JP4911224B2 - Signal recording condition adjusting method for optical information recording medium, information recording / reproducing apparatus - Google Patents

Description

  The present invention relates to a signal recording condition adjusting method and an information recording / reproducing apparatus for adjusting conditions for recording a signal on an optical information recording medium.

  An optical disk apparatus (information recording / reproducing apparatus) is an apparatus that records information on an optical information recording medium (optical disk) or reproduces recorded information using an optical head. In such an optical disc apparatus, there are several factors that influence the performance of the optical disc apparatus during recording or reproduction. Regarding recording, the control of the amount of irradiation light for forming the recording mark is a very important factor among them. In general, control of the amount of irradiation light includes control of the output level (amplitude direction) such as recording power and bias power, and control of the pulse width and pulse position (time direction) of the laser pulse. This is collectively called a recording strategy.

  1A to 1F show examples of recording strategies. FIG. 1A shows a waveform example of an input signal indicating a mark portion and a space portion. Waveforms for forming the mark portion are divided into a case where the recording power is divided in time and applied in a pulse shape, or a case where the recording power is applied based on a rectangular shape. FIG. 1B shows an example of a pulse train type recording waveform having ternary levels of recording power, erasing power, and bias power. A recording power is applied in a pulse form at the mark portion, and a constant erasing power is applied at the space portion. FIG. 1C shows an example of a pulse train type recording waveform having binary levels of recording power and bias power. Recording power is applied in a pulsed manner to the mark portion. FIG. 1D shows an example of a rectangular waveform having binary levels of recording power and bias power, and the recording power is applied in a rectangular shape at the mark portion. FIG. 1E shows a waveform example having a total of four power levels of recording powers 1, 2, 3 and bias power, and the recording power is applied to the mark portion in a rectangular shape with both ears. FIG. 1F shows a waveform example including a cooling pulse in a waveform based on a rectangle having four levels of recording power 1, recording power 2, erasing power, and bias power.

  As described above, there are various types of recording strategies, and the output level (power level) and the pulse shape differ depending on the type of medium and the optical disk device to be recorded. For example, a DVD-R (Digital Versatile Disc-Recordable) that is a recordable optical disc that can be recorded only once uses a rectangular recording strategy, and a DVD-RW (DVD-ReWriteable) that is a re-writable optical disc. A multi-pulse type recording strategy is often used. In addition, the laser pulse output level for the space where no recording mark is formed has an effect of erasing the bias power in a write once (write-once) medium, and the erasing power because it has a function of erasing a recording mark that has existed in a rewritable optical disk. being called.

  In the case of HD DVD (High Definition DVD), which is the next generation DVD that has begun to be shipped in recent years, write-once HD DVD-R (HD DVD-Recordable) is also rewritable type HD DVD-RW (HD DVD-Rewriteable) or HD A multi-pulse type recording strategy is mainly used for DVD-RAM (HD DVD-Random Access Memory).

  The recording strategy greatly affects the recording / reproducing performance of the optical disc. Therefore, many recording methods, recording strategies, and adjustment methods for recording strategies have been devised, and there are many report examples.

  As a method for adjusting a recording strategy, the technique disclosed in Japanese Patent Laid-Open No. 2000-182244 assigns several levels to recording power and recording strategy parameters, conducts exhaustive experiments for each combination, and selects the optimum one. The adjustment method to be selected. In the method disclosed in Japanese Patent Laid-Open No. 2000-030254, the adjustment of the recording strategy pulse width and the adjustment of the recording power are performed separately, and the recording power is determined using the theoretical mark length as a guideline. It is. Japanese Unexamined Patent Application Publication No. 2005-216347 discloses a DVD-R recording strategy adjustment method performed while checking margins.

  Furthermore, Japanese Patent Laid-Open No. 2006-066068 discloses a method for obtaining a recording strategy by calculation. This is obtained by an experiment in which constants used for calculation are preliminarily determined based on a recommended value recorded for each optical disk and a characteristic of an optical pickup optical system provided in the recording apparatus. The recording device includes the obtained constant, and the pulse width used for recording is calculated by calculation.

  Japanese Patent Laid-Open No. 2006-164485 discloses a method for setting a recording strategy in a rewritable DVD disc. First, 3T, 4T, and 5 to 14T pulse widths are individually changed by a predetermined amount and recorded. The inherent expansion / contraction amount is calculated from the reproduced mark length and the theoretical length of each mark. The rate of change of the inherent expansion / contraction amount of each mark when the pulse widths of 3T, 4T, and 5 to 14T are individually changed by a predetermined amount with respect to the reference write strategy is calculated. The variance of the rate of change of the inherent expansion / contraction amount of each mark is calculated, and a write strategy is set so that this variance is minimized.

  Next, technologies related to next-generation optical disks will be described. In the next generation optical disc (HD DVD and BD (Blu-ray Disc)) with higher density, laser light (short wavelength laser) with a light source wavelength of about 400 to 410 nm is used to write to and read from the disc. Is done. The HD DVD, which is the next-generation DVD, has a recording density that is three times higher than that of the conventional DVD, and PRML (Partial Response Maximum Likelihood) technology is used for signal readout. In the PRML technique, interference between patterns is estimated in advance, and a signal pattern that seems to be likely from a reproduced signal is estimated and determined. There are numerous papers on the PRML technology. For example, “High-density recording / reproduction signal processing technology for next-generation DVD ITE Technical Report Vol. 27, No. 43, PP. 13-16 MMS 2003-48, CE 2003-43 (Jul. 2003). See Nakano et al.

  In HD DVD, PRML of PR (1, 2, 2, 2, 1) with a very large interference is used. For the time being, it means that the state of the trailing and leading edges of other recording marks before and after the recording mark greatly affects the quality of the reproduced signal. This also means that the adjustment of the recording strategy becomes a very delicate adjustment.

  When performing PRML detection, there are several indicators used for quality evaluation of the reproduced waveform. One of them is PRSNR (Partial Response Signal to Noise Ratio). This is an index that replaces the jitter conventionally used for evaluating the signal quality of the reproduced waveform. It has been found that jitter cannot be used as an evaluation index in an optical disc with a high density such as HD DVD. PRSNR is an index adopted in HD DVD. PRSNR is a signal quality evaluation index instead of jitter, and is an SNR value in PRML detection. Further, the PRSNR can be converted into an error rate. However, contrary to jitter and error rate, the higher this value, the better the signal quality. The details of PRSNR including conversion to error rate are described in “Japan-Journal of Applied Physics Vol. al ".

  An adjustment method based on PRML detection is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-319231. This method uses the frequency distribution of the signal amplitude level after partial response processing, derives a dispersion value by a theoretical formula assuming a normal distribution, and when close to a predetermined dispersion value, reproduction power, focus offset, recording power, Adjust lens position, recording data and clock phase, etc.

  As another method for evaluating the quality of the reproduced waveform, there is a method of directly obtaining the error rate and the number of error bytes. HD DVD also has a different modulation code than conventional DVD. The modulation code of HD DVD is a modulation code called ETM (Eight to Twelve Modulation). The shortest mark length or shortest space length is 2T (T is a channel clock period). On the other hand, a conventional DVD uses a modulation code called 8/16 modulation, and its shortest mark length or shortest space length is 3T. Therefore, the recording strategy is different between the two. For example, in the case of DVD-R, a mark portion having a length kT (k is a natural number of 3 or more) may be recorded with k-2 pulses. In the case of HD DVD-R, since the shortest mark length is 2T, there is no output pulse when recording the shortest mark with k-2 pulses. That is, recording must be performed with at least k−1 pulses. This is not just a discussion of the number of pulses, but it means that the concept of the recording strategy itself must be changed between DVD and HD DVD. In other words, knowledge on DVD cannot be used effectively.

  Japanese Patent Application Laid-Open No. 2003-162817 discloses an optical storage in which multi-valued data recorded according to information to be recorded is recorded as a mark by irradiating an optically rewritable optical storage medium with a laser. A medium recording method is disclosed. This recording method includes a first step and a second step. In the first step, the front and rear mark lengths are detected when marks are recorded on the optical storage medium. In the second step, the timing for irradiating the optical storage medium with laser is set in accordance with the mark lengths detected before and after detected in the first step, and laser irradiation is performed at the set timing, and the multi-value data A mark is recorded.

  Japanese Patent Laid-Open No. 2006-318594 discloses a recording method for recording a recording mark corresponding to multi-value data on a recording medium in units of recording cells. In this recording method, a recording mark group is formed on a recording medium by irradiating the recording medium with laser light having a recording pulse waveform generated based on a recording signal synchronized with a cell clock period. A reproduction signal waveform is obtained by reading the recording mark group. The reproduced signal waveform is sampled at a period shorter than the cell clock period, and an error in the signal level and an error in the peak position between the sample point of the reproduced signal waveform and the ideal signal waveform are evaluated. As a result of the evaluation, the laser beam pulse width of the recording pulse waveform or the laser beam irradiation timing correction amount is determined.

  As described above, when the density becomes as high as that of an HD DVD, the adjustment of the recording strategy becomes very delicate. In addition, adjustment suitable for PRML detection that is not used in the conventional DVD must be made. This is also due to the fact that PRML detection is a detection method that positively utilizes intersymbol interference of recorded marks. In such a case, the parameters of the recording strategy often influence each other. Therefore, an adjustment method that is rough and assumes that each parameter independently affects the signal quality, such as the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2000-182244, obtains an optimal recording strategy. It has become difficult. Further, even if the parameter is adjusted by introducing an index using a deviation from the theoretical value of the longest recording mark (difference between the 14T space width and the 14T mark width), as shown in the above-mentioned Japanese Patent Laid-Open No. 2000-030254. In such a method, it is difficult to obtain an optimum recording strategy when the intersymbol interference increases rapidly due to the high density and the recording mark itself is affected by the recording marks before and after it.

  In Japanese Patent Laid-Open No. 2006-066068, a conversion constant and a target asymmetry value to be converted into a pulse width to be actually used are obtained by conducting an experiment in advance based on a recommended recording strategy value recorded on an optical disc, These values need to be held by the device. Therefore, when applied to an unknown optical disc, accurate adjustment cannot be performed. In Japanese Patent Laid-Open No. 2006-164485, even if only the dispersion of the recording state is suppressed, the PRML detection does not necessarily achieve good recording unless it matches the assumed detection level when a predetermined response characteristic is assumed. Furthermore, in PRML detection, each mark or each space does not necessarily have to be the theoretical length, and it is only necessary to record / reproduce so that a reproduction waveform composed of continuous mark spaces has an assumed response. So it's not always a good solution.

  The conventional method is not a PRML detection but a binary detection method for detection using a slicer. Therefore, the system using the PRML detection method cannot be used as it is. Similarly, the methods disclosed in Japanese Patent Laid-Open Nos. 2005-216347, 2006-0660668, and 2006-164485 are also adjustment methods that do not assume PRML detection, and use conventional jitter. Is. In a high-density optical disk such as HD DVD, a signal quality evaluation index called jitter cannot be measured already.

  In Japanese Patent Laid-Open No. 2002-319231, a variance value of a signal amplitude level after partial response processing is derived by a theoretical formula assuming a normal distribution. In a system that has been densified to such an extent that introduction of PRML is necessary, the intersymbol interference of the read reproduction signal is large. Therefore, each distribution corresponding to the assumed level of the actual read signal may be a distribution whose symmetry is broken with respect to the distribution center, for example. Therefore, this method using a theoretical formula assuming a normal distribution cannot always be adjusted accurately. Further, only the variance value (signal spread distribution) is considered, and the deviation from the signal level expected to be taken by the read signal (average position of the distribution) is not considered, so that it is not always sufficient. It is not an evaluation scale. On the other hand, an example of introducing a difference metric is also shown. However, in the adjustment of the recording strategy, since a plurality of parameters influence each other, it is difficult to perform complicated adjustment using only this index.

  In many adjustment methods, a modulation code in which only a signal of 3T or more exists is assumed, so that the recording strategy is different from that of HD DVD or the like. That is, the conventional technology cannot be applied as it is to an HD DVD or the like.

  Thus, in developing a high-density optical disk, it is necessary to clarify how to obtain the best recording strategy quickly and accurately in a system using high-density PRML such as HD DVD. It is a very big problem.

  An object of the present invention is to provide a method for adjusting a signal recording condition for an optical information recording medium and an information recording / reproducing apparatus for quickly and accurately obtaining the best recording strategy. Another object of the present invention is to provide a method for adjusting a signal recording condition on an optical information recording medium and an information recording / reproducing apparatus that do not wastefully use an adjustment area.

  In an aspect of the present invention, a method for adjusting a signal recording condition on an optical information recording medium includes a step of trial recording, a step of measuring, a step of selecting parameter candidate values, and a step of generating a combination of a plurality of parameter values And an iterative step and an optimum value selection step. In the recording step, based on a recording strategy including a plurality of adjustable parameters, an optical information recording medium is irradiated with intensity-modulated laser light while changing a value of a first parameter among the plurality of parameters. A pattern sequence having a mark portion and a space portion is recorded on a trial basis. In the quality measurement step, the test-recorded pattern sequence is reproduced, and a signal quality value indicating the reproduction signal quality is measured corresponding to each value of the first parameter. In the candidate selection step, one or more parameter candidate values are selected from each value of the first parameter based on the signal quality value. In the step of generating a combination of a plurality of parameter values, the value of the first parameter is replaced and fixed with the selected plurality of parameter candidate values, and the second parameter of the plurality of parameters is selected as a parameter whose value is to be changed Is done. In the repetition step, the recording step, the quality measurement step, the candidate selection step, and the step of generating a plurality of parameter value combinations are repeated. In the optimum value selection step, a combination of parameter candidate values that minimizes the variance value of the error between the reproduction signal waveform reproduced from the pattern string and the reference reproduction waveform calculated based on the pattern string after the repetition in the repetition step. Selected.

  In another aspect of the present invention, an information recording / reproducing apparatus includes an optical head unit, a reproducing unit, a signal quality calculating unit, and a recording strategy adjuster. The optical head unit irradiates the optical information recording medium with intensity-modulated laser light while changing the value of the first parameter among the plurality of parameters based on a recording strategy including a plurality of adjustable parameters. Thus, a pattern sequence having a mark portion and a space portion is recorded on a trial basis, the pattern sequence recorded on the optical information recording medium is read, and an electric signal is output. The reproduction unit generates a reproduction waveform signal based on the electrical signal. The signal quality calculation unit measures a signal quality value indicating the reproduction signal quality of the reproduction waveform signal corresponding to each value of the first parameter based on the reproduction waveform signal. The recording strategy adjuster selects one or a plurality of parameter candidate values from each value of the first parameter based on the signal quality value, and replaces the value of the first parameter with the plurality of selected parameter candidate values. The second parameter of the plurality of parameters is selected as a parameter whose value is to be changed. Further, the recording strategy adjuster has a variance value of an error between the reproduction signal waveform reproduced from the pattern string and the reference reproduction waveform calculated based on the pattern string after repeating the test recording and the measurement of the signal quality value. The parameter candidate value combination that minimizes is selected as the adjustment result of the signal recording conditions.

The objects, effects, and features of the present invention will become more apparent from the description of the embodiments in conjunction with the accompanying drawings.
1A to 1F are diagrams showing types of recording strategies. FIG. 2 is a diagram showing a schematic configuration of the information recording / reproducing apparatus according to the embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of the RF circuit unit. 4A to 4B are diagrams showing setting of a recording strategy of the (k-1) type pulse train. FIG. 5 is a flowchart showing the operation of the information recording / reproducing apparatus. FIG. 6 is a diagram illustrating the adjustment order of the variable parameters. FIG. 7 is a diagram illustrating a configuration of acquired information. FIG. 8 is a diagram illustrating the measurement result of PRSNR when the cooling pulse width is changed. FIG. 9 is a diagram illustrating an example of error variance values when the combinations of recording strategy parameters are different. FIG. 10 is a diagram illustrating a result of measuring a power margin using PRSNR as an evaluation index when combinations of recording strategy parameters are different. FIG. 11 is a flowchart showing another operation of the information recording / reproducing apparatus. FIG. 12 is a diagram illustrating the relationship between the adjustment step and the required signal quality (PRSNR). FIG. 13 is a diagram illustrating the relationship between the adjustment step and the required signal quality (error rate).

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 2 shows a schematic diagram of the configuration of the information recording / reproducing apparatus according to the embodiment of the present invention. The information recording / reproducing apparatus 1 includes a spindle drive system 9, an optical head unit 20, an RF circuit unit 3, a demodulator 4, a system controller 5, a modulator 6, an LD drive unit 7, and a servo controller 8.

  The spindle drive system 9 drives the optical disc 10. The optical head unit 20 includes a laser diode (LD) 26, an objective lens 28, a beam splitter 25, and a light receiving unit 22, and irradiates the optical disk 10 with laser light from the laser diode (LD) 26 via the objective lens 28. Reflected light from 10 is detected by the light receiving unit 22. That is, the laser diode (LD) 26 emits laser light whose intensity is modulated based on a pattern sequence having a mark portion and a space portion indicating data to be recorded. The laser light emitted from the laser diode 26 is condensed by the objective lens 15 and irradiated onto the optical disk 10. The reflected light is separated from the emitted light by the beam splitter 25, detected by the light receiving unit 22, converted into an electric signal, and output to the RF circuit unit 3.

  The RF circuit unit 3 performs processing such as filtering on the input signal to measure the signal quality, and outputs a value indicating the signal quality to the system controller 5. Details of the RF circuit unit 3 will be described later. The demodulator 4 demodulates the output signal of the RF circuit unit 3 and outputs it to the system controller 5. The modulator 6 modulates a signal to be recorded. The output of the modulator 6 is output to the LD drive unit 7 and also to the RF circuit unit 3 for signal quality measurement. The LD driving unit 7 drives the laser diode 26 of the optical head unit 20 based on the output signal of the modulator 7. The servo controller 8 controls the servo signal. The system controller 5 includes a recording strategy adjuster 15 and adjusts the recording strategy including the recording power and the bias power. Further, the system controller 5 controls the entire apparatus.

  As shown in FIG. 3, the RF circuit unit 3 includes a prefilter 31, an auto gain control circuit (AGC) 32, an A / D converter (ADC), a phase locked loop circuit (PLL) 35, an adaptive equalizer 37, A discriminator 38 is provided to convert the input signal into a binarized signal. Further, the RF circuit unit 3 includes a storage unit 30 that holds recording data output from the modulator 6 and a signal quality calculation unit 40 that calculates signal quality. The storage unit 30 holds the recording data output from the modulation unit 6, that is, the pattern sequence used for recording, and supplies the recording data held based on the control of the system controller 5 to the signal quality calculation unit 40. The signal quality calculation unit 40 calculates the signal quality based on the outputs of the adaptive equalizer 37 and the discriminator 38 and the output of the storage unit 30.

  The input signal input from the optical head unit 20 is filtered by the pre-filter 31, subjected to amplitude control by the auto gain control circuit 32, and then digitized by the A / D converter 34. From the digital signal, a clock signal is extracted by the phase-locked loop circuit 35, and the signal is synchronized with the channel frequency and output to the adaptive equalizer 37.

  The adaptive equalizer 37 is typically realized by an FIR filter, and converts an input signal into an equalized reproduction signal so as to approach a PR (1, 2, 2, 2, 1) characteristic. The tap coefficient of the FIR filter is changed using an LMS (least mean square) algorithm, and the frequency characteristic is corrected. The equalized reproduction signal whose frequency characteristics have been corrected by the adaptive equalizer 37 is output to a discriminator 38 including a Viterbi decoder and also output to a signal quality calculation unit 40.

  The discriminator 38 receives the equalized reproduction signal output from the adaptive equalizer 37, selects the path with the shortest Euclidean distance from the equalized reproduction signal, and selects 2 code bit sequences corresponding to the selected path. Output as a digitized signal (estimated pattern string). The binarized signal is output to the demodulator 4, fed back to the adaptive equalizer 37, and output to the signal quality calculation unit 40.

  The signal quality calculation unit 40 includes a reference waveform signal generator 41, an error calculator 42, a timing adjustment circuit 43, an error rate calculator 45, a PRSNR calculator 47, and a variance calculator 48. The reference waveform signal generator 41 generates a reference (ideal) reproduction waveform signal when a predetermined response characteristic is assumed for the recording / reproduction channel, based on the binarized signal output from the discriminator 38. The reference waveform signal generator 41 may generate a reference reproduction waveform based on the recording data stored in the storage unit 30. The error calculator 42 calculates a difference (error) between the reproduction waveform based on the equalized reproduction signal whose timing is adjusted via the timing adjustment circuit 43 and the reference reproduction waveform output from the reference waveform signal generator 41.

ここで、Ｎは１以上の整数とする。The PRSNR calculator 47 calculates a PRSNR value based on the error between the reproduction waveform output from the error calculator 42 and the reference reproduction waveform. Further, the variance calculator 48 calculates an error variance value (error variance) based on the error between the reproduction waveform output from the error calculator 42 and the reference reproduction waveform. The difference between the waveform data indicating the reproduction signal waveform sampled and digitized by the A / D converter 34 and the waveform data indicating the reference reproduction waveform calculated by the error calculator 42 is Xk, and is sampled during a period for obtaining the dispersion value. When the number of samples (number of samples) is N, the variance value σ ² is calculated by the following equation using the average sum of squares of the error Xk and the average sum of squares of the error Xk.

Here, N is an integer of 1 or more.

  The error rate calculator 45 calculates an error rate based on the recording data stored in the storage unit 30 and the binarized signal output from the discriminator 38. The error rate is calculated as necessary. The PRSNR value, variance value, and error rate calculated by the signal quality calculation unit 40 are output to the system controller 5.

  The recording strategy adjuster 15 incorporated in the system controller 5 includes a PRSNR value, dispersion value, error rate and equalization error information supplied from the RF circuit unit 3, and the number of error bytes in a predetermined ECC (Error Correction Code) block. By recognizing the relationship between recording conditions and signal quality. The number of error bytes in the ECC block is obtained from the data string demodulated by the demodulator 4. Based on the measurement results of these signal qualities, the recording strategy adjuster 15 controls a series of adjustment sequences to extract the optimum recording strategy parameters and parameters, that is, extract and select the pulse widths of the strategy constituting pulses. I do.

  Next, the operation of the recording strategy adjuster 15 of the information recording / reproducing apparatus 1 will be described. In the following description, the operation of the information recording / reproducing apparatus is exemplified on the assumption of a write-once optical disc (for example, HD DVD-R) that can be recorded only once corresponding to the HD DVD standard. The physical format of the optical disk is an in-groove format with a bit pitch of 0.15 μm and a track pitch of 0.40 μm.

  In an optical disc such as an HD DVD-R, a type of medium in which the reflectivity of the mark increases when recording is called a low-to-high medium. Conversely, a type of medium in which the reflectivity of the mark decreases is This is called a high-to-low medium. In the present embodiment, description will be made assuming that a Low-to-High medium is used. The optical disc includes a disc-shaped transparent substrate made of polycarbonate. The substrate has a thickness of 0.6 mm and a diameter of 12 cm. A recording film (recording layer) is formed on the substrate, and guide grooves called pregrooves are formed. At the time of recording and reproducing information, a light beam of an information recording / reproducing apparatus (optical disc drive) can be scanned along the guide groove. The information recording / reproducing apparatus 1 records a pattern sequence including information marks and spaces on the recording layer.

  Further, it is assumed that the LD wavelength of the light emitted from the laser diode 26 of the optical head unit 20 is 405 nm, and the NA (numerical aperture) of the objective lens is 0.65. Furthermore, the recording strategy waveform is defined as shown in FIGS. 4A and 4B. FIG. 4A shows an NRZI (non-return to zero inverted) waveform. FIG. 4B shows a waveform when a 5T mark of the (k-1) type pulse train corresponding to the NRZI waveform is recorded. There are a first pulse and a last pulse having a predetermined recording power level, and two intermediate pulses therebetween. These pulses are called heating pulses because they heat the recording layer. There is a bottom power level between each pulse. Further, a bottom power level cooling pulse is provided after the final pulse. The bottom power level is preferably as close to zero level as possible, and is set to 0.1 mW here.

  FIG. 5 shows a flowchart of the recording strategy adjustment operation of the information recording / reproducing apparatus 1. The operation of the recording strategy adjuster 15 will be described below with reference to FIG.

  When the optical disk 10 is loaded in the information recording / reproducing apparatus 1, the system controller 5 moves the optical head unit 20 to the system information area of the optical disk 20, reads the disc manufacturing information from the system information area, and reads the disk based on the information. Type, disk manufacturer name, etc. Based on the acquired information, the system controller 5 determines that the loaded optical disk 10 is the medium A, and acquires a parameter table related to the medium A. For example, as shown in FIG. 7, the parameter table includes a recording power, a bias power, an assumed PRSNR value, a shortest mark pulse width, a 3T head pulse width, a head pulse width of 4T or more marks, an intermediate pulse width, Information on typical pulse width such as final pulse width and cooling pulse width is provided. These values are recommended values adjusted in advance by a predetermined device. This parameter table may be stored in the system information area of the optical disc 10 or may be held by the information recording / reproducing apparatus 1. When the information recording / reproducing apparatus 1 holds the information recording / reproducing apparatus 1, the information recording / reproducing apparatus 1 searches based on the disc manufacturer name and the type of disc acquired from the optical disc 10 to obtain a parameter table. The case where there is no parameter table prepared in advance will be described later.

  The recording strategy adjuster 15 sets the recording power to 9.0 mW and the bias power to 3.6 mW as predetermined recording power based on the parameter table. The first pulse, intermediate pulse, and final pulse all have the same pulse width, and the pulse width of the cooling pulse is zero. A predetermined test pattern is recorded on the optical disc by changing the basic pulse width to approximately 0.03 T increments in the range from 0.38T to 0.86T. At this time, the edge of the pulse whose position is changed by changing the pulse width is the leading edge of any pulse. The recorded test pattern is reproduced, and the recording strategy adjuster 15 obtains the best basic pulse width based on the signal quality (PRSNR), and sets it as the basic pulse width of the base strategy. Thus, a base strategy is set based on the acquired information (step S100).

  Each parameter of the recording strategy is adjusted based on the base strategy. The recording strategy parameters that can be adjusted in the information recording / reproducing apparatus 1 include the pulse width of the shortest mark, the recording power including the recording power value and the bias power value, the head pulse width of the mark longer than the shortest mark, the final pulse width, and the cooling pulse width Each of them is selected as a variable parameter in the order shown in FIG. That is, one of these parameters is made variable, its variable range and step size are set, and the values of the other parameters are fixed (step S110).

  When the variable range and step size of the variable parameter are set, the signal quality for each variable value is measured. That is, a predetermined test pattern is recorded on the optical disc at each variable value, and the recorded test pattern is reproduced to calculate and measure the signal quality (step S120).

  When the signal quality for each variable value is measured, the recording strategy adjuster 15 selects a parameter value candidate based on the measurement result. For example, in the adjustment of the variable parameter, some values whose signal quality is better than a predetermined value are set as parameter value candidates. Alternatively, in the adjustment of the variable parameter, a predetermined number of parameter values are set as parameter value candidates in order of good signal quality. The parameter value selected as the parameter value candidate in this step is used as a new value of the parameter of the base strategy when obtaining the next variable parameter (step S130).

  Steps S110 to S130 are repeated while changing the variable parameters in the order shown in FIG. Accordingly, the parameter candidate values of the variable parameters are combined, and the parameter value candidates are obtained while gradually improving the signal quality (step S140).

  When the parameter candidate values for all the variable parameters are obtained, the recording strategy adjuster 15 obtains the optimum combination of parameter values among them. That is, since the parameter candidate value of each variable parameter is selected and the value is used when selecting the parameter candidate value of the next variable parameter, the signal quality of each combination of parameter candidate values is good. Several combinations will be selected. The recording strategy adjuster 15 selects a parameter candidate value combination having the smallest error variance between the reproduction waveform and the reference reproduction waveform from among the parameter candidate value combinations selected last (step S150).

  Here, the variable parameters are the pulse width of the shortest mark (step S210), the recording power (step S220), the leading pulse width (step S230) and the final pulse width (step S240) of the mark 1T or longer than the shortest mark, cooling. The pulse widths (step S250) are set in this order, and parameter candidate values for each are obtained. This order is not fixed and may be changed as appropriate.

  For example, when setting the shortest mark pulse width (step S210), based on the basic pulse width obtained in the base strategy setting (step S100), the head pulse width corresponding to the shortest mark is set with the signal quality evaluation index being PRSNR. Ask. The pulse width at this time is set by changing the range from -0.06T to + 0.18T in steps of approximately 0.03T with the basic pulse width as the center. At each pulse width, a predetermined test pattern is recorded and reproduced, and a PRSNR indicating signal quality is calculated. The recording strategy adjuster 15 selects a pulse width having a good signal quality among the pulse widths as a parameter candidate value. The pulse width selected as the parameter candidate value is used as the shortest mark pulse width when the next variable parameter is measured.

  Next, when setting the recording power (step S220), the shortest mark pulse width is fixed to the value selected in the setting of the shortest mark pulse width (step S210), and the recording power (recording power and bias power) is set. Becomes a variable parameter. Each of the recording power and the bias power is set by changing the range of about ± 20% in 5% increments around the initial predetermined recording power. At each power value, a predetermined test pattern is recorded and reproduced, and a PRSNR indicating signal quality is calculated. The recording strategy adjuster 15 selects a power value having a good signal quality among the power values as a parameter candidate value. This power adjustment during recording is positioned as a fine adjustment of the recording strategy. The adjustment of the pulse width cannot be freely set due to restrictions in the recording / reproducing apparatus. However, the setting of the recording power is suitable for fine adjustment because the setting variable width can be made fine. Of the recording power thus obtained, the recording power value with good recording quality is selected as a parameter candidate value. Further, the recording power selected as the parameter candidate value is used as the recording power when the next variable parameter is measured. Note that the order of setting the pulse width of the shortest mark (step S210) and the setting of recording power (step S220) may be interchanged.

  Next, the width of the head pulse for recording a mark longer than the shortest mark by 1T (recording unit length) is set as the second head pulse width (step S230). For example, in the case of ETM modulation, the shortest mark has a length of 2T, the longest mark has a length of 13T, and the marks from 3T to 13T correspond to this. Of these mark lengths, leading pulse widths corresponding to 3T and 4T marks are obtained. Here, 4T or more marks are represented by 4T marks as one category, and the head pulse widths of the recording strategies corresponding to the 4T or more marks are all the same. The order of adjustment is the order of 3T mark and 4T mark, and the leading pulse width corresponding to the 3T mark and the leading pulse width corresponding to the 4T mark are sequentially determined based on the basic pulse width. The pulse width at this time is set in the range of -0.06T to + 0.18T in steps of approximately 0.03T with the basic pulse width as the center. This range is preferably set in advance. The pulse width is set by changing the position of the leading edge of each pulse. PRSNR is used as an evaluation index indicating the signal quality, and the recording strategy adjuster 15 selects the leading pulse width of the 3T mark and the leading pulse width of the 4T mark, which have good signal quality, as parameter candidate values. The leading pulse width selected as the parameter candidate value is set as the leading pulse width when the next variable parameter is measured.

  The adjustment order in the categories of the 3T mark and the 4T mark may be changed to the order of the 4T mark and the 3T mark. Further, it is not necessary to adjust any of the 3T mark and 4T mark categories. Further, the 4T mark category can be subdivided and adjusted with the 4T, 5T,..., 9T, 11T, and 13T mark categories. These are preferably set in consideration of the restriction of time spent for adjustment and the adjustment accuracy.

  Next, the pulse width of the final pulse of the mark formed on the optical disc 10 is set (step S240). Marks of 4T or more are grouped into one category and represented by 4T marks, and the final pulse width is adjusted. That is, the final pulse width of the recording strategy corresponding to the 4T or more mark is the same pulse width. Therefore, the trailing edge of the last pulse for recording the shortest mark (2T mark), 3T mark, and 4T mark is adjusted in order. As the final pulse width, a pulse width is set in which the range from -0.16T to + 0.18T is changed to about 0.03T with the basic pulse width as the center. A predetermined test pattern is recorded on and reproduced from the optical disc while changing the pulse width of the final pulse, and the signal quality is measured. PRSNR is used as an evaluation index indicating the signal quality at this time. The recording strategy adjuster 15 selects, as a parameter candidate value, the final pulse width when the signal quality is good based on the obtained signal quality. The final pulse width selected as the parameter candidate value is used as the final pulse width when the next variable parameter is measured.

  In the case of the (k-1) type pulse train, since the 2T mark is a pulse of only the first pulse, here, the edge (edge) of the pulse used when the shortest mark pulse width is set (step S210) Adjust the opposite edge. Alternatively, it is not necessary to adjust the final pulse width for the 2T mark of the (k-1) type pulse train. Moreover, the order of the categories of 2T, 3T, and 4T marks may be changed, and the order of 4T, 3T, and 2T marks may be adjusted. In addition, the adjustment of the trailing edge of the last pulse of the 3T and 4T marks may not be performed. Further, the 4T mark category may be subdivided and adjusted. Thus, the pulse width of the final pulse for mark recording is set appropriately.

  Next, the pulse width of the mark cooling pulse formed on the optical disc 10 is set (step S250). Marks of 4T or more are grouped into one category and represented by the 4T mark. The recording parameters for recording the 4T mark are used to adjust the width of the cooling pulse. . That is, the cooling pulse widths of the recording strategy corresponding to 4T or more marks are all set to the same pulse width. Therefore, the trailing edges of the cooling pulses of the shortest (2T) mark, 3T mark, and 4T mark are adjusted in order. The pulse width of the cooling pulse for each mark length is set in steps of approximately 0.03T from the state where there is no cooling pulse, that is, the state where the pulse width is zero to the pulse width of approximately 1.50T. A predetermined test pattern is recorded and reproduced on the optical disc 10 while changing the pulse width of the cooling pulse, and the signal quality is measured. PRSNR is used as an evaluation index indicating the signal quality at this time. The recording strategy adjuster 15 selects the cooling pulse width when the signal quality is good as a parameter candidate value based on the obtained signal quality. In setting the pulse width of the cooling pulse, the cooling pulse width for all mark lengths may be set as the same pulse width. Thus, the width of the cooling pulse for mark recording is set appropriately.

  As described above, the pulse width of each pulse is set. The variable range of each pulse, the step size, and the like are set so as to be selectable in consideration of the time restriction required for adjustment and the adjustment accuracy. The setting of the final pulse width (step S240) may be executed before the setting of the leading pulse width of the mark longer than the shortest mark (step S230), and after the setting of the recording power (step S220), the shortest pulse width is set. The final pulse width (step S240) may be set without setting the head pulse width of the mark longer than the mark (step S230). Further, in the process of sequentially selecting these variable parameters, when the signal quality exceeds the “assumed PRSNR value” set in the parameter table, the selection of the subsequent variable parameters may be canceled. That is, the omission of execution order and processing depends on the balance between the time required for adjustment and the adjustment accuracy.

  As described above, the variable parameters are sequentially set. A plurality of strategy parameter combinations can be made based on the parameter candidate values obtained in the process. The recording strategy adjuster 15 obtains an optimum combination of parameter values from among them. That is, among the combinations of the parameter values whose PRSNR exceeds a predetermined value as the signal quality, the variance value of the error between the reproduction waveform and the reference reproduction waveform is calculated for the combination of the top two strategy parameters having a particularly large PRSNR value. A set of strategy parameters having a small error variance value is selected as an optimum combination of parameter values.

  For example, in the setting of the cooling pulse width (step S250), a measurement result is obtained as shown in FIG. The measurement results when the cooling pulse width is around 0.6T show substantially the same signal quality. A combination of parameter candidate values for obtaining this measurement result is defined as a strategy parameter SET_A and a strategy parameter SET_B. A variance value of errors in the strategy parameter SET_A and the strategy parameter SET_B is calculated. FIG. 9 shows the calculated variance values, and it can be seen that the error variance value by the strategy parameter SET_A is smaller than the error variance value by the strategy parameter SET_B. Therefore, the recording strategy adjuster 15 selects a strategy parameter SET_A having a small variance value.

  Note that the variance value as the performance index after being extracted based on the predetermined evaluation index indicates the stability of each recorded mark or space. That is, the smaller the number of unstable elements including the mark shape and formation state, the smaller the dispersion value, which reflects the less variation.

  Here, as a comparative example, FIG. 10 shows a result of measuring the recording power margin by changing only the recording power while fixing the pulse width parameter in the recording strategy parameter SET_A and the recording strategy parameter SET_B. As shown in FIG. 10, the recording strategy parameter SET_A has a wider recording power margin and is suitable as a parameter.

  In addition, as described above, it is sufficient that the parameter setting accuracy can be set relatively freely. However, there are many cases where the parameter setting accuracy is limited, and in this case, the center of the parameter range that satisfies the predetermined performance is selected. There are things you can't do. Even in such a case, it is possible to select a recording strategy parameter with a wider margin at high speed.

  In the above description, the signal quality evaluation index in the step of setting each variable parameter (steps S210 to S250) has been described by exemplifying PRSNR. However, an error rate (synonymous with the number of errors) may be used as the signal quality evaluation index. .

  Next, an operation when an optical disk not assumed by the information recording / reproducing apparatus is loaded will be described. Although the disc manufacturing information including information such as the disc manufacturer name and the production location is held in the system information area of the optical disc 10, the optical disc is out of the expected range for the information recording / reproducing apparatus 1. Such a state may occur when an optical disk that has appeared after the information recording / reproducing apparatus is shipped to the market is loaded.

  In such a case, when the optical disc 10 is loaded, the information recording / reproducing apparatus 1 moves the optical head 20 to the system information area of the optical disc 10. The information recording / reproducing apparatus 1 reads Disc Manufacturing information including information such as the disc manufacturer name and production location from the system area, and acquires the disc type, disc manufacturer name, and the like. Based on these pieces of information, the information recording / reproducing apparatus 1 determines that the optical disc 10 is a single-layer HD DVD-R medium. However, since the information recording / reproducing apparatus 1 does not include a parameter table relating to this medium, the recording strategy adjuster 15 sets a base strategy by setting a predetermined recording power value and pulse width. Thereafter, as described above, the recording strategy adjuster 15 selects each strategy parameter candidate value and obtains an optimum set of recording strategy parameters.

  In the setting of the head pulse width corresponding to the shortest mark (step 210), the recording strategy adjuster 15 performs selection by performing test recording while changing the pulse width within a predetermined range based on the basic pulse width. . This may be set as the top pulse width corresponding to the shortest mark by multiplying the basic pulse width by a predetermined coefficient. Since the top pulse width corresponding to the shortest mark is set without performing trial recording, it is possible to obtain good recording conditions at higher speed even in HD DVD using PRML detection.

  Even if a medium that does not exist at the time when the information recording / reproducing apparatus 1 is shipped is loaded, the recording strategy can be adjusted with high accuracy. That is, even if the information recording / reproducing apparatus 1 is a medium that does not have information, it can be easily adjusted and is an effective method.

  As described above, the method for obtaining the candidate value for each variable parameter and finally selecting the best set of recording strategy parameters by the variance value has been described. However, when the candidate value for each variable parameter is selected, the variance value is selected. It is also possible to select based on The method will be described below.

  FIG. 11 shows a flowchart of the recording strategy adjustment operation of the information recording / reproducing apparatus 1. The operation of the recording strategy adjuster 15 will be described below with reference to FIG.

  When the optical disk 10 is loaded in the information recording / reproducing apparatus 1, the system controller 5 moves the optical head unit 20 to the system information area and reads Disc Manufacturing information. Based on the information, the type of the disk, the disk manufacturer name, etc. To get. The system controller 5 acquires a parameter table relating to the medium, and sets an initial value of the base strategy based on the parameter table. A predetermined test pattern is trial-recorded on the optical disc, and the recording strategy adjuster 15 sets a base strategy based on the signal quality (PRSNR) (step S100).

  Based on the base strategy, the recording strategy adjuster 15 sequentially adjusts each variable parameter such as the pulse width of the shortest mark, the power during recording, the leading pulse width, the final pulse width, and the cooling pulse width as shown in FIG. To do. That is, the recording strategy adjuster 15 first sets the variable range and step size of the variable parameter (step S110). When the variable range and step size are set, trial recording is performed using each variable value, and the signal quality is measured (step S120).

  In step S130 for selecting a variable parameter candidate value, the method of candidate selection is changed here depending on the value of the measured evaluation index. That is, the recording strategy adjuster 15 determines whether or not the measured signal quality has reached a predetermined signal quality (step S132). When there are a plurality of measurement values that have better signal quality than the predetermined signal quality (step S132-OK), the recording strategy adjuster 15 performs error dispersion between the reproduction waveform output from the variance calculator 48 and the reference reproduction waveform. Based on this, a parameter candidate value is selected. That is, the recording strategy adjuster 15 selects, as parameter candidate values, parameter values having the smallest error variance among the parameter values that have obtained good signal quality (step S134). On the other hand, when none of the measured values has reached the predetermined signal quality (step S132NG), the recording strategy adjuster 15 selects the parameter value that is the best among the measured values as the parameter candidate value (step S136). ). The selected parameter value is used instead of the base strategy parameter when determining the next variable parameter. Note that a plurality of values may be selected as the parameter candidate values.

  Steps S110 to S130 are repeated while changing the variable parameters in the order shown in FIG. Therefore, the parameter candidate values of the variable parameters are combined, and the recording strategy adjuster 15 obtains the parameter value candidates while gradually improving the signal quality (step S140).

  When the parameter candidate values for all the variable parameters are obtained, the recording strategy adjuster 15 obtains the optimum combination of parameter values among them. That is, since the parameter candidate value of each variable parameter is selected and the value is used when selecting the parameter candidate value of the next variable parameter, the signal quality of each combination of parameter candidate values is good. Several combinations will be selected. The recording strategy adjuster 15 selects a parameter candidate value combination having the smallest error variance between the reproduction waveform and the reference reproduction waveform from among the parameter candidate value combinations selected last (step S150).

  As described above, in the method described above, the parameter candidate value is selected based on the value of the measured signal quality evaluation index. Here, however, the recording strategy adjuster 15 has a good measured signal quality. If so, a parameter value having a small error variance between the reproduction waveform and the reference reproduction waveform is selected. Therefore, better signal quality can be expected.

  Here, for each variable parameter, the method for selecting parameter candidate values is switched according to the measured signal quality, but it may be switched only when a specific variable parameter is selected. When all the variable parameters are selected based on the signal quality value, the above-described candidate selection is performed.

  When selecting a parameter candidate value based on the measured signal quality value, it is preferable to select a parameter value having the best signal quality value in the parameter change range. When a plurality of measurement values having a predetermined signal quality or higher are obtained, the parameter value closest to the average value of the parameter values corresponding to the measurement values may be selected. Alternatively, the median value of the parameter values may be selected as the parameter candidate value. The parameter value selected by the average value or the median value is not necessarily the best parameter value at this point, but approaches the best parameter value by adjusting the variable parameter thereafter. When there are many measured values that are equal to or higher than a predetermined signal quality, it is preferable to select a parameter value for obtaining an average value (median value) according to the number of increments of the variable parameter value, that is, the number of variable ranges divided by the increment. .

  Further, the value of the predetermined signal quality in step S132 may be constant, but is preferably set in association with the variable parameter and the order of adjustment. That is, when PRSNR is used as the signal quality evaluation index, it is preferable that the required signal quality is set higher each time the adjustment step proceeds as shown in FIG. FIG. 13 shows set values when the signal quality evaluation index is an error rate. The signal quality evaluation index may be only one of PRSNR and error rate, but may be changed for each variable parameter or used in combination.

  Since the measured value of the signal quality varies greatly depending on the performance of the information recording / reproducing apparatus 1 and the performance of the optical disc 10, the information recording / reproducing apparatus 1 aborts the adjustment when the signal quality satisfies the condition, and executes Step S150. You may operate | move so that the optimal parameter set in the stage may be calculated | required. In other words, the recording strategy adjuster 15 may operate so as to select the variable parameter in consideration of the time limit for adjustment and the adjustment accuracy.

  In the above description, a low-to-high medium has been exemplified as the optical disc 10, but the present invention is not limited to a low-to-high medium, and can be applied to a high-to-low medium. Further, in the optical head unit 20, the present invention is applicable to any wavelength and NA without being limited to the wavelength 405nm and NA (numerical aperture) 0.65. Further, in the above-described embodiment, the adaptive equalizer 37 has been described as using the class PR (12221). However, other classes such as PR (1221) can be used as well. Further, although ETM adopted in HD DVD is assumed as a modulation code, other modulation codes can be used similarly. In this case, for example, the shortest data length such as kT (k is a natural number of 3 or more) may change. Further, the present invention can be applied not only to HD DVD but also to a Blu-ray disc (Blu-ray disc).

  As described above, the selection effect can be enhanced and the recording strategy parameter can be determined at high speed by using the configuration in an appropriate situation in consideration of the characteristics of the evaluation index itself.

  In the present invention, on the premise that a predetermined performance according to a predetermined index is satisfied, the one having a small total error variance in the amplitude direction (meaning that the pattern is not distinguished) is selected. The present invention is characterized in that it has been found that error variance can be effectively utilized under the above assumption.

  In particular, it is not necessary to calculate the variance divided into individual patterns. Also, it is not always the best quality that the error variance in the amplitude direction corresponding to all marks or spaces is small. For example, even if the error variance at a level corresponding to a certain mark is small, if the level itself deviates from the assumed level, the performance may be degraded in PRML detection. Also, when marks recorded with different parameters are compared, in a reproduced signal of a mark recorded with each parameter, the magnitude of dispersion is reversed at a certain level, depending on the parameter, among a plurality of assumed detection levels. However, the total variance including other levels may be small.

  Thus, the true optimum parameter does not simply indicate the best parameter on the evaluation scale at the time of selection. A parameter that secures a predetermined signal quality and has a wide margin for fluctuation is a true optimum parameter. In the present invention, for a pulse width condition that is extracted under a condition that satisfies a predetermined signal quality without selecting a parameter that is used until margin measurement comparison (margin check), the parameter condition The final recording strategy parameter is selected according to the variance value of the error between the reproduced waveform showing variation and the ideal reproduced waveform. Therefore, according to the present invention, the recording strategy parameter can be adjusted at high speed. In addition, since trial recording and reproduction including a margin check is not performed, the adjustment area of the optical disk need not be used unnecessarily.

  Further, in the present invention, the recording strategy parameter condition is extracted by an index indicating that recording and reproduction can be performed so that a reproduction waveform by continuous marks and spaces can be assumed as a response. From the plurality of extracted recording strategy parameters, a recording strategy parameter is selected using an index mainly based on the degree of variation obtained from a reproduced waveform obtained by reproducing a recorded pattern sequence. By using different indexes for each purpose, the selection effect is improved. Therefore, recording strategy parameter adjustment with high reliability can be performed. In addition, the calculation of variation uses an arithmetic expression with a relatively small calculation load, and the sequential variance is calculated in accordance with the number of samples. Therefore, a high-speed response can be expected, which is suitable for apparatus and hardware.

  ADVANTAGE OF THE INVENTION According to this invention, the signal recording condition adjustment method and information recording / reproducing apparatus to the optical information recording medium which adjust a recording strategy parameter at high speed can be provided. Further, since the trial recording / reproducing including the margin check is not performed, the adjustment area is not wasted.

  In addition, according to the present invention, it is possible to provide a method for adjusting a signal recording condition on an optical information recording medium and an information recording / reproducing apparatus that adjust recording strategy parameters with high reliability.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  In addition, this application claims the priority based on the Japanese application number 2007-201701, and the disclosed content in the Japanese application number 2007-201701 is incorporated into this application by reference.

Claims (30)

Based on a recording strategy including a plurality of adjustable parameters, a value of the plurality of parameters is set to a predetermined value, and a first parameter selected from the plurality of parameters in a predetermined order is set as a variable parameter. Steps,
Irradiating the optical information recording medium with intensity-modulated laser light while changing the value of the variable parameter within a predetermined range, and test recording a pattern row having a mark portion and a space portion;
Replaying the test-recorded pattern sequence and measuring a signal quality value indicating reproduction signal quality corresponding to each value of the variable parameter;
Selecting a parameter candidate value from each value of the variable parameter based on the signal quality value;
The replacement plurality of values of the parameters selected parameter candidate values of the parameters before Symbol parameter candidate value, and generating a combination of multiple parameter values,
The variable parameter is sequentially changed to the parameter that is not selected as the parameter candidate value of the plurality of parameters in the predetermined order, the test recording step, the measuring step, and the parameter candidate value are selected. and repeating the step, and a step of generating a pre-Symbol set only combination that,
After the repetition, the combination of the parameter candidate values that minimizes the variance value of the error between the reproduced signal waveform reproduced from the pattern string and the reference reproduced waveform calculated based on the pattern string is selected as the optimum value. And a method for adjusting signal recording conditions on an optical information recording medium. The reference reproduction waveform is a waveform indicated by a pattern string used for recording.
A method for adjusting signal recording conditions on an optical information recording medium according to claim 1. The reference reproduction waveform is a waveform indicated by an estimated data sequence generated by a discriminator based on the reproduction signal waveform.
A method for adjusting signal recording conditions on an optical information recording medium according to claim 1. The variance is σ ² , the difference between the playback waveform data obtained by digitizing the playback signal waveform and the reference waveform data indicating the reference playback waveform calculated based on the pattern sequence is an error Xk, and the variance is When the number of samples of the error included in the obtained period is N (N is an integer equal to or greater than 1), the variance σ ² is an average of the square sum of the error Xk and an average square sum of the error Xk. Using,

Calculated by the following formula
The method for adjusting a signal recording condition to the optical information recording medium according to any one of claims 1 to 3. The recording strategy is a pulse train type recording strategy for recording the mark portion by a plurality of pulses,
The plurality of pulses are:
A heating pulse including a first pulse output first in the mark portion, a final pulse output last in the mark portion, and an intermediate pulse connected between the first pulse and the last pulse;
5. A method for adjusting a signal recording condition on an optical information recording medium according to claim 1 . The plurality of parameters include a pulse width of the plurality of pulses.
6. A method for adjusting signal recording conditions on an optical information recording medium according to claim 5. When k is a natural number of 2 or more and T is a channel clock period,
The pulse train type recording strategy in which the length of a mark portion to be recorded is kT includes k−1 pulse groups.
Signal recording condition adjusting method of the optical information recording medium according to claim 5 or claim 6. The plurality of parameters include recording power and bias power of the plurality of pulses.
8. A method for adjusting signal recording conditions on an optical information recording medium according to claim 5. The step of selecting the parameter candidate value includes the step of selecting, as the parameter candidate value, the value of the variable parameter corresponding to the signal quality value that is higher in the signal quality value measured in the measuring step.
The method for adjusting signal recording conditions on an optical information recording medium according to claim 1 . The step of selecting the parameter candidate value selects, as the parameter candidate value, the value of the variable parameter corresponding to the signal quality value that exceeds a predetermined threshold among the signal quality values measured in the measuring step. With steps
The method for adjusting signal recording conditions on an optical information recording medium according to claim 1 . The step of selecting the parameter candidate value is associated with each of the plurality of parameters,
The value of the variable parameter corresponding to the signal quality value that is higher in the signal quality value measured in the measuring step;
Alternatively, the method includes the step of switching the variable parameter value corresponding to the signal quality value that exceeds a predetermined threshold among the signal quality values measured in the measuring step and selecting the value as the parameter candidate value.
The method for adjusting signal recording conditions on an optical information recording medium according to claim 1 . In the step of selecting the parameter candidate value, when the signal quality value exceeds a predetermined value, a value of the variable parameter that minimizes a variance value of an error between the reproduction signal waveform and the reference reproduction waveform is set to the parameter The step of selecting as a candidate value is further provided
12. A method for adjusting signal recording conditions on an optical information recording medium according to claim 9. The signal quality value is indicated by PRSNR
The method for adjusting a signal recording condition to an optical information recording medium according to any one of claims 1 to 12. The quality evaluation value is indicated by an error rate.
The method for adjusting a signal recording condition to an optical information recording medium according to any one of claims 1 to 12. The signal quality value is indicated by a PRSNR or an error rate set in association with each of the plurality of parameters.
The method for adjusting a signal recording condition to an optical information recording medium according to any one of claims 1 to 12. Based on a recording strategy including a plurality of adjustable parameters, an optical information recording medium is irradiated with intensity-modulated laser light while changing a variable parameter value of the plurality of parameters within a predetermined range. An optical head unit that test records a pattern row having a mark portion and a space portion, reads the pattern row recorded on the optical information recording medium, and outputs an electrical signal;
Reproduction means for generating a reproduction waveform signal based on the electrical signal;
A signal quality calculation means for measuring a signal quality value indicating a reproduction signal quality of the reproduction waveform signal corresponding to each value of the variable parameter based on the reproduction waveform signal;
Selects a plurality of parameter candidate values from among the values of the variable parameters based on the signal quality value, the value of the parameter the selected parameter candidate value of the plurality of parameters to the parameter candidate value replacement, comprising a recording strategy adjustment means for generating a combination of multiple parameter values,
The recording strategy adjusting means sequentially changes the variable parameter to a parameter in which the parameter candidate value of the plurality of parameters is not selected in a predetermined order, and performs the test recording, measurement of the signal quality value, and the parameter. Based on the result of repeating the selection of candidate values, the parameter candidate value of the parameter candidate value that minimizes the variance value of the error between the reproduced signal waveform reproduced from the pattern string and the reference reproduced waveform calculated based on the pattern string. An information recording / reproducing apparatus that selects a combination to obtain an adjustment result of signal recording conditions. Furthermore, it comprises storage means for storing the pattern sequence to be recorded for trial,
The waveform indicated by the pattern sequence used for the test recording and stored in the storage means is used as the reference reproduction waveform.
The information recording / reproducing apparatus according to claim 16. The reproducing means includes a discriminator that estimates the pattern sequence recorded based on the reproduction signal waveform and outputs an estimated data sequence,
The waveform indicated by the estimated data string output from the discriminator is set as the reference reproduction waveform.
The information recording / reproducing apparatus according to claim 16. The variance is σ ² , the difference between the playback waveform data obtained by digitizing the playback signal waveform and the reference waveform data indicating the reference playback waveform calculated based on the pattern sequence is an error Xk, and the variance is When the number of samples of the error included in the obtained period is N (N is an integer equal to or greater than 1), the variance σ ² is an average of the square sum of the error Xk and an average square sum of the error Xk. Using,

Calculated by the following formula
Information recording and reproducing apparatus according to claim 18 claim 16. The recording strategy is a pulse train type recording strategy for recording the mark portion by a plurality of pulses,
The plurality of pulses are:
A heating pulse including a first pulse output first in the mark portion, a final pulse output last in the mark portion, and an intermediate pulse connected between the first pulse and the last pulse;
Information recording and reproducing apparatus according to claims 16 to claim 19. The plurality of parameters include a pulse width of the plurality of pulses.
The information recording / reproducing apparatus according to claim 20. When k is a natural number of 2 or more and T is a channel clock period,
The pulse train type recording strategy in which the length of a mark portion to be recorded is kT includes k−1 pulse groups.
Information recording and reproducing apparatus according to claim 20 or claim 21. The plurality of parameters include recording power and bias power of the plurality of pulses.
Information recording and reproducing apparatus according to claim 22 claim 16. The recording strategy adjusting unit selects, as the parameter candidate value, the value of the variable parameter corresponding to the signal quality value in which the measured signal quality value is higher.
Information recording and reproducing apparatus according to claims 16 to claim 23. The recording strategy adjustment unit selects, as the parameter candidate value, the value of the variable parameter corresponding to the signal quality value that exceeds a predetermined threshold among the measured signal quality values.
Information recording and reproducing apparatus according to claims 16 to claim 23. The recording strategy adjustment means is associated with each of the plurality of parameters,
The value of the variable parameter corresponding to the signal quality value where the measured signal quality value is higher,
Alternatively, the variable parameter value corresponding to the signal quality value exceeding a predetermined threshold among the measured signal quality values is switched and selected as the parameter candidate value
Information recording and reproducing apparatus according to claims 16 to claim 23. The recording strategy adjusting unit further determines the parameter candidate value to be a value of the variable parameter that minimizes a variance value of an error between the reproduction signal waveform and the reference reproduction waveform when the signal quality value exceeds a predetermined value. Select as value
27. The information recording / reproducing apparatus according to claim 24. The signal quality value is indicated by PRSNR
Information recording and reproducing apparatus according to claim 27 claim 16. The quality evaluation value is indicated by an error rate.
Information recording and reproducing apparatus according to claim 27 claim 16. The signal quality value is indicated by a PRSNR or an error rate set in association with each of the plurality of parameters.
Information recording and reproducing apparatus according to claim 27 claim 16.

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