JP2007059012A - Method for controlling waveform equalization, optical disk system, and waveform equalization circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device and a waveform equalization circuit which quickly carries out reduction of a reproduction data quantity required for error convergence and convergence of an FIR filter coefficient in the case of carrying out adaptive equalization processing by the optical disk system. <P>SOLUTION: The optical disk device and the waveform equalization circuit are composed of at least a control means for controlling starting and stopping of the adaptive equalization processing, an FIR filter where a tap coefficient value can be changed, a means for discriminating error convergence of the output of the FIR filter and an equalization target value, a storage means for holding the tap coefficient value temporarily, and a generation means of the tap coefficient value with respect to the FIR filter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a waveform equalization control method, an optical disc apparatus, and a waveform equalization circuit that perform adaptive equalization processing on a reproduction signal read from an optical disc.

  In recent years, high-speed recording / playback technology for DVDs and high-density discs such as Blu-ray discs have been developed, and the quality (S / N, amplitude) of the disc playback signal has increased with higher-speed playback and higher density (short mark recording). ) Tends to deteriorate. Under such circumstances, the PRML (Partial Response Maximum Likelihood) method is being adopted in the optical disc apparatus for the purpose of improving the reproduction reliability of the optical disc. PRML is composed of a PR equalizer composed of a FIR (Finite Impulse Response) filter and a Viterbi decoder composed of various arithmetic circuits such as a branch metric, path metric, and path memory update (see Patent Document 1).

On the other hand, adaptive equalization processing for the purpose of further improving the reproduction reliability with respect to the PRML system has begun to be adopted in recent optical disc apparatuses. The adaptive equalization processing is performed by correcting the reproduction signal by controlling the tap coefficient that determines the characteristics of the FIR filter, and the LMS (Least Mean Square) algorithm is generally used as the control algorithm. The basic formula is shown in Formula (1).
Ci (n + 1) = Ci (n)-. Mu..times.e (n) .times.x (ni) (1) The right side Ci (n) is the value of each tap coefficient constituting the FIR filter at time (n). Where i represents each tap position of the FIR filter. μ is an attenuation rate indicating the update rate of the tap coefficient value, e (n) is an error between the FIR filter output and the teacher (target) signal, and x (ni) is an FIR filter input for each tap position. A tap coefficient value Ci (n + 1) at time (n + 1) is obtained. By updating the tap coefficient value according to this calculation, the error e (n) is attenuated, and the FIR filter output value approaches the target level. That is, FIR filter characteristics are adjusted according to the reproduction signal to improve reproduction reliability (see Patent Document 2).

JP-A-10-326456 JP 2001-189052 A (page 3)

  In adaptive equalization processing, the minimum amount of playback data required until error convergence is determined according to the attenuation rate μ in equation (1). Usually, the attenuation rate is set to about 1/1000 to 1/10000, and the FIR filter Stabilize the coefficient update. Accordingly, a considerable amount of reproduction data is required until error convergence, that is, until the tap coefficient value for the reproduction signal converges to an appropriate value. For example, when the attenuation factor is 1/10000, in order for the tap coefficient value to change by one step, it is necessary to input reproduction data of at least 10000 samples to the FIR filter, and until the tap coefficient value converges to an appropriate value. Requires several times to several tens of times the input and calculation of reproduction data. When the adaptive equalization processing is applied to the optical disc apparatus, reproduction from the reproduction target position on the disc needs to seek before the amount of data required for convergence. Therefore, there is a problem that the access time increases in order to perform reproduction while obtaining the improvement effect of the reproduction signal by the adaptive equalization processing.

  On the other hand, there may be a case where the reproduction signal immediately after seeking has deteriorated. In this case, even if seek is performed in consideration of the amount of playback data necessary for convergence, the error rate may not be improved by reaching the target position before the playback signal can be improved by adaptive equalization processing. There is.

  Further, in the case of a write once type and rewritable type optical disc, the recording quality may vary depending on the disc radial position. For example, it means that the tap coefficient value for convergence is different between the inner peripheral region and the outer peripheral region, and the same problem as described above occurs.

  In addition, there is a disc having a special structure for each access unit. As an example, a sector of a DVD-RAM playback unit is roughly divided into a PID area that is formed by pre-pits and includes a PID area that includes address information, and a user data (UD) area that rewrites the recorded information by forming a recording mark made of phase change material. The That is, there are regions having different compositions and reproduced signal qualities on the same disc, and control for performing adaptive equalization processing for each region becomes a problem.

  An object of the present invention is to provide a waveform equalization control method, an optical disc apparatus, and a waveform equalization circuit that solve the above-mentioned problems particularly for an optical disc apparatus.

  The control method for solving the above-described problems in the present invention starts updating the tap coefficient value of the FIR filter in response to the start of the adaptive equalization process, converges the error between the FIR filter output and the equalization target value, adapts, etc. The tap coefficient value is held in response to the stop of the equalization process, the tap coefficient value is output to the FIR filter again in response to the start of the process, and the adaptive equalization process is restarted from the coefficient value. Is done.

  On the other hand, the optical disc apparatus and the waveform equalization circuit include at least control means for controlling start and stop of adaptive equalization processing, an FIR filter capable of changing tap coefficient values, an FIR filter output, and an equalization target value. A determination unit that determines error convergence, a storage unit that temporarily holds a tap coefficient value, and a tap coefficient value generation unit for the FIR filter are provided.

  On the other hand, a control method for solving the problem at the time of reproducing an optical disk in which an access unit is composed of first and second areas starts updating tap coefficients for the FIR filter in response to the start of adaptive equalization processing. Based on the first and second area identifications, the first and second tap coefficients are retained, and based on the first and second area identifications, the retained first and second tap coefficients are retained at the head of each area. The problem is solved by outputting a numerical value to the FIR filter and further performing adaptive equalization processing from the coefficient value.

  Further, the optical disc apparatus and waveform equalization circuit corresponding to the optical disc playback constituting the access unit in the first and second areas, at least the control means for controlling the start and stop of the adaptive equalization processing, the change of the tap coefficient value A possible FIR filter, a determination means for determining error convergence between the FIR filter output and the equalization target value, a first storage means for holding a tap coefficient for the first area, and a tap coefficient for the second area. Second storage means for holding, identification means for performing first and second area identification on the optical disk reproduction signal, and tap coefficient value generation means for the FIR filter are provided.

  According to the present invention, it is possible to reduce the amount of reproduction data and the access time required until the tap coefficient of the FIR filter converges. In addition, the error rate after data demodulation can be suppressed immediately after re-access.

  Embodiments of the present invention will be specifically described below.

  First, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram when the waveform equalization control method of the present invention is applied to an optical disc apparatus, and FIG. 4 is a state transition diagram showing a control method for the tap coefficient of the FIR filter circuit in the apparatus of FIG.

In FIG. 1, 1 is an optical disc, 2 is an optical head for reading a recording mark and pit on the optical disc 1, 3 is a preamplifier for amplifying a signal with respect to the return light from the optical disc and outputting it as a reproduction signal, 4 is a preamplifier 3 ADC that samples the playback signal from 1T (T is a natural number and is a channel bit indicating the minimum unit for recording mark and pit length) and converts the sample value to a digital value. A DPLL circuit that controls the clock frequency so that the phase error between the later reproduction signal and the oscillation clock is minimized, 6 is an FIR filter circuit that can arbitrarily set the tap coefficient, and can change the filter frequency characteristic according to the set coefficient, 7 is a Viterbi decoding circuit for realizing the Viterbi decoding algorithm, and 8 is included in the NRZI signal (non-return to zero inverted) of the Viterbi decoding output. A data demodulating circuit that obtains original reproduction information by detecting and demodulating a synchronization signal transmitted rarely, 9 decodes a PR (Partial Response) code from the NRZI signal, and equalizes the decoded PR code It is a target selection circuit that selectively outputs a target value. Equalization target values are 7 values of PR code (NRZI bit string) “0000”, “0001/1000”, “0011/1100”, “0111/1110”, “1111”, “0110”, “1001” 10 is an error calculation circuit for calculating a target miscalculation from the equalization target value for NRZI and the output of the FIR filter circuit 6. The target error is, for example, K samples (K is a positive integer of 2 or more) Is the average value.
11 is a convergence determination circuit that determines error convergence by comparing a target error with a threshold value, 12 is a coefficient holding circuit that temporarily holds a tap coefficient value for the FIR filter circuit 6, 13 is a target error and FIR filter circuit input, and attenuation This is a coefficient control circuit that performs a calculation according to the LMS algorithm (1) from the calculation result of the rate μ and the tap coefficient for the FIR filter circuit 6 to newly generate a tap coefficient.

  Control of adaptive equalization processing in the optical disc apparatus of FIG. 1 will be described using the state transition diagram of FIG. In FIG. 4, the optical head 2 accesses the reproduction target position on the optical disc 1 (S41). The clock frequency control is performed on the reproduced signal via the preamplifier 3 and the ADC 5 so that the phase error between the input signal and the oscillation clock is minimized in the DPLL circuit 5. A DPLL lock signal is generated by the convergence of the phase error by frequency control. The coefficient control circuit 13 starts updating the tap coefficient of the FIR filter circuit 6 by adaptive equalization processing according to the LMS algorithm in response to the DPLL lock detection. Further, the FIR filter circuit output undergoes Viterbi decoding and data demodulation processing (S42). When the FIR filter circuit output approaches each equalization target value by the adaptive equalization processing and the convergence determination circuit 11 detects (target error value) ≦ (convergence threshold) and error convergence is detected, the coefficient is held via the coefficient control circuit 13. The tap coefficient holding is controlled for the circuit 12 (S43). The coefficient holding circuit 12 holds an optimum tap coefficient at the time of error convergence, that is, with respect to the FIR filter circuit input. Thereafter, the adaptive equalization control continues, and a new tap coefficient value is held in the coefficient holding circuit 12 every time error convergence is detected (S43). On the other hand, in S42, when the reproduction signal is suddenly deteriorated due to a DPLL lockout generated as a result of the phase error in the DPLL circuit 5 gradually increasing or a scratch on the optical disk 1 or the like (control stop factor in FIG. 1). (Detection), the coefficient control circuit 13 stops updating the tap coefficient (S44). An increase in the phase error in the DPLL circuit corresponds to a gradual deterioration of the reproduction signal. After that, when DPLL lock-in detection or a scratch on the disk is passed again (control stop factor is canceled), when a new access to the optical disk is made, the coefficient control circuit 13 sets the tap coefficient held by the coefficient holding circuit 12. Reload (S45), output to the FIR filter circuit 6, and start adaptive equalization processing from the reloaded coefficient value (S42).

  In the first embodiment described above, the tap coefficient at the time of error convergence by adaptive equalization control is retained after detection of the DPLL lock in the DPLL circuit, and a new access is made when returning from the DPLL lockout or abnormal reproduction signal. Sometimes, the retained tap coefficient value is output as an FIR filter coefficient, and the adaptive equalization process is restarted from the coefficient value, so that it is possible to reduce the amount of reproduction data and time required until error convergence. Furthermore, since an excellent FIR filter output can be obtained immediately after the return, the target level selection is appropriately performed in the target selection circuit 9 that uses the Viterbi output, so that the adaptive equalization process is stably performed. Further, the error rate after the data demodulation process can be reduced immediately after the return.

  Note that the convergence determination circuit 11 is not limited to the convergence determination based on the comparison between the target error and the threshold value, and may hold the tap coefficient at regular intervals. In this case, the effect is limited to the case of sudden reproduction signal deterioration due to scratches on the disk. This is because the reproduction signal is normal immediately before the sudden deterioration of the reproduction signal. In this case, the tap coefficient update in the coefficient control circuit 13 may be simply held for the abnormal period without using the coefficient holding circuit 12.

  The second embodiment of the present invention will be described below with reference to the drawings.

  FIG. 2 is a second block diagram when the waveform equalization control method of the present invention is applied to an optical disk apparatus. Reference numeral 1 denotes an optical disk which constitutes an access block unit by a pre-pit area and a recording area. As an example, a DVD-RAM Is mentioned. Reference numeral 14 denotes a UD part coefficient holding circuit for holding the tap coefficient for the recording area, and 15 denotes a PID part coefficient holding circuit for holding the tap coefficient for the pre-pit area. The other symbols are the same as those in FIG.

  The structure of the optical disc 1 to be subjected to adaptive equalization control in FIG. 2 and the necessary control signals will be described with reference to FIG. FIG. 5A shows a data structure of a DVD-RAM as an example of an optical disk that constitutes an access block unit by a pre-pit area and a recording area. In the figure, the block structure includes an area (PID1 to 4) including address information necessary for accessing a target position on the optical disk, a pre-pit portion including VFO1 and 2 areas for clock pull-in by DPLL, and user data. It consists of a recording unit consisting of a (UD) area, a VFO 3 for clock acquisition, and a Guard / Buffer area for protecting the user data area.

  FIG. 5B shows control timings for controlling the start and stop of phase comparison for the DPLL circuit 5. The DPLL circuit starts phase comparison in each section and detects DPLL lock detection. The control timing covers the area from PID2 from the beginning of the prepit part in FIG. 5A, the area from VFO1 to MIRR after PID2, and the area from VFO3 to Guard2 in the phase change recording part. The DPLL circuit 6 switches the optimum PLL gain for each section of the timing signal to control clock pull-in, and outputs DPLL lock-in detection to the coefficient control circuit 13. Therefore, the updating and stopping of the tap coefficient in the coefficient control circuit 13 is controlled according to the DPLL lock detected in each section of the PID part and the UD part. FIG. 5C shows the switching timing of the PID part and the UD part. The coefficient control circuit 13 selects the holding coefficient of the PID part for the PID section and selects the holding coefficient of the UD part for the UD section.

  5D and 5D show the tap coefficient output and latch switching timing of the PID section and UD section performed in the coefficient control circuit 13. (D) -1 indicates the end of the PID section with respect to the switching timing of (C), and the final tap coefficient of the adaptive equalization processing for the PID section is controlled to be latched in the PID section coefficient holding circuit 15, while the UD section The tap coefficient for the UD section is reloaded from the coefficient holding circuit 15 and output to the FIR filter circuit 6, and after the DPLL lock is detected, the adaptive equalization processing for the UD section is started from the reload coefficient value. Similarly, at the boundary between the UD part and the PID part, in (D) -2, the end of the UD section is detected, and the final tap coefficient of the UD section is latched in the UD part coefficient holding circuit 14, while the PID part coefficient holding circuit 15 The tap coefficient for the PID section is reloaded and output to the FIR filter circuit 6, and after the DPLL lock is detected, adaptive equalization processing for the PID section is started from the reload coefficient value.

  In the second embodiment described above, when adaptive equalization processing is performed on an optical disk having a structure in which areas are separated in units of access, adaptive and the like is performed from each tap coefficient value held for each area at the tip of each area. By restarting the equalization control, adaptive equalization processing corresponding to each region can be appropriately performed.

  In the second embodiment, the tap coefficient holding at the time of error convergence is not described, but the convergence determination circuit described in FIG. 1 is provided, and convergence detection is performed according to the PID / UD switching timing in FIG. It is also conceivable to identify the area (PID / UD section) and control the latches to the UD part and PID part coefficient holding circuits 14 and 15.

  Further, even when the control timing of FIG. 5B is input to the coefficient control circuit 13, the same operation and effect can be obtained. In this case, the coefficient control circuit detects the DPLL lock in each section of the control timing, and controls the start and stop of the adaptive equalization process.

  In addition to the configuration of FIG. 2, the coefficient control circuit is provided with two systems, a PID unit and a UD unit, and the tap coefficient output to the FIR filter circuit 6 is switched according to the switching timing of FIG. It may be possible to realize an equivalent function by controlling the updating of the tap coefficient by detecting the DPLL lock in the PID section and UD section.

A third embodiment of the present invention will be described below with reference to the drawings.
FIG. 3 is a third block diagram when the waveform equalization control method of the present invention is applied to an optical disc apparatus. 17 is a first coefficient holding circuit, 18 is a second coefficient holding circuit, 19 is an OR circuit, Reference numeral 20 denotes a system controller. Other reference numerals are the same as those in FIG. In FIG. 3, the coefficient control circuit 13 selects the first coefficient holding circuit 17 and the second coefficient holding circuit 18 at the time of tap coefficient latching or reloading according to the coefficient selection instruction from the system controller. On the other hand, the coefficient latch instruction is an OR between the result of convergence detection by the convergence determination circuit 11 and the instruction from the system controller 20. The third embodiment is based on the assumption that, when performing continuous playback of a series of recording tracks existing on an optical disc, the correction effect of the playback waveform by adaptive equalization processing is used in the retry processing for blocks in which playback is impossible. Explained.

  The tap coefficient holding and reload control in the apparatus of FIG. 3 will be described with reference to the state transition diagram of FIG. In FIG. 6, S61 and S62 are the same as S41 and S42 in FIG. When the tap coefficient update is started in S62 and error convergence is detected, or when the system controller 20 detects the reproduction stop for the optical disc 1, the first tap coefficient is held in the first coefficient holding circuit 17, for example, by a coefficient latch instruction. (S63). The coefficient selection instruction is instructed to the coefficient control circuit 13 by the system controller 20 in advance. After the coefficient is held in the first coefficient holding circuit 17, the coefficient selection instruction is switched to the second coefficient holding circuit 18. Further, once error convergence is detected and error convergence is detected again, or when reproduction of a track for which reproduction has been resumed is completed, the coefficient selection circuit 16 holds the second tap coefficient with respect to the second coefficient holding circuit 18. (S64).

  Further, the reproduction is continued, and when it is determined that the reproduction is impossible due to the error correction process following the data demodulation process, etc., the apparatus performs a retry process that tries to reproduce again the block that has become unreproducible under the control of the system controller 20. Transition (S65). At the time of the first retry 1, for example, by reloading the tap coefficient held in the second coefficient holding circuit 18 (S66), the adaptive equalization process is restarted from the second tap coefficient value (S62). When it is determined that the reproduction is not possible in the reproduction by retry 1 (S65), the process proceeds to retry 2 and the first tap coefficient value is reloaded (S67) in the first coefficient holding circuit 17 to the first tap coefficient value. The adaptive equalization process is resumed from (S62). After that, when the number of retries is exceeded, the process is terminated as being uncorrectable.

  In the third embodiment described above, a plurality of tap coefficients are retained when error convergence is detected during playback of continuous recording tracks or when playback is temporarily stopped, and retry processing is performed after restarting playback. If the error occurs, the number of tap systems retained each time the retry process is repeated is reloaded, and the adaptive equalization process is restarted, thereby reducing the amount of playback data required until error convergence and making the block unreproducible Can be reproduced using the correction effect of the reproduced waveform by the adaptive equalization processing.

  Also in the third embodiment, as in the second embodiment, the first coefficient control circuit and the second coefficient control circuit are provided separately, and the system controller 20 switches the tap coefficient output to the FIR filter circuit 6 to achieve the same. It is conceivable to realize the function.

  It is also conceivable that the system controller 20 monitors the target error during the adaptive equalization process as needed and detects a reproduction abnormality by comparison with a threshold value. This indicates that the FIR filter circuit output by the adaptive equalization process is far away from the equalization target value, and it is determined that the reproduction signal is abnormal or the adaptive equalization process is out of control. In this case as well, it may be possible to transit to the retry process (S65), reload the tap coefficient held at the time of error convergence, and restart the reproduction by the adaptive equalization process.

The fourth embodiment of the present invention will be described below with reference to the drawings.
FIG. 7 is another state transition diagram for explaining tap coefficient holding and reload control using the configuration of the optical disk apparatus of FIG. The states S71 and S72 in FIG. 7 are the same as S61 and S62 in FIG. In the third embodiment, the radial direction on the optical disk is virtually divided into, for example, an inner circumference side and an outer circumference side, and the correction effect of the reproduction waveform by adaptive equalization processing is used when accessing each area. I will explain it on the premise. The area division on the optical disk is performed by the system controller 20, and the determination of the area with respect to the reproduction target position is also performed by the system controller 20.

  In S72, tap coefficient updating is started, and when error convergence is detected or playback stop for the optical disk 1 is detected by the system controller 20, the system controller 20 controls the holding of the tap coefficient according to the access position to the optical disk 1. For example, when accessing the inner peripheral area, the first coefficient holding circuit 17 holds the inner peripheral tap coefficient (S73), and in the outer peripheral area, the second coefficient holding circuit 18 receives the outer peripheral tap coefficient. Hold (S74). When the access to the optical disc 1 occurs again after the end of holding the tap coefficients for the inner circumference side, the outer circumference side, or both areas (S75), the system controller 20 sets the tap coefficient to be reloaded to the coefficient control circuit 13 according to the re-access destination area. Make a selection. When the re-access destination is the inner peripheral side, the tap coefficient on the inner peripheral side is reloaded from the first coefficient holding circuit 17 (S76), and when the reaccess destination is the outer peripheral side, the tap coefficient on the outer peripheral side from the second coefficient holding circuit 18 is reloaded. Is reloaded (S77). After reloading the coefficient, the adaptive equalization process is performed to update the tap coefficient and the reproduction by the data demodulation process is performed (S72). When convergence is detected in S72 or at the end of playback, tap coefficients are held according to the area being accessed (S73, S74).

  In the fourth embodiment described above, a plurality of coefficient holding circuits are used to hold tap coefficients when adaptive equalization processing is performed on different areas on the optical disc, and according to the access destination area at the time of re-access. Then, by selecting the held tap coefficient and using it as the tap coefficient of the FIR filter circuit 6, the adaptive equalization process can be started from an appropriate coefficient value corresponding to the region, and the reproduction data necessary for the error convergence of the adaptive equalization process The amount can be reduced.

  It should be noted that the inner and outer tap coefficient holding in the fourth embodiment is not limited to being held by the first and second coefficient holding circuits in FIG. 3, but at the time of error convergence or at the end of reproduction. Reading from the coefficient control circuit 13 and managing on the memory provided in the system controller 20 is also conceivable.

  As an application of the same configuration and control as in the fourth embodiment, it may be possible to hold a tap coefficient for each reproduction linear velocity of the optical disk. For example, when performing CAV (constant angular velocity) reproduction, the optical disk radial direction is divided into a plurality of linear velocity areas, the tap coefficients for each area are stored, and used when reproducing each area.

  1, 2, and 3, each circuit constituting the optical disk device is laid out on the same semiconductor chip, and performs tap coefficient holding and reload control while performing adaptive equalization processing.

  In all of the first to fourth embodiments, when the equalization target value selected by the target selection circuit 9 follows according to each PR output level of the FIR filter circuit 6, error convergence determination, By holding each equalization target value when the tap coefficient converges or at the end of reproduction, it is possible to speed up error convergence after resuming the adaptive equalization process. This can be realized by providing a holding circuit for each equalization target value, or by holding the previous value during the period from detection of DPLL lock release to lock detection, or during the period of occurrence of a control stop factor.

1 is a block diagram showing a first configuration of the present invention applied to an optical disc apparatus. The block diagram which shows the 2nd structure of this invention corresponding to reproduction | regeneration of DVD-RAM. The block diagram which shows the 3rd structure of this invention applied to the optical disk apparatus. The state transition diagram explaining the tap coefficient control in a 1st structure. Explanatory drawing of the control timing required by the block structure and 2nd structure of DVD-RAM. The state transition diagram explaining the tap coefficient control in a 3rd structure. The state transition diagram explaining the other tap coefficient control in a 3rd structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical head, 3 ... Preamplifier, 4 ... AD converter, 5 ... DPLL circuit, 6 ... FIR filter circuit, 7 ... Viterbi decoding circuit, 8 ... Data demodulation circuit, 9 ... Target selection circuit, 10 ... Error Arithmetic circuit 11 ... Convergence determining circuit 12 ... Coefficient holding circuit 13 ... Coefficient control circuit 14 ... UD part coefficient holding circuit 15 ... PID part coefficient holding circuit 17 ... First coefficient holding circuit 18 ... Second Coefficient holding circuit, 19 ... OR circuit, 20 ... system controller.

Claims (9)

An optical disc apparatus that accesses an optical disc on which data has been recorded by irradiating a laser beam from an optical head, performs adaptive equalization processing on a signal obtained from the optical disc, and obtains a reproduction signal,
Control means for controlling the start and stop of adaptive equalization processing;
FIR filter that performs adaptive equalization processing and can change tap coefficient values used for adaptive equalization processing;
Determining means for determining error convergence between the output of the FIR filter and the equalization target value;
Storage means for temporarily holding the tap coefficient value;
Tap coefficient value control means for controlling the tap coefficient value for the FIR filter,
The tap coefficient value control means includes
Start updating tap coefficient values for FIR filter after starting adaptive equalization processing,
In response to error convergence or stop control, control the holding of the tap coefficient value in the storage means,
An optical disc apparatus, wherein a tap coefficient value held in response to start control is output to the FIR filter, and adaptive equalization processing is performed using the tap coefficient value. An optical disk on which data comprising access units in the first area and the second area is recorded is accessed by irradiating a laser beam from the optical head, and the signal obtained from the optical disk is subjected to adaptive equalization processing and reproduced. An optical disk device for obtaining a signal,
Control means for controlling the start and stop of adaptive equalization processing;
FIR filter that performs adaptive equalization processing and can change tap coefficient values used for adaptive equalization processing;
First storage means for holding tap coefficient values for the first region;
Second storage means for holding tap coefficient values for the second region;
Identification means for performing first and second area identification on the reproduction signal from the optical disc;
Tap coefficient value control means for controlling the tap coefficient value for the FIR filter,
The tap coefficient value control means includes
Start updating tap coefficient values for FIR filter after starting adaptive equalization processing,
Based on the area identification by the identification unit, the first storage unit stores the first tap coefficient value, the second storage unit stores the second tap coefficient value,
Based on the area identification by the identification means, the first tap system value held in the first storage means is output to the FIR filter at the beginning of the first area, and adaptive equalization processing for the first area is performed. An optical disc apparatus characterized in that, at the beginning of the second area, the second tap system numerical value held in the second storage means is output to the FIR filter to perform adaptive equalization processing on the second area. An optical disc apparatus that accesses an optical disc on which data has been recorded by irradiating a laser beam from an optical head, performs adaptive equalization processing on a signal obtained from the optical disc, and obtains a reproduction signal,
Control means for controlling the start and stop of adaptive equalization processing;
FIR filter that performs adaptive equalization processing and can change tap coefficient values used for adaptive equalization processing;
First to Nth storage means (N is a positive integer) for temporarily holding the tap coefficient value;
Tap coefficient value control means for controlling the tap coefficient value for the FIR filter,
The tap type numerical control means includes:
Start updating tap coefficient values for FIR filter after starting adaptive equalization processing,
In response to the error convergence or stop control, control the sequential holding of the tap coefficient values in the first to Nth storage means,
The control means includes
In response to the start of adaptive equalization processing, the first to Nth tap coefficient values are selectively output to the FIR filter, and the adaptive equalization processing is resumed using the tap coefficient values. . A waveform equalization control method for accessing an optical disk on which data is recorded in block units composed of address information and recording data, and performing adaptive equalization processing on a signal obtained from the optical disk to obtain a reproduction signal,
In response to the start of the adaptive equalization process, the filter that performs the adaptive equalization process and starts updating the tap coefficient value of the FIR filter that can change the tap coefficient value used for the adaptive equalization process,
In response to the error convergence between the FIR filter output and the equalization target value, or the stop of the adaptive equalization process, the tap coefficient value is held,
In response to the start of adaptive equalization processing, a waveform equalization control method characterized by outputting a held tap coefficient value to the FIR filter and restarting adaptive equalization processing using the tap coefficient value. An optical disk on which data comprising access units in the first area and the second area is recorded is accessed by irradiating a laser beam from the optical head, and the signal obtained from the optical disk is subjected to adaptive equalization processing and reproduced. A waveform equalization control method for obtaining a signal,
In response to the start of the adaptive equalization process, the filter that performs the adaptive equalization process and starts updating the tap coefficient value of the FIR filter that can change the tap coefficient value used for the adaptive equalization process,
Based on the area identification, hold the first and second tap coefficient values,
Based on the area identification, the first tap system numerical value held at the head of the first area is output to the FIR filter to perform adaptive equalization processing on the first area, and the second value held at the head of the second area. A waveform equalization control method characterized in that an adaptive equalization process for the second region is performed by outputting the tap system numerical value to the FIR filter. A waveform equalization control method for an optical disc reproduction signal,
In response to the start of the adaptive equalization process, the filter that performs the adaptive equalization process and starts updating the tap coefficient value for the FIR filter that can change the tap coefficient value used for the adaptive equalization process,
Each time the error convergence between the FIR filter output and the equalization target value converges or the reproduction is stopped, the first to Nth (N is a positive integer) tap coefficient values are sequentially held,
A waveform equalization control method characterized in that, in the reproduction retry, the held first to Nth tap coefficient values are selectively output to the FIR filter, and the adaptive equalization processing is restarted using the tap coefficient values. A waveform equalization control method for an optical disc reproduction signal,
In response to the start of the adaptive equalization process, the filter that performs the adaptive equalization process and starts updating the tap coefficient value for the FIR filter that can change the tap coefficient value used for the adaptive equalization process,
The optical disk radial direction is divided into M areas (M is a positive integer) and held as a tap coefficient value of the area corresponding to the playback position in response to error convergence or playback stop,
A waveform equalization control method, comprising: outputting a tap coefficient value of a region corresponding to a reproduction position to the FIR filter at the time of reproduction, and restarting adaptive equalization processing using the tap coefficient value. A waveform equalization circuit that performs adaptive equalization processing on an optical disc reproduction signal,
Control means for controlling the start and stop of adaptive equalization processing;
FIR filter that performs adaptive equalization processing and can change the tap coefficient value used for adaptive equalization processing;
Determining means for determining error convergence between the FIR filter output and the equalization target value;
Storage means for temporarily holding the tap coefficient value;
A means for generating tap coefficient values for the FIR filter,
The generating means includes
Start updating tap coefficient values for FIR filters from the start of adaptive equalization processing,
In response to error convergence and stop control, control the holding of the tap coefficient value to the storage means,
A waveform equalization circuit which outputs a tap coefficient value held in response to start control to an FIR filter and performs adaptive equalization processing using the tap coefficient value. A waveform equalization circuit that performs adaptive equalization processing on a reproduction signal of an optical disc on which data constituting an access unit in a first area and a second area is recorded,
Control means for controlling the start and stop of adaptive equalization processing;
FIR filter that performs adaptive equalization processing and can change the tap coefficient value used for adaptive equalization processing;
First storage means for holding tap coefficient values for the first region;
Second storage means for holding tap coefficient values for the second region;
Identification means for performing first and second area identification on an optical disk reproduction signal;
A means for generating tap coefficient values for the FIR filter is provided.
The generating means includes
Start updating tap coefficient value for FIR filter from the start of adaptive equalization processing,
Based on the region identification by the identification unit, the tap coefficient value is held for the first and second storage units,
On the other hand, the first and second tap coefficient values held at the head of each area are output to the FIR filter based on the area identification, and adaptive equalization processing is performed on each area using the tap coefficient values. A characteristic waveform equalization circuit.

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