JPWO2008133133A1 - Signal recording condition adjusting method for optical information recording medium, information recording / reproducing apparatus - Google Patents

Abstract

The signal recording condition adjusting method includes a previous stage strategy setting step and a trailing edge adjusting step corresponding to the subsequent space length. In the previous strategy setting step, a recording strategy corresponding to the mark length is set without depending on the immediately preceding space length and the immediately following space length. In the trailing edge adjustment step corresponding to the subsequent space length, the trailing edge falling edge position of the recording strategy set in the preceding strategy setting step is adjusted based on the immediately following space length. This trailing edge adjustment step corresponding to the following space length is a uniform after changing the trailing edge falling edge position of the recording strategy corresponding to the mark having a mark length greater than or equal to a predetermined length by the same amount based on the immediately following space length. An edge adjustment step.

Description

The present invention relates to a signal recording condition adjusting method for recording information on an optical information recording medium, and an information recording / reproducing apparatus for recording information by the adjusting method.
Note that the content of Japanese Patent Application No. 2007-107608, which is the basic application of the present application, is incorporated into the present application by the disclosure of this application number.

  An optical disk apparatus is an apparatus that records information on an optical disk and 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, the control of the amount of irradiation light includes control of the output level such as recording power and bias power, and control of the pulse width and pulse position (time direction) of the laser pulse. This is called a recording strategy.

  As shown in FIG. 1A to FIG. 1C and FIG. 2A to FIG. 2C, there are various types of recording strategies, and the output level and pulse shape differ depending on the recording medium. For example, DVD-R (Digital Versatile Disc-Recordable), which is a recordable optical disc that can be recorded only once, has a rectangular (sometimes referred to as non-multi) recording strategy as shown in FIGS. 1A to 1C. Used. FIG. 1A shows a simple rectangular recording strategy, FIG. 1B shows a rectangular recording strategy with an emphasis on the beginning, and FIG. 1C shows a rectangular recording strategy with an emphasis on the beginning and the end. In a DVD-RW (DVD-ReWriteable) that is a rewritable optical disk that can be rewritten repeatedly, a multi-pulse type recording strategy as shown in FIGS. 2A to 2C is used. The output level in the space where no recording mark is formed is called bias power in a write once type (write-once type) optical disc, and it has an effect of erasing previously recorded recording marks in a rewritable type optical disc. Called. FIG. 2A shows a pulse train type (multi-pulse type) (basic type) recording strategy consisting of binary power levels, and FIG. 2B shows the recording power of each pulse train type pulse in three independent values, a total of 4 FIG. 2C shows a pulse train type recording strategy consisting of ternary power levels.

  In the case of HD DVD (High Density DVD), which is the next-generation DVD that has begun to be shipped in recent years, both the recordable HD DVD-R and the rewritable HD DVD-RW or HD DVD-RAM have a multi-pulse recording strategy. Mainly used. However, which recording strategy is used is not limited depending on the design of the drive, and therefore, a rectangular strategy can also be used in the recordable HD DVD.

  Here, the mark formation on the optical disc will be described. In an optical disk, a recording mark is formed by locally heating a recording film using a laser beam condensed on a rotating disk. The heat applied to record the leading edge of the mark diffuses and affects the recording of the trailing edge of the mark. In particular, the thermal diffusion is in the rear part of the mark where the thermal diffusion and the scanning direction of the light beam coincide. Accumulation occurs. Accordingly, heat accumulation due to thermal diffusion becomes more prominent behind the formation mark. Depending on the film structure and layer structure of the medium, depending on the combination of the size of the mark to be formed and the space length before and after it, the amount of heat accumulated in heat diffusion and the heat conductivity will vary, so there are various recording marks. Distortion (so-called nonlinear distortion) occurs. It is known that this non-linear distortion becomes prominent particularly in the case of a write-once type medium and high linear velocity recording.

  The recording strategy greatly affects the recording / reproducing performance of the optical disc. For this reason, many recording methods (recording strategies) and adjustment methods for recording strategies have been devised, and there are many reports. In particular, in addition to the recording mark itself, there is a recording strategy including a combination with a space before or after the recording mark.

  Japanese Patent Laid-Open No. 2005-32295 describes a recording method for switching a recording strategy depending on a medium. As a recording strategy, a timing parameter determined by a combination of the mark currently being recorded and the length of the space preceding the mark is prepared at the leading edge of the head pulse. For the trailing edge of the final pulse, a timing parameter determined by a combination of the mark and the length of the space following the mark is prepared. Combinations of parameters that are changed by various combinations of the leading and trailing edges of the first pulse and the last pulse are used as eight modes, and are switched depending on the medium. Also, in International Publication WO2002 / 084653, a relatively simple pattern sequence is used to measure the edge shift amount for each set of mark length and space length, and the recording parameters are updated so that the edge shift is reduced. It is stated that

  As another recording strategy adjustment method, the technique disclosed in Japanese Patent Application Laid-Open No. 2000-182244 assigns several levels to recording power and recording strategy parameters, and performs exhaustive experiments for each combination. This is an adjustment method for selecting the optimum one. Japanese Patent Application Laid-Open No. 2000-30254 describes an adjustment method in which adjustment of recording strategy parameters and adjustment of recording power are performed separately, and the recording power is determined using a theoretical mark length as a guideline.

  Japanese Patent Application Publication No. 2001-511289 discloses parameters that affect only the leading edge or only the trailing edge by measuring the leading edge jitter and trailing edge jitter from the reproduced signal in the test recording and reproduction (individual power of recording strategy constituent pulses and An adjustment method is described in which a leading edge jitter and a trailing edge jitter are separately determined by adjusting a combination of waveform shapes and the like. However, which edge of which pulse should be moved, even if it is power, for example, it is vague whether it is the power of all pulses or the power of individual pulses, and which adjustment should be given priority Not shown. When all the combinations are combined, there are too many combinations, and it is difficult to adjust the optimum recording strategy at high speed.

  Japanese Patent Application Laid-Open No. 2001-155340 describes a technique that can be applied to CAV, ZCAV, or CLV recording at an arbitrary speed and performs recording with a simple control method. This technique is based on the light emission pattern and pulse length setting optimized at the maximum linear velocity that can be set when forming a recording mark on an optical recording medium having a variable recording linear velocity by the multi-pulse method. A recording power is assigned to each pulse type for a pulse train for forming a recording mark, so that the pulse train is generated by two or more different recording powers. Each recording power is controlled in accordance with the recording linear velocity or the recording position of the optical recording medium. By controlling the recording power according to the recording linear velocity or recording position as in this technology, even if the emission pulse length of the recording strategy is fixed, low jitter can be realized at a linear velocity within the practical range. It has been. However, there is no mention of how to adjust.

  Japanese Laid-Open Patent Publication No. 2003-203343 discloses a CD-R and DVD-R recording strategy adjustment method, but since a plurality of combinations of a top pulse and a multi-pulse are required, high-speed adjustment is difficult. . Also, since there is no explanation of where to adjust to what extent, actual application is difficult. Japanese Patent Laid-Open No. 2005-216347 discloses a DVD-R recording strategy adjustment method.

  In the next-generation optical disc (HD DVD and BD: Blu-ray) with higher density, reading and writing are performed on the disc using laser light (short wavelength laser) having a light source wavelength of about 400 to 410 nm. The recording layer of the write-once optical disc currently developed for such a short wavelength laser can be broadly classified into those using inorganic materials and those using organic dye materials. A write-once medium using an inorganic material and a recording method thereof are disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-116058. A write-once medium using a dye material is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-297407.

  In the case of an inorganic member, the reflectivity of the recording mark portion formed by the irradiated laser beam has an H / L (High-to-Low) characteristic that is lower than the reflectivity before the laser beam irradiation. The organic member has L / H (Low-to-High) characteristics in which the reflectance of the recording mark portion is increased. In the above document, a recording waveform composed of a recording power and a bias power having a bias power in the space portion is shown.

  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 many papers on the PRML technology. For example, “High-density recording / playback 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 front and rear edges of the recording marks before and after the recording mark greatly affects the reproduction signal quality. This also means that the adjustment of the recording strategy is 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 instead of jitter that has been used in the conventional evaluation of the signal quality of the reproduced waveform. It has been found that the conventional jitter cannot be used as an evaluation index when the optical disk is made as dense as an HD DVD.

  PRSNR is a signal quality evaluation index instead of jitter, and is an SNR in PRML. PRSNR is an index adopted in HD DVD. Furthermore, the PRSNR can be converted into an error rate. 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. 43, No. 7B, 2004, pp. 4859-4862“ Signal-to-Noise Ratio in a PRML Detection BT DetectK ” al ".

  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. In HD DVD, the modulation code is also different from that of a conventional DVD. The modulation code of HD DVD is a modulation code called ETM (Eight to Twelve Modulation). The shortest mark 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 or shortest space length is 3T. Therefore, the recording strategy is different between the two. For example, in the case of a DVD-R, a recording mark 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 recording mark length is 2T, if recording is performed with k-2 pulses, there will be no output pulse at 2T. 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.

  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, as in the technique disclosed in the above-mentioned Japanese Patent Laid-Open No. 2000-182244, an optimum recording strategy is obtained with an adjustment method that is coarse and assumes that each parameter independently affects the signal quality. 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 14T space width and 14T mark width), as shown in the above-mentioned Japanese Patent Application Laid-Open No. 2000-30254. In this 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 that.

  The conventional recording strategy is not for PRML detection but for binary detection using a slicer, and cannot be used as it is in a system using PRML. Similarly, the conventional adjustment method of the recording strategy is an adjustment method that does not assume PRML detection, such as using conventional jitter. In a high-density optical disc such as HD DVD, since the signal index called jitter cannot be measured, the conventional adjustment method of the recording strategy cannot be applied.

  Further, conventionally, a modulation code having only a signal of 3T or more different from that of HD DVD has been assumed, so that the recording strategy is different from that of HD DVD or the like. In addition, since the material of the medium is different and the bias power affects the performance of the HD DVD additional recording medium, it is necessary to consider the adjustment. That is, the conventional technology cannot be applied as it is to an HD DVD or the like.

  Because of this situation, it is clear how to adjust the recording strategy and which recording strategy parameter should be adjusted in what order in a high density and PRML system such as HD DVD. This is a very big problem in developing a high-density optical disc.

  Japanese Patent Application Laid-Open No. 2001-143265 discloses a method of recording input data on an optical recording medium by a recording pulse composed of a first pulse, a last pulse, and a multi-pulse train. In this method, first, the waveform of the recording pulse is controlled according to the current mark size of the input data and the previous and / or subsequent space size, and an adaptive recording pulse is generated. Input data is recorded on the optical recording medium by the adaptive recording pulse. According to this method, the modulation pattern sequence is divided into short, medium, and long pulses as low grouping and high grouping, and adjustment is performed by a complicated combination.

  Japanese Patent Laid-Open No. 2006-302332 discloses a recording / reproducing apparatus that adjusts recording pulse parameters related to the shortest recording mark shape. The recording / reproducing apparatus includes a recording pulse adjusting unit that adjusts a recording pulse when recording information, and a trigger detecting unit that detects a trigger that performs the recording pulse adjusting unit. The recording pulse adjusting means adjusts the recording pulse parameter related to the shortest recording mark shape in response to the detection of the trigger. This recording / reproducing apparatus adjusts the recording pulse parameter according to the space length immediately before the mark.

  As described above, it is difficult to adjust the recording strategy as the density of the optical disk increases. Therefore, it is not clear in what order and by what method the recording strategy parameter should be adjusted.

  An 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 can adjust a recording strategy parameter at high speed.

  It is another object of the present invention to provide a method for adjusting a signal recording condition for an optical information recording medium and an information recording / reproducing apparatus with improved recording / reproducing performance.

  In an aspect of the present invention, a signal recording condition adjusting method for an optical information recording medium is a signal recording condition adjusting method in an optical recording method in which a pattern row is recorded by irradiating an information recording medium with intensity-modulated laser light. It is. The pattern row includes a mark, a space immediately before the mark, and a space immediately after the mark. The mark length indicates the irradiation time of the laser beam when recording the mark. The immediately preceding space length indicates the irradiation time of the laser beam when securing the immediately preceding space. The immediately following space length indicates the irradiation time of the laser beam when securing the immediately following space. The signal recording condition adjusting method includes a previous stage strategy setting step and a trailing edge adjusting step corresponding to the subsequent space length. In the previous strategy setting step, a recording strategy corresponding to the mark length is set without depending on the immediately preceding space length and the immediately following space length. In the trailing edge adjustment step corresponding to the subsequent space length, the trailing edge falling edge position of the recording strategy set in the preceding strategy setting step is adjusted based on the immediately following space length. This trailing edge adjustment step corresponding to the following space length is a uniform after changing the trailing edge falling edge position of the recording strategy corresponding to the mark having a mark length greater than or equal to a predetermined length by the same amount based on the immediately following space length. An edge adjustment step.

  In another aspect of the present invention, an information recording / reproducing apparatus includes an optical head, an LD driving unit, an RF circuit unit, and a recording strategy adjusting unit. The optical head irradiates an information recording medium with intensity-modulated laser light to record a pattern sequence. This pattern row includes a mark, a space immediately before the mark, and a space immediately after the mark. The LD drive unit drives the laser beam recording power and bias power by independently controlling them. The RF circuit unit measures and outputs the signal quality based on the reproduction signal reproduced from the information recording medium. The recording strategy adjustment unit adjusts the recording strategy by changing the recording parameter based on the signal quality. The recording strategy adjustment unit includes a previous stage strategy setting unit and a trailing edge adjustment unit corresponding to the subsequent space length. The immediately preceding space length indicates the irradiation time of the laser beam when securing the immediately preceding space, the immediately following space length indicates the irradiation time of the laser beam when recording the immediately following space, and the mark length indicates when the mark is secured Assuming that the irradiation time of the laser beam is shown, the previous-stage strategy setting unit sets the recording strategy corresponding to the mark length without depending on the immediately preceding space length and the immediately following space length. The trailing edge adjustment unit corresponding to the subsequent space length changes the trailing edge falling edge position of the recording strategy corresponding to the mark having a mark length longer than a predetermined length by the same amount based on the immediately following space length. adjust.

  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 1C are diagrams showing types of recording strategies (rectangular type). FIG. 1A is a diagram showing a simple rectangular recording strategy. FIG. 1B is a diagram showing a rectangular recording strategy in which the head is emphasized. FIG. 1C is a diagram showing a rectangular recording strategy in which the beginning and the end are emphasized. 2A to 2C are diagrams showing the types of recording strategies (pulse train type). FIG. 2A is a diagram showing a pulse train type (multi-pulse type) (basic type) recording strategy having binary power levels. FIG. 2B is a diagram showing a recording strategy in which the recording power of each pulse train type pulse is set to an independent ternary power level of a total of four values. FIG. 2C is a diagram showing a pulse train type recording strategy composed of ternary power levels. 3A to 3C are diagrams showing a recording strategy (pulse train type) in the present invention. FIG. 3A is a diagram illustrating an NRZI signal. FIG. 3B is an example of a pulse signal for recording. FIG. 3C is another example of a recording pulse signal. FIG. 4A is a diagram illustrating an example of a strategy parameter table. FIG. 4B is a diagram illustrating another example of the strategy parameter table. FIG. 4C is a diagram showing still another example of the strategy parameter table. FIG. 5 is a diagram showing a PRSNR measurement result. FIG. 6 is a diagram illustrating an example of adjusted parameters. FIG. 7 is a diagram showing the configuration of the information recording / reproducing apparatus according to the embodiment of the present invention. FIG. 8 is a diagram showing a configuration of the RF circuit unit according to the embodiment of the present invention. FIG. 9A is a diagram illustrating an NRZI signal. FIG. 9B is a diagram for explaining a (k−1) type pulse train recording strategy. FIG. 9C is a diagram for explaining a (k) type pulse train recording strategy. FIG. 10 is a diagram showing a recording condition adjusting method according to the first embodiment of the present invention. FIG. 11 is a diagram illustrating an example of adjusted parameters. FIG. 12 is a diagram showing a recording condition adjusting method according to the second embodiment of the present invention. FIG. 13 is a diagram illustrating an example of adjusted parameters. FIG. 14 is a diagram showing an example of parameters for each medium manufacturer according to the third embodiment of the present invention. FIG. 15A is a diagram illustrating an NRZI signal. FIG. 15B is a diagram for explaining the (k−1) type non-multi-recording strategy. FIG. 15C is a diagram for explaining the (k) type non-multi-recording strategy. FIG. 16 is a diagram showing a recording condition adjusting method according to the fourth embodiment of the present invention. FIG. 17A to FIG. 17C are diagrams showing measurement examples of each performance index when arbitrary parameters (for example, pulse width, power, etc.) are changed. FIG. 17A is a diagram illustrating a measurement example of the PRSNR value when the parameter is changed. FIG. 17B is a diagram illustrating a measurement example of the error rate when the parameter is changed. FIG. 17C is a diagram illustrating a measurement example of the number of PI error bytes when the parameter is changed.

  Embodiments of the present invention will be described with reference to the drawings. First, recording strategy parameters adjusted when recording on an information recording medium will be described.

  The recording power and the recording pulse width are parameters that affect each other. The parameter relating to the recording pulse width includes the output start timing and end timing of the pulse. Furthermore, as a parameter relating to the recording pulse width, the start or end edge position of the recording pulse that is changed according to the space length immediately before or after the recording pulse corresponding to the mark portion (the leading edge position or the leading edge position). Downstream edge position) is adjusted as a parameter. However, the number is large, and if the adjustment is performed rapidly, not only high-speed adjustment is possible, but also local optimization tends to occur, and good performance of the medium cannot be brought out. This is the reason why it has been difficult to adjust the recording strategy.

  Here, the definition of the recording strategy will be described with reference to FIGS. 3A to 3C. 3A to 3C show a pulse train type recording strategy. Based on an NRZI (non return to zero inverted) signal (FIG. 3A), a pulse signal for recording (FIGS. 3B and 3C) is generated. Light having a bias power is applied to the space portion. The recording pulse for the mark portion swings from the bottom power level to the recording power level. Each pulse has a pulse width defined by a time normalized by a unit time T. The rising edge position and the falling edge position of each pulse are defined by the time normalized by the unit time T from the reference position indicated by the upward arrow in the drawing.

  In the case of the recording strategy shown in FIG. 3B, the falling position of each pulse is set as a parameter with reference to the rising edge position of the middle pulse. The top pulse width is shown as a value increased or decreased with respect to the width of Tmp from the reference position. Further, since there is no last pulse in the 2T recording strategy, the trailing edge falling edge position is indicated by the normalized time from the reference position of the symbol “R” in the figure.

  In the case of the recording strategy shown in FIG. 3C, the rising edge position of each pulse is set as a parameter with reference to the falling edge position of the middle pulse. In both cases of FIGS. 3B and 3C, there is basically no change, but attention is required because the way the numerical values are displayed is different.

  Among the parameters that determine the size (length) of the mark portion, the conditions regarding the position of the trailing edge of the last end of the recording pulse are arranged. Depending on the length of the mark part (mark length), the trailing edge position of the last end is determined without depending on the length of the space part (space length) following the mark part (condition 1), and the mark Comparison is made with the case where the trailing edge position of the rearmost end is determined not depending on the mark length of the portion but depending on the space length of the space portion following the mark portion (condition 2). Here, the reason for focusing on the position of the rearmost edge is that the effect of heat accumulation due to thermal diffusion becomes more remarkable behind the formation mark.

  The conditions 1 and 2 will be described using an example of a strategy parameter table. When ETM modulation is used and the parameters corresponding to 4T or more marks and spaces are made common, the mark length and space length are 2T, 3T, 4 to 13T (however, except for 12T, 13T is a synchronization pattern). There are three combinations of the mark length and the space length immediately after the mark length, as shown in FIG. Therefore, nine values are set for the parameter indicating the trailing edge position at the end.

  If condition 1 is applied to this, as shown in FIG. 4B, three parameters a1, b1, and c1 are obtained. This indicates that the parameter corresponding to the 2T mark is the same set of parameter values a1 regardless of the space length of the subsequent space portion. It can be seen that by applying Condition 1, the number of parameters is compressed from 9 to 3, which makes it easier to handle. Furthermore, when Condition 2 is applied, three parameters a2, d2, and g2 are obtained as shown in FIG. 4C. Again, the number of parameter groups is compressed from 9 to 3.

  FIG. 5 shows the result of measuring the PRSNR for a plurality of currently available HD DVD-R media when the recording strategy is adjusted by applying the above conditions 1 and 2 and when the recording strategy is not applied. . An example of the parameters adjusted at that time is shown in FIG. The unit is one recording unit length (T). FIG. 6 shows parameters for condition 2 and non-application, and the numerical values are values based on the definition of the recording strategy shown in FIG. 3B.

  Here, the symbols used in the description will be described. In a symbol written as mXsY such as “m8s2”, a number “X” following “m” indicates a mark length, and a number “Y” following “s” indicates a space length. That is, mXsY represents that a mark portion having a mark length “X” T is followed by a space portion having a space length “Y” T. However, when X or Y is 4, it represents a length of 4T or more. M234 indicates a mark length of 2T or more. Therefore, m234s2 in the drawing indicates a case where a mark portion having a mark length of 2T or more is followed by a space portion having a space length of 2T, which indicates the parameter “a2” in FIG. 4C. m234s3 indicates the parameter “d2” in FIG. 4C, and m234s4 indicates the parameter “g2” in FIG. 4C. The numerical values shown in the figure corresponding to these indicate the length from the parameter reference position (time: unit is T).

  The top pulse width is displayed as a value increased or decreased with respect to the width of Tmp from the reference position. Further, when this recording strategy is applied, since there is no last pulse in the 2T recording strategy, the parameter indicating the trailing edge falling edge position is shown as an amount from the reference position indicated by the symbol “R” in FIG. 3B. It is. As shown in FIG. 3C, when the parameter reference position is changed, the notation values of the parameters are different.

  By the way, as shown in FIG. 5, it can be seen that the performance is improved when the condition 2 is applied as compared with the case where the condition 1 is applied. This is considered to be due to the following reason.

  As described above, heat accumulation due to thermal diffusion becomes more prominent behind the formation mark. Since the supply of heat for forming the mark portion is cut off at the last portion of the recorded mark portion by the space portion immediately after that, heat accumulation is alleviated. Therefore, in the space portion, heat conduction to the subsequent portion is also eased. Here, when adjustment is performed by paying attention only to the mark length of the mark portion to be recorded without considering the immediately following space length (condition 1), various thermal diffusions occur due to the difference in the immediately following space length. Non-linear distortion remains without being relaxed. For this reason, the effect is high for a certain mark length and space length combination, but the effect of the combination of another mark length and space length is low, and the correction effect is difficult to understand comprehensively. End up. Further, if the density is increased and the mark interval is narrowed, the non-linearity becomes more remarkable. A reproduced waveform with strong nonlinearity is not desirable because the performance of PRML detection is significantly deteriorated.

  On the other hand, paying attention to the space length immediately after the mark and considering that the degree of thermal diffusion differs depending on the space length, the same is achieved by adjusting the trailing edge of the mark immediately before the same space length. It is possible to eliminate distortion that occurs when each space length has a degree of diffusion capability. Even if distortion remains, it becomes the same kind of distortion depending on the space length, and a state where a number of distortions are combined can be relaxed, so that the uniformity is improved and the correction effect is enhanced. In addition, since the number of parameters to be adjusted is compressed, the efficiency of the adjustment is improved and the adjustment can be performed at high speed. Furthermore, since the effect itself becomes clear, adjustment with high accuracy can be performed.

  In addition, when many products are targeted, for example, in an information recording / reproducing apparatus, light beam quality and the like vary, and in a medium, a recording film formation state and the like vary. Furthermore, when parameters are individually adjusted including variations in which they are combined, the parameters are likely to have different values. While very well matched to beam quality and media conditions during adjustment, many other device and media combinations may not necessarily be the best parameters. On the other hand, in the present invention, since the parameters are gathered, the parameter values are not diversified, the applicability thereof is improved, and the correction effect can be widely applied.

  FIG. 7 shows the configuration of the information recording / reproducing apparatus according to the first embodiment of the present invention. The information recording / reproducing apparatus 1 includes a spindle drive system 2, an optical head unit 3, an RF circuit unit 4, a demodulator 5, a modulator 7, a servo controller 10, and a system controller 6. The spindle drive system 2 drives the optical disc 14. The optical head unit 3 includes a laser diode (LD) 8, a beam splitter 11, a light receiving unit 12, and an objective lens 15. The optical head unit 3 irradiates the optical disk 14 with light and detects the reflected light. That is, the light emitted from the laser diode (LD) 8 is collected by the objective lens 15 and irradiated onto the optical disk 14. The reflected light is separated from the emitted light by the beam splitter 11, detected by the light receiving unit 12, converted into an electric signal, and output to the RF circuit unit 4. In the present embodiment, a measurement result by the optical head 3 having an LD wavelength of 405 nm and NA (numerical aperture) of 0.65 is exemplified.

  The RF circuit unit 4 performs processing such as filtering and equalizing on the input signal. In the present embodiment, the RF circuit unit 4 calculates the PRSNR, amplitude, or modulation degree. The demodulator 5 demodulates the output signal of the RF circuit unit 4 and outputs it to the system controller 6. The modulator 7 modulates a signal to be recorded. The LD driver 9 drives the laser diode 8 based on the output signal of the modulator 7. The servo controller 10 controls the servo signal. The system controller 6 controls the entire apparatus. The system controller 6 includes a recording strategy adjuster 13 that controls adjustment of the recording strategy, recording power, and bias power.

  FIG. 8 shows a configuration of the RF circuit unit 4 according to the present embodiment. The RF circuit unit 4 performs analog signal processing by a prefilter and an auto gain control (AGC) circuit (not shown), and converts the digital signal by an A / D converter (ADC) 21. From the digitally converted signal, a clock is extracted by a phase-locked loop (PLL) circuit 22 and the sampling frequency of the A / D converter 21 is controlled. The offset is corrected by the offset corrector 23, and the asymmetry is corrected by the asymmetry corrector 24. Further, it is converted into a binary signal by a maximum likelihood detector 25 having an adaptive equalizer and a Viterbi decoder for PR (1, 2, 2, 2, 1). An error calculator 26 that receives this binarized signal and the output signal of the asymmetry corrector 24 calculates the difference and supplies it to the offset corrector 23.

  In the maximum likelihood detector 25, the signal after adaptive equalization and the data string signal after Viterbi decoding are input to the signal comparator, and the PRSNR is calculated by the signal comparator. Noise at each time required for the PRSNR calculation includes an ideal signal waveform obtained by convolution integration of a data string signal after Viterbi decoding and a (1, 2, 2, 2, 1) vector, and an adaptive equalized signal (actual signal). (Waveform) difference.

  On the other hand, the recording strategy adjuster 13 performs recording based on the number of error bytes in a predetermined ECC (Error Correction Code) block obtained from the data sequence demodulated by the demodulator 5 and the PRSNR sent from the RF circuit unit 4. Recognize the correspondence between conditions and signal quality, and control the series of adjustment sequences to adjust the optimum recording strategy. In this embodiment, as the recording strategy, the (k-1) type shown in FIG. 9B is applied among the pulse train type recording strategies shown in FIGS. 9A to 9C.

  In the embodiment described below, the optical disk 14 is an information recording medium corresponding to the HD DVD standard, and a write-once information recording medium (for example, HD DVD-R) that can be recorded only once is exemplified. . The physical format of the optical disk 14 is an in-groove format with a bit pitch of 0.15 μm and a track pitch of 0.40 μm.

  An optical disc 14 such as an HD DVD-R is a type of medium in which an organic dye-based material corresponding to a short wavelength is used for a recording layer, and the reflectance becomes high when recording is performed, and is called Low-to-High media. Yes. The optical disk 14 has a guide groove called a pregroove formed on a disk-shaped transparent substrate made of polycarbonate and having a thickness of 0.6 mm and a diameter of 12 cm. At the time of recording and reproducing information, the light beam of the information recording / reproducing apparatus 1 (optical disk drive) can be scanned along the guide groove. A recording film is formed on the substrate.

  Next, the recording condition adjusting operation of the information recording / reproducing apparatus 1 will be described. As shown in FIG. 10, the adjustment of the recording strategy is performed in two stages, that is, the previous stage strategy setting (step S10) and the trailing edge adjustment corresponding to the subsequent space length (step S20).

(Step S10)
In the previous-stage strategy setting, a (k-1) type pulse train type recording strategy shown in FIG. 9B is applied as a basic strategy. The pulse width is changed by moving the pulse trailing edge of each pulse with reference to the parameter reference position shown in FIG. 3B.

  In the previous stage strategy setting, first, the base strategy is determined (step S12). In determining the base strategy, the pulse widths of the top pulse, middle pulse, and last pulse are all set to the same pulse width from the reference position, and the pulse width is changed in the same direction. For example, the pulse width is changed from 0.38T to 0.86T in approximately 0.03T increments. In each pulse width, an adjustment pattern is recorded on the information recording medium and reproduced from the recorded area. The PRSNR indicating the recording quality at that time is measured, and the pulse width when recording is best performed is set as the basic pulse width. Based on this basic pulse width, a base strategy is determined.

  Since the upper limit of the recordable recording power of the information recording / reproducing apparatus 1 is 12 mW, the recording margin is set to 9.0 mW and the bias power is set to 3.6 mW in consideration of the power margin, changes with time, environmental changes, and the like. . The bottom power is assumed to be 0.1 mW, which is the lowest power that can be set in the apparatus at the time of recording, and this power level is not particularly adjusted. Further, in the strategy adjustment, only when this base strategy is determined, the asymmetry correction circuit 24 is operated to perform PRML detection, and the PRSNR is measured.

  Next, the top pulse width corresponding to the shortest mark is determined based on the basic pulse width obtained in step S12 (step S14). The recording quality index is similarly PRSNR. The pulse width at this time is set to a range of approximately −0.06T to + 0.18T with the basic pulse width as the center. That is, the top pulse width is changed within the range from (basic pulse width−0.06T) to (basic pulse width + 0.18T) in steps of approximately 0.03T, and recording / reproduction is performed.

  Next, the recording power is determined (step S16). The recording power includes recording power and bias power, and is adjusted in 5% increments within a range of approximately ± 20% around a predetermined power value. The evaluation index is PRSNR, and the recording power and bias power at which the PRSNR is the best value in each adjustment range are obtained. The above is the previous stage strategy setting process (step S10). In this process, adjustment is performed without particularly distinguishing the space length before and after the mark. By adjusting so far, the best value of PRSNR is 28.

(Step S20)
Subsequently, trailing edge adjustment corresponding to the subsequent space length is performed (step S20). Here, based on the parameters determined in the previous strategy setting (step S10), recording / reproduction is performed by changing the end edge position of the recording strategy for the case where the immediately following space length is 2T, 3T, or 4T or more. Is performed, and the parameter that provides the best recording quality is determined. The mark length of the mark to be recorded is 2T, 3T, 4T or more, and the end edge position is adjusted based on the basic pulse width obtained in the previous stage strategy setting process (step S10). The pulse width is set to a range of (basic pulse width−0.24T) to (basic pulse width + 0.12T) in steps of approximately 0.06T. Note that the pulse width of each pulse is changed by the same amount in the same direction.

  That is, uniform trailing edge adjustment is performed in which the trailing edge falling edge position of the previous-stage recording strategy with respect to the 2T mark or more mark as the specific mark is changed by the same amount according to the space length immediately after the mark. As the order of adjustment, the space length immediately after is 2T, the case of 3T, the order of 4T or more, and the result obtained by the previous adjustment is used for each adjustment.

  When the above adjustment is performed, the PRSNR becomes 32, and it can be seen that the performance is further improved as compared with the previous stage strategy setting. FIG. 11 shows the result of the adjustment parameter determined in the previous-stage strategy setting and the result of the adjustment parameter when performing the trailing edge adjustment corresponding to the subsequent space length (step S20). The unit is T.

  As described above, according to the recording condition adjusting method and the information recording / reproducing apparatus of the present invention, it can be seen that good recording conditions can be obtained at high speed even in HD DVD using PRML detection. In the trailing edge adjustment corresponding to the subsequent space length, the order of adjustment of the rearmost edge of the mark having the same space length immediately after is not limited to the order in the present embodiment, and can be replaced. The adjusted parameters are carried over at the next another parameter adjustment.

  Further, if the forefront edge position is adjusted for each mark length immediately before or after the recording power determination (step S16), the performance may be further improved. Specifically, the width of the top pulse for mark recording longer than the shortest mark is set by changing the width of the top pulse for recording a mark having a length longer than the shortest mark by one recording unit length (1T). Is done. That is, a second top pulse width setting step is provided. In the case of ETM modulation, the shortest mark length is 2T (the longest is 13T), and a mark of 3T or more corresponds to this. Adjustment is performed by dividing the category into the mark length 3T and the mark length 4T or more. All mark lengths greater than 4T have the same top pulse width.

  Adjustment is performed in the order of the mark length 3T and the mark length 4T or more. Based on the basic pulse width obtained in the base strategy determination (step S12), the top pulse width is sequentially increased in the order of the top pulse width corresponding to the mark having the mark length of 3T and the top pulse width corresponding to the mark having the mark length of 4T or more. It is determined. The pulse width at this time is changed in a range of (basic pulse width−0.06T) to (basic pulse width + 0.18T) in units of approximately 0.03T. The leading edge of each top pulse is changed, PRSNR is calculated as an index by recording / reproducing, and the top pulse width is determined. The degree to which the top pulse width is adjusted is determined in consideration of the time required for the adjustment, the limitation of the adjustment region, and the adjustment accuracy.

  With reference to FIG. 12, the recording adjustment method of the information recording / reproducing apparatus according to the second embodiment of the present invention will be described. The information recording / reproducing apparatus 1 is described in the first embodiment, but the operation of the recording strategy adjuster 13 is different. The information recording medium is an HD DVD-R, as in the first embodiment. In the adjustment method shown in FIG. 12, the previous-stage strategy setting (step S10) and the trailing edge adjustment corresponding to the subsequent space length (step S20) are described in the first embodiment, and thus detailed description thereof is omitted here. Then, the subsequent trailing edge adjustment corresponding to the shortest mark (step S30) will be described as being performed up to the trailing edge adjustment corresponding to the subsequent space length.

  In the shortest mark corresponding rear edge adjustment (step S30), the position of the rearmost edge of the shortest mark when the shortest mark and the shortest space are combined is adjusted. That is, immediately after the mark having the mark length of 2T, the parameter a indicating the end edge position of the 2T mark when the space having the space length of 2T is secured (m2s2) is set (FIGS. 4A to 4C). reference). The parameter of the end edge is adjusted in increments of 0.03T from the position of approximately −0.06T to the position + 0.12T of the value set in the trailing edge adjustment corresponding to the subsequent space length (step S20). The PRSNR is calculated by recording / reproducing while changing the position of the end edge. The value indicating the position of the rearmost edge when the best PRSNR is obtained is the value of the parameter to be obtained. Actually, as shown in FIG. 13, the value at m2s2 was 0.72. At this time, the PRSNR was 34, confirming that the performance could be further improved.

  This is because the shortest mark is the smallest mark, and its formation is particularly susceptible to heat, and the SNR (signal to noise ratio) is also severe. Therefore, especially when the 2T mark is adjusted individually, it is considered that the performance is improved. Depending on the medium, the performance can be further improved by adjusting the trailing edge (m2s3) of the 2T mark when the space length immediately after is 3T and adjusting the trailing edge (m2s4) of the 2T mark when the space length is 4T or more. May be. Also in this case, since the trailing edge adjustment parameter corresponding to the trailing space length is used, the adjustment can be performed at a higher speed than in the case where the parameter is applied indiscriminately.

  As described above, according to the recording condition adjusting method and information recording / reproducing apparatus of the present invention, good recording conditions can be obtained at high speed even in HD DVD using PRML detection. It should be noted that how much this adjustment is performed is determined in consideration of the time required for the adjustment, the limitation of the adjustment region, and the adjustment accuracy.

  Next, a third embodiment of the present invention will be described. In this case, a manufacturer name is recorded on the information recording medium, or basic parameter values are recorded as shown in FIG. When only the manufacturer name is recorded, as shown in FIG. 14, the information recording / reproducing apparatus 1 may hold basic parameter values corresponding to the manufacturer name. The information recording / reproducing apparatus 1 sets the base (basic) strategy based on the basic parameter values in the base strategy determination (step S12) of the previous stage strategy setting (step S10). Accordingly, test recording / reproduction is not performed in the base strategy determination (step S12), and this point is different from the first and second embodiments described above.

  An optical disc 14 having Disc Manufacturing information including information such as a disc manufacturer name and a production location is loaded into the information recording / reproducing apparatus 1. The optical head 3 is moved to the system information area of the optical disc 14, and the information recording / reproducing apparatus 1 acquires the disc type, the disc manufacturer name, and the like therefrom. The information recording / reproducing apparatus 1 determines that the loaded optical disk is, for example, the medium A. Subsequently, as shown in FIG. 14, the information on the top pulse width and the last pulse width of 2T, 3T, 4T or more corresponding to the multi-pulse (middle pulse) width Tmp = 0.78T, in advance by another test apparatus. The performance obtained by combining the performance (assumed PRSNR), the recording power setting value including the recording power / bias power not shown in FIG. 14 and the like are acquired. Here, the type of the recording strategy is assumed to be a (k-1) type pulse train shown in FIG. 9B.

  Next, as shown in FIG. 10, the recording conditions are adjusted. In the previous stage strategy setting (step S10), the recording parameters relating to the medium A acquired previously are set as the base strategy (step S12), and the top pulse width is set (step S14). That is, the information on the multi-pulse (middle pulse) width, 2T, 3T, 4T or more top pulse width and last pulse width acquired by determining the medium A includes the start and end timings of the base (basic) strategy. Set as

  Next, the recording power is determined (step S16). Here, the power value previously held as information by the information recording / reproducing apparatus 1 is used, and the recording power is set to 9.0 mW and the bias power is set to 3.6 mW as the predetermined power values. The information recording / reproducing apparatus 1 may use the average power of many HD DVD-R Low-to-High media stored in advance. The bias power is fixed, and the recording power is changed to ± 20% with respect to 9.0 mW within 5% increments, and recording / reproduction is performed. At this time, the recording power that could be recorded best was 9.4 mW. Note that the setting of the pulse width at this time is a parameter that does not depend on the space length immediately before or after the mark.

  Subsequently, the trailing edge adjustment corresponding to the subsequent space length (step S20) is executed. In the trailing edge adjustment corresponding to the succeeding space length, the mark length is 2T, 3T, 4T when the immediately following space length is 2T, 3T, 4T or more based on the parameter value set in the previous stage strategy setting (step S10). The end edge position of the recording strategy corresponding to each of the above marks is determined. The rearmost edge position is set to a position where the basic pulse width set in the previous stage strategy setting is changed within a predetermined range and the evaluation index PRSNR is the best. Here, the predetermined range is a range from (basic pulse width−0.24T) to (basic pulse width + 0.12T), and is changed in increments of 0.06T. The pulse width is changed in the same direction by the same amount. As the order of adjustment, the space length immediately after is 2T, the case of 3T, the order of 4T or more, and the result obtained by the previous adjustment is used for each adjustment.

  As described above, when the adjustment is performed, the PRSNR becomes 22, and as shown in FIG. 14, a value equivalent to the assumed PRSNR obtained by adjusting the performance of the medium manufacturer in advance by the medium A was obtained.

  In this way, the manufacturer name of the medium can be identified by the ID of the medium, and this information can be associated in advance with a predetermined recording strategy including the recording condition parameter in the information recording / reproducing apparatus. When recording strategy parameter information is held on the medium, by reading and using the information, a predetermined recording strategy can be obtained faster and adjustment can be performed at higher speed.

  As described above, according to the recording condition adjusting method and the information recording / reproducing apparatus of the present invention, it can be seen that good recording conditions can be obtained at high speed even in HD DVD using PRML detection.

  Compared with the first embodiment, the method described in the present embodiment is easy to use for a medium in which parameters are set in advance. The first embodiment is effective in that the recording strategy can be adjusted even if a medium that does not exist at the time of drive shipment is loaded in the information recording / reproducing apparatus, and the accuracy can be widely used. The method described in the present embodiment is advantageous in the case of simply adjusting only a medium that currently exists.

  Next, a fourth embodiment of the present invention will be described. The adjustment method described here is applicable not only to a multi-pulse type recording strategy but also to a non-multi-type (rectangular base) recording strategy as shown in FIGS. 15A to 15C. In that case, it is not the multi-pulse that determines the skeleton, but the middle power Pm shown as P3 in FIGS. 15A to 15C. Therefore, equivalent adjustment is possible if the middle power Pm is similarly controlled instead of the multi-pulse.

  15A to 15C show non-multi waveforms described in the present embodiment. This non-multi waveform has a constant pulse train portion of the multi-pulse waveform. The role played by the multi-pulse part is replaced by the middle power Pm. In the following description, the (k-1) type non-multi type is used (FIG. 15B). Here, the (k-1) type is synonymous with the example in the pulse train and indicates that the length is "N-1" with respect to the NRZI signal (the length is N). For example, the time width is 7T for 8T and 2T for 3T. In the k-type, the basic rule is a time width of 8T for 8T and 3T for 3T.

  The information recording / reproducing apparatus 1 shown in FIG. 7 uses the same type of HD DVD-R medium as described in the first embodiment. In this adjustment method, as shown in FIG. 16, the previous stage strategy setting (step S10) and the trailing edge adjustment corresponding to the subsequent space length (step S20) are performed. In the previous stage strategy setting (step S10), the top pulse and the last pulse are adjusted by changing the positions of the respective leading edges. Therefore, in the previous stage strategy setting (step S10), as shown in FIG. 16, base strategy determination (step S40), shortest mark top pulse width determination (step S42), recording power determination (step S44), shortest mark Other adjustments are made in the order of determining the top pulse width (step S46) and determining the last pulse width (step S48). In this example, in the previous stage strategy setting (step S10), the top pulse is adjusted by changing the leading edge of the pulse, and the last pulse is adjusted by changing the leading edge of the pulse.

  In the base strategy determination (step S40), the middle power P3 is determined. Since the upper limit of the recordable recording power of the information recording / reproducing apparatus 1 is 12 mW, the average power margin of many media, changes with time, environmental changes, and the like are taken into consideration, and the recording power P1 is 9.0 mW, and the bias power P2 is set to 3.6 mW. For the top pulse width and last pulse width, a basic pulse width of 0.59T is set as an average value of parameters obtained in many media. Since the middle power P3 has a recording power P1 of 9.0 mW, the range of ± 20% is changed in steps of 5% around 4.5 mW, which is about half of the recording power P1. The middle power P3 when the best evaluation index is recorded / reproduced by the middle power P3 is selected, and the base strategy is determined. In the strategy adjustment, asymmetry correction is performed, PRML detection is performed, and the PRSNR is measured only when the base strategy is determined. As a result of obtaining the middle power P3 in this way, the middle power P3 = 5.2 mW was obtained.

  In the shortest mark top pulse width determination (step S42), the top pulse width in the shortest mark is determined. At this time, the recording power P1 is set to 9.0 mW, and the middle power P3 is set to 5.2 mW obtained in the base strategy determination (step S40). The basic pulse width is set to 0.59T. Under this condition, the top pulse width corresponding to the shortest mark is obtained using PRSNR as an index. That is, for the top pulse width, the range from (basic pulse width−0.06T) to (basic pulse width + 0.18T) is changed in increments of approximately 0.03T, and the PRSNR at each top pulse width is measured. The top pulse width when the best PRSNR is obtained is determined as the shortest mark top pulse width.

  Next, in the recording power determination (step S44), the recording power P1 and the bias power P2 are adjusted. The ratio between the recording power P1 and the middle power P3 is kept constant with the optimum value of the middle power P3 of 5.2 mW when the recording power P1 obtained in the base strategy determination (step S40) is 9.0 mW as a reference. . The recording power P1 is set in 5% increments within a range of approximately ± 20% around 9.0 mW. Accordingly, the middle power P3 is also changed to make the ratio constant. Recording / reproduction is performed for each set of recording power P1 and middle power P3, and PRSNR as a performance index is measured. The set of recording power P1 and middle power P3 that provides the best PRSNR is selected. Further, the bias power P2 is set within a range of approximately ± 20% centering on a predetermined power value in increments of 5%, and recording / reproduction is performed to measure PRSNR as a performance index. The bias power P2 that provides the best PRSNR is selected. Thus, the recording power P1, the bias power P2, and the middle power P3 are determined.

  Subsequently, the top pulse width other than the shortest mark is determined (step S46). That is, in step S46, the adjustment of the mark length 3T or 4T or more is performed. Therefore, according to the adjustment order in step S42 and step S46, the mark lengths are categorized into 2T, 3T, 4T or more, and are adjusted in this order. Parameters determined in the top pulse width adjustment for each mark length are applied to subsequent adjustments, and the parameters are sequentially determined. Further, the top pulse widths of marks with a mark length of 4T or more are all set to the same pulse width. Based on the basic pulse width obtained in the base strategy determination (step S40), the top pulse width corresponding to the mark having the mark length of 2T, the top pulse width corresponding to the mark having the mark length of 3T, and the mark having the mark length of 4T or more The top pulse width is sequentially determined in order of the corresponding top pulse width. The pulse width at this time is set by moving the leading edge position of the pulse in the range of (basic pulse width−0.06T) to (basic pulse width + 0.18T) in steps of approximately 0.03T. Recording / reproduction is performed at each pulse width, the PRSNR as a performance index is measured, and the pulse width when the best PRSNR is obtained is selected. In this way, the pulse width is determined for each category.

  Next, the last pulse width is determined (step S48). Regarding this last pulse, the 2T constituent pulses are expressed differently in the k-1 type and the k type, but in the k-1 type, the top pulse is adjusted using an edge different from the adjustment edge used in the previous step. That is, the adjustment at the trailing edge is performed, and the adjustment using the leading edge of the last pulse is performed in the k type. The adjustment here is performed in the order of the mark length 2T, 3T, 4T or more regardless of the space length before and after. The parameters determined in the last pulse width adjustment for each mark length are applied to subsequent adjustments, and the parameters are sequentially determined. Therefore, the adjustment is performed by categorizing the mark lengths 2T and 3T and the mark length 4T or more, and the last pulse widths in the marks having the mark length 4T or more are all set to the same pulse width. Based on the basic pulse width obtained in the base strategy determination (step S40), the last pulse width is sequentially determined in the order of the last pulse width corresponding to the 2T mark and the 3T mark, and the last pulse width corresponding to the mark of 4T or more. The The pulse width at this time is set by moving the trailing edge position of the pulse in steps of approximately 0.03T in the range from (basic pulse width−0.15T) to (basic pulse width + 0.18T). As in the case of determining the top pulse width (step S46), the last pulse width is determined for each category.

  As described above, the previous stage strategy setting (step S10) is performed. As the performance when the adjustment was attempted in this way, a PRSNR of about 22 was obtained.

  Next, the trailing edge adjustment corresponding to the subsequent space length (step S20) is performed. That is, based on the parameters set in the previous stage strategy setting (step S10), the last of the recording strategy corresponding to the marks having the mark lengths 2T, 3T, and 4T when the immediately following space length is 2T, 3T, and 4T or more. The edge edge position is adjusted. The end edge position is substantially 0 in a range from (basic pulse width−0.24T) to (basic pulse width + 0.12T) based on the basic pulse width set in the previous stage strategy setting (step S10). Changed in the same direction in increments of .06T. For each set end edge position, an adjustment pattern is recorded on the medium, reproduced from the recorded area, and PRSNR as an evaluation index is measured. The parameters are determined so that the PRSNR is the best. The adjustment is performed in the order in which the immediately following space length is 2T, 3T, 4T or more. For each adjustment, the result obtained in the previous adjustment is applied. In the trial result adjusted in this way, the PRSNR was 26.

  As a result of the above adjustment, the performance under the final recording conditions was about 26 in PRSNR. Thus, even in the case of the (k-1) type non-multi type, PRML detection can be performed by using the recording condition adjusting method and the information recording / reproducing apparatus for adjusting the end edge position of the mark corresponding to the same space length. Good recording conditions can also be obtained at high speed in the HD DVD used.

  In the present invention, as shown in FIG. 3C, it is possible to change the parameter reference position and perform the previous stage strategy determination (step S10). In that case, the base strategy adjustment (pulse width adjustment) in the recording strategy can obtain the same effect even if the pulse width is changed by changing the pulse width before the parameter reference position. Although the parameter value itself may be different from the reference position shown in FIG. 3B, it is not an essential problem.

  The present invention is not limited to a wavelength of 405 nm and NA of 0.65, and can be applied to any wavelength and NA. In the above embodiment, the numerical values when the class PR (12221) is used are exemplified, but other classes such as PR (1221) can be used in the same manner. Further, the modulation code has been described on the assumption that the ETM adopted in HD DVD is used, but other modulation codes can be used similarly. In that case, for example, the shortest data length such as kT (k is a natural number of 3 or more) may change. Furthermore, although adjustment in HD DVD has been exemplified, a Blu-ray disc (BD disc) may be used.

  Moreover, although PRSNR was illustrated as a performance parameter | index, you may adjust with an error rate (PRSNR can also be converted into an error rate). Further, as an index used in a sense that is qualitatively approximately equal to the error rate, the total number of rows in which an error is detected due to the number of error bytes generated in a predetermined number of ECC blocks or the parity on the inner side of the ECC A PI error may be used. FIG. 17A to FIG. 17C are diagrams showing measurement examples of each performance index when arbitrary parameters (for example, pulse width, power, etc.) are changed. FIG. 17A is a diagram illustrating a measurement example of the PRSNR value when the parameter is changed. FIG. 17B is a diagram illustrating a measurement example of the error rate when the parameter is changed. FIG. 17C is a diagram illustrating a measurement example of the number of PI error bytes when the parameter is changed.

  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. In addition, according to the present invention, it is possible to provide a method for adjusting a signal recording condition for an optical information recording medium and an information recording / reproducing apparatus with improved recording / reproducing performance.

  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.

Claims (15)

A method for adjusting signal recording conditions in an optical recording method in which a pattern row is recorded by irradiating an information recording medium with intensity-modulated laser light,
The pattern sequence is
Mark and
A space immediately before the mark,
Comprising a space immediately after the mark,
When recording the mark independently of the immediately preceding space length indicating the irradiation time of the laser light when securing the immediately preceding space and the immediately following space length indicating the irradiation time of the laser light when securing the immediately following space A previous-stage strategy setting step for setting a recording strategy corresponding to a mark length indicating the irradiation time of the laser beam;
A trailing edge adjustment step corresponding to a subsequent space length that adjusts the trailing edge falling edge position of the recording strategy set in the previous stage strategy setting step based on the immediately following space length; and
The trailing edge adjustment step corresponding to the subsequent space length includes:
A uniform trailing edge adjusting step of uniformly changing a trailing edge falling edge position of the recording strategy corresponding to the mark having the mark length equal to or longer than a predetermined length by the same amount based on the immediately following space length. Method for adjusting signal recording conditions on an optical information recording medium. The method for adjusting a signal recording condition on an optical information recording medium according to claim 1, wherein the predetermined length is the mark length of the shortest mark in the mark included in the pattern row. The predetermined length is one recording unit (1T) longer than the mark length of the shortest mark in the marks included in the pattern row,
The trailing edge adjustment step corresponding to the subsequent space length includes:
Independently of the recording strategy of the mark having the mark length equal to or longer than the predetermined length, the trailing edge falling edge position of the recording strategy corresponding to the shortest mark is the space length immediately after the space immediately after the shortest mark. The method for adjusting a signal recording condition to an optical information recording medium according to claim 1, further comprising a trailing edge adjusting step corresponding to a shortest mark that is adjusted based on the adjustment. The previous-stage strategy setting step includes:
The basic strategy setting step of adjusting the leading edge rising edge position, the trailing edge falling edge position, or both edge positions of the recording strategy corresponding to each of the mark lengths. A method for adjusting signal recording conditions on an optical information recording medium according to any one of the above. The previous-stage strategy setting step includes:
4. The optical recording medium according to claim 1, further comprising a step of setting the recording strategy based on setting information corresponding to each of the mark lengths recorded as control information on the information recording medium. 5. A method for adjusting signal recording conditions on an information recording medium. The previous-stage strategy setting step includes:
The optical information recording medium according to any one of claims 1 to 3, further comprising a step of setting the recording strategy based on setting information stored in advance in association with an identifier for identifying the information recording medium. Signal recording condition adjustment method. The trailing edge adjustment step corresponding to the subsequent space length includes:
A test recording step of recording the pattern row by stepwise changing the trailing edge falling edge position within a predetermined range at a predetermined interval;
A reproduction quality measuring step of reproducing the pattern sequence recorded in the test recording step and measuring a reproduction signal quality;
7. The step of setting the trailing edge falling edge position used for recording the pattern string indicating the best reproduction signal quality in the measured reproduction signal quality is provided. A method for adjusting signal recording conditions on the optical information recording medium described in the above. The method for adjusting a signal recording condition to an optical information recording medium according to claim 7, wherein the reproduction signal quality is one of a PRSNR value and an error rate calculated based on a reproduction signal obtained by reproducing the pattern string. An optical head that irradiates an information recording medium with intensity-modulated laser light to record a pattern sequence;
An LD driving unit for controlling and driving the recording power and bias power of the laser beam independently;
An RF circuit unit that measures and outputs signal quality based on a reproduction signal reproduced from the information recording medium;
A recording strategy adjustment unit that adjusts a recording strategy by changing a recording parameter based on the signal quality,
The pattern sequence is
Mark and
A space immediately before the mark,
Comprising a space immediately after the mark,
The recording strategy adjustment unit
The mark is not dependent on the immediately preceding space length indicating the irradiation time of the laser light when securing the immediately preceding space, and the immediately following space length indicating the irradiation time of the laser light when securing the immediately following space. A pre-stage strategy setting unit for setting a recording strategy corresponding to a mark length indicating an irradiation time of the laser beam when recording;
Corresponding to the subsequent space length by adjusting the trailing edge falling edge position of the recording strategy corresponding to the mark having the mark length equal to or longer than a predetermined length by changing the same amount by the same amount based on the immediately following space length. An information recording / reproducing apparatus comprising a trailing edge adjusting unit. The information recording / reproducing apparatus according to claim 9, wherein the predetermined length is the mark length of the shortest mark in the marks included in the pattern row. The predetermined length is one recording unit (1T) longer than the mark length of the shortest mark in the marks included in the pattern row,
The trailing edge adjustment unit corresponding to the subsequent space length further includes a trailing edge trailing edge of the recording strategy corresponding to the shortest mark independently of the recording strategy of the mark having the mark length equal to or longer than the predetermined length. The information recording / reproducing apparatus according to claim 10, wherein the edge position is adjusted based on a space length immediately after the space immediately after the shortest mark. The preceding stage strategy setting unit adjusts the leading edge rising edge position, the trailing edge falling edge position, or both edge positions of the recording strategy corresponding to each of the mark lengths. 11. The information recording / reproducing apparatus according to any one of 11 above. Setting information corresponding to each of the mark lengths recorded as control information on the information recording medium is read by the optical head,
The information recording / reproducing apparatus according to claim 9, wherein the previous-stage strategy setting unit sets the recording strategy based on the setting information. Holding setting information in association with an identifier for identifying the information recording medium in advance;
The information recording / reproducing apparatus according to claim 9, wherein the previous-stage strategy setting unit sets the recording strategy based on the setting information. The information recording / reproducing apparatus according to any one of claims 9 to 14, wherein the signal quality is one of a PRSNR value and an error rate calculated based on a reproduction signal obtained by reproducing the pattern string.

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