JP2009070434A - Method for correcting recording condition and optical disk unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk unit which can correct recording parameters while recording user data when a temperature, disk characteristic, and a linear speed change and which does not lower a recording rate substantially. <P>SOLUTION: A method for correcting the recording parameters for recording on an optical disk with a constant angular velocity stops recording temporarily when the linear speed changes by a preset value while recording, and measures asymmetry of a reproducing signal of a recording area right before stopping to update setting of a recording power based on the result of the asymmetry measurement. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording method and a recording / reproducing apparatus for recording digital information on a recording medium, and more particularly, to control recording conditions so that an ideal mark is formed on the recording medium even when the linear velocity changes. The present invention relates to a method for correcting CAV recordable recording conditions and an optical disc apparatus.

  In a general optical disk apparatus, a reproduction clock included in a reproduction signal is extracted by a PLL circuit, and based on the reproduction clock extracted from the reproduction signal, the original digital information is “1” or “0”. A binarization method for discriminating whether or not by a comparator is widely used.

  FIG. 1 shows a configuration diagram of a conventional optical disc apparatus. The reflected light from the optical disk 1 is converted into a reproduction signal by the optical head 2. The reproduction signal is waveform-shaped by the waveform equalizer 3, and the waveform-shaped reproduction signal is binarized by the comparator 4. The threshold value of the comparator 4 is normally feedback controlled so that the integration result of the binarized output becomes zero. The phase comparator 5 obtains a phase error between the binarized output and the recovered clock. The phase error is averaged by the LPF 6 to become the control voltage of the VCO 7 and feedback control is applied so that the phase error output from the phase comparator 5 is always zero.

  In the case of the binarization method as described above, the synchronized data is “1” or “0” depending on whether the output of the comparator 4 is within the detection window width (window width) of the recovered clock. Judging.

  In addition, with the development of short wavelength lasers, the capacity of optical disks is also increasing. A DVD with a wavelength of about 650 nm has a recording capacity of 4.7 GB on one side and a single layer, but a so-called next-generation DVD of Blu-Ray disc and HD-DVD disc having the same diameter has a capacity of 15 GB or more. In order to realize this large capacity, reproduction technology that reads data correctly from small recording marks, signals with degraded signal quality such as low S / N and intersymbol interference, and stable recording of small recording marks on recording media Recording technology to form is required.

  One playback technology that supports the realization of large-capacity optical disks is PRML signal processing. In order to increase the capacity, it is indispensable to increase the linear recording density, and the stability of the optical disk apparatus is improved by using a RLL code with a shorter shortest mark as the recording code and using a wider detection window. However, if this is done, a smaller recording mark will be formed on the recording medium, and intersymbol interference from adjacent marks (or spaces) will increase. In the conventional binarization method, such intersymbol interference has been removed by a waveform shaping circuit, but PRML signal processing that actively uses this intersymbol interference is also used in recent optical disc apparatuses. Yes.

  The recording technology that realizes a large-capacity optical disk is laser power control and adaptive mark compensation. In an rewritable and additionally writable optical disk, a recording mark is formed by giving a change in film thickness to the recording film by light (heat) irradiated from a laser on the disk.

  Usually, the film structure and recording film composition of the disk are optimized on the assumption that the recording film is recorded at a constant linear velocity. In the case of a DVD single-layer disc, the standard speed is 3.49 m / sec, and at 16 times speed, it is 55.8 m / sec. Available speeds are specified for commercially available discs. However, even for a disc optimized in a predetermined recording speed range, the longer the laser light irradiation time, the higher the temperature of the recording film and the longer the mark formed due to heat conduction on the optical disc. . Laser power control controls the current value of the laser diode during recording, and adaptive mark compensation controls the shape of the mark formed by changing the length and position of the recording pulse according to the recording pattern.

FIG. 2 shows an example of a recording pulse, and shows a pulse shape in the case of recording a 2T (T is a recording clock width) length mark, a 3T length mark, and an 8T length mark. Parameters for controlling the recording power include a recording power level P _W , a space power level P _S , a bias power level P _BW , and a cooling power level P _C. Parameters for controlling the position of the recording pulse train include T _top indicating the width of the leading pulse, dT _top indicating the position, T _mp indicating the multi-pulse width, T _lp indicating the end pulse width, and dT _s indicating the position of the cooling pulse. There is.

  By changing these parameters in accordance with the recording pattern, it is possible to control the amount of heat applied and stably form minute marks on the disc. Such a recording pulse control method is called adaptive mark compensation. The material used for the disc includes an inorganic material and an organic polymer material, and the composition, composition, and structure of the recording film vary depending on the manufacturer even if the material is the same. The amount of heat required for irradiation varies depending on the recording speed. Therefore, the recommended recording parameters are recorded in advance on the disk for each recording speed, and the optical disk apparatus can read out the recording parameters to form an optimum recording mark.

  However, even if the parameters recommended by the disc manufacturer are used, there are variations in the device and disc characteristics, the ambient temperature in which the optical disc device is used, the usage status of the disc (if it is a rewritable disc, is it an unrecorded disc? There is no guarantee that the recommended parameters of the manufacturer are optimal depending on whether the disc has been recorded or overwritten many times, etc.) Therefore, trial recording is generally performed on recordable and write once optical discs, and an area where trial recording can be performed is secured on the inner or outer periphery of the disc.

  When a disc is loaded in the optical disc apparatus, the disc information recorded in advance on the disc is read, initial recording parameters are set, test recording is performed using the initial recording parameters in the test recording area, and the recording parameters are optimized. Do. Then, user data is recorded using the obtained optimum parameter data.

  For example, in Patent Document 1, the mark length and the space length are classified into three or four types, and the deviation amount of the start and end positions of the mark is detected for each combination pattern of the mark and space, and the deviation amount is reduced. Thus, there is shown a method of adjusting the recording pulse and controlling the start and end positions of the mark formed on the recording medium so that the jitter of the reproduction signal is below a certain value. Specifically, using the phase error output of the phase comparator 5 of the optical disc apparatus as shown in FIG. 1, the start and end positions of the mark are adjusted so that the phase error is minimized.

  An optical disk apparatus using PRML processing has started to be provided in place of a conventional general optical disk apparatus. In the optical disk apparatus of FIG. 1, the quality of the reproduced signal is evaluated by measuring the output of the comparator 4 and the time interval (jitter) of the VCO 7. However, PRML processing generally performs maximum likelihood decoding using the Viterbi algorithm, and the correlation between the jitter and the maximum likelihood decoding result becomes poor. Therefore, a reproduction signal suitable for an optical disc apparatus newly using PRML processing is used. An evaluation method is provided.

  The Viterbi algorithm selects a path that is more certain (the sum of squares of the distance between the expected value and the reproduced waveform is smaller) from the two possible paths from the metric calculation result. For example, in Patent Document 2, a difference between two metric operations is set as a difference metric, and if the difference metric is much larger than 0 or small, one of the two paths is surely selected. If the metric is close to 0, it means that the selection is not strange regardless of which one is selected. It can be said that the former has high signal quality and the latter has poor signal quality. If the above-mentioned difference metric is integrated for each combination pattern of marks and spaces using this, it can be understood which pattern degrades the signal quality on average. In other words, it is possible to detect the deviation amount of the start and end positions of the mark. By adjusting the recording parameters so as to reduce this deviation amount, it is possible to form a recording mark suitable for PRML processing on the medium.

Patent Document 3 shows that it is possible to adjust power and strategy using a PR equalization method that allows more intersymbol interference and using PRSNR and asymmetry as indices. Furthermore, as the timing for adjusting the recording parameters described above, when the rotational speed of the optical disk device changes, when a temperature change occurs, when a certain amount of recording operation is performed, when a recording operation is performed for a certain period of time, or servo There are cases where the parameter exceeds the allowable value.
Japanese Patent No. 3076033 JP 2004-335079 A JP 2005-339690 A

  However, even in the recent optical disc apparatus using the PRML process, the recording condition may change even if the recording parameter optimized by the above-described method is used. For example, the recording conditions can be changed in the following three cases.

  First, the temperature of the optical disk device and the temperature of the disk may change. This occurs because the temperature inside the apparatus changes due to the heat radiation of the optical disk apparatus itself and the ambient temperature.

  Second, the characteristics of the disk change. For example, since the recording film has a thickness of only a nanometer, if the thickness of the recording film changes between the inner periphery and the outer periphery, it is necessary to adjust the amount of heat applied.

  In the first case, every time the temperature of the apparatus changes by a predetermined value, recording of user data is interrupted, recording parameters are optimized again in the test recording area, and user data is recorded again.

In the second case, the user data recording is interrupted every time a predetermined length recording or a predetermined length area recording on the disk radius, the recording parameters are optimized in the test recording area, and the user data is recorded again. Make a record. In the case of a rewritable disc, the recording parameters can be optimized relatively many times by overwriting the trial recording area. However, in the case of a write once type disc, the trial recording area is used one after another. Frequently, the recording parameters cannot be optimized.

  In the third case, the transfer rate has been increased in recent years, and an optical disc apparatus capable of reading data at a speed of 52 times or higher for a CD and 16 times or higher of a DVD has been realized. Similarly, the recording speed is increasing. Rewritable and write-once optical discs must be recorded under the condition of constant linear velocity (constant linear velocity, hereinafter referred to as CLV), so that the rotational speed of the disc on the inner circumference is 10,000 rpm or more, making control difficult. In addition, it is necessary to change the rotational speed of the disk by about 2.4 times between the inner and outer circumferences of the disk, and the motor reaches the desired rotational speed as the speed difference between the inner and outer circumferences increases as the speed increases. As a result, the stability and access performance of the optical disc apparatus are problematic. Therefore, a method of recording the disk at a constant angular velocity (hereinafter, referred to as CAV) is employed. In the CAV method, since the disk rotation speed is constant, a difference of two times or more occurs between the linear velocity on the inner peripheral side and the outer peripheral side. Since the amount of heat required for recording also changes depending on the linear velocity, it is necessary to optimize the recording parameters according to the linear velocity. However, if the recording parameters are frequently optimized, there is a problem that the recording rate is lowered.

  In the method disclosed in Patent Document 3, PRSNR or asymmetry suitable for PRML processing is measured and the power and strategy are adjusted. However, the difference between the target PRSNR and the measurement result depends on the strategy factor. In such a case, in order to perform adaptive mark compensation, there is a problem that it is impossible to determine which mark / space combination pattern is the main cause.

  Further, in the conventional optical disk apparatus, in order to adjust the recording power and strategy, the recording area is reproduced, the asymmetry is measured, and the recording parameter is corrected from the measurement result. However, depending on the CPU of the optical disk apparatus, there is a problem that a certain time is required even when the apparatus performs recording at a high speed and the recording rate is lowered.

  The present invention has been made to solve the above-described conventional problems. Even when temperature, disk characteristics, and linear velocity change while recording user data, adaptive recording parameter correction is performed. An object of the present invention is to provide an optical disc apparatus using PRML signal processing that can be performed.

  An optical disk using PRML signal processing that does not cause a substantial decrease in recording rate when correcting recording parameters when temperature, disk characteristics, and linear velocity change while recording user data. An object is to provide an apparatus.

  In order to solve the above problems, a recording parameter correction method according to claim 1 of the present invention is a recording parameter correction method in which recording is performed on an optical disk with a constant angular velocity. When the change is quantitative, recording is temporarily stopped, the asymmetry amount of the reproduction signal in the recording area immediately before the stop is measured, and the recording power setting is updated from the measurement result of the asymmetry amount.

  As a result, even when there is a change in linear velocity during data recording, adaptive recording power correction can be performed, and appropriate recording can be performed.

  The recording parameter correction method according to claim 2 of the present invention is a recording parameter correction method for recording on an optical disc with a constant angular velocity, and when the linear velocity changes during recording, The recording is temporarily stopped, the edge shift amount of the reproduction signal in the recording area immediately before the stop is measured, and the recording strategy setting is updated from the measurement result of the edge shift amount.

  As a result, even when the linear velocity changes during data recording, adaptive recording strategy correction can be performed, and appropriate recording can be performed.

  The recording parameter correction method according to claim 3 of the present invention is a recording parameter correction method for recording on an optical disc with a constant angular velocity, and when the linear velocity changes during recording by a predetermined amount, Recording is temporarily stopped, and the edge shift amount and asymmetry amount of the reproduction signal in the recording area immediately before the stop are measured. If the detected asymmetry amount is within the range of the reference value, the measurement result of the edge shift amount is used. The recording strategy setting is updated, and if the detected asymmetry amount is outside the range of the reference value, the recording power setting is updated from the measurement result of the asymmetry amount.

  As a result, even when the linear velocity changes during data recording, adaptive recording power correction and recording strategy correction can be performed, and appropriate recording can be performed.

  A recording parameter correction method according to claim 4 of the present invention is the recording parameter correction method according to claim 1, wherein after the measurement of the asymmetry amount of the reproduction signal is completed, the temporarily stopped recording is resumed. While performing the recording operation, the recording power correction calculation is performed from the measurement result of the asymmetry amount, the recording power setting is updated based on the recording power correction calculation result, and the recording operation is continued with the updated recording power. It is characterized by.

  As a result, even when there is a change in linear velocity during data recording, adaptive recording power correction can be performed, and a substantial decrease in recording rate can be prevented. Can be performed.

  The recording parameter correction method according to claim 5 of the present invention is the recording parameter correction method according to claim 2, wherein after the measurement of the edge shift amount of the reproduction signal is completed, the temporarily stopped recording is resumed. While performing the recording operation, the recording strategy correction calculation is performed from the edge shift amount measurement result, the recording strategy setting is updated based on the recording strategy correction calculation result, and the recording operation is continued with the updated recording strategy. It is characterized by that.

  As a result, even when there is a change in linear velocity during data recording, adaptive recording strategy correction can be performed, and a substantial decrease in recording rate can be prevented. Can be performed.

  A recording parameter correction method according to claim 6 of the present invention is the recording parameter correction method according to claim 3, wherein after the measurement of the edge shift amount and the asymmetry amount of the reproduction signal is completed, the temporarily stopped recording is performed. If the detected asymmetry amount is within the range of the reference value, the recording strategy correction calculation is performed based on the measurement result of the edge shift amount while performing the recording operation, and the recording strategy correction calculation is performed. Based on the result, the recording strategy setting is updated, and if the detected asymmetry amount is outside the range of the reference value, the recording power correction calculation is performed based on the measurement result of the asymmetry amount while performing the recording operation. The recording power setting is updated based on the recording power correction calculation result, and the updated recording strategy and recording power are recorded. Characterized in that it continues to operate.

  As a result, even when there is a change in linear velocity during data recording, adaptive recording power correction and recording strategy correction can be performed, and a substantial decrease in recording rate can be prevented. And appropriate recording can be performed.

  The optical disk apparatus according to claim 7 of the present invention is an optical disk apparatus for recording on an optical disk with a constant angular velocity, and when the linear velocity changes during recording, the recording is temporarily stopped and immediately before the stop. The asymmetry amount of the reproduction signal in the recording area is measured, and the recording power setting is updated from the measurement result of the asymmetry amount.

  As a result, even when there is a change in linear velocity during data recording, adaptive recording power correction can be performed, and appropriate recording can be performed.

  An optical disk apparatus according to an eighth aspect of the present invention is an optical disk apparatus that records on an optical disk with a constant angular velocity, and temporarily stops recording when the linear velocity changes by a predetermined amount during recording. The edge shift amount of the reproduction signal in the recording area is measured, and the recording strategy setting is updated from the measurement result of the edge shift amount.

  As a result, even when the linear velocity changes during data recording, adaptive recording strategy correction can be performed, and appropriate recording can be performed.

  An optical disk apparatus according to claim 9 of the present invention is an optical disk apparatus that records on an optical disk with a constant angular velocity, and temporarily stops recording when the linear velocity changes by a predetermined amount during recording. Measuring the edge shift amount and the asymmetry amount of the reproduction signal in the recording area of the recording area, and if the detected asymmetry amount is within a reference value range, the setting of the recording strategy is updated from the measurement result of the edge shift amount, If the detected asymmetry amount is outside the range of the reference value, the recording power setting is updated from the measurement result of the asymmetry amount.

  As a result, even when the linear velocity changes during data recording, adaptive recording power correction and recording strategy correction can be performed, and appropriate recording can be performed.

  An optical disc apparatus according to a tenth aspect of the present invention is the optical disc apparatus according to the seventh aspect, wherein a PLL circuit for extracting a clock included in the reproduction signal and a reproduction signal are sampled by the clock extracted by the PLL circuit. An asymmetry detection circuit for outputting an asymmetry amount of the reproduction signal from the reproduction signal converted into a digital signal by the A / D converter, and an asymmetry amount output from the asymmetry detection circuit are held A storage means, an optical disc controller that corrects recording power from the asymmetry amount held in the storage means and updates a recording parameter at the next recording time, and a recording pulse based on the recording parameter information output from the optical disc controller And a recording condition setting circuit for determining a shape.

  As a result, even when there is a change in linear velocity during data recording, adaptive recording power correction can be performed, and appropriate recording can be performed.

  An optical disk apparatus according to an eleventh aspect of the present invention is the optical disk apparatus according to the eighth aspect, wherein a PLL circuit that extracts a clock included in the reproduction signal and a reproduction signal is sampled by the clock extracted by the PLL circuit. An A / D converter, a digital filter that adaptively updates filter characteristics so that a reproduction signal digitalized by the A / D converter becomes a predetermined PR equalization output, and PR equalization by the digital filter A Viterbi circuit that performs maximum likelihood decoding from the reproduced signal, a pattern detection circuit that detects a start edge and a termination edge of a specific recording mark from the binarized data output from the Viterbi circuit, and an output from the digital filter From the reproduction signal and the specific pattern detection information output from the pattern detection circuit, the quality information of the reproduction signal is obtained. A signal quality evaluation circuit that outputs, an edge shift detection circuit that obtains an average edge shift amount for each of the start edge and the end edge of the specific recording mark from the signal quality information from the signal quality evaluation circuit, and the edge shift Storage means for holding the edge shift amount output from the detection circuit, and an optical disk for finding out the parameter to be optimized from the edge shift amount held in the storage means, correcting it, and updating the recording parameter at the next recording And a recording condition setting circuit for determining a recording pulse shape based on the recording parameter information output from the optical disk controller.

  As a result, even when the linear velocity changes during data recording, adaptive recording strategy correction can be performed, and appropriate recording can be performed.

  According to the present invention, even when the linear velocity changes during data recording, adaptive recording parameter correction can be performed while recording user data, and reliability is ensured on the premise of PRML processing. High recording marks can be formed on the recording medium. Further, even when the recording parameters are frequently corrected during high-speed recording, an effect that no substantial decrease in the recording rate occurs can be obtained.

(Embodiment 1)
Hereinafter, an optical disk device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 3 is a diagram showing a configuration of the optical disc apparatus 100 according to the first embodiment.

  The optical disc apparatus 100 records recording data at a predetermined address on the optical disc 8 during a recording operation. The optical disk controller 9 performs initial setting of recording parameters in the recording compensation circuit 10. The recording compensation circuit 10 generates a recording pulse signal using recording data and an initially set recording parameter. As a recording parameter, it is also possible to use a parameter obtained by reading a parameter recorded in advance on the optical disc 8.

  In the recording pattern used in the first embodiment, when an error correction code is added to user data and recording modulation is performed, for example, 4T mark 3T space, 4T mark 4T space, 4T mark 5T space,. 4m4s, 4m5s, etc.), and a plurality of sets of mark length and space length, which are different from each other. More specifically, in order to perform adaptive mark compensation, a recording parameter can be set for every combination of mark length and space length. For example, a mark of 5T or more and a space of 5T or more can be set. The combination can simplify the setting of complicated recording parameters by using the same recording parameters. In the above example, in addition to a combination of a mark of 5T or more and a space of 5T or more, a 4m3s group, a 4m4s group, a 4m5s group, and the like are included. In the first embodiment, as shown in FIGS. 4 and 5, all the recording parameters (for example, 32 types) set for each set of mark length and space length can be optimized. .

  The laser drive circuit 11 drives a laser diode in the optical head in accordance with a recording pulse signal, and irradiates the optical disk 8 with laser light to record data. A so-called adaptive mark compensation method is employed, and a plurality of marks and spaces having different lengths are formed on the optical disc 8 corresponding to the data to be recorded. In order to optimize each recording parameter, the data recorded on the optical disc 8 is reproduced, and the suitability of the recording parameter is determined from the obtained reproduction signal. During the reproducing operation, the reproducing laser beam is irradiated onto the optical disc 8 from the optical head. The reflected light from the optical disk 8 is converted into an electrical signal (reproduced signal) in the optical head. An AGC (Automatic Gain Controller) 12 controls the amplitude of the reproduction signal so that the amplitude of the waveform-shaped reproduction signal is constant. The output signal from the AGC 12 is waveform-shaped by the waveform equalizer 13. The waveform-shaped reproduction signal is sampled and quantized by an analog-to-digital converter (A / D converter) 14, whereby data having a multilevel level is converted from the A / D converter 14 into a digital signal. Is output as The sampling frequency in the A / D converter 14 is set based on an output (reproduced clock signal) from a PLL (Phase Locked Loop) 15 that is feedback-controlled as will be described later. Specifically, the PLL circuit 15 performs feedback control so that the phase error between the reproduction signal and the reproduction clock signal approaches 0 as a whole. In this way, a reproduction clock signal synchronized with the reproduction signal is generated from the reproduction signal.

  The output signal of the A / D converter 14 is input to the digital filter 16. The digital filter 16 can change the frequency characteristic according to the input signal so that the output signal of the A / D converter 14 becomes predetermined PR equalization. A predetermined PR equalized reproduction signal is input to the Viterbi circuit 17. The Viterbi circuit 17 performs maximum likelihood decoding on the predetermined PR-equalized reproduction signal according to the recording data modulation rule and the state transition rule determined from the PR equalization characteristic, and outputs binary data.

  The pattern detection circuit 18 detects whether the binarized data output from the Viterbi circuit 17 includes a combination pattern of mark length and space length classified as shown in FIGS. 4 and 5, for example. For example, when a pattern having a self mark length of 4T and a preceding space length of 3T is detected, a detection flag indicating 3s4m is output to the signal quality evaluation circuit 19. The signal quality evaluation circuit 19 obtains a differential metric calculated by the Viterbi algorithm from the PR equalized signal from the digital filter 16 and determines the reliability when one path is selected from two possible paths. Ask. Whether the selected result is a combination of the mark length and the space length shown in FIGS. 4 and 5 is determined based on the input signal from the pattern detection circuit 18. Information about which pattern is the pattern in FIGS. 4 and 5 and the reliability of the detected pattern are output to the edge shift detection circuit 20.

  Based on the detection pattern information from the signal quality evaluation circuit 19, the edge shift detection circuit 20 determines the reliability information average value and variation (standard) for each combination of mark length and space length. (Deviation). The average value indicates the amount by which the edge of the recording mark formed with the current recording parameters is constantly deviated from the ideal mark position. The average value of the detected reliability information is called an edge shift amount. The obtained edge shift amount and standard deviation are output to the DRAM 22.

  On the other hand, the asymmetry detection circuit 21 obtains the asymmetry (asymmetry) of the reproduction signal from the output of the A / D converter, and outputs the detection result to the DRAM 22. A specific configuration of the asymmetry detection circuit is shown in FIG. Using a threshold value determined from an output of a peak envelope voltage detection circuit 23 for detecting the upper maximum value of the reproduction signal, a bottom envelope voltage detection circuit 24 for detecting the lower minimum value, and an integration circuit 26 described later, A comparator 25 for binarizing the reproduction signal, an integration circuit 26 for obtaining the center voltage of the reproduction signal from the output result of the comparator 25, a peak envelope voltage detection circuit 23, and a bottom envelope voltage detection circuit for detecting the lower minimum value 24 and an asymmetry detection circuit 27 for obtaining the asymmetry amount of the reproduction signal from the output of the integration circuit 26.

  FIG. 7 shows an example of an asymmetry waveform. Asymmetry can be calculated using [Equation 1] from the detected peak envelope voltage Vp, bottom envelope voltage Vb, and center voltage Vc of the reproduction signal. it can.

  The asymmetry detection circuit 21 outputs the obtained asymmetry amount to the DRAM 22. The optical disk controller 9 corrects a recording parameter related to a strategy, which will be described later, using an average value of reliability information for each combination of mark length and space length held in the DRAM 22. Further, based on the amount of asymmetry held in the DRAM 22, a recording parameter relating to power, which will be described later, is corrected.

  Next, a series of recording parameter correction operations in the optical disc apparatus 100 according to the first embodiment will be described. FIG. 8 is a diagram showing the flow of the recording parameter correction process.

  First, when a command is issued to perform a recording operation to the optical disc apparatus 100, the optical disc controller 9 learns recording parameters (step S100). Normally, test recording areas are secured on the inner and outer circumferences of the optical disc, and learning of the recording parameters is often performed at the start-up when an unrecorded disc is loaded.

  Next, initial recording parameters are set (step S101). This sets the value obtained by the recording parameter learning (S100). Alternatively, a value recorded in advance on the optical disc is set. Alternatively, a recording parameter value may be set by reading a history when recording on the same optical disk. In addition, a target asymmetry amount for adjusting the recording power is set in advance. Note that the processing procedures S100 and S101 may be performed at the time of activation, not when a recording command is issued.

  Next, data recording is performed (step S102), and then the process proceeds to recording end determination (step S103).

  In the recording end determination S103, it is determined whether or not the recording of the length specified by the recording command has ended. If the amount of recorded data is small, the status of the optical disk or the apparatus is unlikely to change. Therefore, in the recording end determination S103, the process branches to an end process, but when the amount of recorded data is large, the next status change occurs. Conceivable. That is, (1) when the temperature in the optical disk device changes, (2) when the characteristics of the recording film of the optical disk change depending on the disk radius (or when continuous recording of a predetermined length is performed), and (3) CAV recording If the linear velocity changes to perform If any of these three changes occur, recording is interrupted (step S104). Thereafter, the recording parameters before the recording interruption are held (step S105).

  Next, the reproduction operation is started. In this reproduction operation, the area recorded before the interruption is reproduced, and the asymmetry amount and the edge shift amount are measured from the reproduction signal (step S106). Then, a deviation amount between the detected asymmetry amount and the target asymmetry set value is obtained, and if the difference is within the reference value, the process branches to the recording strategy correction process, and if the difference is outside the reference value, the process branches to the recording power correction process (step) S107).

  If the asymmetry amount is outside the reference value, the recording power correction calculation is performed from the previous recording power and the detected asymmetry amount (step S108). Details of the recording power correction calculation S108 will be described later. Thereafter, the updated recording power is set or the recording power value before the recording interruption is set (step S109), and then the process returns to step S102 to resume the recording.

  On the other hand, if the asymmetry amount is within the reference value, based on the detected edge shift amount, if the detected shift amount is greater than or equal to the reference value, the corresponding recording parameter is determined based on the previous recording strategy and the detected edge shift amount. Correction calculation is performed (step S110). If it is within the reference value, the recording strategy correction processing is not performed. Details of the recording strategy correction calculation S110 will be described later. Thereafter, the updated recording strategy is set, or the recording strategy value before the recording interruption is set (step S111), and the recording is resumed.

  At the end of recording, the recording parameters before the end are acquired (step S112). The acquired recording parameter is used for setting an initial recording parameter (step S101) when the next recording command is issued.

  Next, details of the recording power correction calculation (S108) will be described with reference to FIGS.

  FIG. 9 shows an example of the relationship between the recording power Pw and the asymmetry amount, in which the recording power Pw is plotted on the horizontal axis and the asymmetry amount detected on the vertical axis. The detected asymmetry amount increases almost monotonously with respect to the recording power Pw. When linear approximation is performed, the gradient g becomes a conversion coefficient between asymmetry amount and power. For such an inclination, a coefficient obtained by recording parameter learning (S100) can be used, or a conversion coefficient may be obtained from information recorded in advance on a disc.

  FIG. 10 shows a procedure for correcting the recording power from the conversion coefficient and the detected asymmetry amount.

  First, a difference Δasym between the asymmetry target value (asym_target) and the asymmetry measurement value (asymmetry) is obtained (step S150). Next, it is determined whether or not Δasym is within a predetermined range (step S151). If Δasym is within a predetermined range, it is determined that power correction is unnecessary, and the recording power before the recording interruption is used when recording is resumed (S153). On the other hand, if Δasym is out of the predetermined range, the recording power Pw is corrected according to the following formula [Equation 2] (step S152).

  Here, Pw, n is the recording power before correction, Pw, n + 1 is the recording power after correction, and W is the weight of the correction calculation. W is a positive number equal to or less than 1, and an appropriate value is set so that excessive power correction is not performed.

  Next, it is determined whether or not the corrected recording power exceeds the upper limit value (step S154). If the upper limit is not exceeded, Pw, n + 1 is used as the recording power after resuming recording (step S155). On the other hand, if the upper limit value is exceeded, the upper limit value is used as the recording power after resuming recording (step S156).

  In the first embodiment, the example in which the recording power is corrected using the relationship between the asymmetry amount and the recording power has been described. However, the same correction can be performed by using the modulation degree and the β value instead of the asymmetry amount. Processing can be performed.

  Next, details of the recording strategy correction calculation (step S110) will be described with reference to FIGS. 11, 12, 13, and 14. FIG.

  FIG. 11 shows a recording pulse shape when a recording pattern of 2Ts3Tm is written. In FIG. 11, the recording strategy setting value is positive when the starting edge changes in the positive direction (right side in FIG. 11) in the time axis direction.

When dT _top is changed positively, the start edge of the recording mark moves to the right, and the formed 3T mark length is shortened. Conversely, when dT _top is changed to a negative value, the start edge of the recording mark moves to the left, and the formed 3T mark becomes longer. The edge shift amount output from the edge shift detection circuit 20 is 0 when dT _top is 0, and becomes a normal distribution having a standard deviation σ in an ideal case. When dT _top is positive, the edge shift amount is a normal distribution having a negative value. Conversely, when dT _top is negative, the edge shift amount is a normal distribution having a positive value. Note that the direction in which the recording mark increases is the positive direction.

FIG. 12 shows the edge shift amount detected when the dT _top that determines the mark start end position of the recording pulse is changed. As shown in FIG. 12, the detected edge shift amount monotonously decreases with respect to the recording strategy dT _top . If the recording strategy dT _top is corrected so that the detected edge shift amount becomes 0, the recording strategy can be optimized.

  FIG. 13 shows a recording pulse shape when a 3Tm3Ts recording pattern is written. In FIG. 13, when the end edge changes in the positive direction (to the right in FIG. 13) in the time axis direction, the recording strategy setting value is positive.

  When Tlp is changed positively, the end edge of the recording mark moves in the right direction, and the formed 3T mark becomes longer. Conversely, when Tlp is changed negatively, the end edge of the recording mark moves to the left, and the length of the formed 3T mark is shortened. The edge shift amount output from the edge shift detection circuit 20 is 0 when Tlp is 0, and becomes a normal distribution having a standard deviation σ in an ideal case. When Tlp is positive, the edge shift amount is a normal distribution having a positive value. Conversely, when Tlp is negative, the edge shift amount is a normal distribution having a negative value.

FIG. 14 shows the amount of edge shift detected when Tlp for determining the mark start end position of the recording pulse is changed. As shown in FIG. 14, the detected edge shift amount monotonously increases with respect to the recording strategy Tlp. If the edge shift amount detected similarly to the recording strategy dT _top corrected write strategy Tlp so that 0, it is possible to optimize the recording strategy.

  As shown in FIGS. 12 and 14, since there is a monotonous change relationship between the recording strategy and the edge shift amount, the slope g is a conversion coefficient between the edge shift amount and the recording strategy when linearly approximated similarly to the asymmetry amount. It becomes. For such an inclination, a coefficient obtained by recording parameter learning (step S100) can be used, or a conversion coefficient set in advance in the optical disc apparatus may be used.

  FIG. 15 is a diagram illustrating a procedure for performing a recording strategy correction process at the mark start end from the conversion coefficient and the detected edge shift amount.

  First, it is determined whether or not Δedgeshift is within a predetermined range for all combinations of mark length and space length (step S161). If Δedgeshift is within the predetermined range, it is determined that strategy correction is unnecessary and recording is performed. When resuming, the recording strategy before the recording interruption is used (step S163). On the other hand, if Δedgeshift is out of the predetermined range, the recording strategy dTtop is corrected according to the following formula [Equation 3] (step S162).

  Here, dTtop, n is a recording strategy before correction, dTtop, n + 1 is a recording strategy after correction, and W is a weight of correction calculation. W is a positive number equal to or less than 1, and an appropriate value is set so as not to perform excessive strategy correction.

  Next, it is determined whether or not the corrected recording strategy exceeds the upper limit value and the lower limit value (step S164). If it is within the predetermined range, dTtop, n + 1 is used as the recording strategy after resuming recording (step S165). On the other hand, if it exceeds the predetermined range, the upper limit value or the lower limit value is used as the recording strategy after resuming recording (step S166).

  FIG. 16 is a diagram showing a processing procedure for correcting the recording strategy at the end of the mark from the conversion coefficient and the detected edge shift amount, as in the recording strategy correcting process at the start of the mark. The recording strategy correction at the end of the mark is substantially the same as the recording strategy correction processing at the mark start end according to FIG. 15, but since the sign of the conversion coefficient is the reverse of the case of the start edge, the sign in equation [3] is also inverted. It is necessary to use the following formula [Equation 4].

Here, Tlp, n is the recording strategy before correction, Tlp, n + 1 is the corrected recording strategy, and W is the weight of the correction calculation. In the first embodiment, the example in which the recording strategy is corrected using the relationship between the edge shift amount, the recording strategy dT _top , and Tlp is shown. However, instead of dT _top and Tlp, Ttop, Ttmp are used. , DTs can be used to perform the same correction process.

  17 and 18 are diagrams showing examples of detection results of edge shift amounts.

  FIG. 17 shows the distribution of the edge shift amount on the mark start end side. In FIG. 17, the center of the 3Ts4Tm distribution is shifted, and the edge shift amount takes a negative value. Other mark start positions indicate correct results. In the first embodiment, the recording strategy of 3Ts4Tm is corrected so as to be smaller than the current value by the mathematical formula [Equation 3]. As a result, the start position of the recording pulse is controlled so that the mark length becomes longer.

  FIG. 18 shows the distribution of the edge shift amount on the mark end side. In FIG. 18, the center of 5Tm3Ts is shifted and the edge shift amount is a positive value. Other mark start positions indicate correct results. In the first embodiment, the recording strategy of 5Tm3Ts is corrected so as to be smaller than the current value by the mathematical formula [Equation 4]. As a result, the recording pulse end position is controlled so that the mark length is shortened.

  Next, the execution timing of the recording parameter correction operation in the optical disc apparatus 100 of the first embodiment will be described.

  FIG. 19 shows a timing chart when the recording parameter correction processing procedure shown in FIG. 8 is performed.

  When a recording command is issued, a recording operation is performed in units of a predetermined length. After that, (1) when the temperature in the optical disk device changes, (2) when the characteristics of the recording film of the optical disk changes depending on the disk radius, (3) when the linear velocity changes because of CAV recording, etc. When a change occurs, recording is interrupted and recording parameter correction processing is performed.

  In the correction processing, first, asymmetry measurement and edge shift measurement are performed, and then the recording power and recording strategy correction processing is performed based on the detected asymmetry amount and edge shift amount. After updating the recording power and the recording strategy, the recording is resumed. When the environmental change of the optical disk apparatus occurs again, the recording is interrupted and the recording parameters are corrected. When the necessary data recording is completed, the recording is ended, and the recording parameters immediately before the end are held for the next recording operation.

  Here, when the optical disc apparatus performs recording at the standard speed, the time required for the calculation process of the recording parameter correction is not dominant among the processing time required for the recording operation. However, when the optical disc apparatus performs high-speed recording, the time for recording the unit length or the time for reproducing (measuring) the unit length is shortened depending on the recording speed and the playback speed. However, since the time required for the correction process depends on the processing capability of the CPU of the optical disk device, the same time is required even if the optical disk device is at a high speed. Therefore, if the recording parameter correction is frequently performed, the effective recording rate is lowered.

  Therefore, in the optical disc apparatus 100 according to the first embodiment, as shown in FIG. 20, during high-speed recording, when the recording parameter is corrected, the interruption process is advanced by the time required for the calculation process in advance. That is, recording is temporarily interrupted as early as the time required for the arithmetic processing, the immediately preceding recording area is reproduced, the asymmetry amount and the edge shift amount are measured, and recording is resumed. On the other hand, recording parameter correction processing is performed simultaneously with recording from the measurement result. When the calculation process is completed, the recording parameter is corrected, and the recording operation is continued using the updated recording parameter. By simultaneously performing the calculation process and the recording operation in this way, the time required for the correction process can be shortened, and a decrease in the recording rate can be substantially prevented.

  In FIG. 20, when the recording parameter is corrected, the interruption process is advanced in advance by the time required for the calculation process. However, the interruption process is not advanced, but the recording area is reproduced once after the recording operation is completed. Then, the asymmetry amount and the edge shift amount are measured, and the next recording is performed. Simultaneously with the recording, a recording parameter correction process is performed from the measurement result. When the arithmetic processing is completed, the same effect as described above can be obtained even when the recording is interrupted, the recording parameters are corrected, and the recording operation is restarted using the updated recording parameters.

  As described above, according to the optical disk apparatus of the first embodiment, when temperature, disk characteristics, and linear velocity change, recording is temporarily stopped, reproduction signal asymmetry of the recording area immediately before the stop, and edge shift Since the recording parameter is updated according to the measurement result and the data recording is continuously performed with the updated recording parameter, the temperature, the disk characteristics, the linear velocity are recorded during the user data recording. Even when the change occurs, adaptive recording parameter correction can be performed, and a highly reliable recording mark can be formed on the recording medium on the premise of PRML processing.

  Also, the recording is temporarily stopped, the edge shift amount and the asymmetry amount of the reproduction signal in the recording area immediately before the stop are measured, the recording is resumed after the measurement is completed, and the detected edge shift amount and the asymmetry amount are performed while performing the recording operation. Based on the above, the recording strategy correction calculation and the recording power correction calculation are performed. When the calculation result is obtained, the recording parameter setting is updated, and the recording operation is continued with the updated recording parameter. Even when the recording parameters are frequently corrected, a highly reliable recording mark can be formed on the recording medium, and a reduction in effective recording rate can be prevented.

  The optical disk reproducing apparatus and the recording parameter correction method for recording at a constant angular velocity according to the present invention are useful in that the recording power and the recording strategy can be corrected while minimizing the decrease in the recording rate. Further, the present invention can be applied not only to a rewritable type or a write once type optical disk apparatus that performs CAV recording, but also to an optical disk apparatus that performs CLV recording, and it is also possible to perform correction processing of a reproduction parameter with the same configuration. It is also useful for a recording / reproducing apparatus for a magnetic recording medium such as a magnetic disk.

It is a figure which shows the structure of the conventional optical disk apparatus. It is a figure which shows the example of the recording pulse of a rewritable type and a write once optical disc apparatus. 1 is a configuration diagram of an optical disc device 100 according to Embodiment 1 of the present invention. FIG. FIG. 6 is a diagram illustrating a first classification example of a recording strategy set for each set of mark length and space length in the first embodiment. FIG. 10 is a diagram illustrating a second classification example of a recording strategy set for each set of mark length and space length in the first embodiment. FIG. 2 is a configuration diagram of an asymmetry detection circuit 21 in the disk device of the first embodiment. It is a figure which shows the example of an asymmetry waveform. FIG. 3 is a flowchart showing a recording parameter correction operation process in the first embodiment. It is a figure which shows the relationship between recording power and the amount of asymmetry. FIG. 3 is a flowchart showing a recording power correction process in the first embodiment. FIG. 3 is a recording pulse shape diagram when writing a 2Ts3Tm recording pattern in the first embodiment. FIG. 6 is a diagram illustrating an edge shift amount detected when a recording parameter at a mark start edge is changed in the first embodiment. FIG. 3 is a recording pulse shape diagram in the case of writing a 3Tm3Ts recording pattern in the first embodiment. FIG. 6 is a diagram illustrating an edge shift amount detected when a recording parameter at a mark end is changed in the first embodiment. FIG. 6 is a flowchart showing a recording strategy correction process at the start of a mark in the first embodiment. FIG. 6 is a flowchart showing a recording strategy correction process at the end of a mark in the first embodiment. FIG. 6 is a diagram showing a detection result of an edge shift amount on the mark start end side in the first embodiment. FIG. 6 is a diagram showing a detection result of an edge shift amount on the mark end side in the first embodiment. 4 is a timing chart when performing a recording parameter correction process in the first embodiment. 4 is a timing chart in the case of simultaneously performing a recording parameter correction process and a recording operation during high-speed recording in the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical disk apparatus 1, 8 Optical disk 2 Optical head 3, 13 Waveform equalizer 4, 25 Comparator 5 Phase comparator 6 LPF
7 VCO
9 Optical disk controller 10 Recording compensation circuit 11 Laser drive circuit 12 AGC
14 A / D converter 15 PLL circuit 16 Digital filter 17 Viterbi circuit 18 Pattern detection circuit 19 Signal quality evaluation circuit 20 Edge shift detection circuit 21 Asymmetry detection circuit 22 DRAM
23 Peak-side envelope voltage detection circuit 24 Bottom-side envelope voltage detection circuit 26 Integration circuit S100 Recording parameter learning S101 Target asymmetry setting, initial recording parameter setting S102 Recording S103 Recording end determination S104 Recording interruption determination S105 Recording parameter acquisition before recording interruption S106 Asymmetry measurement , Edge shift measurement S107 asymmetry reference value determination S108 recording power correction calculation S109 recording power setting S110 recording strategy correction calculation S111 recording strategy setting S112 acquisition of recording parameter before recording S150 difference calculation between asymmetry target value and measurement value S151 necessity of power correction processing Determination S152 Recording power correction calculation S153 Recording power setting before recording interruption S154 Recording power correction value abnormality determination S155 Recording power correction value Set to recording power S156 Set recording power upper limit to recording power S161, S171 Determination of necessity of recording strategy correction processing S162 Recording strategy correction calculation (mark start side)
S163, S173 Recording strategy setting before recording interruption S164, S174 Recording strategy correction value abnormality determination S165, S175 Set recording strategy correction value to recording strategy S166, S176 Set recording strategy upper / lower limit value to recording strategy S172 Recording strategy correction calculation ( Mark end side)

Claims (11)

A method for correcting a recording parameter when recording on an optical disk with a constant angular velocity,
If the linear velocity changes during recording, stop recording temporarily,
Measure the amount of asymmetry of the playback signal in the recording area just before the stop,
Update the recording power setting from the measurement result of the asymmetry amount,
And a recording parameter correction method. A method for correcting a recording parameter when recording on an optical disk with a constant angular velocity,
If the linear velocity changes during recording, stop recording temporarily,
Measure the edge shift amount of the playback signal in the recording area just before the stop,
Update the recording strategy setting from the measurement result of the edge shift amount,
And a recording parameter correction method. A method for correcting a recording parameter when recording on an optical disk with a constant angular velocity,
If the linear velocity changes during recording, stop recording temporarily,
Measure the edge shift amount and asymmetry amount of the playback signal in the recording area just before the stop,
If the detected asymmetry amount is within the range of the reference value, the setting of the recording strategy is updated from the measurement result of the edge shift amount. If the detected asymmetry amount is outside the range of the reference value, the asymmetry is updated. Update the recording power setting from the amount measurement result,
And a recording parameter correction method. The method for correcting a recording parameter according to claim 1,
After the measurement of the amount of asymmetry of the reproduction signal is completed, the paused recording is resumed,
While performing the recording operation, the recording power is corrected from the asymmetry measurement result,
Based on the correction calculation result of the recording power, update the recording power setting,
Continue recording with the updated recording power.
And a recording parameter correction method. The method for correcting a recording parameter according to claim 2,
After the measurement of the edge shift amount of the reproduction signal is completed, the paused recording is resumed,
While performing the recording operation, perform the correction calculation of the recording strategy from the measurement result of the edge shift amount,
Update the recording strategy setting based on the correction calculation result of the recording strategy,
Continue the recording operation with the updated recording strategy.
And a recording parameter correction method. The method for correcting a recording parameter according to claim 3,
After the measurement of the edge shift amount and the asymmetry amount of the reproduction signal, the paused recording is resumed,
If the detected asymmetry amount is within the range of the reference value, the recording strategy is corrected based on the measurement result of the edge shift amount while performing the recording operation, and based on the correction calculation result of the recording strategy , Update the recording strategy settings,
If the detected asymmetry amount is outside the range of the reference value, while performing the recording operation, based on the measurement result of the asymmetry amount, the recording power correction calculation is performed, and based on the recording power correction calculation result, Update the recording power setting,
Continue the recording operation with the updated recording strategy and recording power.
And a recording parameter correction method. An optical disc apparatus for recording on an optical disc with a constant angular velocity,
When the linear velocity changes during recording, the recording is temporarily stopped, the asymmetry amount of the reproduction signal in the recording area immediately before the stop is measured, and the recording power setting is updated from the measurement result of the asymmetry amount.
An optical disc device characterized by the above. An optical disc apparatus for recording on an optical disc with a constant angular velocity,
When the linear velocity changes during recording, the recording is temporarily stopped, the edge shift amount of the reproduction signal in the recording area immediately before the stop is measured, and the recording strategy setting is updated from the measurement result of the edge shift amount.
An optical disc device characterized by the above. An optical disc apparatus for recording on an optical disc with a constant angular velocity,
When the linear velocity changes during recording, the recording is temporarily stopped, the edge shift amount and the asymmetry amount of the reproduction signal in the recording area immediately before the stop are measured, and the detected asymmetry amount is within the reference value range. If it is within, the recording strategy setting is updated from the measurement result of the edge shift amount, and if the detected asymmetry amount is outside the range of the reference value, the recording power setting is updated from the measurement result of the asymmetry amount. To
An optical disc device characterized by the above. The optical disk apparatus according to claim 7,
A PLL circuit for extracting a clock included in the reproduction signal;
An A / D converter that samples the reproduction signal with the clock extracted by the PLL circuit;
An asymmetry detection circuit for outputting an asymmetry amount of the reproduction signal from the reproduction signal converted into a digital signal by the A / D converter;
Storage means for holding the amount of asymmetry output from the asymmetry detection circuit;
An optical disk controller that corrects the recording power from the asymmetry amount held in the storage means, and updates the recording parameters at the next recording;
A recording condition setting circuit for determining a recording pulse shape based on recording parameter information output from the optical disk controller,
An optical disc device characterized by the above. The optical disc apparatus according to claim 8, wherein
A PLL circuit for extracting a clock included in the reproduction signal;
An A / D converter that samples the reproduction signal with the clock extracted by the PLL circuit;
A digital filter that adaptively updates a filter characteristic so that a reproduction signal digitalized by the A / D converter becomes a predetermined PR equalized output;
A Viterbi circuit that performs maximum likelihood decoding from a reproduction signal PR-equalized by the digital filter;
A pattern detection circuit for detecting the start edge and the end edge of the specific recording mark from the binarized data output from the Viterbi circuit;
A signal quality evaluation circuit for outputting reproduction signal quality information from the reproduction signal output from the digital filter and the specific pattern detection information output from the pattern detection circuit;
From the signal quality information from the signal quality evaluation circuit, an edge shift detection circuit for obtaining an average edge shift amount for each start edge and end edge of the specific recording mark;
Storage means for holding an edge shift amount output from the edge shift detection circuit;
An optical disk controller that finds a parameter to be optimized from the edge shift amount held in the storage means, corrects the parameter, and updates the recording parameter at the next recording;
A recording condition setting circuit for determining a recording pulse shape based on recording parameter information output from the optical disk controller,
An optical disc device characterized by the above.

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