JP2009123275A - Data reproducing device and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data reproducing device capable of shortening time for making an error recovery. <P>SOLUTION: The data reproducing device sequentially executes a plurality of error recovery processing when a data reproducing error occurs, and determines reproducing easiness of a read signal read from a magnetic disk during execution of each error recovery process (S2), and determines the execution order of a plurality of error recovery processing to be subsequently executed based on the reproducing easiness determined for each error recovery process (S3). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a data reproduction apparatus and a control method thereof, and more particularly to a data reproduction apparatus and a control method thereof that sequentially execute a plurality of error recovery steps when a data reproduction error occurs.

  As a data reproducing apparatus, an apparatus using various types of media such as an optical disk and a magnetic tape is known. Among them, a magnetic disk apparatus is widely used as a storage device of a computer and is indispensable in a current computer system. It is one of the storage devices that cannot. Furthermore, not only computer systems, but also the use of magnetic disk devices such as moving image storage and playback devices, car navigation systems, and removable memories used in digital cameras, etc. have expanded due to their excellent characteristics. Yes.

  In a data reproducing device such as a magnetic disk device, when reproducing data recorded on a disk, a reproduction error may occur due to various factors such as head misalignment. When such a reproduction error occurs, the data reproduction device attempts to recover the reproduction error by executing an error recovery procedure (ERP) configured by a plurality of error recovery processes (see Patent Document 1). reference).

In each error recovery process, the reproduction operation is retried after changing the reproduction condition of the read signal so as to increase the possibility of data reproduction for each factor considered as a cause of the reproduction error. A specific change in the read signal reproduction condition is to change the value of the head offset amount by a certain amount.
International Publication No. WO00 / 17875 Pamphlet

  However, since ERP combines a plurality of error recovery processes and sequentially executes error recovery steps constituting the error recovery process, an error recovery process that cannot be expected to be effective for the cause of a reproduction error is included. Since there is a time for executing error recovery processing in which the effect of recovery of the reproduction error cannot be expected, there is a problem that it takes a long time to recover the reproduction error.

  In addition to errors that can identify factors such as Thermal Asperity (TA) errors and external impacts, there are errors that cannot identify error factors. Patent Document 1 discloses only an execution method of an error recovery procedure for a reproduction error whose factor can be specified, and does not disclose an execution procedure of an error recovery process for a reproduction error whose factor cannot be specified. Therefore, ERP for an error whose factor cannot be specified executes a plurality of error recovery processes in sequence, and therefore it is not possible to shorten the time required for recovery of a reproduction error.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a data reproducing apparatus and a control method thereof that can shorten the time required to recover a reproduction error. .

  In order to solve the above problems, the data reproduction device of the present invention is a data reproduction device that executes an error recovery procedure including a plurality of error recovery processes when a data reproduction error occurs, and the error recovery process includes: A calculation unit that includes one or more error recovery steps having different reproduction conditions, and that calculates an index value representing a reproduction level of a read signal read from a recording medium for each error recovery step; and an index value representing the reproduction level And determining a second execution order of the error recovery steps to be executed again after the error recovery steps are executed and cannot be reproduced in accordance with the first execution order.

  In the aspect of the invention, the determination unit may repeatedly execute the error recovery step of the top one or more of the index values indicating the reproduction level a plurality of times, and then execute another error recovery step. Determine the second execution order.

  In one aspect of the present invention, the calculation unit does not calculate an index value indicating the reproduction level for a recovery step belonging to a specific error recovery process among the plurality of error recovery processes, and the determination unit A recovery step belonging to the specific error recovery process is included in a predetermined position in the second execution order.

  In this aspect, the specific error recovery process is an error recovery process for a reproduction error due to a lack of at least a part of the read signal.

  In the aspect of the invention, the determining unit may execute the second execution order so as to execute a plurality of error recovery steps higher in the index value indicating the reproduction level and not execute other error recovery steps. decide.

  In the aspect of the invention, the calculation unit normalizes an index value indicating the reproduction level according to a time when the read signal is read.

  In one aspect of the present invention, the calculation unit includes a maximum likelihood decoder that decodes a likely data sequence from the read signal, and the maximum likelihood decoder includes each piece of data that is a candidate for the likely data sequence. A column metric is obtained, and an index value representing the reproduction level is calculated based on the metric of each data column.

  In one aspect of the present invention, the calculation unit includes a maximum likelihood decoder that decodes a likely data sequence from the read signal, and performs the reproduction based on an error between the read signal and the likely data sequence. The value of the index indicating the level is calculated.

  In the aspect of the invention, the determination unit may be a new combination of two or more error recovery steps belonging to different error recovery processes among the plurality of error recovery steps based on an index value representing the reproduction level. An error recovery step is created and included in the second execution order.

  Next, a control method for a data reproduction apparatus according to the present invention is a control method for a data reproduction apparatus that executes an error recovery procedure including a plurality of error recovery processes when a data reproduction error occurs, the error recovery process Includes one or more error recovery steps with different playback conditions, and when a data playback error occurs, the error recovery step is executed according to the first execution order and executed according to the first execution order. Calculating an index value representing the reproduction level of the read signal read from the recording medium for each error recovery step, and performing the error recovery step according to a first execution order based on the index value representing the reproduction level. , And a second execution order of the plurality of error recovery steps to be executed again after being unable to be reproduced is determined.

  In the aspect of the invention, the second execution order may be executed by repeatedly performing error recovery processing of the top one or more of the index values indicating the reproduction level a plurality of times, and thereafter executing other error recovery processing. Decided to do.

  In one aspect of the present invention, a recovery step belonging to a specific error recovery process among the plurality of error recovery processes does not calculate an index value indicating the reproduction level, and belongs to the specific error recovery process. The step is included in a predetermined position in the second execution order.

  In this aspect, the specific error recovery process is an error recovery process for a reproduction error due to a lack of at least a part of the read signal.

  In the aspect of the invention, the second execution order is determined so as to execute a plurality of error recovery steps higher than the index value indicating the reproduction level and not to execute other error recovery steps.

  In one embodiment of the present invention, an index value indicating the reproduction level is normalized according to a time when the read signal is read.

  In one aspect of the present invention, a maximum likelihood decoder that decodes a likely data sequence from the read signal obtains a metric for each data sequence that is a candidate for the likely data sequence, and the metric for each data sequence is obtained. Based on this, an index value representing the reproduction level is calculated.

  In one aspect of the present invention, a maximum likelihood decoder that decodes a likely data sequence from the read signal uses an index value representing the reproduction level based on an error between the read signal and the likely data sequence. Is calculated.

  In one aspect of the present invention, based on the weighting, a new error recovery process is created by combining two or more error recovery steps belonging to different error recovery processes among the plurality of error recovery steps, and the second Include in the execution order.

  According to the present invention, the error recovery process is composed of one or more error recovery steps with different playback conditions, and based on the value of the index representing the playback level of the read signal read from the disc determined at each error recovery step, The error recovery step is executed in accordance with the first execution order and the second execution order of the error recovery step executed again after being unable to be reproduced is determined. The recovery step can be preferentially executed. As a result, it is possible to shorten the time until the reproduction error is recovered.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a configuration example of a data reproducing apparatus 1 according to an embodiment of the present invention. The data reproducing device 1 is a magnetic disk device, and houses a magnetic disk 2, a spindle motor 3, a magnetic head 4, a suspension arm 5, a carriage 6, a voice coil motor 7, and a head amplifier 14 in a housing 9. The data reproducing apparatus 1 has a main control circuit 10, a read / write channel (R / W channel) 13, and a motor driver 17 on a substrate outside the housing 9.

  The magnetic disk 2 is rotationally driven by a spindle motor 3. A plurality of tracks 21 arranged concentrically are formed on the magnetic disk 2. Each track 21 is formed with a servo data area 21 s arranged at a predetermined cycle along the circumferential direction, and a user data area 21 u positioned between the servo data areas. Servo data composed of address data, burst signals, and the like is recorded in the servo data area 21s. In addition, user data is recorded in the user data area 21u.

  The magnetic head 4 is attached to the tip of the suspension arm 5 and supported on the magnetic disk 2 when unloaded. The suspension arm 5 has a proximal end attached to a carriage 6 pivotally supported by a housing 9. The voice coil motor 7 rotates the carriage 6 to move the magnetic head 4 on the magnetic disk 2 in a substantially radial direction.

  The main control circuit 10 includes a microprocessing unit (MPU) and a memory such as a ROM or a RAM. The main control circuit 10 implements various controls such as position control of the magnetic head 4 and data recording / reproduction control by reading and executing a program recorded in the magnetic disk 2 or memory. In the present embodiment, the main control circuit 10 functions as a determination unit. These functions will be described in detail later.

  In the position control of the magnetic head 4, the main control circuit 10 specifies the current position of the magnetic head 4 based on the servo data input from the R / W channel 13 and positions the magnetic head 4 on the target track. Is output to the motor driver 17. The motor driver 17 converts the control signal to analog, amplifies it, and outputs it to the voice coil motor 7. Further, the main control circuit 10 includes a hard disk controller (HDC) and a buffer memory. The HDC has an interface controller, an error correction circuit, a buffer controller, and the like.

  When the main control circuit 10 receives user data to be recorded on the magnetic disk 2 from an external host, the main control circuit 10 adds an error correction code (ECC) to the user data and outputs the user data to the R / W channel 13. When user data is input from the main control circuit 10, the R / W channel 13 modulates the user data and outputs it to the head amplifier 14. When the modulated user data is input from the R / W channel 13, the head amplifier 14 converts the user data into a write signal and outputs it to the magnetic head 4. The magnetic head 4 includes a recording element. When a write signal is input from the head amplifier 14, the magnetic head 4 applies a recording magnetic field corresponding to the write signal to the magnetic disk 2. As a result, magnetization representing user data is recorded on the magnetic disk 2.

  The magnetic head 4 includes a reproducing element, reads a magnetic field leaking from the magnetization recorded on the magnetic disk 2 as a read signal, and outputs the read signal to the head amplifier 14. This reproducing element is composed of a magnetoresistive element (MR element), a GMP element, a TMR element, a CPP-GMR element, and the like. When the read signal read from the magnetic disk 2 is input from the magnetic head 4, the head amplifier 14 amplifies the read signal and outputs it to the R / W channel 13. When the amplified read signal is input from the head amplifier 14, the R / W channel 13 converts the read signal into digital data, demodulates it, and outputs it to the main control circuit 10. The R / W channel 13 extracts servo data from the read signal at a predetermined sampling period and outputs the servo data to the main control circuit 10. A detailed configuration example of the lead system of the R / W channel 13 will be described in detail later.

  When the demodulated user data is input from the R / W channel 13, the main control circuit 10 analyzes the ECC added to the user data, corrects the error as necessary, and then externalizes the user data. Send to host. Here, the main control circuit 10 determines the occurrence of a reproduction error when error correction of user data by ECC has failed. That is, the occurrence of a reproduction error is detected when the original user data is not decoded from the read signal read from the magnetic disk 2.

  FIG. 2 shows a configuration example of the read system of the R / W channel 13. The R / W channel 13 includes a variable gain amplifier 31, an asymmetry correction circuit 32, a waveform equalization circuit 33, an A / D converter 34, an FIR filter 35, a Viterbi decoder 36, and a demodulation circuit 37 as a lead system configuration. .

  When the read signal amplified from the head amplifier 14 is input, the variable gain amplifier 31 makes the amplitude of the waveform of the read signal constant. When a read signal with a constant amplitude is input from the variable gain amplifier 31, the asymmetry correction circuit 32 corrects the vertical asymmetry of the waveform. The waveform equalization circuit 33 is a CTF (Continuous Time Filter). When a read signal whose waveform asymmetry is corrected is input from the asymmetry correction circuit 32, noise is removed and waveform equalization is performed. When the waveform equalized read signal is input from the waveform equalizing circuit 33, the D converter 34 converts the read signal from analog to digital. When a read signal is input from the A / D converter 34, a FIR (Finite Impulse Response) filter 35 equalizes the read signal again in accordance with the partial response method (PR method).

  The Viterbi decoder 36 is an example of a maximum likelihood decoder, and Viterbi decodes a likely data sequence from the read signal by a Viterbi algorithm. This data string is demodulated by the demodulation circuit 37 and output to the main control circuit 10. The read signal input to the Viterbi decoder 36 ideally takes one of three values (-1, 0, 1), but in reality, it is often an intermediate value between them. For this reason, in Viterbi decoding, maximum likelihood detection is made as to which of the three values (−1, 0, 1) each value of the read signal corresponds to.

  Specifically, the Viterbi decoder 36 calculates metrics for each transition path in the process of narrowing down likely transition paths from among a plurality of candidate transition paths. The metric is a value obtained by accumulating the square of the error between the value of the read signal and the value of the transition path. The smaller this value, the more likely the transition path is determined.

  Here, the Viterbi decoder 36 has a function of obtaining a difference between a likely transition path metric and another transition path metric. This difference is called the Viterbi Metrics Margin (VVM). VVM is one of the indexes representing the read signal reproduction level. That is, the larger the VVM, the easier it is to narrow down the likely transition paths, and it is easier to reproduce the data string from the read signal. On the other hand, the smaller the VVM, the more difficult it is to narrow down the likely transition paths, and thus it is difficult to reproduce the data string from the read signal.

  The Viterbi decoder 36 has a function of obtaining an equivalent error (MSE: Mean Square Error) obtained by squaring and averaging the error between the value of the read signal and the value of the likely data string that has been Viterbi decoded. ing. MSE is one of the indexes representing the read signal reproduction level. That is, the smaller the MSE, the more likely the Viterbi-decoded plausible data sequence is correct, and the easier it is to reproduce the data sequence from the read signal. On the other hand, the larger the MSE, the less likely the Viterbi-decoded plausible data sequence is correct, so it is more difficult to reproduce the data sequence from the read signal.

  The R / W channel 13 described above has a “measurement mode” in which the Viterbi decoder 36 measures MSE and VMM and outputs them to the main control circuit 10. This measurement mode is usually a mode used in an inspection process during manufacturing.

In the present embodiment, the main control circuit 10 performs an error recovery procedure (ERP: Error described later).
When executing “Recovery Procedure”, the “measurement mode” is set in the R / W channel 13 and at least one of the MSE and the VMM is acquired from the R / W channel 13. In this embodiment, the MSE is acquired.

  When the main control circuit 10 acquires user data from the R / W channel 13, as shown in FIG. 9, the main control circuit 10 adjusts the R / W according to the period in which the user data portion appears in the read signal read from the magnetic disk 2. Assert the read gate of channel 13. At this time, the R / W channel 13 set to the measurement mode calculates the MSE and VMM according to the period during which the read gate is asserted. (Function as a calculator)

  Here, the measured MSE and VMM are values integrated during the period in which the measurement window is open. As shown in FIG. 9B, when user data is divided by servo data, or when the measurement time cannot be controlled to be constant and there is an error, the period for integrating the MSE and VMM is set for each error recovery procedure. Different. Therefore, the main control circuit 10 can also normalize the acquired value according to the period (number of bits) during which the measurement window is open. By standardizing, even when there is a difference in measurement time (lamination time), it is preferable because the value of the index representing the reproduction level can be compared with high accuracy.

  Hereinafter, an operation example of the main control circuit 10 will be described. The main control circuit 10 starts an error recovery procedure (ERP) shown in the flowchart of FIG. 3 when error correction of user data by ECC fails and a reproduction error occurs. The ERP is configured by a plurality of error recovery processes, and the plurality of error recovery processes is configured by one or more error recovery steps in which reproduction conditions are changed. Here, the error recovery process is a process corresponding to each factor that can be considered as a cause of the reproduction error. In the error recovery step, the reproduction condition of the read signal is changed so as to suppress each factor.

  In S <b> 1, the main control circuit 10 sets the “measurement mode” in the R / W channel 13.

  In S2, the main control circuit 10 reads an initial table in which the first execution order is described. Then, the error recovery steps are sequentially executed according to the first execution order. The initial table and the program describing the execution contents of each error recovery step are recorded in the memory in the main control circuit 10 or the magnetic disk 2.

  In S2, the main control circuit 10 ends the error recovery procedure (EPR) without proceeding to the next error recovery step when the reproduction error is recovered by executing the error recovery process.

  FIG. 5 shows an example of the contents of the initial table. In this initial table, the execution order of error recovery steps constituting error recovery processing is described. The error recovery processing includes types of off-track write recovery processing, MR asymmetric recovery processing, resolution recovery processing, and disk defect error recovery processing.

  The off-track write recovery procedure is an error recovery process for a reproduction error caused by user data being recorded out of the center of the track. In this off-track write recovery process, the offset amount of the magnetic head 4 is changed and the reproduction operation is retried.

  The MR asymmetry recovery procedure is an error recovery process for a reproduction error caused by the fact that the waveform of the read signal read by the magnetoresistive effect element is vertically asymmetric. In this MR asymmetry recovery process, the parameters of the asymmetry correction circuit 32 included in the R / W channel 13 are changed, and the reproduction operation is retried.

  The resolution recovery process is an error recovery process for a reproduction error caused by a lack of resolution of the read signal that has been read. In this resolution recovery processing, the parameters of the waveform equalization circuit 33 included in the R / W channel 13 are changed, and the reproduction operation is retried.

  The disk defect error recovery process is an error recovery process for a reproduction error caused by a part of the read signal being lost due to a partial defect of the magnetic disk 2. In this disk defect error recovery process, the reproduction operation is retried and error correction is performed by ECC by limiting the missing portion of the read signal.

  In S2 shown in FIG. 3, the main control circuit 10 acquires the MSE measured in the Viterbi decoder 36 from the R / W channel 13 while each error recovery step is being executed. The weight of each error recovery process is determined according to the MSE.

  In the determination of weighting, the acquired MSE value may be used as a weighting value as it is, or a threshold value may be provided to determine the presence or absence of weighting. Further, a plurality of threshold levels may be provided to classify the size of the MSE.

  As described above, the MSE measured by the Viterbi decoder 36 is one of the indexes representing the read signal reproduction level. Therefore, the weighting determined according to the MSE of the read signal obtained when each error recovery step is executed corresponds to the read signal reproduction level when each error recovery process is executed.

  The determined weight of each error recovery step is stored in a weighting table created in a memory or the like. FIG. 6 shows an example of the contents of the weighting table. In S2, the main control circuit 10 determines the weight of each recovery step according to the MSE acquired from the R / W channel 13 when executing each recovery step, and stores it in the weighting table. In this weighting table, the weight of each error recovery step is stored, and the priority of each recovery step is determined according to the weight.

  Of these error recovery processes, no weight is determined for the disk defect error recovery process. This is because the disk defect error recovery process is not a process of changing the read signal generation condition, and therefore the MSE of the read signal obtained when the disk defect error recovery process is executed hardly changes.

  Next, in S3 shown in FIG. 3, the main control circuit 10 can reproduce even if the error recovery steps are executed according to the first execution order based on the weights of the error recovery steps stored in the weighting table. The second execution order of the error recovery step that is executed again after the absence is determined (function as a determination unit).

  Then, the main control circuit 10 records a correction table describing the determined second execution order in a memory or the like. FIG. 7 shows an example of the contents of the correction table. In this correction table, the execution order is determined so that an error recovery step having a high weight (that is, a high priority) is preferentially executed in the weighting table. By preferentially executing error recovery steps with high priority in the second execution order, there is a high possibility that error recovery can be performed first, and there is an increased possibility that the time required for error recovery can be shortened. .

  In the correction table shown in FIG. 7, the execution order is determined so that a plurality of error recovery steps (which may be one error recovery process) with high weighting in the weighting table are repeated a predetermined number of times. In the second execution order, high-priority error recovery processing can be preferentially executed multiple times, so there is a higher possibility of error recovery first, and the time required for error recovery may be shortened Will increase.

  In the correction table shown in FIG. 7, the execution order is determined so that the error recovery step of the disk defect error recovery process for which weighting has not been determined is executed last. Further, the present invention is not limited to this, and it may be incorporated into a plurality of highly weighted error recovery steps that are repeated a predetermined number of times, or may be executed after repeating a plurality of highly weighted error recovery steps a number of times. Furthermore, the processing may be performed before or after the error recovery step of the disk defect error recovery processing according to the weighting of other error recovery steps. A more appropriate execution order is determined by determining the error recovery step of the error recovery process, in which the weighting is not easily reflected in the ease of playback, separately from the execution order determined based on the ease of playback. be able to.

  Further, the correction table is not limited to the table shown in FIG. 7, and it may be determined that only a plurality of error recovery steps having a higher weight are executed and other error recovery steps are not executed. By not executing the error recovery step with a low weight, it is possible to move to the next execution order earlier.

  Next, in S4 shown in FIG. 3, the main control circuit 10 reads the correction table and sequentially executes error recovery steps according to the second execution order described in the correction table. Also in S4, the main control circuit 10 determines the weight according to the MSE of the read signal obtained at the time of executing each error recovery process, and stores it in the weighting table. Also in S4, when the reproduction error is recovered by executing the error recovery process, the main control circuit 10 ends the error recovery procedure (EPR) without proceeding to the next error recovery process.

  FIG. 4 shows a specific operation example of the main control circuit 10 when the correction table is used. The main control circuit 10 repeats the sequential execution of the error recovery steps of priorities 1 to 5 and the saving of the weights N times (S41). Next, error recovery processing of priority 6 and later is sequentially executed and weights are stored (S43), and thereafter error recovery processing in which weighting is not determined is executed (S44).

  As described above, by weighting each error recovery step according to the MSE representing the readability of the read signal, and sequentially executing a plurality of error recovery steps according to the execution order determined based on these weightings, An appropriate error recovery step can be preferentially performed for the cause of the reproduction error, and the time until the reproduction error is recovered can be shortened.

  If the reproduction error is not recovered in S4, the process returns to S3, and the execution order of the error recovery steps to be executed next is determined based on the weight of each error recovery step stored in the weighting table in S4. Then, the error recovery steps are sequentially executed according to the determined execution order (S4). These operations are repeated until the reproduction error is recovered or until a predetermined time elapses.

  Hereinafter, modified examples of the correction table and modified examples of the operation of the main control circuit 10 based on these tables will be described.

  FIG. 8 shows a modification of the correction table. In S3, the main control circuit 10 determines the execution order for each error recovery step based on the weighting of each error recovery step stored in the weighting table shown in FIG. 6, and stores it in the correction table. In particular, in this correction table, a new error recovery step is created by combining error recovery steps constituting a plurality of different error recovery processes with high weights in the weighting table shown in FIG. 6, and this new error recovery step has priority. The execution order is determined so as to be executed automatically. In S4, the main control circuit 10 sequentially executes each recovery step according to the execution order described in the correction table.

  This new error recovery step is a step of retrying the reproduction operation after changing all the read signal generation conditions to be changed in each of a plurality of error recovery processes with high weighting. Here, error recovery steps of different types of error recovery processing are combined. Specifically, the new error recovery process is a process in which a plurality of recovery steps having high weights are combined in the weighting table shown in FIG. 6, and the parameter applied in each of the plurality of recovery steps having high weights. Combine the changes and retry the playback operation. In this way, by combining the recovery steps of the error recovery processes with high weights and different from each other, the possibility of reproduction can be increased even when a reproduction error occurs due to a combination of a plurality of error factors. Also, by preferentially executing a new error recovery process that combines a plurality of error recovery processes with high weights, the time until the reproduction error is recovered can be further shortened.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the format of the said embodiment. For example, the correction table may be stored, and when the next reproduction error occurs, each error recovery process may be sequentially executed using the stored correction table instead of the initial table.

It is a block diagram showing the example of a structure of the data reproduction apparatus which concerns on one Embodiment of this invention. It is a block diagram showing the structural example of the read type | system | group of R / W channel. It is a flowchart showing the operation example of a data reproduction apparatus. It is a flowchart showing the specific operation example of S4 in FIG. It is a figure showing the example of the content of an initial table. It is a figure showing the example of the content of a weighting table. It is a figure showing the example of the content of a correction table. It is a figure showing the modification of a correction table. It is explanatory drawing of a measurement window.

Explanation of symbols

  1 data reproducing device, 2 magnetic disk, 3 spindle motor, 4 magnetic head, 5 suspension arm, 6 carriage, 7 voice coil motor, 9 housing, 10 main control circuit, 13 R / W channel, 14 head amplifier, 17 motor Driver, 21 tracks, 21s Servo data area, 21u User data area, 31 Variable gain amplifier, 32 Asymmetry correction circuit, 33 Waveform equalization circuit, 34 A / D converter, 35 FIR filter, 36 Viterbi decoder, 37 Demodulation circuit .

Claims (18)

A data reproduction apparatus that executes an error recovery procedure including a plurality of error recovery processes when a data reproduction error occurs,
The error recovery process includes one or more error recovery steps having different reproduction conditions,
A calculation unit that calculates a value of an index representing a reproduction level of a read signal read from a recording medium for each error recovery step;
The error recovery step is executed again after determining the weight of each recovery step based on the value of the index representing the playback level, and executing the error recovery step according to a first execution order by the weighting and failing to reproduce. A determination unit for determining a second execution order of
A data reproducing apparatus comprising: The determination unit repeatedly executes the error recovery step of the top one or more of the weights a plurality of times, and then determines the second execution order to execute another error recovery step.
The data reproducing apparatus according to claim 1. The calculation unit does not calculate an index value indicating the reproduction level for a recovery step belonging to a specific error recovery process among the plurality of error recovery processes,
The determination unit includes a recovery step belonging to the specific error recovery process in a predetermined position of the second execution order;
The data reproducing apparatus according to claim 2. The specific error recovery process is an error recovery process for a reproduction error due to a lack of at least a part of the read signal.
The data reproducing apparatus according to claim 3. The determination unit executes the plurality of error recovery steps of the top weighting and determines the second execution order so as not to execute other error recovery steps.
The data reproducing apparatus according to claim 1. The calculation unit normalizes an index value indicating the reproduction level according to a time when the read signal is read.
The data reproducing apparatus according to claim 1. The calculation unit includes a maximum likelihood decoder that decodes a likely data sequence from the read signal,
The maximum likelihood decoder obtains metrics of each data sequence that is a candidate for the likely data sequence,
Based on the metrics of each data string, a value of an index representing the reproduction level is calculated.
The data reproducing apparatus according to claim 1. The calculation unit includes a maximum likelihood decoder that decodes a likely data sequence from the read signal,
Based on an error between the read signal and the likely data string, an index value representing the reproduction level is calculated.
The data reproducing apparatus according to claim 1. The determination unit creates a new error recovery step by combining two or more error recovery steps belonging to different error recovery processes among the plurality of error recovery steps based on the weighting, and sets the second execution order in the second execution order. include,
The data reproducing apparatus according to claim 1. A data reproducing apparatus control method for executing an error recovery procedure including a plurality of error recovery processes when a data reproduction error occurs,
The error recovery process includes one or more error recovery steps having different reproduction conditions,
When a data reproduction error occurs, the error recovery step is executed according to a first execution order,
Calculating an index value representing a reproduction level of a read signal read from a recording medium for each error recovery step executed according to the first execution order;
Determining the weight of each recovery step based on the value of the index representing the playback level;
Determining a second execution order of the plurality of error recovery steps to be executed again after the error recovery steps are executed according to a first execution order by the weighting and cannot be reproduced;
A method for controlling a data reproducing apparatus. The second execution order is determined to repeatedly execute the error recovery process of the top one or more of the weights a plurality of times, and then execute another error recovery process.
The method for controlling the data reproducing apparatus according to claim 10. For a recovery step belonging to a specific error recovery process among the plurality of error recovery processes, an index value representing the reproduction level is not calculated,
Including a recovery step belonging to the specific error recovery process at a predetermined position in the second execution order;
The method for controlling the data reproducing apparatus according to claim 11. The specific error recovery process is an error recovery process for a reproduction error due to a lack of at least a part of the read signal.
The method for controlling the data reproducing apparatus according to claim 12. The second execution order is determined so as to execute the plurality of error recovery steps of the weighting and not to execute other error recovery steps.
The method for controlling the data reproducing apparatus according to claim 10. Normalizing the value of the index representing the reproduction level according to the time of reading the read signal;
The method for controlling the data reproducing apparatus according to claim 10. An index representing the reproduction level based on the metrics of each data string obtained by obtaining a metric of each data string that is a candidate for the likely data string by a maximum likelihood decoder that decodes the likely data string from the read signal Calculate the value of
The method for controlling the data reproducing apparatus according to claim 10. A maximum likelihood decoder that decodes a likely data sequence from the read signal calculates an index value representing the reproduction level based on an error between the read signal and the likely data sequence.
The method for controlling the data reproducing apparatus according to claim 10. Based on the weighting, a new error recovery process is created by combining two or more error recovery steps belonging to different error recovery processes among the plurality of error recovery steps, and is included in the second execution order.
The method for controlling the data reproducing apparatus according to claim 10.

Images