JP2004118924A - Information recording/reproducing device and information reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an information recording/reproducing device and an information reproducing method, by which data are reproducible comparatively highly precisely even though the intersymbol interference is furthermore developed. <P>SOLUTION: Test data are recorded at the top position of a recording unit. At the reproduction, the impulse response h(t) of the recording/reproducing system (including disk) is derived by reproducing the test data at first. A reproduction RF signal of each of sample data in a sample data memory 17 is presumed on the basis of this impulse response h(t), and data of sample value which the reproduction RF signal is subjected to A/D conversion, are transmitted to a comparison circuit 14 from a presumed pattern producing circuit 16. By the comparison circuit 14, the difference between these sample value data and sample value data of the reproduction RF signal actually reproduced from the disk is calculated to specify such sample data that this difference becomes minimum. The specified sample data are outputted as the reproduced data by a reproduction data selecting circuit 18. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an information recording / reproducing device and an information reproducing method, and is particularly suitable for use in a sample servo type optical disk recording / reproducing device.
[0002]
[Prior art]
With the development and progress of IT infrastructure, there is a demand for further increase in the capacity of optical discs. In order to meet such demands, it is necessary to further reduce the pit length and the pit interval in order to increase the recording density of the optical disk. However, in such a case, a new problem such as deterioration of reproduction characteristics due to intersymbol interference occurs.
[0003]
Such a problem of intersymbol interference can be suppressed by performing a waveform equalization process using an equalizer filter or the like on the reproduced signal. However, if the pit length and the pit interval are further shortened to improve the recording density, an equalization error occurs, affecting adjacent waveforms or emphasizing noise, so that sufficient reproduction characteristics cannot be obtained. .
[0004]
Therefore, for high-density recording in which the influence of intersymbol interference cannot be removed even by waveform equalization processing, a data reproduction method to which Viterbi decoding processing is applied is adopted. In the Viterbi decoding process, the inter-symbol interference is positively used in reverse, and the signal path is detected by selecting the decoding path having the highest likelihood. Note that high-density recording using Viterbi decoding processing is described in, for example, “High-density recording by Viterbi decoding”, Technical Report of the Institute of Television Engineers of Japan, Vol. 14, No. 64, pp13-17, Vir'90-63, (Sep. 1990).
[0005]
However, even when such Viterbi decoding processing is employed, the threshold value set for the above-mentioned likelihood comparison remains unchanged if the conditions / environments during recording / reproduction such as fluctuations in the disk-side characteristics and recording laser power change. In this case, the data does not match the conditions and environment. Therefore, if the Viterbi decoding process is executed with the set threshold value, an error in data reproduction is increased.
[0006]
In view of the above, there has been proposed a method in which conditions and environments at the time of recording and reproduction are detected in advance, and a threshold for likelihood comparison is appropriately adjusted according to the detection result (for example, see Patent Document 1).
[0007]
[Patent Document 1]
JP-A-6-37650
[0008]
[Problems to be solved by the invention]
However, if the density of the recording medium is further increased and the S / N of the reproduced waveform is significantly deteriorated due to intersymbol interference, it becomes difficult to appropriately select a decoding path in the Viterbi decoding process. Therefore, even if the threshold value is adjusted as described above, errors in selecting a decoding path due to S / N deterioration of a reproduced waveform increase, which causes a problem that proper data cannot be reproduced. .
[0009]
Thus, the present invention provides an information recording / reproducing apparatus and an information reproducing method capable of avoiding such a problem in the Viterbi decoding process and reproducing data with relatively high accuracy even if intersymbol interference further advances.
[0010]
[Means for Solving the Problems]
In view of the above problems, the present invention has the following features.
[0011]
The invention according to claim 1 relates to an information recording / reproducing apparatus, wherein test data recording means for recording test data in a predetermined area on a recording medium, and reproducing the test data and recording the data on the recording medium. Recording and reproduction characteristic deriving means for deriving recording and reproduction characteristics at the time of reproduction; sample data storage means for storing sample data according to a modulation method; and a sample for generating a reproduction signal from the sample data based on the recording and reproduction characteristics. Reproduction signal generation means for comparing the generated sample reproduction signal with the reproduction signal reproduced from the recording medium, and using the sample data corresponding to the sample reproduction signal closest to the reproduced reproduction signal as reproduction data Reproduction data output means for outputting.
[0012]
The invention according to claim 2 is the information recording / reproducing apparatus according to claim 1, further comprising sampling means for sampling a reproduction signal reproduced from the recording medium at a predetermined cycle to derive a sample value, and The means generates a sample value according to the sampling cycle from the sample data based on the recording / reproducing characteristics, and the reproduced data output means outputs the sample value derived by the sampling means and the sample reproduced signal generating means. The reproduction data is output by comparing the generated sample value.
[0013]
According to a third aspect of the present invention, in the information recording / reproducing apparatus according to the second aspect, the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string. The reproduction data output means outputs a sample reproduction signal of sample data in which the bit positions from the largest one to the J-th (J> K) among the sample values at each bit position become 1, and the reproduction signal reproduced from the recording medium. And outputting the reproduction data.
[0014]
According to a fourth aspect of the present invention, in the information recording / reproducing apparatus according to the second aspect, the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string. The reproduction data output means outputs a sample reproduction signal of sample data in which the bit position from the largest sample value at each bit position to the J-th (J> K) and the adjacent bit position become 1; And reproducing the reproduced data by comparing the reproduced data with a reproduced signal reproduced from the.
[0015]
According to a fifth aspect of the present invention, in the information recording / reproducing apparatus according to any one of the second to fourth aspects, the reproduced data output unit generates the sample value derived by the sampling unit and the sample reproduction signal generation unit. The method is characterized in that a sum of square errors of sample values is calculated, and sample data corresponding to a sample reproduction signal having the smallest sum of the square errors is output as reproduction data.
[0016]
According to a sixth aspect of the present invention, in the information recording / reproducing apparatus according to any one of the first to fifth aspects, the test data recording unit is configured such that a recording area of the recording medium is physically or logically divided into a plurality of areas. The test data is recorded at a position prior to data recording of each section, and the recording / reproducing characteristic deriving means derives the recording / reproducing characteristic of the section by reproducing the test data, The sample reproduction signal generation means generates a sample reproduction signal of the section from the sample data based on the recording / reproduction characteristics of each section, and the reproduction data output means outputs the sample reproduction signal generated for each section and the recording medium. And reproducing the reproduced data by comparing the reproduced signal with the reproduced signal.
[0017]
The invention of claim 7 relates to an information reproducing method, in which test data recorded in a predetermined area on a recording medium is reproduced to derive recording / reproducing characteristics when recording and reproducing data on the recording medium. A recording / reproducing characteristic deriving step; a sample reproducing signal generating step of sequentially reading out the sample data stored in the storage means and generating a reproducing signal from the sample data based on the recording / reproducing characteristics; And a reproduction data reproduced from the recording medium, and a reproduction data output step of outputting sample data corresponding to a sample reproduction signal closest to the reproduced reproduction signal as reproduction data. I do.
[0018]
The invention according to claim 8 is the information reproducing method according to claim 7, further comprising a sampling step of sampling a reproduction signal reproduced from the recording medium at a predetermined cycle to derive a sample value, wherein the sample reproduction signal generation step Generating a sample value corresponding to the sampling period from the sample data based on the recording / reproducing characteristics, and the reproducing data output step includes generating the sample value derived by the sampling step and the sample reproduction signal generating step. And outputting the reproduced data by comparing the sampled data with the sampled data.
[0019]
According to a ninth aspect of the present invention, in the information reproducing method according to the eighth aspect, when the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string, The reproducing data output step includes the steps of: reproducing a sample reproduction signal of sample data in which the bit positions from the largest sample value at each bit position to the J-th (J> K) bit position become 1, a reproduction signal reproduced from the recording medium; And outputting the reproduction data.
[0020]
According to a tenth aspect of the present invention, in the information reproducing method according to the eighth aspect, when the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string, The reproducing data output step includes the steps of: reproducing a sample reproduction signal of sample data in which the bit positions from the largest to the J-th (J> K) among the sample values at each bit position and the adjacent bit position become 1; The reproduced data is output by comparing the reproduced data with a reproduced signal.
[0021]
According to an eleventh aspect of the present invention, in the information reproducing method according to any one of the eighth to tenth aspects, the reproduced data output step includes the step of generating the sample value derived by the sampling step and the sample generated by the sample reproduced signal generating step. The sum of the square errors of the values is calculated, and the sample data corresponding to the sample playback signal having the smallest sum of the square errors is output as the playback data.
[0022]
According to a twelfth aspect of the present invention, in the information reproducing method according to any one of the seventh to eleventh aspects, the recording area of the recording medium is physically or logically divided into a plurality of areas. When the test data is recorded at a position prior to data recording, the recording / reproduction characteristic deriving step derives the recording / reproduction characteristic of the section by reproducing the test data, and the sample reproduction signal generation step Generating a sample reproduction signal of the section from the sample data based on the recording / reproducing characteristics of each section, and outputting the reproduced data in the step of reproducing the sample reproduction signal generated for each section and the reproduction reproduced from the recording medium. The reproduction data is output by comparing with a signal.
[0023]
According to the present invention, it is possible to derive the recording / reproducing characteristics under the current environment and conditions from the reproduction result of the test data. Such recording / reproducing characteristics can be expressed, for example, as an impulse response when a recording / reproducing system and a recording medium interposed therebetween are regarded as a transmission path. If a reproduced waveform is calculated from sample data using such an impulse response as a transfer function, the reproduced waveform of any sample data should be the expected value of the reproduced waveform of the reproduced signal actually reproduced from the recording medium. Therefore, in the present invention, among the reproduction waveforms calculated from the sample data, the one that most closely matches the reproduction waveform actually reproduced from the recording medium is set as the expected value of the reproduced reproduction waveform, and the reproduction waveform set as the expected value is used. The sample data from which is calculated is assumed to be reproduction data from the recording medium.
[0024]
Here, the reproduced waveform calculated from the sample data includes the impulse response (transfer function) itself including the deterioration of the S / N due to the intersymbol interference. Even if the S / N is deteriorated due to the interference, the reproduced waveform of the sample data to be set as the expected value and the reproduced waveform of the reproduced signal actually reproduced from the recording medium are relatively accurately matched.
[0025]
Therefore, according to the present invention, reproduced data can be generated from a high-density recording medium with relatively high accuracy in accordance with the environment and conditions at that time.
[0026]
In the inventions described in the above claims, the recording medium broadly includes a rewritable optical disk, a write-once optical disk, a magneto-optical disk, and the like. In addition to the method of recording the test data only once in a predetermined area, the test data may be repeatedly recorded in the area. Alternatively, several types of test data may be recorded, and the recording / reproducing characteristics may be derived according to the reproduction result of each test data. Further, the test data may be recorded a plurality of times by switching the recording power, and the recording / reproducing characteristics may be derived according to the reproduction result.
[0027]
The features of the present invention will become more apparent from the following description of embodiments.
[0028]
However, the following embodiments are merely one embodiment of the present invention, and the meanings of the terms of the present invention and each component are not limited to those described in the following embodiments. Absent.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0030]
First, FIG. 1 shows a track / sector format of a sample servo optical disk (hereinafter, referred to as a “disk”) according to an embodiment.
[0031]
As shown in the figure, one track (for one round of the disk) is composed of 32 sectors (sector 0 to sector 31). One sector is composed of one sector header and 43 blocks (block 1 to block 43). Further, one block is composed of a 2-byte servo field and a 16-byte data field.
[0032]
In the area corresponding to the sector header on the disk, header information is recorded in advance as pits. Further, in a region corresponding to the servo field, pits for tracking servo and pits for clock generation are recorded in advance.
[0033]
FIG. 2 shows a pit pattern of the servo field. As shown in the figure, the pit pattern of the servo field is either the A pattern or the B pattern. That is, pits are formed on the disk such that the A pattern and the B pattern are alternately arranged every 16 tracks. In the figure, P11 and P12 and P21 and P22 are pits for tracking servo, and P13 and P23 are pits for clock reproduction.
[0034]
Here, P11 and P21 are slightly displaced in the disk radial direction with respect to the track center axis. Further, P12 and P22 are slightly displaced in the direction opposite to the displacement direction of P11 and P21. Therefore, a tracking error signal can be obtained from a detection signal when scanning the pair of P11 and P12 and the pair of P21 and P22. As described above, in the disk, a tracking error signal can be obtained by a set of pits formed in the sample servo field, so that a guide groove for tracking control becomes unnecessary.
[0035]
The clock pits P13 and P23 are formed at fixed positions in the servo field. Therefore, a detection signal when scanning such a clock pit is generated at a constant period. By applying a PLL (Phase-Locked-Loop) using such a detection signal as a comparison signal, a reproduction clock synchronized with each bit of the data field and a sampling clock (for generating sample value data) described later can be generated.
[0036]
The details of the sample servo type optical disk are described in, for example, SPIE, Vol. 695, Optical Mass Data Storage 2 (1986). For details of tracking servo (sample servo) using prepits formed in a servo field, see, for example, SPIE, Vol. 529, Third International Conference on Optical Mass Data Storage (1985).
[0037]
FIG. 3 shows a recording / reproducing apparatus for recording / reproducing information on / from a disc.
[0038]
In the figure, 1 is a control circuit for controlling each part, 2 is an ECC encoder that adds an error correction code to recording data, and 3 is a code modulation such as a 4/11 code on the error-corrected recording data. Is applied to the modulation circuit.
[0039]
Here, the 4/11 code is a coding method in which 8 bits are converted into 11 bits, and 4 1's exist in 11 bits after coding, and the number of consecutive 1's is 3 or less. It is a method. The details of the 4/11 code are described in, for example, Japanese Patent No. 2606265.
[0040]
Reference numeral 4 denotes a test pattern generation circuit that repeatedly outputs 11-bit test data a predetermined number of times, 5 denotes a drive signal generation circuit that converts data from the modulation circuit 3 or the test pattern generation circuit 4 into a recording waveform signal, and 6 denotes a drive signal. A laser drive circuit for driving a semiconductor laser in accordance with a drive signal (recording waveform signal) from a generation circuit 5 or a command from the control circuit 1; a semiconductor laser 7a for emitting laser light for recording / reproduction and reflection from a disk This is an optical pickup having a photodetector 7b that receives light.
[0041]
Reference numeral 8 denotes a reproduction signal amplifier circuit for amplifying a detection signal from the photodetector 7b, and reference numeral 9 denotes a servo signal based on a focus error signal, a tracking error signal, and a clock pit detection signal among the detection signals from the photodetector 7b. A servo circuit 10 controls a convergence position of a laser beam emitted from the optical pickup 7 according to a focus servo signal and a tracking servo signal from the servo circuit 9, and 11 corresponds to a rotation servo signal from the servo circuit 9. The spindle motor drives the disk at a predetermined rotation speed.
[0042]
Reference numeral 12 denotes an A / D converter which samples the reproduction RF signal from the reproduction signal amplifier circuit 8 at a predetermined period and converts the sample value at each sampling timing into digital data. Reference numeral 13 denotes the sample value data from the A / D converter 12 sequentially. A memory 14 for storing is a comparison circuit for calculating a sum Ve of square errors between sample sample value data from an assumed pattern generation circuit 16 (described later) and sample value data stored in the memory 13.
[0043]
Reference numeral 15 denotes a test pattern extraction circuit for extracting a test data section from the reproduction RF signal from the reproduction signal amplification circuit 8, and reference numeral 16 denotes a reproduction RF signal assuming that the sampling data is recorded on the disk and reproduced. The assumed pattern generation circuit 17 generates sample value data (sample sample value data) sampled at the same sampling cycle as that of the / D converter 12, and the test data 17 and all data patterns of the 4/11 code are used as sample data. A sample data memory for storing, 18 is a reproduction data selection circuit for reading out from the sample data memory 17 sample data having the smallest Ve calculated by the comparison circuit 14 and sequentially outputting the same as reproduction data, and 19 has a built-in PLL. Compare the clock pit detection signal from the reproduction signal amplification circuit 8 with the comparison signal. A clock generation circuit for generating a reproduction clock and a sampling clock as.
[0044]
Note that the assumed pattern generation circuit 16 generates sample sample value data from sample data as follows.
[0045]
First, based on the reproduced waveform signal from the test pattern extraction circuit 15 and the test data stored in the sample data memory 17, the impulse response h (t) (transfer function) of the recording / reproducing system (transmission path) at the time of the reproducing is performed. ) Is calculated. Next, based on the impulse response h (t), an expected value g (t) of the reproduced RF signal of the sample data is obtained.
[0046]
Here, when the recording waveform signal of the sample data is s (t), the expected value g (t) is given by a convolution value of the recording waveform signal s (t) and the impulse response h (t). That is, the expected value g (t) of the reproduced RF signal is
g (t) = s (t) ^* h (t) (1)
Can be calculated by
[0047]
The sample sample value data is given by the peak value at the sampling timing of the reproduced RF signal represented by the expected value g (t). That is, assuming that the sampling timings are t1, t2,..., Tn, the sample sample value data is given by g (t1), g (t2),.
[0048]
The assumed pattern generation circuit 16 calculates g (t1), g (t2),..., G (tn) for the sampled data read from the sample data memory 17 based on the expression (1), thereby obtaining the sampled data. Calculate sample sample value data of the data.
[0049]
Next, an operation at the time of recording in the recording / reproducing apparatus will be described.
[0050]
When the optical pickup 7 is accessed according to the recording instruction and the sector header of the recording start sector is detected, the test data from the test pattern generation circuit 4 is repeatedly supplied to the drive signal generation circuit 5 a predetermined number of times. The test data is written at the start position of the data field of the first block (block 1) of the sector. As a result, a pit corresponding to the test data is formed at the start position of the data field.
[0051]
When the writing of the test data is completed, the recording data from the modulation circuit 3 is sequentially supplied to the drive signal generation circuit 5. Such recording data is sequentially written in the data field of block 1 following the recording end position of the test data. Thus, pits corresponding to the recording data are formed following the test data pits.
[0052]
The writing of the recording data is continued until the end position of the sector, that is, the end position of the data field of the block 43. When the scanning position of the laser beam shifts to the next sector and the sector header of the sector is detected, the test data from the test pattern generation circuit 4 is repeatedly supplied to the drive signal generation circuit 5 a predetermined number of times. You. Thus, the test data is written at the start position of the data field of block 1 of the sector. Thereafter, the recording data from the recording data modulation circuit 3 is supplied to the drive signal generation circuit 5, and the recording data is written in the same manner as described above.
[0053]
Similarly, every time a sector shift occurs, test data is written at the start position of the data field of the head block of each sector. The recording data is sequentially written to the remaining area of the data field of each sector excluding the recording area of the test data.
[0054]
Next, the operation at the time of reproduction in the recording / reproducing apparatus will be described.
[0055]
First, the processing operation in the circuit system of the A / D converter 12 to the reproduction data selection circuit 18 will be described with reference to the timing chart of FIG.
[0056]
When a laser beam scans a recording pit as shown in FIG. 7A, a reproduced RF signal as shown in FIGS. FIGS. 6B to 6D show reproduced RF signals when the recording densities are different from each other, and FIG. 7C shows the reproduced RF signals when the recording density is higher than FIG. FIG. 3D shows a reproduced RF signal when the recording density is higher than that in FIG.
[0057]
For example, if the reproduction RF signal shown in FIG. 3C is output from the reproduction signal amplification circuit 8 during the reproduction, the A / D converter 12 receives the reproduction RF signal and converts the reproduction RF signal into the same signal. The sample value data sampled by the sampling clock shown in FIG.
[0058]
The comparison circuit 14 refers to the sample value data stored in the memory 13 and among the bit positions in the reproduced RF signal, the bit positions (from the largest sample value data to the Jth (for example, J = 5)). (Arrow position in FIG. 3C). Then, of the sample data in the sample data memory 17, sample sample value data is generated in the assumed pattern generation circuit 16 only for sample data in which all four 1s included therein correspond to any of the bit positions. Let me know.
[0059]
The comparison circuit 14 calculates the sum Ve of the square errors between the sampled sample data and the sampled data stored in the memory 13 for each of the sample data to be compared.
[0060]
Now, the sample value data of the reproduced RF signal for 11 bits stored in the memory 13 is Vs1 (i) (i = 1 to n), and the sample value data of the sample data output from the assumed pattern generation circuit 16 is Vs2. (I) If (i = 1 to n), the above Ve is
Ve = Σ (Vs1 (i) −Vs2 (i)) ² ... (2)
Given by
[0061]
The comparison circuit 14 calculates Ve for each sample data based on the equation (2), and compares the calculated Ve. Then, the reproduction data selection circuit 18 is notified of the sample data having the smallest Ve. In response to this, the reproduction data selection circuit 18 reads the sample data from the sample data memory 17 and outputs this as reproduction data.
[0062]
In the above description, the number J of bit positions to be set to 1 (significant) may be set to a number larger than the number K when the number of 1s included in the coding unit is predetermined. . This makes it possible to efficiently narrow down the sample data that is a comparison candidate, and reduce the number of calculation processes while suppressing the selection error of the reproduction data.
[0063]
Next, an operation at the time of reproduction will be described with reference to FIG.
[0064]
When the optical pickup 7 accesses the reproduction start sector according to the recording instruction, first, the test pattern extraction circuit 15 extracts the reproduction RF signal of the test data written in the data field start position of the head block of the sector (S101). ), Which is sent to the assumed pattern generation circuit 16. The assumed pattern generation circuit 16 calculates an impulse response h (t) of the recording / reproducing system at the time of the reproduction based on the RF signal (S102).
[0065]
Thereafter, when reading of the recording data written following the test data is started, the reproduced RF signal is A / D converted by the A / D converter 12, and the sample value data is sequentially stored in the memory. . The comparison circuit 14 refers to the sample value data of the first 11-bit equivalent section among the sample value data stored in the memory 13 (S103), and of the bit positions of the 11-bit equivalent section, The bit positions from the largest to the J-th (for example, J = 5) are determined (S104). Then, out of the sample data in the sample data memory 17, only the sample data in which all four 1s correspond to any of the bit positions are generated, and the assumed pattern generation circuit 16 generates the sample sample value data ( S105).
[0066]
When the sample sample value data is generated, the comparison circuit 14 next calculates the sum Ve of the square errors between the sample sample value data and the sample value data in the memory 13 (S106). Then, the calculated Ve is compared in magnitude, and the sample data with the smallest Ve is specified. In response to the specification, the reproduction data selection circuit 18 reads the specified sample data from the sample data memory 17. Then, the read sample data is output to the subsequent circuit as reproduction data (S107).
[0067]
When the reproduction data is output for the first 11-bit equivalent section, the process returns to S103, and the sample value data of the next 11-bit equivalent section is referred to from the memory 13. Then, in the same manner as described above, the sample data corresponding to the section corresponding to the 11 bits is specified by the comparison circuit 14, and the sample data is output to the subsequent circuit as reproduction data (S104 to S107).
[0068]
The output of such reproduction data is repeated until the scanning position shifts to the next sector. When the transition to the next sector is detected (S108), the process returns to S101, where the reproduction RF signal of the test data written in the data field start position of the start block of the sector is output by the test pattern extraction circuit 15. It is extracted and sent to the assumed pattern generation circuit 16. Then, the impulse response h (t) applied to the sector is calculated by the assumed pattern generation circuit 16 (S102), and based on this, sample sample value data is generated. Then, as described above, Ve is calculated between the sample sample value data and the sample value data in the memory 13, and the sample data with the smallest Ve is output as reproduction data (S103 to S108).
[0069]
The output of such reproduction data is repeated until the scanning position shifts to the next sector. Then, when the transition to the next sector is detected (S108), the impulse response h (t) is reset (S101, S102) in the same manner as described above, and based on this, the reproduction data is output. (S103 to S108).
[0070]
According to the above-described embodiment, the impulse response h (t) of the recording / reproducing system (including the disc) is detected from the reproduced RF signal of the test data each time, and the sample data is detected based on the impulse response h (t). The sampled data is generated, and the sampled data is compared with the sampled data of an actually reproduced RF signal to selectively output sample data. Therefore, the recording density of the disk is further improved. Even if intersymbol interference further advances as shown in FIG. 4 (d), reproduced data can be generated and output with high accuracy according to changes in the environment and conditions of the recording / reproducing system.
[0071]
The embodiments according to the present invention have been described above, but it goes without saying that the present invention is not limited to these embodiments.
[0072]
For example, in the above embodiment, only the sample data in which the bit position from the largest sample value data to the J-th bit is 1 (significant) is to be compared. However, as shown in FIG. The sample data in which the bit position up to the first bit and the bit position adjacent thereto are 1 (significant) may be set as a comparison target (see S110 in FIG. 6). In such a case, the number of sample data to be compared increases as compared with the case of the above embodiment, but the probability of specifying erroneous sample data as reproduction data decreases. Therefore, the amount of arithmetic processing for outputting reproduced data is increased as compared with the above embodiment, but the error rate of reproduced data can be reduced.
[0073]
In the above embodiment, the test data is written for each sector, and the impulse response h (t) used for reproduction is switched for each sector. However, the test data is written for several or tens of sectors. The impulse response h (t) may be switched for each sector.
[0074]
Further, the test data may be repeatedly recorded at the data field start position of the start block (block 1), or may be recorded only once at that position. Several types of test data are recorded in the area, and The impulse response h (t) may be calculated according to the result of reproducing the test data. Further, test data may be recorded a plurality of times by switching the laser power, and h (t) may be calculated according to the reproduction result.
[0075]
Further, in the above embodiment, the sample data most matching the reproduction RF signal is selected by calculating the sum Ve of the square errors of the sample value data. The data may be determined, and the sample data may be selectively output in accordance with the determination.
[0076]
In the above embodiment, the sampling clock is generated by the PLL (clock generation circuit 19) using the clock pit detection signal as the comparison signal. However, the sampling clock is generated using an oscillator that transmits a fixed clock such as a crystal clock. You may do so.
[0077]
Further, in the above-described embodiment, the 4/11 encoding method is adopted as the encoding method of the modulation circuit 3, but other encoding methods can be adopted.
[0078]
In addition, the types of the recording / reproducing system and the optical disk are not limited to those of the above-described embodiment, but may be other rewritable optical disks, write-once optical disks, magneto-optical disks, and the like.
[0079]
Various modifications can be made to the embodiments according to the present invention within the scope of the technical idea of the present invention.
[0080]
【The invention's effect】
According to the present invention, characteristics of a recording / reproducing system (including a recording medium) are detected from a reproduced signal at each time, a reproduced signal is generated from sample data based on the characteristics, and the reproduced signal is actually reproduced from the sample reproduced signal. Since the sample data of the sample reproduction signal that most closely matches the reproduced signal thus output is output as reproduction data, even if the recording density of the recording medium is further improved and intersymbol interference is further advanced, the recording / reproduction may be performed at each time. Even if the environment and conditions of the system change, it is possible to generate and output reproduced data relatively accurately.
[Brief description of the drawings]
FIG. 1 is a diagram showing a sector format of an optical disc according to an embodiment;
FIG. 2 is a diagram showing a pit pattern of a servo field of the optical disc.
FIG. 3 is a diagram showing a configuration of a recording / reproducing apparatus according to an embodiment.
FIG. 4 is a timing chart for explaining a reproduction data generation method;
FIG. 5 is a flowchart showing a reproducing operation of the recording / reproducing apparatus.
FIG. 6 is a flowchart showing another reproduction operation.
[Explanation of symbols]
1 control circuit
4 Test pattern generation circuit
12 A / D converter
13 memory
14 Comparison circuit
15 Test pattern extraction circuit
16 Assumed pattern generation circuit
17 Sample data memory
18 Reproduction data selection circuit
19 Clock generation circuit

Claims (12)

Test data recording means for recording test data in a predetermined area on a recording medium,
A recording / reproducing characteristic deriving means for deriving recording / reproducing characteristics when reproducing the test data and recording / reproducing data on the recording medium,
Sample data storage means for storing sample data according to the modulation method,
Sample reproduction signal generation means for generating a reproduction signal from the sample data based on the recording and reproduction characteristics,
Reproduction data output means for comparing the generated sample reproduction signal with a reproduction signal reproduced from the recording medium and outputting sample data corresponding to the sample reproduction signal closest to the reproduced reproduction signal as reproduction data; When,
An information recording / reproducing apparatus comprising: In claim 1,
Sampling means for sampling a reproduction signal reproduced from the recording medium at a predetermined cycle to derive a sample value,
The sample reproduction signal generation unit generates a sample value according to the sampling period from the sample data based on the recording and reproduction characteristics,
The reproduction data output unit compares the sample value derived by the sampling unit with the sample value generated by the sample reproduction signal generation unit, and outputs the reproduction data.
An information recording / reproducing apparatus characterized by the above-mentioned. In claim 2,
When the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string,
The reproduction data output means outputs a sample reproduction signal of sample data in which the bit positions from the largest one to the J-th (J> K) among the sample values at each bit position become 1, and a reproduction signal reproduced from the recording medium. An information recording / reproducing apparatus characterized in that the reproduced data is output by comparing the information. In claim 2,
When the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string,
The reproduction data output means outputs a sample reproduction signal of the sample data in which the bit position from the largest one to the J-th (J> K) among the sample values at each bit position and the bit position adjacent thereto are 1 and the recording medium. Outputting the reproduced data by comparing the reproduced signal with a reproduced signal;
An information recording / reproducing apparatus characterized by the above-mentioned. In any one of claims 2 to 4,
The reproduction data output means calculates the sum of square errors of the sample values derived by the sampling means and the sample values generated by the sample reproduction signal generation means, and corresponds to the sample reproduction signal having the smallest sum of the square errors. Output sample data as playback data,
An information recording / reproducing apparatus characterized by the above-mentioned. In any one of claims 1 to 5,
When the recording area of the recording medium is physically or logically divided into a plurality of areas, the test data recording unit records the test data at a position prior to data recording of each section,
The recording / reproducing characteristics deriving unit derives the recording / reproducing characteristics of the section by reproducing the test data,
The sample reproduction signal generation means generates a sample reproduction signal of the section from the sample data based on the recording and reproduction characteristics of each section,
Reproduction data output means for comparing the sample reproduction signal generated for each section with a reproduction signal reproduced from the recording medium and outputting the result as reproduction data;
An information recording / reproducing apparatus characterized by the above-mentioned. A recording / reproduction characteristic deriving step of deriving recording / reproduction characteristics when reproducing test data recorded in a predetermined area on a recording medium and recording / reproducing data on the recording medium,
A sample reproduction signal generating step of sequentially reading the sample data stored in the storage means and generating a reproduction signal from the sample data based on the recording and reproduction characteristics;
A reproduction data output step of comparing the generated sample reproduction signal with a reproduction signal reproduced from the recording medium and outputting sample data corresponding to the sample reproduction signal closest to the reproduced reproduction signal as reproduction data; When,
An information reproducing method comprising: In claim 7,
The apparatus further includes a sampling step of deriving a sample value by sampling a reproduction signal reproduced from the recording medium at a predetermined cycle,
The sample reproduction signal generation step generates a sample value according to the sampling period from the sample data based on the recording and reproduction characteristics,
The reproduction data output step compares the sample value derived by the sampling step with the sample value generated by the sample reproduction signal generation step, and outputs the reproduction data.
An information reproducing method, characterized in that: In claim 8,
When the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string,
The reproducing data output step includes the steps of: reproducing a sample reproduction signal of sample data in which the bit positions from the largest sample value at each bit position to the J-th (J> K) bit position become 1, a reproduction signal reproduced from the recording medium; And outputting the reproduced data by comparing
An information reproducing method, characterized in that: In claim 8,
When the recording data is encoded by an encoding process in which K 1s exist in the encoded N-bit code string,
The reproducing data output step includes the steps of: reproducing a sample reproduction signal of sample data in which the bit positions from the largest to the J-th (J> K) among the sample values at each bit position and the adjacent bit position become 1; Outputting the reproduced data by comparing the reproduced signal with a reproduced signal;
An information reproducing method, characterized in that: In any one of claims 8 to 10,
The reproduction data output step calculates the sum of square errors of the sample values derived in the sampling step and the sample values generated in the sample reproduction signal generation step, and corresponds to the sample reproduction signal having the smallest sum of the square errors. Output sample data as playback data,
An information reproducing method, characterized in that: In any one of claims 7 to 11,
When the recording area of the recording medium is physically or logically divided into a plurality of areas, and the test data is recorded at a position prior to data recording of each section,
The recording / reproducing characteristics deriving step derives the recording / reproducing characteristics of the section by reproducing the test data,
The sample reproduction signal generation step generates a sample reproduction signal of the section from the sample data based on the recording and reproduction characteristics of each section,
The reproduction data output step compares the sample reproduction signal generated for each section with a reproduction signal reproduced from the recording medium, and outputs reproduction data.
An information reproducing method, characterized in that:

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