JP2016004598A - Optical information recording medium, recording method, and method for evaluating medium quality - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the number of recording pulse waveform correction parameters that constitute an adaptive recording compensation table.SOLUTION: Among the correction parameters that constitute an adaptive recording compensation table, only some correction parameters (default parameters) are previously assigned, and the remaining correction parameters (undetermined parameters) are calculated by interpolation using the default parameters. Information is recorded by a recording waveform generated using the calculated correction parameters.

Description

  The present invention relates to an optical information recording medium technique, a recording technique, and a medium quality evaluation technique for recording information on an optical disc with high density.

<RLL code>
In an optical disk that is currently in widespread use, mark edge recording is performed in which information is recorded by irradiating a recording medium with laser light to form a plurality of marks and spaces between marks. User data is modulated using an RLL (run length limited) code that limits the number of consecutive “0” s, then converted to NRZI (non return to zero inverted), and marked with “1” and “0”. It is recorded on the medium allocated to space. The RLL code is generally expressed as RLL (d, k), where d and k are the minimum value (shortest run length) and maximum value (the shortest run length) of 0 appearing between 1 and 1 of the encoded data, respectively. Longest run length). For example, an optical disc system that uses a blue laser light source having a wavelength of 405 nm and an objective lens having a numerical aperture (NA) of 0.85 and records information using RLL (1, 7) as an RLL code has been put into practical use. When RLL (1, 7) is used, the types of lengths of marks and spaces formed on the medium are 2T, 3T, 4T, 5T, 6T, 7T, and 8T, where T is the channel bit length. .

<Recording strategy>
When recording information on an optical disc, it is generally performed to irradiate a medium while changing light of a plurality of power levels at an appropriate timing. This method of changing the power level is called a recording strategy. FIG. 1 is a diagram showing an example of a recording strategy when RLL (1, 7) is used. Here, a recording pulse waveform for representatively forming 2T, 3T, 4T, and 5T marks among 2T to 8T length marks constituting RLL (1, 7) is shown. Pw, Ps, and Pc are irradiation light power levels. Pw (peak power) is used to form a mark by heating the recording film material to a reaction temperature or higher. Ps (space power) is used to irradiate the space forming region and perform preheating. Pc (cooling power) is set to a level lower than Pw and Ps, and is used to reduce thermal interference between marks. DTtop, dTc, and dTs are recording pulse waveform timing correction parameters. dTtop is a correction parameter for the start edge of the recording pulse and is involved in determining the position of the front edge of the mark. dTc is a correction parameter at the end of the recording pulse and is involved in determining the position of the trailing edge of the mark. dTs is a correction parameter for the cooling pulse width and is involved in the control of thermal interference between marks.

<Adaptive record compensation>
When recording information on an optical disc at high density, the edge position of the mark formed according to the length of the mark to be recorded and the length of the adjacent space (mark interval) due to the effects of heat accumulation and thermal interference in the recording film Is a problem. To compensate for this, the above-mentioned recording pulse waveform correction parameters (dTtop, dTc, and dTs) are individually set for each combination of mark length and space length, and the mark edge position is corrected. A method called recording compensation is generally used. FIG. 2 shows an example of a table in which the values of the correction parameters of the recording pulse waveform are classified and described according to combinations of mark length and space length. Such a table is referred to as an adaptive recording compensation table in this specification. In the adaptive recording compensation table of FIG. 2, the horizontal direction is classified by the mark length, and the vertical direction is classified by the space length. In this example, the value of dTtop is set individually for each combination of the recording mark and the space length preceding it into four types of 2T, 3T, 4T, and 5T or more. The values of dTc and dTs are set individually for each combination of the recording mark and the space length following it, classified into four types of 2T, 3T, 4T, and 5T or more. Here, the necessary and sufficient size of the adaptive recording compensation table (number of mark lengths and space lengths) is determined based on the range affected by thermal interference.

<Media control information (DI)>
Patent Document 1 discloses an optical disc medium in which correction parameters in the above-described adaptive recording compensation table are recorded in a prerecorded area or an embossed area as part of various information (medium control information) for recording / reproducing of the disk. Have been described.

<Edge shift detection method>
In order to optimize and adjust the recording pulse waveform, an edge shift (shift from the ideal position of the mark edge) is detected from the reproduction signal, and the correction parameter of the recording pulse waveform is adjusted so as to minimize this. Generally done. As a method for detecting the edge shift, a method based on the edge error of the reproduction signal and the phase error of the reproduction clock, or a method based on the Euclidean distance between the reproduction signal and the target signal is generally used.

US2006 / 0215512

<When the shortest run length d is increased, the size of the adaptive recording compensation table is enlarged>
In order to increase the recording capacity per recording layer in response to the demand for an increase in the capacity of optical discs, development of techniques for improving the linear recording density (the amount of information per length in the track direction) has been underway. Up to now, the improvement in linear recording density in optical discs has been made mainly by miniaturizing the light spot by shortening the wavelength of the laser light source and increasing the NA of the objective lens, but this method has almost reached its limit. On the other hand, the room for improving the linear recording density by reducing the detection window width Tw is expanding due to the recent improvement in the quality of recording media and the reduction in noise of the photodetector amplifier. Therefore, there is an attempt to improve the linear recording density by increasing the shortest run length d in the RLL (d, k) code while maintaining the physical length of the shortest mark. FIG. 3 is a diagram comparing the lengths of the marks in each case of the shortest run lengths d = 1 and d = 3 under the condition that the physical lengths of the shortest marks are the same. The shortest mark lengths for d = 1 and d = 3 are 2T and 4T, respectively. As shown in this figure, since the length of the 2T mark when d = 1 is equal to the length of the 4T mark when d = 3, by increasing the shortest run length d from 1 to 3, channel bits are increased. The length T is reduced to ½, and the linear recording density is increased.

However, there is a problem that the size of the adaptive recording compensation table is enlarged by increasing the shortest run length d. FIG. 4A shows an example of an adaptive recording compensation table of the correction parameter dTtop of the recording pulse waveform when d = 1. The value of dTtop is classified into four types in which the recording mark length and the space length preceding the recording mark length are 2T, 3T, 4T, and 5T or more, respectively, and are given for each combination pattern. Here, regarding the way of notation of the parameter name, for example, dTtop for a pattern having a preceding space length of 3T and a recording mark length of 4T is represented as dTtop ₃₄ .

  Next, consider increasing the shortest run length d from 1 to 3 while maintaining the physical length of the shortest mark. In the case of d = 3, in order to obtain compensation performance equivalent to the adaptive recording compensation table in the case of d = 1 shown in FIG. 4A, the adaptive recording compensation table is as shown in FIG. 4B. As shown in this figure, the number of patterns of combinations of recording mark length and space length was 4 × 4 = 16 when d = 1, whereas 7 × when d = 3. 7 increases to 49. This is because the size of the adaptive recording compensation table (number of mark length and space length classification) is based on the distance affected by heat accumulation and thermal interference on the medium. This is because it is necessary to maintain the physical size of the table. That is, under the condition that the shortest mark length is the same, the channel bit length when d = 3 is ½ that when d = 1, and the range from 2T to 5T when d = 1 is d This corresponds to 4T, 5T, 6T, 7T, 8T, 9T, and 10T or more in the case of = 3.

  As described above, when an RLL code having a large shortest run length d is used to improve the linear recording density, the number of parameters constituting the adaptive recording compensation table increases. As a result, in addition to squeezing the limited recording area of the medium control information, it also becomes an issue that the time required for adjusting the values of many parameters increases.

  In the present invention, only some parameters (hereinafter referred to as default parameters) in the adaptive recording compensation table are given in advance, and other parameters (hereinafter referred to as undetermined parameters) are calculated by interpolation based on the default parameters to complete the table. I tried to make it.

  More specifically, it is as follows.

  (1) Among the correction parameters of the recording pulse waveform constituting the adaptive recording compensation table, the values of predetermined parameters, which are some correction parameters, are recorded in the medium control information recording area as part of the medium control information. An information recording medium characterized by

  This eliminates the need to record all parameters in the adaptive recording compensation table on the medium as a part of the medium control information, thereby suppressing an increase in the data amount of the medium control information. Even if d = 1, there is an effect that the data amount of the medium control information can be reduced, but the effect of reducing the data amount is remarkable particularly when an RLL code having a large shortest run length is used.

  (2) After the user data is modulated using the RLL code, NRZI conversion is performed, and the information is recorded on the information recording medium according to the adaptive recording compensation table in which the correction parameters of the recording pulse waveform are classified by the mark length and the space length. In the information recording method for recording, only the values of predetermined parameters, which are some correction parameters among the correction parameters of the recording pulse waveform constituting the adaptive recording compensation table, are used as part of the medium control information. The value of the predetermined parameter is read from the information recording medium recorded in the recording area, and the value of the undetermined parameter that is the remaining correction parameter in the adaptive recording compensation table is calculated by interpolation using the value of the predetermined parameter. The information recording method is characterized in that the table is completed.

  This configuration is a method for recording information on the information recording medium (1). With this configuration, even if only some correction parameters (predetermined parameters) are given among the correction parameters of the recording pulse waveform constituting the adaptive recording compensation table, the remaining correction parameters (undecided parameters) are set using the default parameters. Since the adaptive recording compensation table can be completed by calculation, information can be appropriately recorded on the information recording medium as described in (1) above.

  (3) In the adaptive recording compensation table, the interpolation method is a set of a predetermined parameter closest to the upward direction and a predetermined parameter closest to the downward direction from the undetermined parameter whose value is to be calculated, or closest to the left direction. The linear interpolation was performed using one of the set of the default parameter and the default parameter closest to the right direction.

  This configuration is a specific example of a method for calculating an undetermined parameter by interpolation of a predetermined parameter in the configuration (2). With this configuration, it is possible to easily calculate undetermined parameters and appropriately record information.

  (4) Using the RLL code having the shortest run length of d1, using the first linear velocity as the linear velocity, the first recording power as the recording power, and the first channel bit cycle T1 as the channel bit cycle. After determining the first correction value table, the RLL code having the shortest run length of d2 (d2> d1) is used, the linear velocity is the first linear velocity, and the recording power is the first recording power. The second correction value table obtained by interpolating the first correction value table using the second channel bit period T2 of T2 = (d1 + 1) / (d2 + 1) × T1 as the channel bit period. The information recording method described in (2) is characterized in that information is recorded on an information recording medium.

  This configuration is a specific method for determining the default parameters in the above (1) and (2). With this configuration, it is possible to determine a predetermined parameter that ensures a sufficient recording quality.

  (5) The information recording method according to (2), wherein a monopulse type recording strategy is used as the recording pulse waveform.

  In this configuration, the recording strategy used in the configuration (2) is specifically a monopulse type. In the monopulse type recording strategy, since there is one power level for forming marks for all mark lengths, it is possible to easily calculate undetermined parameters by interpolation of predetermined parameters in (2) above. it can.

  (6) After the user data is modulated using the RLL code, NRZI conversion is performed, and the information is recorded on the information recording medium according to the adaptive recording compensation table in which the correction parameters of the recording pulse waveform are classified by the mark length and the space length. In the information recording method for recording, only the values of predetermined parameters, which are some correction parameters among the correction parameters of the recording pulse waveform constituting the adaptive recording compensation table, are used as part of the medium control information. The value of the predetermined parameter is read from the information recording medium recorded in the recording area, and the value of the undetermined parameter that is the remaining correction parameter in the adaptive recording compensation table is calculated by interpolation using the value of the predetermined parameter. The table is completed, and the recording pulse according to the completed adaptive recording compensation table The information is recorded on the information recording medium using the shape, the recorded data is reproduced, it is judged whether the reproduction signal quality satisfies the predetermined standard, and if the standard is not satisfied, the default parameter is corrected. The quality evaluation method of the information recording medium is characterized in that quality evaluation is performed by recording and reproducing again.

  This configuration is a method for evaluating the quality of the information recording medium as described in (1) above. In the information recording medium (1), only some of the correction parameters constituting the adaptive recording compensation table are recorded. This configuration ensures that information can be recorded with high reliability even on such an information recording medium. This evaluation method is an appropriate method for determining whether the information medium to be evaluated has sufficient quality.

  According to the present invention, since the number of parameters to be recorded on the medium as the medium control information can be suppressed, an information recording medium having both large capacity and high reliability can be provided at low cost. In particular, by using an RLL code having a large shortest run length, when the number of recording pulse waveform correction parameters constituting the adaptive recording compensation table increases, an effect of significantly suppressing an increase in the data amount of the medium control information is obtained. is there.

The figure which showed an example of the recording strategy. The figure which showed an example of the adaptive recording compensation table. The figure which showed the mark length in case of the shortest run length d = 1 and 3. FIG. The figure which showed an example of the adaptive recording compensation table in case the shortest run length d = 1. The figure which showed an example of the adaptive recording compensation table in case the shortest run length d = 3. The figure which showed the data structure of the multilayer optical disk medium of this invention. The figure which showed the structure of the medium control information unit in the multilayer optical disk medium of this invention. The figure which showed an example of the method of calculating an undetermined parameter by interpolation of a predetermined parameter. The flowchart which showed the recording procedure. The flowchart which showed the determination procedure of the default parameter. The figure which showed the adaptive recording compensation table of this invention. The figure which showed the structural example of the optical disk apparatus to which this invention is applied. The flowchart which showed an example of the procedure which adjusts a correction parameter to an optimal value. The figure which showed the experimental result of the default parameter. The figure which showed the experimental result of the default parameter. The figure which showed an example of the recording pulse waveform in this invention. The flowchart which showed the quality evaluation procedure of the optical disk medium using this invention. The figure which showed an example of the method of calculating an undetermined parameter by interpolation of a predetermined parameter. The figure which showed an example of the method of calculating an undetermined parameter by interpolation of a predetermined parameter. The figure which showed an example of the method of calculating an undetermined parameter by interpolation of a predetermined parameter.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Device configuration>
FIG. 11 is a diagram showing a configuration example of an optical disc apparatus to which the present invention is applied. The optical disk medium 300 mounted on the apparatus is rotated by a spindle motor 360. At the time of recording, the recording encoding circuit 340 modulates user data to be recorded received from the host computer via the interface according to the RLL (3, 16) encoding rule, and converts the data into data that can be recorded on the optical disc medium 300. The laser driver 316 receives the encoded data from the encoding circuit 340 and converts it into a voltage waveform suitable for driving the laser driver 316 in the optical head 310. In the optical head 310, the received voltage waveform is converted into laser light by the semiconductor laser 312. During reproduction, the laser power / pulse controller 320 controls the current flowing to the semiconductor laser 312 via the laser driver 316 in the optical head 310 so that the light intensity commanded by the CPU 340 is generated, thereby generating laser light 314. The laser beam 314 is condensed by the objective lens 311 to form a light spot 301 on the optical disc medium 300. The reflected light 315 from the light spot 301 is detected by the photodetector 313 via the objective lens 311. The photodetector is composed of a plurality of photodetecting elements. The reproduction signal processing circuit 330 reproduces information recorded on the optical disc medium 300 using the signal detected by the optical head 310. The entire apparatus is controlled by the system controller 400.

  The reproduction signal processing circuit 330 generates a channel bit clock signal by performing processing such as a band limiting filter, an auto slicer, and a PLL (Phase Locked Loop) on the signal detected by the optical head 310, and binarizes the signal. A reproduction signal is generated. The edge shift detector 335 uses the channel bit clock signal and the binarized reproduction signal generated by the reproduction signal processing circuit 330 to calculate the time difference between the binarized reproduction signal and the channel bit clock signal at the reproduction signal edge as the channel bit. The value normalized by the clock cycle is measured as an edge shift. Further, the edge shift value at each measurement edge is classified by the combination of the mark length and the preceding space length or the combination of the mark length and the succeeding space length on the basis of the data pattern of the binarized reproduction signal. The average value of edge shift is calculated and output.

  Next, a configuration example of the laser power / pulse control unit 320 will be described. In this embodiment, a “monopulse type” recording strategy is used as the type of recording strategy. The monopulse type recording strategy is a method of recording using a single recording pulse regardless of the length of a mark to be recorded. FIG. 15 shows a recording pulse waveform for representatively forming 4T, 5T, 6T, and 7T marks among the 4T-17T marks constituting the RLL (3, 16) code used in this embodiment. It is a figure.

  The laser light output power levels Pw, Ps, and Pc are obtained by performing trial writing in a predetermined area on the optical disk medium using parameters related to OPC (Optimum Power Control) recorded in medium control information described later. Each is set to an optimum value.

  The mark edge shift due to the effect of thermal accumulation and thermal interference that occurs during recording is compensated by appropriately setting the correction parameters dTtop, dTc, and dTs of the recording pulse waveform. dTtop is a correction parameter for the timing of the start of the recording pulse, and is defined as the time difference between the start of the recording pulse and the start of the NRZI signal. DTc is a correction parameter for the timing of the end of the recording pulse, and is defined as the time difference between the end of the recording pulse and the end of the NRZI signal. DTs is a cooling pulse width correction parameter and is defined as a time difference between the end of the cooling pulse and the end of the NRZI signal. The polarities of the values of dTtop, dTc, and dTs are all defined as positive on the right side of the drawing.

  The values of these correction parameters dTtop, dTc, and dTs are classified into patterns of combinations of recording mark lengths and preceding or following space lengths for adaptive recording compensation, and are set individually. FIG. 10 is an adaptive recording compensation table for dTtop, dTc, and dTs. The value of dTtop is classified by a combination of the recording mark length and the preceding space length, and dTc and dTs are classified by a combination of the recording mark length and the following space length. The recording mark length and the space length are classified into 7 types of 4T, 5T, 6T, 7T, 8T, 9T, and 10T or more, and the values of the correction parameters dTtop, dTc, and dTs are 7 as combinations thereof, respectively. × 7 = 49 categories are set and set. The sizes (the number of correction parameters) of these adaptive recording compensation tables are determined to be a necessary and sufficient size based on the range affected by heat accumulation and thermal interference in the recording film of the optical disc medium 300.

  Next, a method for adjusting each correction parameter to an optimum value in the adaptive recording compensation table will be described. FIG. 12 is a flowchart showing an example of the procedure. Here, a method of adjusting the value of the correction parameter dTtop for the timing of the recording pulse start end is shown, but the same procedure can be applied to other correction parameters (dTc, dTs). First, in step S121 after the start of the procedure, each value of dTtop classified by a combination pattern of mark length and preceding space length (7 × 7 = 49) is set. Here, a predetermined initial value is set when the step S121 is executed for the first time, and those values are updated after the second time. Next, random data is recorded under the conditions of a pulse correction parameter and a predetermined power level (step S122). Next, the recorded data is reproduced, and the reproduction signal processing circuit 330 generates a channel bit clock signal and a binary reproduction signal (step S123). Next, using the generated channel bit clock signal and the binarized reproduction signal, the edge shift is measured by the edge shift detector 335, classified by the combination pattern of the mark length and the preceding space length, and the respective edge shifts. A value is calculated (step S124). It is determined whether or not the absolute value of each edge shift is minimum (step S125). If it is minimum (Yes), the process ends. If there is a non-minimum parameter (No), the process returns to step S121 and the correction parameter is corrected. Update the set value and repeat the same procedure.

<Media and media control information>
FIG. 5 is a diagram showing a data structure of the optical disc medium 300 of the present invention. In the optical disk medium 300, a lead-in area 101, a data area 102, and a lead-out area 103 are arranged in order from the inner periphery of the disk, and the medium control information 104 is described in the lead-in area 101. In the medium control information 104, medium control information units 0, 1, 2,..., N−1 classified into N types according to the combination of the recording layer, the recording speed, and the recording strategy type are sequentially described. . In this specification, one set of medium control information classified and given according to conditions is referred to as a medium control information unit in this specification.

  FIG. 6 is a diagram showing the structure of the medium control information unit. One medium control information unit is composed of 112-byte data including header information 201, recording / playback control information 202, and footer information 203. The header information 201 includes the number of medium control information units, the type of recording pulse used at the time of recording, or information on the recording layer to which the medium control information unit is applied. The contents of the recording / reproduction control information 202 are divided into medium information 204, reproduction power setting information 205, recording power setting information 206, and recording pulse setting information 207, and parameters necessary for recording or reproduction are described for each item. The For example, the reproduction power setting information 205 includes maximum reproduction power information that specifies an upper limit value of the power applied to the medium when information is reproduced. In the recording power setting information 206, a value of a parameter for performing optimization adjustment of each power level at the time of recording called OPC (Optimum Power Control) is described. The recording pulse setting information 207 describes values of correction parameters dTtop, dTc, and dTs of the recording pulse waveform constituting the adaptive recording compensation table.

  Here, details of the correction parameters described in the recording pulse setting information 207 will be described. The table on the left side of FIG. 7 shows an adaptive recording compensation table for the correction parameter dTtop. Of the 7 × 7 = 49 parameters constituting the adaptive recording compensation table, only 16 parameters marked with symbols A to P in the table on the left side of FIG. 7 are described in the recording pulse setting information 207. is there. Other shaded parameter values are not described in the medium control information 207. Specifically, it is a combination pattern in which the mark length and the preceding space length are both 4T, 6T, 8T, or 10T or more. DTc and dTs are basically the same except that they are classified according to the subsequent space length instead of the preceding space length. In the present specification, the parameters described in the recording pulse setting information 207 are hereinafter referred to as “predetermined parameters”, and the other parameters not described in the medium setting information 207 are referred to as “undecided parameters”.

<Method for completing the adaptive recording compensation table>
A method for determining the value of the undetermined parameter not given by the medium control information and completing the adaptive recording compensation table will be described. In this embodiment, the undetermined parameter is calculated by performing interpolation using a predetermined parameter. The left side of FIG. 7 shows an adaptive recording compensation table of the correction parameter dTtop at the recording pulse start end. As described above, among the 7 × 7 = 49 parameters necessary for determining the recording pulse waveform, the recording pulse setting information 207 describes that both the mark length and the leading space length are 4T, It is only the parameter of the combination pattern which is either 6T, 8T, or 10T or more.

  Here, in order to simplify the notation of the pattern of the combination of mark length and space length, for example, a 4T mark is represented as “4M”, a 5T space is represented as “5S”, the mark length is 4T, and the preceding space length is A pattern that is 5T is expressed as “5S4M”.

  The table on the right side of FIG. 7 is a diagram showing only the 3 × 3 pattern portion at the upper left of the table for explanation. In this part, 4S4M, 4S6M, 6S4M, and 6S6M patterns are the default parameters, and their values are A, B, E, and F, respectively. Other parameters are undetermined parameters.

  To calculate the value of an undetermined parameter, a set of the default parameter closest to the top of the table and the default parameter closest to the bottom from the undetermined parameter to be calculated, or the default parameter closest to the left and the right Linear interpolation is performed using one of a set of predetermined parameters closest to the direction. For example, to determine the undetermined parameters of 4S5M, a set of default parameters of 4S4M and 4S6M is used. Since the mark length of 4S5M is 5T and is exactly halfway between the mark length of 4S4M (4T) and the mark length of 6S6M (6T), the parameter value of 4S5M is the value of 4S4M (= A) and the value of 4S6M (= B ) Average value. Therefore, (A + B) / 2. If this is expressed in a generalized manner, a value y of an undetermined parameter whose mark length (or space length) is x is a set of a default parameter of mark length x1 and value y1, and a default parameter of mark length x2 and value y2. , The value y of the undetermined parameter is

It becomes. Similarly, the value of the undetermined parameter of 5S4M becomes (A + E) / 2 by performing linear interpolation using the default parameters of 4S4M and 6S4M. In this way, the values of the undetermined parameters of 5S6M and 6S6M are also calculated, respectively. Finally, the value of 5S5M is linearly interpolated using the parameters of 4S5M and 6S5M that have been known by the above calculation (A + B + E + F) / 4. In this way, the adaptive recording compensation table is completed by calculating the values of all undetermined parameters. Further, similarly, by completing the adaptive recording compensation table for dTc and dTs, the recording pulse waveform for recording is determined.

  FIG. 8 is a flowchart showing an example of a recording procedure including the completion of the adaptive recording compensation table. After starting the procedure, first, the medium control information 104 is read out from the lead-in area 101 of the optical disc 300, and dTtop, dTc, and dTs specified in the recording pulse setting information 207 of the recording / playback control information 202 of the corresponding medium control information unit are preset. Get each parameter. (Step S801). Subsequently, the undetermined parameter is calculated by performing linear interpolation using the predetermined parameter by the above-described method, and the table is completed (step S802). Finally, a recording pulse waveform is set according to the completed adaptive recording compensation table, and information is recorded on the optical disc (step S803).

  An example of a method for determining the default parameter described in the recording pulse setting information 207 in the medium control information will be described. As described above, the default parameters shown on the left side of FIG. 7 are classified into four types of mark length and space length of 4T, 6T, 8T, and 10T or more, respectively, and are given for each combination pattern. Here, referring to FIG. 3, under the condition that the physical length of the shortest mark is the same, the lengths of the 4T, 6T, 8T, and 10T marks when d = 3 are d = 1. It can be seen that the lengths of the 2T, 3T, 4T, and 5T marks are the same. Therefore, if recording / reproduction is performed using the RLL code of d = 1 and the values of the parameters in the adaptive recording compensation table shown in FIG. 4A are determined so that the signal quality satisfies a predetermined standard, they are represented by d = 3 can be used as a default parameter when an RLL code of 3 is used.

  FIG. 9 is a flowchart showing a procedure for determining a predetermined parameter in the present embodiment. After starting the procedure, recording / reproduction is first performed using an RLL code of d = 1, and each correction parameter in the adaptive recording compensation table of dTtop, dTc, and dTs is set so that the signal quality satisfies a predetermined standard. The value is adjusted to the optimum value (step S901). The result of an experiment in which this was actually performed and the correction parameters were determined is shown on the left of FIG. Here, the value of each correction parameter is an integer value in units of 1/32 of the channel bit period Tw. Subsequently, each parameter value determined for d = 1 is applied to the default parameter for d = 3. At this time, the mark length and the space lengths 2T, 2T, 4T, and 5T or more when d = 1 correspond to 4T, 6T, 8T, and 10T or more when d = 3, respectively (step S902). The result of actually doing this is shown on the right in FIG. Here, the value of each correction parameter is an integer value in units of 1/16 of the channel bit period Tw. In this way, the integer value given to the table with d = 1 can be applied as it is to the default parameter value of the table with d = 3. Subsequently, the undetermined parameter is determined by interpolation using the predetermined parameter, and the table is completed (step S903). The interpolation method at this time is as shown in the third embodiment. The result of actually doing this is shown on the right in FIG. Here, if the value of the undetermined parameter calculated by linear interpolation does not become an integer, it is converted to an integer by rounding off the decimals. The integerization here may be performed by other methods, for example, rounding up or rounding off may be used.

  The shortest run length d1 of the modulation code used for determining the predetermined parameter and the shortest run length d2 of the modulation code used for recording user data are d2 + 1 = n (d1 + 1) (where n is an integer of 2 or more). It is desirable to satisfy. In this case, assuming that the physical length of the shortest mark is the same, all the marks in the modulation code used for determining the predetermined parameter have the same length as that of the modulation code used for recording user data. It must be present in the mark. As a result, the predetermined parameter determination flow can be easily performed. Also in the present embodiment, modulation codes of d1 = 1 and d2 = 3 (n = 2 at this time) satisfying this relationship are used.

  A medium quality evaluation method using the present invention will be described. The purpose of this is to ensure the reliability of information recording for an optical disc medium in which only a part of the correction parameters constituting the adaptive recording compensation table is recorded as medium control information. It is assumed that the default parameter value is used as a means for confirming whether the value is appropriate. FIG. 16 is a flowchart showing an example of a medium quality evaluation procedure. In this procedure, a step of determining the medium quality is added to the end of the recording procedure in the second embodiment. Steps S1601 to S1603 are the same as steps S801 to S803 in the above embodiment. Subsequently, the recorded data is reproduced, and it is determined whether the reproduction signal quality satisfies a predetermined standard (step S1604). If the standard is satisfied (Yes), it is determined that there is no problem in the quality of the optical disk medium, and the procedure is terminated. On the other hand, if the standard is not satisfied (No), the default parameter is corrected (step S1605), and the process returns to step S1601 and the same procedure is repeated. Here, the determination of the reproduction signal quality in step S1604 is performed using a reproduction signal quality evaluation index corresponding to the PRML system. As an evaluation index of the reproduction signal quality corresponding to the PRML system, the probability Pa corresponding to the most probable state transition sequence and the probability Pb corresponding to the second most probable state transition sequence are used, and | Pa−Pb | The quality of the reproduced signal is evaluated based on the distribution of. Alternatively, a pattern including a virtual 1T run length is used as an error pattern in which the edge portion of the reproduction signal shifts to the left and right, and the difference in signed sequence error is obtained based on the edge shift direction, and the edge shift amount is calculated. Reproduction signal evaluation technology is used.

  Next, another embodiment of the adaptive recording compensation table will be described. The table on the left of FIG. 17 is an adaptive compensation table for the correction parameter dTtop in the present embodiment. Of the 7 × 7 = 49 parameters constituting the adaptive recording compensation table, 9 parameters with symbols A to I are default parameters. Specifically, it is a combination pattern in which the mark length and the preceding space length are both 4T, 7T, or 10T or more. In other words, the default parameter is given for a pattern of combinations of mark length and preceding space length every 2T. The advantage of this configuration is that the number of default parameters is reduced compared to the configuration of the first embodiment, that is, the default parameters are given to a combination pattern of mark length and preceding space length every 1T. The amount of control information can be further reduced.

  The procedure for determining the value of the undetermined parameter in this configuration and completing the adaptive recording compensation table is as follows. The table on the right side of FIG. 17 is a diagram showing only the 5 × 5 pattern portion at the upper left of the table for explanation. In this part, the 4S4M, 4S7M, 7S4M, and 7S7M patterns are the default parameters, and their values are A, B, D, and E, respectively. Other shaded parameters are undetermined parameters. The value of the undetermined parameter is calculated by linear interpolation using a predetermined parameter, as in the configuration of the third embodiment. Specifically, from the undetermined parameter whose value is to be calculated, a set of the default parameter closest to the top of the table and the default parameter closest to the bottom, or the default parameter closest to the left and the default closest to the right Linear interpolation is performed using any one of a pair with a parameter. In the case of linear interpolation, the value y of the undetermined parameter whose mark length (or space length) is x as described above is that the mark length of one default parameter is x1, the value is y2, and the mark length of the other default parameter is Since x2 and y2 are given by Equation 1, for example, using the predetermined parameter values A and B of 4S4M and 4S7M, the values of the undetermined parameters of 4S5M and 4S6M are (2A + B) / 3, respectively. And (A + 2B) / 3. Similarly, the values of the undetermined parameters of 5S4M, 5S7M, 6S4M, 6S7M, 7S5M, and 7S6M are calculated, respectively, and the values of the undetermined parameters of 5S5M, 5S6M, 6S5M, and 6S6M are subsequently calculated using the values of the undetermined parameters. calculate. The values of the undetermined parameters are as shown in the table on the right side of FIG. In this way, the adaptive recording compensation table is completed by calculating the values of all undetermined parameters in the table.

  The procedure for calculating the undetermined parameter in the adaptive recording compensation table for dTc and dTs is the same as the above procedure except that it is classified by the subsequent space length instead of the preceding space length.

  In this embodiment, all the default parameters are given every 2T. However, they may be mixed every 1T and every 2T. Especially, in the long mark / long space region, they are provided every 3T. It doesn't matter.

  Next, still another embodiment of the adaptive recording compensation table will be described. The table on the left side of FIG. 18 is an adaptive compensation table for the correction parameter dTtop in the present embodiment. Of the 7 × 7 = 49 parameters constituting the adaptive recording compensation table, the default parameters are 18 with the symbols A to P, Q and R. This is obtained by adding 4S5M and 5S4M as the default parameters to the default parameters in the configuration of the first embodiment. This configuration corresponds to the case where the value of the parameter in the adaptive recording compensation table changes nonlinearly with respect to the mark length or space length. This non-linearity is particularly likely to occur in the region where the mark length and space length relative to the light spot diameter are small, and the value of the undetermined parameter calculated by linear interpolation deviates relatively from the ideal value according to the characteristics of the medium. There is a case. Therefore, in this configuration, a parameter related to the 5T mark or 5T space is also set as a default parameter, and the value is described in the medium control information. The method for calculating the value of the undetermined parameter is the same as that in the configuration of the first embodiment. In this configuration, 4S5M and 5S4M are just examples of additional default parameters, and other patterns may be added as default parameters according to the characteristics of the recording medium to be used. However, in view of the purpose of the present embodiment described above, it is desirable to add sequentially from a combination pattern of a short mark length and a short space length.

  The procedure for calculating the undetermined parameter in the adaptive recording compensation table for dTc and dTs is the same as the above procedure except that it is classified by the subsequent space length instead of the preceding space length.

  Next, still another embodiment of the adaptive recording compensation table will be described. The table on the left side of FIG. 19 is an adaptive compensation table for the correction parameter dTtop in the present embodiment. Of the 7 × 7 = 49 parameters constituting the adaptive recording compensation table, the default parameter is 16 with the symbols A to P, that is, the mark length and the leading space length are both 4T, 6T, 8T, or 10T. Any of the above is a combination pattern, and the other shaded parameters are undetermined parameters. This is the same as the configuration of the first embodiment, and the calculation method of the undetermined parameter value is basically the same as the configuration of the first embodiment. The difference between this configuration and the configuration of the first embodiment is in the calculation formulas of the undetermined parameter values of 4S5M and 5S4M. Specifically, as shown in the table on the right side of FIG. 19, the interpolation formula for calculating the value of the undetermined parameter of 4S5M is (A + 2B) / 3 using the default parameter values A and B of 4S4M and 4S6M. It becomes. Further, the interpolation formula for calculating the value of the undetermined parameter of 5S4M is (A + 2E) / 3 using the default parameter values A and E of 4S4M and 6S4M. Similar to the configuration of the fifth embodiment, this configuration corresponds to the case where the parameter value in the adaptive recording compensation table changes nonlinearly with respect to the mark length or the space length. However, in this configuration, instead of adding the parameters related to the short mark length and short space length, which are easily affected by nonlinearity, to the default parameters, the values are calculated using interpolation formulas that are weighted differently from those of other parameters. I am trying to calculate. As a result, it is possible to cope with the non-linearity without increasing the number of predetermined parameters, so that an increase in the data amount of the medium control information can be suppressed. It should be noted that the weighting method in the configuration of this embodiment is merely an example, and it is of course possible to use an interpolation formula with a different weight depending on the characteristics of the recording medium to be used.

  The procedure for calculating the undetermined parameter in the adaptive recording compensation table for dTc and dTs is the same as the above procedure except that it is classified by the subsequent space length instead of the preceding space length.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, in the above embodiment, the monopulse type recording strategy is used. However, the present invention can be similarly applied to other recording strategies such as a multi-pulse type, a castle type, or an L type. it can.

300: optical disc 301: light spot 310: optical head 311: objective lens 312: semiconductor laser 313: photodetector 314: laser light 315: reflected light 316: laser driver 320: laser power / pulse controller 330: reproduction signal processor 335: Edge shift detector 340: CPU
345: Coding circuit 360: Spindle motor 400: System controller

Claims (13)

An information recording area for recording information using a recording pulse waveform;
And at least a medium control information recording area in which correction parameters of the recording pulse waveform are recorded,
In the medium control information recording area, values of predetermined parameters that are some of the correction parameters are recorded as part of the medium control information, and some of the other correction parameters are recorded. An information recording medium characterized in that the value of the correction parameter is not recorded.   2. The information recording medium according to claim 1, wherein the values of the other correction parameters are calculated using the recorded values of the correction parameters.   The value of the other partial correction parameter is a set of a preset parameter closest to the upper direction and a default parameter closest to the lower direction among the recorded correction parameter values, or a default parameter closest to the left direction. 3. The information recording medium according to claim 2, wherein the information recording medium is calculated by linear interpolation using any one of a pair of a predetermined parameter closest to the right direction. Information that records user information on an information recording medium in accordance with an adaptive recording compensation table in which user data is modulated using an RLL code, NRZI converted, and recording pulse waveform correction parameters are classified by mark length and space length. In the recording method,
Of the correction parameters of the recording pulse waveform constituting the adaptive recording compensation table, information parameters in which the values of predetermined parameters, which are some correction parameters, are recorded in the medium control information recording area as part of the medium control information Reading a value of the predetermined parameter from the medium, and calculating a value of an undetermined parameter that is a remaining correction parameter in the adaptive recording compensation table by interpolation using the value of the predetermined parameter;
And a step of generating the recording pulse waveform using at least the calculated parameter value and recording the user data on the information recording medium.   In the adaptive recording compensation table, the interpolation method includes a set of a default parameter closest to the upward direction and a default parameter closest to the downward direction from a undetermined parameter whose value is to be calculated, or a default parameter closest to the left direction. 5. The information recording method according to claim 4, wherein linear interpolation is performed using any one of a set with a predetermined parameter closest to the right direction.   5. The information recording method according to claim 4, wherein at least a part of the adaptive recording compensation table is provided for a pattern in which the predetermined parameter is a combination of a mark length and a preceding space length every 1T.   5. The information recording method according to claim 4, wherein at least a part of the adaptive recording compensation table is provided for a pattern in which the predetermined parameter is a combination of a mark length and a preceding space length every 2T.   The adaptive recording compensation table indicates that the number of the predetermined parameters of the combination pattern of the short mark length and the short leading space length is larger than the number of the predetermined parameters of the combination pattern of the long mark length and the long leading space length. 5. The information recording method according to claim 4, wherein:   In the adaptive recording compensation table, the interpolation formula for calculating the undetermined parameter of the combination pattern of the short mark length and the short preceding space length is an interpolation for calculating the undetermined parameter of the combination pattern of the long mark length and the long preceding space length. 5. The information recording method according to claim 4, wherein the information recording method is different from the equation. The RLL code having the shortest run length of d1 is used, the first linear velocity is used as the linear velocity, the first recording power is used as the recording power, and the first channel bit cycle T1 is used as the channel bit cycle. After determining the correction value table,
The RLL code having a shortest run length of d2 (d2> d1) is used, the linear velocity is the first linear velocity, the recording power is the first recording power, and the channel bit period is T2 = (d1 + 1) / Recording information on the information recording medium using the second correction value table obtained by interpolating the first correction value table using the second channel bit period T2 of (d2 + 1) × T1. The information recording method according to claim 4.   5. The information recording method according to claim 4, wherein a monopulse type recording strategy is used as the recording pulse waveform. User data is modulated using an RLL code, NRZI-converted, and information is recorded on an information recording medium according to an adaptive recording compensation table in which correction parameters of the recording pulse waveform are classified by mark length and space length, In a method for evaluating the quality of a medium by reproducing the recorded information,
Of the correction parameters of the recording pulse waveform constituting the adaptive recording compensation table, information parameters in which the values of predetermined parameters, which are some correction parameters, are recorded in the medium control information recording area as part of the medium control information Reading a value of the predetermined parameter from the medium, and calculating a value of an undetermined parameter that is a remaining correction parameter in the adaptive recording compensation table by interpolation using the value of the predetermined parameter;
Using at least the calculated parameter value to generate the recording pulse waveform and recording information on the information recording medium;
A method for evaluating the quality of the information recording medium, comprising: reproducing the recorded information and evaluating the quality of the reproduced signal.   13. The method according to claim 12, wherein when the reproduction signal quality does not satisfy a predetermined criterion, the default parameter is corrected, and the process returns to the step of calculating the value of the undetermined parameter using the corrected default parameter. A method for evaluating the quality of the described information recording medium.

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