JP2007287229A - Recording strategy adjusting system, and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize automatically recording strategy in an optical disk device. <P>SOLUTION: A system controller 32 writes test data as a test with various recording strategy using a test area of an optical disk 10, and selects optimum recording strategy by evaluating reproduced signal quality of the test data. In the system controller 32, an evaluation value Hst is calculated by Hst=A×Eb<SP>2</SP>+B×We<SP>2</SP>+C×(Peb-Pmb)<SP>2</SP>in accordance with difference for each recording strategy of the error rate minimum value Eb, recording power range We in which a threshold error rate is obtained, recording power Pmb in which target value is obtained, and recording power Peb, and recording strategy in which the minimum Hst is obtained is defined as the optimum recording strategy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording strategy adjustment system applied to an optical disc apparatus, and more particularly to optimization of a recording strategy.

  In an optical disc apparatus that records data on a recordable / reproducible optical disc such as a CD-R, DVD-R, or DVD-RW, it is necessary to optimize the recording strategy for each optical disc, and it has been proposed to automate this optimization. ing.

  Patent Document 1 below discloses that two types of asymmetry values 11T and 3T, 11T and 4T are examined, and the recording strategy is adjusted based on the magnitude relationship and the absolute value. Specifically, the recording power is set to 5 levels in the range of ± 30% around the disc information value, and the pulse width Tmp (intermediate pulse width) is set to 3 levels in the range of ± 0.1 T around the disc information value. Then, 9 out of 15 combinations of recording power and pulse width Tmp are set, and test recording is performed in units of one sync frame for each of 11T and 3T and 11T and 4T combinations. It is disclosed that the β value of each sync frame is measured from each test recording signal, the asymmetry value β1 and the asymmetry value β2 are acquired, and the optimum condition is searched using the measured β1 and β2.

  Further, the following Patent Document 2 describes a recording power that minimizes jitter including all recording marks or only the shortest recording mark, and recording power that minimizes a deviation from the theoretical value of the longest recording mark. It is disclosed that the recording strategy is selected to be substantially equal.

JP 2003-157534 A JP 2000-30254 A

  Thus, paying attention to the asymmetry value and jitter, and automatically optimizing the recording strategy by selecting a recording strategy in which these values are desired values as the optimum recording strategy (automatic tuning of the recording strategy) However, there are a wide range of parameters for evaluating each recording strategy, and in addition to the jitter and asymmetry described above, there are error rates and β values. The situation is not reached.

  The present invention has been made in view of the above-described problems of the prior art. The object of the present invention is to make it possible to more easily and reliably determine the superiority or inferiority of each recording strategy, and to automatically select the optimum recording strategy. It is to provide a system and apparatus that can be used.

  In the present invention, prior to data recording, trial writing means for trial writing test data by changing a recording strategy and recording power in a test area of the optical disc, and evaluation of a reproduction signal quality obtained by reproducing the test data And optimizing means for selecting an optimum recording strategy and recording means for recording data on the optical disc with the optimized recording strategy, and the reproduction signal quality includes an error rate or jitter, and the optimum A power range in which an error rate or jitter below a threshold set in accordance with a minimum error rate or jitter among all error rates or jitters obtained by changing the recording strategy and recording power is obtained. Is detected for each recording strategy, and the optimum recording speed is selected according to the size of the power range. And selects the Strategies.

In one embodiment of the present invention, the optimization means sets the power range size to We, the error rate minimum value or jitter minimum value for each recording strategy to Eb, and the target β for each recording strategy. When the recording power for obtaining the value, the target modulation degree or the target γ value is Pmb, and the recording power for obtaining the minimum error rate value or the minimum jitter value is Peb,
H = A · Eb ⁿ + B · We ⁿ + C · | Peb−Pmb | ⁿ
However, A and C are positive real numbers, B is a negative real number, and n is a recording strategy having the smallest evaluation value H given as a real number of 1 or more is selected as the optimum recording strategy.

In another embodiment of the present invention, the optimization means sets the power range to We, sets the error rate minimum value or jitter minimum value for each recording strategy to Eb, and sets the power range for each recording strategy. When the recording power for obtaining the target β value, the target modulation degree, or the target γ value is Pmb, the recording power for obtaining the minimum error rate value or the minimum jitter value is Peb, and the intermediate recording power of the power range is Pws,
H = A · Eb ⁿ + B · We ⁿ + C · | Peb−Pmb | ⁿ + D · | Peb−Pws | ⁿ
However, A, C, and D are positive real numbers, B is a negative real number, and n is a recording strategy having the smallest evaluation value H given as a real number of 1 or more, as the optimum recording strategy. For example, n can be set to 2.

  According to the present invention, the power at which an error rate or jitter below a threshold set according to the minimum error rate or minimum jitter among all error rates or jitters obtained by changing the recording strategy and recording power can be obtained. By detecting the range for each recording strategy and selecting the optimum recording strategy according to the size of the power range, the optimum recording strategy can be automatically selected with high accuracy.

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

  FIG. 1 shows an overall configuration diagram of an optical disc apparatus according to the present embodiment. A recordable optical disk 10 such as a DVD ± R, a DVD ± RW, a DVD-RAM, or a next-generation optical disk (Blu-ray or HD-DVD) is rotated by a spindle motor (SPM) 12. The spindle motor SPM 12 is driven by a driver 14, and the driver 14 is servo-controlled by a servo processor 30 so as to have a desired rotation speed.

  The optical pickup 16 includes a laser diode (LD) for irradiating the optical disk 10 with laser light and a photodetector (PD) that receives reflected light from the optical disk 10 and converts it into an electrical signal, and is disposed opposite to the optical disk 10. . The optical pickup 16 is driven in the radial direction of the optical disk 10 by a thread motor 18, and the thread motor 18 is driven by a driver 20. The driver 20 is servo-controlled by the servo processor 30 similarly to the driver 14. The LD of the optical pickup 16 is driven by a driver 22, and the driver 22 is controlled by an auto power control circuit (APC) 24 so that the drive current becomes a desired value. The APC 24 and the driver 22 control the light emission amount of the LD according to a command from the system controller 32. Although the driver 22 is provided separately from the optical pickup 16 in the figure, the driver 22 may be mounted on the optical pickup 16 as described later.

  When data recorded on the optical disk 10 is reproduced, a laser beam of reproduction power is irradiated from the LD of the optical pickup 16, and the reflected light is converted into an electric signal by the PD and output. A reproduction signal from the optical pickup 16 is supplied to the RF circuit 26. The RF circuit 26 generates a focus error signal and a tracking error signal from the reproduction signal and supplies them to the servo processor 30. The servo processor 30 servo-controls the optical pickup 16 based on these error signals, and maintains the optical pickup 16 in an on-focus state and an on-track state. Further, the RF circuit 26 supplies an address signal included in the reproduction signal to the address decoding circuit 28. The address decoding circuit 28 demodulates the address data of the optical disk 10 from the address signal and supplies it to the servo processor 30 and the system controller 32.

  One example of the address signal is a wobble signal. A wobble signal is wobbled by a modulated signal of time information indicating the absolute address of the optical disc 10, and the wobble signal is extracted from the reproduction signal and decoded to decode the address data (ATIP ) Can be obtained. Further, the RF circuit 26 supplies the reproduction RF signal to the binarization circuit 34. The binarization circuit 34 binarizes the reproduction signal and supplies the obtained signal to the encoding / decoding circuit 36. The encode / decode circuit 36 demodulates the binary signal and corrects errors to obtain reproduction data, and outputs the reproduction data to a host device such as a personal computer via the interface I / F 40. When the reproduction data is output to the host device, the encoding / decoding circuit 36 temporarily stores the reproduction data in the buffer memory 38 and outputs it.

  When recording data on the optical disk 10, data to be recorded from the host device is supplied to the encode / decode circuit 36 via the interface I / F 40. The encode / decode circuit 36 stores data to be recorded in the buffer memory 38, encodes the data to be recorded, and supplies the data to the write strategy circuit 42 as modulated data. The write strategy circuit 42 converts the modulation data into a multi-pulse (pulse train) according to a predetermined recording strategy, and supplies it to the driver 22 as recording data. Since the recording strategy affects recording quality, optimization is performed prior to data recording. That is, test data is test-written by changing the recording strategy in a predetermined test area of the optical disc 10, and the test data that has been test-written is reproduced and its signal quality is evaluated. Then, an optimum recording strategy is selected based on the evaluation result. The laser light whose power is modulated by the recording data is irradiated from the LD of the optical pickup 16 and the data is recorded on the optical disk 10. After recording the data, the optical pickup 16 reproduces the recorded data by irradiating a laser beam with a reproduction power, and supplies it to the RF circuit 26. The RF circuit 26 supplies the reproduction signal to the binarization circuit 34, and the binarized data is supplied to the encode / decode circuit 36. The encode / decode circuit 36 decodes the modulated data and collates it with recorded data stored in the buffer memory 38. The result of the verification is supplied to the system controller 32. The system controller 32 determines whether to continue recording data or execute a replacement process according to the result of verification.

  The system controller 32 controls the operation of the entire system, and particularly performs OPC (OPtimum Power Control) prior to recording and optimization of the recording strategy. In OPC, test data is trial-written in a test area of the optical disc 10 while changing the recording power stepwise, and the test data that has been trial-written is reproduced and its β value, γ value, modulation factor, error rate, etc. are measured. . Then, the recording power at which the reproduction signal quality such as the error rate becomes a desired value is selected and set as the optimum recording power Po. The system controller 32 controls the driver 22 so that the selected recording power Po is obtained. In the optimization of the recording strategy, test data is test-written by changing the recording strategy for each type of the optical disc 10, the test data is reproduced, the error rate is measured, and each recording strategy is evaluated according to a specific evaluation standard. .

  FIG. 2 shows a recording strategy when the optical disc 10 is a CD-R. FIG. 2A shows recording data, which has a data length of 3T to 11T. FIG. 2B shows a recording strategy corresponding to the recording data. The peak power Pk and the powered power Pp exist as parameters for the power level, and SPT, SPTW, EPM, and TWT exist as parameters for the pulse width. SPT is a pulse start timing, SPTW is a pulse width of a powered pulse, EPM is a pulse end timing, and TWT is a pulse width. The recording strategy is composed of these parameters, and the recording strategy can be changed by changing these parameters. In this embodiment, the recording strategy is changed by changing the pulse width TWT and the pulse width SPTW of the powered pulse.

  Table 1 shows the TWT changing method, and Table 2 shows the SPTW changing method.

  In Table 1, “4X” indicates that the rotational speed is quadruple speed. Since the optimum recording strategy can be changed for each rotation speed and each data length, the TWT is changed within a predetermined range for each rotation speed and each data length. The table shows an increase / decrease with respect to a reference pulse width (recommended pulse width for each optical disc 10 and recorded in advance on the optical disc 10). For example, in the case of quadruple speed, in the data length of 3T, the TWT is changed with a width of 0.1T from −1.2T to −0.2T with respect to the reference pulse width. That is, 12 steps are changed. In the case of 4T data length, TWT is changed from 0T to 0.1T with respect to the pulse width in the case of 3T. The same applies to Table 2. Optimization is performed for each data length. As an optimization procedure, first, regarding the data length 3T, the SPTW is fixed to a certain value, the TWT is changed and evaluated, and the optimum TWT is selected. Next, a recording strategy consisting of an optimal (TWT, SPTW) pair is selected by fixing the optimal TWT and changing the SPTW. Of course, it is possible to evaluate all the recording strategies composed of possible (TWT, SPTW) pairs and select the optimum (TWT, SPTW) pair. After selecting the optimum recording strategy for the data length 3T, the TWT and SPTW are increased or decreased with the optimum recording strategy for the data length 3T as the center value for the data length 4T to change the recording strategy, and the optimum recording strategy is selected. The same applies to data lengths of 5T or more.

  FIG. 3 shows a recording strategy when the optical disk 10 is DVD ± R. This is a multi-pulse type recording strategy. FIG. 3A shows recording data, which has a data length of 3T to 14T. 3B and 3C show recording strategies corresponding to the recording data, FIG. 3B shows the pulse width, and FIG. 3C shows the start or end timing of the pulse. In the present embodiment, the recording strategy is changed by changing the pulse width Ttop of the leading pulse and the pulse width Tmp of the intermediate pulse. Note that 0.5T + Tslp, which is the pulse width of the final pulse, is set to the same value as Tmp. The cooling pulse Tcl is set to zero. Ttop is changed with a width of 0.025T from 1.5T to 1.7T, and Tmp is changed with a width of 0.025T from 0.6T to 0.725T.

  FIG. 4 shows another recording strategy when the optical disk 10 is a DVD ± R. This is a castle type recording strategy. FIG. 4A shows recording data, which exists from 3T to 14T. 4B and 4C are recording strategies corresponding to the recording data, FIG. 4B shows the pulse width, and FIG. 4C shows the start or end timing of the pulse. Note that 3T data is recorded with another recording strategy consisting of a single pulse. The recording strategy is changed by changing the 3T pulse width from 1.5T to 2.1T. In the figure, the ratio between the peak power level P1 and the powered power P2 is fixed and P1: P2 = 6: 4. The pulse width nTtop of the start pulse and the pulse width Tlp of the end pulse are the same, and when the data length is 4T, the end timing Ttr of the start power pulse and the start timing Lld of the end power pulse are adjusted to 0.1T, 0 Shorten about 2T. When the data length is 5T or more, the recording strategy is changed by changing nTop from 0.6T to 1.2T.

  In FIG. 4, when the data length is 3T, a multi-pulse, 4T or more is a castle type (this is referred to as a 3T monocastle type). It is good also as a castle type (this is called 3T4T mono castle type). Also, which recording strategy pattern of FIG. 3 or FIG. 4 is used may be determined according to the rotational speed. For example, a multi-pulse type is selected for standard speed (1X) and double speed (2X), a 3T monocastle type is selected for quadruple speed (4X), and a 3T4T monocastle type is selected for higher speeds.

  As described above, test recording is performed by changing the recording strategy by using a different recording strategy for each type of the optical disc 10 and changing the pulse width in each recording strategy according to the data length and rotation speed. To do.

  FIG. 5 shows a processing flowchart of the present embodiment. When it is necessary to read the information recorded in advance on the mounted optical disk 10 and optimize the recording strategy in the test area of the optical disk 10, it is first determined whether or not all strategies have been tried (S101). If all the strategies have not been tried yet, one of the recording strategies corresponding to the type of the mounted optical disk 10 is selected (S102). For example, when the optical disc 10 is a CD-R, the basic recording strategy is the strategy shown in FIG. 2, and one recording strategy is selected from a recording strategy group generated by variously changing TWT and SPTW. .. Are numbered as 1, 2, 3,... For each recording strategy that constitutes a recording strategy group generated by variously changing TWT and SPTW, and are selected from the smallest number. The selected recording strategy is, for example, a strategy in which TWT = reference length−1.2T and SPTW = reference length + 1.3T when the rotational speed is quadruple speed and the data length is 3T. A recording strategy group is generated for each type of optical disk 10 (CD-R, DVD-R, DVD + R, etc.) and for each rotation speed. In the following description, CD-R is used as the optical disk 10 and quadruple speed is used as the rotation speed. I will explain.

  After selecting a recording strategy in S102, test data is written on a trial basis by changing the recording power in the recording strategy (S103). For example, test data is test-written by changing the recording power in seven steps (P1 to P7). After test writing the test data, the test data is reproduced and its signal quality is measured. The signal quality is a β value and an error rate (S104). After reproducing the test data and measuring its β value and error rate, a relational expression between the recording power P and the β value is calculated, and a recording power Pmb for obtaining the target β value is calculated from this relational expression. Further, a relational expression between the recording power P and the error rate is calculated, and a recording power Peb and a minimum value Eb of the error rate are calculated from the relational expression (S105). Even if the power closest to the target β value is selected from P1 to P7 without calculating the relational expression, or the power that minimizes the error rate and the error rate at that time are selected from P1 to P7 Good. Although the relational expression is an approximate expression, a quadratic approximation or a higher-order approximation may be used. As will be described later, when considering the influence of thermal interference, higher-order approximation is desirable, and second-order approximation may be used as long as thermal interference is negligible. The above processing is executed for all the recording strategies belonging to the recording strategy group, and Pmb, Peb, and Eb are detected for each recording strategy.

  After detecting Pmb, Peb, and Eb for all the recording strategies obtained by changing TWT and SPTW when driving the CD-R at 4 × speed, the minimum error rate Ebmin in all the recording strategies is set. At the same time, for each recording strategy, a recording power range We that is equal to or less than a threshold (Ebmin + α) increased by a predetermined amount α with respect to the detected minimum error rate Ebmin is detected (S106).

  FIG. 6 shows the relationship between the recording power P and the β value in a certain recording strategy. The relationship between the recording power P and the β value is first-order approximated (linear approximation), and the recording power Pmb at which the target β value (value stored in advance on the optical disc 10) is obtained is detected.

  FIG. 7 shows the relationship between the recording power P and the error rate in a certain recording strategy. The threshold set by quadratic approximation of the relationship between the recording power P and the error rate E and the minimum error rate Eb, the recording power Peb for obtaining the minimum error rate Eb, and the minimum error rate Ebmin among all the recording strategies. A recording power range We in which an error rate equal to or less than the value (Ebmin + α) is detected.

Returning to FIG. 5 again, after detecting the error rate minimum value Ebmin of all the recording strategies and the power range We for each recording strategy, the test data of each recording strategy is determined using these parameters Pmb, Peb, Eb, We. Evaluate the playback signal quality. The evaluation value Hst is given by the following evaluation function.
Hst = A · Eb ⁿ + B · We ⁿ + C · | Peb−Pmb | ⁿ
Here, A and C are positive real numbers, B is a negative real number, and n is a real number of 1 or more. The smaller the error rate minimum value Eb, the better the quality, the wider the recording power range We, the better, and the smaller the difference between Peb and Pmb, the better. The evaluation value Hst becomes smaller as Eb is smaller, We is larger, and the difference between Peb and Pmb is smaller. Therefore, a recording strategy with a smaller value of Hst is a recording strategy with excellent reproduction quality. A, B, and C are constants and are stored in advance in the memory of the system controller 32. Similarly, n is stored in advance in the system controller 32. For example, n = 2 is preferable. In this case, the evaluation value is
Hst = A · Eb ² + B · We ² + C · (Peb−Pmb) ²
It becomes. In the present embodiment, the evaluation value Hst is calculated for each recording strategy with A = 1000, B = -100, C = 10, and n = 2 (S107). As can be seen from the above equation, it should be noted that the optimum recording strategy is selected in consideration of the recording power range We, rather than simply selecting a recording strategy with a low error rate. More simply, Hst = A · Eb ² + B · We ²
Or Hst = B · We ⁿ + C · | Peb−Pmb | ⁿ
It is also possible to calculate the evaluation value Hst.

  After calculating the evaluation value Hst for each recording strategy, the system controller 32 selects the recording strategy having the smallest Hst as the optimum recording strategy (S108), and ends the recording strategy optimization process. After selecting the optimum recording strategy, data is recorded in the data area of the optical disc 10 with the optimum recording strategy (S109).

FIG. 8 shows an example of the evaluation value Hst calculated for each recording strategy. In the figure, the horizontal axis indicates the number of each numbered recording strategy, and the vertical axis indicates the evaluation value Hst. The evaluation value Hst is
Hst = 1000 Eb ² −100 We ² +10 (Peb−Pmb) ²
It is calculated by.

  In each recording strategy, the SPTW with a data length of 3T was fixed at 1.59375T, the SPTW with a data length of 4T or more was fixed at 1.625T, and the TWT was changed as follows.

  In the table, “3Ttwt” indicates a TWT having a data length of 3T. Recording strategies exist from strategy 1 to strategy 28. FIG. 8 shows the evaluation values Hst of these 28 recording strategies. Strategy 1 has the smallest evaluation value Hst.

  FIG. 9 shows the evaluation value Hst of each recording strategy when TWT = −1.1875T obtained in FIG. 8 is fixed and SPTW is changed as follows.

  In the table, “3Tsptw” indicates SPTW with a data length of 3T. There are recording strategies from strategy 1 to strategy 24. As can be seen from FIG. 9, strategy 11 has the smallest evaluation value Hst. Therefore, the strategy 11 having the smallest evaluation value Hst is selected as the optimum strategy at the rotation speed of 4 ×.

  In this example, an algorithm that first optimizes TWT and then optimizes SPTW is used. However, as described above, a recording strategy composed of combinations of possible (TWT, SPTW) with respect to data length 3T. For each recording strategy of the group, the evaluation value Hst may be calculated to select a recording strategy that provides the minimum Hst, and then the same processing may be repeated for a data length of 4T or more. After the optimum recording strategy (3T) with a data length of 3T, the optimum recording strategy (4T) with a data length of 4T, and so on are selected, the optimum recording strategy for each T is combined and the optimum recording at a specific double speed of the optical disc 10 is performed. A strategy is constructed.

  As described above, in this embodiment, the power range in which a predetermined error rate can be obtained is considered, and the total of the recording power that obtains the error rate and the target β value and the recording power that obtains the minimum error rate is also considered. In particular, it is possible to automatically select a recording strategy having excellent reproduction signal quality.

In the present embodiment, the relationship between the recording power P and the error rate E is second-order approximated. However, when thermal interference cannot be ignored, it is preferable to use a higher-order approximation as described above. If thermal interference cannot be ignored,
Hst = A · Eb ² + B · We ² + C · (Peb−Pmb) ²
It is preferable to add a term for taking into account the influence of thermal interference, instead of calculating the evaluation value by the above.

FIG. 10 shows the relationship between the recording power and the error rate when thermal interference occurs. The error rate is not symmetric with respect to the recording power, and the error rate suddenly deteriorates (increases) at high recording power and becomes asymmetrical. In such a case, as shown in FIG. 11, in addition to the recording power range We that is equal to or less than the threshold value (Ebmin + α), the intermediate power Pws in the recording power range is detected, and the difference between the intermediate power Pws and Peb is taken into consideration. To do. Specifically, the evaluation value Hst is
Hst = A · Eb ⁿ + B · We ⁿ + C · | Peb−Pmb | ⁿ
+ D · | Pws−Peb | ⁿ
And D is a positive real number. The fourth term on the right side is a term corresponding to thermal interference, newly added. If n = 2,
Hst = A · Eb ² + B · We ² + C · (Peb−Pmb) ²
+ D · (Pws-Peb) ²
It is.

  In this embodiment, the error rate is used as the reproduction signal quality of the test data. However, jitter may be used instead of the error rate. In this case, Pe is set to the recording power that minimizes the jitter, Eb is set to the minimum jitter value, Ebmin is set to the minimum jitter value in all the recording strategies, and We is set to a recording power range in which jitter below the threshold value can be obtained. . The threshold value is given by Ebmin + δ (δ is a predetermined value).

  Further, the modulation degree and the γ value may be used instead of the β value. When the modulation degree is used, Pmb is a recording power at which the target modulation degree is obtained. Incidentally, the β value is defined as β = (A−B) / (A + B) where A is the peak level of the reproduction RF signal coupled with RC and B is the bottom level. Jitter is a phase difference between the binarized signal of the reproduction RF signal and the synchronous clock signal. The modulation degree m is defined as m = C−D / (C + D) where C is the peak level and D is the bottom level of a certain data length (eg, 11T) of the reproduction RF signal. The γ value is the rate of change of the degree of modulation m.

  In the present embodiment, the recording strategy changing method has been described by taking the CD-R as an example, but the recording strategy can be arbitrarily changed. For example, in the present embodiment, in the castle type recording strategy shown in FIG. 4, the recording strategy is changed by changing nTop and Tlp, and other parameters such as the cooling pulse Tcl and the start powered pulse start timing Tld are as follows: Although the reference value (or recommended value) stored in advance on the optical disk 10 is used, any parameter can be changed. The parameter to be changed may be designated. In DVD-R, when the data length is 3T, 4T, a single pulse, 5T or more is used as the castle type recording strategy shown in FIG. 4, and the recording strategy is changed for all data lengths, while in DVD + R, the data length is changed. Only 3T may be a single pulse, 4T or more, and the castle type recording strategy shown in FIG. 4 may be used, and for 3T, the recording strategy recommended by the optical disc may be used as it is, and the recording strategy may be changed for 4T or more.

1 is a block diagram illustrating a configuration of an optical disc device. It is a recording strategy explanatory diagram in the case of CD-R. FIG. 4 is an explanatory diagram of a recording strategy (multi-pulse type) in the case of DVD-R. It is explanatory drawing of the recording strategy (castle type) in the case of DVD-R. It is a processing flowchart of an embodiment. It is a graph which shows the relationship between the recording power and β value in a certain recording strategy. It is a graph which shows the relationship between the recording power and error rate in a certain recording strategy. It is a graph which shows the relationship between a strategy and an evaluation value. It is a graph which shows the relationship between a strategy and an evaluation value. It is a graph which shows the relationship between recording power and error rate when there is thermal interference. It is Pws explanatory drawing for evaluation value calculation in case there exists thermal interference.

Explanation of symbols

  10 optical disk, 32 system controller, 42 write strategy circuit.

Claims (9)

Prior to data recording, trial writing means for trial writing test data by changing the recording strategy and recording power in the test area of the optical disc;
Optimizing means for selecting an optimal recording strategy by evaluating reproduction signal quality obtained by reproducing the test data;
Recording means for recording data on the optical disc with an optimized recording strategy;
Have
The playback signal quality includes error rate or jitter,
The optimization means obtains an error rate or jitter below a threshold set according to a minimum error rate or minimum jitter among all error rates or jitters obtained by changing the recording strategy and recording power. A recording strategy adjustment system, wherein a power range is detected for each recording strategy, and an optimum recording strategy is selected according to the size of the power range. The system of claim 1, wherein
The optimization means selects an optimal recording strategy according to the size of the power range for each recording strategy and the size of the minimum error rate or the minimum jitter value for each recording strategy. Recording strategy adjustment system. The system of claim 1, wherein
The reproduction signal quality includes a β value, a modulation degree, or a γ value,
The optimization means includes a size of the power range for each recording strategy, a recording power for obtaining a target β value, a target modulation degree, or a target γ value for each recording strategy and a minimum error rate value or a minimum jitter value. A recording strategy adjustment system, wherein an optimum recording strategy is selected in accordance with the magnitude of the difference in recording power obtained. The system of claim 1, wherein
The reproduction signal quality includes a β value, a modulation degree, or a γ value,
The optimization means includes a size of the power range for each recording strategy, a size of a minimum error rate value or a jitter minimum value for each recording strategy, and a target β value, a target modulation degree, or a target for each recording strategy. A recording strategy adjusting system, wherein an optimum recording strategy is selected in accordance with a difference between a recording power at which a γ value is obtained and a recording power at which an error rate minimum value or a jitter minimum value is obtained. The system of claim 4, wherein
The optimization means further selects an optimum recording strategy in accordance with the magnitude of the difference between the intermediate recording power in the power range for each recording strategy and the recording power at which the error rate minimum value or jitter minimum value is obtained. Characteristic recording strategy adjustment system. The system of claim 4, wherein
The optimization means sets the power range size to We, the error rate minimum value or jitter minimum value for each recording strategy to Eb, and the target β value, target modulation factor or target γ value for each recording strategy. Is Pmb and the recording power at which the error rate minimum value or the jitter minimum value is obtained is Peb,
H = A · Eb ⁿ + B · We ⁿ + C · | Peb−Pmb | ⁿ
However, A and C are positive real numbers, B is a negative real number, and n is a recording strategy having the smallest evaluation value H given by a real number of 1 or more, as an optimum recording strategy. . The system of claim 5, wherein
The optimization means sets the power range size to We, the error rate minimum value or jitter minimum value for each recording strategy to Eb, and the target β value, target modulation degree, or target γ value for each recording strategy. Is Pmb, the recording power at which the error rate minimum value or the jitter minimum value is obtained is Peb, and the intermediate recording power in the power range is Pws.
H = A · Eb ⁿ + B · We ⁿ + C · | Peb−Pmb | ⁿ + D · | Peb−Pws | ⁿ
However, A, C, and D are positive real numbers, B is a negative real number, and n is a recording strategy having the smallest evaluation value H given as a real number of 1 or more as an optimal recording strategy. Adjustment system. The system according to any one of claims 6 and 7,
A recording strategy adjusting system, wherein n is 2.   An optical disc apparatus comprising the recording strategy adjustment system according to any one of claims 1 to 8.

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