JP2009087484A - Optical recording and reproducing method and optical recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical recording and reproducing method and optical recording and reproducing device which efficiently optimize a parameter related to a write strategy, especially a pulse width. <P>SOLUTION: The optical recording and reproducing method and optical recording and reproducing device which perform recording on an optical disk using the write strategy in which the parameter to control the pulse width of each record mark is contained, read a width of signal portion corresponding to a space of a recorded signal, compare the widths of the read space portions by pattern length corresponding to marks immediately before and immediately after the space and correct the pulse widths. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical recording / reproducing method and an optical recording / reproducing apparatus for recording data on an optical disc, and in particular, a method for optimizing a write strategy (laser emission waveform rule used for recording) used during recording. It is about.

  In recent years, large-capacity optical discs such as Blu-ray Discs are becoming popular in optical recording / reproducing apparatuses. For such an optical disc, it is necessary to optimize the write strategy used for recording in accordance with the characteristics of the optical disc.

  As a countermeasure, a mark formed by trial writing is read, and a deviation of the signal portion corresponding to the read mark (a difference from an ideal length of the signal portion corresponding to the mark) is evaluated, and the deviation is determined in advance. It has been proposed to repeatedly correct the write strategy so that it falls within the range (see, for example, Patent Documents 1 to 5). There is also a document disclosing the shape of a multi-pulse type write strategy such as Blu-ray Disc (Non-Patent Document 1).

JP 2006-004601 A (1-14 Mitsugu, Fig. 1-16) JP 2006-031915 A (1-13 Mitsugu, Fig. 1-10) JP 2006-048907 A (1-16 Mitsugu, Fig. 1-19) JP 2006-164486 A (1-13 Mitsugu, Fig. 1-17) JP 2007-018582 A (1-11 Mitsugu, Fig. 1-11) Sharp Technical Bulletin, No. 90, December 2004 (pages 11-15)

  In the conventional optical recording / reproducing apparatus, the write strategy is corrected so that the deviation of the signal obtained by reading the pit portion formed by the trial writing falls within a predetermined range. However, the write strategy parameter used for recording is recorded. When using a write strategy that combines multiple parameters that specify the pulse width and phase, rather than a write strategy that specifies only the start and end of the mark, the variation in the deviation is caused by multiple parameters. However, there is a problem that it is not possible to easily optimize all the write strategy parameters.

  The present invention has been made to solve the above-described problems, and the write strategy for recording information on the optical disc, particularly the parameters related to the pulse width, is efficiently optimized for the optical disc. It is an object of the present invention to provide an optical recording / reproducing method and an optical recording / reproducing apparatus which can be made to be able to be realized.

The optical recording / reproducing method of the present invention comprises:
According to a write strategy parameter corresponding to a mark length of recorded data, an optical recording / reproducing method for recording data by irradiating an optical recording medium with laser light and reproducing recorded data,
Depending on the length of the mark of the data to be recorded, the mark is formed by irradiating the laser beam with a multi-pulse type write strategy including a single or a plurality of pulses and including a parameter for controlling the width of the pulse. A recording part forming step of forming and forming a recording part composed of a mark and a space located between the marks;
A space width reading step of reading the width of the signal portion corresponding to the space of the reproduction signal obtained by reading the recording unit;
Any two signal patterns of the reproduction signal composed of a combination of a signal portion corresponding to the space and a signal portion corresponding to marks before and after the signal portion corresponding to the space, the length of the space A pattern detection step of detecting two signal patterns having the same length, the length of one of the marks immediately before and after the space being equal, and the length of the other mark being different from each other;
A space width comparison step of comparing the widths of the signal portions corresponding to the spaces read in the space width reading step of the two signal patterns detected in the pattern detection step;
A pulse width correcting step of correcting the pulse width of the write strategy based on the result of the comparison of the width of the signal portion corresponding to the space;
A writing step of writing to the optical recording medium using the corrected pulse width.

  According to the present invention, the width of the reproduction signal portion corresponding to the space of the recorded data is compared according to the length of the mark immediately before and after the space, and the parameter of the write strategy, particularly the pulse width, based on the comparison result. By correcting this, the pulse width can be optimized at high speed.

Embodiment.
Embodiments of the present invention will be described below with reference to the drawings.
The optical recording method in the embodiment described below performs mark edge recording (PWM recording). Then, according to the data to be recorded on the optical disc, information is recorded by forming a recording mark by causing a semiconductor laser to emit multipulse light according to a write strategy (laser emission waveform rule used for recording). That is, the write strategy used in the following embodiments is a multi-pulse type. In such a multi-pulse type write strategy, parameters relating to the write strategy, particularly the pulse width, are corrected based on the signal width corresponding to the space read from the test-written signal.

  Furthermore, the length of the mark and the space between the marks are expressed in units of the period T of the channel clock used for recording and reproduction of the signal portion corresponding to the mark or space, and Recording is performed by irradiating an optical disc with a light pulse having a pattern corresponding to 2T-9T marks of 1-7 modulation represented by Blu-ray Disc, that is, marks having a clock cycle number n of 2-9. And

  The drawings referred to in the embodiments of the present invention will be described below. FIG. 1 is a diagram showing a basic configuration example of an optical recording / reproducing apparatus. FIG. 2 is a diagram showing an example of a write strategy generated at the time of recording on an optical disc in the optical recording / reproducing apparatus. FIG. 2 further shows the reproduced waveform.

  FIG. 3 is a flowchart showing an example of a procedure from optical disc insertion to recording in the optical recording / reproducing method. 4 to 7 are flowcharts showing an example of the procedure for correcting the pulse width in the optical recording / reproducing method. 8 to 11 are diagrams showing examples of the width of the signal portion corresponding to the 2T space of the reproduction signal detected by the length of the front mark and the rear mark in the space width detection unit. 12 to 17 are diagrams showing the relationship between each pulse width and the difference in the width of the signal portion corresponding to the 2T space, and the relationship between the pulse width and the jitter value in the optical recording / reproducing method.

In FIG. 1, a semiconductor laser 110 as a laser light source is driven and controlled by a laser driving unit 120.
At the time of data reproduction, laser light emitted from the semiconductor laser 110 and having an output value (reproduction power) necessary for data reproduction is condensed on the optical disk 160 via the collimator lens 130, the beam splitter 140, and the objective lens 150. Irradiated. The reflected light from the optical disk 160 passes through the objective lens 150, is separated from incident light by the beam splitter 140, and is received by the light receiving element 180 through the detection lens 170.

  Among these, the semiconductor laser 110, the collimator lens 130, the beam splitter 140, the objective lens 150, and the detection lens 170 constitute an optical system. The optical system, the light receiving element 180, and the laser driving unit 120 An optical pickup PU is configured.

  The light receiving element 180 converts an optical signal into an electric signal. The electrical signal converted in the light receiving element 180 is input to the prepit detection unit 200, the asymmetry detection unit 210, and the equalizer 220 via the head amplifier 190. The prepit detection unit 200 detects information unique to the optical disc such as a recommended value of asymmetry α recorded in advance in the prepit portion of the optical disc 160 from the input electrical signal.

  In addition, the electrical signal from the head amplifier 190 input to the equalizer 220 is shaped, and the signal error rate is reduced by performing waveform equalization and maximum likelihood decoding in a PRML (Partial Response Maximum Likelihood) signal processing unit 260. Input to the data decoder 270. The jitter value detector 280 receives a signal shaped by the equalizer 220. The data decoder 270 generates (reproduces) data recorded on the optical disc 160 by binarizing the input electric signal and performing processing such as demodulation and error correction.

  The jitter value detection unit 280 detects a jitter value, which is an index obtained from the absolute value of the phase error between generated clocks, using a reproduction signal and a PLL (Phase Locked Loop) (not shown).

The asymmetry detection unit 210 performs AC (alternating current) coupling on the input electrical signal, and detects the peak level A1 and the bottom level A2 of the AC coupled electrical signal. The asymmetry value α is calculated from the detected peak level A1 and bottom level A2 using the following equation (1).
α = (A1 + A2) / 2 (A1-A2) (1)
Here, the peak level A1 and the bottom level A2 are generated in the portion where the longest space and the longest mark appear alternately, and these values are the peak level and the bottom level of the portion where the shortest space and the shortest mark appear alternately. Is expressed as a zero level.

  At the time of data recording, the data encoder 230 assigns an error correction code to the original data to be recorded, which is supplied from the central control unit 250, performs data modulation, and generates a basic drive signal to the semiconductor laser 110. Record data is generated. The laser waveform controller 240 generates a write strategy signal based on the recording data. That is, after the write strategy is set from the central control unit 250, when the recording data specifying the clock cycle number n, that is, the recording data specifying any of 2T to 9T, is given from the data encoder 230, the laser waveform The control unit 240 outputs a write strategy signal corresponding to such recording data (a signal generated in accordance with the write strategy and having a waveform substantially the same as the waveform of the light emission pulse train).

  The laser drive unit 120 drives the semiconductor laser 110 with a drive current corresponding to the generated write strategy signal. Laser light having an output value (recording power) necessary for data recording emitted from the semiconductor laser 110 is condensed and irradiated onto the optical disc 160 through the collimator lens 130, the beam splitter 140, and the objective lens 150. As a result, a mark is formed, and a recording portion including a mark and a space located between the marks is formed.

  2A to 2E show examples of write strategy signals generated by the laser waveform controller 240 in the optical recording / reproducing apparatus 100. FIG. FIG. 2A shows a channel clock (recording channel clock) having a period T used for recording. FIG. 2B shows an example of recording data including a mark part MA and a space part SA. FIG. 2C shows an example of a write strategy signal for recording the recording data of FIG. 2B, that is, a light emission pulse pattern. The light emission pulse pattern has a ternary power level, that is, a recording power level PW, an erasing power level PE, and a bias power level PBW, and is a recording pulse waveform modulated in a pulse shape. The width of the first pulse F is Ttop, and the shift amount (relative position) of the first pulse start end position when the position shifted to the right by 1T from the rising position of the mark portion MA of the recording data shown in FIG. The shift amount (relative position) of the erase pulse start end position when the width of the intermediate pulse (pulse other than the head pulse) M is TMP and the falling position of the mark portion MA of the recording data shown in FIG. Is represented by dTE.

  In the following description, the width of the last pulse L among the intermediate pulses (pulses other than the first pulse) M is referred to as TLP, and a pulse other than the last pulse L, that is, a pulse positioned between the first pulse F and the last pulse L. Is referred to as “intermediate pulse” M in the narrow sense. However, when the number of cycles n is 3, that is, the recording mark length is 3T, the write strategy signal has two pulses, a first pulse F and a last pulse L. The intermediate pulse M exists when the number of cycles n is 4 or more, that is, the recording mark length is 4T or more. When n is 4 or more, the number of intermediate pulses M is n-3.

  Here, the parameters relating to the pulse width (Ttop, TMP, TLP) and the position of the pulse (dTtop, dTE) must be individually corrected according to the recording mark length. When the mark length is 5T or more, the period number n is 4, that is, the same value as each parameter when the recording mark length is 4T. That is, the parameters of the write strategy to be corrected are the period number n is 2, that is, the recording mark length is 2T, the pulse width (Ttop) and the pulse position (dTtop, dTE), and the period number n is 3, that is, the recording mark Pulse width (Ttop, TLP) and pulse position (dTtop, dTE) when the length is 3T, period number n is 4, that is, pulse width (Ttop, TMP, TLP) and pulse length when the recording mark length is 4T There are 12 types of positions (dTtop, dTE).

FIG. 2D shows a mark MK on the optical disc formed by performing recording with the write strategy of FIG. 2C, and a space SP positioned between the marks MK. The horizontal axis of FIG. 2D is the length (position) along the track of the optical disk, but is shown corresponding to the light emission pulse pattern of FIG. 2C for convenience.
FIG. 2E shows a reproduction signal obtained by reading the mark MK and the space SP shown in FIG. This playback signal is a signal portion corresponding to the mark MK (sometimes referred to as “mark portion of the playback signal” or simply “mark portion”) MB and a signal portion corresponding to space SP (“playback signal It may be referred to as “space part” or simply “space part”).

The shortest mark has a length corresponding to the cycle number n = 2, that is, 2T, and the longest mark has a length corresponding to the cycle number n = 9, that is, 9T.
2 (b) and 2 (c) record the shortest mark, ie 2T mark, then the second shortest mark, ie 3T mark, and then the third shortest mark, ie 4T. This shows the case of recording the mark.

  As shown, the multi-pulse type write strategy signal consists of only a single pulse when the recording mark length is 2T, and includes a plurality of pulses when the recording mark length is 3T or more.

  A central control unit 250 in FIG. 1 controls the entire apparatus during reproduction and writing of the optical recording / reproducing apparatus 100, and includes prepit information from the prepit detection unit 200 and asymmetry values from the asymmetry detection unit 210. While receiving the reproduction data from the data decoder 270 and the jitter value from the jitter value detector 280, the control signal is given to the data encoder 230, the laser waveform controller 240, and the laser driver 120.

  The central control unit 250 also corrects the write strategy, which will be described later with reference to FIGS. 3 to 7, in particular, correction of the pulse width, calculation of the asymmetry value, and test writing performed using the corrected write strategy and asymmetry value. Control and so on.

The central control unit 250 includes, for example, a CPU 250a, a ROM 250b that stores a program for operating the CPU 250a, and a RAM 250c that stores data. The program stored in the ROM 250b includes a part defining a calculation for adjusting the pulse width described later with reference to FIGS. 4 to 7 and a correction of the pulse width described with reference to FIGS. Including. The ROM 250b also includes a coefficient for setting a pulse width change amount, a target difference amount between two space portions to be compared, and an allowable error amount for determining adjustment accuracy when correcting a pulse width described later. Etc., various constants are stored.

  Generally, the recording power is optimized by performing test writing before recording information. This procedure will be described below.

First, using a test pattern composed of 2T to 9T mark portions and space portions corresponding to random recording data, for example, test writing is performed on the optical disc 160 by changing the recording power. The recorded area on the optical disk 160 is reproduced, the asymmetry value is detected by the asymmetry detection unit 210, and the detected asymmetry value is compared with the target asymmetry value in the central control unit 250 to obtain the optimum recording power. .
In general, the asymmetry value increases as the recording power increases, and the asymmetry value decreases as the recording power decreases.

The central control unit 250 compares the detected values of asymmetry values corresponding to a plurality of different recording powers with the target value, and sets the recording power that produces the detected value closest to the target value as the optimum recording power.
Instead of doing this, trial writing to the optical disc 160 with one recording power is performed and playback is performed, an asymmetry value is detected from the playback result, and the detected asymmetry value is compared with the target asymmetry value. Then, the optimum value may be obtained by increasing or decreasing the recording power according to the comparison result.

  Based on such an optical recording method, in the present embodiment, the space SP detected by the space width detector 290 when the mark MK and the space SP formed by trial writing are read and the signal is reproduced. The width of the signal portion SB corresponding to is detected for each length of the mark MK located immediately before and after the space SP (the length of the reproduction signal portion MB corresponding to the mark MK expressed by the number of clock cycles). The pulse width is corrected based on the comparison result.

Hereinafter, the procedure of the optical recording method of the present embodiment will be described with reference to FIG.
When the optical disk 160 used for recording is first inserted into the optical recording / reproducing apparatus 100, this is detected by a sensor (not shown) (step S10) and transmitted to the central control unit 250. The pickup PU is driven to read disc-specific information such as a recommended write strategy value and a recommended asymmetry α value recorded in advance by the disc manufacturer from the optical disc 160 (step S11).

  Next, in step S12, the recommended value of the read write strategy is set in the central control unit 250 (for example, in the RAM 250c) as an initial write strategy for correcting the pulse width. The initial write strategy may be a specific write strategy preset in the optical recording / reproducing apparatus 100, instead of a value read from the optical disc 160. Instead, a write strategy determined by a value read from the optical disc 160 and a relational expression set in advance in the optical recording / reproducing apparatus 100 may be used as the initial write strategy.

  In step S13, the recommended value of the read asymmetry α value is set in the central control unit 250 (for example, in the RAM 250c) as a target value for use in optimizing the recording power. As a target value of the asymmetry α value, a specific value preset in the optical recording / reproducing apparatus 100 may be used instead of a value read from the optical disc 160. Alternatively, as a target value of the asymmetry α value, a value read from the optical disc 160 and a value determined by a relational expression preset in the optical recording / reproducing apparatus 100 may be used.

  Thereafter, when a recording instruction is given by means (not shown) (S14), trial writing to the optical disc 160 is performed in step S15 using the initial write strategy and asymmetry target value set as described above. That is, by setting the write strategy (strategy for each nT) set in the central control unit 250 in step S12 in the laser waveform control unit 240, the laser waveform control unit 240 generates a write strategy based on the test pattern. Then, trial writing on the optical disk 160 is performed using an optical pickup. Then, the area on the optical disc 160 in which the test pattern is recorded is reproduced by an optical pickup, and the asymmetry value detected by the asymmetry detection unit 210 and the asymmetry target value set in step S13 are compared by the central control unit 250, The optimum recording power is determined by performing control so as to match.

  Then, after performing this test writing and adjusting the power, the pulse width is corrected in step S16. In step S16, the power adjustment may be performed again together with the correction of the pulse width.

  Finally, in step S17, the laser waveform control unit 240 generates a write strategy based on the recording data by setting the pulse width corrected in step S16 to the laser waveform control unit 240, and the recording determined in step S15. The original writing (main writing) to the optical disc 160 is performed by the power. When the read power is readjusted in step S16, the value determined in step S16 may be used as the write power instead of the value determined in step S15.

  Among the above, the process of step S10 is performed by a sensor for detecting insertion of an optical disk (not shown) and the central control unit 250, and the process of step S11 is performed by the optical pickup PU, the head amplifier 190, the prepit detection unit 200, the equalizer. 220, the PRML signal processing unit 260, the data decoder 270, and the central control unit 250. The processes in steps S12 and S13 are performed by the central control unit 250, and the process in step S14 receives a recording instruction (not shown). Means (interface) and the central control unit 250, and the processing of steps S15 and S16 is performed by the head amplifier 190, the asymmetry detection unit 210, the central control unit 250, the laser waveform control unit 240, and the optical pickup PU. The process of step S17 is a central system. Part 250, data encoder 230 is performed by a laser waveform controller 240, and the optical pickup PU.

In step S16 of FIG. 3, the processes of FIGS. 4 to 7 are performed.
FIG. 4 is a diagram showing a procedure for correcting the width 2Ttop of the leading pulse F when the recording mark is 2T in the process of step S16 of FIG.
When this process is started (S160), in step S161, trial writing is performed on the optical disc 161 using the initial write strategy set in step S12 and the recording power determined in step S15. In step S162, The signal trial-written in step S161 is reproduced.

  The processing in step S161 is performed by the central control unit 250, the laser waveform control unit 240, and the optical pickup PU, and the processing in step S162 is performed by the optical pickup PU, the head amplifier 190, the equalizer 220, and the PRML signal processing unit 260. .

  Next, in step S163, the space width detector 290 reproduces the space width of the reproduced signal corresponding to the case where the space length of the recording data of the signal reproduced in step S162 is 2T (the signal portion SB corresponding to the space SP). Is detected for each mark length before and after the space.

Next, in step S164, the space width when the front mark is 3T to 9T and the rear mark is 2T is extracted from the space width detected in step S163, and the average value L2S (2Tt) is calculated.
Next, in step S165, the space width when both the front mark and the rear mark are 2T is extracted from the space width detected in step S163, and the average value L2S (2T) is calculated.
The reason why the space width is extracted in steps S164 and S165 will be described later with reference to FIG.
As the space width in steps S164 and S165, the average value of the space width when the trailing mark of the space is 2T is used, but the average value of the space width when the trailing mark is a specific nT other than 2T is used. May be. In this case, the post mark length of the space extracted in step S164 and the post mark length of the space extracted in step S165 must be equal. (That is, n in step S164 and n in step S165 must be equal to each other.) This will also be described later with reference to FIG.

  Next, in step S166, the space width L2S (2Tt) when the previous mark extracted in step S164 is 3T to 9T and the rear mark is 2T, and the previous mark and rear mark extracted in step S165 are both 2T. The difference amount DL2S (2T) is calculated from the space width L2S (2T).

Next, in step S167, the difference amount DL2S (2T) calculated in step S166 is compared with a preset allowable range. If the difference amount DL2S (2T) is within the allowable range, the pulse width (2Ttop) ) Is finished (S171).
If the difference DL2S (2T) is outside the allowable range, the process of step S168 is performed.

In step S168, the difference amount DL2S (2T) is compared with a preset target difference amount TH (2T) to determine which is larger.
If the difference amount DL2S (2T) is larger than the target difference amount TH (2T), the write strategy pulse width (width of the pulse F when the recording mark is 2T) 2Ttop is increased in step S169. Correct it.
On the other hand, when the difference amount DL2S (2T) is smaller than the target difference amount TH (2T), in step S170, the pulse width 2Ttop is corrected so as to decrease.

Here, the correction of the pulse width 2Ttop is obtained in advance by calculating the change amount of the pulse width 2Ttop with respect to the difference amount DL2S (2T), and the change width of the pulse width 2Ttop is set according to the obtained difference amount DL2S (2T). It may be determined and corrected, or may be corrected using a minimum value that can be changed by the laser control unit 240.
The processes in steps S164 to S170 are performed by the central control unit 250.

In step S169 and S170, after the pulse width 2Ttop is corrected, using the corrected pulse width 2Ttop, trial writing is performed again in step S161, and the subsequent operation is performed with the difference amount DL2S (2T) in step S167. The correction of the pulse width 2Ttop is repeated until the allowable range is reached.
Note that the recording power may be adjusted again before trial writing in step S161.

FIG. 5 is a diagram showing a procedure for correcting the width mTtop of the leading pulse F when the recording mark is mT (m = 3, 4) in the process of step S16 of FIG.
When this process is started (S172), trial writing is performed on the optical disc 160 in step S161.
The processing in steps S161 to S163 is the same as that shown in FIG. 4, and detailed description thereof is omitted.

In step S173, based on the space width detected in step S163, the previous mark is a specific nT of 2T to 9T (the previous mark is nT (n is an arbitrary one of 2 to 9, for example, predetermined). The information indicating that is stored in, for example, the ROM 250b), the space width when the rear mark is 2T is extracted, and the average value L2S (mTt) is calculated.
Next, in step S174, from the space width detected in step S163, the space width in the case where the preceding mark is 2T to 9T and the above-mentioned specific nT and the rear mark is mT is extracted, and the average value thereof is extracted. L2S (mT) is calculated.
Note that the previous mark length of the space extracted in step S173 and the previous mark length of the space extracted in step S174 must be equal. (That is, n in step S173 and n in step S174 are equal to each other.) The reason will be described later with reference to FIG. The reason why the space width is extracted in steps S173 and S174 will be described later with reference to FIG.

  Next, in step S175, the space width L2S (mTt) in the case where the previous mark extracted in step S173 is the specific nT of 2T to 9T and the rear mark is 2T, and the previous mark extracted in step S174. The difference DL2S (mT) is calculated from the above-mentioned specific nT of 2T to 9T and the space width L2S (mT) when the rear mark is mT.

Next, in step S176, the difference amount DL2S (mT) calculated in step S175 is compared with a preset allowable range. If the difference amount DL2S (mT) is within the allowable range, the pulse width (mTtop) ) Is finished (S180).
If the difference DL2S (mT) is outside the allowable range, the process of step S177 is performed.

In step S177, the difference amount DL2S (mT) is compared with a preset target difference amount TH (mT) to determine which is larger.
If the difference amount DL2S (mT) is larger than the target difference amount TH (mT), in step S178, the write strategy pulse width (width of the leading pulse F when the recording mark is mT) mTtop is increased. To correct.
On the other hand, when the difference amount DL2S (mT) is smaller than the target difference amount TH (mT), in step S179, the pulse width mTtop is corrected so as to decrease.

  Here, the comparison between the difference amount DL2S (mT) and the target difference amount TH (mT) in step S177 and the correction of the pulse width mTtop in steps S178 and S179 are performed according to the size of the number of periods m representing the pulse width. It is only necessary to perform m for the difference amount DL2S (mT) determined to be outside the allowable range in S176. For example, if it is determined in step S176 that the difference amount DL2S (3T) when m = 3 is outside the allowable range, and the difference amount DL2S (4T) when m = 4 is determined to be within the allowable range, in step S177. Only compares the difference amount DL2S (3T) when m = 3 and the target difference amount TH (3T) when m = 3. In steps S178 and S179, the head pulse width 3Ttop when m = 3 is set. Correct it.

Here, the correction of the pulse width mTtop is obtained in advance by calculating the amount of change of the pulse width mTtop with respect to the difference amount DL2S (mT), and the amount of change of the pulse width mTtop is determined according to the obtained difference amount DL2S (mT). It may be determined and corrected, or may be corrected using a minimum value that can be changed by the laser control unit 240.
The processes in steps S173 to S179 are performed by the central control unit 250.

In step S178 and S179, after the pulse width mTtop is corrected, using the corrected pulse width mTtop, test writing is performed again in step S161, and the subsequent operation is performed in step S176 where the difference amount DL2S (mT) is calculated. The correction of the pulse width mTtop is repeated until it falls within the allowable range.
Note that the recording power may be adjusted again before trial writing in step S161.

FIG. 6 is a diagram showing a procedure for correcting the width pTLP of the final pulse L when the recording mark is pT (p = 3, 4) in the process of step S16 of FIG.
When this process is started (S181), trial writing is performed on the optical disc 160 in step S161.
The processing in steps S161 to S163 is the same as that shown in FIG. 4, and detailed description thereof is omitted.

In step S182, based on the space width detected in step S163, the front mark is 2T and the rear mark is a specific nT of 2T to 9T (the rear mark is nT (n is an arbitrary one of 2 to 9). For example, the space width in the case of predetermined information stored in the ROM 250b is extracted, and the average value L2S (pLt) is calculated.
Next, in step S183, the space width when the preceding mark is pT and the following mark is the above-mentioned specific nT out of 2T to 9T is extracted from the space width detected in step S163, and the average value L2S is extracted. (PL) is calculated.
The post mark length of the space extracted in step S182 and the post mark length of the space extracted in step S183 must be equal. (That is, n in step S182 and n in step S183 are equal to each other.) The reason will be described later with reference to FIG. The reason why the space width is extracted in steps S182 and S183 will be described later with reference to FIG.

  Next, in step S184, the space width L2S (pLt) in the case where the previous mark extracted in step S182 is 2T and the subsequent mark is the above specific nT among 2T to 9T, and the previous mark extracted in step S183. Is the difference amount DL2S (pL) from the space width L2S (pL) in the case of the above-mentioned specific nT of 2T to 9T.

Next, in step S185, the difference amount DL2S (pL) calculated in step S184 is compared with a preset allowable range. If the difference amount DL2S (pL) is within the allowable range, the pulse width (pTLP) ) Is finished (S189).
If the difference DL2S (pL) is outside the allowable range, the process of step S186 is performed.

In step S186, the difference amount DL2S (pL) is compared with a preset target difference amount TH (pL) to determine which is larger.
If the difference amount DL2S (pL) is larger than the target difference amount TH (pL), the write strategy pulse width (width of the final pulse L when the recording mark is pT) pTLP is increased in step S187. To correct.
On the other hand, when the difference amount DL2S (pL) is smaller than the target difference amount TH (pL), in step S188, the pulse width pTLP is corrected so as to decrease.

  Here, the comparison between the difference amount DL2S (pL) and the target difference amount TH (pL) in step S186 and the correction of the pulse width pTLP in steps S187 and S188 are performed according to the magnitude of the number of periods p representing the pulse width. It is only necessary to perform p for which the difference amount DL2S (pL) is determined to be outside the allowable range in S185. For example, if it is determined in step S185 that the difference DL2S (3L) when p = 3 is outside the allowable range, and the difference DL2S (4L) when p = 4 is determined to be within the allowable range, in step S186. Only compares the difference amount DL2S (3L) when p = 3 and the target difference amount TH (3L) when p = 3. In steps S187 and S188, the final pulse width 3TLP when p = 3 is obtained. Correct it.

Here, the correction of the pulse width pTLP is performed in advance by obtaining a change amount of the pulse width pTLP with respect to the difference amount DL2S (pL), and changing the change amount of the pulse width pTLP according to the obtained difference amount DL2S (pL). It may be determined and corrected, or may be corrected using a minimum value that can be changed by the laser control unit 240.
The processes in steps S182 to S188 are performed by the central control unit 250.

After the pulse width pTLP has been corrected in steps S187 and S188, test writing is performed again in step S161 using the corrected pulse width pTLP, and the subsequent operation in step S185 is performed with the difference amount DL2S (pL). The pulse width pTLP is repeatedly corrected until it falls within the allowable range.
Note that the recording power may be adjusted again before trial writing in step S161.

FIG. 7 is a diagram showing a procedure for correcting the width kTMP of the intermediate pulse M when the recording mark is kT (k ≧ 4) in the process of step S16 of FIG.
When this process is started (S190), trial writing is performed on the optical disc 160 in step S161. Steps S161 to S163 are the same as those shown in FIG.

In step S191, based on the space width detected in step S163, the front mark is 4T and the rear mark is a specific nT of 2T to 9T (the rear mark is nT (n is an arbitrary one of 2 to 9). For example, the space width in the case of predetermined information stored in the ROM 250b is extracted, and the average value L2S (kM4) is calculated.
Next, in step S192, from the space width detected in step S163, the space when the front mark is sT (s is any value of 5 or more) and the rear mark is the above-mentioned specific nT out of 2T to 9T. The width is extracted, and the average value L2S (kMs) is calculated.
Note that the post mark length of the space extracted in step S191 and the post mark length of the space extracted in step S192 must be equal. (That is, n in step S191 and n in step S192 must be equal to each other.) This reason will be described later with reference to FIG. The reason why the space width is extracted in steps S191 and S192 will be described later with reference to FIG.

  In step S192, as the space width when the previous mark of the space is sT, the average value of the space widths in all cases where the previous mark is 5T or more is used, but the specific nT whose previous mark is 5T or more is used. Or the average value of a plurality of cases where the length of the previous mark is 5T or more (in the case of a plurality of nT values) may be used.

  Next, in step S193, the space width L2S (kM4) in the case where the previous mark extracted in step S191 is 4T and the rear mark is the above specific nT among 2T to 9T, and the previous mark extracted in step S192. Is calculated from the space width L2S (kMs) in the case of sT and the rear mark is the above-mentioned specific nT of 2T to 9T.

Next, in step S194, the difference amount DL2S (kM) calculated in step S193 is compared with a preset allowable range. If the difference amount DL2S (kM) is within the allowable range, the pulse width (kTMP) ) Is finished (S198).
If the difference DL2S (kM) is outside the allowable range, the process of step S195 is performed.

In step S195, the difference amount DL2S (kM) is compared with a preset target difference amount TH (kM) to determine which is larger.
If the difference amount DL2S (kM) is larger than the target difference amount TH (kM), the write strategy pulse width (width of the intermediate pulse M when the recording mark is kT) kTMP is increased in step S196. To correct.
On the other hand, when the difference amount DL2S (kM) is smaller than the target difference amount TH (kM), the pulse width kTMP is corrected to decrease in step S197.

Here, the correction of the pulse width kTMP is performed in advance by obtaining a change amount of the pulse width kTMP with respect to the difference amount DL2S (kM), and changing the change amount of the pulse width kTMP according to the obtained difference amount DL2S (kM). It may be determined and corrected, or may be corrected using a minimum value that can be changed by the laser control unit 240.
The processing in steps S191 to S197 is performed by the central control unit 250.

After the pulse width kTMP has been corrected in steps S196 and S197, test writing is performed again in step S161 using the corrected pulse width kTMP, and the subsequent operation is performed with the difference amount DL2S (kM) in step S194. The pulse width kTMP is repeatedly corrected until it falls within the allowable range.
Note that the recording power may be adjusted again before trial writing in step S161.

  As described above, the case where the process of FIGS. 4 to 7 is automatically performed at the start of the recording operation of the optical disk apparatus as step S16 of the process of FIG. 3 has been described. It may be performed by an engineer. In that case, the development engineer gives an instruction to start processing by manual input (such as a tool for correcting the pulse width), and the processing of FIGS. 4 to 7 is started accordingly.

  In the correction of the pulse width in FIGS. 4 to 7, a limit value of the number of corrections of each pulse width is set in advance, and when the number of corrections of the pulse width exceeds the limit value, the correction of the pulse width is performed. You may make it complete | finish.

  In addition, the correction of the width mTtop of the first pulse F when the recording mark is mT (m = 3, 4) and the width pTLP of the last pulse L when the recording mark is pT (p = 3, 4) This must be done after optimally correcting the width 2Ttop of the pulse F in the case of 2T. The reason will be described later with reference to FIGS.

  8 (a) to 11 (j) show the write strategy signal pulse width and the recorded signal used in the optical recording / reproducing apparatus 100 shown in FIG. The waveform of the reproduction signal obtained by reproduction is shown. In any case, the space length of the recording data is 2T, and one of the marks before and after the mark is different from each other.

8A to 8E show the case where both the front mark and the rear mark are 2T, and FIGS. 8F to 8J show the case where the front mark is 3T to 9T and the rear mark is 2T. And
FIGS. 9A to 9E show a case where the front mark is a specific nT of 2T to 9T, and the rear mark is mT.
FIGS. 9F to 9J show a case where the front mark is a specific nT of 2T to 9T and the rear mark is 2T.
FIGS. 10A to 10E show a specific nT in which the front mark is pT and the back mark is 2T to 9T.
FIGS. 10F to 10J show a specific nT in which the front mark is 2T and the back mark is 2T to 9T.
FIGS. 11A to 11E show a specific nT in which the front mark is 4T and the back mark is 2T to 9T.
FIGS. 11F to 11J show a specific nT in which the front mark is sT or more and the back mark is 2T to 9T.

  8 (a), FIG. 8 (f), FIG. 9 (a), FIG. 9 (f), FIG. 10 (a), FIG. 10 (f), FIG. 11 (a) and FIG. Recording data consisting of a part MA and a space part SA is shown. 8 (b) to (d) and FIGS. 8 (g) to (i), FIGS. 9 (b) to (d), FIGS. 9 (g) to (i), and FIGS. 10 (b) to (d). ) And FIGS. 10 (g) to (i), FIGS. 11 (b) to (d) and FIGS. 10 (g) to (i), FIG. 8 (a), FIG. 8 (f), and FIG. 9 (a). 9 (f), FIG. 10 (a), FIG. 10 (f), FIG. 11 (a), and FIG. 11 (f) show write strategies for recording the recording data.

FIG. 8B and FIG. 8G show the case of the optimal 2T pulse width 2Ttop (1) (when the write strategy pulse width 2Ttop is optimal), and FIG. FIG. 8 (h) shows the case of a pulse width 2Ttop (2) larger than 2Ttop (1), and FIGS. 8 (d) and 8 (i) show a smaller width than 2Ttop (1). In this case, the pulse width is 2Ttop (3).
FIGS. 9B and 9G show the case of the optimum mT start pulse width mTtop (1) (when the write strategy start pulse width mTtop is optimum), and FIG. 9C and FIG. FIG. 9 (h) shows the case of a pulse width mTtop (2) larger than mTtop (1), and FIGS. 9 (d) and 9 (i) show a smaller width than mTtop (1). In this case, the pulse width mTtop (3) is shown.
FIG. 10B and FIG. 10G show the case of the final pulse width pTLP (1) of the optimum pT (when the final pulse width pTLP of the write strategy is optimum). FIG. 10 (h) shows the case of the pulse width pTLP (2) larger than the above pTLP (1), and FIG. 10 (d) and FIG. 10 (i) show a case where the pulse width is smaller than the above pTLP (1). This shows the case of the pulse width pTLP (3).
FIG. 11B and FIG. 11G show the case of the optimum intermediate pulse width kTMP (1) of kT (when the intermediate pulse width kTMP of the write strategy is optimum), and FIG. FIG. 11 (h) shows a case where the pulse width kTMP (2) is larger than that of the kTMP (1). FIGS. 11 (d) and 11 (i) show a case where the pulse width is smaller than the kTMP (1). The case of the pulse width kTMP (3) is shown.

  8 (e) and 8 (j), FIG. 9 (e) and FIG. 9 (j), FIG. 10 (e) and FIG. 10 (j), FIG. 11 (e) and FIG. 8 (b) to (d) and FIGS. 8 (g) to (i), FIG. 9 (b) to (d), FIG. 9 (g) to (i), FIG. 10 (b) to (d), and FIG. 10 (g) to (i), marks (b) to (d) and marks on the optical disk formed by performing recording with the write strategy of FIGS. The reproduction signal obtained by reading out the positioned space is shown.

As shown in FIG. 8B, when the pulse width in the case of 2T is an optimum value (2Ttop (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. As shown in curve RD2T (1) in e).
As shown in FIG. 8C, when recording is performed with a pulse width 2Ttop (2) larger than the 2Ttop (1), as shown by a curve RD2T (2) in FIG. The previous mark portion MB is larger than that recorded at 2Ttop (1), and the width of the immediately following 2T space portion SB is reduced due to the influence.
On the other hand, as shown in FIG. 8D, when recording with a pulse width 2Ttop (3) smaller than 2Ttop (1), as shown by a curve RD2T (3) in FIG. The previous mark portion MB of the reproduction signal is smaller than that recorded in 2Ttop (1), and the width of the immediately subsequent 2T space portion SB is increased due to the influence.

  On the other hand, as shown in FIGS. 8F to 8J, when the front mark is 3T to 9T and the rear mark is 2T, the width of the 2T space portion SB slightly changes, but the change This is not significant compared to the change in the width of the 2T space portion SB when the front mark and the rear mark are both 2T, as shown in FIGS. As shown in FIG. 8G, when the pulse width in the case of 2T is an optimum value (2Ttop (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. j) as shown by the curve RD2Tt (1).

  As shown in FIG. 8 (h), when recording is performed with a pulse width 2Ttop (2) larger than 2Ttop (1), as shown by a curve RD2Tt (2) in FIG. The rear mark portion MB is larger than that recorded at 2Ttop (1), but the trailing position of the mark portion MB is almost the same, so that the width of the immediately preceding 2T space portion SB is greatly affected. Don't give.

  Similarly, as shown in FIG. 8 (i), when recording with a pulse width 2Ttop (3) smaller than 2Ttop (1), as shown by a curve RD2Tt (3) in FIG. 8 (j), Although the mark portion MB after the reproduction signal is smaller than that recorded at 2Ttop (1), the trailing edge position of the mark portion MB is almost the same, so that the width of the immediately preceding 2T space portion SB is Does not affect much.

  Here, in FIGS. 8A to 8D and FIGS. 8F to 8I, the case where both rear marks are 2T is shown, but a specific nT other than 2T may be used. In this case, however, the previous mark length in FIGS. 8A to 8D and the previous mark length in FIGS. 8F to 8I must be equal. For example, if the previous mark is 2T as shown in FIG. 8, even if the pulse width 2Ttop in the case of 2T changes, the width of the space portion SB immediately before the mark in FIG. Since the amount of change in the width L2S (2Tt) of the space portion SB immediately before the mark in FIG. 8J is the same in L2S (2T), the difference between L2S (2T) and L2S (2Tt) is This is because it does not change. If the two previous mark lengths are different, it is difficult to optimally correct 2Ttop because the influence on the pulse width other than 2Ttop must be taken into consideration.

  As described above, based on the width of the 2T space signal when the front mark is 3T to 9T and the rear mark is a specific nT of 2T to 9T, 2T when the front mark is 2T and the rear mark is a specific nT of 2T to 9T 2Ttop can be optimally corrected by the difference from the width of the space portion.

As shown in FIG. 9B, when the leading pulse width of mT is an optimum value (mTtop (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. ) As shown by the curve RDmT (1).
As shown in FIG. 9C, when recording is performed with a pulse width mTtop (2) larger than the above mTtop (1), as shown by a curve RDmT (2) in FIG. The rear mark portion MB is larger than that recorded by the mTtop (1), and the width of the immediately preceding 2T space portion SB becomes smaller due to the influence.
Conversely, as shown in FIG. 9 (d), when recorded with a pulse width mTtop (3) smaller than the mTtop (1), as shown by the curve RDmT (3) in FIG. 9 (e), The rear mark portion MB of the reproduction signal is smaller than that recorded by the mTtop (1), and the width of the immediately preceding 2T space portion SB is increased due to the influence.

  In contrast, as shown in FIGS. 9F to 9J, when the front mark is a specific nT of 2T to 9T and the rear mark is 2T, the width of the 2T space portion SB does not change. . As shown in FIG. 9 (g), when the head pulse width of mT is an optimum value (mTtop (1)), the reproduction signal composed of the space portion SB and the preceding and following mark portions MB is shown in FIG. ) As shown by the curve RDmTt (1).

  As shown in FIG. 9 (h), when recording is performed with a pulse width mTtop (2) larger than the above mTtop (1), as shown by a curve RDmTt (2) in FIG. The previous mark portion MB is larger than that recorded by the above mTtop (1), but the rising position of the immediately preceding 2T space portion SB is the same, so that there is no effect on the width of the immediately preceding 2T space portion SB. Not give.

  Similarly, as shown in FIG. 9 (i), when recorded with a pulse width mTtop (3) smaller than the above mTtop (1), as shown by a curve RDmTt (3) in FIG. 9 (j), The previous mark portion MB of the reproduction signal is smaller than that recorded in the mTtop (1), but the rising position of the immediately preceding 2T space portion SB is the same, so that the width of the immediately preceding 2T space portion SB is set. Has no effect.

  Here, the previous mark length in FIGS. 9A to 9D and the previous mark length in FIGS. 9F to 9I must be equal. For example, if both the previous marks are 2T, even if the pulse width 2Ttop in the case of 2T changes, the width L2S (mT) of the space portion SB immediately after the mark in FIG. This is because the difference between the width L2S (mTt) of the space portion SB immediately after the mark in 9 (j) is the same, and the difference between the L2S (mT) and L2S (mTt) does not change. If the previous mark lengths are different from each other, it is difficult to optimally correct mTtop because the influence on the pulse width other than mTtop must be taken into consideration.

  As described above, based on the width of the 2T space portion when the front mark is 2T to 9T and the back mark is 2T, the 2T space portion when the front mark is 2T to 9T and the rear mark is mT MTtop can be optimally corrected based on the difference from the width of.

  When the pulse width 2Ttop in the case of 2T is changed, the width of the 2T space portion in FIG. 9E is not affected by the rear mark, but the width of the 2T space portion in FIG. As in the case of 8 (j), since it is somewhat affected by the rear mark, the width of the 2T space portion when the front mark is 2T to 9T, the rear mark is mT, and the front mark is 2T to 9T. The difference from the width of the 2T space portion when the specific nT and the rear mark is 2T changes. Therefore, in order to optimally correct mTtop, first, the pulse width 2Ttop in the case of 2T must be optimally corrected.

  As shown in FIG. 10B, when the final pulse width of pT is an optimum value (pTLP (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. ) As shown by the curve RDpL (1).

  As shown in FIG. 10 (c), when recording is performed with a pulse width pTLP (2) larger than the above pTLP (1), as shown by a curve RDpL (2) in FIG. The previous mark portion MB is larger than that recorded by the pTLP (1), and the width of the immediately following 2T space portion SB is reduced due to the influence.

  Conversely, as shown in FIG. 10 (d), when recorded with a pulse width pTLP (3) smaller than the pTLP (1), as shown by a curve RDpL (3) in FIG. 10 (e), The previous mark portion MB of the reproduction signal is smaller than that recorded by the pTLP (1), and the width of the immediately following 2T space portion SB is increased due to the influence.

  On the other hand, as shown in FIGS. 10 (f) to 10 (j), when the front mark is 2T and the rear mark is 2T to 9T, the width of the 2T space portion SB does not change. . As shown in FIG. 10 (g), when the final pulse width of pT is an optimum value (pTLP (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. ) As shown by the curve RDpLt (1).

  As shown in FIG. 10 (h), when recorded with a pulse width pTLP (2) larger than the above pTLP (1), as shown by a curve RDpLt (2) in FIG. The rear mark portion MB is larger than that recorded by the pTLP (1), but since the trailing position of the mark portion MB is the same, the width of the immediately preceding 2T space portion SB is affected. Absent.

  Similarly, as shown in FIG. 10 (i), when recorded with a pulse width pTLP (3) smaller than the pTLP (1), as shown by a curve RDpLt (3) in FIG. 10 (j), The post-mark portion MB of the reproduction signal is smaller than that recorded in the pTLP (1), but since the trailing position of the mark portion MB is the same, the width of the immediately preceding 2T space portion SB is It has no effect.

  Here, the rear mark length in FIGS. 10A to 10D and the rear mark length in FIGS. 10F to 10I must be equal. For example, if both the rear marks are 3T, even if the 3T head pulse width 3Ttop changes, the width L2S (nL) of the space portion SB immediately before the mark in FIG. This is because, in (j), the amount of change in the width L2S (nLt) of the space portion SB immediately before the mark is the same, so the difference between the L2S (nL) and L2S (nLt) does not change. If the post-mark lengths of the two are different, it is difficult to optimally correct the pTLP because the influence on the pulse width other than the pTLP must be taken into consideration.

  The 2T space portion when the front mark is pT and the back mark is a specific nT of 2T to 9T based on the width of the 2T space portion when the front mark is 2T and the rear mark is a specific nT of 2T to 9T. The pTLP can be optimally corrected by the difference from the width of.

  When the pulse width 2Ttop in the case of 2T is changed, the width of the 2T space portion in FIG. 10 (e) is affected by the previous mark as in FIG. 8 (e), and in FIG. 10 (j). The width of the 2T space portion is not affected by the previous mark as in the case of FIG. 8 (j). Therefore, the 2T space portion in the case where the front mark is pT and the rear mark has a specific value of 2T to 9T. The difference between the width and the width of the 2T space portion in the case where the front mark is 2T and the rear mark is a specific nT of 2T to 9T varies. Therefore, in order to optimally correct pTLP, the pulse width 2Ttop in the case of 2T must first be optimally corrected as in the case of correction of mTtop.

  As shown in FIG. 11 (b), when the intermediate pulse width of kT is an optimum value (kTMP (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. ) As shown by the curve RDkM4 (1).

  As shown in FIG. 11 (c), when recorded with a pulse width kTMP (2) larger than the kTMP (1), as shown by a curve RDkM4 (2) in FIG. The previous mark portion MB is larger than that recorded by the kTMP (1), and as a result, the width of the immediately subsequent 2T space portion SB is reduced.

  Conversely, as shown in FIG. 11 (d), when recorded with a pulse width kTMP (3) smaller than the kTMP (1), as shown by a curve RDkM4 (3) in FIG. 11 (e), The previous mark portion MB of the reproduction signal is smaller than that recorded by the kTMP (1), and the width of the immediately following 2T space portion SB is increased due to the influence.

  On the other hand, as shown in FIGS. 11 (f) to 11 (j), the change in the width of the 2T space portion SB in the case where the front mark is sT and the back mark is 2T to 9T in a specific nT is shown in FIG. It becomes more prominent than the change in the width of the 2T space portion SB shown in (e). As shown in FIG. 11 (g), when the intermediate pulse width of kT is an optimum value (kTMP (1)), the reproduction signal composed of the space portion SB and the front and rear mark portions MB is shown in FIG. ) As shown by the curve RDkMs (1).

  As shown in FIG. 11 (h), when recorded with a pulse width kTMP (2) larger than the kTMP (1), as shown by a curve RDkMs (2) in FIG. The previous mark portion MB is larger than that recorded by the pTLP (1), and the width of the immediately following 2T space portion SB is reduced due to the influence. In this case, unlike FIGS. 11B to 11E, the number of intermediate pulses is not one, but a plurality of intermediate pulses, so that the change is more remarkable than the change in the curve RDkM4 (2) shown in FIG.

  Conversely, as shown in FIG. 11 (i), when recorded with a pulse width kTMP (3) smaller than kTMP (1), as shown by curve RDkMs (3) in FIG. The previous mark portion MB of the reproduction signal is smaller than that recorded by the kTMP (1), and the width of the immediately following 2T space portion SB is increased due to the influence. In this case, the curve RDkMs (2) shown in FIG. 11 (j) becomes more prominent than the change in the curve RDkM4 (2) shown in FIG. 11 (e). The change in (3) becomes more prominent than the change in the curve RDkM4 (3) shown in FIG.

  Here, the rear mark length in FIGS. 11A to 11D and the rear mark length in FIGS. 11F to 11I must be equal. For example, if both the rear marks are 3T, even if the 3T head pulse width 3Ttop changes, the width L2S (kM4) of the space portion SB immediately before the mark in FIG. This is because the difference between the width L2S (kMs) of the space portion SB immediately before the mark in (j) is the same, and therefore the difference between the L2S (kM4) and L2S (kMs) does not change. If the rear mark lengths of the two are different, it is difficult to optimally correct kTMP because the influence on the pulse width other than kTMP must be taken into consideration.

  The width of the 2T space portion when the front mark is 4T and the back mark is a specific nT of 2T to 9T and the width of the 2T space portion when the front mark is a sT and the back mark is a specific nT of 2T to 9T Therefore, kTMP can be optimally corrected.

  In order to examine the relationship between each pulse width and the difference between the widths of the 2T space portion, and the relationship between each pulse width and a jitter value that is an index of recording quality, An experiment was performed to obtain the difference amount and jitter value of the width of the 2T space portion when the pulse width was changed. Then, the relationship between the pulse width that minimizes the jitter value and the difference between the widths of the space portions was obtained.

  12 shows the reproduction jitter value (◯ mark) when the pulse width 2Ttop in the case of 2T is changed by three steps in the + direction and the − direction, and the difference amount DL2S (2T) (Δ mark) calculated in step S166 in FIG. FIG. 13 shows a reproduction jitter value (◯ mark) when the 3T head pulse width 3Ttop is changed by 3 steps in the + direction and the − direction, and the difference amount DL2S (step S175 in FIG. 5). 3T) (Δ mark), FIG. 14 shows the reproduction jitter value (◯ mark) when the 4T top pulse width 4Ttop is changed by 3 steps in the + direction and the − direction, and the calculation in step S175 in FIG. FIG. 15 shows the reproduction jitter value (◯ mark) when the 3T final pulse width 3TLP is changed by 3 steps in the + direction and the − direction, and FIG. FIG. 16 shows the difference amount DL2S (3L) (Δ mark) calculated in step S184, and FIG. 16 shows the reproduction jitter value (◯ mark) when the 4T final pulse width 4TLP is changed by 3 steps in the + direction and the − direction. 6 and the difference amount DL2S (4L) (Δ mark) calculated in step S184 of FIG. 6 shows the reproduction jitter when the intermediate pulse width kTMP of kT is changed by three steps in the + direction and the − direction. The value (◯ mark) and the difference amount DL2S (kM) (Δ mark) calculated in step S193 in FIG. 7 are shown. FIG. 17 shows the result when s = 5. That is, the DL2S (kM) in the figure is the space width L2S (kM4) when the previous mark extracted in step S191 is a specific nT of 4T and the rear mark is 2T to 9T, and the previous mark extracted in step S192. Is a difference from the space width L2S (kM5) in the case where the specific mark is 5T and the rear mark is 2T to 9T.

  From FIG. 12, the relationship between the pulse width 2Ttop and the difference DL2S (2T) in the case of 2T can be approximately linearly approximated. The value of the difference amount DL2S (2T) when 2Ttop is optimal, that is, when the jitter value is minimum, is about −0.13. Therefore, it can be seen that when 2Ttop is optimally corrected, 2Ttop should be corrected so that the difference DL2S (2T) is about −0.13. At this time, the value of the target difference amount TH (2T) in step S168 in FIG. 4 is −0.13. Further, since the relationship between 2Ttop and the difference amount DL2S (2T) can be approximately linearly approximated, the correction amount of 2Ttop can be known from the slope of the approximate line and the difference amount DL2S (2T). Further, it is understood that 2Ttop is increased when the difference amount DL2S (2T) is larger than −0.13, and 2Ttop is decreased when the difference amount DL2S (2T) is smaller than −0.13. .

  Here, as shown in step S167 of FIG. 4, the difference amount DL2S (2T) does not need to be set to just −0.13, and may be within a certain allowable range. In this case, the allowable range is set such that the jitter value deterioration amount from the optimum jitter value is about 0.5% at the maximum. Therefore, the allowable range in this case is −0.13 ± 0.04. Even when correcting a pulse width other than 2Ttop later, by using 0.04 as an allowable value of the deviation amount from the target difference amount, when correcting all the pulse widths, the jitter value deterioration amount can be reduced. It can be suppressed to 0.5% or less. This will be described later with reference to FIGS.

  From FIG. 13, the relationship between the 3T head pulse width 3Ttop and the difference DL2S (3T) can be approximately linearly approximated. Further, the difference DL2S (3T) is about 0.21 when 3Ttop is optimal, that is, when the jitter value is minimum. Therefore, it can be seen that when 3Ttop is optimally corrected, 3Ttop should be corrected so that the difference DL2S (3T) is about 0.21. At this time, the value of the target difference amount TH (3T) in step S177 in FIG. 5 is 0.21. Further, since the relationship between 3Ttop and the difference amount DL2S (3T) can be approximately linearly approximated, the correction amount of 3Ttop can be known from the slope of the approximate line and the difference amount DL2S (3T). Further, it is understood that 3Ttop is increased when the difference amount DL2S (3T) is larger than 0.21, and 3Ttop is decreased when the difference amount DL2S (3T) is smaller than 0.21.

  Here, as shown in step S176 of FIG. 5, the difference DL2S (3T) does not need to be exactly 0.21, but is 0.21 ± 0.04 as in the case of 2Ttop correction. Good. At this time, the maximum deterioration amount of the jitter value can be suppressed to only about 0.5%.

  From FIG. 14, the relationship between the 4T head pulse width 4Ttop and the difference DL2S (4T) can be approximately linearly approximated. The value of the difference amount DL2S (4T) when 4Ttop is optimal, that is, when the jitter value is minimum, is about 0.04. Therefore, it can be seen that when 4Ttop is optimally corrected, 4Ttop should be corrected so that the difference DL2S (4T) is about 0.04. At this time, the value of the target difference amount TH (4T) in step S177 in FIG. 5 is 0.04. Further, since the relationship between 4Ttop and the difference amount DL2S (4T) can be approximately linearly approximated, the correction amount of 4Ttop can be known from the slope of the approximate line and the difference amount DL2S (4T). Further, it is understood that 4Ttop is increased when the difference amount DL2S (4T) is greater than 0.04, and 4Ttop is decreased when the difference amount DL2S (4T) is less than 0.04.

  Here, as shown in step S176 of FIG. 5, the difference amount DL2S (4T) does not need to be set to just 0.04, and if it is between 0.04 ± 0.04 as in the case of 2Ttop correction. Good. At this time, the maximum deterioration amount of the jitter value can be suppressed to only about 0.5%.

  From FIG. 15, the relationship between the final pulse width 3TLP of 3T and the difference amount DL2S (3L) can be approximately linearly approximated. In addition, when 3TLP is optimal, that is, when the jitter value is minimum, the value of the difference amount DL2S (3L) is about 0.18. Therefore, it can be seen that when 3TLP is optimally corrected, 3TLP should be corrected so that the difference DL2S (3L) is about 0.18. At this time, the value of the target difference amount TH (3L) in step S186 in FIG. 6 is 0.18. Further, since the relationship between 3TLP and the difference amount DL2S (3L) can be approximately linearly approximated, the correction amount of 3TLP can be known from the slope of the approximate line and the difference amount DL2S (3L). Further, it is understood that 3TLP should be increased when the difference amount DL2S (3L) is greater than 0.18, and that 3TLP should be decreased when the difference amount DL2S (3L) is less than 0.18.

  Here, as shown in step S185 of FIG. 6, the difference amount DL2S (3L) does not need to be set to just 0.18, and if it is between 0.18 ± 0.04 as in the case of 2Ttop correction. Good. At this time, the maximum deterioration amount of the jitter value can be suppressed to only about 0.2%.

  From FIG. 16, the relationship between the final pulse width 4TLP of 4T and the difference amount DL2S (4L) can be approximately linearly approximated. The value of the difference amount DL2S (4L) when 4TLP is optimal, that is, when the jitter value is minimized is about 0.1. Therefore, it can be seen that when 4TLP is optimally corrected, it is sufficient to correct 4TLP so that the difference DL2S (4L) is about 0.1. At this time, the value of the target difference amount TH (4L) in step S186 in FIG. 6 is 0.1. Further, since the relationship between 4TLP and the difference amount DL2S (4L) can be approximately linearly approximated, the correction amount of 4TLP can be known from the slope of the approximate line and the difference amount DL2S (4L). Further, it is understood that 4TLP may be increased when the difference amount DL2S (4L) is greater than 0.1, and 4TLP may be decreased when the difference amount DL2S (4L) is less than 0.1.

  Here, as shown in step S185 of FIG. 6, the difference amount DL2S (4L) does not need to be set to just 0.1, and is in the range of 0.1 ± 0.04 as in the case of 2Ttop correction. Good. At this time, the maximum deterioration amount of the jitter value can be suppressed to only about 0.2%.

  From FIG. 17, the relationship between the kT intermediate pulse width kTMP and the difference DL2S (kM) can be approximately linearly approximated. The value of the difference amount DL2S (kM) when kTMP is optimum, that is, when the jitter value is minimized is about −0.02. Therefore, it can be seen that when kTMP is optimally corrected, kTMP may be corrected so that the difference DL2S (kM) is about −0.02. At this time, the value of the target difference amount TH (kM) in step S195 in FIG. 7 is −0.02. Further, since the relationship between kTMP and the difference amount DL2S (kM) can be approximately linearly approximated, the correction amount of kTMP can be known from the slope of the approximate line and the difference amount DL2S (kM). Furthermore, when the difference amount DL2S (kM) is larger than −0.02, kTMP is increased. When the difference amount DL2S (kM) is smaller than −0.02, kTMP is decreased. .

  Here, as shown in step S194 in FIG. 7, the difference amount DL2S (kM) does not need to be set to just −0.02, and between −0.02 ± 0.04 as in the case of 2Ttop correction. I just need it. At this time, the maximum deterioration amount of the jitter value can be suppressed to only about 0.5%.

  As described above, in the present embodiment, by detecting the width of the 2T space part according to the lengths of the front and rear marks, it is possible to optimally correct all the parameters relating to the write strategy, particularly the pulse width. You can know the amount of correction.

  In the embodiment of the present invention, the case of recording 1T modulation 2T to 9T marks has been described in the embodiment of the present invention. However, EFM + (8-16) modulation used in a DVD or the like. Even in other cases such as recording 3T to 11T and 14T marks, if the write strategy includes a parameter capable of correcting the pulse width, the same pulse width as that of the embodiment of the present invention can be obtained. Correction method can be applied.

It is an example of a structure of the optical recording / reproducing apparatus in embodiment of this invention. (A)-(e) is a figure which shows the example of the write strategy produced | generated at the time of recording on an optical disk in the optical recording / reproducing apparatus in embodiment of this invention. 5 is a flowchart showing an example of a procedure from optical disc insertion to recording in the optical recording / reproducing method according to the embodiment of the present invention. 4 is a flowchart showing an example of a procedure for correcting 2 Ttop of the pulse width in the optical recording and reproducing method according to the embodiment of the present invention. 6 is a flowchart showing an example of a procedure for correcting mTtop of the pulse width in the optical recording / reproducing method according to the embodiment of the present invention. 5 is a flowchart showing an example of a procedure for correcting a pTLP out of pulse widths in the optical recording / reproducing method according to the embodiment of the present invention. 5 is a flowchart showing an example of a procedure for correcting kTMP out of pulse widths in the optical recording and reproducing method according to the embodiment of the present invention. In the space width detection unit according to the embodiment of the present invention, the space width of the reproduction signal detected when both the front mark and the rear mark are 2T, and the case where the front mark is 3T to 9T and the rear mark is 2T are detected. It is a figure which shows the example of the space width | variety of the reproduction signal to be read. In the space width detection unit according to the embodiment of the present invention, the specific width of the reproduction signal detected when the front mark is 2T to 9T, the rear mark is mT, and the specific width of the front mark is 2T to 9T. It is a figure which shows the example of the space width of the reproduction signal detected when nT and a back mark are 2T. In the space width detection unit according to the embodiment of the present invention, the space width of the reproduction signal detected when the front mark is pT and the rear mark is a specific nT of 2T to 9T, the front mark is 2T, and the rear mark is 2T. It is a figure which shows the example of the space width of the reproduction signal detected in the case of specific nT of -9T. In the space width detection unit according to the embodiment of the present invention, the space width of the reproduction signal detected when the front mark is 4T and the rear mark is a specific nT of 2T to 9T, the front mark is sT, and the rear mark is 2T. It is a figure which shows the example of the space width of the reproduction signal detected in the case of specific nT of -9T. It is a figure which shows the relationship between 2Ttop and a jitter value, and 2Ttop and difference amount DL2S (2T) in the optical recording and reproducing method in embodiment of this invention. It is a figure which shows the relationship between 3Ttop and a jitter value, and 3Ttop and difference amount DL2S (3T) in the optical recording and reproducing method in embodiment of this invention. It is a figure which shows the relationship between 4Ttop and a jitter value, and 4Ttop and difference amount DL2S (4T) in the optical recording and reproducing method in embodiment of this invention. It is a figure which shows the relationship between 3TLP and a jitter value, and 3TLP and difference amount DL2S (3L) in the optical recording / reproducing method in embodiment of this invention. In the optical recording / reproducing method in this embodiment of this invention, it is a figure which shows the relationship between 4TLP and a jitter value, and 4TLP and difference amount DL2S (4L). It is a figure which shows the relationship between kTMP and a jitter value, and kTMP and difference amount DL2S (kM) in the optical recording and reproducing method in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Optical recording / reproducing apparatus, 110 Semiconductor laser, 120 Laser drive part, 130 Collimate lens, 140 Beam splitter, 150 Objective lens, 160 Optical disk, 170 Detection lens, 180 Light receiving element, 190 Head amplifier, 200 Prepit detection part, 210 Asymmetry detection Unit, 220 equalizer, 230 data encoder, 240 laser waveform control unit, 250 central control unit, 260 PRML signal processing unit, 270 data decoder, 280 jitter value detection unit, 290 space width detection unit.

Claims (32)

According to a write strategy parameter corresponding to a mark length of recorded data, an optical recording / reproducing method for recording data by irradiating an optical recording medium with laser light and reproducing recorded data,
Depending on the length of the mark of the data to be recorded, the mark is formed by irradiating the laser beam with a multi-pulse type write strategy including a single or a plurality of pulses and including a parameter for controlling the width of the pulse. A recording part forming step of forming and forming a recording part composed of a mark and a space located between the marks;
A space width reading step of reading the width of the signal portion corresponding to the space of the reproduction signal obtained by reading the recording unit;
Any two signal patterns of the reproduction signal composed of a combination of a signal portion corresponding to the space and a signal portion corresponding to marks before and after the signal portion corresponding to the space, the length of the space A pattern detection step of detecting two signal patterns having the same length, the length of one of the marks immediately before and after the space being equal, and the length of the other mark being different from each other;
A space width comparison step of comparing the widths of the signal portions corresponding to the spaces read in the space width reading step of the two signal patterns detected in the pattern detection step;
A pulse width correcting step of correcting the pulse width of the write strategy based on the result of the comparison of the width of the signal portion corresponding to the space;
A writing step of writing to the optical recording medium using the corrected pulse width.   The space width comparing step compares the width of the signal portion when the space length of the recording data is the shortest as the width of the signal portion corresponding to the space obtained by reading the recording portion. The optical recording / reproducing method according to claim 1. The pulse width correcting step includes
When correcting the width of the single pulse recorded with a write strategy consisting of a single pulse,
Based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the lengths of the marks immediately after the space are equal and the lengths of the marks immediately before the space are different from each other, Make corrections
3. The optical recording / reproducing method according to claim 1, wherein the mark immediately before the space in one of the two signal patterns is recorded by the single pulse. The pulse width correcting step includes
When correcting the width of the first pulse of the plurality of pulses of a write strategy including a plurality of specific pulses,
The pulse width is corrected based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the lengths of the marks immediately before the space are equal to each other and the mark lengths immediately after the space are different from each other. Done
4. The light according to claim 1, wherein a mark immediately after the space in one of the two signal patterns is recorded by a write strategy including the specific plurality of pulses. 5. Recording and playback method. The pulse width correcting step includes
Of a plurality of pulses of a write strategy including a plurality of specific pulses,
When correcting the width of the last pulse or the width of the intermediate pulse located between the first pulse and the last pulse,
Based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the lengths of the marks immediately after the space are equal and the lengths of the marks immediately before the space are different from each other, Make corrections,
5. The light according to claim 1, wherein a mark immediately before the space in one of the two signal patterns is recorded by a write strategy including the specific plurality of pulses. Recording and playback method. The pulse width correcting step includes
When correcting the width of the single pulse recorded with a write strategy consisting of a single pulse,
When the mark immediately before the space is recorded with a write strategy composed of the single pulse,
Based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the mark immediately before the space is recorded with a write strategy composed of the plurality of pulses, 6. The optical recording / reproducing method according to claim 1, wherein correction is performed. The pulse width correcting step includes
As a case where the mark immediately before the space is recorded with a write strategy composed of the plurality of pulses,
The optical recording / reproducing method according to claim 6, wherein the number of pulses constituting the write strategy is any value. The pulse width correcting step includes
When correcting the width of the first pulse of the plurality of pulses of a write strategy including a plurality of specific pulses,
When the mark immediately after the space is recorded with a write strategy composed of the single pulse,
Based on the comparison result of the width of the signal portion corresponding to the space of the two signal patterns when the mark immediately after the space is recorded by a write strategy including the specific plurality of pulses, The optical recording / reproducing method according to claim 1, wherein correction is performed. The pulse width correcting step includes
When correcting the width of the last pulse of the plurality of pulses of the write strategy including a plurality of specific pulses,
When the mark immediately before the space is recorded with a write strategy composed of the single pulse,
Based on the comparison result of the width of the signal portion corresponding to the space of the two signal patterns when the mark immediately before the space is recorded with the write strategy composed of the specific plurality of pulses 9. The optical recording / reproducing method according to claim 1, wherein the width is corrected. The pulse width correcting step includes
When correcting the width of the intermediate pulse located between the first pulse and the last pulse among the plurality of pulses of the write strategy including a specific plurality of pulses,
The mark immediately before the space is recorded with a write strategy having only one intermediate pulse;
Based on the comparison result of the width of the signal portion corresponding to the space of two signal patterns when the mark immediately before the space is recorded with a write strategy having two or more intermediate pulses, 10. The optical recording / reproducing method according to claim 1, wherein correction is performed. The pulse width correcting step includes
As a case where the mark immediately before the space is recorded with a write strategy having two or more intermediate pulses,
The optical recording / reproducing method according to claim 10, wherein the number of intermediate pulses is a specific value of two or more or an arbitrary combination. The pulse width correcting step includes
After correcting the pulse width of the write strategy composed of the single pulse,
The optical recording according to any one of claims 1 to 11, wherein a pulse width of a first pulse and a last pulse among a plurality of pulses of a write strategy composed of the plurality of pulses is corrected. Playback method.   13. The pulse width correcting step performs the correction so that a difference in width of a signal portion corresponding to a space between the two signal patterns matches a preset target value. The optical recording / reproducing method according to any one of the above. The pulse width correcting step includes
13. The optical recording according to claim 1, wherein the correction is performed so that a difference in width of a signal portion corresponding to a space between the two signal patterns falls within a preset allowable range. Playback method.   In the pulse width correction step, the direction of correction of the pulse width is determined based on the magnitude relationship between the difference between the widths of the signal portions corresponding to the spaces of the two signal patterns and the preset target value. The optical recording / reproducing method according to claim 1.   In the pulse width correcting step, a relationship between a difference in width of the signal portion corresponding to the space of the two signal patterns and a change amount of the pulse width is obtained in advance, and the pulse width is corrected based on the relationship. The optical recording / reproducing method according to claim 1, wherein: An optical recording / reproducing apparatus for recording data by irradiating an optical recording medium with laser light according to a write strategy parameter corresponding to a mark length of the recording data, and reproducing the recorded data,
Depending on the length of the mark of the data to be recorded, the mark is formed by irradiating the laser beam with a multi-pulse type write strategy including a single or a plurality of pulses and including a parameter for controlling the width of the pulse. Recording portion forming means for forming and forming a recording portion composed of a mark and a space located between the marks;
Space width reading means for reading the width of the signal portion corresponding to the space of the reproduction signal obtained by reading the recording unit;
Any two signal patterns of the reproduction signal composed of a combination of a signal portion corresponding to the space and a signal portion corresponding to marks before and after the signal portion corresponding to the space, the length of the space Pattern detecting means for detecting two signal patterns having the same length, the length of one of the marks immediately before and after the space being equal, and the length of the other mark being different from each other;
Space width comparison means for comparing the widths of the signal portions corresponding to the spaces, read by the space width reading means, of the two signal patterns detected by the pattern detection means;
Pulse width correcting means for correcting the pulse width of the write strategy based on the result of the comparison of the width of the signal portion corresponding to the space;
An optical recording / reproducing apparatus comprising: writing means for writing to the optical recording medium using the corrected pulse width.   The space width comparing means compares the width of the signal portion when the space length of the recording data is the shortest as the width of the signal portion corresponding to the space obtained by reading out the recording portion. The optical recording / reproducing apparatus according to claim 17. The pulse width correcting means includes
When correcting the width of the single pulse recorded with a write strategy consisting of a single pulse,
Based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the lengths of the marks immediately after the space are equal and the lengths of the marks immediately before the space are different from each other, Make corrections,
The optical recording / reproducing apparatus according to claim 17 or 18, wherein the mark immediately before the space of one of the two signal patterns is recorded by the single pulse. The pulse width correcting means includes
When correcting the width of the first pulse of the plurality of pulses of a write strategy including a plurality of specific pulses,
The pulse width is corrected based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the lengths of the marks immediately before the space are equal to each other and the mark lengths immediately after the space are different from each other. Done
20. The light according to claim 17, wherein the mark immediately after the space in one of the two signal patterns is recorded with a write strategy including the specific plurality of pulses. Recording / playback device. The pulse width correcting means includes
Of a plurality of pulses of a write strategy including a plurality of specific pulses,
When correcting the width of the last pulse or the width of the intermediate pulse located between the first pulse and the last pulse,
Based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the lengths of the marks immediately after the space are equal and the lengths of the marks immediately before the space are different from each other, Make corrections
21. The light according to claim 17, wherein the mark immediately before the space in one of the two signal patterns is recorded by a write strategy including the specific plurality of pulses. Recording / playback device. The pulse width correcting means includes
When correcting the width of the single pulse recorded with a write strategy consisting of a single pulse,
When the mark immediately before the space is recorded with a write strategy composed of the single pulse,
Based on the comparison result of the widths of the signal portions corresponding to the spaces of the two signal patterns when the mark immediately before the space is recorded with a write strategy composed of the plurality of pulses, The optical recording / reproducing apparatus according to claim 17, wherein correction is performed. The pulse width correcting means includes
As a case where the mark immediately before the space is recorded with a write strategy composed of the plurality of pulses,
The optical recording / reproducing apparatus according to claim 22, wherein the number of pulses constituting the write strategy is any value. The pulse width correcting means includes
When correcting the width of the first pulse of the plurality of pulses of a write strategy including a plurality of specific pulses,
When the mark immediately after the space is recorded with a write strategy composed of the single pulse,
Based on the comparison result of the width of the signal portion corresponding to the space of the two signal patterns when the mark immediately after the space is recorded by a write strategy including the specific plurality of pulses, The optical recording / reproducing apparatus according to claim 17, wherein correction is performed. The pulse width correcting means includes
When correcting the width of the last pulse of the plurality of pulses of the write strategy including a plurality of specific pulses,
When the mark immediately before the space is recorded with a write strategy composed of the single pulse,
Based on the comparison result of the width of the signal portion corresponding to the space of the two signal patterns when the mark immediately before the space is recorded with the write strategy composed of the specific plurality of pulses The optical recording / reproducing apparatus according to claim 17, wherein the width is corrected. The pulse width correcting means includes
When correcting the width of the intermediate pulse located between the first pulse and the last pulse among the plurality of pulses of the write strategy including a specific plurality of pulses,
The mark immediately before the space is recorded with a write strategy having only one intermediate pulse;
Based on the comparison result of the width of the signal portion corresponding to the space of two signal patterns when the mark immediately before the space is recorded with a write strategy having two or more intermediate pulses, 26. The optical recording / reproducing apparatus according to claim 17, wherein correction is performed. The pulse width correcting means includes
As a case where the mark immediately before the space is recorded with a write strategy having two or more intermediate pulses,
27. The optical recording / reproducing apparatus according to claim 26, wherein the number of intermediate pulses is a specific value of two or more or an arbitrary combination. The pulse width correcting means includes
After correcting the pulse width of the write strategy composed of the single pulse,
The optical recording according to any one of claims 17 to 27, wherein a pulse width of a first pulse and a last pulse among a plurality of pulses of a write strategy composed of the plurality of pulses is corrected. Playback device.   29. The pulse width correcting means performs the correction so that a difference in width of a signal portion corresponding to a space between the two signal patterns matches a preset target value. The optical recording / reproducing apparatus according to any one of the above. The pulse width correcting means includes
29. The optical recording according to claim 17, wherein the correction is performed so that a difference in width of a signal portion corresponding to a space between the two signal patterns falls within a preset allowable range. Playback device.   The pulse width correcting means determines the direction of correction of the pulse width based on the magnitude relationship between the difference between the widths of the signal portions corresponding to the spaces of the two signal patterns and the preset target value. The optical recording / reproducing apparatus according to claim 17.   The pulse width correcting means obtains in advance a relationship between a difference in width of the signal portion corresponding to the space of the two signal patterns and a change amount of the pulse width, and corrects the pulse width based on the relationship. 32. The optical recording / reproducing apparatus according to any one of claims 17 to 31.

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