JP2005339758A - Information recording method, information recording device, optical disc, program, and computer-readable recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decide an optimal recording power and an optimal recording pulse width regardless of the optical disc and device individual differences and the environmental condition in a multi-value recording method. <P>SOLUTION: The method includes: a first step (steps S2 to S8) for successively changing the top pulse width Ton for test-recording first test data and monitoring the reflected light intensity corresponding to the data; a second step (steps S9 to S11) for deciding an optimal top pulse width Ton from the monitoring result; a third step (steps S13, S14) for deciding an optimal off pulse width Toff corresponding to the multi-value data from the monitoring result at the optimal top pulse width Ton decided; and a fourth step (steps S15 to S23) for using the decided optimal top pulse width Ton and the optimal off pulse width Toff so as to successively change the recording power, test-record second test data, monitor the reflected light intensity corresponding to the data, and decide the optimal recording power from the monitoring result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information recording method, an information recording apparatus and an optical disc for recording a recording mark according to multi-value data on an optical disc such as a rewritable phase change type optical recording medium, and a computer to execute the information recording method. And a computer-readable recording medium on which the program is recorded.

  In recent years, with the advancement of digital technology and the improvement of data compression technology, CD-ROM and CD-ROM have been used as media for recording information (hereinafter also referred to as “content”) such as music, movies, photographs, and computer software. DVD-ROM and other optical discs that can record about 7 times the data on a disc with the same diameter as a CD-ROM have been attracting attention, and at the same time, the content recorded on the optical disc is played back. The optical disk device to be used became popular.

  A reproduction-only optical disk such as a CD-ROM or DVD-ROM has a spiral or concentric pit string formed on the recording surface. Information is recorded by the length of pits, the length between pits, and combinations thereof. In this case, the information is converted (binarized) into a combination of two types of numerical values (binary) of 0 and 1, and written on the optical disc. Hereinafter, such a recording method is referred to as a binary recording method.

  By the way, the information amount of the content tends to increase year by year, and a further increase in the amount of information that can be recorded on the optical disc is expected. One way to increase the amount of information that can be recorded on an optical disc is to convert the information into a combination of three or more numerical values and write it to the optical disc. Has been done. Therefore, for the sake of convenience, converting information into a combination of three or more types of numerical values is hereinafter referred to as multi-value data, and multi-value data is referred to as multi-value data. In addition, such a recording method for recording information with multiple values is called a multi-value recording method.

  In addition, regarding recording on a rewritable optical disc, there is an influence of individual differences between the optical disc and the optical disc apparatus and usage environment conditions, so it is necessary to optimize the recording conditions in each combination. For example, in the case of a phase change optical disc, the emission time width, recording power, and erasing power of the recording laser are controlled in order to form a desired recording mark.

According to Patent Document 1 for multi-value data recording, in order to reliably reproduce multi-value recorded data, test writing is performed and test recording is performed until a desired reproduction signal is obtained. ing. And recording correction (correction of recording conditions)
(1) Record and play back test data
(2) Compare ideal waveform and playback signal waveform
(3) Has it converged? If yes, exit
(4) If NO, correct laser irradiation conditions
(5) The procedure returns to (1).

Here, the multilevel recording method to which the present invention is applied will be described with reference to FIG. Recording is performed for each recording cell having a certain length on the recording track so that the reproduction signal level changes corresponding to the multilevel data. For reproduction of multi-value data, the reproduction signal is sampled at a predetermined frequency (for example, the center position of the recording cell), and the multi-value data is discriminated from the sampled reflected light intensity. Since the spot diameter of the reproduction light is longer than the circumferential length of the recording cell, intersymbol interference occurs. In the prior art, multi-level data can be accurately determined by performing the above-described recording correction in consideration of this intersymbol interference. In the case of 8-level recording, there are 8 ³ = 512 combinations of multi-value data to be considered. Therefore, it takes a lot of time to optimize the recording conditions.

  In this regard, Patent Document 2 proposes a recording method in which optimum recording conditions (recording power and recording pulse width) can be determined by a simple method without performing complicated processes as in Patent Document 1. In this patent document 2, regarding the recording power, the recording power at which the reflected light intensity is saturated is set as the optimum recording power. On the other hand, regarding the pulse width, the pulse width at which the reflected light intensity is saturated is set as the optimum pulse width. Is used to determine the pulse width of other multi-value data. The pulse width in this proposed example is defined as the ratio of the sum of the top pulse width Ton and the off pulse width Toff to the cell time width Tc (see FIG. 1).

  However, it has been found that the optimum pulse width cannot be determined by the method disclosed in Patent Document 1, even though the optimum recording power can be determined. This problem will be described below.

  What is determined in the proposed example is (top pulse width Ton + off pulse width Toff) / cell time width Tc (hereinafter referred to as ξ), and each pulse width is not specified. There are many combinations of the top pulse width Ton and the off pulse width Toff at which the ratio ξ is equal, and each cannot be uniquely determined. Further, it has been found that these combinations affect the quality of the reproduction signal, and there is a problem that the multi-value data cannot be reproduced accurately unless an appropriate combination is selected.

  Specifically, as shown in FIG. 13, when the top pulse width Ton is increased, a large amount of heat is applied to the disk surface, so that the mark width in the radial direction is increased, and the signal from the recording mark in the adjacent track is reproduced. Crosstalk occurs in which are superimposed. In addition, a cross erase that erases a part of the mark recorded in the adjacent track occurs. These cause the reflected light intensity to fluctuate. Therefore, in the multi-value recording in which the multi-value data is determined from the reflected light intensity, there arises a problem that the recorded data cannot be reproduced accurately.

  In any case, since the optimum value of the combination of the top pulse width and the off pulse width varies depending on the individual difference between the optical disc and the optical disc apparatus and the change in the use environment, it is necessary to optimize the user data before recording.

  An object of the present invention is to determine an optimum recording power and an optimum recording pulse width (top pulse width and off-pulse width) in a multi-value recording system regardless of individual differences of optical disks and information recording apparatuses and changes in environmental conditions. It is to be.

  It is another object of the present invention to provide an optimum recording pulse width (top pulse width and off pulse width) with an excessive resolution regardless of individual differences of optical disks and information recording devices and changes in environmental conditions in a multi-level recording system. In other words, it is possible to record a record mark row that can reproduce an optimum reflected light intensity level with a simple configuration without using a pulse width generation circuit.

  Another object of the present invention is to enable stable recording without being affected by individual differences of optical disks and information recording apparatuses and usage environments.

  A further object is to enable stable recording to be performed in a short time without being affected by individual differences of optical discs and information recording apparatuses and usage environments.

  A further object is to provide an optical disc capable of setting an initial value in test recording.

  According to the first aspect of the present invention, there is provided an information recording method for recording a recording mark corresponding to multi-value data on an optical disk with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse. The first step of sequentially recording the first test data by changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data, and the optimum top pulse from the monitoring result A second step for determining the width Ton, a third step for determining the optimum off-pulse width Toff corresponding to the multi-value data from the monitoring result at the optimum top pulse width Ton determined in the second step, and the second step , Using the optimum top pulse width Ton and optimum off-pulse width Toff determined in the third step, the recording power is sequentially changed. The second test data to test recording, monitoring the reflected light intensity corresponding to the second test data comprises a fourth step of determining the optimum recording power from the monitor result.

  According to a second aspect of the present invention, in the information recording method of the first aspect, in the second step, the shortest top pulse width Ton at which the reflected light intensity monitored reaches the saturation value is determined as the optimum top pulse width.

According to a third aspect of the present invention, in the information recording method according to the first aspect, in the second step, the relational expression between the off-pulse width Toff and the reflected light intensity I with respect to each top pulse width Ton from the monitored result I = a · Toff ³ + b · Toff ² + c · Toff + d
And the top pulse width Ton that minimizes the absolute value of the coefficient c is determined as the optimum top pulse width.

According to a fourth aspect of the present invention, in the information recording method of the first aspect, in the third step, the off-pulse width when test recording the multi-value data m is Toff (m), and the reflected light intensity at this time is I ( m), when the coefficient is α, the optimum off-pulse width Toff opt (m) corresponding to the multi-value data m is expressed by the relational expression Toff opt (m) relating to the reflected light intensity L (m) that is the target value of the multi-value data m. ) = Α · (I (m) −L (m)) / (I (m + 1)
−I (m)) / (Toff (m + 1) −Toff (m)) + Toff (m)
Use to set.

According to a fifth aspect of the present invention, in the information recording method of the first aspect, in the third step, the optimum off-pulse width Toff (m) corresponding to the multi-value data m is set to the off-pulse width Toff (m) and the reflected light intensity I. Relational expression with (m) I (m) = a · Toff (m) ³ + b · Toff (m) ² + c · Toff (m) + d
Use to set.

According to a sixth aspect of the present invention, in the information recording method of the first aspect, in the first step, from the monitored result, the relational expression between the off pulse width Toff and the reflected light intensity I for each top pulse width Ton I = a · Toff ³ + b · Toff ² + c · Toff + d
And the coefficients a, b, c, d are approximated as a function of the top pulse width Ton, the Toff-reflected light intensity curve at the top pulse width Ton is predicted, and the shortest top pulse at which the reflected light intensity I becomes a saturation value. The width Ton is determined as the optimum top pulse width.

According to a seventh aspect of the present invention, in the information recording method of the first aspect, in the first step, from the monitored result, the relational expression between the off pulse width Toff and the reflected light intensity I for each top pulse width Ton I = a · Toff ³ + b · Toff ² + c · Toff + d
And the coefficients a, b, c, and d are approximated as a function of the top pulse width Ton, the Toff-reflected light intensity curve at the top pulse width Ton is predicted, and the off-pulse width Toff and the reflected light intensity I are approximately linear. The top pulse width Ton is set for each multi-value data.

  According to an eighth aspect of the present invention, in the information recording method according to any one of the first to seventh aspects, in the fourth step, the recording power is such that test recording is performed after setting the recording pulse, and the deviation of the reflected light intensity I is minimized. Is determined as the optimum recording power.

  The invention according to claim 9 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erase pulse. In this case, the top pulse width Ton (m) and the off pulse width Toff (m) corresponding to the multi-value data m are both set to be an integral multiple of the unit time T.

  According to the tenth aspect of the present invention, there is provided an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erase pulse. In this case, the off pulse width Toff is an integral multiple of the unit time T, and is increased substantially linearly as the recording mark increases.

  According to an eleventh aspect of the present invention, there is provided an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erase pulse. The off-pulse width Toff is an integral multiple of the unit time T and increases substantially linearly as the recording mark increases, and the top pulse width Ton is an integral multiple of the unit time T. The time is changed to a predetermined time according to the increase in the number of recording marks corresponding to.

  According to a twelfth aspect of the present invention, in the information recording method according to any one of the ninth to eleventh aspects, the top of the multilevel data is recorded with respect to a recording mark whose reflected light intensity is from a substantially intermediate level to a maximum level. In addition to increasing the pulse width Ton, the recording pulse is set so that the top pulse width Ton is substantially the same time for the recording mark whose reflected light intensity shows the minimum level from the intermediate level.

  According to a thirteenth aspect of the present invention, in the information recording method according to any one of the ninth to twelfth aspects, when the multi-value data m is an integer value greater than or equal to 0 that increases with an increase in recording marks, the top pulse width The top pulse width Ton (m) = j × Tc with respect to a unit time obtained by dividing Ton (m) and the off-pulse width Toff (m) by dividing the cell period Tc that is the period of the recording mark into n equal parts (n is a fixed value). / N (j is an integer value) and off pulse width Toff (m) = k × Tc / n (k is an integer value) is set, and the top pulse coefficient j is increased substantially linearly. The off-pulse coefficient k is increased for the recording mark whose reflected light intensity shows the maximum level from the substantially intermediate level in the multi-value data, and from the intermediate level to the recording mark whose reflected light intensity shows the minimum level. On the other hand, the same value was set.

  According to a fourteenth aspect of the present invention, in the information recording method according to any one of the ninth to thirteenth aspects, the period Tc / C is set so that the reflected light intensity from the optical disk corresponding to the multi-value data m becomes a desired level. A top pulse coefficient j and an off pulse coefficient k corresponding to an integer multiple of n are selected.

  The invention according to claim 15 is the information recording method according to any one of claims 9 to 14, wherein the multi-value data m is an integer value greater than or equal to 0 that increases with an increase in the recording mark. For the recording mark whose reflected light intensity shows the minimum level in the data, the top pulse coefficient j is set to be increased.

According to a sixteenth aspect of the present invention, there is provided an information recording method for recording a recording mark corresponding to multi-value data on an optical disk with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse. When the top pulse width Ton and the off pulse width Toff corresponding to multi-value data are set, the spot diameter (relative intensity 1 / e ² ) on the recording layer used for recording / reproduction is set for each multi-value data with respect to the cell length. When the recording mark length is less than or equal to a predetermined value, the top pulse width Ton is increased for recording marks having a predetermined value or more.

  According to a seventeenth aspect of the present invention, in the information recording method according to the sixteenth aspect, the recording mark length corresponding to the multi-value data for increasing the top pulse width Ton is approximately 1 of the spot diameter on the recording layer used for recording and reproduction. / 4 or less.

  According to an eighteenth aspect of the present invention, in the information recording method according to any one of the first to sixteenth aspects, the target optical disc is a phase change optical recording medium.

  According to a nineteenth aspect of the present invention, in the information recording method according to the eighteenth aspect, the recording layer of the target phase change optical recording medium is made of Ag-In-Sb-Te.

  An invention according to claim 20 is an information recording apparatus for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse. The first means for successively recording the first test data by changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data, and the optimum top based on the monitoring result A second means for determining the pulse width Ton, and a third means for determining the optimum off-pulse width Toff corresponding to the multi-value data from the monitoring result at the optimum top pulse width Ton determined by the second means, Using the optimum top pulse width Ton and the optimum off-pulse width Toff determined by these second and third means, the recording power is sequentially changed to obtain the second Strike data and test recording, monitoring the reflected light intensity corresponding to the second test data comprises a fourth means for determining the optimum recording power from the monitor result.

  The invention according to claim 21 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erase pulse. A recording parameter comprising a recording power Pw pre-recorded on the optical disc, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. The first test data is test-recorded by sequentially changing the recording power using the first step of reading the data, the read top pulse width Ton, the off-pulse width Toff, and the ratio ε of the erasing power Pe and the recording power Pw. Based on the second step of monitoring the reflected light intensity corresponding to the first test data and the monitoring result, the optimum recording power -A third step of determining Pw.

According to a twenty-second aspect of the present invention, in the information recording method of the twenty-first aspect, in the third step, a relational expression I = a · m ² + b · m + c between the multi-value data m and the reflected light intensity I is obtained from the monitored result. Then, the recording power that minimizes the coefficient a is determined as the optimum recording power.

The invention according to claim 23 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse. A recording parameter comprising a recording power Pw pre-recorded on the optical disc, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. The first test data is test-recorded by sequentially changing the recording power using the first step of reading the data, the read top pulse width Ton, the off-pulse width Toff, and the ratio ε of the erasing power Pe and the recording power Pw. Based on the second step of monitoring the reflected light intensity corresponding to the first test data and the monitoring result, the optimum recording power And a fourth step of calculating a correlation coefficient r ² by obtaining a relational expression I = a · m + b between the multi-value data m and the reflected light intensity I from the monitor result at the optimum recording power. The fifth step of determining the linearity between the multi-value data m and the reflected light intensity I using the correlation coefficient r ² , and the first test data is test-recorded by sequentially changing the off-pulse width Toff, A sixth step of monitoring the reflected light intensity corresponding to the first test data, and a seventh step of determining an optimum off-pulse width Toff corresponding to the multi-value data from the monitoring result are provided.

The invention according to claim 24 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse and erase pulse. A recording parameter comprising a recording power Pw pre-recorded on the optical disc, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. From the monitoring result, the second step of reading the first test data by successively changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data From the third step of determining the optimum recording power and the monitor result at the optimum recording power, the multi-value data m and the reflected light intensity I Seeking relation I = a · m + b, determining a fourth step of calculating the square r ² of the correlation coefficient r, the linearity of the multi-valued data m and the reflected light intensity I with the r ² Using the optimum recording power determined in the fifth step and the third step, the top pulse width Ton is sequentially changed to test record the first test data, and the reflected light intensity corresponding to the first test data A sixth step for monitoring the optimum top pulse width from the monitoring result, a seventh step for determining the optimum top pulse width, and an optimum off pulse width corresponding to the multi-value data from the monitoring result for the optimum top pulse width determined in the seventh step. And an eighth step of determining each.

  The invention according to claim 25 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erase pulse. A recording parameter comprising a recording power Pw pre-recorded on the optical disc, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. The first test data is test-recorded by successively changing the top pulse width Ton and the off-pulse width Toff using the read recording power and ε, and the reflection corresponding to the first test data. Based on the second step of monitoring the light intensity and the monitoring result, the optimum top pulse width and optimum offset corresponding to the multi-value data are obtained. And a third step for determining each of the pulse widths.

  An invention according to claim 26 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power by using a recording pulse composed of a set of top pulse, off pulse and erase pulse. A recording parameter comprising a recording power Pw pre-recorded on the optical disc, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. The first test data is test-recorded by sequentially changing the off-pulse width Toff using the read recording power, ε, and top pulse width Ton, and the reflection corresponding to the first test data. From the second step of monitoring the light intensity and the monitoring result, the optimum off-pulse width corresponding to the multi-value data is determined. Using the third step, the read ε, and the optimum off-pulse width determined in the third step, the second test data is test-recorded by sequentially changing the recording power, and the reflection corresponding to the second test data. And a fourth step of monitoring the light intensity and determining the optimum recording power from the monitoring result.

  The invention according to claim 27 is an information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse and erase pulse. A recording parameter comprising a recording power Pw pre-recorded on the optical disc, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. The first test data is test-recorded by sequentially changing the top pulse width Ton using the read recording power, ε, and off-pulse width Toff, and the reflection corresponding to the first test data. The optimum top pulse width corresponding to the multi-value data is determined from the second step of monitoring the light intensity and the monitoring result. And a third step.

  A twenty-eighth aspect of the invention is the information recording method according to any one of the twenty-first to twenty-seventh aspects, wherein the determined optimum recording parameter is recorded in a storage device of the information recording apparatus.

The invention according to claim 29 is an information recording apparatus for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erase pulse. A recording parameter consisting of a recording power Pw pre-recorded on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data. First means for reading, second means for successively recording the first test data by changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data, and the monitoring result From the third means for determining the optimum recording power and the monitoring result at the optimum recording power, the relationship between the multi-value data m and the reflected light intensity I Seeking I = a · m + b, and a fourth means for calculating the square r ² of the correlation coefficient r, the determining the linearity of the multi-valued data m and the reflected light intensity I with the r ² Using the means 5 and the optimum recording power determined in the third step, the top pulse width Ton is sequentially changed to test record the first test data, and the reflected light intensity corresponding to the first test data is obtained. A sixth means for monitoring, a seventh means for determining the optimum top pulse width from the monitoring result, and an optimum off pulse corresponding to the multi-value data from the monitoring result at the optimum top pulse width determined by the seventh means. And an eighth means for determining each of the widths.

  According to a thirty-third aspect of the present invention, in the information recording apparatus according to the twenty-ninth aspect, the determined optimum recording parameter is recorded in a storage device.

  The invention according to claim 31 uses a recording pulse composed of a set of top pulse, off pulse, and erase pulse at a predetermined recording power so that the reproduction signal level changes in multiple stages according to the multi-value data. An optical disk on which recording marks are recorded on a recording layer in a cell unit, at least a ratio ε of recording power Pw, erasing power Pe and recording power Pw, top pulse width Ton and off-pulse corresponding to multi-value data A recording parameter consisting of the width Toff is recorded in advance.

  A program according to a thirty-second aspect comprises an instruction for causing a computer to execute the steps of the information recording method according to any one of the first to nineteenth and the twenty-first to twenty-eighth aspects.

  A computer-readable recording medium according to a thirty-third aspect records the program according to the thirty-second aspect.

  According to the first aspect of the present invention, the user data is recorded after the optimum recording pulse width and the optimum recording power are obtained by the test recording, so that it is affected by the individual difference of the optical disc and the information recording apparatus and the use environment. And stable recording can be performed.

  According to the second aspect of the present invention, the minimum top pulse width necessary for the reflected light intensity to reach the saturation value by the test recording is determined as the optimum top pulse width, so that thermal interference during recording is suppressed. And can be recorded so that the multi-value data can be accurately reproduced.

  According to the third aspect of the invention, in the approximate expression obtained from the result of the test recording, the top pulse width that minimizes the first-order coefficient is determined as the optimum top pulse width. And the multi-value data can be recorded so that it can be reproduced accurately.

  According to the invention described in claim 4, since the off-pulse width for each multi-value data is determined from the result of the test recording, stable recording is not affected by the individual difference of the optical disk and the information recording apparatus and the use environment. Can be performed.

  According to the fifth aspect of the present invention, since the off pulse width for each multi-value data is determined using the approximate expression obtained from the test recording result, the off pulse width can be set with higher accuracy.

  According to the sixth aspect of the present invention, the optimum top pulse width is calculated by calculating the relationship between the off-pulse width and the reflected light intensity at the top pulse width where the test recording is not performed, using the approximate expression obtained from the test recording result. Since it is determined, the number of test recordings can be reduced and the top pulse width can be set more accurately.

  According to the seventh aspect of the present invention, since the top pulse width is set so that the reflected light intensity is substantially linear with respect to the off-pulse width, the reflected light intensity adjustment margin when performing the recording correction is made equal. be able to.

  According to the invention described in claim 8, since the recording pulse is optimized by the test recording, the trial writing is performed again, and the recording power that minimizes the signal level deviation is determined as the optimum recording power. The multi-value data can be recorded so that it can be reproduced.

  According to the ninth aspect of the invention, the top pulse width Ton (m) and the off pulse width Toff (m) corresponding to the multi-value data m are both set to be an integral multiple of the unit time T. A pulse train can be generated by a simple circuit using a recording clock.

  According to the tenth aspect of the present invention, a wide margin can be secured in the off-pulse width for setting the level of reflected light intensity corresponding to multi-value data at a constant interval, and a recording pulse train in which an error in pulse width is suppressed is configured. can do.

  According to the eleventh aspect of the present invention, a wide margin can be secured in the combination of the top pulse width and the off pulse width that sets the level of the reflected light intensity corresponding to the multi-value data at a constant interval, and the off pulse width is linear. Thus, it is possible to select a recording pulse train in which the error of the pulse width is suppressed while maintaining the characteristics.

  According to the twelfth aspect of the invention, recording marks that are sufficiently long with respect to the cell period can be set to the same heating condition, and variations in mark length can be suppressed.

  According to the thirteenth aspect of the present invention, the setting items of the recording pulse train of multi-value data can be made the same for various phase change recording media, and the optimum recording pulse width can be set with the minimum necessary information. This makes it possible to shorten operations such as optimum pulse width calculation and optimum recording power calculation trial writing.

  According to the fourteenth aspect of the present invention, the recording mark corresponding to the multi-value data is formed by setting the necessary minimum recording clock frequency without using the recording clock period having an excessive resolution with respect to the cell clock period. It becomes possible.

  According to the fifteenth aspect of the invention, since the top pulse coefficient is set to be increased with respect to the recording mark whose reflected light intensity shows the minimum level, the linearity with the off pulse width is used while widely using the dynamic range of the reflected light intensity. It becomes possible to keep sex.

  According to the sixteenth or seventeenth aspect of the present invention, a sufficiently small mark can be formed with sufficient rapid cooling depending on the spot diameter, and the linearity between the mark length and the off-pulse width can be maintained.

  According to the invention of claim 18 or 19, since the target is a phase change type optical recording medium using a phase change recording material such as Ag-In-Sb-Te as a recording material, the mark shape can be controlled with high accuracy. .

  According to the invention of claim 20, since the user data is recorded after obtaining the optimum recording pulse width and the optimum recording power by the test recording, it is affected by the individual difference of the optical disc and the information recording apparatus and the use environment. And stable recording can be performed.

  According to the twenty-first aspect of the present invention, the user data is recorded after the optimum recording power is obtained by the test recording, so that stable recording can be performed without being affected by individual differences of the optical disk and the information recording apparatus and the use environment. Can be performed.

  According to the twenty-second aspect of the present invention, the relationship between the multi-value data and the reflected light intensity is approximated using a quadratic function, and the linearity between the multi-value data and the reflected light intensity is compared by comparing the quadratic coefficients. Therefore, it can be easily determined.

  According to the twenty-third aspect of the present invention, after the optimum recording power is determined by the first test recording, the optimum off-pulse width is obtained by the second test recording and then the user data is recorded. Can be set.

  According to the twenty-fourth aspect of the present invention, after the optimum recording power is determined by the first test recording, the optimum top pulse width and the optimum off-pulse width are obtained by the second test recording, and then the user data is recorded. The recording parameters can be set with higher accuracy.

  According to the invention described in claim 25, the user data is recorded after obtaining the optimum top pulse width and the optimum off-pulse width by the test recording, so that it is affected by the individual difference of the optical disc and the information recording apparatus and the use environment. And stable recording can be performed.

  According to the twenty-sixth aspect of the present invention, after the optimum off-pulse width corresponding to the multi-value data is determined by the test recording, the user data is recorded after the optimum recording power is obtained by the second test recording. Thus, stable recording can be performed without being affected by individual differences of information recording apparatuses and usage environments.

  According to the twenty-seventh aspect of the present invention, since the user data is recorded after the optimum top pulse width is obtained by test recording, it is not affected by the individual difference of the optical disk and the information recording apparatus and the use environment in a short time. Stable recording can be performed.

  According to the invention described in claim 28, the recording parameter determined by the test recording is stored in the storage device of the information recording device, and when the next recording is performed, the recording parameter is set based on this information. It can be optimized in a short time.

  According to the invention of claim 29, after the optimum recording power is determined by the first test recording, the optimum top pulse width and the optimum off-pulse width are obtained by the second test recording, and then the user data is recorded. The recording parameters can be set with higher accuracy.

  According to the invention of claim 30, since the recording parameter determined by the test recording is stored in the storage device of the information recording device, and the next recording is performed, the recording parameter is set based on this information. Can be optimized in a short time.

  According to the invention of claim 31, at least the recording power Pw, the ratio ε between the erasing power Pe and the recording power Pw, the top pulse width Ton and the off pulse width Toff corresponding to the multi-value data are recorded in advance on the optical disc. Therefore, the initial values of the recording parameters can be set by reproducing them.

The best mode for carrying out the present invention will be described with reference to the drawings.
[First embodiment]
First, recording / reproducing of multi-value data in the information recording method of the present invention will be described. In order to form multi-value data, it is mainly necessary to optimize the recording pulse. In general, this method performs test recording, and determines a recording pulse condition that minimizes the deviation of the reproduction signal by suppressing thermal interference during recording from the monitoring result.

  Here, the recording pulse for one cell is composed of a set of top pulse, off pulse and erase pulse as shown in FIG. 1, and the reflected light intensity is the top pulse width Ton, off pulse width Ton, and recording power Pw. And erasing power Pe.

  A procedure for obtaining recording characteristics necessary for selecting the optimum recording pulse width as recording conditions will be described with reference to a schematic flowchart shown in FIG. This procedure is executed by a microcomputer provided in the target information recording apparatus (optical disk apparatus). In this case, a program for causing the computer to execute the procedure is created and recorded on a predetermined recording medium such as a CD-ROM, or the program is loaded and installed on the computer via a communication network such as the Internet. It is also possible to adopt a configuration for causing a computer to execute.

  First, after setting the off pulse width Ton to the initial value Ton (i) (step S1), a test recording process is performed (steps S2 to S8).

  In this test recording process, first, the first test data is recorded and reproduced with the top pulse width Ton = Ton (1) (steps S2, S3 and S4), and the reproduction signal is sampled (step S5). As the first test data, for example, as shown in FIG. 3, the multi-value data m is associated with an off pulse width Toff (1, m) (where “1” means Ton (1)). It is desirable to keep it. By doing so, a change in the reflected light intensity I with respect to the off-pulse width Toff can be easily measured.

  The result is shown in FIG. FIG. 4 shows the values obtained by standardizing the reflected light intensity obtained as shown in FIG. 3 with I0 when the off-pulse width is sequentially changed with the Ton (1) fixed (step S3). In addition, I0 shows the reflected light intensity at the time of unrecording. In this example, Toff (1, m), that is, the on-pulse width is fixed at Ton (1), and the off-pulse width is sequentially changed corresponding to multivalues 0 to 7 (m = 0, 1, 2,..., 7). The reflected light intensity at the time of recording is set to I (1, m). Then, I (1, m) obtained in this way is stored in the storage device (step S6).

  In step S7, i defining the top pulse width is incremented. Then, the trial writing and the measurement of the reflected light intensity (steps S2 to S6) are performed in a single operation with the top pulse width set to Ton (2).

  This is repeated a predetermined number of times (in this case, i = 1 to k total k times) (steps S2 to S8). As a result, k pieces of graphs corresponding to FIG. 4 are obtained as a result of sequentially increasing the top pulse width from i = 1 to k (in this example, i = 1 to 8 for a total of 8 pieces). From the k graphs, for example, the result shown in FIG. 5 is obtained. FIG. 5 shows the result of changing the top pulse width in five stages, namely Ton0T, Ton0.8T, Ton1.6T, Ton2.4T, and Ton3.6T. In each curve shown in FIG. 5, the top pulse width Ton is fixed to 0T, 0.8T, 1.6T, 2.4T, and 3.6T, and the off pulse width is multi-valued for each top pulse width. A change in reflected light intensity obtained from the recording result when recording is performed while sequentially changing in correspondence with m = 0 to 7 is shown.

  As the recording power at this time, the optimum recording power stored in the optical disc or the optical disc apparatus is used as a temporary condition. In the processes in steps S2 to S8, the first test data is test-recorded by sequentially changing the top pulse width Ton, and the reflected light intensity corresponding to the first test data is monitored. It is executed as a means.

  Next, the optimum top pulse width Ton is determined (steps S9 to S11). The first method for determining the optimum top pulse width is to detect the level Is at which the reflected light intensity saturates from FIG. 5 obtained by steps S2 to S8 (step S9), and then I (i, j). Finds Toff (i, j) reaching Is obtained here (step S10).

  In the example of FIG. 5, Is is reached at three points Toff (1.6T, 12T), Toff (2.4T, 10T), and Toff (3.2T, 6T). That is, the off pulse width when the reflected light intensity value reaches the saturation value Is on the curve of the top pulse width Ton1.6T is 12T (Toff (1.6T, 12T)), and the top pulse width is also Ton2. The off-pulse width when the reflected light intensity value reaches the saturation value Is on the 4T curve is 10T (Toff (2.4T, 10T)), and the reflected light intensity on the curve with the top pulse width of Ton3.6T. The off-pulse width when the value reaches the saturation value Is is 6T (Toff (3.6T, 6T)).

  Of these three conditions, the pulse condition with a long off-pulse width reaching the saturation level Is, that is, the shortest top pulse width is set as the optimum recording top pulse width Ton (step S11). In this example, Toff (1.6T, 12T) is applicable, and the optimum top pulse width is selected as 1.6T. The processes in steps S9 to S11 are executed as a second step or a second means for determining the optimum top pulse width Ton from the monitor result. This is to suppress the thermal interference described in the problem.

As a second method for determining such an optimum top pulse width, a Toff-reflected light intensity curve as shown in FIG. 5 is approximated by a cubic function, and the absolute value of the first order coefficient of the approximate expression is obtained. The characteristic is obtained by setting the minimum top pulse width condition, that is, the condition where the slope of the curve is small as the optimum top pulse width. In the example of FIG. 5, the approximate expression is
I = a · Toff ³ + b · Toff ² + c · Toff + d
When I = y, Toff = x, and Ton = 1.6T, y = 0.00003x ³ + 0.0021x ² −0.0775x + 0.9897
Thus, the first-order coefficient is obtained as 0.0775. Next, when Ton = 2.4T, y = 0.004x ³ −0.0017x ² −0.085x + 1.02
Thus, the first-order coefficient is obtained as 0.085. Next, when Ton = 3.6T, y = −0.0005x ³ + 0.0174x ² −0.1845x + 1.0143
Thus, the primary coefficient is obtained as 0.1845. As a result, since Ton = 1.6T has the smallest absolute value of the first-order coefficient, Ton = 1.6T is obtained as a representative value of the optimum recording pulse width.

  The approximation of the curve is performed by a known method such as a least square method. The same applies to the approximation of other curves in each embodiment of the present invention.

Next, the reflected light intensity corresponding to the multi-value data is assigned (step S12). Specifically, the reflected light intensity corresponding to the multi-value data is determined in the range of I0 and Is where the reflected light intensity is maximum and minimum. In the case of M-value recording (M: an integer of 2 or more), the reflected light intensity L (m) that is the target value of the multi-value data m (the reflected light intensity corresponding to the multi-value data 0 and 7 is I0 and Is, respectively). Is)
L (m) = I0− (I0−Is) / (M−1)
Calculate using the following formula. L (1) to L (6) in FIG. 5 are the reflected light intensities corresponding to the multivalued data obtained in this way.

  Subsequently, an off pulse width Toff corresponding to the reflected light intensity I obtained in this way is determined (steps S13 to S14). Here, using the monitoring result of the trial writing with the optimum top pulse width Ton determined in the second step (steps S9 to S11), the off pulse width Toff that becomes the reflected light intensity calculated in the third step (step S12) is set. Select.

  As a method for determining the off-pulse width Toff, the following method can be cited.

(a) Linear interpolation method:
The off-pulse width at the time of test recording of each of the multi-value data m is Toff (m), the reflected light intensity obtained at this time is I (m), and the coefficient is α. At this time, the optimum off pulse width Toff opt (m) corresponding to the multilevel data m is expressed by the following relational expression regarding the reflected light intensity L (m) corresponding to each of the multilevel data m:
Toff opt (m) = α · (I (m) −L (m)) / (I (m + 1)
−I (m)) / (Toff (m + 1) −Toff (m)) + Toff (m)
Ask for.

(b) Method for setting Toff (m) using an approximate expression:
Approximate expression obtained in the second step (steps S9 to S11) described above:
I (m) = a · Toff (m) ³ + b · Toff (m) ² + c · Toff (m) + d
Is used to find Toff (m) from which the reflected light intensity L (m) corresponding to the multi-value data m is obtained. In this method, the pulse width can be set with higher accuracy than the method (a).

  The processes in steps S13 to S14 are executed as a third step or a third means for determining the optimum off pulse width Toff corresponding to the multi-value data.

  Finally, the optimum recording power determination process is performed (steps S15 to S23). That is, using the recording pulse conditions determined in the above procedure (step S14), the recording power Pw (s) is sequentially changed to record / reproduce known multilevel random data (steps S15, S16, S17). Then, the deviation of the reflected light intensity of each sampled multivalued data is calculated for each value of the multivalued data m (steps S18 and S19). Then, the recording power Pw (s) that minimizes the deviation of the reflected light intensity for each value of the multi-value data m is determined again as the optimum recording power (step S22).

  Therefore, according to the present embodiment, since the optimum recording pulse width (top pulse, off pulse) and optimum recording power are obtained by test recording, the user data is recorded, so that the optical disk and the information recording apparatus Stable recording can be performed without being affected by individual differences and use environment.

[Second Embodiment]
In the second embodiment of the present invention, the top pulse width is set according to the multi-value data so that the off-pulse width becomes linear with respect to the multi-value data. Thereby, an adjustment margin of the off pulse width is secured.

  For example, when the wavelength is 405 nm, NA is 0.65, and the cell length is 0.28 μm, as shown in FIG. 9 and FIG. Increase the width (increase the top pulse coefficient).

  This will be described in detail below. The optical disk of the present embodiment is a phase change optical disk capable of recording with a laser beam having a wavelength of 405 nm. The substrate is made of polycarbonate having a diameter of 120 mm and a thickness of 0.6 mm, and a groove is formed on the substrate surface by injection molding. The track pitch is 0.46 μm and is formed as a continuous spiral from the inner periphery to the outer periphery. On this substrate, a dielectric film, a phase change recording film, a dielectric film, and a reflective film were sequentially laminated to produce a phase change optical disk.

  The information recording apparatus of this embodiment will be described with reference to FIG. FIG. 6 is a block diagram showing a schematic configuration example of an optical disc apparatus which is an information recording apparatus according to the present embodiment (the same applies to other embodiments).

  To record information, first, information is output from the modulation signal generator 1 and input to the recording waveform generation circuit 2. The recording waveform generation circuit 2 outputs a recording pulse corresponding to the modulation signal. By inputting this to the laser driving circuit 3, laser light is emitted from the semiconductor laser provided in the pickup head 4 by driving by the laser driving circuit 3. The laser beam is condensed on the optical disk 6 by the objective lens 5 to form a recording mark.

  At the time of reproduction, the reflected light from the optical disk 6 is taken into a light receiver provided in the pickup head 4 and converted into an electric signal. This electrical signal passes through the reproduction signal amplifier 7 and is input to the A / D converter 8. The arithmetic circuit 9 calculates a recording pulse and recording power based on the light reception signal converted into a digital signal by the A / D converter 8, and inputs the calculation result to the laser driving circuit 3. A portion denoted by reference numeral 10 is a spindle motor that rotationally drives the optical disk 6.

  For recording / reproducing data, an optical disk device having a wavelength of 405 nm and an objective lens 5 of NA 0.65 was used. The recording / reproducing linear velocity is 3.6 m / s, the recording clock cycle T = 4.86 ns, the circumferential length of one cell is 0.28 μm (= 16 T), the recording power Pw = 7.8 mW, and the erasing power Pe. = 4.9 mW and bias power Pb = 0.1 mW.

  As a method for setting recording conditions, first, the following recording / reproducing characteristics were confirmed. That is, from the result of the test recording as shown in FIG. 5, the off-pulse width Toff (m) at which the reflected light intensity L (m) for each multi-value data m is obtained at each top pulse width Ton. Then, known multi-value random data was recorded on the optical disc 6 under these setting conditions.

  FIG. 7 shows the dependence of σ / DR on the top pulse width. σ / DR is a value obtained by normalizing the deviation of the reflected light intensity with the maximum amplitude, σ is a value obtained by averaging the deviation of the reflected light intensity for each multi-value data calculated from the reproduction result, and DR is the maximum reflected light intensity I0− Saturated reflected light intensity Is. From the characteristics of FIG. 7, it can be seen that the deviation of the signal level is minimized when Ton = 1.6T. By selecting the smallest Ton among the top pulse widths Ton at which the reflected light intensity reaches the saturation level Is as the optimum top pulse width, it can be confirmed that thermal interference is suppressed and good signal quality is obtained.

  In the first embodiment described above, the top pulse width Ton is constant, and the reflected light intensity from the recording mark is modulated by changing the off pulse width Toff. In the second embodiment, in order to obtain a more optimal setting, the change in reflected light intensity corresponding to m-valued data is linear with respect to the off-pulse width Toff (for example, as shown in FIGS. 9 and 10). Thus, the top pulse width Ton (top pulse coefficient) is individually set for each value of the multi-value data m (see FIGS. 9 and 10).

  The present embodiment assumes the case where multi-level recording is performed on an optical disc for which a sufficient reproduction margin cannot be secured. That is, for optical discs that require recording correction as in the prior art, the initial recording pulse condition is set to a recording pulse condition in which the off-pulse width interval between each value of multi-value data is substantially equal. A light intensity adjustment margin can be secured.

  The pulse condition setting method in the present embodiment is as follows.

  First, test recording as described in steps S2 to S8 in FIG. 2 is performed in the same manner as in the first embodiment, and a monitoring result as shown in FIG. 5 is obtained.

  Next, the off pulse width Toff of the multi-value data “7” (m = 7) is determined. Here, in the optimum top pulse width Ton determined in the second step (steps S9 to S11) of the first embodiment, the off pulse width at which the reflected light intensity I reaches the saturation value is set as Toff of the multi-value data 7. In the example of FIG. 5, since the optimum top pulse Ton = 1.6T as described above, Toff = 12T is obtained as the off-pulse width in which the reflected light intensity reaches the saturation value Is.

  Then, as in the first embodiment, a curve obtained at each top pulse width Ton is approximated (for example, by a cubic function). Next, using this result, the coefficient of each approximate expression is approximated as a function of the top pulse width Ton. Then, by using the approximate expression of each coefficient obtained in this way, a Toff-reflected light intensity curve for the top pulse width Ton that is not actually subjected to test recording is approximately obtained by calculation.

  Using this calculation result, an off pulse width for each multi-value data is set. That is, a straight line (shown by a broken line in FIG. 5) connecting the reflected light intensity I0 in the unrecorded state and the saturation value Is (Toff = 12T) of the reflected light intensity, and the third step (step of the first embodiment) The intersection (Toff (m), I (m)) with the level of the reflected light intensity L (m) corresponding to each m of the multi-value data set in 12) is the off-pulse width Toff ( m) (see FIG. 5).

Next, the top pulse width Ton is determined. That is, when Toff (m) obtained as described above, the top pulse width for obtaining L (m) is expressed by the approximate expression I (m) described in the third step (step 12) of the first embodiment. ) = A · Toff (m) ³ + b · Toff (m) ² + c · Toff (m) + d
Use to calculate. This is performed for the multi-value data 1 to 6 (m = 1 to 6).

  FIG. 8 shows the recording pulse conditions set by this method. In FIG. 8, the horizontal axis represents the multi-value data m, and the vertical axis represents the pulse width T. As can be seen from FIG. 8, by adjusting the top pulse width Ton, the off-pulse width Toff can be set at regular intervals (linear with respect to multi-value data) for multi-value data.

  According to the recording pulse conditions of the first embodiment and the second embodiment described above, recording correction is performed, and σ / DR when multi-value random data is recorded is compared before and after the recording correction. Table 1 shows. The configuration of the optical disc and the optical disc apparatus in this case is as described above. As can be seen from the table, the deviation is smaller in the recording pulse condition 1 (condition of the first embodiment) before the recording correction, but in the condition 2 (condition of the second embodiment) when compared after the recording correction. Can reduce the deviation. Therefore, when recording on an optical disk that needs to be corrected to widen the reproduction margin, the change in reflected light intensity corresponding to the multi-value data is linear as the initial recording pulse condition as in the second embodiment. It can be seen that it is preferable to adopt a pulse condition such that

  By the way, when the above-described recording / reproducing characteristics are applied to the optical disc apparatus, the configuration of the recording pulse is set as follows.

  That is, since the recording mark corresponding to each value of the multi-value data has a smaller size than the shortest mark of the conventional binary recording, the width of the recording pulse and the width of the cooling pulse can be detected by detecting the reflected light intensity of the mark portion. It is necessary to set it with high accuracy while checking the level. In particular, when the mark level is 0 (maximum detected light amount) or the mark level is 7 (minimum), the linearity is greatly lost, and an extremely narrow pulse width setting or an extremely wide pulse width setting may occur.

  Therefore, in the present embodiment, when a phase change optical recording medium using an Sb—Te recording material is targeted, the following settings are made for the above-described recording pulse setting conditions.

  Since the pulse width with the minimum resolution is set by a simple circuit, a recording clock of 16 to 64 times can be generated by using a PLL or a ring oscillator with the cell clock as a basic clock. By forming a recording pulse in synchronization with this recording clock cycle, it becomes easy to generate a recording waveform corresponding to each multi-value data.

  Here, in the configuration of FIG. 1, the recording clock cycle is 1/16 of the invention cell cycle Tc. However, if the top pulse width Ton and the off-pulse width Toff calculated in the basic configuration are set by the 16-fold clock cycle T, the pulse width It is difficult to make the reflected light intensity level linear according to the multi-value data due to insufficient setting resolution. Therefore, in order to set the pulse width obtained from the approximate expression as described above, it is necessary to generate a 128-fold or 256-fold clock of the cell clock and set the minimum pulse width with high resolution.

  Therefore, in the present embodiment, the top pulse width Ton (m) and the off pulse width Toff (m) corresponding to the multi-value data m are basically set so as to be an integral multiple of the unit time T. The recording pulse structure is obtained by using a 32-cycle clock or a 64-times clock synchronization circuit of the cell cycle Tc, and is minimized by a multiplication time, that is, a unit time Tc / n obtained by dividing the cell cycle Tc into n equal parts (n is a fixed value). The pulse resolution is obtained.

More specifically, if the top pulse width Ton is a top pulse coefficient j (j is an integer value) and the off pulse width Toff is an off pulse coefficient k (k is an integer value), the setting of each pulse width Ton and Toff is The following formula Ton = j × Tc / n
Toff = k × Tc / n
(N = 32 or 64)
This is done by setting the coefficients j and k in FIG.

  Here, from the relationship between the pulse width obtained by the test recording and the procedure for determining the optimum pulse width and the reflected light intensity, the top pulse coefficient j and the off-pulse described above can obtain the reflected light intensity that matches the multi-value data. Select a combination of coefficients k. At this time, in order to minimize the influence of thermal interference between adjacent marks, a combination is selected in which the changes in these coefficients j and k are as linear as possible.

  First, Table 2 below shows the set values for obtaining the reflected light intensity of each value of the multivalued data of the top pulse width Ton and the off pulse width Toff with the minimum resolution of 32 times clock cycle T ′ = Tc / 32. .

  Next, Table 3 below shows setting values for obtaining the multilevel levels of the top pulse width Ton and the off pulse width Toff with the minimum resolution of 64 times the clock cycle T ″ = Tc / 64.

  As shown in FIG. 9 and FIG. 10, in order to increase the off-pulse coefficient (Toff coefficient) k in a substantially linear manner to obtain the accuracy of multi-value data, the reflected light intensity of the multi-value data is changed from the maximum level to a substantially intermediate level. It can be seen that this can be realized by increasing the invention top pulse coefficient (Ton coefficient) j with respect to the recording mark to be shown (that is, the part where the number of the multi-value data is small; the left part in the figure).

  Further, the top pulse coefficient (Ton coefficient) j is made the same for the recording mark whose reflected light intensity is lower than the intermediate level (that is, the part where the number of the multi-value data is large; the right part in the figure). Further, the top pulse coefficient (Ton coefficient) j is increased in order to maintain the off-pulse coefficient (Toff coefficient) k substantially linear with respect to the minimum reflected light intensity (multi-value data 7). However, for the multi-value data 7, the linearity of the off-pulse coefficient (Toff coefficient) k is lost, but the top pulse coefficient (Ton coefficient) j can be the same, and either setting can be used.

  By setting the top pulse width Ton and off-pulse width Toff in this way, it is possible to handle multi-value data by setting the necessary minimum recording clock frequency without using an excessively multiplied clock for the cell clock period. It is possible to form recorded marks. Therefore, even at a higher recording speed, it is possible to easily obtain the minimum resolution for setting the pulse width.

[Third embodiment]
The recording mark length at which the linearity with the off-pulse width disappears depends on the recording spot diameter, and the experimental results show that it is about ¼ of the spot diameter. Therefore, in the third embodiment of the present invention, when recording multi-value data in which the recording mark length is 1/4 or less of the spot diameter, the top pulse coefficient is increased, and the multi-value data and the off-pulse width are increased. The linearity is maintained. Here, the recording mark length corresponding to the multi-value data depends on the recording linear density, that is, the cell length. Therefore, the multi-value data for increasing the top pulse width coefficient changes according to the combination of the recording spot diameter and the cell length. This will be described in detail below.

In the second embodiment described above, the area of the recording mark where the top pulse coefficient j is increased differs depending on the recording spot diameter and the linear density of the recording mark, and has a correlation with the spot diameter. In the case of an optical pickup having a general RIM intensity (about 50%), assuming that the wavelength λ, the numerical aperture NA, and the off-pulse coefficient k, the spot diameter φ that becomes the relative intensity 1 / e ² with respect to the maximum value of the intensity distribution is φ = k × λ / NA (k≈0.86), and in the optical pickup of the first embodiment, the spot diameter φ≈0.53 μm.

  The cell length of the recording mark period is 0.28 μm, and seven types of recording mark lengths are formed according to the multi-value data m. At this time, in the phase change type optical recording medium using Ag—In—Sb—Te or the like as a recording layer, when a mark that is sufficiently smaller than the spot diameter is formed, if the off-pulse width as a cooling pulse is shortened, sufficient rapid cooling is performed. Since it cannot be obtained and the formation of the mark becomes insufficient, the linearity between the mark length and the off pulse width is lost. Accordingly, the mark in the region where the off-pulse width Toff is nonlinear has a narrow cooling time setting interval, and an accurate mark length cannot be obtained, so that the aforementioned σ / DR value is deteriorated. As shown in FIG. 11, the condition for eliminating the linearity of the off-pulse width Toff is that the recording mark length is about ¼ of the spot diameter φ, and the CN ratio when a single mark and a space are continuously recorded. It is also in good agreement with the linear density region where drastically decreases.

  Under the conditions of the first embodiment, 1/4 × φ≈0.13 μm, and the mark length corresponding to the multi-value data 3 is 0.12 μm. Therefore, in order to record the recording marks corresponding to the multi-value data 0, 1, 2 while maintaining the linearity of the off-pulse width Toff, it is necessary to increase the top pulse width Ton and increase the temperature reached by heating. It is valid. As a result, rapid cooling is performed and the amorphous region is expanded, so that the reflected light intensity can be adjusted to the target level.

  Further, in an optical pickup using a red LD such as a DVD, λ = 660 μm, NA = 0.65 is applied, and the spot diameter φ≈0.87 μm. In this case, by increasing the top pulse width Ton corresponding to multi-value data with a recording mark length of 0.22 μm or less, the linearity of the off-pulse width Toff can be easily maintained, and the σ / DR value is good. Recording can be done.

  As described above, the formation of the minute mark by selecting the top pulse width Ton and the off pulse width Toff is performed by using a Ge—Sb—Te system, a Ge—Te—Sb—S system, a Te—Ge—Sn—Au system as the recording layer, Ge-Te-Sn, Sb-Se, Sb-Se-Te, Sn-Se-Te, Ga-Se-Te, Ga-Se-Te-Ge, In-Se, In-Se It is particularly effective in an optical recording medium using the -Te system, Ag-In-Sb-Te system, or the like in which the amorphous phase and the crystalline phase change due to rapid cooling and slow cooling, and the mark length can be easily controlled.

[Fourth embodiment]
In the present embodiment, first, the optimum recording power is obtained by test recording. Then, in order to set the signal level with high accuracy when it is determined that the linearity of the reproduced signal level is low at the obtained optimum recording power, the optimum off pulse width or the optimum top pulse width and off pulse width are derived again by test recording. (The optimum recording power is used as the recording power of the test recording at this time).

  On the other hand, when it is determined that sufficient signal level linearity is obtained with the obtained recording power, the test recording is ended here. When sufficient reproduction reliability is obtained only by adjusting the recording power, it is not necessary to perform the subsequent steps, and therefore the time required for optimizing the recording conditions can be shortened.

  The procedure for optimizing recording conditions according to the present embodiment is shown in the flowchart of FIG. This procedure is also executed by the microcomputer provided in the target information recording apparatus (optical disk apparatus). In this case, a program for causing the computer to execute the procedure is created and recorded on a predetermined recording medium such as a CD-ROM, or the program is loaded and installed on the computer via a communication network such as the Internet. It is also possible to adopt a configuration for causing a computer to execute.

  First, in step S31, a recording parameter is read from the optical disc. Here, recording parameters such as a recording power Pw, an erasing power Pe, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data are pre-formatted information on the optical disc. , Recorded as wobble information or pre-pits or recording marks. The recording device reproduces the information and uses it as an initial value of the recording condition.

  Next, test recording to derivation of an approximate expression are performed in steps S32 to S39. The initial value of the recording power is set (step S32), the first test data as shown in FIG. 3 is recorded and reproduced (steps S34 and S35), and the multi-value data m is reflected at the recording power Pw (s). The light intensity Pw (s, m) is sampled (step S36) (refer to FIG. 15 for the test data reproduction signal). Here, in the case of 8-level recording, m = 0, 1, 2,.

Next, the relationship between the multi-value data m obtained from the sampling result and the reflected light intensity Pw (s, m) is approximated by a quadratic function Pw (s, m) = As · m ² + Bs · m + Cs, The coefficients As, Bs, and Cs of the approximate expression obtained here are stored in the storage device (step S37). These steps (steps S34 to S37) are repeated t times by changing the recording power sequentially (steps S38 and S39).

  In step S40, the optimum recording power is determined. Here, referring to the coefficient of the approximate expression for each recording power obtained in the above process, the secondary coefficient | As | selects the minimum value (| As |: absolute value of As), and the corresponding recording power Is obtained as the optimum recording power.

  FIG. 16 shows an example of the relationship between the multi-value data m and the reflected light intensity I obtained when the recording power is changed, obtained in the above process (repetition of steps S34 to S37). When a quadratic approximate expression is obtained for each curve, the approximate expression is closer to a straight line as the absolute value of the quadratic coefficient is smaller. Therefore, the recording power that minimizes the absolute value of the secondary coefficient is determined as the optimum recording power candidate.

In the case of FIG. 16, the approximate expression is
I = F · m ² + G · m + H
If I = y and m = x, the following approximate expression is given for each recording power:
Pw = 6.5 mW: y = −0.0102x ² + 0.0016x + 0.7963
Pw = 7.5 mW: y = −0.0012x ² −0.0945x + 0.7992
Pw = 8.5 mW: y = 0.0132x ² −0.197x + 0.7533
In this example, the absolute value “0.0012” of the quadratic coefficient of the approximate expression corresponding to Pw = 7.5 mW is the smallest, and this is the optimum recording power candidate.

In step S41, the linearity between the multi-value data and the reflected light intensity is determined. Here, at the optimum recording power determined in step S40, the relationship between the multi-value data m and the reflected light intensity Pw (s, m) is approximated by a linear function Pw (s, m) = Dm + E, and its correlation coefficient r. Is calculated as a square r ² . If r ^{2 at} this time is smaller than the desired value, the process proceeds to step S42, and if not, the test recording is terminated.
A method for determining the linearity between the multi-value data and the reflected light intensity in this case will be described with reference to FIG. FIG. 17 shows the result of approximating the relationship between the multi-value data and the reflected light intensity using the linear expression in the case of the recording power (Pw = 7.5 mW) determined from the three types of recording power shown in FIG. It is. Here, a value obtained by squaring the correlation coefficient r was calculated, and the value of this coefficient was used as a criterion for determining whether or not the coefficient was linear. The correlation coefficient was calculated using the Pearson product moment correlation coefficient defined by the following equation.

Here, x _{ave is} the average value of x, and y _ave is the average value of y.

That is, the large value r ² means that the error between the monitoring result and the approximate expression obtained here is small. Therefore, it can be determined from this value whether the relationship is linear. If r ² is smaller than the predetermined value, it is necessary to improve the linearity, and the process proceeds to step S42 for adjusting the pulse width.

  Here, the procedure for deriving the optimum pulse width in steps S43 to S56 is the same as steps S1 to S14 in FIG. 2 described in the first embodiment. Here, in the first embodiment, when the pulse width is derived, the relationship between the pulse width and the signal level is approximated by a cubic function, but in the present embodiment, an example is obtained by approximation by a quadratic function. Will be described.

  First, the Toff-reflection intensity curve is approximated by a quadratic function at each top pulse width Ton on which test recording has been performed. Next, it is determined whether or not this curve reaches Is, and the top pulse width Ton from which the curve reaching Is is obtained is selected. Then, among the selected top pulse widths Ton, the top pulse width Ton that minimizes the absolute value of the first-order coefficient in the corresponding approximate expression is determined as the optimum top pulse width.

In the example of FIG. 5, the approximate expression is
I = J · Toff ² + K · Toff + L
And if I = y and Toff = x,
Ton = 1.6T: y = 0.527x ² −0.0806x + 0.9921
Ton = 2.4T: y = 0.0001x ² −0.1155x + 1.0383
Ton = 3.2T: y = 0.008x ² −0.429x + 0.9893
Thus, Ton = 1.6T is selected as a representative value of the optimum recording pulse width.

  Further, the off-pulse width for each multi-value data may be set using the quadratic approximate expression used here. The setting method is the same as the method described in the second embodiment.

  Even when the relationship between the pulse width and the signal level is approximated by a linear function, the optimum top pulse width can be determined by the same procedure. Furthermore, the off-pulse width for each multi-value data can be set using a first order approximation. However, although it depends on the characteristics of the optical disk to be used, it is preferable to use a high-order approximation to accurately set the off-pulse width.

  If the determined recording parameters are stored in the recording device after the test recording is completed, the test recording can be performed based on this information when recording next time, and the time required for optimizing the recording conditions is shortened. be able to. The information to be recorded is at least information relating to the optical disc manufacturer and recording parameters determined by the test conditions (see Table 4 below). Not only the optical disc manufacturer but also information on the type of optical disc (recording layer material: phase change material or dye material) may be stored in the storage device. This is because even if it is not the optical disc that has been test-recorded, if the disc manufacturer and the disc type are the same, the recording parameters are considered to be almost the same, so the result of the test recording once obtained can be almost reflected. Test recording can be completed in a short time.

[Fifth embodiment]
In the present embodiment, the recording power is adjusted by changing the recording pulse width using the value read from the information written in advance as preformat information on the optical disk. The error between the set value of the recording power and the output value in the recording apparatus is adjusted by the top pulse width (laser beam irradiation time), and the linearity between the multi-value data and the signal level is adjusted by the off-pulse width. In this configuration, the optimum recording pulse width derivation flowchart starts from step S42 in FIG. 14, and therefore the recording condition setting time can be shortened.

[Sixth embodiment]
In this embodiment, the top pulse width is a value read from pre-written information as preformat information on the optical disk, and the optimum recording power is obtained after deriving the optimum off-pulse width by test recording.

  The recording condition derivation flowchart is the same as that in FIG. 2, except that k = 1 is fixed in step S2 of this step, and the top pulse width Ton uses a value read from the recording medium. With this configuration, the setting time of the top pulse width can be shortened. Here, since the recording power is optimized by test recording, the step of optimizing the top pulse width is omitted.

  In this embodiment, the value read from the optical disc is used as the recording power when setting the pulse width. Here, since the recording power has an error between the set value and the output value for each recording apparatus, there is a concern that sufficient recording characteristics cannot be obtained when the off-pulse width is set with a large error. Therefore, the inventors of the present invention investigated the influence on the recording quality when the pulse width was set in a state where the recording power setting error was large.

  The experimental results are shown in FIG. The recording data was a random pattern of multi-value data, and the recording quality was evaluated by σ / DR. The allowable value of σ / DR is 3% or less (σ / DR <3% corresponds to the jitter of DVD <15%). FIG. 18 shows that the best recording quality is obtained when the pulse width is set at a recording power of 7.5 mW, and at this time, σ / DR = 2.1%.

  When the pulse width is set at Pw = 6.5 mW, σ / DR = 2.5% at Pw = 6.5 mW. However, even in this case, if the recording is performed with Pw = 7.5 mW while maintaining the condition of the off pulse width, the recording quality decreases to σ / DR = 2.3%, which is largely different from the recording quality when the off pulse width is set with Pw = 7.5 mW. I understand that there is no.

  The same applies to the case where the recording power is shifted to the higher side (when the off pulse width is set at Pw = 8.5 mW). It was confirmed that sufficient recording quality can be ensured by determining the above.

[Seventh embodiment]
In the present embodiment, values read from the optical disc are applied to the recording power and the off pulse width corresponding to the multi-value data. Then, test recording is performed under the conditions, and the top pulse width is adjusted for each multi-value data, thereby adjusting the error between the set value of the recording power and the output value and the linearity between the multi-value data and the signal level.

  FIG. 19 shows a flowchart for determining the top pulse width for each multi-value data. This procedure is also executed by the microcomputer provided in the target information recording apparatus (optical disk apparatus). In this case, a program for causing the computer to execute the procedure is created and recorded on a predetermined recording medium such as a CD-ROM, or the program is loaded and installed on the computer via a communication network such as the Internet. It is also possible to adopt a configuration for causing a computer to execute.

  FIG. 20 shows the result of test recording performed in accordance with steps S61 to S72 of this flowchart. FIG. 20 shows test recording while changing the top pulse width in step S63 using the off-pulse width (see Table 5 below) for each multi-value data read from the optical disc in step S61 (step S64). The reproduction signal sampling (step S66) result I (m, s) obtained in step S65 is plotted. This I (m, s) indicates the reproduction signal level when the value m of the multi-value data is recorded in Ton (s).

  From the result of FIG. 20, Is at which the signal level is saturated is determined (step S69). The minimum Ton (s) at which I (7, s) reaches Is is determined (see Table 6, Ton = 1.6T in the example of FIG. 20) (step S70).

Next, the target signal level L (m) (signal level at which the multilevel data and the signal level are linear) for each of the multilevel data 1 to 6 is expressed by the following formula L (m) = I0−m · (I0 -Is) / 7
Get calculated using. Then, Ton (m, s) that satisfies the target value L (m) = I (m, s) for each multi-value data is obtained on the corresponding curve from the result of FIG. 20 (see FIG. 20). By this procedure, linearity can be ensured only by adjusting the top pulse width.

  Although the method for optimizing the recording parameters has been described, which flowchart is used may be selected according to the state of the information recording apparatus. In other words, if the laser power of the information recording apparatus is calibrated, the value read from the optical disk can be used as the recording power, so it is not necessary to optimize the recording power, and the recording pulse is optimized. Just good. If this is not the case, the laser power of the recording apparatus is not reliable (there is an error between the set power and the output power), so it is necessary to perform the optimization from the recording power.

  The above-described recording parameter optimization method according to each embodiment of the present invention creates a program for causing a computer to execute each procedure constituting the method, and stores the program on a predetermined recording medium such as a CD-ROM. It is possible to implement the program by recording the program on the computer or by loading and installing the program on a computer via a communication network such as the Internet. Alternatively, a circuit may be configured to execute the method using a hardware circuit, and the method may be implemented in the form of the hardware circuit.

  The present invention is not limited to the above-described embodiment, and can be realized in various other embodiments within the technical scope described in the claims described below.

It is a wave form diagram which shows the example of the recording pulse of the multi-value recording used by embodiment of this invention. It is a schematic flowchart which shows the example of a recording condition setting process of 1st embodiment of this invention. FIG. 6 is a characteristic diagram showing a result of examining a change in reflected light intensity with respect to an off-pulse width by associating multi-value data with an off-pulse width. It is a characteristic view which shows the result of having investigated the change of the reflected light intensity with respect to an off pulse width. It is a characteristic view which shows the result of having repeated test recording and the measurement of reflected light intensity in multiple times. It is a block diagram which shows the schematic structural example of the optical disk apparatus of 2nd embodiment of this invention. It is a characteristic view which shows the relationship between a top pulse width and (sigma) / DR. It is a characteristic view which shows the example of the set recording pulse conditions. It is a characteristic view showing an example of how to change the top pulse coefficient j and the off pulse coefficient k in the case of the minimum resolution Tc / 32. It is a characteristic view showing an example of how to change the top pulse coefficient j and the off pulse coefficient k in the case of the minimum resolution Tc / 64. It is explanatory drawing which shows the relationship between the conditions where the linearity of off pulse width Toff of 3rd embodiment of this invention is lose | eliminated, and spot diameter (phi). It is explanatory drawing which shows the example of a sampling process of the reproduction signal in a predetermined frequency. It is a schematic diagram for demonstrating the harmful effect accompanying the bad setting of a top pulse width. It is a schematic flowchart which shows the procedure of the recording condition optimization of 4th embodiment of this invention. It is a characteristic view which shows the example of the reproduction signal waveform of test data. FIG. 6 is a characteristic diagram showing a relationship between multi-value data m and reflected light intensity I when the recording power is changed. It is a characteristic view for demonstrating the method to determine the linearity of multi-value data and reflected light intensity. It is a characteristic view which shows the experimental result of the 6th Embodiment of this invention. It is a schematic flowchart which shows the procedure of the top pulse width determination for every multi-value data of 7th Embodiment of this invention. It is a characteristic view which shows the result of having performed test recording.

Explanation of symbols

6 Optical disc

Claims (33)

An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first step of sequentially recording the first test data by changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data;
A second step of determining the optimum top pulse width Ton from the monitoring result;
A third step of determining an optimum off pulse width Toff corresponding to the multi-value data from the monitoring result at the optimum top pulse width Ton determined in the second step;
Using the optimum top pulse width Ton and the optimum off-pulse width Toff determined in the second and third steps, the second test data is test-recorded by sequentially changing the recording power, and the second test data is recorded as the second test data. A fourth step of monitoring the corresponding reflected light intensity and determining the optimum recording power from the monitoring result;
An information recording method comprising:   2. The information recording method according to claim 1, wherein in the second step, the shortest top pulse width Ton at which the monitored reflected light intensity reaches a saturation value is determined as the optimum top pulse width. In the second step, the relational expression between the off-pulse width Toff and the reflected light intensity I for each top pulse width Ton from the monitored result I = a · Toff ³ + b · Toff ² + c · Toff + d
2. The information recording method according to claim 1, wherein the top pulse width Ton that minimizes the absolute value of the coefficient c is determined as the optimum top pulse width. In the third step, when the multi-value data m is test-recorded, the off-pulse width is Toff (m), the reflected light intensity at this time is I (m), and the coefficient is α, the optimum according to the multi-value data m The off-pulse width Toff opt (m) is expressed by the relational expression Toff opt (m) = α · (I (m) −L (m)) / (I (M + 1)
−I (m)) / (Toff (m + 1) −Toff (m)) + Toff (m)
The information recording method according to claim 1, wherein the information recording method is set by using. In the third step, the optimum off-pulse width Toff (m) corresponding to the multi-value data m is expressed by a relational expression I (m) = a · Toff (m) between the off-pulse width Toff (m) and the reflected light intensity I (m). ³ + b · Toff (m) ² + c · Toff (m) + d
The information recording method according to claim 1, wherein the information recording method is set by using. In the first step, the relational expression between the off pulse width Toff and the reflected light intensity I for each top pulse width Ton from the monitored result I = a · Toff ³ + b · Toff ² + c · Toff + d
And the coefficients a, b, c, d are approximated as a function of the top pulse width Ton, the Toff-reflected light intensity curve at the top pulse width Ton is predicted, and the shortest top pulse at which the reflected light intensity I becomes a saturation value. 2. The information recording method according to claim 1, wherein the width Ton is determined as an optimum top pulse width. In the first step, the relational expression between the off pulse width Toff and the reflected light intensity I for each top pulse width Ton from the monitored result I = a · Toff ³ + b · Toff ² + c · Toff + d
And the coefficients a, b, c, and d are approximated as a function of the top pulse width Ton, the Toff-reflected light intensity curve at the top pulse width Ton is predicted, and the off-pulse width Toff and the reflected light intensity I are approximately linear. 2. The information recording method according to claim 1, wherein a top pulse width Ton is set for each multi-value data.   8. In the fourth step, test recording is performed after setting a recording pulse, and a recording power that minimizes a deviation in reflected light intensity I is determined as an optimum recording power. Information recording method. An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
An information recording method, wherein a top pulse width Ton (m) and an off pulse width Toff (m) corresponding to the multi-value data m are both set to be an integral multiple of the unit time T. An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
An information recording method, characterized in that the off-pulse width Toff is an integral multiple of the unit time T and is increased substantially linearly with an increase in recording mark. An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
The off-pulse width Toff is an integral multiple of the unit time T and is increased approximately linearly as the recording mark increases, and the top pulse width Ton is an integral multiple of the unit time T and recording corresponding to each multi-value data An information recording method characterized by changing to a predetermined time according to an increase in the mark.   The top pulse width Ton is increased with respect to the recording mark whose reflected light intensity shows the maximum level from the substantially intermediate level in the multi-value data, and the recording mark whose reflected light intensity shows the minimum level from the intermediate level. 12. The information recording method according to claim 9, wherein the recording pulse is set so that the top pulse width Ton is substantially the same time. When the multi-value data m is an integer value greater than or equal to 0 that increases with an increase in recording marks,
The top pulse width Ton (m) and the off pulse width Toff (m) with respect to a unit time obtained by dividing the cell period Tc, which is the period of the recording mark, into n equal parts (n is a fixed value) = j × Tc / n (j is an integer value) is satisfied, and the off-pulse width Toff (m) = k × Tc / n (k is an integer value) is set, and the top pulse coefficient j is substantially linear. In addition, the off pulse coefficient k is increased for recording marks whose reflected light intensity shows a maximum level from a substantially intermediate level in the multi-valued data, and the reflected light intensity shows a minimum level from the intermediate level. 13. The information recording method according to claim 9, wherein the marks are set to substantially the same value.   The top pulse coefficient j and the off pulse coefficient k corresponding to an integral multiple of the period Tc / n are selected so that the intensity of the reflected light from the optical disk corresponding to the multi-value data m becomes a desired level. 14. The information recording method according to any one of claims 9 to 13, wherein:   When the multi-value data m is an integer value greater than or equal to 0 that increases as the number of recording marks increases, the top pulse coefficient j is set to the recording mark whose reflected light intensity has the minimum level in the multi-value data. 15. The information recording method according to claim 9, wherein the information recording method is set so as to increase. An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
When setting the top pulse width Ton and off-pulse width Toff corresponding to multi-value data, the recording mark length for each multi-value data with respect to the cell length of the spot diameter (relative intensity 1 / e ² ) on the recording layer used for recording and reproduction In the information recording method, the top pulse width Ton is increased with respect to a recording mark of a predetermined value or more when is less than a predetermined value.   17. The information recording according to claim 16, wherein the recording mark length corresponding to the multi-value data for increasing the top pulse width Ton is set to about 1/4 or less of the spot diameter on the recording layer used for recording and reproduction. Method.   17. The information recording method according to claim 1, wherein the target optical disc is a phase change optical recording medium.   19. The information recording method according to claim 18, wherein the recording layer of the target phase change optical recording medium is made of Ag-In-Sb-Te. An information recording apparatus for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first means for test-recording first test data by sequentially changing the top pulse width Ton, and monitoring reflected light intensity corresponding to the first test data;
A second means for determining the optimum top pulse width Ton from the monitoring result;
A third means for respectively determining an optimum off-pulse width Toff corresponding to the multi-value data from the monitoring result at the optimum top pulse width Ton determined by the second means;
Using the optimum top pulse width Ton and the optimum off-pulse width Toff determined by the second and third means, the second test data is test-recorded by changing the recording power sequentially, and the second test data. A fourth means for monitoring the reflected light intensity corresponding to, and determining the optimum recording power from the monitoring result;
An information recording apparatus comprising: An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw recorded in advance on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Steps,
Using the read top pulse width Ton, off-pulse width Toff, and the ratio ε of the erase power Pe and the recording power Pw, the recording power is sequentially changed to test-record the first test data. A second step of monitoring the corresponding reflected light intensity;
A third step of determining the optimum recording power Pw from the monitoring result;
An information recording method comprising: In the third step, a relational expression between the multi-value data m and the reflected light intensity I is obtained from the monitored result I = a · m ² + b · m + c
22. The information recording method according to claim 21, wherein the recording power that minimizes the coefficient a is determined as the optimum recording power. An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw recorded in advance on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Steps,
Using the read top pulse width Ton, off-pulse width Toff, and the ratio ε of the erase power Pe and the recording power Pw, the recording power is sequentially changed to test-record the first test data. A second step of monitoring the corresponding reflected light intensity;
From the monitoring result, a third step for determining the optimum recording power,
A fourth step of obtaining a relational expression I = a · m + b between the multi-value data m and the reflected light intensity I from the monitor result at the optimum recording power and calculating the square r ² of the correlation coefficient r;
A fifth step of determining linearity between the multi-value data m and the reflected light intensity I using the r ² ;
A sixth step in which the first test data is test-recorded by sequentially changing the off-pulse width Toff, and the reflected light intensity corresponding to the first test data is monitored;
A seventh step of determining an optimum off-pulse width Toff according to the multi-value data from the monitoring result;
An information recording method comprising: An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw recorded in advance on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Steps,
A second step of sequentially recording the first test data by changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data;
From the monitoring result, a third step for determining the optimum recording power,
A fourth step of obtaining a relational expression I = a · m + b between the multi-value data m and the reflected light intensity I from the monitor result at the optimum recording power and calculating the square r ² of the correlation coefficient r;
A fifth step of determining linearity between the multi-value data m and the reflected light intensity I using the r ² ;
Using the optimum recording power determined in the third step, the top pulse width Ton is successively changed to test record the first test data, and the reflected light intensity corresponding to the first test data is monitored. When,
A seventh step of determining the optimum top pulse width from the monitoring result;
An eighth step of determining an optimum off pulse width corresponding to the multi-value data from the monitor result at the optimum top pulse width determined in the seventh step;
An information recording method comprising: An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw recorded in advance on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Steps,
Using the read recording power and ε, a first test data is test-recorded by successively changing the top pulse width Ton and the off-pulse width Toff, and the reflected light intensity corresponding to the first test data is monitored. Steps,
A third step of determining an optimum top pulse width and an optimum off-pulse width according to the multi-value data from the monitoring result;
An information recording method comprising: An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw recorded in advance on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Steps,
Using the read recording power, ε, and top pulse width Ton, the second test pulse is recorded by sequentially changing the off-pulse width Toff, and the reflected light intensity corresponding to the first test data is monitored. Steps,
A third step of determining an optimum off-pulse width according to the multi-value data from the monitoring result;
Using the read ε and the optimum off-pulse width determined in the third step, the second test data is test-recorded by successively changing the recording power, and the reflected light intensity corresponding to the second test data is monitored. A fourth step of determining the optimum recording power from the monitor result;
An information recording method comprising: An information recording method for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw recorded in advance on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Steps,
Using the read recording power, ε, and off-pulse width Toff, the top pulse width Ton is successively changed to test-record the first test data, and the reflected light intensity corresponding to the first test data is monitored. Steps,
A third step of determining an optimum top pulse width according to the multi-value data from the monitoring result;
An information recording method comprising:   The information recording method according to any one of claims 21 to 27, wherein the determined optimum recording parameter is recorded in a storage device of the information recording device. An information recording apparatus for recording a recording mark corresponding to multi-value data on an optical disc with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse,
A first recording parameter is read which includes a recording power Pw pre-recorded on the optical disc, a ratio ε of the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off pulse width Toff corresponding to multi-value data. Means,
A second means for test-recording the first test data by sequentially changing the top pulse width Ton and monitoring the reflected light intensity corresponding to the first test data;
A third means for determining the optimum recording power from the monitoring result;
A fourth means for obtaining a relational expression I = a · m + b between the multi-value data m and the reflected light intensity I from the monitor result at the optimum recording power and calculating the square r ² of the correlation coefficient r;
A fifth means for determining linearity between the multi-value data m and the reflected light intensity I using the r ² ;
Using the optimum recording power determined in the third step, the top pulse width Ton is sequentially changed to test record the first test data, and the reflected light intensity corresponding to the first test data is monitored. Means,
A seventh means for determining the optimum top pulse width from the monitoring result;
An eighth means for determining an optimum off-pulse width corresponding to the multi-value data from the monitor result at the optimum top pulse width determined by the seventh means;
An information recording apparatus comprising:   30. The information recording apparatus according to claim 29, wherein the determined optimum recording parameter is recorded in a storage device. Recording marks are recorded on the recording layer with a predetermined recording power using a recording pulse composed of a set of top pulse, off pulse, and erasing pulse so that the reproduction signal level changes in multiple steps according to the multilevel data. An optical disc recorded in units,
A recording parameter including at least a recording power Pw, a ratio ε between the erasing power Pe and the recording power Pw, and a top pulse width Ton and an off-pulse width Toff corresponding to multi-value data is recorded in advance. Optical disc to play.   A program comprising instructions for causing a computer to execute the steps of the information recording method according to any one of claims 1 to 19, 21 to 28. A computer-readable recording medium on which the program according to claim 32 is recorded.

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