JP2006318531A - Data reproducing apparatus and method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep stably a whole data reproducing apparatus without depending on difference of various setting conditions about the data reproducing apparatus. <P>SOLUTION: A PLL part 31 converts non-synchronous sampling data supplied from an AGC/DCC part 4 to synchronous sampling data conforming to algorithm corresponding to PR(1, -1) or PR(1, 0, -1). A PRML part 33 detects a channel bit column corresponding to a RLL recording code from the synchronous sampling data conforming to algorithm corresponding to PR(1, -1) or PR(1, 0, -1) and offers for sync sensing/decoding part 34. A switching discrimination control part 32, for example, discriminates switching of algorithm utilized by the RLL part 31 and the PRML part 33 based on information from the PLL part 31, and provides the discriminated result tothe PLL part 31 and the PRML part 33 as switching discrimination information chg. This invention can be applied to a data reproducing apparatus mounted with the PLL. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data reproduction apparatus and method, and a program, and in particular, a phase that can keep the entire data reproduction apparatus including the phase synchronization apparatus stable regardless of various setting conditions for the data reproduction apparatus. The present invention relates to a synchronization device and method, a data reproduction device and method, and a program.

In recent years, a digital PLL (Phase Locked Loop) that has appeared as one of phase synchronization devices (see, for example, Patent Documents 1 to 6 and Non-Patent Document 1) converts asynchronous sampling data corresponding to RLL codes into synchronous sampling data. In this case, feedback control can be performed based on the phase error (phase_error) so as to output synchronous sampling data shaped into a predetermined partial response system equalization.
JP 2001-358882 A Japanese Patent No. 3071142 Japanese Patent Laid-Open No. 10-69727 Japanese National Patent Publication No. 10-508135 JP 2000-76805 A JP 2002-42428 A Interpolated Timing Recovery For Hard Disk Drive Read Channels Mark Spurbeck and Richard T. Behrens / Cirrus Logic 1997 IEEE p1618-1624

  However, in a data reproduction device (system) that reproduces the original data (RLL encoded original data) from the synchronous sampling data output from such a PLL, depending on various setting conditions for the data reproduction device, There is a problem that the entire system may become unstable, such as the error rate of the received data suddenly becoming impossible.

  The present invention has been made in view of such a situation, and can maintain the entire data reproducing apparatus (system) including the phase synchronization apparatus stably regardless of the difference in various setting conditions for the data reproducing apparatus. It can be done.

  When data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the data reproducing apparatus of the present invention is in accordance with the first algorithm or the second algorithm. In accordance with the phase synchronization means for generating synchronous data synchronized with a predetermined frequency from the asynchronous data, and the third algorithm corresponding to the first algorithm or the fourth algorithm corresponding to the second algorithm , Data detection means for detecting a channel bit string corresponding to the RLL recording code from synchronization data generated by the phase synchronization means, decoding means for decoding the channel bit string detected by the data detection means, phase synchronization means, and data detection Data generated, detected or utilized by at least one of the means and the decoding means. A first switching between the first algorithm and the second algorithm, and a second between the third algorithm and the fourth algorithm, based on a data string that is a sequence and does not have identification information individually. It is characterized by comprising switching determination means for determining whether to switch.

  The switching determination unit can determine the first switching and the second switching based on the data string used by the phase synchronization unit.

  The phase synchronization means uses two or more sampling values in a predetermined section of the synchronization data and two or more provisional determination values for each of the two or more sampling values in the predetermined section, Phase error information detection means for detecting phase error information indicating a phase error, and the switching determination means is based on two or more provisional determination values used by the phase error information detection means of the phase synchronization means. The determination of switching and second switching can be performed.

  The first algorithm and the third algorithm are algorithms corresponding to the first partial response method, and the second algorithm and the fourth algorithm are algorithms corresponding to the second partial response method, and the switching determination is performed. The means includes a transition pattern of two or more provisional judgment values including at least two or more provisional judgment values used by the phase error information detection means, in a partial response method corresponding to an algorithm currently used. In the case of determining whether or not it is a specific pattern that can not exist, if it is determined that it is a specific pattern, it is determined that the first switching and the second switching are performed, and if it is determined that it is not a specific pattern, It can be determined that the first switching and the second switching are prohibited.

  The phase error information detection means sets the sampling value to be processed in the synchronization data as data_now, sets the sampling value immediately before the data_now as data_D, sets the temporary determination value for data_now as slice_now, and sets the temporary determination value for data_D as slice_D. As the phase error information, phase error information is detected according to the first calculation method using the calculation formula represented by phase_err = (data_now * slice_D) − (data_D * slice_now), and the first partial response method is used. And the second partial response scheme can have a relationship in which phase_err of at least one of the schemes is 0 for all combinations of slice_D and slice_now.

  The phase error information detection means detects the phase error information according to the first calculation method when the switching determination means determines that the pattern is not a specific pattern, and further, when the switching determination means determines that the pattern is a specific pattern, The phase error information can be detected according to the second calculation method.

  The second calculation method may be a calculation method that outputs 0 as phase error information.

  The specific pattern refers to a phase position between a predetermined first value and a second value adjacent to the first value of two or more sampling values used by the phase error information detection means. It can be made to be a pattern generated in the back phase state that is the phase position when only one of the two values exceeds a predetermined threshold value.

  Between the first partial response method and the second partial response method, the phase position of the first value and the second value is the position in the ideal state for either one of the methods. In some cases, there may be a relationship that the position of the back phase state is obtained for the other method.

  D = 1 of the RLL recording code recorded in the recording medium, the first partial response method is PR (1, -1), and the second partial response method is PR (1,0, -1). Can be.

  The sampling value to be processed in the synchronous data is set as data_now, the sampling value immediately before that data_now is set as data_D, the temporary determination value for data_now is set as slice_now, and the temporary determination value for data_D is set as slice_D. It can be determined whether the pattern of the combination of slice_D and slice_now is a specific pattern in PR (1, -1) or PR (1,0, -1) currently used.

  The sampling value immediately before data_now is set to data_2D, the provisional determination value for data_2D is set to slice_2D, and the switching determination unit further uses a combination pattern of slice_2D, slice_D, and slice_now that currently uses PR (1, -1 ) Or PR (1,0, -1).

  The switching determination means can further generate switching determination information indicating the determination result.

  The phase synchronization means includes first phase error information detection means for detecting phase error information indicating a phase error of the synchronization data according to the first algorithm, and second phase for detecting phase error information according to the second algorithm. And when the switching determination information generated by the switching determination unit includes information indicating that the first switching is performed, the first phase error information detection unit and the second phase error information detection unit , When the switching determination information generated by the switching determination unit includes information that the first switching is not performed, the first phase error information detection unit Switching from the currently used one of the second phase error information detecting means and the second phase error information detecting means can be prohibited.

  Each of the first phase error information detection means and the second phase error information detection means includes two or more sampling values in a predetermined section of the synchronization data and two or more sampling values in the predetermined section. Phase error information is detected using two or more provisional determination values for each, and the phase synchronization means further includes a first provisional determination value calculation means for calculating a provisional determination value according to the first algorithm, A second temporary determination value calculating means for calculating a temporary determination value according to the second algorithm, wherein the switching determination information generated by the switching determination means includes information indicating that the first switching is performed; The switching determination information generated by the switching determination unit is switched from the currently used one of the first temporary determination value calculation unit and the second temporary determination value calculation unit to the other. Do not switch In the case where the information is included, switching from one of the first provisional determination value calculation means and the second provisional determination value calculation means currently used to the other is prohibited. it can.

  When the switching determination information generated by the switching determination unit includes information that the first switching is performed, the predetermined setting value for the phase synchronization unit is further changed, and the switching determination information generated by the switching determination unit is When information indicating that the first switching is not performed is included, it is possible to prohibit a change in a predetermined set value for the phase synchronization means.

  The data detection means has first data detection means for detecting a channel bit string from the synchronization data according to the third algorithm, and second data detection means for detecting a channel bit string from the synchronization data according to the fourth algorithm. When the switching determination information generated by the switching determination unit includes information that the second switching is performed, one of the first data detection unit and the second data detection unit that is currently used When the switching determination information generated by the switching determination unit includes information that the second switching is not performed, the current data of the first data detection unit and the second data detection unit Switching from one used to the other can be prohibited.

  The data reproducing apparatus further includes waveform shaping means for shaping the asynchronous data generated by the sampling means to a predetermined waveform and outputting the shaped asynchronous data, and the phase synchronization means is the asynchronous data output from the waveform shaping means. If the switching determination information generated by the switching determination unit includes information that at least one of the first switching and the second switching is performed, a predetermined setting for the waveform shaping unit is generated. When the value is changed and the switching determination information generated by the switching determination unit includes information indicating that neither the first switching nor the second switching is performed, the change of the predetermined setting value for the waveform shaping unit is prohibited. You can make it.

  The data playback device further performs gain control (AGC: Auto Gain Control) and DC (Direct Current) offset cancellation (DCC: DC Cancel) of asynchronous data output from the waveform shaping means, and the asynchronous data after AGC and DCC is processed. AGC / DCC means for outputting is provided, the phase synchronization means generates synchronous data from the asynchronous data output from the AGC / DCC means, and the switching determination information generated by the switching determination means includes the first switching and the first switching. In the case of including information indicating that at least one of the two switching operations is performed, a predetermined setting value for the AGC / DCC unit is further changed, and the switching determination information generated by the switching determination unit includes the first switching and the first switching. In the case of including information that the switching of 2 is not performed together, it is possible to prohibit the change of a predetermined set value for the AGC / DCC means.

  The switching determination information is a flag. When the flag is set, it indicates that the first switching and the second switching are performed. When the flag is set, both the first switching and the second switching are performed. It can be shown not to do.

  The flag can be weighted based on a predetermined condition so that a flag is raised when a data string that does not have identification information individually satisfies a predetermined condition.

  The predetermined condition may be a condition that a pattern string that cannot ideally appear in a data string that does not have identification information individually includes a predetermined amount or more.

  The data reproducing device further generates a differential response signal of the analog signal when the data recorded in the predetermined recording medium as the RLL recording code of d> 0 is read from the predetermined recording medium as an analog signal. A differential means and a sampling means for generating asynchronous data by asynchronously sampling an analog differential response signal generated by the differential means at a predetermined frequency, and the phase synchronization means are generated by the sampling means. Synchronous data can be generated from asynchronous data.

  The phase synchronization means includes, in accordance with the first algorithm or the second algorithm, phase error information detection means for detecting phase error information indicating a phase error of the synchronization data, and at least phase error information detected by the phase error information detection means. A loop filter unit that performs a loop filter operation and outputs a result of the calculation, and performs a predetermined accumulation process on the operation result output from the loop filter unit, and configures asynchronous data based on the processing result. The remainder accumulating means that generates and outputs information necessary for adjusting the phase position of each sampling value, and the phase of each sampling value constituting the asynchronous data using the information output from the remainder accumulating means Phase adjustment means for adjusting the position and outputting data composed of the adjusted sampling values as synchronization data; It can be adapted to.

  The switching determination unit can determine the first switching and the second switching based on the data string detected by the decoding unit.

  The data string detected by the decoding means can be predetermined information extracted from the channel bit string detected by the data detecting means.

  The predetermined information extracted from the channel bit string is the SYNC included in the channel bit string in the ideal state, and the switching determination means, when the SYNC is detected by the decoding means, the first switching and the second When the SYNC is not detected by the decoding means, it can be determined that the first switching and the second switching are performed.

  In the data reproduction method of the present invention, when data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the data reproducing method is performed according to the first algorithm or the second algorithm. A phase synchronization step for generating synchronous data synchronized with a predetermined frequency from the asynchronous data, and a third algorithm corresponding to the first algorithm or a fourth algorithm corresponding to the second algorithm A data detection step for detecting a channel bit string corresponding to the RLL recording code from the synchronization data generated by the phase synchronization means, a decoding step for decoding the channel bit string detected by the processing of the data detection step, a phase synchronization step, At least one of a data detection step and a decoding step First switching between the first algorithm and the second algorithm based on a data string that is generated, detected, or used and does not have identification information individually, and a third algorithm And a switching determination step for determining a second switching between the fourth algorithm and the fourth algorithm.

  The program of the present invention is a program corresponding to the above-described data reproduction method of the present invention.

  In the data reproducing apparatus, method, and program of the present invention, the first algorithm is used when data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency. Alternatively, in accordance with the second algorithm, synchronous data synchronized with a predetermined frequency is generated from the asynchronous data. Next, a channel bit string corresponding to the RLL recording code is detected from the synchronization data according to the third algorithm corresponding to the first algorithm or the fourth algorithm corresponding to the second algorithm. Then, the channel bit string is decoded. At this time, based on the data sequence generated, detected, or used during the series of processes described above and having no identification information, the first algorithm and the second algorithm 1 and the second switching between the third algorithm and the fourth algorithm are determined, and the presence or absence of the first switching and the second switching is controlled based on the determination result.

  According to the present invention, a data reproducing apparatus can be provided. In particular, the entire data reproducing apparatus (system) can be kept stable regardless of the difference in various setting conditions for the data reproducing apparatus.

  Embodiments of the present invention will be described below. Correspondences between constituent elements described in the claims and specific examples in the embodiments of the present invention are exemplified as follows. This description is to confirm that specific examples supporting the invention described in the claims are described in the embodiments of the invention. Therefore, even though there are specific examples that are described in the embodiment of the invention but are not described here as corresponding to the configuration requirements, the specific examples are not included in the configuration. It does not mean that it does not correspond to a requirement. On the contrary, even if a specific example is described here as corresponding to a configuration requirement, this means that the specific example does not correspond to a configuration requirement other than the configuration requirement. not.

  Further, this description does not mean that all the inventions corresponding to the specific examples described in the embodiments of the invention are described in the claims. In other words, this description is an invention corresponding to the specific example described in the embodiment of the invention, and the existence of an invention not described in the claims of this application, that is, in the future, a divisional application will be made. Nor does it deny the existence of an invention added by amendment.

According to the present invention, a data reproducing apparatus is provided. This data reproducing apparatus (for example, the data reproducing apparatus shown in FIGS. 10, 17, 18, 20, 21, 22, etc., however, for the sake of simplicity, the correspondence with the data reproducing apparatus shown in FIG. Only explained)
A data reproducing device for reproducing data,
When data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the asynchronous data is read from the asynchronous data according to the first algorithm or the second algorithm. Phase synchronization means for generating synchronization data synchronized with a predetermined frequency (for example, the PLL unit 31 in FIGS. 10 and 11);
A channel corresponding to the RLL recording code from the synchronization data generated by the phase synchronization means according to a third algorithm corresponding to the first algorithm or a fourth algorithm corresponding to the second algorithm Data detection means for detecting a bit string (for example, the PRML unit 33 in FIG. 10);
Decoding means for decoding the channel bit string detected by the data detection means (for example, sync detection / decoding unit 34 in FIG. 10);
Based on the data string that is generated, detected, or used by at least one of the phase synchronization means, the data detection means, and the decoding means, and does not have identification information individually, Switching determination means for determining the first switching between the first algorithm and the second algorithm and the second switching between the third algorithm and the fourth algorithm (for example, the switching determination in FIG. 10). And a control unit 32).

In this data reproducing apparatus,
The phase synchronization means uses two or more sampling values in a predetermined section of the synchronization data and two or more temporary determination values for each of the two or more sampling values in the predetermined section. And phase error information detecting means (for example, phase error information detecting unit 41 in FIG. 11) for detecting phase error information indicating the phase error of the synchronization data,
The switching determination unit determines the first switching and the second switching based on two or more provisional determination values used by the phase error information detection unit of the phase synchronization unit. be able to.

In this data reproducing apparatus,
The phase synchronization means includes
First phase error information detection means (for example, the first phase error detection unit 52-1 in FIG. 11) for detecting phase error information indicating the phase error of the synchronization data according to the first algorithm;
The second phase error information detecting means (for example, the second phase error detecting unit 52-2 in FIG. 11) for detecting the phase error information according to the second algorithm;
When the switching determination information generated by the switching determination unit includes information that the first switching is performed, the first phase error information detection unit and the second phase error information detection unit Switch from one currently in use to the other,
When the switching determination information generated by the switching determination unit includes information indicating that the first switching is not performed, the first phase error information detection unit and the second phase error information detection unit The switch from one currently used to the other can be prohibited.

In this data reproducing apparatus,
Each of the first phase error information detection means and the second phase error information detection means includes two or more sampling values in a predetermined section of the synchronization data, and two or more in the predetermined section. Using the two or more provisional determination values for each of the sampling values of, detecting the phase error information,
The phase synchronization means further includes
According to the first algorithm, a first temporary determination value calculating means (for example, the first slice unit 51-1 in FIG. 11) for calculating the temporary determination value;
According to the second algorithm, the second temporary determination value calculation means (for example, the second slice unit 51-2 in FIG. 11) for calculating the temporary determination value,
When the switching determination information generated by the switching determination unit includes information indicating that the first switching is performed, further, the first temporary determination value calculation unit and the second temporary determination value calculation unit Of which one is currently being used and switched to the other,
When the switching determination information generated by the switching determination unit includes information that the first switching is not performed, the first temporary determination value calculation unit and the second temporary determination value calculation unit Of these, switching from one currently used to the other can be prohibited.

In this data reproducing apparatus,
The data detection means includes
First data detecting means (for example, the first PRML unit 33-1 in FIG. 10) for detecting the channel bit string from the synchronization data according to the third algorithm;
Second data detection means (for example, the first PRML unit 33-2 in FIG. 10) for detecting the channel bit string from the synchronization data according to the fourth algorithm,
When the switching determination information generated by the switching determination unit includes information indicating that the second switching is performed, the switching determination information is currently used between the first data detection unit and the second data detection unit. Is switched from one to the other,
When the switching determination information generated by the switching determination unit includes information that the second switching is not performed, the current use of the first data detection unit and the second data detection unit Switching from one to the other can be prohibited.

In this data reproducing apparatus (however, here, for example, the data reproducing apparatus in FIG. 17),
The data reproduction apparatus further includes waveform shaping means (for example, EQ unit 3 in FIG. 17) that shapes the asynchronous data generated by the sampling means to a predetermined waveform and outputs the asynchronous data after shaping.
The phase synchronization means generates the synchronization data from the asynchronous data output from the waveform shaping means,
When the switching determination information generated by the switching determination unit includes information that at least one of the first switching and the second switching is performed, a predetermined setting value for the waveform shaping unit is changed. And
When the switching determination information generated by the switching determination unit includes information indicating that neither the first switching nor the second switching is performed, the change of the predetermined setting value with respect to the waveform shaping unit is prohibited. Can be done.

The data reproduction device (here, for example, the data reproduction device of FIG. 17) further includes gain control (AGC: Auto Gain Control) and DC (Direct Current) offset cancellation of the asynchronous data output from the waveform shaping means ( DCC: DC Cancel), AGC / DCC means (for example, AGC / DCC unit 4 in FIG. 17) for outputting the asynchronous data after AGC and DCC is provided,
The phase synchronization means generates the synchronization data from the asynchronous data output from the AGC / DCC means,
When the switching determination information generated by the switching determination unit includes information indicating that at least one of the first switching and the second switching is performed, a predetermined setting for the AGC / DCC unit is further provided. The value is changed,
When the switching determination information generated by the switching determination unit includes information indicating that neither the first switching nor the second switching is performed, the change of the predetermined setting value for the AGC / DCC unit is performed. It can be prohibited.

This data reproducing apparatus (here, the data reproducing apparatus in FIG. 10) is further
Differentiating means for generating a differential response signal of the analog signal when the data recorded on the predetermined recording medium as an RLL recording code of d> 0 is read from the predetermined recording medium as an analog signal ( For example, the differential filter unit 1) of FIG.
Sampling means (for example, the A / D converter 2 in FIG. 10) that generates the asynchronous data by sampling the analog differential response signal generated by the differentiating means asynchronously with the predetermined frequency. ,
The phase synchronization means can generate the synchronization data from the asynchronous data generated by the sampling means.

In the data reproducing apparatus, the phase synchronization means (for example, the PLL unit 31 in FIG. 11)
In accordance with the first algorithm or the second algorithm, phase error information detection means (for example, phase error information detection unit 41 in FIG. 11) for detecting phase error information indicating a phase error of the synchronization data;
A loop filter unit (for example, the loop filter unit 13 in FIG. 11) that performs a loop filter calculation using at least the phase error information detected by the phase error information detection unit and outputs the calculation result;
Performs a predetermined accumulation process on the calculation result output from the loop filter means, and generates information necessary for adjusting the phase position of each sampling value constituting the asynchronous data based on the process result And a residue accumulation means (for example, residue accumulation unit 14 in FIG. 11),
Using the information output from the residue accumulation means, the phase position of each sampling value constituting the asynchronous data is adjusted, and the data constituted by the adjusted sampling values is used as the synchronization data. And an output phase adjusting means (for example, the interpolation filter unit 11 in FIG. 11).

According to the present invention, a data reproduction method is provided. This data playback method is
When data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the asynchronous data is read from the asynchronous data according to the first algorithm or the second algorithm. A phase synchronization step (for example, step S5 in FIG. 2) for generating synchronization data synchronized with a predetermined frequency;
A channel corresponding to the RLL recording code from the synchronization data generated by the phase synchronization means according to a third algorithm corresponding to the first algorithm or a fourth algorithm corresponding to the second algorithm A data detection step (for example, step S6 in FIG. 2) for detecting a bit string;
A decoding step (for example, step S7 in FIG. 2) for decoding the channel bit string detected by the data detection step;
Based on the data sequence that is generated, detected, or used by at least one of the phase synchronization step, the data detection step, and the decoding step and does not have identification information individually, A switching determination step for determining the first switching between the first algorithm and the second algorithm and the second switching between the third algorithm and the fourth algorithm (for example, switching determination in FIG. 12). Processing) and.

  According to the present invention, a program corresponding to the above-described data reproducing method of the present invention and a recording medium on which the program is recorded are provided. As will be described later, this program is executed by, for example, a computer having the configuration shown in FIG.

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

  FIG. 1 shows a configuration example of an embodiment of a data reproducing apparatus to which the present invention is applied or a data reproducing apparatus including a phase synchronization apparatus to which the present invention is applied.

  The data reproducing apparatus can reproduce data recorded on a recording medium such as a magnetic disk, an optical disk, and a magneto-optical disk.

  Therefore, before describing the data reproducing apparatus of FIG. 1, data recorded on the recording medium will be described.

  That is, when data is recorded on a recording medium as in the present embodiment or transmitted to a predetermined transmission path, the data is modulated so as to be suitable for the recording medium and the transmission path.

  A block code is known as one of such modulation methods. In this block code, a data string is blocked into units of m × i bits (hereinafter referred to as data words), and the data words are converted into code words of n × i bits according to an appropriate coding rule. . This code becomes a fixed length code when i = 1, and when a plurality of i can be selected, that is, when a predetermined i in the range of 1 to imax (maximum i) is selected and converted, Become. The block-coded code is represented as a variable length code (d, k; m, n; r). Hereinafter, the variable length code (d, k; m, n; r) is appropriately referred to as an RLL code (Run Length Limited Code).

  Here, i is referred to as a constraint length, and imax is r (maximum constraint length). D indicates the minimum continuous number of “0”, for example, “0” minimum run, which falls between consecutive “1” s, and k indicates the maximum continuous of “0”, which falls between consecutive “1” s. The number, for example, the maximum run of “0” is shown.

  More specifically, in order to perform recording with high density in the linear velocity direction, where Tmin is the minimum inversion interval of the recording waveform sequence (the RLL code is NRZI-modulated as will be described later) and Tmax is the maximum inversion interval. In this case, it is preferable that the minimum inversion interval Tmin is longer, that is, d is larger, and that the maximum inversion interval Tmax is shorter, that is, the maximum run k is smaller in terms of clock reproduction. In order to satisfy the above, various modulation methods have been proposed.

  More specifically, for example, RLL (1-7) ((1, 7; m, n), which is a variable-length code, is used as a modulation method proposed or actually used in an optical disk, a magnetic disk, a magneto-optical disk, or the like. ; Also expressed as r)) and RLL (2-7) (also expressed as (2, 7; m, n; r)), and fixed length RLL (1-7) used in ISO standard MO (Also expressed as (1, 7; m, n; 1)).

  In disk devices such as optical disks and magneto-optical disks with high recording density that are currently being researched and developed, d = 1 RLL codes are often used, for example, variable-length RLL (1-7) codes.

  The parameter of the variable length RLL (1-7) is (1, 7; 2, 3; 2), and the minimum inversion interval Tmin represented by (d + 1) T is 2 where T is the bit interval of the recording waveform sequence. (= 1 + 1) T. Assuming that the bit interval of the data string is Tdata, the minimum inversion interval Tmin represented by (m / n) × 2 is 1.33 (= (2/3) × 2) Tdata. The maximum inversion interval Tmax represented by (k + 1) T is 8 (= 7 + 1) T ((= (m / n) × 8Tdata = (2/3) × 8Tdata = 5.33Tdata) Further, the detection window width. Tw is represented by (m / n) × Tdata, and its value is 0.67 (= 2/3) Tdata.

  When the occurrence frequency of T in the channel bit string modulated by RLL (1-7) is examined, 2T, which is Tmin, is the largest, followed by 3T, 4T, and 5T. The occurrence of a large amount of edge information such as 2T or 3T at an early cycle is often advantageous for clock recovery.

  The 17PP code adopted in the Blu-ray Disc ReWritable Format is based on the RLL (1-7) code, and the minimum run, the maximum run, and the basic conversion rate are the same. Furthermore, the continuation of the minimum run 2T is limited to a finite number of times, and the relationship between the data string and the conversion code string is regular in the number of “1” s in the table, and when DSV (Digital Sum Value) is controlled It is a format that can be done efficiently.

  DSV control refers to the following control.

  That is, when data is recorded on a recording medium or when data is transmitted, encoding modulation suitable for the recording medium or transmission path is performed. These modulation codes include a direct current component and a low frequency component. For example, various error detection signals such as tracking errors in the servo control of the disk device are likely to fluctuate or jitter is likely to occur. Therefore, it is better to avoid the DC component and the low frequency component as much as possible in the modulation code.

  Therefore, it has been proposed to control the DSV. In this DSV, the RLL code is level-coded (for example, NRZI modulation described later), and the code is added with “1” being “+1” and “0” being “−1” in the bit string (data symbol). This is called DSV control. Decreasing the absolute value of the DSV transition that is a measure of the DC component and low-frequency component of the code string, that is, performing DSV control, suppresses the DC component and low-frequency component of the code string.

  Note that DSV control is not performed on the modulation code based on the variable length RLL (1-7). Since conversion efficiency is good, DSV control cannot be performed at the time of modulation like, for example, 8-16 code of DVD (Digital Versatile Disk). In such a case, DSV control is performed by, for example, performing DSV calculation at a predetermined interval in a modulated encoded string (channel bit string), and as a DSV control bit at a predetermined position in the encoded string (channel bit string). This is realized by inserting.

  However, the DSV control bit is basically a redundant bit. Therefore, from the viewpoint of code conversion efficiency, it is better to have as few DSV control bits as possible.

  As described above, in the present embodiment, such an RLL code is recorded on a recording medium.

  More precisely, when such an RLL code is recorded on a recording medium such as an optical disk or a magneto-optical disk, for example, in a compact disk or a mini-disc, “1” is inverted and “0” is omitted in the RLL code. NRZI (Non Return to Zero Inverted) modulation, which is inverted, is performed, and recording based on a variable-length code (hereinafter also referred to as a recording waveform sequence) that has been subjected to NRZI modulation is often performed. However, in addition to this, in the early ISO (International Organization for Standardization) magneto-optical disk where the recording density was not so high, the recording-modulated bit string was recorded as it was without being subjected to NRZI modulation.

  In the present embodiment, the RLL code (hereinafter referred to as RLL recording code) recorded on a recording medium such as an optical disk or a magneto-optical disk in this way is reproduced by the data reproducing apparatus of FIG. Furthermore, in the present embodiment, an RLL recording code with d> 0 is reproduced by the data reproducing apparatus of FIG.

  That is, for example, an RLL recording code recorded on a recording medium is read as an RF (Radio Frequency) signal (hereinafter referred to as a reproduction RF signal) by a head (not shown) or the like and input to the data reproduction apparatus of FIG. .

  Therefore, the data reproducing apparatus in FIG. 1 restores the original data from the reproduced RF signal and outputs it. For this reason, in the example of FIG. 1, the data reproducing apparatus is configured from the differential filter unit 1 to the decoding unit 7.

  An example of the data reproduction process of the data reproduction apparatus having such a configuration is shown in the flowchart of FIG. An example of the data reproduction process of the data reproduction apparatus in FIG. 1 will be described below with reference to the flowchart in FIG. In addition, when the processing of each step in the flowchart of FIG. 2 is described, the block that executes the processing of the step to be described in the differential filter unit 1 to the decoding unit 7 will also be described.

  In step S <b> 1, the differential filter unit 1 generates a differential response signal of the reproduction RF signal and supplies it to the A / D conversion unit 2. That is, the differential filter unit 1 is constituted by, for example, a differential filter as the name suggests.

  In step S2, the A / D (Analog / Digital) converter 2 performs digital sampling by asynchronously sampling the analog differential response signal at a predetermined sampling frequency asynchronous with the target channel clock (write frequency) fch. Asynchronous sampling data is generated and supplied to the EQ unit 3.

  Note that the sampling frequency used in the process of step S2 may be set to a frequency that is smaller than twice the channel clock fch and slightly higher than the same size, for example. For example, in this embodiment, the sampling frequency is n / m times the channel clock fch. Specifically, for example, m = 7 and n = 8, and fch * 8/7, that is, the channel clock. It is 8/7 times that of fch.

  In step S3, the EQ unit 3 shapes the asynchronous sampling data supplied from the A / D conversion unit 2 into a predetermined waveform. For example, in the present embodiment, the EQ unit 3 is configured as an equalizer to which a fixed coefficient is given at 5 taps, and asynchronous sampling data is shaped into a predetermined waveform by each of the fixed coefficients for 5 taps. Is done.

  When the asynchronous sampling data shaped into a predetermined waveform is provided from the EQ unit 3 to the AGC / DCC unit 4, the process proceeds to step S4. In step S4, the AGC / DCC unit 4 performs non-sampling data gain control (AGC: Auto Gain Control) and DC (Direct Current) offset cancellation (DCC: DC Cancel).

  The AGC / DCC unit 4 may obtain information from other blocks and perform predetermined calculations as necessary.

  When asynchronous sampling data subjected to gain control and DC offset cancellation is provided from the AGC / DCC unit 4 to the PLL unit 5, the process proceeds to step S5. In step S5, the PLL (Phase Locked Loop) unit 5 converts the asynchronous sampling data into synchronous sampling data synchronized with the channel clock fch.

  Although details will be described later, an algorithm corresponding to PR (1, -1) equalization or PR (1,0, -1) equalization is given to the PLL unit 5, and as a result, the PLL unit 5 The synchronous sampling data output from is a digital signal shaped to PR (1, -1) equalization or PR (1,0, -1) equalization.

  When the synchronous sampling data is provided from the PLL unit 5 to the PRML unit 6, the process proceeds to step S6. In step S6, the PRML unit 6 uses the Partial Response Maximum Likelihood (PRML) method that combines the Partial Response (PR) method and the Maximum Likelihood Sequence Detection (ML) method, and performs synchronous sampling. The RLL code (0 or 1 channel bit) is detected from the data.

  Note that Viterbi detection (Viterbi decoding) is mainly used as the maximum likelihood decoding. However, the data detection method of the PRML unit 6 is not particularly limited to Viterbi decoding. For example, a method using an NPML code may be used, or a simple slice detection method may be used.

  When the RLL code is supplied from the PRML unit 6 to the decoding unit 7, the process proceeds to step S7. In step S7, the decoding unit 7 decodes the RLL code (channel decoding = encoding decoding), and outputs the original data string obtained as a result.

  The data reproduction process executed by the data reproduction apparatus having the configuration shown in FIG. 1 has been described above.

  By the way, for example, instead of the PLL unit 5 (see FIG. 11 for the detailed configuration) to which the present invention is applied to the data reproducing apparatus having the configuration of FIG. Consider a playback device with a PLL section. That is, FIG. 3 shows a configuration example of a conventional PLL unit.

  In the example of FIG. 3, the conventional PLL unit is configured as a Digital ITR type PLL circuit. For this reason, in the example of FIG. 3, the interpolation filter unit 11 to the remainder accumulation unit 14 are provided in the conventional PLL unit.

  The interpolation filter unit 11 is configured as an interpolation filter having a filter coefficient for converting the asynchronous sampling data input from the AGC / DCC unit 4 of FIG. 1 into synchronous sampling data. That is, the interpolation filter unit 11 selects a predetermined one from a plurality of filter coefficients based on the information supplied from the remainder accumulating unit 14, and determines the phase of the asynchronous sampling data corresponding to the selected filter coefficient. Just shift. As a result, the sampling data output from the interpolation filter unit 11 is close to the synchronous sampling data.

  In other words, in a transition period or the like, the sampling data output from the interpolation filter unit 11 is not yet accurately synchronized with the channel frequency fch. That is, there is a phase error in the sampling data output from the interpolation filter unit 11. For this reason, the PLL unit performs feedback control to make the phase error as close to 0 as possible, and as a result, outputs the sampling data substantially synchronized with the channel frequency fch. In order to perform such feedback control, in addition to the interpolation filter unit 11, a phase error information detection unit 12, a loop filter unit 13, and a residue accumulation unit 14 are provided. That is, the interpolation filter unit 11 to the remainder accumulation unit 14 constitute a feedback loop.

  However, in the following description, the sampling data output from the interpolation filter unit 11 are collectively referred to as synchronous sampling data. That is, even sampling data that includes some phase error is referred to as synchronous sampling data.

  The phase error information detection unit 12 is provided with an algorithm corresponding to, for example, PR (1, -1) equalization, detects information indicating the phase error of synchronous sampling data (hereinafter referred to as phase error information), Provided to the loop filter unit 13.

  Specifically, the phase error information detection unit 12 includes a slice unit 21 and a phase error detection unit 22.

  Hereinafter, the synchronous sampling data for which the phase error is detected by the phase error information detection unit 12, that is, the sampling value of the current processing target is referred to as data_now. On the other hand, the synchronous sampling data immediately before data_now is referred to as data_D.

  In this case, the slicing unit 21 tentatively determines a value that data_now can originally take by comparing the actual value of data_now with a predetermined threshold th, and uses the tentative determination value (hereinafter referred to as a slice value) as a phase. The error detection unit 22 is provided.

  Specifically, for example, since the synchronous sampling data is a digital signal shaped by PR (1, -1) equalization here, 1, 0, -1 is a value that data_now can originally take. That is, for example, in the present embodiment, the slicing unit 21 determines which of the following inequalities (1) to (3) the data_now satisfies.

data_now ≧ th (1)
th>data_now> -th (2)
-th ≧ data_now (3)

  When the inequality (1) is satisfied, the slice unit 21 is 1. When the inequality (2) is satisfied, the slice value is 0. When the inequality (3) is satisfied, the slice unit 21 satisfies the inequality (3). Each slice value is determined to be −1, and the determined slice value is provided to the phase error detector 22.

  The phase error detection unit 22 calculates the phase_err as phase error information by calculating the right side of the next Mueller & Mueller equation (4), and provides it to the loop filter unit 13. In Expression (4), slice_now indicates a slice value corresponding to data_now, and slice_D indicates a slice value corresponding to data_D.

  phase_err = (data * slice_D)-(data_D * slice_now) (4)

  The loop filter unit 13 performs a loop filter operation using a predetermined loop filter coefficient and a predetermined initial value as required in addition to the phase error information supplied from the phase error detection unit 22, and the calculation The result is provided to the remainder accumulation unit 14.

  The remainder accumulation unit 14 performs a predetermined accumulation process on the loop filter calculation result of the loop filter unit 13, generates information necessary for the interpolation filter unit 11 based on the processing result, and stores the information in the interpolation filter unit 11. Provide necessary enable information for other blocks.

  In the conventional PLL section having such a configuration, the above-described conventional problems occur. Therefore, the present inventor has invented a technique capable of ascertaining the cause of occurrence of a conventional problem and removing the cause.

  Hereinafter, first, the cause of the conventional problem will be described with reference to FIGS.

  FIG. 4 shows an ideal output waveform when the minimum run 2T (= d + 1) is continuous when PR (1, -1) equalization is performed using the RLL recording code of d = 1.

  That is, when PR (1, -1) equalization is performed using an RLL recording code with d = 1, the output at the time of continuous 2T is 1,0, -1,0,1,0, -1, ... Therefore, the output waveform can be regarded as a simple sin waveform as shown in FIG.

  In this case, an ideal sample position in PR (1, -1) equalization by the PLL unit, that is, an ideal phase position of the synchronous sampling data from the interpolation filter unit 11 (a position where no phase error exists), in other words, Then, ideal phase positions of data_now and data_D are phase positions of 0, 90, 180, 270, and 360 as shown in FIG.

  When synchronous sampling data of such ideal phase position is output from the interpolation filter unit 11, the threshold value th used by the slice unit 12, that is, the inequalities (1) to (3) is used. If the threshold value th to be set is 0.5, for example, the combination of slice_D and slice_now (slice_D, slice_now) is (0, -1), (0, 1), (1, 0), and (-1, 0) It becomes either. Therefore, in this case, phase_err is always 0 based on the above-described equation (4). That is, the phase error detection unit 22 outputs 0 (meaning that no phase error exists) to the loop filter unit 13 as phase error information. In other words, it can be said that the phase error detector 22 does not generate output of phase error information.

  However, if the synchronous sampling data at the phase position of 0, 90, 180, 270, 360 includes a value due to noise or the like, that is, the value at the position of 0, 90, 180, 270, 360 is 0, 1, If a value resulting from noise or the like is added to −1, phase_err has a value other than 0, so that phase error information is output.

  Even when the phase position of the synchronous sampling data from the interpolation filter unit 11 is slightly shifted from the ideal position (positions 0, 90, 180, 270, 360), the combination of slice_D and slice_now (slice_D, slice_now) ) Is one of (0, -1), (0, 1), (1, 0), and (-1, 0). Accordingly, in such a case, even if there is no noise or the like, phase_err has a value other than 0, so that output of phase error information occurs.

  Therefore, when the phase position of the synchronous sampling data from the interpolation filter unit 11 is slightly deviated from the ideal position (positions 0, 90, 180, 270, 360), the ideal position is obtained by the above-described feedback control of the PLL unit. It will converge to (0, 90, 180, 270, 360 positions). That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 disappears.

  However, the phase position of the synchronous sampling data from the interpolation filter unit 11, in other words, the phase position of data_now and data_D further shifts, and as shown in FIG. 5, the ideal position (0, 90, 180, 270, 360). (Slice_D, slice_now), (0, -1), (0, 1), (1, 0), and (-1, 0) No longer exists. That is, as (slice_D, slice_now), it cannot occur when an RLL code of d = 1 is applied to PR (1, -1) equalization, (1, -1), (1, 1), (-1, 1) and (-1, -1) are generated. As a result, phase_err is always 0 from the above-described equation (4). That is, the phase error detection unit 22 outputs 0 (meaning that no phase error exists) to the loop filter unit 13 as phase error information even though 45 phase errors exist.

  In FIG. 5, if the values at the phase positions of 45, 135, 225, and 315, that is, the value of the synchronous sampling data falls below th = 0.5 or exceeds -th = -0.5 due to noise or the like, (slice_D, slice_now) , (0, -1), (0, 1), (1, 0), and (-1, 0) will exist, and output of phase error information will occur. . However, as is apparent from FIG. 5, the values at the 45,135 phase positions are much higher than th = 0.5, and the values at the phase positions of 225, 315 are much lower than -th = -0.5, even if synchronous sampling is performed. Even if the data contains a lot of noise etc., the probability that the value falls below th = 0.5 or exceeds -th = -0.5 is low.

  After all, when the phase position of the synchronous sampling data from the interpolation filter unit 11 is slightly deviated from the position (45, 135, 225, 315, 405) deviated by 45 from the ideal position, the above-mentioned PLL unit The feedback control results in convergence at a position (45, 135, 225, 315, 405) that is deviated by 45 from the ideal position. That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 remains approximately 45, and the phase error does not disappear.

  More precisely, if the phase position of data_D and data_now is the phase position when only one of data_D and data_now exceeds a predetermined threshold, the phase position is This is called the back phase. In this case, when the back phase is reached, the above-described feedback control of the PLL unit converges to a position shifted by 45 from the ideal position (positions 45, 135, 225, 315, and 405). That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 remains approximately 45, and the phase error does not disappear.

  The above description applies to the case where the minimum run other than 2T is continued. For example, when PR (1, -1) equalization is performed using an RLL recording code of d = 1, the output when the minimum run 3T is continuous is 0, 1, 0, 0, -1, 0, 0 , 1, 0, 0, -1, 0, 0,. Therefore, the output waveform can be regarded as a waveform as shown in FIG. That is, FIG. 6 is a diagram illustrating a state where the phase position of the synchronous sampling data from the interpolation filter unit 11 is an ideal position (positions 0, 90, 180, 270, and 360). On the other hand, FIG. 7 is a diagram showing a state in which the phase position of the synchronous sampling data from the interpolation filter unit 11 is shifted by 45 from the ideal position.

  As is clear from FIG. 6, even when the output of the minimum run 3T is continuous, the phase position of the synchronous sampling data from the interpolation filter unit 11 is the ideal position (positions 0, 90, 180, 270, 360). In some cases, (slice_D, slice_now) generates (0, -1), (0, 1), (1, 0), and (-1, 0). On the other hand, if the phase position of the synchronous sampling data from the interpolation filter unit 11 deviates by 45 from the ideal position, it does not naturally occur as (slice_D, slice_now) (1, 1), (-1, -1) occurs, and (0, -1), (0, 1), (1, 0), and (-1, 0) occur with a phase shift.

  Although not shown in the drawings, if the minimum run 4T is continuous, the output is 1, 0, 0, 0, -1, 0, ..., and if the minimum run 5T is continuous, 1, 0, 0, 0, 0, -1, 0,..., And 1, 0, 0, 0, 0, 0, -1, 0,. For example, in the case of RLL (1, 7), since d = 1 and the maximum run k = 7, there are 2T to 8T. In most cases, however, there is actually a larger T such as 10T due to Sync-code.

  In any case, when the phase position of the synchronous sampling data from the interpolation filter unit 11 is an ideal position regardless of the minimum run, (0, −1), (0, 1) is set as (slice_D, slice_now). , (1, 0), and (-1, 0) are generated. On the other hand, if the phase position of the synchronous sampling data from the interpolation filter unit 11 deviates by 45 from the ideal position, it does not naturally occur as (slice_D, slice_now) (1, 1), (-1, -1) occurs, and (0, -1), (0, 1), (1, 0), and (-1, 0) occur with a phase shift.

  Therefore, when the phase position of the synchronous sampling data from the interpolation filter unit 11 becomes a reverse phase, the phase is converged to a position shifted from the ideal position by the above-described feedback control of the PLL unit. That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 is not lost. This is considered to be a cause of the above-mentioned conventional problems.

  Specifically, for example, FIG. 8 shows a state in which the conventional PLL unit is normally locked, that is, a state where the phase position of the synchronous sampling data from the interpolation filter unit 11 is substantially at the ideal position. That is, FIG. 8 shows normal synchronous sampling data obtained as a result when the conventional PLL unit synchronizes the phase of asynchronous sampling data by PLL (1, -1) equalization. In FIG. 8, the horizontal axis indicates time, and the vertical axis indicates the amplitude level. Further, the threshold th is 32 [Level], and (−0.50, 0.25, 1.50, 0.25, −0.50) is given as 5 taps in the EQ unit 3 in FIG. The error rate during eye pattern was about 3e-4 in bytes. As shown in FIG. 8, since the eye (white portion near the threshold value: gap between two black portions) is open, the phase position of the synchronous sampling data is almost ideal even in a waveform including actual disturbance. It turns out that it has converged toward the position.

  However, when the phase position of the synchronous sampling data from the interpolation filter unit 11 becomes the back phase, the conventional PLL unit is at a predetermined phase position of the back phase (position shifted 45 degrees from the ideal position, etc.). As a result, the asynchronous sampling data becomes as shown in FIG. In this case, as shown in FIG. 9, it can be seen that the eye state has collapsed. In other words, an eye in which PR (1, -1) equalization is normally performed in the partial portion (an eye around ± 60 [Level]) can be confirmed, but other PR equalization (PR ( 1,0, -1) Equalization) is performed (eye around ± 30 [Level]). In other words, the fact that the conventional PLL section locks at a predetermined phase position of the back phase (position shifted by 45 degrees from the ideal position, etc.) means that the conventional PLL section has a different PR equalization (PR (1, 1, 0, -1) equalization).

  Therefore, in the eye portion where PR (1, -1) equalization is normally performed, an error rate similar to that in FIG. 8 can be obtained (though the error rate is good to some extent) When the eye is broken, that is, when the conventional PLL unit is locked at a predetermined phase position of the back phase, the channel detected by the PRML unit 6 corresponding to PR (1, -1) in FIG. Bits will not match at all, or SYNC will not be possible. As a result, the error rate cannot be obtained at all. That is, the conventional problem occurs.

  The phenomenon that the conventional PLL unit is locked at the predetermined phase position of the back phase is not related to the reproduction quality, but the AGC of the AGC / DCC unit 4 in FIG. This may occur depending on the setting of DCC, the tap of the EQ unit 3, or the setting of the threshold th of the slice of the conventional PLL unit.

  Therefore, the present inventor has invented the following method in order to solve such problems.

  That is, it is determined whether or not the phase position of the synchronous sampling data from the PLL unit is the reverse phase. If the phase is not the reverse phase, the calculation result of the above equation (4) is used as the phase error information. However, the inventors have invented a method of using phase error information different from the equation (4) when the back phase is reached. However, more precisely, when d = 1 and PR (1,0, -1) are not in the reverse phase, basically, the calculation result of Equation (4) is used as the phase error information. However, if the transition from data_D to data_now is 0 → ± 1 or ± 1 → 0, 0 is used as phase error information. This is because these transitions can occur both in and out of phase.

  Although not shown, the data reproduction apparatus of FIG. 1 can solve the above-described problems by employing a PLL to which the technique of the present invention is applied as the PLL unit 5 of FIG.

  Incidentally, FIG. 5 shows an output waveform in the back phase state when the minimum run 2T (= d + 1) continues when PR (1, -1) equalization is performed using the RLL recording code of d = 1. However, from a different point of view, the minimum run 2T (= d + 1) is continuous when PR (1,0, -1) equalization is performed using the RLL recording code with d = 1. It can be said that it shows an ideal output waveform.

  Similarly, FIG. 7 shows the output waveform in the back phase state when the minimum run 3T (= d + 1) continues when PR (1, -1) equalization is performed using the RLL recording code of d = 1. In other words, the minimum run 2T (= d + 1) is continuous when PR (1,0, -1) equalization is performed using the RLL recording code with d = 1. It can be said that this shows an ideal output waveform.

  This will be described in more detail.

  That is, when PR (1,0, -1) equalization is performed using an RLL recording code of d = 1, the output at the time of continuous 2T is 1,1, -1, -1, -1,1, -1, -1, .... Therefore, the output waveform can be regarded as a simple sin waveform as shown in FIG.

  In this case, an ideal sample position in PR (1,0, -1) equalization by the PLL unit, that is, an ideal phase position of the synchronous sampling data from the interpolation filter unit 11 (a position where no phase error exists). In other words, the ideal phase positions of data_now and data_D are the phase positions of 45, 135, 225, and 315 as shown in FIG.

  When synchronous sampling data of such ideal phase position is output from the interpolation filter unit 11, the threshold value th used by the slice unit 12, that is, the inequalities (1) to (3) is used. If the threshold value th to be set is 0.5, for example, the combination of slice_D and slice_now (slice_D, slice_now) is (1, 1), (-1, 1), (1, -1), and (-1,- It will be one of 1). Therefore, in this case, phase_err is always 0 based on the above-described equation (4). That is, the phase error detection unit 22 outputs 0 (meaning that no phase error exists) to the loop filter unit 13 as phase error information. In other words, it can be said that the phase error detector 22 does not generate output of phase error information.

  However, if the synchronous sampling data at the phase positions of 45, 135, 225, and 315 includes values caused by noise or the like, that is, the values at the positions of 45, 135, 225, and 315 are 0, 1, and −1. If the value due to noise or the like is added, phase_err has a value other than 0, and therefore output of phase error information occurs.

  In addition, when the phase position of the synchronous sampling data from the interpolation filter unit 11 is slightly shifted from the ideal position (positions 45, 135, 225, and 315), the combination of slice_D and slice_now (slice_D, slice_now) , (1, 1), (-1, 1), (1, -1), and (-1, -1). Accordingly, in such a case, even if there is no noise or the like, phase_err has a value other than 0, so that output of phase error information occurs.

  Accordingly, when the phase position of the synchronous sampling data from the interpolation filter unit 11 is slightly shifted from the ideal position (positions of 45, 135, 225, and 315), the ideal position (45 , 135, 225, and 315). That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 disappears.

  However, the phase position of the synchronous sampling data from the interpolation filter unit 11, in other words, the phase position of data_now and data_D further shifts, and as shown in FIG. 4, the ideal positions (positions 45, 135, 225, and 315). ), When (45) is shifted by 45, (1, -1), (1, 1), (-1, 1), (-1, -1) exist as (slice_D, slice_now) This time, (0, -1), (0, 1), (1, 0), and (-1,0) are generated. As a result, phase_err is always 0 from the above-described equation (4). That is, the phase error detection unit 22 outputs 0 (meaning that no phase error exists) to the loop filter unit 13 as phase error information even though 45 phase errors exist.

  Note that (0, -1), (0, 1), (1, 0), and (-1,0) as (slice_D, slice_now) can exist even in a normal ideal time as shown in FIG. This will be described later.

  In FIG. 4, if the value at the phase position of 0, 90, 180, 270, 360, that is, the value of the synchronous sampling data falls below th = 0.5 due to noise or the like, or exceeds -th = -0.5, (slice_D , Slice_now), any one of (1, -1), (1, 1), (-1, 1), (-1, -1) exists, and the output of phase error information is Will occur. However, as is clear from FIG. 4, even if the synchronous sampling data includes a lot of noise and the like, the probability that the value is less than th = 0.5 or more than -th = -0.5 is low.

  Therefore, when the phase position of the synchronous sampling data from the interpolation filter unit 11 is slightly deviated from the position deviated by 45 from the ideal position (phase position of 0, 90, 180, 270, 360), the above-described PLL unit is described above. As a result, the feedback control results in convergence to a position (phase position of 0, 90, 180, 270, 360) that is shifted by 45 from the ideal position. That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 remains approximately 45, and the phase error does not disappear.

  More precisely, when the back phase is reached, it is converged to a position shifted by 45 from the ideal position (phase positions 0, 90, 180, 270, 360 in FIG. 4) by the above-described feedback control of the PLL section. It will end up. That is, the phase error of the synchronous sampling data from the interpolation filter unit 11 remains approximately 45, and the phase error does not disappear.

  As described above, FIG. 4 shows an ideal output when the minimum run 2T (= d + 1) continues when PR (1, -1) equalization is performed using the RLL recording code of d = 1. Although it has been explained that the waveform is shown, from a different point of view, the minimum run 2T (= d + 1) when PR (1,0, -1) equalization is performed using the RLL recording code of d = 1 It can also be said that the output waveform in the back phase state at the time of continuous is shown.

  The above description applies to the case where the minimum run other than 2T is continued. For example, when PR (1,0, -1) equalization is performed using an RLL recording code of d = 1, the output when the minimum run 3T is continuous is 0, 1, 1, 0, -1,- 1, 0, 1, 1, 0, -1, -1, 0,. Therefore, the output waveform can be regarded as a waveform as shown in FIG. That is, FIG. 7 is a diagram illustrating a state in which the phase position of the synchronous sampling data from the interpolation filter unit 11 is an ideal position (positions 45, 135, 225, and 315). On the other hand, FIG. 6 is a diagram showing a state in which the phase position of the synchronous sampling data from the interpolation filter unit 11 is shifted by 45 from the ideal position.

  Although not shown in the drawings, if the output is continuous for the minimum run 4T, it will be 1, 1, 0, 0, -1, -1,... , 0, 0, 0, -1, -1,..., And 1, 1, 0, 0, 0, 0, -1, -1,. It becomes. For example, in the case of RLL (1, 7), since d = 1 and the maximum run k = 7, there are 2T to 8T. In most cases, however, there is actually a larger T such as 10T due to Sync-code.

  The phenomenon that the conventional PLL unit is locked at the predetermined phase position of the back phase as described above, regardless of whether the reproduction quality is good or bad, is the AGC / DCC unit 4 in FIG. 1 before the conventional PLL unit. This may occur depending on the AGC or DCC setting, the tap setting of the EQ unit 3, or the slice threshold th of the conventional PLL unit. Further, in an actual waveform including disturbance, if these various settings are not appropriate, the entire system (data reproducing apparatus) becomes unstable.

  Thus, FIG. 6 shows an ideal output waveform when the minimum run 3T (= d + 2) is continuous when PR (1, -1) equalization is performed using the RLL recording code of d = 1. As described above, if the view is changed, the minimum run 3T (= d + 1) continuous when PR (1,0, -1) equalization is performed using the RLL recording code of d = 1 It can also be said that the output waveform in the back phase state is shown.

  In summary, the PR (1, -1) response at d = 1 is equivalent to the PR (1,0, -1) response when the sample position (data_now or data_D) is in the back phase. Conversely, there is a relationship that the PR (1,0, -1) response at d = 1 is equivalent to the PR (1, -1) response when there is a sample position in the back phase.

  Therefore, the present inventor further invented the following method using this relationship. That is, by observing the transition pattern of the slice value used in the PLL part, the partial response method is selected from PR (1, -1) and PR (1,0, -1) based on the transition pattern. The inventor further invented a method of switching from the one used to the other.

  As (slice_D, slice_now), (0, -1), (0, 1), (1, 0), (-1,0) are normal values of PR (1,0, -1) as described above. Since an ideal state and a back phase state can exist, in order to realize the mutual switching between PR (1, -1) and PR (1,0, -1), as will be described later, FIG. The phase_err algorithm shown in FIG. 16 may be used.

  A configuration example of a data reproducing apparatus to which the method of the present invention is applied is shown in FIG. That is, FIG. 10 shows a configuration example of an embodiment different from FIG. 1 of the data reproducing apparatus to which the present invention is applied. In the data reproducing apparatus in the example of FIG. 10, the same reference numerals are given to the portions corresponding to those in the example of the data reproducing apparatus in FIG.

  In the example of FIG. 10, the data reproducing apparatus includes a differential filter unit 1 to an AGC / DCC unit 4, a PLL unit 31, a switching determination control unit 32, a PRML unit 33, and a sync detection / decoding unit 34.

  The PLL unit 31 converts the asynchronous sampling data supplied from the AGC / DCC unit 4 into synchronous sampling data synchronized with the channel clock fch and supplies it to the PRML unit 33.

  Although details will be described later, the PLL unit 31 is provided with algorithms corresponding to PR (1, -1) equalization and PR (1,0, -1) equalization, respectively, and can be switched. Yes. That is, since the switching determination information chg is supplied from the switching determination control unit 32 to the PLL unit 31, the PLL unit 31 changes its algorithm to PR (1, -1) based on the switching determination information chg. Of equalization and PR (1,0, -1) equalization, switch from the currently used one to the other. As a result, the synchronous sampling data output from the PLL unit 31 becomes a digital signal shaped into PR (1, -1) equalization or PR (1,0, -1) equalization.

  Although details will be described later, the PLL unit 31 provides the switching determination control unit 32 with information necessary for the switching determination control unit 32 to perform switching determination (hereinafter referred to as switching determination index information). For example, in the present embodiment, the PLL unit 31 calculates the phase error information using the slice value, similarly to the conventional PLL unit of FIG. Further, as described above, the transition pattern of the normal ideal time of the slice value is different between PR (1, -1) equalization and PR (1,0, -1) equalization. In other words, the transition pattern of the back phase state is often the transition pattern at the ideal time for the other. Therefore, in the present embodiment, the PLL unit 31 supplies the slice value to the switching determination control unit 32 as switching determination index information.

  Further details of the PLL unit 31 will be described later with reference to FIG.

  The switching determination control unit 32 performs switching determination based on the switching determination index information supplied from the PLL unit 31, and uses the determination result as the switching determination information chg, in addition to the PLL unit 31 described above, and further to the PRML unit 33. Supply.

  The PRML unit 33 is configured to include a first PRML unit 33-1 and a second PRML unit 33-2. The first PRML unit 33-1 detects an RLL code from the synchronous sampling data supplied from the PLL unit 31 using a PRML method corresponding to PR (1, -1). On the other hand, the second PRML unit 33-2 detects an RLL code from the synchronous sampling data supplied from the PLL unit 31 using a PRML method corresponding to PR (1, 0, -1). . Switching between the first PRML unit 33-1 and the second PRML unit 33-2 is performed by the switching determination information chg from the switching determination control unit 32.

  The channel bit string (RLL code) output from the PRML unit 33 is supplied to the sync detection / decoder unit 34. The sync detection / decoder unit 34 detects sync (synchronization signal), for example, decodes the RLL code with reference to the synchronization detection position (channel decoding = encoding decoding), and outputs the original data string obtained as a result.

  Next, a detailed configuration example of the PLL unit 31 will be described with reference to FIG. That is, FIG. 11 shows a configuration example of the PLL unit 31 which is an embodiment of the phase synchronization apparatus to which the method of the present invention is applied. In the PLL unit 31 of FIG. 11, the same reference numerals are given to the parts corresponding to those of the conventional PLL unit of FIG. 3, and the description thereof is omitted as appropriate.

  In the example of FIG. 11, the PLL unit 31 is configured as a Digital ITR type PLL circuit. Therefore, in the example of FIG. 11, the PLL unit 5 includes an interpolation filter unit 11, a phase error information detection unit 41, a loop filter unit 13, and a remainder accumulation unit 14. That is, a PLL unit 31 that employs a phase error information detection unit 41 instead of the phase error information detection unit 12 in the conventional PLL unit of FIG. 3 is an embodiment of a phase synchronization apparatus to which the present invention is applied. It is a form.

  Therefore, only the phase error information detection unit 41 will be described below.

  In the example of FIG. 11, the phase error information detection unit 41 includes a slice unit 51 and a phase error detection unit 52.

  The slice unit 51 is configured to include a first slice unit 51-1 and a second slice unit 51-2.

  The first slice unit 51-1 is given an algorithm corresponding to PR (1, −1), and calculates slice_now corresponding to data_now supplied from the interpolation filter unit 11 according to this algorithm. Then, the first slice unit 51-1 supplies the slice_now to the phase error detection unit 52 and also supplies it to the switching determination control unit 32 as the switching determination index information described above.

  On the other hand, the second slice unit 51-2 is given an algorithm corresponding to PR (1, 0, -1), and corresponds to data_now supplied from the interpolation filter unit 11 according to this algorithm. Calculate slice_now. Then, the second slice unit 51-2 supplies the slice_now to the phase error detection unit 52 and also supplies it to the switching determination control unit 32 as the switching determination index information described above.

  Switching between the first slice unit 51-1 and the second slice unit 51-2 is performed by the switching determination information chg from the switching determination control unit 32.

  Note that the same slice unit 51 can be applied regardless of whether PR (1, -1) or PR (1,0, -1). However, from the viewpoint of maintaining performance, as in the example of FIG. 11, the first slice unit 51-1 used in PR (1, -1) and the PR (1,0, -1) are used. It is preferable to provide the second slice unit 51-2 and switch between them.

  In the example of FIG. 11, the phase error detection unit 52 is configured to include a first phase error detection unit 52-1 and a second phase error detection unit 52-2.

  The first phase error detector 52-1 is provided with an algorithm corresponding to PR (1, -1) (see, for example, the item of phase_err in FIG. 13 and FIG. 14 described later), and an interpolation filter according to this algorithm. The phase error information is calculated using the data_D and data_now supplied from the unit 11 and the slice_D and slice_now supplied from the slice unit 51 and provided to the loop filter unit 13.

  On the other hand, the second phase error detection unit 52-2 is given an algorithm corresponding to PR (1, 0, -1) (for example, refer to the item of phase_err in FIGS. 15 and 16 described later). In accordance with this algorithm, phase error information is calculated using data_D, data_now, etc. supplied from the interpolation filter unit 11 and slice_D, slice_now, etc. supplied from the slice unit 51, and provided to the loop filter unit 13.

  Switching between the first phase error detection unit 52-1 and the second phase error detection unit 52-2 is performed by the switching determination information chg from the switching determination control unit 32.

  As described above, with reference to FIG. 10 and FIG. 11, the configuration of an embodiment of a data reproducing apparatus to which the present invention is applied or a data reproducing apparatus including a PLL unit as a phase synchronization apparatus to which the present invention is applied. An example was described.

  The data reproducing process of the data reproducing apparatus having the configuration shown in FIG. 10 is basically executed according to the flowchart shown in FIG. Therefore, the description of the data reproduction process is omitted here.

  However, assuming that each sampling value constituting the synchronization data is one unit, the processing of one unit of the PLL unit 31 and the PRML unit 33, that is, the processing of steps S5 and S6 in FIG. Thus, the processing corresponds to one of PR (1, -1) and PR (1, 0, -1). As described above, the switching determination control unit 32 controls which of PR (1, -1) and PR (1, 0, -1) corresponds to the processing. Hereinafter, the operation of the switching determination control unit 32 will be described with reference to FIGS. 12 to 16.

  FIG. 12 is a flowchart illustrating an example of processing of the switching determination control unit 32 (hereinafter referred to as switching determination processing). Therefore, an example of the switching determination process will be described below with reference to the flowchart of FIG.

  In step S21, the switching determination control unit 32 calculates slice_now output immediately before from the PLL unit 31 (more precisely, the first slice unit 51-1 or the second slice unit 51-2 in FIG. 11). Acquired as switching determination index information.

  In step S22, the switching determination control unit 32 determines the transition pattern of the slice value including slice_now. That is, in step S22, for example, a combination of slice_D and slice_now (slice_D, slice_now) is determined as a transition pattern. Further, for example, as will be described later, a slice value (hereinafter referred to as slice_2D) two slices before slice_now is added, and a combination of slice_2D, slice_D, and slice_now (slice_2D, slice_D, slice_now) It may be determined as a transition pattern.

  In step S23, the switching determination control unit 32 determines whether or not the transition pattern determined in the process of step S22 is a switching pattern. The switching pattern is a transition pattern that exists in the back phase state in the currently used partial response method and cannot exist in the normal ideal state. A specific example of this switching pattern will be described later with reference to FIGS.

  If it is determined in step S23 that the pattern is a switching pattern, the switching determination control unit 32 outputs switching determination information chg = 1 in step S24.

  That is, in the example of FIG. 12, the switching determination information chg is a flag, and when the flag is set (when the switching determination information chg = 1), the PLL unit 31 and the PRML unit 33 use the partial response method currently Switch from the method you are using to another method.

  Specifically, for example, the first PRML unit 33-1, the first slice unit 51-1, and the first phase error detection unit 52-1 corresponding to PR (1, -1) are used. When the switching determination information chg = 1 is output from the switching determination control unit 32 in the process of step S24, the second PRML unit 33-2 corresponding to PR (1,0, -1), the second Switching is performed so that the slice unit 51-2 and the second phase error detection unit 52-2 are used.

  In addition, for example, the second PRML unit 33-2, the second slice unit 51-2, and the second phase error detection unit 52-2 corresponding to PR (1,0, -1) are used. In the state, when the switching determination information chg = 1 is output from the switching determination control unit 32 in the process of step S24, the first PRML unit 33-1 and the first slice unit 51 corresponding to PR (1, -1). −1 and the first phase error detector 52-1 are switched.

  On the other hand, if it is determined in step S23 that it is not a switching pattern, in step S25, the switching determination control unit 32 outputs switching determination information chg = 0.

  That is, in the example of FIG. 12, the switching determination information chg is a flag as described above, and when the flag is cleared (when the switching determination information chg = 0), the PLL unit 31 and the PRML unit 33 are , Use as it is without switching the partial response method.

  Specifically, for example, the first PRML unit 33-1, the first slice unit 51-1, and the first phase error detection unit 52-1 corresponding to PR (1, -1) are used. When the switching determination information chg = 0 is output from the switching determination control unit 32 in the process of step S25, the first PRML unit 33-1, the first slice unit 51-1, and the first phase The error detection unit 52-1 is used as it is.

  In addition, for example, the second PRML unit 33-2, the second slice unit 51-2, and the second phase error detection unit 52-2 corresponding to PR (1,0, -1) are used. In the state, when the switching determination information chg = 0 is output from the switching determination control unit 32 in the process of step S25, the second PRML unit 33-2 corresponding to PR (1,0, -1), the second slice The unit 51-2 and the second phase error detection unit 52-2 are used as they are.

  In step S26, the switching determination control unit 32 sets slice_now so far to slice_D. In some cases, the previous slice_D is further set to slice_2D in the process of step S26.

  In step S <b> 27, the switching determination control unit 32 determines whether or not the next slice_now is output from the PLL unit 31.

  That is, as long as the output of the synchronous sampling data from the PLL unit 31 continues and as a result, slice_now continues to be supplied from the PLL unit 31 to the switching determination control unit 32 as switching determination index information, it is determined as NO in step S27. Then, the process returns to step S21, and the loop process of steps S21 to S27 described above is repeatedly executed.

  Then, when the output of the synchronous sampling data from the PLL unit 11 ends, and as a result, the output of slice_now from the PLL unit 31 also ends, it is determined as YES in step S27, and the switching determination process ends.

  In the above-described example, for simplification of description, if the transition pattern of the slice value becomes a switching pattern even once, it is determined YES in the process of step S23, and the switching determination information chg = 1 in the process of step S24. Is output. However, in this case, there arises a problem that it is determined to be YES in the process of step S23 when switching should not be performed due to erroneous determination of the transition pattern.

  Therefore, in order to prevent the occurrence of such a problem (to solve the problem), the process of step S23 is performed only when the transition pattern of the slice value serving as the switching pattern occurs not only once but many times. What is necessary is just to make it determine with it being a switching pattern. Actually, when the number of switching patterns among a plurality of slice value transition patterns, which are the processing results of a plurality of times in step S22 in the past, exceeds a predetermined threshold value, the switching pattern is processed in step S23. What is necessary is just to make it determine.

  In other words, when the number of transition patterns of the slice value serving as the switching pattern is equal to or greater than the threshold, the flag that is the switching determination information chg is set up, that is, the switching determination information chg = 1 is output. What is necessary is just to weight with respect to a flag.

  Next, a specific example of the switching pattern described above will be described with reference to FIGS.

  13 shows the operation (algorithm) of the switching determination control unit 32 in FIG. 10 and the operation (algorithm) of the phase error information detection unit 41 in FIG. 11, where d = 1 and PR (1, −1 FIG. 3 is a diagram for explaining an algorithm in equalization.

  As a precondition in FIG. 13, whether or not to appear is an item indicating whether or not the pattern (slice_D, slice_now) shown on the left side is present at the normal time (normally ideal time) when there is no error. . That is, in the item of whether to appear or not, the pattern of (slice_D, slice_now) shown on the left side with （(double circle) is a pattern that can occur at normal time without error. On the other hand, the pattern of (slice_D, slice_now) shown on the left side with x (X) in the presence / absence of appearance is a pattern that cannot occur at normal time without error, and is the example of FIG. Then, it is a pattern in the back phase. Note that the reverse phase is described as (pha) on the right side of x (cross).

  Further, as a prerequisite of FIG. 13, whether correction is possible or not is an item indicating whether or not phase correction by phase_err (described below) can be performed when there is no error. That is, in the correction availability item, in the pattern (slice_D, slice_now) shown on the left side with ◎ (double circle), phase correction by phase_err can be performed when there is no error. On the other hand, when correction is possible, in the pattern (slice_D, slice_now) shown on the left side with-(bar mark), phase correction by phase_err cannot be performed when there is no error.

  As a prerequisite of FIG. 13, phase_err is an item indicating phase error information (a calculation method thereof) calculated by the phase error detection unit 52 of FIG. 11. The phase_err indicates the above-described expression (4) (expression shown in the lower part of FIG. 13) itself.

  Furthermore, as a precondition of FIG. 13, switching determination refers to the partial response method currently used (PR (1,1) in the example of FIG. 13) to another partial response method (in the example of FIG. 13). PR (1,0, -1)) is an item indicating a determination result of whether or not to switch. That is, in the item of switching determination, in the case of the pattern (slice_D, slice_now) shown on the left side with ◎ (double circle mark), it is determined to switch. That is, it is determined that it is a switching pattern (YES) in the process of step S23 of FIG. On the other hand, in the item of switching determination, in the case of the pattern (slice_D, slice_now) shown on the left side with-(bar mark), it is determined that switching is not performed. That is, it is determined in step S23 that the pattern is not a switching pattern (NO).

  Alternatively, as described above, when the flag that is the switching determination information chg is weighted, that is, when the switching is performed for the first time after the switching pattern is generated a plurality of times, whether or not the switching determination process becomes active That is, it can be said that the item indicating whether or not to start the switching determination process itself is the switching determination. In this case, ◎ (double circle) indicates that it is active, that is, the switching determination process is started. However, in the following, for simplification of explanation, in the case of a pattern with ◎ (double circle), switching is performed immediately, and in the case of a pattern with-(bar), switching is performed. Suppose you don't.

  These assumptions in FIG. 13 are similarly assumed in FIGS. 14 to 16 described later.

  Here, when d = 1 and the process is being executed according to the algorithm in PR (1, -1) equalization, that is, the first PRML unit 33-corresponding to PR (1, -1) Consider a case where the first slice unit 51-1 and the first phase error detection unit 52-1 are used.

  In this case, (slice_D, slice_now) determined in the process of step S22 in FIG. 12 is (1,1) as the item of switching determination in FIG. ), (-1, 1), (1, -1), or (-1, -1), it is determined in step S23 that the pattern is a switching pattern. The switching determination information chg = 1 is output in the process. Then, as described above, the second PRML unit 33-2, the second slice unit 51-2, and the second phase error detection unit 52-2 corresponding to PR (1,0, -1) Switch to be used.

  On the other hand, (slice_D, slice_now) determined in the process of step S22 in FIG. 12 is (0,1) as the item of switching determination in FIG. ), (0, -1), (1,0), (-1,0), it is determined in step S23 that it is not a switching pattern, and in step S25. The switching determination information chg = 0 is output. Then, as described above, the first PRML unit 33-1, the first slice unit 51-1, and the first phase error detection unit 52-1 are used as they are. At this time, the first phase error detection unit 52-1 calculates the phase error information according to the above-described equation (4) as shown in the item of phase_err in FIG.

  By the way, if (slice_D, slice_now) is (0,1), (0, -1), (1,0), (-1,0), considering slice_2D, PR (1, -1) There is also a pattern in the back phase state. In addition, if (slice_D, slice_now) is taken into consideration in (1,1), (-1,1), (1, -1), (-1, -1) up to slice_2D, PR (1,- It is not a pattern in the back phase state for 1), but a pattern that occurs due to an error or the like regardless of the phase position of data_now or data_D (a pattern that cannot normally occur in an ideal time. Also exists).

  Therefore, in order to perform more precise switching, it is preferable to adopt (slice_2D, slice_D, slice_now) as a transition pattern of slice values rather than simply adopt (slice_D, slice_now). An example of an algorithm that employs such (slice_2D, slice_D, slice_now) is shown in FIG. 14 shows the operation (algorithm) of the switching determination control unit 32 in FIG. 10 and the operation (algorithm) of the phase error information detection unit 41 in FIG. 11, where d = 1 and PR (1, -1) It is a figure explaining the other example of the algorithm in equalization.

  Here, as in the example of FIG. 13, when d = 1 and processing is currently being executed according to the algorithm in PR (1, -1) equalization, that is, it corresponds to PR (1, -1). Consider a case where the first PRML unit 33-1, the first slice unit 51-1, and the first phase error detection unit 52-1 are used.

  In this case, in the example of FIG. 14, the switching determination item is determined by the process of step S <b> 22 of FIG. 12 (slice_2D, slice_D, slice_now) as shown in the column (row) of 印 (double circle). Are (1,1,0), (-1, -1,0), (0,1,1), (-1,1,1), (-1, -1,1), (1,1 , -1), (0, -1, -1), (1, -1, -1), it is determined in step S23 that the pattern is a switching pattern, and switching determination information chg is determined in step S24. = 1 is output. Then, as described above, the second PRML unit 33-2, the second slice unit 51-2, and the second phase error detection unit 52-2 corresponding to PR (1,0, -1) Switch to be used.

  On the other hand, (slice_2D, slice_D, slice_now) determined in the process of step S22 in FIG. 12 is (α) as shown in the column (row) of − (bar mark) in FIG. , 0,0), (α, 0,1), (α, 0, -1), (0,1,0), (-1,1,0), (0, -1,0), ( 1, -1,0), (1,1,1), (0, -1,1), (1, -1,1), (0,1, -1), (-1,1,- 1), (-1, -1, -1) (where α is any value of -1,0,1), the switching pattern is processed in step S23. Therefore, the switching determination information chg = 0 is output in the process of step S25. Then, as described above, the first PRML unit 33-1, the first slice unit 51-1, and the first phase error detection unit 52-1 are used as they are. At this time, the first phase error detection unit 52-1 has (α, 0,1), (α, 0, -1), (0,1,0) as shown in the item of phase_err in FIG. ), (-1,1,0), (0, -1,0), (1, -1,0), the phase error information is calculated according to the above-described equation (4). On the other hand, the first phase error detector 52-1 includes (1,1,1), (0, -1,1), (1, -1,1), (0,1, -1), ( Since -1,1, -1) and (-1, -1, -1) are special patterns, 0 is output as phase error information.

  Note that (slice_2D, slice_D, slice_now) = (-1,1,0), (1, -1,0) is a special pattern as shown in the item of whether to appear. However, (-1,1,0) and (1, -1,0) are patterns in which the phase error information output direction at the time of error is probabilistically high in the forward direction. Therefore, for such a special pattern, phase_err calculated by the above equation (4) is output instead of 0 as phase error information.

  Heretofore, an example of an algorithm in d = 1 and PR (1, -1) equalization has been described.

  Next, an example of an algorithm in d = 1 and PR (1,0, -1) equalization will be described with reference to FIGS.

  15 and FIG. 16 show the operation (algorithm) of the switching determination control unit 32 in FIG. 10 and the operation (algorithm) of the phase error information detection unit 41 in FIG. 11, where d = 1 and PR It is a figure explaining the other example of the algorithm in (1,0, -1) equalization.

  Here, when d = 1 and the process is being executed according to the algorithm in PR (1,0, -1) equalization, that is, the second corresponding to PR (1,0, -1) Consider a case where the PRML unit 33-2, the second slice unit 51-2, and the second phase error detection unit 52-2 are used.

  In this case, in the example of FIG. 15 and FIG. 16, the item of the switching determination is determined by the process of step S22 of FIG. 12 (slice_2D, slice_D) as indicated by the ◎ (double circle) column (row). , Slice_now) is any one of (0,1,0) and (0, -1,0), it is determined in step S23 that the pattern is a switching pattern, and switching is performed in step S24. Determination information chg = 1 is output. Then, as described above, the first PRML unit 33-1, the first slice unit 51-1, and the first phase error detection unit 52-1 corresponding to PR (1, -1) are used. Can be switched.

  On the other hand, in the examples of FIGS. 15 and 16, the item of switching determination in FIG. 13 is determined in the process of step S <b> 22 in FIG. 12 as indicated in the column (row) of − (bar mark) ( If slice_D, slice_now) is other than (0,1,0), (0, -1,0), it is determined in step S23 that the pattern is not a switching pattern, and switching determination information chg in step S25. = 0 is output. Then, as described above, the second PRML unit 33-2, the second slice unit 51-2, and the second phase error detection unit 52-2 are used as they are.

  15 and FIG. 16 are compared, the operation of the second phase error detector 52-2 differs between the example of FIG. 15 and the example of FIG.

  That is, in the example of FIG. 15, (slice_2D, slice_D, slice_now) is (α, 1,1), (α, -1,1), (α, 1, -1), (α, -1, -1). ) (Where α is any value of -1,1,0), the second phase error detector 52-2 is shown in the phase_err item. In addition, phase_err calculated according to the above-described equation (4) is output as phase error information. On the other hand, (slice_2D, slice_D, slice_now) is one of (α, 0, 1), (α, 0, -1), (α, 1,0), (α, -1,0). In this case, the second phase error detector 52-2 outputs 0 as the phase error information as indicated by the item of phase_err.

  On the other hand, in the example of FIG. 16, (slice_2D, slice_D, slice_now) is (0,1,1), (-1,1,1), (0, -1,1), (-1,- 1,1), (0,1, -1), (1,1, -1), (0, -1, -1), (1, -1, -1) The phase error detection unit 52-2 outputs the phase_err calculated according to the above-described equation (4) as phase error information as indicated by the item of phase_err (the forward phase_err indicates the phase_err itself). become.

  Note that (slice_2D, slice_D, slice_now) = (0, -1,1), (0,1, -1) are special patterns for PR (-1,0,1), but “phase error information In order to realize “output without sample in the wrong direction and for each sample as much as possible”, (slice_2D, slice_D, slice_now) = (0, -1,1), (0,1,- In the case of 1), the forward direction phase_err is output as the phase error information.

  In the example of FIG. 16, (slice_2D, slice_D, slice_now) is (α, 0,0), (α, 0,1), (α, 0, -1), (α, 1,0), ( α, -1,0), (1,1,1), (1, -1,1), (-1,1, -1), (-1, -1, -1) The second phase error detection unit 52-2 outputs 0 as the phase error information as indicated by the phase_err item.

  The algorithm (operation) of the switching determination control unit 32 and the phase error information detection unit 41 has been described above with reference to FIGS. 13 to 16.

  By such an algorithm, the switching determination control unit 32 can switch the partial response method in an unstable state, so that the system (for example, the data reproducing apparatus in the example of FIG. 10) can have a more stable configuration. become.

  Note that this algorithm is not particularly limited to the above-described example, and may be an algorithm in which algorithm conditions are partially changed, that is, an algorithm in which, for example, the slice_D section is further increased as long as the rules described above are followed. Also in this case, the effect that the system (for example, the data reproducing apparatus in the example of FIG. 10) can be configured more stably can be achieved in exactly the same manner.

  As described above, the switching determination information chg is output from the switching determination control unit 32 by such an algorithm. The switching target in which the partial response method is switched by this switching determination information chg is, in the example of FIG. The PLL unit 31 and the PRML unit 33 are provided.

  However, in order to further stabilize the performance, as shown in FIG. 17, the EQ unit 3 and the AGC / DCC unit 4 in the preceding stage of the PLL unit 31 may be added to the switching target. That is, FIG. 17 shows a configuration example of an embodiment different from the example of FIG. 10 of the data reproducing apparatus to which the present invention is applied. In the data reproducing apparatus in the example of FIG. 17, the same reference numerals are given to the portions corresponding to those in the example of the data reproducing apparatus in FIG.

  In the example of FIG. 17, the switching determination information chg from the switching determination control unit 32 is provided to the EQ unit 3 and the AGC / DCC unit 4 in addition to the PLL unit 31 and the PRML unit 33.

  In the example of FIG. 17, the EQ unit 3 includes a first EQ unit 3-1 for PR (1, -1), and a second EQ unit 3-2 for PR (1,0, -1). It is comprised so that it may contain. That is, the first EQ unit 3-1 is an EQ unit in which each tap is set to be an equalization point more suitable for PR (1, -1). Similarly, the second EQ unit 3-2 is an EQ unit in which each tap is set to be an equalization point more suitable for PR (1,0, -1). Switching between the first EQ unit 3-1 and the second EQ unit 3-2 is performed based on the switching determination information chg. In other words, based on the switching determination information chg, the setting for PR (1, -1) (= setting of the first EQ unit 3-1) and the setting for PR (1,0, -1) (= It can be said that the setting of the second EQ unit 3-2 is switched.

  In the example of FIG. 17, the AGC / DCC unit 4 includes a first AGC / DCC unit 4-1 for PR (1, -1) and a second AGC / DCC for PR (1,0, -1). The DCC unit 4-2 is included. That is, the first AGC / DCC unit 4-1 is an AGC / DCC unit in which a gain or the like more suitable for PR (1, -1) is set. Similarly, the second AGC / DCC unit 4-2 is an AGC / DCC unit in which a gain or the like more suitable for PR (1,0, -1) is set.

  In other words, based on the switching determination information chg, the setting for PR (1, -1) (= setting of the first AGC / DCC unit 4-1) and the setting for PR (1,0, -1) (= Setting of the second AGC / DCC unit 4-2) can be said to be switched. Specifically, for example, comparing FIG. 4 and FIG. 5, the sample position in FIG. 4 is 1.0, whereas the sample position in FIG. 5 is around 0.67. Further, as is apparent from a comparison between FIG. 6 and FIG. 7, the identification points are closer to 0 to 0.67 in FIG. 7 than 0 to 1 in FIG. Therefore, paying attention to this point, in the AGC / DCC unit 4, for example, settings are made such that the gain of PR (1,0, -1) is larger than that of PR (1, -1). Just do it. Then, these settings may be switched based on the switching determination information chg.

  Heretofore, the configuration example of the data reproducing apparatus in the example of FIG. 17 has been described. The operation of the data reproducing apparatus in the example of FIG. 17 is basically the same as that of FIG. That is, the data reproduction processing of the data reproduction apparatus in the example of FIG. 17 is basically executed according to the flowchart of FIG. Therefore, the description of the data reproduction process is omitted here.

  Therefore, the operation of the switching determination control unit 32 in the example of FIG. 17 is basically the same as that of FIG. That is, the switching determination process of the switching determination control unit 32 in the example of FIG. 17 is basically executed according to the flowchart of FIG.

  However, the switching determination information chg output in the process of step S24 or S25 is provided to the EQ unit 3 and the AGC / DCC unit 4 in addition to the PLL unit 31 and the PRML unit 33 as described above.

  Specifically, for example, a first EQ unit 3-1, a first AGC / DCC unit 4-1, a first PRML unit 33-1 and a first slice unit corresponding to PR (1, -1) When the switching determination information chg = 1 is output from the switching determination control unit 32 in the process of step S24 in a state where the 51-1 and the first phase error detection unit 52-1 are used, PR (1, 0, -1) corresponding to the second EQ section 3-2, the second AGC / DCC section 4-2, the second PRML section 33-2, the second slice section 51-2, and the second The phase error detection unit 52-2 is switched to be used.

  Also, for example, the second EQ unit 3-2, the second AGC / DCC unit 4-2, the second PRML unit 33-2, and the second slice unit 51 corresponding to PR (1,0, -1). -2 and when the switching determination information chg = 1 is output from the switching determination control unit 32 in the process of step S24 in a state where the second phase error detection unit 52-2 is used, PR (1,- The first EQ unit 3-1, the first AGC / DCC unit 4-1, the first PRML unit 33-1, the first slice unit 51-1, and the first phase error corresponding to 1) It switches so that the detection part 52-1 may be utilized.

  On the other hand, for example, the first EQ unit 3-1, the first AGC / DCC unit 4-1, the first PRML unit 33-1 and the first slice unit corresponding to PR (1, -1). When the switching determination information chg = 0 is output from the switching determination control unit 32 in the process of step S25 in a state where the 51-1 and the first phase error detection unit 52-1 are used, the first EQ is output. Unit 3-1, first AGC / DCC unit 4-1, first PRML unit 33-1, first slice unit 51-1, and first phase error detection unit 52-1 are used as they are. The

  Also, for example, the second EQ unit 3-2, the second AGC / DCC unit 4-2, the second PRML unit 33-2, and the second slice unit 51 corresponding to PR (1,0, -1). -2, and when the switching determination information chg = 0 is output from the switching determination control unit 32 in the process of step S25 in a state where the second phase error detection unit 52-2 is used, PR (1,0 , -1) corresponding to the second EQ unit 3-2, the second AGC / DCC unit 4-2, the second PRML unit 33-2, the second slice unit 51-2, and the second The phase error detector 52-2 is used as it is.

  By the way, the switching determination index information used by the switching determination control unit 32 is the slice value from the PLL unit 31 in the above-described example. That is, the switching determination control unit 32 determines switching determination (whether the switching determination information chg is 1 or 0) according to an algorithm (for example, FIGS. 13 to 16 described above) using a slice value transition pattern. I was going.

  In addition, the switching determination control unit 32 may monitor an abnormal state such as a sync failure in the subsequent sync detection / decoder unit 34 and may determine switching based on the monitoring result. In this case, the data reproducing apparatus is configured as shown in FIG. 18, for example. That is, FIG. 18 shows a configuration example of an embodiment different from the example of FIG. 10 of the data reproducing apparatus to which the present invention is applied. In the data reproducing apparatus in the example of FIG. 18, the same reference numerals are given to the portions corresponding to those in the example of the data reproducing apparatus in FIG.

  In the example of FIG. 18, the switching determination index information is provided from the sync detection / decoding unit 34 to the switching determination control unit 32 instead of from the PLL unit 31.

  Therefore, the configuration of the PLL unit 31 is as shown in FIG. 19, for example. That is, FIG. 19 illustrates a configuration example of an embodiment of the PLL unit 31 different from the example of FIG. Compared with FIG. 11 and FIG. 19, the PLL unit 31 in the example of FIG. 19 is different from that in the example of FIG. 11 in that the slice value output from the slice unit 51 is the switching determination control unit. It is only a configuration that is not provided to 32. That is, other configurations are exactly the same as those in FIG. 11, and the description thereof is omitted as appropriate.

  Returning to FIG. 18, as the switching determination index information provided from the sync detection / decoding unit 34 to the switching determination control unit 32, for example, sync detection information such as a sync pattern error can be employed. In this case, although not shown, the switching determination process of the switching determination control unit 32 is as follows.

  That is, for example, the switching determination control unit 32 determines whether or not a sync pattern error has been detected a predetermined number of times or more. The switching determination control unit 32 outputs the switching determination information chg = 1 when it is determined that the sync pattern error has been detected a predetermined number of times or more, and outputs the switching determination information = 0 otherwise.

  The sync pattern error referred to here is an error having a feature that the detection of the sync pattern becomes significantly unstable in the state where the phase position is shifted by a predetermined amount or more (back phase state) than in the normal ideal time. Therefore, the switching determination control unit 32 does not need to use pull-in data or a specific identification signal pattern for the determination. That is, no individual pattern is given as the signal format.

  As this determination control, it is preferable to give a predetermined number of times in consideration of the fact that the actual data is a signal with disturbance.

  In addition, the sync detection / decoder unit 34 may extract information on cases different from the normal ideal time other than those described above, and provide this information to the switching determination control unit 32 as switching determination index information. Also in this case, the switching determination control unit 32 can execute a similar switching determination process. Specifically, for example, the switching determination control unit 32 refers to the ID bit accompanying the sync pattern as the switching determination index information, and if it is significantly different from the format, it is determined that the error is an error. Switching determination processing can be executed.

  More generally speaking, the switching determination index information used by the switching determination control unit 32 is not limited to the above-described slice value from the PLL unit 31 or the sync pattern error from the switching determination control unit 32, and is usually ideal. It may be information indicating a case different from the time.

  The configuration of the data reproducing apparatus in the example of FIG. 18 has been described above. The operation of the data reproducing apparatus in the example of FIG. 18 is basically the same as that of FIG. That is, the data reproduction processing of the data reproducing apparatus in the example of FIG. 18 is basically executed according to the flowchart of FIG. Therefore, the description of the data reproduction process is omitted here.

  By the way, the embodiment of the data reproducing apparatus that uses the information from the sync detection / decoder unit 34 as the switching determination index information is not limited to the example of FIG. For example, FIG. 20 shows a configuration example of an embodiment of a data reproduction apparatus corresponding to the above-described example of FIG. 17 among the data reproduction apparatuses that use information from the sync detection / decoder unit 34 as switching determination index information. It is shown. That is, FIG. 20 shows a configuration example of an embodiment different from the examples of FIGS. 17 and 18 of the data reproducing apparatus to which the present invention is applied. In the data reproducing apparatus in the example of FIG. 20, the same reference numerals are given to portions corresponding to those in the examples of the data reproducing apparatus in FIG. 17 and FIG.

  Also in the example of FIG. 20, the switching determination index information is provided from the sync detection / decoding unit 34 to the switching determination control unit 32 instead of the PLL unit 31. Therefore, the configuration of the PLL unit 31 in this case is also as shown in FIG. 19, for example. The rest of the configuration is basically the same as the corresponding configuration in the example of FIG.

  By the way, in the method of the present invention, that is, in the combination of partial response methods that are in reverse phase with each other, if a reverse phase state occurs during the process corresponding to one, it is switched to the process corresponding to the other. The method is not limited to the combination of PR (1, -1) and PR (1,0, -1).

  Further, for example, the technique of the present invention is not only applied to the PLL unit 31 having the slice unit 51 shown in FIG. 11 and the like, but also to the PLL unit having a slice unit that outputs a provisional determination value. The same can be applied.

  Further, for example, the method of the present invention changes not only the PLL unit 31 in the example of FIG. 11 and the like described above but also changes the sampling frequency and phase of the A / D conversion unit without using the interpolation filter unit, for example. The same can be applied to a PLL section using a VCO (Voltage Controlled Oscillator). An example of an embodiment of a data reproducing apparatus having a PLL unit using such a VCO is shown in FIG. 21 and FIG. That is, FIG. 21 and FIG. 22 show configuration examples of embodiments different from the above-described various examples of the data reproducing apparatus to which the present invention is applied. Specifically, FIG. 21 illustrates a configuration example of the embodiment in the case where the switching determination index information is supplied from the PLL unit 61 to the switching determination control unit 32. On the other hand, FIG. 22 shows a configuration example of the embodiment when the switching determination index information is supplied from the sync detection / decoding unit 34 to the switching determination control unit 32.

  21 and FIG. 22, the PLL unit 61 includes an analog equalization unit 71, an A / D conversion unit 72, a phase error information detection unit 41, a loop filter unit 73, a D / A conversion unit 74, and a VCO unit. 75.

  The analog equalization unit 71 generates an analog signal shaped to be equal to a predetermined PR method from the reproduced RF signal, and supplies the analog signal to the A / D conversion unit 72.

  The A / D conversion unit 72 generates digital synchronous sampling data by synchronously sampling the analog signal from the analog equalization unit 71 so as to synchronize with the frequency of the VCO output signal from the VCO unit 75, and outputs it. To do.

  The synchronous sampling data from the A / D converter 72 is also supplied to the phase error information detector 41. This phase error information detection unit 41 is also employed in the PLL unit 31 in the example of FIG. 11 described above. Therefore, the description of the phase error information detection unit 41 is omitted.

  The loop filter unit 73 performs a loop filter operation using a predetermined loop filter coefficient and a predetermined initial value as necessary in addition to the phase error information supplied from the phase error information detection unit 41, The calculation result is provided to the D / A converter 74.

  The D / A conversion unit 74 converts the digital signal that is the loop filter calculation result of the loop filter unit 73 into an analog signal, and provides the analog signal to the VCO unit 75 as a VCO input signal.

  The VCO unit 75 generates a VCO output signal corresponding to the voltage level of the VCO input signal from the D / A conversion unit 74 and provides it to the A / D conversion unit 72 and the like.

  Thus, the technique of the present invention can be applied to various PLLs such as the PLL unit 31 such as the example of FIG. 11 and the PLL unit 61 such as the example of FIG. In other words, a PLL to which the method of the present invention is applied is realized by adopting the phase error information detection unit 41 such as the examples of FIGS. 11 and 21 instead of the conventional phase error information detection unit 12 of FIG. It becomes possible easily.

  Furthermore, the PLL to which the present invention is applied can be applied not only to the data reproduction apparatus of FIG. 1 but also easily to various apparatuses and systems (the system will be described later).

  Further, for example, the technique of the present invention generates a predetermined filter unit that generates an analog signal that can be adapted to a predetermined PR equalization from the reproduced RF signal, instead of the differential filter unit 1 of FIG. The present invention can also be applied to a data reproducing apparatus employing the above.

  Further, for example, the technique of the present invention is applied to a data reproducing apparatus in which a data detection unit capable of detecting an RLL code from synchronous sampling data from the PLL unit 31 is used instead of the PRML unit 33 in FIG. Is also applicable.

  Further, for example, the switching determination information chg of the switching determination control unit 32 in FIG. 10 and the like is used for switching of the partial response system such as the PLL unit 31 and the PRML unit 33 in the above-described example. It can also be used to clear the data remaining in each block at the time when is output or set it to a predetermined value. As a result, the entire data reproducing apparatus can be configured to be further stabilized.

  By the way, as a further application technique of the technique of the present invention, it is possible to easily realize a technique for more effectively dealing with reproduction of a plurality of recording densities.

  For example, as a system in which the recording density is switched according to the input data, at the time of high density, the initial value is started by switching to a PR system (for example, PR (1,0, -1)) suitable for higher density. Switching control gives a setting that makes it difficult to switch to PR (1, -1). On the other hand, when the density is not high, the initial value is started by switching to PR (1, -1), for example. As a result, it is possible to avoid an error state caused by locking in the back phase state in principle, and as a result, a stable system can be realized.

  As a system to which this applied technique is applied, for example, it can be realized as a data reproducing apparatus basically similar to the configuration of FIG. 10 or FIG. However, in this case, although not shown, for example, there are two outputs from the sync detection / decoder unit 34 to the switching determination control unit 32. That is, in addition to the output of the switching determination index information necessary for generating the switching determination information chg described above, output of information indicating which of the recording densities embedded in a predetermined format in the format is selected Is required. This latter information is used for the initial value setting of the switching determination control unit 32 and the setting of switching control.

  By the way, this latter information may be information from a detection unit (not shown) other than from the sync detection / decoder unit 34, and so on.

  In this applied method, identification information is held in, for example, a header portion in a data format, and is used to switch between an operation clock and a rotation speed for recording and reproduction, for example. The identification information is used as the initial value of the switching determination control unit 32. However, in the subsequent operation, the individual information described above (such as a 4T continuous pull-in pattern) is not necessary for switching determination.

  By the way, the above-described series of processes (or a part of them) can be executed by hardware, but can also be executed by software.

  In this case, the whole or a part of the data reproducing apparatus shown in FIGS. 1, 10, 17, 18, 20, 21, and 22 (for example, the PLL unit 31) is, for example, a computer shown in FIG. Can be configured.

  23, a CPU (Central Processing Unit) 101 executes various processes according to a program recorded in a ROM (Read Only Memory) 102 or a program loaded from a storage unit 108 to a RAM (Random Access Memory) 103. To do. The RAM 103 also appropriately stores data necessary for the CPU 101 to execute various processes.

  The CPU 101, ROM 102, and RAM 103 are connected to each other via a bus 104. An input / output interface 105 is also connected to the bus 104.

  The input / output interface 105 includes an input unit 106 such as a keyboard and a mouse, an output unit 107 composed of a display, a storage unit 108 composed of a hard disk, and a communication unit 109 composed of a modem and a terminal adapter. It is connected. The communication unit 109 performs communication processing with other devices (not shown) via a network including the Internet.

  A drive 110 is also connected to the input / output interface 105 as necessary, and a removable recording medium 111 made of a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is appropriately installed, and a computer program read from them is read. Are installed in the storage unit 108 as necessary.

  When a series of processing is executed by software, the program that constitutes the software executes a variety of functions by installing a computer embedded in dedicated hardware or various programs. It is installed from a network or a recording medium on a computer (for example, a general-purpose personal computer) that can perform the above-described operation.

  As shown in FIG. 23, a recording medium including such a program is distributed to provide a program to the user separately from the apparatus main body, and a magnetic disk (including a floppy disk) on which the program is recorded, Removable recording media (package media) consisting of optical disks (including compact disk-read only memory (CD-ROM), DVD (digital versatile disk)), magneto-optical disks (including MD (mini-disk)), or semiconductor memory ) 111 as well as a ROM 102 on which a program is recorded and a hard disk included in the storage unit 108 provided to the user in a state of being incorporated in the apparatus main body in advance.

  In the present specification, the step of describing the program recorded on the recording medium is not limited to the processing performed in time series along the order, but is not necessarily performed in time series, either in parallel or individually. The process to be executed is also included.

  Further, in this specification, the system represents the entire apparatus configured by a plurality of processing devices and a plurality of processing units.

It is a figure which shows the structural example of one Embodiment of the data reproduction apparatus to which this invention is applied. 3 is a flowchart for explaining an example of data reproduction processing of the data reproduction apparatus of FIG. 1. It is a figure which shows the structural example of the conventional Digital ITR type PLL. It is a model figure for demonstrating the state of a back phase. It is a model figure for demonstrating the state of a back phase. It is a model figure for demonstrating the state of a back phase. It is a model figure for demonstrating the state of a back phase. It is the figure of the response waveform which showed a mode that the conventional PLL of FIG. 3 locked. It is the figure of the response waveform which showed a mode that the conventional PLL of FIG. 3 locked to the back phase side. It is a figure which shows the structural example of other embodiment of the data reproducing device to which this invention is applied. FIG. 11 is a diagram showing a configuration example of an embodiment of a phase synchronization apparatus to which the present invention is applied, which is a PLL unit mounted in the data reproduction apparatus of FIG. 10. It is a flowchart explaining an example of the switching determination process of the switching determination control part of FIG. FIG. 12 is a diagram illustrating an example of an algorithm of a switching determination control unit in FIG. 10 and a phase error information detection unit in FIG. 11 when d = 1 and PR (1, −1) based on the present invention. FIG. 12 is a diagram illustrating another example of the algorithm of the switching determination control unit in FIG. 10 and the phase error information detection unit in FIG. 11 when d = 1 and PR (1, −1) based on the present invention. FIG. 12 is a diagram illustrating an example of algorithms of a switching determination control unit in FIG. 10 and a phase error information detection unit in FIG. 11 in d = 1 and PR (1,0, −1) equalization based on the present invention. FIG. 12 is a diagram showing another example of the algorithm of the switching determination control unit in FIG. 10 and the phase error information detection unit in FIG. 11 in d = 1 and PR (1,0, −1) equalization based on the present invention. It is a figure which shows the structural example of other embodiment of the data reproducing device to which this invention is applied. It is a figure which shows the structural example of other embodiment of the data reproducing device to which this invention is applied. FIG. 19 is a diagram illustrating a configuration example of an embodiment of a phase synchronization apparatus to which the present invention is applied, which is a PLL unit mounted in the data reproduction apparatus of FIG. 18. It is a figure which shows the structural example of other embodiment of the data reproducing device to which this invention is applied. It is a figure which shows the structural example of other embodiment of the data reproducing device to which this invention is applied. It is a figure which shows the structural example of other embodiment of the data reproducing device to which this invention is applied. It is a figure which shows the example of a structure about embodiment in which all or one part of the data reproduction apparatus and phase-synchronization apparatus to which this invention is applied comprised with the computer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Differential filter part, 2 A / D conversion part, 3 EQ part, 3-1 1st EQ part, 3-2 2nd EQ part, 4 AGC / DCC part, 4-1 1st AGC / DCC part 4-2, second AGC / DCC unit, 5 PLL unit, 6 PRML unit, 7 decoding unit, 11 interpolation filter unit, 13 loop filter unit, 14 remainder accumulation unit, 31 PLL unit, 32 switching determination control unit, 33 PRML section, 33-1 first PRML section, 33-2 second PRML section, 34 sync detection / decoding section, 41 phase error information detection section, 51 slice section, 51-1 first slice section, 51 -2 second slice unit, 52 phase error detection unit, 52-1 first phase error detection unit, 52-2 second phase error detection unit,

51 phase position determination unit, 52 phase error information calculation unit, 71 analog equalization unit, 72 A / D conversion unit, 73 loop filter unit, 74 D / A conversion unit, 75 VCO unit, 101 CPU, 102 ROM, 108 storage , 111 Removable recording media

Claims (29)

In a data reproduction device for reproducing data,
When data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the asynchronous data is read from the asynchronous data according to the first algorithm or the second algorithm. Phase synchronization means for generating synchronization data synchronized with a predetermined frequency;
A channel corresponding to the RLL recording code from the synchronization data generated by the phase synchronization means according to a third algorithm corresponding to the first algorithm or a fourth algorithm corresponding to the second algorithm Data detection means for detecting a bit string;
Decoding means for decoding the channel bit string detected by the data detection means;
Based on the data string that is generated, detected, or used by at least one of the phase synchronization means, the data detection means, and the decoding means, and does not have identification information individually, Switching determination means for determining a first switching between the first algorithm and the second algorithm, and a second switching between the third algorithm and the fourth algorithm, Data reproducing device. 2. The data reproducing apparatus according to claim 1, wherein the switching determination unit determines the first switching and the second switching based on the data string used by the phase synchronization unit. 3. . The phase synchronization means uses two or more sampling values in a predetermined section of the synchronization data and two or more temporary determination values for each of the two or more sampling values in the predetermined section. And phase error information detection means for detecting phase error information indicating a phase error of the synchronization data,
The switching determination unit determines the first switching and the second switching based on two or more provisional determination values used by the phase error information detection unit of the phase synchronization unit. The data reproducing apparatus according to claim 2. The first algorithm and the third algorithm are algorithms corresponding to a first partial response method, and the second algorithm and the fourth algorithm are algorithms corresponding to a second partial response method. Yes,
The switching determination means includes
The transition pattern of two or more provisional judgment values including at least two or more provisional judgment values used by the phase error information detection means is an ideal state in a partial response method corresponding to an algorithm currently used. Sometimes it is determined whether a specific pattern cannot exist,
If it is determined that the specific pattern, it is determined to perform the first switching and the second switching,
The data reproducing apparatus according to claim 3, wherein when it is determined that the pattern is not the specific pattern, it is determined that the first switching and the second switching are prohibited. The phase error information detection means includes
The sampling value to be processed in the synchronization data is data_now, the sampling value immediately before the data_now is data_D, the provisional determination value for data_now is slice_now, the provisional determination value for data_D is slice_D, and the phase error As information phase_err,
phase_err = (data_now * slice_D)-(data_D * slice_now)
The phase error information is detected according to a first calculation method using an arithmetic expression represented by:
Between the first partial response method and the second partial response method, there is a relationship in which phase_err of at least one of the methods is 0 for all combinations of slice_D and slice_now. The data reproducing apparatus according to claim 4. The phase error information detection means includes
When it is determined by the switching determination means that the pattern is not the specific pattern, the phase error information is detected according to the first calculation method,
6. The data reproducing apparatus according to claim 5, further comprising: detecting the phase error information according to a second calculation method when the switching determination unit determines that the specific pattern is used. The data reproducing apparatus according to claim 6, wherein the second calculation method is a calculation method of outputting 0 as the phase error information. The specific pattern is
Of the two or more sampling values used by the phase error information detection means, a phase position between a predetermined first value and a second value adjacent thereto is the first value and the second value. 5. The pattern generated in the case of a back phase state in which the phase position is a value when only one of the values exceeds a predetermined threshold value. 6. Data playback device. Between the first partial response method and the second partial response method, the phase positions of the first value and the second value are positions in an ideal state for either one of the methods. 9. The data reproducing apparatus according to claim 8, wherein there is a relationship that the position of the back phase state is obtained for the other method. D = 1 of the RLL recording code recorded on the recording medium,
The first partial response method is PR (1, -1),
The data reproducing apparatus according to claim 9, wherein the second partial response method is PR (1,0, -1). The sampling value to be processed of the synchronous data is set as data_now, the sampling value immediately before the data_now is set as data_D, the temporary determination value for data_now is set as slice_now, and the temporary determination value for data_D is set as slice_D
The switching determination unit determines whether a combination pattern of slice_D and slice_now is the specific pattern in PR (1, -1) or PR (1,0, -1) currently used. The data reproducing apparatus according to claim 10. The sampling value two times before data_now is data_2D, the provisional judgment value for data_2D is slice_2D,
The switching determination means further determines whether the combination pattern of slice_2D, slice_D, and slice_now is the specific pattern in the currently used PR (1, -1) or PR (1,0, -1) The data reproducing apparatus according to claim 11, wherein: The data reproduction apparatus according to claim 1, wherein the switching determination unit further generates switching determination information indicating the determination result. The phase synchronization means includes
First phase error information detecting means for detecting phase error information indicating a phase error of the synchronization data according to the first algorithm;
The second phase error information detecting means for detecting the phase error information according to the second algorithm,
When the switching determination information generated by the switching determination unit includes information that the first switching is performed, the first phase error information detection unit and the second phase error information detection unit Switch from one currently in use to the other,
When the switching determination information generated by the switching determination unit includes information indicating that the first switching is not performed, the first phase error information detection unit and the second phase error information detection unit 14. The data reproducing apparatus according to claim 13, wherein switching from one currently used to the other is prohibited. Each of the first phase error information detection means and the second phase error information detection means includes two or more sampling values in a predetermined section of the synchronization data, and two or more in the predetermined section. Using the two or more provisional determination values for each of the sampling values of, detecting the phase error information,
The phase synchronization means further includes
First temporary determination value calculating means for calculating the temporary determination value according to the first algorithm;
The second temporary determination value calculating means for calculating the temporary determination value according to the second algorithm;
When the switching determination information generated by the switching determination unit includes information indicating that the first switching is performed, further, the first temporary determination value calculation unit and the second temporary determination value calculation unit Of which one is currently being used and switched to the other,
When the switching determination information generated by the switching determination unit includes information that the first switching is not performed, the first temporary determination value calculation unit and the second temporary determination value calculation unit The data reproducing device according to claim 14, wherein switching from one currently used to the other is prohibited. When the switching determination information generated by the switching determination unit includes information that the first switching is performed, a predetermined setting value for the phase synchronization unit is further changed,
When the switching determination information generated by the switching determination unit includes information that the first switching is not performed, the change of the predetermined setting value with respect to the phase synchronization unit is further prohibited. The data reproducing apparatus according to claim 15. The data detection means includes
First data detecting means for detecting the channel bit string from the synchronization data according to the third algorithm;
Second data detection means for detecting the channel bit string from the synchronization data according to the fourth algorithm,
When the switching determination information generated by the switching determination unit includes information indicating that the second switching is performed, the switching determination information is currently used between the first data detection unit and the second data detection unit. Is switched from one to the other,
When the switching determination information generated by the switching determination unit includes information that the second switching is not performed, the current use of the first data detection unit and the second data detection unit 14. The data reproducing apparatus according to claim 13, wherein switching from one to the other is prohibited. The data reproduction device further includes a waveform shaping unit that shapes a predetermined waveform of the asynchronous data generated by the sampling unit, and outputs the asynchronous data after shaping,
The phase synchronization means generates the synchronization data from the asynchronous data output from the waveform shaping means,
When the switching determination information generated by the switching determination unit includes information that at least one of the first switching and the second switching is performed, a predetermined setting value for the waveform shaping unit is changed. And
When the switching determination information generated by the switching determination unit includes information indicating that neither the first switching nor the second switching is performed, the change of the predetermined setting value with respect to the waveform shaping unit is prohibited. The data reproducing device according to claim 13, wherein The data reproduction device further performs gain control (AGC: Auto Gain Control) and DC (Direct Current) offset cancellation (DCC: DC Cancel) of the asynchronous data output from the waveform shaping means, AGC / DCC means for outputting the asynchronous data,
The phase synchronization means generates the synchronization data from the asynchronous data output from the AGC / DCC means,
When the switching determination information generated by the switching determination unit includes information indicating that at least one of the first switching and the second switching is performed, a predetermined setting for the AGC / DCC unit is further provided. The value is changed,
When the switching determination information generated by the switching determination unit includes information indicating that neither the first switching nor the second switching is performed, the change of the predetermined setting value for the AGC / DCC unit is performed. 14. The data reproducing apparatus according to claim 13, wherein the data reproducing apparatus is prohibited. The switch determination information is a flag. When the flag is set, the first switch and the second switch are performed. When the flag is set, the first switch and the switch The data reproducing apparatus according to claim 13, wherein the second switching is not performed together. 21. The flag is weighted based on the predetermined condition so that the data string not individually having identification information satisfies the predetermined condition so that the flag is set. The data reproducing device described in 1. The predetermined condition is a condition that a pattern string that cannot ideally appear in the data string that does not have identification information individually is included in a predetermined amount or more. Data playback device. The data reproducing device further includes:
Differentiating means for generating a differential response signal of the analog signal when the data recorded on the predetermined recording medium as an RLL recording code of d> 0 is read from the predetermined recording medium as an analog signal; ,
Sampling means for generating the asynchronous data by sampling the analog differential response signal generated by the differentiating means asynchronously to the predetermined frequency, and
The data reproducing apparatus according to claim 1, wherein the phase synchronization means generates the synchronous data from the asynchronous data generated by the sampling means. The phase synchronization means includes
Phase error information detecting means for detecting phase error information indicating a phase error of the synchronization data according to the first algorithm or the second algorithm;
A loop filter means for performing a loop filter calculation using at least the phase error information detected by the phase error information detection means, and outputting the calculation result;
Performs a predetermined accumulation process on the calculation result output from the loop filter means, and generates information necessary for adjusting the phase position of each sampling value constituting the asynchronous data based on the process result The remainder accumulation means to output
Using the information output from the residue accumulation means, the phase position of each sampling value constituting the asynchronous data is adjusted, and the data constituted by the adjusted sampling values is used as the synchronization data. The data reproducing apparatus according to claim 1, further comprising: a phase adjusting unit that outputs the data. The data reproducing apparatus according to claim 1, wherein the switching determination unit determines the first switching and the second switching based on the data string detected by the decoding unit. 26. The data reproducing apparatus according to claim 25, wherein the data string detected by the decoding unit is predetermined information extracted from the channel bit string detected by the data detecting unit. The predetermined information extracted from the channel bit string is a SYNC included in the channel bit string in an ideal state,
The switching determination means determines that the first switching and the second switching are prohibited when the decoding means detects the SYNC, and when the decoding means does not detect the SYNC. 27. The data reproducing device according to claim 26, wherein it is determined that the first switching and the second switching are performed. In a data reproduction method of a data reproduction apparatus for reproducing data,
When data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the asynchronous data is read from the asynchronous data according to the first algorithm or the second algorithm. A phase synchronization step for generating synchronization data synchronized to a predetermined frequency;
A channel corresponding to the RLL recording code from the synchronization data generated by the phase synchronization means according to a third algorithm corresponding to the first algorithm or a fourth algorithm corresponding to the second algorithm A data detection step for detecting a bit string;
A decoding step of decoding the channel bit string detected by the processing of the data detection step;
Based on the data sequence that is generated, detected, or used by at least one of the phase synchronization step, the data detection step, and the decoding step and does not have identification information individually, And a switching determination step for determining a first switching between the first algorithm and the second algorithm and a second switching between the third algorithm and the fourth algorithm. Data playback method. A program to be executed by a computer that performs control for reproducing data,
When data recorded on a predetermined recording medium as an RLL recording code of d> 0 is read asynchronously at a predetermined frequency, the asynchronous data is read from the asynchronous data according to the first algorithm or the second algorithm. A phase synchronization step for generating synchronization data synchronized to a predetermined frequency;
A channel corresponding to the RLL recording code from the synchronization data generated by the phase synchronization means according to a third algorithm corresponding to the first algorithm or a fourth algorithm corresponding to the second algorithm A data detection step for detecting a bit string;
A decoding step of decoding the channel bit string detected by the processing of the data detection step;
Based on the data sequence that is generated, detected, or used by at least one of the phase synchronization step, the data detection step, and the decoding step and does not have identification information individually, And a switching determination step for determining a first switching between the first algorithm and the second algorithm and a second switching between the third algorithm and the fourth algorithm. Program to do.

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