JP4653779B2 - Recording condition determining method, optical disc recording / reproducing apparatus, and optical disc - Google Patents

Description

  The present invention relates to a technique for determining recording conditions for an optical disc.

  Conventionally, recording is performed by changing the recording power Pw (also referred to as main recording power) at the time of mark formation in a predetermined range to the test recording area of the optical disc, and reproducing the recording result in the test recording area. For example, a method is known in which an evaluation value such as β is calculated from the obtained reproduction signal, and an optimum recording power for the evaluation value satisfying a predetermined condition is derived. Further, the recording power Ps at the time of space formation other than the recording power Pw at the time of mark formation and the second recording power Pbw lower than the recording power at the time of mark formation are set as values of a constant ratio with respect to the main recording power Pw. Generally, it is set as a predetermined constant value.

Japanese Patent Application Laid-Open No. 2006-344251 discloses an optical disc recording technique that shortens the time for trial writing and has good reproduction quality when overwritten. Specifically, the ratio of recording power and erasing power is fixed, the recording power is changed, the test signal is recorded in the test writing area of the optical disc, reproduced, and the optimum recording power is calculated using the change curve of parameter γ. The erasing power is calculated from the calculated optimum recording power, the test signal is recorded in the trial writing area of the optical disc with the calculated optimum recording power and the calculated erasing power, and then the recording power with the calculated optimum recording power fixed. The test signal is overlaid and recorded on the trial writing area of the optical disc with the erase power changed, and the optimum erase power is calculated from the playback signal. Actual recording is performed with the calculated optimum record power and the calculated optimum erase power. The signal is overlaid on the recording area of the optical disc. The erasing power is considered, but the recording power at the time of forming the space is not considered.
JP 2006-344251 A

  Thus, in the prior art, much consideration has not been given to the recording power Ps at the time of forming the space. However, the recording power Ps at the time of forming the space plays a role as a bias power for controlling the thermal state immediately before the mark formation, and further, the thermal state needs to be controlled within a range where the mark formation is not performed. Thus, it is an important factor in determining the recording quality. That is, it is not a simple parameter that may be determined to be a constant ratio with respect to the main recording power Pw. Therefore, in the prior art, the recording power Ps at the time of forming an appropriate space is not used, and sufficient performance cannot be obtained with respect to the recording quality.

  Accordingly, an object of the present invention is to provide a technique for determining the recording power Ps when forming an appropriate space.

  Another object of the present invention is to provide a technique for improving the recording quality with respect to an optical disc using the recording power Ps at the time of forming an appropriate space.

  The recording condition determination method according to the present invention includes a recording step for writing to an optical disk for each of a plurality of recording powers at the time of forming a space, and a specific code in a reproduction signal obtained by reproducing the writing result in the recording step. A measurement step for measuring the amplitude, and an upper limit value setting step for calculating an upper limit value of the recording power at the time of forming the space using the measured amplitude of the specific code are included. According to the novel knowledge of the inventor of the present invention, the upper limit value of the recording power Ps at the time of space formation can be obtained by performing the above-described measurement. That is, the range of values to be used can be specified as the recording power Ps at the time of space formation.

  Further, the present invention may further include a set value calculating step for calculating a set value of the recording power at the time of forming the space based on the upper limit value of the recording power at the time of forming the space. Thus, if the upper limit value is obtained, the value to be set for the laser driver or the like can be determined.

  The present invention may further include an optimization step of performing a recording power optimization process at the time of mark formation after setting a setting value of the recording power at the time of space formation. According to the novel knowledge of the inventor of the present invention, the method of making the recording power Ps at the time of forming the mark depend on the recording power Pw at the time of forming the mark as in the prior art is not preferable. If the recording power Pw at the time of mark formation is optimized after setting the power Ps to an appropriate value, the recording quality can be improved.

  Further, the amplitude of the specific code described above may be a value based on the minimum amplitude or the maximum amplitude of the reproduction signal obtained by reproducing the space portion. A value based on the minimum amplitude (for example, an average value or a median value) is used for the low-to-high type optical disc, and a value based on the maximum amplitude is used for the high-to-low type optical disc. This is because it depends on the reflectance corresponding to “space”.

  Further, the setting value calculating step described above may include a step of multiplying the upper limit value of the recording power at the time of forming the space by a predetermined coefficient. The predetermined coefficient may be a predetermined value less than 1. In this way, if a sufficient margin is provided for the upper limit value, a problem is less likely to occur.

  Furthermore, the optimization step described above may be performed by fixing the setting value of the recording power at the time of forming the space and setting the recording power at the time of forming the mark to a different value and performing test recording respectively. . For example, the recording power Pw at the time of mark formation may be optimized according to conventional OPC technology.

  Further, the upper limit calculation step described above includes a step of calculating a rate of change of the amplitude of the specific code for each recording power at the time of forming a space, and a time of forming a space where the rate of change of the amplitude of the specific code satisfies a predetermined condition. And a step of specifying the recording power as an upper limit value. According to the novel knowledge of the inventor of the present invention, it has been found that when the recording power Ps at the time of forming a space exceeds the upper limit value, the rate of change in amplitude greatly increases, resulting in degradation of recording quality. This is to detect a point.

  The optical disc recording / reproducing apparatus according to the present invention also includes a recording means for writing to the optical disc for each of a plurality of recording powers at the time of forming a space, and a specification in a reproduction signal obtained by reproducing a result of writing by the recording means A measurement step for measuring the amplitude of the code, and an upper limit value setting means for calculating an upper limit value of the recording power at the time of space formation using the measured amplitude of the specific code.

  Furthermore, if an optical disc recording / reproducing apparatus having a memory storing the upper limit value of the recording power at the time of forming a space is used, it becomes easy to adjust the recording power at the time of forming the space with respect to the optical disc to be written. Similarly, if an optical disc in which the upper limit value of the recording power at the time of forming the space is recorded, it becomes easy to adjust the recording power at the time of forming the space with respect to the optical disc recording / reproducing apparatus.

  A program for causing a processor to execute the recording condition determining method of the present invention can be created, and the program is a storage medium such as a flexible disk, an optical disk such as a CD-ROM, a magneto-optical disk, a semiconductor memory, and a hard disk. Alternatively, it is stored in a nonvolatile memory of a storage device or a processor. In some cases, digital signals are distributed over a network. Note that data being processed is temporarily stored in a storage device such as a processor memory.

  According to the present invention, it is possible to determine the recording power Ps when forming an appropriate space.

  In addition, according to another aspect of the present invention, it is possible to improve the recording quality with respect to the optical disc by using the recording power Ps at the time of forming an appropriate space.

  A functional block diagram of the drive system in the embodiment of the present invention will be described with reference to FIG. The drive system according to the embodiment of the present invention includes an optical information recording / reproducing apparatus 100, and an input / output system (not shown) including a display unit such as a television receiver and an operation unit such as a remote controller.

  The optical information recording / reproducing apparatus 100 includes a memory 127 that stores data in the middle of processing, data of processing results, reference data in processing, and the like, and a memory circuit 126 in which a program for performing processing described below is recorded. A control circuit 125 including a CPU (Central Processing Unit), an interface unit (I / F) 128 that is an interface with an input / output system, and a maximum amplitude level or minimum of an RF signal that is a reproduction signal A characteristic value detection unit 124 that detects an amplitude level and the like, and a 2T to 8T code (for example, in the case of the Blu-ray standard. In the case of the Blu-ray standard, the synchronous code 9T is also identified from the HD signal. -In the case of the DVD standard, which of 2T to 11T code and 13T of the synchronization code is identified) The data demodulating circuit 123 that performs processing for decoding, the pickup unit 110, and the data to be recorded output from the control circuit 125 are subjected to predetermined modulation and output to the laser diode (LD) driver 121. A data modulation circuit 129, an LD driver 121, a rotation control unit and a motor of the optical disc 150, a servo control unit (not shown) for the pickup unit 110, and the like are included.

  The pickup unit 110 includes an objective lens 114, a beam splitter 116, a detection lens 115, a collimator lens 113, an LD 111, and a photodetector (PD) 112. In the pickup unit 110, an actuator (not shown) operates in accordance with control of a servo control unit (not shown), and focusing and tracking are performed.

  The control circuit 125 is connected to the memory 127, the characteristic value detection unit 124, the I / F 128, the LD driver 121, the data modulation circuit 129, a rotation control unit and a servo control unit (not shown), and the like. In addition, the characteristic value detection unit 124 is connected to the PD 112, the control circuit 125, and the like. The LD driver 121 is connected to the data modulation circuit 129, the control circuit 125, and the LD 111. The control circuit 125 is also connected to the input / output system via the I / F 128.

  Next, an outline of processing when data is recorded on the optical disc 150 will be described. First, the control circuit 125 causes the data modulation circuit 129 to perform a predetermined modulation process on the data to be recorded on the optical disc 150, and the data modulation circuit 129 outputs the data after the modulation process to the LD driver 121. The LD driver 121 drives the LD 111 with the received data according to specified recording conditions to output laser light. The laser light is irradiated onto the disk 150 through the collimating lens 113, the beam splitter 116, and the objective lens 114, thereby forming marks and spaces on the optical disk 150.

  An outline of processing when data recorded on the optical disc 150 is reproduced will be described. In accordance with an instruction from the control circuit 125, the LD driver 121 drives the LD 111 to output laser light. The laser light is irradiated onto the optical disc 150 through the collimating lens 113, the beam splitter 116, and the objective lens 114. The reflected light from the optical disk 150 is input to the PD 112 via the objective lens 114, the beam splitter 116, and the detection lens 115. The PD 112 converts the reflected light from the disk 150 into an electrical signal and outputs it to the characteristic value detection unit 124 and the like. The data demodulation circuit 123 or the like performs a predetermined decoding process on the output reproduction signal, and outputs the decoded data to the display unit of the input / output system via the control circuit 125 and the I / F 128 for reproduction. Display data. Since the characteristic value detection unit 124 is not used in normal reproduction, its operation will be described below.

  In the following, description will be made on the premise of a recording pulse shape used in a system according to the Blu-ray standard. FIG. 2A shows various recording parameters when the multi-pulse is adopted. The recording power parameters include Pc in addition to the recording power Pw at the time of mark formation and the recording power Ps at the time of space formation. And Pbw. Also, parameters related to timing include dTtop, Ttop, Tmp, Tlp, and dTs. FIG. 2B shows various recording parameters when the non-multi pulse is employed. In this case, the recording power parameters include the recording power Pw at the time of mark formation and the recording power at the time of space formation. The recording power Ps is included, and other parameters include Pm and Pc. Further, parameters related to timing include dTtop, LDH, Duty, TBST, dTlast, dTs, and the like. As described above, whether the multi-pulse or the non-multi-pulse is employed, it is necessary to appropriately set the recording power Pw at the time of mark formation and the recording power Ps at the time of space formation. Although not shown, even in other standards, the recording power Pw at the time of mark formation and the recording power Ps at the time of space formation are important parameters.

  Next, a process for setting the recording power Ps at the time of forming a space and the recording power Pw at the time of forming a mark will be described with reference to FIGS. First, the control circuit 125 sets basic conditions such as position information and recording speed for test recording in the servo control unit and the like (step S1). Note that the LD driver 121 is set to predetermined initial values for various recording parameters other than the recording power Ps at the time of space formation. Then, the control circuit 125 performs Ps optimization processing (step S3). This Ps optimization process will be described with reference to FIGS.

  The control circuit 125 sets the initial value of Ps in the LD driver 121 (step S11). In the following, an example of increasing the value of Ps is shown, but the value of Ps may be decreased. Then, the counter n is initialized to 1 (step S13). Thereafter, the control circuit 125 causes the LD driver 121 and the like to perform data recording of predetermined data in the test recording area under the set conditions (step S15). Then, the control circuit 125 causes the pickup unit 110 and the like to reproduce the recording result of the data recording performed in step S15, and at that time, the characteristic value detection unit 124 reproduces the space portion. The minimum level of the amplitude of the obtained signal is measured and output to the control circuit 125 (step S17).

  Here, it is premised on a recordable optical disc (Low-to-high type (the reflected light level is increased by forming a mark)) conforming to the Blu-ray standard. Specifically, in the case of such an optical disc, data codes to be recorded are 2T to 8T (the data reference clock period is 1T), and FIG. 5 (the vertical axis represents voltage and the horizontal axis represents time). ), The largest 8T mark is the maximum level (I8H), and the 8T space is the minimum level (I8L). Actually, code data of 4T (or 5T) or more is the maximum level from the relationship between the code length and the spot effective diameter of the irradiation laser. As described above, the characteristic value detection unit 124 measures the voltage level (I8L) at which the signal amplitude obtained when the space portion is reproduced is minimized.

  In the case of a high-to-low type recordable optical disc, the signal level positional relationship between the mark portion and the space portion is reversed. In this case, the characteristic value detection unit 124 is obtained when the space portion is reproduced. The voltage level (I8H) that maximizes the signal amplitude is measured.

  Next, the control circuit 125 determines whether n = 1 (step S19). If n = 1, n is incremented by 1 (step S21), Ps is increased by a predetermined amount (for example, 0.1 mW) and set in the LD driver 121 or the like (step S23). Then, the process returns to step S15. That is, the amplitude level is measured by changing the value of Ps at least once.

  If n is 2 or more, the control circuit 125 calculates the change rate of the amplitude level (step S25). That is, the rate of change is calculated by the difference in amplitude level (= current amplitude level−previous amplitude level) / Ps increase amount (for example, 0.1 mW). Note that the reflectance level may be measured to calculate the rate of change of the reflectance level.

  Then, the control circuit 125 determines whether the change rate of the amplitude level is greater than or equal to a predetermined threshold (step S27). The predetermined threshold is stored in advance in the memory 127, for example. If the rate of change is less than the predetermined threshold, the process proceeds to step S21. The reason why such a process is performed is that the relationship between Ps and the measured amplitude level is as shown in FIG. 6, for example. In FIG. 6, the vertical axis represents the amplitude level of I8L, and the horizontal axis represents Ps (mW). As described above, when Ps is increased, the rate of change is significantly increased with a certain value (1.3 mW in the example of FIG. 6) as a boundary. In the example of FIG. 6, if it is less than 1.3 mW, the rate of change does not become a large positive value even if it goes up and down, but if it becomes 1.3 mW or more, the rate of change becomes a large positive value. If such a change in change rate cannot be detected, the process returns to step S21. If the rate of change is less than a predetermined threshold value, it may not be appropriate to perform Steps S21 to S27 indefinitely. Therefore, for example, a limit is set on the number of repetitions, or the recording power Ps at the time of forming a space is set. A range is provided, and Ps is changed within the range. When Ps is decreased, it can be determined that the upper limit has been reached if the rate of change in amplitude level is less than the threshold.

  On the other hand, when such a change in the change rate is detected, that is, when it is determined that the change rate is equal to or greater than a predetermined threshold, the control circuit 125 specifies the previous Ps value as the upper limit value. For example, it is stored in the memory 127 (step S29). Then, the control circuit 127 calculates the optimum value of Ps by multiplying the upper limit value of Ps specified in step S29 by a predetermined coefficient, and sets it in the LD driver 121 or the like (step S31). The predetermined coefficient is, for example, a value less than 1 such as 0.9, and is determined in advance by an experiment or the like so as to obtain a sufficient margin from the upper limit value. However, 1 may be set depending on circumstances. The predetermined coefficient is stored in advance in the memory 127, for example. Note that the optimum value of Ps calculated in step S31 is set as a more preferable value rather than an absolute optimum value. Moreover, although the example which multiplied the predetermined coefficient was shown above, the calculation which reduces a predetermined coefficient depending on the case may be implemented. Then, the process returns to the original process.

  In addition, since the data length of the I8L described above is obtained from a space portion that is sufficiently long with respect to the effective spot diameter of the laser to be irradiated, it is not affected by the performance of adjacent marks. . Therefore, when the laser beam is irradiated with Ps larger than the upper limit value, it is considered that the space portion becomes like the mark portion due to the amount of heat stored in the space portion by the recording power Ps at the time of forming the space. .

  For example, FIG. 7 shows the DCJ (Data Clock Jitter) measurement results when recording is performed while changing the main recording power Pw under different Ps conditions (1.1 mW, 1.3 mW and 1.5 mW). In FIG. 7, the vertical axis represents DCJ [%], and the horizontal axis represents Pw [mW]. In FIG. 7, when the case of 1.3 mW which is the Ps upper limit value is compared with the case of 1.5 mW exceeding the Ps upper limit value, the DCJ is clearly increased in the case of 1.5 mW. The width of Pw that becomes less than 8% also decreases. As described above, since the recording quality is deteriorated and the power margin is also decreased, it is understood that Ps exceeding the upper limit is not preferable. Further, when the case of 1.3 mW which is the upper limit of Ps is compared with the case of 1.1 mW, the minimum value of DCJ is better when it is 1.3 mW. For example, the width of Pw where DCJ is less than 8% Is better at 1.1 mW. It can be seen that 1.1 mW is more resistant to fluctuations in Pw.

  Since the recording characteristics change in accordance with Ps in this way, for example, as described above, by calculating an appropriate coefficient for obtaining a sufficient margin experimentally and multiplying the upper limit value, The optimum value shall be obtained.

  Such a change in recording characteristics according to Ps may be attributed to the fact that Ps also plays a role of bias control for determining a heat storage state immediately before mark formation by the main recording power Pw. Therefore, if an appropriate coefficient is calculated as described above, an appropriate recording characteristic can be obtained.

  Further, since Ps varies depending on the characteristics of the optical disk such as the film thickness, the laser spot effective diameter, the hardware characteristics such as the LD driver, the recording speed, the temperature, and the like, it is preferably performed every time the optical disk is replaced.

  Returning to the explanation of FIG. 3, when the Ps optimization process is completed, the control circuit 125 performs the optimization process of the recording power Pw at the time of mark formation (step S5). In this step, OPC that has been conventionally performed may be performed. That is, Ps is fixed to the optimum value, data recording is performed on the test recording area with a different main recording power Pw, a reproduction signal is obtained by reproducing the data recording, and a predetermined signal is obtained from the reproduction signal. An evaluation index is calculated. By executing such processing by changing the main recording power Pw, the main recording power Pw that can obtain the best evaluation index is specified as the optimum value. Then, the main recording power Pw is set in the LD driver 121 or the like. The evaluation index is, for example, β, asymmetry value, modulation degree, jitter, error, and the like.

  Thereafter, the control circuit 125 causes the user data to be recorded as usual (step S7).

  By performing the processing as described above, the recording quality can be improved and appropriate recording can be performed on the recordable optical disk.

  In some cases, the upper limit value of Ps may be stored in the memory 127 of the optical information recording / reproducing apparatus 100.

  Further, the upper limit value of Ps, the coefficient for calculating the optimum Ps, or both may be recorded on the optical disc 150. When it is held on the optical disc 150, it is held in the Lead-in area as shown in FIG. The lead-in area is largely divided into a system lead-in area, a connection area, and a data lead-in area. The system lead-in area includes an initial zone, a buffer zone, a control data zone, and a buffer. -Includes zones. The connection area includes a connection zone. Further, the data lead-in area includes a guard track zone, a disc test zone, a drive test zone, a guard track zone, an RMD duplication zone, a recording management zone, an R-physical format information zone, and a reference code. -Includes zones. In the present embodiment, the recording condition data zone 170 is included in the control data zone of the system lead-in area.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this. For example, the functional block diagram of FIG. 1 is shown for explaining the embodiment, and may not always match an actual circuit or module configuration. In addition, as for the processing flow, as long as the processing result is the same, the processing order may be changed, or the processing order may be executed in parallel. For example, in FIG. 4, after data recording is performed for all Ps, data reproduction and measurement may be performed together, and then the change rate may be calculated together.

It is a functional block diagram concerning an embodiment of the invention. (A) represents various recording parameters in the case of multi-pulse, and (b) is a diagram representing various recording parameters in the case of non-multi-pulse. It is a figure which shows the main processing flow in embodiment of this invention. It is a figure which shows the processing flow of Ps optimization process. It is a figure for demonstrating the amplitude level which should be measured. It is a figure showing the relationship between Ps and I8L. It is a figure showing the relationship between Pw and DCJ in the case of varying Ps. It is a figure which shows the data structure stored in an optical disk.

Explanation of symbols

100 Optical Information Recording / Reproducing Device 110 Pickup Unit 111 LD
112 PD 113 Collimating lens 114 Objective lens 115 Detection lens 116 Beam splitter 121 LD driver 123 Data demodulation circuit 124 Characteristic value detection unit 125 Control circuit 126 Memory circuit 127 Memory 128 I / F 129 Data modulation circuit 150 Optical disk

Claims (10)

A recording step of writing to the test recording area of the write-once optical disc for each of the plurality of recording power at the time of space formation,
The recording have you in a reproduction signal obtained by reproducing the result of the writing in the step, a measuring step of measuring the amplitude of the specific code is a space or 5T,
Calculating a rate of change in amplitude of the specific code for each of the plurality of recording powers;
The change rate with respect to each of the plurality of recording powers is compared with a predetermined threshold value, and the maximum recording power among the recording powers with the change rate being less than the predetermined threshold value is set as the upper limit value of the recording power at the time of forming the space. Identifying steps;
A set value calculating step for calculating a set value of the recording power at the time of forming the space based on an upper limit value of the recording power at the time of forming the space;
An optimization step of performing a recording power optimization process at the time of mark formation after setting a set value of the recording power at the time of forming the space;
A recording condition determination method for a write-once optical disc . The set value calculating step includes:
Recording condition determining method of the write-once optical disc according to claim 1, including the step of multiplying a predetermined coefficient to the upper limit value of the recording power at the time of the space formed. The recording condition determination method for a write-once optical disc according to claim 2 , wherein the predetermined coefficient is a predetermined value less than one . Said optimization step comprises:
Fixing the set value of the recording power at the time of the space formation, the recording condition of the write-once optical disk according to claim 1, carried out by performing the respective test recording by setting the recording power at the time of the mark formed at different values Decision method. And recording means for writing to the test recording area of the write-once optical disc for each of the plurality of recording power at the time of space formation,
And have you in a reproduction signal obtained by reproducing the result of writing by the recording means, measuring means for measuring the amplitude of the specific code is a space or 5T,
Means for calculating a rate of change in amplitude of the specific code for each of the plurality of recording powers;
The change rate with respect to each of the plurality of recording powers is compared with a predetermined threshold value, and the maximum recording power among the recording powers with the change rate being less than the predetermined threshold value is set as the upper limit value of the recording power at the time of forming the space. Means to identify;
Based on the upper limit value of the recording power at the time of forming the space, a set value calculation means for calculating a setting value of the recording power at the time of forming the space;
After setting the setting value of the recording power at the time of forming the space, an optimization means for performing a recording power optimization process at the time of mark formation;
An optical disc recording / reproducing apparatus having: 6. The optical disc recording / reproducing apparatus according to claim 5 , wherein the set value calculating means multiplies a predetermined coefficient by an upper limit value of the recording power at the time of forming the space. The optical disc recording / reproducing apparatus according to claim 6 , wherein the predetermined coefficient is a predetermined value less than one. The optimization means comprises:
6. The optical disc recording / reproducing apparatus according to claim 5 , wherein test recording is performed by fixing a set value of the recording power at the time of forming the space and setting the recording power at the time of forming the mark to a different value. A recording step of writing to the test recording area of the write-once optical disc for each of the plurality of recording power at the time of space formation,
The recording have you in a reproduction signal obtained by reproducing the result of the writing in the step, a measuring step of measuring the amplitude of the specific code is a space or 5T,
Calculating a rate of change in amplitude of the specific code for each of the plurality of recording powers;
The change rate with respect to each of the plurality of recording powers is compared with a predetermined threshold value, and the maximum recording power among the recording powers with the change rate being less than the predetermined threshold value is set as the upper limit value of the recording power at the time of forming the space. Identifying steps;
A set value calculating step for calculating a set value of the recording power at the time of forming the space based on an upper limit value of the recording power at the time of forming the space;
An optimization step of performing a recording power optimization process at the time of mark formation after setting a set value of the recording power at the time of forming the space;
A program that causes a processor to execute. A processor storing the program according to claim 9 in a memory.

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