JP4553883B2 - Optical disc recording apparatus, optical disc recording method and program - Google Patents

Description

  The present invention relates to a technique for optimizing recording power for an optical disc (also called an optical information recording medium).

  For example, Japanese Patent Laid-Open No. 5-144000 discloses an optical information recording apparatus capable of correcting the intensity of laser light in accordance with the pit formation state during information recording. Specifically, information is recorded by changing the intensity of the laser beam corresponding to the reference digital signal A by the laser driving circuit, and the reflected light from the optical disk during recording is received by the photodetector, and the light is recorded. A signal B having a voltage proportional to the intensity is output. The signal B is amplified by the RF amplifier by the pulse signal C corresponding to the rear end of the pit portion and the pulse signal D corresponding to the center portion of the non-pit portion, which are generated from the timing pulse generation circuit based on the reference digital signal. The voltage of the signal B ′ obtained in this way is held in the sample-hold circuit, and the current applied to the laser diode is controlled so that the difference between these voltages always matches the reference value. In the technique described in this publication, the recording power is adjusted during data recording, but the data in the recording power optimization process using the test writing area is not used.

Japanese Patent Laid-Open No. 2001-351242 always provides an appropriate recording state in response to a change in the situation such as a change in the recording layer or a change in the wavelength of the laser beam when recording on one optical disk. Techniques for doing so are disclosed. Specifically, asymmetry, which is a parameter for evaluating the quality of the recording signal, varies depending on the recording depth of the pit. On the other hand, the recording depth of the pits corresponds to the ratio HL / HS between the peak value HS of the reflected light power at the beginning of the irradiation of the recording laser beam and the stable value HL thereafter. HL / HS varies depending on the recording power. Therefore, HS and HL are detected at the time of recording on the optical disc, and a recording power command value is output from the comparison means so that it matches the value set by the ratio setting means based on the trial writing, and the optical power is set in the optical head via the ALPC circuit. Controls the output power of the laser diode. In the technology described in this publication, asymmetry is mentioned, but HL / HS alone cannot appropriately cope with asymmetry fluctuations.
JP-A-5-144000 JP 2001-351242 A

  In the prior art described above, since only the signal amplitude of the pit formation portion or space formation portion of the WRF signal is detected, only the modulation (or β which is a well-known evaluation index) level at the time of recording can be detected. Since the detected modulation (or β) varies depending on the disc (also referred to as media), recording speed, and recording pulse setting, a correction coefficient is required for each recording condition, or CAV (the recording speed fluctuates within the disc surface). There is a problem that it is not suitable for recording.

  In addition, since discs of standards such as BD (Blu-ray Disc) and HD (High Definition) -DVD perform PRML (Partial Response Maximum Likelihood) processing, variations in asymmetry affect recording characteristics. However, there is a problem that asymmetry variation cannot be corrected by modulation (or β) detection as in the prior art.

  Accordingly, an object of the present invention is to provide a novel technique for enabling adaptive control of recording power so that asymmetry is constant within a disk surface.

  Another object of the present invention is to provide a novel technique for enabling adaptive control of recording power so that asymmetry is constant in the disk surface even when CAV is employed.

  The optical disc recording apparatus according to the first aspect of the present invention is configured to record the predetermined pattern on the disc with a plurality of recording powers in order to specify the optimum recording power corresponding to the optimum asymmetry value. The detection means for detecting the value of the received light signal corresponding to the intensity of the reflected light from the disc at the timing specified based on the recording power and the value of the received light signal detected by the detection means for each recording power Based on the index value calculated by the index value calculating means while the data is recorded on the disc with the recording power that is the optimum recording power, and the index value calculating means for calculating the index value of the evaluation index Power correction means for correcting the recording power. The detection means corresponds to the intensity of the reflected light from the disc at a timing specified from the recording pattern in the data recording while performing data recording on the disc with the optimum recording power. The value of the received light signal is detected. The index value calculation means calculates the index value of a specific evaluation index as the current index value from the value of the received light signal during data recording at the recording power that is the optimum recording power. Further, the power correction means corrects the recording power according to the current index value with reference to the optimal index value that is the evaluation value of the specific evaluation index corresponding to the optimal recording power.

  In order to detect the value of the received light signal at the timing specified based on the predetermined pattern and the timing specified from the recording pattern in data recording, it is necessary to keep the asymmetry constant from the formation pattern of pits and spaces. The recording power control can be performed by detecting the value of the received light signal at a certain point and calculating the index value of the specific index. In addition, since adaptive recording power control is performed during data recording based on the index value of a specific index calculated at the time of trial writing, the CAV is the inner circumference or the outer circumference of the disc. But it will be easy to deal with.

  For example, the timing may include a first portion that is a portion after recording the shortest pit and a second portion that is a portion after recording a pit having a length such that the RF signal is saturated. is there. For example, in writing to a BD or HD-DVD disc, the longer the laser irradiation time at the time of pit formation, the larger the amount of fluctuation of the received light signal corresponding to the reflected light intensity at the end of laser irradiation. Since the fluctuation amount greatly affects the asymmetry, attention is paid to the above points (that is, portions).

  In such a case, the specific evaluation index described above represents the degree of level deviation in the first portion from the middle between the steady level at the time of space formation and the level in the second portion. In some cases. This is because such a degree of bias is highly correlated with asymmetry.

  Furthermore, the first aspect of the present invention may further include means for extracting a relationship between the recording power and the index value (for example, a linear coefficient if linear approximation is possible) based on the index value for each recording power. Good. At this time, the power correcting means may determine the corrected recording power based on the relationship between the recording power and the index value and the deviation of the current index value from the optimum index value. In this way, the recording power can be corrected by an appropriate amount.

  The first aspect of the present invention may further include means for specifying the optimum index value from the optimum recording power corresponding to the optimum asymmetry value. The optimum index value may be specified from the optimum recording power by a specific evaluation index, or may be a certain fixed value.

  Furthermore, the specific evaluation index may be an evaluation index that is most susceptible to the influence of recording power among a plurality of evaluation indexes. This is because if the sensitivity to the recording power is high, the adjustment is easy.

  In addition, the timing described above includes a first portion that is a portion after the shortest pit is recorded, a second portion that is a portion after the shortest pit is recorded, and an RF signal. And a third portion which is a portion after recording a pit having such a length that saturates. Such points are identified from the relationship with asymmetry.

  Then, the specific evaluation index described above includes the first index representing the degree of level deviation in the first portion from the middle between the steady level at the time of space formation and the level in the third portion, and the space formation A second index indicating the degree of level deviation in the second part from the middle of the steady level of the time and the level in the third part, and the ratio of the level in the first part and the level in the second part. In some cases, the third index is the index most susceptible to the influence of the recording power.

  Further, the specific evaluation index described above includes a first index representing a degree of level deviation in the first portion from a middle level between a steady level at the time of space formation and a level in the third portion, and space formation. A second index indicating the degree of level deviation in the second part from the middle of the steady level of the time and the level in the third part, and the ratio of the level in the first part and the level in the second part. In some cases, the third index is an integrated index.

  Various modifications are possible for the specific evaluation index, but the above three indices are useful from the relationship with asymmetry.

  In addition, the specific evaluation index described above may be an evaluation index related to a value obtained by summing magnitudes of deviations from respective target values of a plurality of predetermined evaluation indexes. In this way, the recording power is corrected so that the plurality of evaluation indices are close to the target, and as a result, the asymmetry value can be made close to the optimum.

  Furthermore, data relating to an allowable range for the optimum evaluation value of a specific evaluation index may be stored in a disk or a memory of a recording device. In this case, the power correction unit may perform power correction when the current evaluation value falls outside the allowable range. This is because frequent correction of the recording power may not be preferable.

  In the optical disk recording method according to the second aspect of the present invention, a predetermined pattern is recorded while a predetermined pattern is recorded on a disk with a plurality of recording powers in order to identify an optimal recording power corresponding to an optimal asymmetry value. From the detection step of detecting the value of the received light signal corresponding to the intensity of the reflected light from the disc at the timing specified based on each recording power, and from the value of the received light signal detected in the detecting step for each recording power, An index value calculation step for calculating an index value of a specific evaluation index and a timing specified from a recording pattern in data recording while data is being recorded on the disc with an optimum recording power. The step of detecting the value of the received light signal corresponding to the intensity of the reflected light from the disk and the recording power that is optimal The step of calculating the index value of a specific evaluation index as the current index value from the value of the received light signal during data recording with power, and data recording on the disc with the recording power that is the optimum recording power In the meantime, the power that corrects the recording power based on the index value calculated in the index value calculation step using the optimal index value that is the evaluation value of the specific evaluation index corresponding to the optimal recording power and the current index value A correction step.

  In addition, the program for the optical disc recording apparatus according to the third aspect of the present invention records a predetermined pattern on a disc with a plurality of recording powers in order to specify the optimum recording power corresponding to the optimum asymmetry value. In addition, when the value of the received light signal corresponding to the intensity of the reflected light from the disc is detected for each recording power at the timing specified based on the predetermined pattern, the detected light reception signal value for each of the recording powers An index value calculating step for calculating an index value of a specific evaluation index, and a timing specified from a recording pattern in data recording while data is being recorded on the disc with an optimum recording power When detecting the value of the received light signal corresponding to the intensity of the reflected light from the disc, the recording power at the optimum recording power The step of calculating the index value of a specific evaluation index as the current index value from the value of the received light signal during data recording, and while recording data on the disc with the recording power that is the optimum recording power A power correction step for correcting the recording power based on the index value calculated in the index value calculation step using the optimal index value that is the evaluation value of the specific evaluation index corresponding to the optimal recording power and the current index value And let the processor execute

  The program is stored in a central processing unit having a storage medium or storage device such as a flexible disk, an optical disk such as a CD-ROM, a magneto-optical disk, a semiconductor memory, or a hard disk, and a memory. Moreover, it may be distributed as a digital signal via a network or the like. Note that intermediate processing results are temporarily stored in a work memory area of various apparatuses.

  According to the present invention, it is possible to adaptively control the recording power so that the asymmetry is constant within the disk surface.

  Further, according to another aspect of the present invention, even when CAV is employed, adaptive control of recording power is possible so that asymmetry is constant within the disk surface.

  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 disc recording / reproducing apparatus 100, and an input / output system 130 including a display unit 131 such as a television receiver and an operation unit 132 such as a remote controller.

  The optical disc recording / reproducing apparatus 100 has a memory 127 for storing data in the middle of processing, data of processing results, reference data in processing (for example, strategy data corresponding to each media ID), and processing described below. A CPU (Central Processing Unit) 125 including a memory circuit 1254 in which a program is recorded, an interface unit (I / F) 128 that is an interface with the input / output system 130, an RF signal and a WRF that are reproduction signals. A characteristic value detection unit 124 that detects a value of a predetermined timing of the signal, a slicer 122 that performs processing for decoding, for example, which of 2T to 11T codes has been read from an RF signal that is a reproduction signal, and data demodulation Circuit 123, pickup unit 110, laser diode (L ) And the driver 121 includes a rotation control unit and servo control unit or the like of the motor and the pickup unit 110 of the disc 150 (not shown).

  The pickup unit 110 includes an objective lens 114, a beam splitter 116, a detection lens 115, a collimator lens 113, a laser diode (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 CPU 125 is connected to a memory 127, a characteristic value detection unit 124, an I / F 128, an LD driver 121, a rotation control unit and a servo control unit (not shown), and the like. The CPU 125 functions as a detection value calculation unit 1251, an optimization determination unit 1252, and a power control unit 1253 by executing a program stored in the memory circuit 1254. Furthermore, the characteristic value detection unit 124 is connected to the PD 112, the CPU 125, and the like. The LD driver 121 is connected to the CPU 125 and the LD 111. The CPU 125 is also connected to the input / output system 130 via the I / F 128.

  Next, an outline of processing when data is recorded on the disk 150 will be described. First, the CPU 125 or a data modulation circuit (not shown) provided separately performs a modulation process on the data to be written on the disk 150 and 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 beam is irradiated onto the disk 150 through the collimating lens 113, the beam splitter 116, and the objective lens 114 to form a space and a pit on the disk 150.

  An outline of processing when data recorded on the disk 150 is reproduced will be described. In accordance with an instruction from the CPU 125, the LD driver 121 drives the LD 111 to output laser light. The laser beam is applied to the disk 150 through the collimating lens 113, the beam splitter 116, and the objective lens 114. The reflected light from the 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, the slicer 122, and the like. The slicer 122, the data demodulation circuit 123, and the like perform predetermined decoding processing on the output reproduction signal, and output the decoded data to the display unit 131 of the input / output system 130 via the CPU 125 and the I / F 128. Display the playback data. The characteristic value detection unit 124 is not used in normal reproduction.

[Embodiment 1]
Next, the operation of the optical disc recording / reproducing apparatus 100 according to the first embodiment will be described with reference to FIGS. First, the optical disc recording / reproducing apparatus 100 accepts insertion of the disc 150 by the user (step S1). Then, the CPU 125 reads the media ID data written in the predetermined area via the PD 112, the slicer 122, and the data demodulation circuit 123 (step S3), and the CPU 125 corresponds to the media ID in the memory 127, for example. The stored strategy data is read out (step S5). When data related to the allowable range of the symmetry shift value, which is an evaluation index described below, is recorded on the disk 150, the data related to the allowable range is also read out.

  Further, the CPU 125 causes writing to be performed so as to form a predetermined pit and space pattern in the trial writing area of the disk 150 in accordance with the read strategy data. In order to specify the optimum recording power, different recording powers are set in the LD driver 121 for a predetermined pit and space pattern and are written a predetermined number of times. At the same time, the PD 112 detects reflected light from the disk 150 while writing with each recording power and outputs a corresponding WRF signal to the characteristic value detection unit 124. The characteristic value detection unit 124 detects a value necessary for calculating a symmetry shift value that is an evaluation index at the timing shown in FIG.

  FIG. 3 shows (a) a pulse output waveform of a laser beam output from the LD 111 when forming 8T, 4T, 2T, and 7T pits, (b) a sampling signal for instructing sampling timing, and (c) recording. An example of the WRF signal that is a result of detecting the reflected light of PD by the PD 112 and (d) pits and spaces to be formed is shown.

  The symmetry shift value, which is an evaluation index in the present embodiment, is a steady level wL8T (voltage value; the same applies hereinafter) at the time of forming a space, and a level wP8T immediately after recording a pit having a length such that the RF signal is saturated. Represents the degree of bias of the level wP8T immediately after the shortest pit is written. More specifically, the symmetry shift value γ = {(wL8T + wP8T) / 2−wP2T} / (wL8T−wP8T). That is, it is normalized by (wL8T-wP8T). This evaluation index is known to have a high correlation with the asymmetry value.

  In the case of BD and HD-DVD, the pit length at which the RF signal is saturated is 6T or more. In the example of FIG. 3, 8T and 7T are pit lengths at which the RF signal is saturated. The shortest pit is a 2T pit in the case of BD or HD-DVD. Accordingly, as shown in FIG. 3B, the sampling signal is turned on immediately after the LD output signal for forming the 8T pit, immediately after the LD output signal for forming the 2T pit, and immediately after the LD output signal for forming 7T. The sampling signal is generated by the CPU 125 itself or a circuit that operates in response to an instruction from the CPU 125. In the WRF signal, as shown in FIG. 3 (c), a spike appears immediately after the LD output signal for pit formation. The depth of the groove of the spike varies depending on the pit length to be formed. Then, the level immediately after the LD output signal for 2T pit formation (timing A) is specified as wP2T, and the level immediately after the LD output signal for 6T or more pit formation (timing B and C) is specified as wP8T. . Further, since the steady level wL8T at the time of forming the space is necessary, in order to detect the steady level wL8T at the time of forming the space after a predetermined timing when the steady state is reached, that is, Δt after the LD output signal becomes the space forming level. The sampling signal is turned on (timing D and E) for detection.

  wP2T, wP8T, and wL8T are also detected several times at a specific recording power. However, since the values may change, the average value may be calculated and the symmetry shift value may be calculated using the average value. .

  Note that, as shown in FIG. 3D, the pits are formed in a form slightly deviated from the LD output signal.

  In this way, the characteristic value detection unit 124 detects wP2T, wP8T, and wL8T for each recording power.

  The detection value calculation unit 1251 of the CPU 125 receives the values of wP2T, wP8T, and wL8T from the characteristic value detection unit 124, calculates the symmetry shift value γ for each recording power, and stores it in the memory 127, for example (step S7).

  When the writing to the trial writing area is completed, the CPU 125 performs a process of setting the reproduction power in the LD driver 121 in order to reproduce the result of the trial writing. The PD 112 detects the reflected light from the disk 150 and outputs an RF signal to the characteristic value detection unit 124. The characteristic value detection unit 124 detects a value necessary for calculating the asymmetry value and outputs it to the CPU 125. The detection value calculation unit 1251 of the CPU 125 calculates an asymmetry value for each recording power from the detection value from the characteristic value detection unit 124 and stores it in the memory 127, for example (step S9).

  Although the asymmetry value is well known, the values of I14L, I3L, I3H, and I14H are detected in an RF signal as shown in FIG. )}.

  Next, the optimization determining unit 1252 identifies the recording power at which the asymmetry value is optimal (step S11). The corresponding recording power is specified by setting the asymmetry value closest to the predetermined optimum asymmetry value as the optimum. Similarly, the symmetry shift value γ corresponding to the optimum recording power is also specified.

  Further, the power control unit 1253 performs a regression calculation from the symmetry shift value stored in the memory 127 and the corresponding recording power value, calculates a proportional coefficient of the symmetry shift value-recording power, and stores it in the memory 127. (Step S13). As shown in FIG. 5, the relationship between the recording power and the symmetry shift value is approximated by a straight line a to calculate a proportionality coefficient α of the equation γ = αx + β (x: recording power) of the straight line a. In FIG. 5, the optimum power x ′ and the symmetry shift value γ ′ are also specified in step S11.

  Thereafter, the power control unit 1253 of the CPU 125 sets the optimum recording power in the LD driver 121 and performs data recording (step S15). Processing in this data recording will be described with reference to FIGS.

  First, while the data recording is performed with the recording power set to the optimum recording power as usual, the current symmetry shift value γ is calculated as in step S7 (step S21). Since the CPU 125 knows what pits and spaces are formed, the sampling signal can be output at an appropriate timing. For example, the symmetric deviation value γ is calculated by averaging values sampled several times for each predetermined period. It may be calculated every time data sufficient to calculate the symmetry shift value γ is acquired.

Then, the optimization judgment unit 1252, the current Shinmetorizure value γ is, the optimum Shinmetorizure values identified in the data and step S 11 related to tolerance of prerecorded and Shinmetorizure value, for example, a disk 150 or memory 127 It is judged whether it is in the allowable range specified from (step S23). For example, the data regarding the allowable range of the symmetry shift value may be data indicating a ratio of plus / minus x% from the optimum symmetry shift value or data indicating a value of plus / minus y.

  For example, assuming that FIG. 7A shows a state in which the optimum symmetry shift value is calculated, for example, if underpower is generated during data recording, the state shown in FIG. 7B is obtained. That is, the value of wP2T rises above the middle between wL8T and wP8T. On the other hand, if the overpower is generated during data recording, the state shown in FIG. In other words, the state is such that the value of wP2T falls below the middle of wL8T and wP8T. In either case, adjustment is required if it affects the asymmetry value and fluctuates over a predetermined range.

If it is determined that the current symmetry shift value γ is within the allowable range, the process returns to step S21. On the other hand, when the current symmetry shift value γ is outside the allowable range, the power control unit 1253 corrects the recording power using the proportional coefficient α calculated in step S13 (step S25). Specifically, when the current recording power is represented as P and Δ symmetry shift value = (current symmetry shift value−optimum symmetry shift value), the corrected recording power P ′ is expressed as follows. .
P ′ = P−Δ symmetry shift value / α

  The above processing is repeated until the data recording is completed (step S27). That is, if the data recording is not completed, the process returns to step S21. If the data recording is completed, the process returns to the original process.

  By carrying out such processing, it is possible to absorb disturbance due to sensitivity variations in the surface of the medium and environmental changes during recording, and to realize good recording characteristics.

  Also, this time, the example was shown in the case where the media characteristic is High-to-Low (the amount of light returning to the PD after recording decreases), but Low-to-High (the amount of light returning to the PD after recording increases) ), Good recording characteristics can be realized.

[Embodiment 2]
Next, the operation of the optical disc recording / reproducing apparatus 100 in the second embodiment will be described with reference to FIG. First, the optical disc recording / reproducing apparatus 100 accepts insertion of the disc 150 by the user (step S31). Then, the CPU 125 reads the media ID data written in the predetermined area via the PD 112, the slicer 122, and the data demodulation circuit 123 (step S33), and the CPU 125 corresponds to the media ID in the memory 127, for example. The stored strategy data is read out (step S35). When data related to the allowable range of the symmetry shift value, which is an evaluation index described below, is recorded on the disk 150, the data related to the allowable range is also read out.

  Further, the CPU 125 causes writing to be performed so as to form a predetermined pit and space pattern in the trial writing area of the disk 150 in accordance with the read strategy data. In order to specify the optimum recording power, different recording powers are set in the LD driver 121 for a predetermined pit and space pattern and are written a predetermined number of times. At the same time, the PD 112 detects reflected light from the disk 150 while writing with each recording power and outputs a corresponding WRF signal to the characteristic value detection unit 124. The characteristic value detection unit 124 detects a value necessary to calculate a symmetry shift value that is an evaluation index at the timing shown in FIG.

  FIG. 9 shows (a) a pulse output waveform of a laser beam output from the LD 111 when forming 8T, 3T, 2T, and 7T pits, (b) a sampling signal indicating the timing of sampling, and (c) recording. An example of the WRF signal that is a result of detecting the reflected light of PD by the PD 112 and (d) the formed pits is shown.

The first symmetry shift value γ ₁ , which is an evaluation index in the present embodiment, is an intermediate value between the steady level wL8T at the time of space formation and the level wP8T immediately after recording a pit having a length such that the RF signal is saturated. This represents the degree of bias of the level wP2T immediately after the shortest pit is written. More specifically, the symmetry shift value γ ₁ = {(wL8T + wP8T) / 2−wP2T} / (wL8T−wP8T). That is, it is normalized by (wL8T-wP8T). This evaluation index is known to have a high correlation with the asymmetry value.

In addition, the second symmetry shift value γ ₂ that is an evaluation index in the present embodiment is a steady level wL8T at the time of space formation and a level wP8T immediately after recording a pit having a length such that the RF signal is saturated. This represents the degree of bias of the level wP3T immediately after writing the second shortest pit from the middle. More specifically, the symmetry shift value γ ₂ = {(wL8T + wP8T) / 2−wP3T} / (wL8T−wP8T). That is, it is normalized by (wL8T-wP8T). This evaluation index is also known to have a high correlation with the asymmetry value.

Further, the third symmetry shift value γ ₃ which is an evaluation index in the embodiment of the present invention is a ratio between the level wP2T immediately after writing the shortest pit and the level wP3T immediately after writing the second shortest pit. Specifically, the symmetry shift value γ ₃ = wP2T / wP3T. This evaluation index is also known to have a high correlation with the asymmetry value.

  As described above, in the case of BD and HD-DVD, the pit length at which the RF signal is saturated is 6T or more, and 8T and 7T are the pit lengths at which the RF signal is saturated. The shortest pit is a 2T pit in the case of BD or HD-DVD. The second shortest pit is a 3T pit. Accordingly, as shown in FIG. 9B, immediately after the LD output signal for forming the 8T pit, immediately after the LD output signal for forming the 3T pit, immediately after the LD output signal for forming the 2T pit, and for the LD output for forming 7T. The sampling signal is turned on immediately after the signal. The sampling signal is generated by the CPU 125 itself or a circuit that operates in response to an instruction from the CPU 125. Then, as shown in FIG. 9C, the level immediately after the LD output signal for 2T pit formation (timing B2) is specified as wP2T, and immediately after the LD output signal for 3T pit formation (timing D2). The level is specified as wP3T, and the level immediately after the LD output signal (timing A2 and C2) for pit formation of 6T or more is specified as wP8T. Further, since the steady level wL8T at the time of forming the space is necessary, in order to detect the steady level wL8T at the time of forming the space after a predetermined timing when the steady state is reached, that is, Δt after the LD output signal becomes the space forming level. The sampling signal is turned on (timing E2, F2 and G2) for detection.

  wP2T, wP3T, wP8T, and wL8T are also detected several times at a specific recording power. However, since the value may change, the average value is calculated, and the symmetry shift value is calculated using the average value. Also good.

  Note that, as shown in FIG. 9D, the pits are formed with a slight deviation from the LD output signal.

  In this way, the characteristic value detection unit 124 detects wP2T, wP3T, wP8T, and wL8T for each recording power.

  The detection value calculation unit 1251 of the CPU 125 receives the values of wP2T, wP3T, wP8T, and wL8T from the characteristic value detection unit 124, calculates the first to third symmetry shift values for each recording power, and stores them in the memory 127, for example. (Step S37).

Then, the detected value calculation unit 1251 specifies the symmetry shift value having the highest change rate from the value at the minimum recording power and the value at the maximum recording power, for each symmetry shift value (step S39). . For example, as shown in FIG. 10, a straight line b representing the relationship between the symmetry shift value γ ₁ and the recording power, a straight line c representing the relationship between the symmetry shift value γ ₂ and the recording power, and the symmetry shift value γ ₃ and the recording power. When the straight line d representing the relationship is obtained, the straight line b has the largest change rate and the symmetry shift value γ ₁ is selected. In this step, regression calculation has been performed, and the expression γ ₁ = α ₁ x + β ₁ representing the straight line b, the expression γ ₂ = α ₂ x + β ₂ representing the straight line c, and the expression γ ₃ = α ₃ representing the straight line c. x + β ₃ may be calculated, and a symmetry shift having the largest value among α ₁ , α ₂ , and α ₃ may be specified.

  Further, when the writing to the trial writing area is completed, the CPU 125 performs a process of setting the reproduction power in the LD driver 121 in order to reproduce the result of the trial writing. The PD 112 detects the reflected light from the disk 150 and outputs an RF signal to the characteristic value detection unit 124. The characteristic value detection unit 124 detects a value necessary for calculating the asymmetry value and outputs it to the CPU 125. The detection value calculation unit 1251 of the CPU 125 calculates an asymmetry value for each recording power from the detection value from the characteristic value detection unit 124 and stores it in the memory 127, for example (step S41).

Next, the optimization determining unit 1252 identifies the recording power at which the asymmetry value is optimal (step S43). The corresponding recording power is specified by setting the asymmetry value closest to the predetermined optimum asymmetry value as the optimum. Similarly, the optimum value (γ ′ _{1 in} the example of FIG. 10) corresponding to the optimum recording power is also specified for the symmetry shift value (γ _{1 in} the example of FIG. 10) specified in step S39.

  Further, the power control unit 1253 performs regression calculation from the symmetric deviation value stored in the memory 127 and specified in step S39 and the corresponding recording power value, and the symmetric deviation value minus the recording power proportional coefficient. Is calculated and stored in the memory 127 (step S45). A straight line as shown in FIG. 10 is specified for the symmetry shift value specified in step S39. Note that this step is skipped when the regression calculation is performed in step S39.

  Thereafter, the power control unit 1253 of the CPU 125 sets the optimum recording power in the LD driver 121 and performs data recording (step S47). The processing in this data recording is the same as in FIG. However, it is only necessary to calculate the symmetry shift value specified in step S39, and only the value necessary for it is detected from the WRF signal.

  By carrying out such processing, it is possible to absorb disturbance due to sensitivity variations in the surface of the medium and environmental changes during recording, and to realize good recording characteristics. In particular, since the adaptive control of the recording power is performed using the symmetry shift value that is most affected by the recording power from more evaluation indexes, the asymmetry value fluctuation can be dealt with early.

[Embodiment 3]
Next, the operation of the optical disc recording / reproducing apparatus 100 in the third embodiment will be described with reference to FIG. First, the optical disc recording / reproducing apparatus 100 accepts insertion of the disc 150 by the user (step S51). Then, the CPU 125 reads the media ID data written in the predetermined area via the PD 112, the slicer 122, and the data demodulation circuit 123 (step S53), and the CPU 125 corresponds to the media ID in the memory 127, for example. The stored strategy data is read out (step S55). When data related to the threshold value of the standard deviation σ of the symmetry shift value, which is an evaluation index described below, is recorded on the disk 150, the data related to the threshold value is also read out.

  Further, the CPU 125 causes writing to be performed so as to form a predetermined pit and space pattern in the trial writing area of the disk 150 in accordance with the read strategy data. In order to specify the optimum recording power, different recording powers are set in the LD driver 121 for a predetermined pit and space pattern and are written a predetermined number of times. At the same time, the PD 112 detects reflected light from the disk 150 while writing with each recording power and outputs a corresponding WRF signal to the characteristic value detection unit 124. The characteristic value detection unit 124 detects a value necessary for calculating the symmetry shift value at the timing shown in FIG. That is, the characteristic value detection unit 124 detects wP2T, wP3T, wP8T, and wL8T for each recording power.

  The detection value calculation unit 1251 of the CPU 125 receives the values of wP2T, wP3T, wP8T, and wL8T from the characteristic value detection unit 124, calculates the first to third symmetry shift values for each recording power, and stores them in the memory 127, for example. (Step S57). The definitions of the first to third symmetry shift values are the same as those in the second embodiment.

  When the writing to the trial writing area is completed, the CPU 125 performs a process of setting the reproduction power in the LD driver 121 in order to reproduce the result of the trial writing. The PD 112 detects the reflected light from the disk 150 and outputs an RF signal to the characteristic value detection unit 124. The characteristic value detection unit 124 detects a value necessary for calculating the asymmetry value and outputs it to the CPU 125. The detection value calculation unit 1251 of the CPU 125 calculates an asymmetry value for each recording power from the detection value from the characteristic value detection unit 124 and stores it in the memory 127, for example (step S59).

  Next, the optimization determining unit 1252 identifies the recording power at which the asymmetry value is optimal (step S61). The corresponding recording power is specified by setting the asymmetry value closest to the predetermined optimum asymmetry value as the optimum.

Further, the detected value calculation unit 1251 calculates the standard deviation σ of the symmetry shift value for each recording power and stores it in the memory 127 (step S63). At this time, the detection value calculation unit 1251 specifies each symmetry shift value at the optimum recording power. Here, the optimal value of the _first symmetric shift value γ ₁ is γ ′ ₁ , the optimal value of the second symmetric shift value γ ₂ is γ ′ _2, and the optimal value of the third symmetric shift value γ ₃ is γ. ' ₃ The standard deviation σ of the symmetry shift value is as follows.

  The standard deviation σ is calculated for each recording power, and the standard deviation σ at the optimum recording power is zero.

  Then, a graph as shown in FIG. 12 can be drawn. Since the standard deviation σ at the optimum recording power is 0 and there is no negative value from the definition of the standard deviation σ, a V-shaped line e can be drawn as shown in FIG.

Further, the power control unit 1253 performs regression calculation from the standard deviation σ value stored in the memory 127 and the corresponding recording power value, calculates the standard deviation σ−recording power proportionality coefficient, and the memory 127. (Step S65). Basically, the regression calculation is performed separately for the proportional coefficient α ₁ when the recording power is equal to or higher than the optimum recording power and the proportional coefficient α ₂ when the recording power is less than or equal to the optimum recording power. For simplicity, for example, the proportionality coefficient α ₁ in the case of a recording power equal to or higher than the optimum recording power may be used, and the proportionality coefficient in the case of a recording power lower than the optimum recording power may be set to −α ₁ . α ₂ may be calculated and α ₁ may be set to −α ₂ .

  Thereafter, the power control unit 1253 of the CPU 125 sets the optimum recording power in the LD driver 121 to perform data recording (step S67). Processing in this data recording will be described with reference to FIG.

  First, the current first to third symmetry shift values are calculated and stored in the memory 127 as in step S57 while the data recording is performed at the recording power that is the optimum recording power as usual. Step S71). Since the CPU 125 knows what pits and spaces are formed, the sampling signal can be output at an appropriate timing. For example, each symmetric deviation value is calculated by averaging values sampled several times for each predetermined period. It may be calculated every time data that can calculate each symmetry shift value is acquired.

  Further, the detected value calculation unit 1251 calculates the current standard deviation σ from the current first to third symmetry shift values, and stores it in the memory 127 (step S73).

  Then, the optimization determination unit 1252 determines whether or not the current standard deviation σ is equal to or less than a threshold value of the standard deviation σ recorded in advance in the disk 150 or the memory 127 (step S75). From the definition of the standard deviation σ, since σ is 0 or more, a positive threshold value is set.

If it is determined that the current standard deviation σ is equal to or smaller than the threshold value, the process returns to step S71. On the other hand, if the current standard deviation σ exceeds the threshold value, the power control unit 1253 corrects the recording power using the proportionality coefficient α ₁ or α ₂ calculated in step S65 (step S77). Specifically, α ₁ is used if the sign of γ ₁ −γ ′ ₁ is positive, and α ₂ is used if it is negative. γ ₂ -γ 'may be based on the _second code. The current recording power is expressed as P, and when Δ standard deviation = (current standard deviation−optimal value of standard deviation σ), the corrected recording power P ′ is expressed as follows.
P ′ = P−Δ standard deviation / α
However, α is α ₁ or α ₂ .

  The above process is repeated until the data recording is completed (step S79). That is, if the data recording is not completed, the process returns to step S71, and if the data recording is completed, the process returns to the original process.

  As described above, even if an evaluation index that integrates the first to third symmetry shift values is used, the symmetry value is brought close to an appropriate value by adaptively controlling the recording power so as to optimize them. Will be able to.

  Although the embodiments of the invention of the present invention have been described above, these are only examples.

  That is, the use of the standard deviation σ is merely an example, and another evaluation index that integrates the first to third symmetry shift values may be employed. Moreover, although the example which uses the 1st thru | or 3rd symmetry shift value was shown, you may make it define and use another symmetry shift value.

  Further, the functional blocks in the functional block diagram of FIG. 1 are merely examples, and may not necessarily correspond to an actual module configuration.

Further, in the example of FIG. 1, an example in which a television receiver and a remote controller are assumed as the input / output system 130 is shown, but for example, a personal computer may be connected instead. The optical disk recording / reproducing apparatus 100 may be integrated with a personal computer.

It is a functional block diagram concerning an embodiment of the invention. It is a figure which shows the main process flow in the 1st Embodiment of this invention. (A) thru | or (d) is a figure which shows the timing chart for demonstrating the sampling in the 1st Embodiment of this invention. It is a figure for demonstrating an asymmetry value. It is a figure which shows the relationship between recording power and a symmetry shift value. It is a figure which shows the processing flow of the data recording process in the 1st Embodiment of this invention. (A) shows the state of the WRF signal optimal conditions, (b) shows the state of the WRF signal during under-power, a diagram showing the state of (c) is WRF signal during overpower. It is a figure which shows the main processing flow in the 2nd Embodiment of this invention. (A) thru | or (d) is a figure which shows the timing chart for demonstrating the sampling in the 2nd and 3rd embodiment of this invention. It is a figure which shows the relationship between recording power and the 1st thru | or 3rd symmetry shift value. It is a figure which shows the main processing flow in the 3rd Embodiment of this invention. It is a figure showing the relationship between the recording power and the standard deviation σ of the symmetry shift value. It is a figure which shows the processing flow of the data recording process in the 3rd Embodiment of this invention.

Explanation of symbols

100 optical disk recording / reproducing apparatus 110 pickup unit 111 LD
112 PD 113 Collimating lens 114 Objective lens 115 Detection lens 116 Beam splitter 121 LD driver 122 Slicer 123 Data demodulating circuit 124 Characteristic value detection unit 125 CPU
127 memory 128 I / F
130 Input / Output System 131 Display Unit 132 Operation Unit 150 Disk 1251 Detection Value Calculation Unit 1252 Optimization Judgment Unit 1253 Power Control Unit 1254 Memory Circuit

Claims (13)

While recording on the disc with the optimum recording power, the first part, which is the part after recording the shortest pit, and the pit with a length that saturates the RF signal are recorded. a second portion is a partial, a detecting means for detect the value of the light receiving signals corresponding to the intensity of light reflected from the disk and the third portion is a portion of the after space formation starting after a predetermined time,
From the value before Symbol the photodetection signal detected by the detection means, said third space formed at a steady level obtained with the portion of the intermediate level in the second part, the level of the first portion Index value calculation means for calculating an index value of a specific evaluation index representing the degree of bias of
Power correction means for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated by the index value calculation means ;
Optical disk recording apparatus which have a. Detecting means for detecting the value of the received light signal corresponding to the intensity of the reflected light from the disk at a predetermined timing while recording on the disk with the recording power that is the optimum recording power;
Index value calculation means for calculating an index value of a specific evaluation index from the value of the received light signal detected by the detection means;
Power correction means for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated by the index value calculation means;
Have
The first timing is the part after recording the shortest pit, the second timing is the part after recording the shortest pit after the shortest pit, and the third timing is the RF signal It is a part after recording a pit of a length that saturates, and the fourth timing is a part after a predetermined time has elapsed after the start of space formation,
The specific evaluation index is a first level representing a degree of level deviation at the first timing from an intermediate level between a steady level at the time of space formation obtained at the fourth timing and a level at the third timing. A second index that represents the degree of deviation of the level at the second timing from the middle of the index and the steady level at the time of space formation obtained at the fourth timing and the level at the third timing; Of the third index representing the ratio of the level at the first timing and the level at the second timing, the index is most susceptible to the influence of the recording power,
When the first index is adopted, the predetermined timing includes the fourth, third, and first timings, and when the second index is adopted, the predetermined timing is the first timing. 4, when the third index is adopted, including the third and second timings, the predetermined timing includes the first and second timings,
Optical disk recording device. The first part which is the part after recording the shortest pit and the part after the short pit is recorded next to the shortest pit while recording on the disc with the recording power which is the optimum recording power The second portion, the third portion that is a portion after recording a pit having a length that saturates the RF signal, and the fourth portion that is a portion after a predetermined time has elapsed after the start of space formation. Detecting means for detecting the value of the received light signal corresponding to the intensity of the reflected light from the disk;
From the value of the light reception signal detected by the detection means, the level of the first portion from the intermediate level between the steady level at the time of forming the space obtained in the fourth portion and the level in the third portion. The first index representing the degree of deviation, and the degree of level deviation in the second part from the middle between the steady level at the time of forming the space obtained in the fourth part and the level in the third part. An index value calculating means for calculating an index value of a specific evaluation index by integrating a second index to be expressed, and a third index representing a ratio of the level in the first portion and the level in the second portion;
Power correction means for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated by the index value calculation means;
An optical disc recording apparatus having Based on the index value of the specific evaluation index for the plurality of recording powers used for recording on the disc to specify the initial optimal recording power corresponding to the optimal asymmetry value, the recording power and the specific And an extraction means for extracting a relationship with the index value of the evaluation index of
The power correction means includes
The specific evaluation calculated by the index value calculation means from the relationship extracted by the extraction means and the optimum index value corresponding to the initial optimum recording power, which is the evaluation value of the specific evaluation index. The optical disc recording apparatus according to any one of claims 1 to 3 , wherein the corrected recording power is determined based on a deviation of the index values of the indices. The optical disc recording apparatus according to claim 4 , further comprising: means for specifying the optimum index value from the initial optimum recording power based on an index value of the specific evaluation index for the plurality of recording powers . The specific evaluation index is
The magnitude of the divergence between the index value of the first index and the target value of the first index, the magnitude of the divergence between the index value of the second index and the target value of the second index, The optical disc recording apparatus according to claim 3 , wherein the optical disc recording apparatus is an evaluation index related to a value obtained by summing an index value of an index of 3 and a magnitude of deviation between a target value of the third index . Data relating to an allowable range for the optimum index value of the specific evaluation index is stored in the disk or memory;
The power correction means includes
If the index value of the specific evaluation index calculated by the index value calculating means becomes the allowable range, the optical disc recording apparatus of any one of claims 1 to 3 carried out correction of the power. While recording on the disc with the optimum recording power, the first part, which is the part after recording the shortest pit, and the pit with a length that saturates the RF signal are recorded. a second portion is a partial, a detecting step of detect the value of the light receiving signals corresponding to the intensity of light reflected from the disk and the third portion is a portion of the after space formation starting after a predetermined time,
From the value of said detected light signal before Symbol detection step, the third space formed at a steady level obtained with the portion of the intermediate level in the second part, the level of the first portion An index value calculating step for calculating an index value of a specific evaluation index representing the degree of bias of
A power correction step for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated in the index value calculating step ;
An optical disc recording method including: A detection step of detecting a value of a received light signal corresponding to the intensity of reflected light from the disk at a predetermined timing while recording on the disk with a recording power that is an optimum recording power;
An index value calculating step of calculating an index value of a specific evaluation index from the value of the received light signal detected in the detecting step;
A power correction step for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated in the index value calculating step;
Including
The first timing is the part after recording the shortest pit, the second timing is the part after recording the shortest pit after the shortest pit, and the third timing is the RF signal It is a part after recording a pit of a length that saturates, and the fourth timing is a part after a predetermined time has elapsed after the start of space formation,
The specific evaluation index is a first level representing a degree of level deviation at the first timing from an intermediate level between a steady level at the time of space formation obtained at the fourth timing and a level at the third timing. A second index that represents the degree of deviation of the level at the second timing from the middle of the index and the steady level at the time of space formation obtained at the fourth timing and the level at the third timing; Of the third index representing the ratio of the level at the first timing and the level at the second timing, the index is most susceptible to the influence of the recording power,
When the first index is adopted, the predetermined timing includes the fourth, third, and first timings, and when the second index is adopted, the predetermined timing is the first timing. 4, when the third index is adopted, including the third and second timings, the predetermined timing includes the first and second timings,
Optical disc recording method. The first part which is the part after recording the shortest pit and the part after the short pit is recorded next to the shortest pit while recording on the disc with the recording power which is the optimum recording power The second portion, the third portion that is a portion after recording a pit having a length that saturates the RF signal, and the fourth portion that is a portion after a predetermined time has elapsed after the start of space formation. A detection step for detecting a value of a received light signal corresponding to the intensity of reflected light from the disc;
From the value of the light reception signal detected in the detection step, the level in the first portion from the middle between the steady level at the time of space formation obtained in the fourth portion and the level in the third portion. The first index representing the degree of deviation, and the degree of level deviation in the second part from the middle between the steady level at the time of forming the space obtained in the fourth part and the level in the third part. An index value calculating step of calculating an index value of a specific evaluation index by integrating a second index to be expressed, and a third index representing a ratio of the level in the first portion and the level in the second portion;
A power correction step for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated in the index value calculating step;
An optical disc recording method including: While recording on the disc with the optimum recording power, the first part, which is the part after recording the shortest pit, and the pit with a length that saturates the RF signal are recorded. a second portion is a portion, if it detects a value of the light receiving signals corresponding to the intensity of light reflected from the disk and the third part is a part after a predetermined time has elapsed after the space formation started, detected Further , a specific value representing the degree of level deviation in the first portion from the middle between the steady level at the time of space formation obtained in the third portion and the level in the second portion is obtained from the value of the received light signal. An index value calculating step for calculating an index value of the evaluation index;
A power correction step of correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated by the index value calculating step ;
A program that causes a processor to execute. While recording on the disc with the recording power that is the optimum recording power, when detecting the value of the received light signal corresponding to the reflected light intensity from the disc at a predetermined timing, from the detected value of the received light signal, An index value calculating step for calculating an index value of a specific evaluation index,
A power correction step for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated in the index value calculating step;
To the processor,
The first timing is the part after recording the shortest pit, the second timing is the part after recording the shortest pit after the shortest pit, and the third timing is the RF signal It is a part after recording a pit of a length that saturates, and the fourth timing is a part after a predetermined time has elapsed after the start of space formation,
The specific evaluation index is a first level representing a degree of level deviation at the first timing from an intermediate level between a steady level at the time of space formation obtained at the fourth timing and a level at the third timing. A second index that represents the degree of deviation of the level at the second timing from the middle of the index and the steady level at the time of space formation obtained at the fourth timing and the level at the third timing; Of the third index representing the ratio of the level at the first timing and the level at the second timing, the index is most susceptible to the influence of the recording power,
When the first index is adopted, the predetermined timing includes the fourth, third, and first timings, and when the second index is adopted, the predetermined timing is the first timing. 4, when the third index is adopted, including the third and second timings, the predetermined timing includes the first and second timings,
program. The first part which is the part after recording the shortest pit and the part after the short pit is recorded next to the shortest pit while recording on the disc with the recording power which is the optimum recording power The second portion, the third portion that is a portion after recording a pit having a length that saturates the RF signal, and the fourth portion that is a portion after a predetermined time has elapsed after the start of space formation. When the value of the received light signal corresponding to the intensity of the reflected light from the disk is detected, the steady level at the time of forming the space obtained in the fourth part and the level in the third part are obtained from the detected value of the received light signal Between the first index indicating the degree of level deviation in the first portion, the steady level at the time of the space formation obtained in the fourth portion, and the level in the third portion. And a second index representing the degree of level deviation in the second part and a third index representing the ratio of the level in the first part and the level in the second part from the middle An index value calculating step for calculating an index value of the specific evaluation index,
A power correction step for correcting the recording power to be the optimum recording power according to the index value of the specific evaluation index calculated in the index value calculating step;
A program that causes a processor to execute.

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