the present invention, as in the first embodiment, a recording strategy in which auxiliary pulses are added as follows according to the set recording speed is adopted, and the block configuration shown in FIG. Take.
FIG. 6 shows a recording pattern d8, a recording pulse d9, a laser pulse LP, a recording mark pattern RM, and a recording mark pattern RM when recording is performed at 8 × speed using the DVD-R recorder according to the fourth embodiment of the present invention. It is a figure which shows the relationship of the reproduction signal RF with respect to. In FIG. 6, T3 corresponds to 1/8 of the clock cycle T at the normal speed (T3 = T / 8).
In the first embodiment, the recording power Lo3 of the auxiliary pulse P82 is set to the same recording power Lo3 as that of the top pulse P80 and the last pulse P81. However, when higher speed recording is performed, the laser power increases and the waveform of the laser pulse LP is increased. May not reach the Lo3 level. Further, the DC level Lm3 of the recording power is not stabilized due to the deterioration of the transient at the fall of the laser pulse LP. Therefore, in the present embodiment, by setting the recording power Po4 of the auxiliary pulse P82, stable recording characteristics can be ensured even when performing higher speed recording. Of course, the recording power Po4 of the auxiliary pulse P82 can be set higher than the recording power Po3 of the top pulse P80 and the last pulse P81.
As described above, according to the present embodiment, by optimizing the recording power of the auxiliary pulse, stable recording characteristics with less waveform distortion of the reproduction signal RF can be ensured even when higher speed recording is performed.
Next, a recording learning method for determining optimum recording power by performing test recording in a DVD-R recorder will be described. In the first embodiment, the pulse width of the auxiliary pulse is changed in step S13 of the flowchart of FIG. 3, but in this embodiment, the waveform distortion is controlled by changing the recording power Po4 of the auxiliary pulse P82. Different.
Since the other steps are the same as those in the first embodiment, those in the first embodiment can be used for the description of these steps.
Industrial Applicability According to the present invention, it is possible to increase the heat energy per unit time at the center of the recording mark by adding an auxiliary pulse when recording data on the optical disc at high speed. . This reduces the recording mark in the radial direction of the optical disk due to insufficient heat and reduces the waveform distortion of the reproduction signal due to the drum shape of the recording mark, and controls the deterioration of wobble jitter and land prepit errors. be able to.

Claims (12)

An apparatus for optically recording data on a recordable optical disc,
A semiconductor laser for irradiating the recordable optical disc with a predetermined recording power; and
A laser drive unit for controlling the recording power and recording pulse width of the laser emitted from the semiconductor laser;
The recording power and the recording pulse width of the recording pulse train necessary for forming the recording mark are set according to the recordable optical disc, the recording speed and the recording mark length, and the front end pulse and the rear end pulse of any recording pulse train are set. A data recording apparatus for a recordable optical disk, comprising: a recording strategy setting unit for adding auxiliary pulses at positions at approximately equal intervals with respect to the end pulse. 2. The data recording apparatus for a recordable optical disc according to claim 1, wherein the recording strategy setting unit arbitrarily sets a pulse width of the auxiliary pulse. 2. The data recording apparatus for a recordable optical disc according to claim 1, wherein the recording strategy setting unit arbitrarily sets the number of auxiliary pulses. The data recording apparatus for a recordable optical disc according to claim 1, wherein the recording strategy setting unit arbitrarily sets a relative position of the auxiliary pulse in a recording pulse train. The data recording apparatus for a recordable optical disc according to claim 1, wherein the recording strategy setting unit arbitrarily sets a recording power of the auxiliary pulse. The data recording apparatus for a recordable optical disc according to claim 1, wherein the recording strategy setting unit sets the auxiliary pulse with a recording mark that is three times or more the shortest recording mark length. A method for optically recording data on a recordable optical disc,
Setting recording speed as set recording speed information;
A step of setting a recording strategy for adding an auxiliary pulse at an approximately equal interval between the front end pulse and the rear end pulse with respect to an arbitrary recording pulse train at the time of recording mark formation according to the recording speed information and the recordable optical disc. When,
Performing test recording on a recordable optical disc in accordance with the recording strategy;
Asymmetry (β) where β = (a + b) / (ab), where a is the maximum value of the signal obtained by reproducing the recording mark formed by the test recording and b is the minimum value thereof. ) Calculating a value;
Comparing the β value with a predetermined tolerance value;
And a step of determining a recording power for the recording pulse train so that the β value is equal to or less than the predetermined allowable value. The data recording method for an optical disc according to claim 7, wherein the data recording method for the recordable optical disc includes a step of arbitrarily setting a pulse width of the auxiliary pulse. 8. The method of recording data on an optical disc according to claim 7, wherein the method of recording data on the recordable optical disc includes a step of arbitrarily setting the number of auxiliary pulses. 8. The method of recording data on an optical disc according to claim 7, wherein the data recording method on the recordable optical disc includes a step of arbitrarily setting a relative position of the auxiliary pulse in a recording pulse train. The data recording method for an optical disc according to claim 7, wherein the data recording method for the recordable optical disc includes a step of arbitrarily setting a recording power of the auxiliary pulse. 8. The method of recording data on an optical disc according to claim 7, wherein the method of recording data on the recordable optical disc includes the step of setting the auxiliary pulse with a recording mark that is at least three times the shortest recording mark length.

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