JP2008112509A - Optical disc recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the measurement of a reproduction jitter of a reproduction signal in case of the occurrence of intersymbol interference in the reproduction signal and to optimally set a recording laser pulse with the reproduction jitter as an index. <P>SOLUTION: The amplification value data of the reproduction signal at a prescribed sampling timing is acquired in an A/D conversion section 8. Viterbi decoding is performed relating to the amplification value data of the reproduction signal in a maximum likelihood decoding section 10. The binary data of the reproduction signal is decoded to form the amplification value data of the equalization signals having ideal PR (1, 2, 2, 2, and 1) characteristics in a partial response equalization section 13. A prescribed pattern is detected in a pattern detector 14. A reproduction jitter calculation section 1501 calculates the reproduction jitter from the expected value error of the amplification value data of the reproduction signal of the edge with respect to the amplification value data of the equalization signals of the edge of the mark included in the prescribed pattern. A laser pulse controller 1502 sets the waveform of the recording laser pulse based on the reproduction jitter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that records and reproduces information on a disc using a laser beam.

  2. Description of the Related Art Conventionally, in an optical disk apparatus that performs recording and reproduction of a rewritable optical disk, such as a DVD-R (Digital Versatile Disk Recordable), a predetermined area (PCA: Power) of the optical disk is formed in order to form a mark suitable for the characteristics of optical media. Test writing is performed while changing the emission waveform rule (hereinafter referred to as strategy) of a recording laser pulse composed of one or more pulse trains with respect to the calibration area), and a strategy with the optimum quality of the reproduction signal in the area is obtained.

For example, in Patent Document 1, an optimum strategy is obtained by referring to reproduction jitter of a reproduction signal as an index for evaluating the quality of the reproduction signal.
JP 2000-182244 A

  In recent years, high density and high speed recording of optical discs have been achieved, and PRML (proactive use of intersymbol interference caused by adjacent marks in recording and reproduction of high density optical discs such as HD-DVD and Blu-ray) Partial Response and Maximum Likelihood) is used. When recording and reproducing information using PRML, there is intersymbol interference in the reproduced signal, and it is difficult to detect the edge of the mark with the conventional method of simply comparing the reproduced signal with a specific threshold value. Therefore, it is not easy to observe the fluctuation of the mark edge and measure the reproduction jitter of the reproduction signal, and it is difficult to use the reproduction jitter of the reproduction signal as an index when setting the recording laser pulse optimally. .

  The present invention has been made in view of such circumstances, and the recording laser pulse can be optimized even when intersymbol interference occurs in the reproduction signal as in a high-density optical disc such as HD-DVD. An object of the present invention is to provide a simple optical disc apparatus.

  The present invention relates to a reproduction amplitude value data acquisition means for acquiring amplitude value data of a reproduction signal at a predetermined sampling timing, and maximum likelihood decoding of the amplitude value data in an optical disk apparatus for recording and reproducing information on a disk using laser light. And a maximum likelihood decoding means for decoding binary data and equalized amplitude value data for generating an equalized signal by performing partial response equalization on the binary data and outputting amplitude value data of the equalized signal An output means; a pattern detection means for detecting a predetermined pattern; and a laser pulse for setting a waveform of a recording laser pulse composed of one or more pulse trains based on equalization amplitude value data and reproduction amplitude value data of the predetermined pattern The gist is to provide setting means.

  Further, the apparatus further includes reproduction jitter calculating means for calculating reproduction jitter of the edge of the mark included in the predetermined pattern, the reproduction jitter calculating means including edge equalization amplitude value data and edge of the mark included in the predetermined pattern Calculating an expected value error (E) of the mark edge reproduction amplitude value data with respect to the mark edge equalization amplitude value data from the reproduction amplitude value data, and calculating the reproduction jitter based on the expected value error; desirable.

  Further, when the laser pulse setting means determines that the trailing edge is deviated from a predetermined position due to an expected value error (RE) of the trailing edge of the mark, the reproducing jitter (RJ) of the trailing edge is determined. It is desirable to adjust and set the trailing edge pulse waveform of the laser pulse.

  The information is divided into a plurality of pattern groups each having a mark length nT (n is an integer of 1 or more) and a space length mT (m is an integer of 1 or more). It is desirable to calculate the reproduction jitter every time.

  The laser pulse setting means preferably sets the waveform of the laser pulse for each of the plurality of pattern groups.

  According to the present invention, even when intersymbol interference occurs in a reproduction signal as in a high-density optical disc such as an HD-DVD, the reproduction jitter of the reproduction signal can be measured and recorded as an index. Since the laser pulse can be set optimally, information can be recorded on the optical disc with high reliability.

(First embodiment)
FIG. 1 is a conceptual diagram showing the overall configuration of the optical disc apparatus according to the first embodiment of the present invention. In FIG. 1, an optical disc 1 includes a PCA for performing trial writing. The encoding unit 2 performs processing such as error correction code on the input information. The modulator 3 performs processing such as ETM (Eight Twelve Modulation) on the output from the encoder 2. The laser drive unit 4 outputs a semiconductor laser drive signal corresponding to the output from the modulation unit 3 to the optical pickup 5 at the time of recording, and outputs a semiconductor laser drive signal for emitting a laser having a constant intensity to the optical pickup at the time of reproduction. .

  The optical pickup 5 writes and reads information to and from the optical disc 1 by converging the laser light emitted from the semiconductor laser onto the optical disc 1 with an objective lens. In addition, an objective lens actuator that adjusts the convergence state of the laser beam with respect to the optical disc 1, a photodetector that receives the reflected light from the optical disc, and a laser beam emitted from the semiconductor laser is guided to the objective lens, and the reflected light from the optical disc 1 is reflected. An optical system that guides the light to the photodetector.

  The light reception signal processing unit 6 amplifies the light reception signal photoelectrically converted by the photodetector of the optical pickup 5 to generate a reproduction signal, and generates a wobble signal, a focus error signal, a tracking error signal, and the like.

  The servo unit 7 generates a focus servo signal and a tracking servo signal from the focus error signal and tracking signal output from the light reception signal processing unit 6, and outputs them to the optical pickup 5. Further, a motor servo signal is generated from the wobble signal output from the received light signal processing unit 6 and output to the drive motor of the optical disc 1.

  The A / D conversion unit 8 performs A / D conversion on the reproduction signal output from the received light signal processing unit 6 at a predetermined sampling timing, and outputs amplitude value data of the reproduction signal.

  The adaptive equalization unit 9 is composed of an FIR filter, adjusts the filter coefficient, and performs equalization processing so that the reproduced signal conforms to the PR (1, 2, 2, 2, 1) characteristics.

  Since the maximum likelihood decoding unit 10 performs ML decoding of a reproduction signal having PR characteristics, soft decision Viterbi decoding is performed on the amplitude value data of the reproduction signal that is the output of the adaptive equalization unit 9 and compared with a predetermined expected value. The binary data of the reproduction signal is decoded.

  The demodulator 11 performs processing such as ETM demodulation on the binary data of the reproduction signal that is the output of the maximum likelihood decoder 10. The decoding unit 12 performs processing such as error correction on the output of the demodulation unit 11.

  The partial response equalization unit 13 is composed of an FIR filter, and the binary data of the reproduction signal that is the output of the maximum likelihood decoding unit 10 is converted into an amplitude value having ideal PR (1, 2, 2, 2, 1) characteristics. Data.

  The pattern detection unit 14 detects a predetermined pattern group from the binary data of the reproduction signal that is the output of the maximum likelihood decoding unit 10, and notifies the reproduction jitter calculation unit 1501 which predetermined pattern is detected.

  FIG. 2 is a diagram showing classification of a predetermined pattern composed of a mark length nT and a space length mT. Hereinafter, the predetermined pattern group includes a pattern group including a leading edge including a combination of a preceding space length of 2T, 3T, 4T or more and a subsequent mark length of 2T, 3T, 4T or more as shown in FIG. Of the patterns belonging to the pattern group including the trailing edge consisting of a combination of the mark length of 2T, 3T, 4T or more and the subsequent space length of 2T, 3T, 4T or more, excluding the combination pattern of the mark length 2T and the space length 2T, A set of patterns. Further, the predetermined pattern means an arbitrary pattern belonging to a predetermined pattern group.

The control unit 15 includes a reproduction jitter calculation unit 1501 and a laser pulse control unit 1502. In addition, firmware that controls the entire optical disc apparatus is included, and each unit is controlled according to this firmware.
<Outline of playback jitter calculation procedure>
Before describing the specific operation of the reproduction jitter calculation unit 1501, an outline of a calculation procedure of reproduction jitter will be described first.

  FIG. 3 is a diagram illustrating the maximum expected value error (forward shift) of the front edge. Here, the “front edge” corresponds to an edge of a mark that divides the mark from the preceding space.

  In FIG. 3, the binary ideal pattern is (1, 1, 0, 0, 0, 1, 1, 0, 0), that is, a pattern in which the preceding space length is 3T and the subsequent mark length is 2T. As a normalized amplitude value data, -1 is assigned when the pattern is 1, +1 is assigned when the pattern is 0, and partial response equalization of PR (1, 2, 2, 2, 1) is performed as a solid line in FIG. It becomes a waveform shown by.

  Next, a pattern in which the leading edge of the ideal pattern has shifted forward by 1T (1, 1, 0, 0, 1, 1, 1, 0, 0), that is, a pattern in which the preceding space length is 2T and the subsequent mark length is 3T And When PR (1, 2, 2, 2, 1) partial response equalization is performed in the same manner as the ideal pattern, a waveform indicated by a one-dot chain line in FIG. 3 is obtained.

  Here, paying attention to the point where the front edge transitions forward (indicated by a two-dot chain line in FIG. 3), the amplitude value data of the partial response equalization waveform of the ideal pattern at this point and the partial response equalization of the 1T shift pattern The absolute value of the difference between the waveform and the amplitude value data is the maximum expected value error (FME). When the ideal pattern is shifted forward by 1T or less, the absolute value (FD) of the difference between the partial response equalization waveform of the ideal pattern and the partial response equalization waveform of the transition pattern is compared with the maximum expected value error FME By doing so, it can be understood at what rate the channel clock 1T has shifted. That is, the arithmetic expression (FD / FME) × T gives the deviation amount at this time. In order to reduce the local dependence of the deviation amount, it is preferable to take an average with a predetermined number of samples. Therefore, in the present invention, the deviation amount of the front edge is calculated by the arithmetic expression (FE / FME) × T using the arithmetic average of the difference from the partial response equalization waveform of the ideal pattern as the expected value error (FE). .

  Next, the case of the rear edge will be described. FIG. 4 is a diagram showing the maximum expected value error (forward deviation) of the trailing edge. Here, the “rear edge” corresponds to an edge of a mark that delimits a mark and a space following the mark.

  In FIG. 4, when the binary ideal pattern is (0, 1, 1, 1, 1, 0, 0, 0, 1), that is, the recording modulation system channel clock is T, the preceding mark length is 4T, The following space length is 3T. As a normalized amplitude value data, -1 is assigned when the pattern is 1, +1 is assigned when the pattern is 0, and partial response equalization of PR (1, 2, 2, 2, 1) is performed as a solid line in FIG. It becomes a waveform shown by.

  Next, a pattern in which the leading edge of the ideal pattern has shifted forward by 1T (0, 1, 1, 1, 0, 0, 0, 0, 1), that is, a pattern in which the preceding mark length is 3T and the subsequent space length is 4T And When the partial response equalization of PR (1, 2, 2, 2, 1) is performed in the same manner as the ideal pattern, a waveform indicated by a one-dot chain line in FIG. 4 is obtained.

  Here, paying attention to the point where the rear edge transitions forward (indicated by a two-dot chain line in FIG. 4), the amplitude value data of the partial response equalization waveform of the ideal pattern at this point and the partial response equalization of the 1T shift pattern The absolute value of the difference between the waveform and the amplitude value data is the maximum expected value error (RME). In the following, it can be seen how much the deviation has occurred with respect to the channel clock 1T by the same discussion as above. In order to reduce the local dependency of the deviation amount as in the case of the front edge, in the present invention, an arithmetic expression (RE) is obtained by using an arithmetic average of a difference from an ideal pattern partial response equalization waveform as an expected value error (RE). / RME) × T is used to calculate the deviation amount of the trailing edge.

<Operation of Playback Jitter Calculation Unit 1501>
FIG. 5 is a flowchart showing the operation of the reproduction jitter calculation unit 1501.

  When the notification that the predetermined pattern to be processed is detected is received from the pattern detection unit 14, the reproduction jitter calculation unit 1501 causes the edge included in the predetermined pattern to transition forward by 1T (in FIG. 3 or FIG. 4). This is the absolute value of the difference between the amplitude value data of the partial response equalization waveform of the predetermined pattern and the amplitude value data of the partial response equalization waveform of the pattern whose edge has shifted 1T in the forward direction. The maximum expected value error is acquired (S10). Since the maximum expected value error can be uniquely calculated once the pattern is determined, the maximum expected value error may be calculated in advance for a predetermined pattern without being calculated each time, and the result may be held. Hereinafter, the maximum expected value error when the edge included in a given pattern is the front edge, the maximum expected value error (FME) of the front edge, the maximum expected value error of the rear edge, and the maximum expected value error of the rear edge (RME).

Next, the amplitude value data (R) of the point corresponding to the edge included in the predetermined pattern is predicted from the amplitude value data of the reproduction signal output from the adaptive equalization unit 106 (S11). Here, the prediction is when the amplitude value data of the reproduction signal of the sample timing before and after the edge is R1, R2,
R = (R1 + R2) / 2
To do. At the same time, the amplitude value data (I) of the point corresponding to the edge included in the predetermined pattern is predicted from the partial response equalization amplitude value data of the reproduction signal output from the partial response equalization unit 13 (S11). Here, the prediction is when the partial response equalization amplitude value data of the reproduction signal of the sample timing before and after the edge is I1, I2,
I = (I1 + I2) / 2
To do.

  Next, with reference to the amplitude value data I predicted from the partial response amplitude value data of the reproduction signal, the expected value error (E) of the amplitude value data R predicted from the amplitude value data of the reproduction signal with respect to this reference value is calculated. (S12). Here, the expected value error E is N when the total number of predetermined patterns to be processed is N.

により算出する。なお、期待値誤差Eは、所定のパターンに含まれるエッジが前エッジの場合と、後エッジの場合とで個別に算出し、それぞれ前エッジの期待値誤差（FE）および後エッジの期待値誤差（RE）とする。

Calculated by Note that the expected value error E is calculated separately for the case where the edge included in the predetermined pattern is the front edge and the case of the back edge, and the expected value error (FE) of the front edge and the expected value error of the back edge, respectively. (RE).

Next, the reproduction jitter of the front edge and the rear edge is calculated using the respective maximum expected value error and expected value error (S13). The playback jitter is expressed as the amount of deviation with respect to the channel clock T, and the playback jitter (FJ) at the leading edge is
FJ = FE / FME × T
The trailing edge playback jitter (RJ) is
RJ ＝ RE / RME × T
Calculated by
The above processing is performed for each predetermined pattern belonging to the predetermined pattern group, and the calculated reproduction jitter is output to the laser pulse control unit 1502.
<Overview of strategy>
FIG. 6 is a diagram showing a recording laser pulse strategy. Four power levels of Pw, Pb1, Pb2, and Pb3 are set as the power level of the recording laser pulse. The recording laser pulse is multipulsed as shown in FIG. 6, and the leading edge pulse rises at the time when Tsfp has elapsed with respect to the rising edge of the recording mark, and rises at the time when Tefp has elapsed with respect to the rising edge of the recording mark. Go down. The trailing edge pulse rises at a time when Tslp has elapsed, and falls at a time when only Telp has elapsed, with reference to a time preceding the falling of the recording mark by T. Following the trailing edge pulse, there is a portion where the power level is Pb2 by Tlc.

Note that the parameter values such as the power levels Pw, Pb1, Pb2, Pb3 and times Tsfp, Tefp, Tmp, Tslp, Telp, and Tlc that define the multipulse shown in FIG. It is recorded on the information track of the control data zone of the optical disc 1. Hereinafter, the operation of the recording pulse controller 1502 will be described with reference to FIG.
<Operation of Laser Pulse Control Unit 1502>
The recording pulse control unit 1502 reads a parameter value relating to the recording laser pulse from the information track of the control data zone of the optical disc 1, determines the recording laser pulse strategy by initializing the parameter value, outputs it to the laser driving unit 4, and outputs it to the laser driving unit 4. Test writing is performed with the PCA of the optical disc 1 using a test pattern including the pattern group.

  Next, the portion where the trial writing has been performed is reproduced, and the reproduction jitter of the front edge and the rear edge of a predetermined pattern group is received from the reproduction jitter calculation unit 1501. When the reproduction jitter values of the front edge and the rear edge of the predetermined pattern group are equal to or larger than the predetermined value, the strategy of the recording laser pulse for recording the corresponding predetermined pattern is updated. That is, the leading edge rise is delayed by the leading edge reproduction jitter, and the trailing edge trailing edge is delayed by the trailing edge reproduction jitter. That is, Tsfp is updated as Tsfp = Tsfp + FJ when delaying the leading edge rising edge, and Telp is updated as Telp = Telp + RJ when trailing edge trailing edge is delayed. When Tsfp is updated, Tefp may be updated as Tefp = Tefp + FJ. When Telp is updated, Tslp may be updated as Tslp = Tslp + RJ.

  Trial writing is performed with the updated strategy, and this operation is repeated until the reproduction jitter values of the front edge and rear edge of the reproduced predetermined pattern group become smaller than the predetermined value.

  The case where the edge included in the predetermined pattern has transitioned to the front has been described above. When the edge included in the predetermined pattern transitions in the backward direction, the leading edge of the leading edge is advanced by the leading edge reproduction jitter, and the trailing edge of the trailing edge is preceded by the trailing edge reproduction jitter. That is, Tsfp is updated as Tsfp = Tsfp-FJ when the leading edge of the leading edge is advanced, and Telp is updated as Telp = Telp-RJ when the trailing edge of the trailing edge is delayed. When Tsfp is updated, Tefp may be updated as Tefp = Tefp-FJ. When Telp is updated, Tslp may be updated as Tslp = Tslp-RJ.

According to such a 1st embodiment of the present invention, the following operation effects can be enjoyed.
(1) The amplitude value data of the reproduction signal at a predetermined sampling timing is acquired by the A / D conversion unit 8, Viterbi decoding is performed on the amplitude value data of the reproduction signal by the maximum likelihood decoding unit 10, and the binary data of the reproduction signal is obtained. Then, the partial response equalization unit 13 converts the binary data of the reproduction signal into amplitude value data of an equalized signal having ideal PR (1, 2, 2, 2, 1) characteristics, and the pattern detection unit 14 determines a predetermined value. The reproduction jitter calculation unit 1501 calculates the reproduction jitter from the expected value error of the amplitude value data of the edge reproduction signal with respect to the amplitude value data of the mark edge equalization signal included in the predetermined pattern, and the laser Since the pulse control unit 1502 sets the waveform of the recording laser pulse based on the reproduction jitter, the recording laser pulse is output even when there is intersymbol interference in the reproduction signal. Can be used reproduction jitter as an index for optimizing, it is possible to reliably information recorded on the optical disk.
(2) The reproduction jitter calculation unit 1501 predicts the amplitude value data I of the mark edge equalization signal and the amplitude reproduction data R of the edge reproduction signal included in the predetermined pattern, and obtains a difference value by an arithmetic expression IR. Since the expected value error E is calculated by averaging these values, it is possible to measure the reproduction jitter, which is a deviation in the time axis direction, with the expected value error, which is a deviation in the amplitude axis direction. .
(3) The reproduction jitter calculation unit 1501 converts the amplitude value data of the equalized signal of the edge when the partial response equalization is performed on the predetermined pattern and the pattern in which the edge is shifted by T in the predetermined pattern. For the partial response equalization, the absolute value of the difference from the amplitude value data of the edge equalized signal is taken as the maximum expected value error, and the edge reproduction jitter is calculated by the equation (E / ME) x T Therefore, it is possible to accurately measure the reproduction jitter as the deviation amount with respect to the channel clock T.
(4) When the laser pulse control unit 1502 determines that the front edge has deviated from a predetermined position due to an expected value error of the front edge of the mark, the laser pulse control unit 1502 determines the leading pulse waveform of the laser pulse based on the reproduction jitter of the front edge. Since the adjustment is set, the mark can be recorded on the optical disc 1 with high reliability by compensating for the deviation of the front edge.
(5) When the laser pulse control unit 1502 determines that the trailing edge is deviated from a predetermined position due to the expected value error of the trailing edge of the mark, the trailing pulse waveform of the laser pulse is determined by the reproduction jitter of the trailing edge. Therefore, it is possible to record the mark on the optical disc 1 with high reliability by compensating for the deviation of the trailing edge.
(6) Since the reproduction jitter calculation unit 1501 calculates the reproduction jitter for each predetermined pattern group, the reproduction jitter calculation accuracy is improved.
(7) Since the laser pulse control unit 1502 sets the laser pulse waveform for each predetermined pattern group, the reliability when the mark is recorded on the optical disc 1 is improved.
(Second Embodiment)
In the first embodiment, has been described a case where an edge included in a predetermined pattern has been found that a transition in advance either direction. By the way, it is possible to determine the direction of edge transition by referring to the sign of the expected value error of the edge included in the predetermined pattern. The outline of the procedure for determining the edge transition direction will be described below.

<Outline of judgment procedure of edge transition direction>
FIG. 7 is a diagram illustrating the maximum expected value error (backward shift) of the front edge. In FIG. 7, the 1T shift pattern in which the front edge is shifted 1T backward is (1, 1, 0, 0, 0, 0, 1, 0, 0), that is, the preceding space length is 5T, and the subsequent mark length is 1T. This is different from FIG. When the relationship between the partial response equalization waveform of the ideal pattern and the partial response equalization waveform of the 1T shift pattern at the point at which the front edge transitions in the front-rear direction is compared in FIG. 3 and FIG. Is based on the partial response equalization waveform of the ideal pattern. When the amplitude value data of the partial response equalization waveform of the 1T shift pattern decreases and the front edge transitions backward, the partial response equalization of the 1T shift pattern is performed. It can be seen that the amplitude value data of the waveform is large. This indicates that it is possible to determine whether the front edge has shifted forward or backward by referring to the sign of the expected value error of the front edge.

FIG. 8 is a diagram illustrating the maximum expected value error (rear shift) of the rear edge. In FIG. 8, the 1T shift pattern in which the rear edge is shifted 1T backward is (0, 1, 1, 1, 1, 1, 0, 0, 1), that is, the preceding mark length is 5T, and the subsequent space length is 2T. This is different from FIG. Hereinafter, it can be understood from the discussion similar to the above that it is possible to determine whether the rear edge has shifted forward or backward by referring to the sign of the expected value error of the rear edge.
<Strategy when edge transition direction is determined>
The following describes the strategy when the edge is not known that the transition in advance either direction.

  If it is determined that the edge has moved forward by referring to the sign of the expected value error of the edge, the strategy is updated according to the procedure when the edge has moved forward in the first embodiment. When it is determined that the direction has been changed, the strategy is updated according to the procedure in the case where the edge has changed backward in the first embodiment.

  Here, when the sign of the expected value error of the front edge is negative, it is determined that the front edge has transitioned in the forward direction, and when the sign is positive, it is determined that the front edge has transitioned in the backward direction. Further, when the sign of the expected value error of the rear edge is positive, it is determined that the rear edge has shifted forward, and when the sign is negative, it is determined that the rear edge has transitioned backward.

According to such a 2nd embodiment of the present invention, in addition to a 1st embodiment, the following operation effects can be enjoyed.
(8) When the laser pulse control unit 1502 determines that the deviation of the front edge is the forward direction, the laser pulse control unit 1502 delays the rising edge of the leading pulse of the laser pulse by FJ, and determines that the deviation of the front edge is the backward direction. Since the leading edge of the laser pulse is advanced by FJ, it is possible to compensate the mark transition due to the reproduction jitter of the front edge and to record the mark on the optical disc 1 with high reliability.
(9) When determining that the trailing edge shift is in the forward direction, the laser pulse control unit 1502 delays the trailing edge pulse falling by RJ, and determines that the trailing edge shift is in the backward direction. In this case, since the rising edge of the rear end pulse of the laser pulse is preceded by RJ, it is possible to record the mark on the optical disc 1 with high reliability by compensating for the transition of the mark due to reproduction jitter at the rear edge.
(10) The laser pulse controller 1502 determines the direction of deviation of the leading edge based on the sign of the expected value error of the leading edge, and determines the direction of deviation of the trailing edge based on the sign of the expected value error of the trailing edge. The prediction reliability of the direction of edge transition is improved.

  Although the best mode for carrying out the present invention has been described above, the present invention is not limited to the configuration of this embodiment, and the scope of application of the present invention defined in the claims. As long as the functions of the configuration of the above-described embodiment can be achieved, various modifications are possible.

  For example, in the embodiment of the present invention, the laser pulse control unit 1502 sets the laser pulse based on the reproduction jitter at the edge of the mark calculated by the reproduction jitter calculation unit 1501, but the predetermined number of marks included in the predetermined pattern is determined. The waveform of the laser pulse may be set based on the expected value error of the amplitude value data of the edge reproduction signal with respect to the amplitude value data of the equalized signal at this point. FIG. 9 is a diagram showing a reproduction signal and an equalization signal when the mark length is 8T. According to the present modification, the long mark length pattern shown in FIG. 9 has a small deviation in the time axis direction, but even when the deviation in the amplitude axis direction is large, the strategy for compensating for it is performed. The mark can be recorded on the optical disc 1 with high reliability.

  In the embodiment of the present invention, the laser pulse control unit 1502 sets the waveform of the laser pulse every time the reproduction jitter is calculated. If the reproduction jitter exceeds a predetermined value, the laser pulse control unit 1502 sets the laser pulse waveform. The waveform may not be set or may be returned to the initial value. According to this modification, the strategy can be updated stably.

  In the embodiment of the present invention, the laser pulse control unit 1502 reads the parameter value related to the recording laser pulse from the information track in the control data zone of the optical disc 1 and uses it as the initial value of the strategy. The final strategy may be recorded on the optical disc 1 together with an identifier for identifying the optical disc apparatus 100. If this strategy exists on the optical disc 1, this may be read out and used as the initial value of the strategy. According to this modification, the time can be shortened until the strategy is determined.

  According to the present invention, even when intersymbol interference occurs in a reproduction signal as in a high-density optical disc such as an HD-DVD, the reproduction jitter of the reproduction signal can be measured and recorded as an index. Since the laser pulse can be set optimally, it has the effect of recording information on the optical disk with high reliability, and is useful as an optical disk apparatus.

1 is a conceptual diagram showing the overall configuration of an optical disc apparatus according to an embodiment of the present invention. The figure which shows the classification of the predetermined pattern which consists of mark length nT and space length mT Diagram showing maximum expected value error (forward deviation) of front edge Diagram showing maximum expected value error (forward deviation) of rear edge Flow chart showing the calculation procedure of reproduction jitter Diagram showing recording laser pulse strategy Diagram showing maximum expected value error (backward deviation) of front edge Diagram showing maximum expected value error (backward deviation) of rear edge The figure which shows the reproduction signal and equalization signal when mark length is 8T

Explanation of symbols

8 A / D conversion unit 9 Adaptive equalization unit 10 Maximum likelihood decoding unit 13 Partial response equalization unit 14 Pattern detection unit 1501 Reproduction jitter calculation unit 1502 Laser pulse control unit

Claims (6)

In an optical disc apparatus that records and reproduces information on a disc using laser light,
Reproduction amplitude value data acquisition means for acquiring amplitude value data of a reproduction signal at a predetermined sampling timing, maximum likelihood decoding means for decoding the binary data by performing maximum likelihood decoding on the amplitude value data, and partial to the binary data An equalized amplitude value data output means for generating an equalized signal by performing response equalization and outputting amplitude value data of the equalized signal, a pattern detecting means for detecting a predetermined pattern, the predetermined pattern, etc. An optical disk apparatus comprising: laser pulse setting means for setting a waveform of a recording laser pulse composed of one or more pulse trains based on the converted amplitude value data and the reproduction amplitude value data. Reproduction jitter calculating means for calculating reproduction jitter of the edge of the mark included in the predetermined pattern,
The reproduction jitter calculation means expects the mark edge reproduction amplitude value data for the mark edge equalization amplitude value data from the mark edge equalization amplitude value data and the edge reproduction amplitude value data included in the predetermined pattern. 2. The optical disc apparatus according to claim 1, wherein a value error (E) is calculated, and the reproduction jitter is calculated based on the expected value error.   When the laser pulse setting means determines that the front edge is deviated from a predetermined position due to an expected value error (FE) of the front edge of the mark, the laser pulse setting means uses the reproduction jitter (FJ) of the front edge to 3. The optical disk apparatus according to claim 2, wherein the tip pulse waveform of the laser pulse is adjusted and set.   When the laser pulse setting means determines that the rear edge is deviated from a predetermined position due to an expected value error (RE) of the rear edge of the mark, the laser pulse setting means uses the reproduction jitter (RJ) of the rear edge to 3. The optical disc apparatus according to claim 2, wherein the trailing edge pulse waveform of the laser pulse is adjusted and set.   The information is divided into a plurality of pattern groups consisting of a mark length nT (n is an integer of 1 or more) and a space length mT (m is an integer of 1 or more), and the reproduction jitter calculation means 5. The optical disc apparatus according to claim 2, wherein reproduction jitter is calculated as follows. 6. The optical disc apparatus according to claim 1, wherein the laser pulse setting unit sets a waveform of the laser pulse for each of the plurality of pattern groups.

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