JP4613891B2 - Optical disc recording / reproducing apparatus, optical disc recording / reproducing method, and optical disc recording / reproducing program - Google Patents

Description

The present invention relates to an optical disk recording and reproducing apparatus, relates to an optical disc recording and reproducing method及beauty optical disk recording and reproducing program, when the recording with a laser beam, particularly a rewritable disc-shaped optical recording medium having a plurality of recording layers (an optical disk) , from the detection of the optimum recording power condition by reproducing the test recording signal, the optical disc recording and reproducing apparatus for recording and reproducing user data in the optimum recording power condition, an optical disc recording and reproducing method及beauty optical disc recording and reproducing program.

  In the optical disk recording / reproducing apparatus, a predetermined test is performed while changing the recording conditions on the target optical disk before the start of actual recording (actual recording) on the data area of the optical disk such as a DVD-R disk or a DVD-RW disk. The recording signal is trial-written, and the test-written area is reproduced to obtain the optimum recording condition based on the characteristics of the obtained reproduction test recording signal, and actual recording is performed under this optimum recording condition. Thereby, good recording quality can be obtained. Obtaining the optimum recording condition based on the reproduction test recording signal from the trial-written area is called optimum recording power control (OPC).

  By the way, in recent years, the development of DVD-R discs and DVD-RW discs having two recording layers has been promoted due to a demand for an increase in recording capacity. FIG. 15 shows a schematic cross-sectional view of an example of this dual-layer DVD-R disc and dual-layer DVD-RW disc. As shown in the figure, in a single-sided dual-layer DVD-R disc or DVD-RW disc, a first recording layer 301 and a second recording layer 302 are stacked in the optical axis direction of a light beam 402 during recording and reproduction. The light beam 402 is condensed on the first recording layer 301 by the objective lens 401 in the optical pickup, or is transmitted through the first recording layer 301 and is condensed on the second recording layer 302.

The recording areas of the first recording layer 301 closer to the optical pickup are, from the inner circumference to the outer circumference, a PCA area (Power Calibration Area) 311, an RMA area (Recording Management Area) 312, and a lead-in area (Lead- In) 313, a data area (Data Area) 314, and a middle area (Middle Area) 315.
The recording area of the second recording layer 302 includes a PCA area 321, an RMA area 322, a lead-out area 323, a data area 324, and an intermediate area from the inner periphery toward the outer periphery. It is divided into an area (Middle Area) 325.

  The OPC process for acquiring the optimum recording condition is performed using the PCA area 311 and the PCA area 321. The RMA area 312 and the RMA area 322 are recording management areas in which information for managing the transition of the recording state of the lead-in area 313, the data areas 314, 324, and the lead-out area 323 and OPC information is recorded. The A part of the lead-in area 313 has an area called a control data zone, in which information on the entire disk such as the size of the disk, recording power, recording waveform pattern, ratio of erasing power, etc. is recorded. Conditions are recorded in advance as pre-pit data information at the time of disc manufacture.

Also, in the track groove of an optical disk such as a DVD-R disk or a DVD-RW disk, address information on the disk is recorded as track groove information (land prepit: LPP) at the pre-format stage at the time of disk manufacture. (For example, refer to Patent Document 1).
Recording on a DVD-R disc or DVD-RW disc is performed based on the address information of the LPP. In addition to the address information, the LPP stores reference conditions for recording such as recording power and recording waveform pattern.

  Before actual recording in the data area of the first recording layer 301, OPC is performed in the PCA area 311 of the first recording layer 301, and before actual recording in the data area of the second recording layer 302, the second layer is recorded. OPC is performed in the PCA area 321 of the recording layer 302. The optimum recording power is different depending on the thickness of the first recording layer 301 and the second recording layer 302, and even in the same optical disc, the optimum power may be different depending on the pulse strategy at the time of writing or the difference in the laser waveform. It is necessary to acquire the recording power.

  The DVD-RW disc is an optical disc that can be rewritten a plurality of times, and a phase change material is used for the recording layer. For recording on the first recording layer of the DVD-RW disc, laser light whose recording power changes to ternary values Pw, Pe, Pb as shown in FIG. 16A, for example, is used. Pw is writing power (hereinafter also referred to as recording power), and the state of the recording layer of the optical disk is changed from the crystalline state to the amorphous state by the laser beam of this power Pw to form pits. Pe is an erasing power. When the recording layer is in an amorphous state, the laser beam having the power Pe returns to a crystalline state and erases (overwrites) old pits. Pb is a bias power, which corresponds to the power at the bottom of a divided pulse obtained by so-called pulse division recording, and serves to prevent heat due to laser light irradiation during recording by the laser light having this power Pb. As shown in FIG. 16A, when the power with respect to the laser light changes in a predetermined order, pits as shown in FIG. 16B are formed on the optical disc.

  For example, an asymmetry value (a parameter representing the asymmetry of a high-frequency signal) or a value γ obtained from a modulation factor is used as a characteristic parameter for determining the quality of a recording state when performing OPC of a phase change optical disc (for example, , See Patent Document 2). In Patent Document 2, first, the erasing power and the bias power are fixed, the writing power (recording power) is changed, the test recording signal is recorded, and the test signal recording portion is reproduced to determine whether the recording state is good or bad. The optimum writing power is obtained by measuring the characteristic parameter to be measured.

  Next, the write power is used, the bias power is fixed, the erasing power is changed, the test recording signal is recorded, and the test recording signal recording portion is reproduced to determine the quality of the recording state. The optimum erasing power is obtained by measuring the parameters. Finally, using these writing power and erasing power, changing the bias power, writing the test recording signal, reproducing the test recording signal recording portion, and measuring the characteristic parameters for judging the quality of the recording state Thus, the optimum bias power is obtained.

Patent Document 2 describes a method of recording actual user data (actual recording) in a data area based on the writing power, erasing power, and bias power obtained as described above.
Patent Document 2 describes that an asymmetry value β or γ value or an error rate is used as a characteristic parameter for determining the quality of a recording state.

JP-A-10-293926 Japanese Patent No. 3259642

  However, with regard to a rewritable optical disc having two recording layers, for example, an attempt was made to obtain an optimum recording condition similar to that of a conventional single-layer DVD-RW optical disc described in Patent Document 2, for example. In the first recording layer closer to the optical pickup, the RF signal reproduction characteristics tend to differ between the first recording time, the second recording time, and the third recording time depending on the number of repeated recordings. As a result, there is a problem that it is difficult to ensure optimum recording quality due to variations in the recording quality. Stable RF signal reproduction characteristics are obtained after the fourth to fifth recordings.

  FIG. 17 shows the measurement results of the number of times of recording and reproduction jitter when recording is performed using the same recording conditions. As can be seen from the figure, the reproduction jitter at the time of the second recording is relatively poor, and the reproduction jitter is relatively good over the 10th and subsequent 1000 times. Here, “reproduction jitter” is generally a difference between a rising edge and a falling edge of a clock generated from a reproduction signal by a phase locked loop (PLL) circuit and a signal obtained by binarizing the reproduction signal with respect to the clock. It is a value (unit%) obtained by multiplying the value obtained by integrating and averaging time by the clock period and multiplying by 100 (unit%). It can be said that the smaller the reproduction jitter value, the better the reproduction state.

  18A and 18B show the measurement results of the recording power Pw and the reproduction jitter, and the measurement results of the erasing power Pe and the reproduction jitter. As can be seen from FIGS. 18A and 18B, it can be seen that the reproduction jitter changes greatly depending on the change of the recording power Pw or the erasing power Pe. Further, in the characteristics of the erasing power and reproduction jitter shown in FIG. 18B, the optimum erasing power Pe that minimizes the reproduction jitter at the time of the first recording (initial time) and the number of rewrites (overwrite times) are the first. It can be seen that there is a difference between the optimum erasing power Pe that minimizes the reproduction jitter at the time of (DOW1) and 10th (DOW10) recording.

  It can be seen from FIG. 18 (A) that the allowable range of recording power for obtaining a small value of reproduction jitter, that is, the margin of recording power with respect to reproduction jitter, is relatively wide. On the other hand, it can be seen from FIG. 18B that the erasure power margin changes with the number of rewrites and the allowable range of the optimum erasure power is narrow. For example, in FIGS. 18A and 18B, in the case of the 10th rewrite (DOW10), the recording power is about ± 2. It can be seen that the erase power is 2 mW and the erase power is about ± 0.4 mW, and in particular, the power setting error of the erase power tends to affect the deterioration of the jitter.

  Further, FIG. 19 shows the relationship between the ratio of the erasing power to the recording power (hereinafter referred to as ε) and the reproduction jitter, the single-layer DVD-RW, and the two-layer DVDs of A company, B company, and C company. FIG. 6 is a characteristic diagram showing each of the first recording layer of -RW. As can be seen from FIG. 19, ε has a much narrower tolerance range of the reproduction jitter with respect to the first recording layer of the two-layer DVD-RW than the reproduction jitter of the single-layer DVD-RW. Even in DVD-RWs, the above margin is slightly different depending on the manufacturer (Company A, Company B, Company C).

The present invention has been made in view of the above points, and paying attention to the first recording layer closest to the optical pickup of the multilayer optical disk, in particular, reducing the setting error of the erasing power so that the reproduction jitter after recording is in the best state. optical disc recording and reproducing apparatus capable of detecting an optimum recording condition for, and to provide an optical disc recording and reproducing method及beauty optical disc recording and reproducing program.

To achieve the above object, according to a first aspect of the present invention, there is provided an optical disc recording / reproducing apparatus for performing recording / reproduction using a laser beam having a set power on a rewritable optical disc having a multi-layer recording layer. Recording power to change the recording layer from a crystalline state to an amorphous state, an erasing power to change the recording layer from an amorphous state to a crystalline state, and a bias power to prevent thermal diffusion during recording to the recording layer Recording means for recording a test recording signal in a predetermined area of the optical disk by a laser beam in which the set recording power, erasing power and bias power are changed in a predetermined order, and an optical disk on which the test recording signal is recorded by the recording means Erasing power whose level changes stepwise with the power related to the set erasing power as a reference A DC erasure unit for recording with a laser beam having only a certain DC erasing power, and a region recorded with the DC erasing power by the DC erasing unit are reproduced, and the modulation degree of the reproduced signal and the normalized gradient of the modulation degree are reproduced. Recording state detecting means for detecting at least one of a γ value which is a parameter indicating characteristics and a parameter (β value or asymmetry value) representing asymmetry of the reproduction signal, and recording with DC erasing power by the DC erasing means A determination unit that determines a detection value that matches a predetermined detection value or detection condition for DC erasing power among the values detected by the recording state detection unit from a plurality of areas having different erasing powers; the erasing power value detected value is recorded for matching area means to determine the level of optimal erase power for the optical disk recording by multiplying a predetermined coefficient Comprising a calculation unit, before the recording of the test recording signal, and initialization means for DC erasing optical disk initialization power was set to 2.5 times the value 1.5 times the erase power recommended, optical disc An optimum erasing power value at the time of recording is derived.

  In the present invention, recording was performed with a DC erasing power on a rewritable optical disc having a plurality of recording layers, and among the values detected by the recording state detecting means from a plurality of areas having different erasing powers, When an optical disc is recorded by obtaining an optimum erasing power level by multiplying an erasing power value recorded for a region where the detected value matches a predetermined detection value or detection condition for DC erasing power by a predetermined coefficient. The optimum erasing power value can be derived.

In order to achieve the above object, a second invention is an optical disc recording / reproducing method for performing recording / reproduction using a laser beam having a set power on a rewritable optical disc having a multilayer recording layer. Recording power for changing the recording layer from the crystalline state to the amorphous state under predetermined recording conditions, erasing power for changing the recording layer from the amorphous state to the crystalline state, and thermal diffusion during recording to the recording layer A first step of setting a bias power and recording a test recording signal in a predetermined area of the optical disc by a laser beam in which the set recording power, erasing power and bias power are changed in a predetermined order; The area of the optical disc on which the test recording signal is recorded is based on the power related to the set erasing power, and the level is stepwise. A second step of performing recording by a laser beam of a DC erase power only an erase power which changes, by reproducing the region subjected to record a DC erase power by a second step, the modulation degree of the reproduced signal, A third step of detecting at least one of a γ value that is a parameter indicating a normalized slope characteristic of the modulation degree and a parameter (β value or asymmetry value) that indicates the asymmetry of the reproduction signal; was record in DC erase power by the step, matching among the plurality of erasing power are different regions of the values respectively detected by the third step, the predetermined detected value or detection condition for DC erasing power a fourth step of determining a detection value, the erase power value detected value is recorded for matching region in the fourth step, when the optical disc recording by multiplying a predetermined coefficient A fifth step of obtaining a level of optimum erasing power, early before performing the recording of the test recording signal in the first step was set to 2.5 times the value 1.5 times the erase power Recommended And a sixth step of DC erasing the optical disk with the conversion power, and an optimum erasing power value at the time of optical disk recording is derived.

In order to achieve the above object, an optical disc recording / reproducing program according to a third aspect of the invention is an optical disc recording method for recording / reproducing a rewritable optical disc having a multi-layered recording layer with a laser beam using a computer. A playback program, on a computer,
Recording power for changing the recording layer from the crystalline state to the amorphous state under predetermined recording conditions, erasing power for changing the recording layer from the amorphous state to the crystalline state, and preventing thermal diffusion during recording to the recording layer set a bias power, the set recording power, the first step causes the recording test recording signal in a predetermined area of the optical disk by a laser beam of varying the erase power and bias power in a predetermined order, the first step Second, recording is performed on a region of an optical disk on which a test recording signal is recorded by using only laser light having only DC erasing power, which is erasing power whose level changes stepwise, with reference to power related to the set erasing power . a step of, by reproducing the region was recorded in the DC erase power by a second step, the modulation degree of the reproduction signal Modulation factor normalized γ value is a parameter indicating the inclination characteristics of, and a third step makes detecting at least one of the parameters (beta value or asymmetry value) representing the asymmetry of the reproduction signal, the second was record in DC erase power by the step, matching among the plurality of erasing power are different regions of the values respectively detected by the third step, the predetermined detected value or detection condition for DC erasing power a fourth step of determining a detection value, the erase power value detected value is recorded for matching region in the fourth step, the optimum erasing power for an optical disc recording by multiplying a predetermined coefficient Before the test recording signal is recorded in the fifth step and the first step, the initial power is set to 1.5 to 2.5 times the recommended erasing power. De Characterized in that to execute a sixth step of DC erase disk. In the present invention, the optimum erasing power level of the optical disk can be obtained by a computer.

  According to the present invention, a recording state detection unit that performs recording on a rewritable optical disc having a plurality of recording layers while varying the DC erasing power of the laser light, from a plurality of areas having different DC erasing powers. Among the detected values, the optimum erase power is obtained by multiplying the DC erase power value recorded for the area where the detected value matches the predetermined detection value or detection condition for the DC erase power by a predetermined coefficient. The optimum erasing power value at the time of optical disc recording is derived by obtaining the level of the optical disc, and in order to perform optimum recording with a small margin of erasing power of the first recording layer closest to the optical pickup of the multilayer optical disc in particular. Can satisfy the requirement that an accurate erasing power detection technique is required, thereby enabling recording with good jitter.

  Further, according to the present invention, after the recording mark is erased while changing the test recording area stepwise with the DC erasing power, the area is reproduced, and the modulation degree and the modulation degree of the reproduction signal are normalized. At least one of a γ value, which is a parameter indicating inclination characteristics, and a parameter (β value or asymmetry value) indicating the asymmetry of the reproduction signal is detected, and the detection characteristics change abruptly and erasure is suddenly performed. Using the fact that a point can be detected with little influence on the repetitive recording characteristics and multiplying a predetermined coefficient based on the erasing power of this point, a highly accurate erasing power can be derived (this accuracy is high and optimal) An experimental result that the error is within 2% with respect to the erasing power is obtained).

  Further, according to the present invention, the recording power is calculated from the derived erasing power using the ratio ε of the erasing power to the recording power from the optical disc information or the device memory, so that the OPC processing with the optimum recording power can be omitted. In addition, the number of OPC processes can be reduced and the startup time of the drive device can be shortened.

  Further, according to the present invention, in order to obtain the optimum writing power, the DC erasing power matched by the judging means is used as a reference value, and a predetermined coefficient for obtaining the erasing power is obtained by multiplying the reference value. Since the pre-pit area or track groove of the optical disc is pre-recorded at the manufacturing stage, even when an optical disc of a newly entered optical disc manufacturer or an optical disc having no data in the apparatus memory is subjected to OPC processing The optimum erasing power can be obtained using information in the optical disk.

  Next, each embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a block diagram of an embodiment of an optical disk recording / reproducing apparatus according to the present invention. The rewritable optical disc recording / reproducing apparatus 15 of the present embodiment shown in the figure mainly shows the control block configuration of the part according to the present invention. An optical disc recording / reproducing apparatus 15 uses an optical pickup (PU) 2 to reproduce and record an RF signal on a rewritable optical disc 1 in which a plurality of recording layers are laminated in the optical axis direction of a recording / reproducing laser beam. Write. Here, as an example, the optical disc 1 will be described as a single-sided dual-layer optical disc having a cross-sectional structure shown in FIG. The RF signal reproduced from the optical disk 1 by the optical pickup 2 is input to the signal processing circuit 3, data demodulated (not shown), and sent to a system control device (not shown) such as a computer or a DVD recorder via an external interface. Is output.

  The signal processing circuit 3 includes a recording state detecting means 4, a DC erasing means 5, a recording means 6, and the like. From an RF signal reproduced from the optical disk 1 by the optical pickup 2, an internal demodulating means (not shown) is used. Demodulation is performed to obtain information (disc structure, recommended recording power, recording strategy, recording power / erasing power ratio ε, etc.) of the optical disc 1 and stored in the device memory 14 via the internal bus 10 and the control circuit 11. When recording data on the optical disk 1, the control circuit 11 sends the write address, write power (recording power, erasing power, bias power) and recording strategy setting information to the recording means 6 via the internal bus 10 in the signal processing circuit 3. To the recording means 6. The recording means 6 writes to a predetermined address on the optical disc 1 by the optical pickup 2 based on these setting information.

  In the first embodiment, a short recording mark of a recording waveform pattern as a test recording signal (for example, in the case of an 8/16 modulation signal, 3T (T is the cycle of the channel clock; the same applies hereinafter) to 7T. An optical disc 1 using a test recording signal or a random pattern signal of a recording waveform pattern in which an arbitrary mark signal) and a long mark (for example, an arbitrary mark signal of 8T to 14T in the case of an 8/16 modulation signal) are mixed. Make a test record.

  The laser power waveform for the phase change type optical disc 1 is formed using a write waveform (recording power Pw, erasing power Pe, bias power Pb and recording strategy) as shown in FIG. 16 to form recording marks. The power of the laser light emitted from the optical pickup 2 is controlled with high accuracy to a writing power value set by ALPC (Automatic Laser Power Control) means (not shown) inside the recording means 6. In normal OPC processing, recording is performed by changing the write power stepwise to the address of a predetermined block in the OPC area of the optical disc 1. This operation can be performed by the recording means 6. When actual recording (actual recording) is performed, continuous data recording can be performed by setting an optimum writing power in the recording means 6.

  In the detection of the optimum erasing power of the present embodiment, the recording means 6 first performs test recording of the OPC area with the writing power and the recording strategy with the recording conditions made constant. The writing power with a constant recording condition is set by the recording means 6, for example, a recommended recording power value (hereinafter referred to as “Pind”) read from the optical disk 1 or the device memory 14 is set as a fixed value of the recording power. Alternatively, the erase power value (= ε · Pind) obtained by calculation from the value ε of the recording power and erase power read from the device memory 14 and the recommended recording power value (Pind) is set as a fixed value of the erase power. Then, the recommended bias power value read from the device memory 14 is set as a fixed value of the bias power, and a test recording signal is recorded by laser light (test recording is performed). The recommended bias power value read from the device memory 14 is a fixed value of 0.7 mW or less, for example.

  The DC erasing unit 5 as a specific configuration of the present embodiment has only the erasing power of the laser beam in the same region with respect to a predetermined OPC address region in which test recording is performed by the recording unit 6 under a certain recording condition. As shown in Fig. 4, recording is performed while changing the power level step by step. In this case, the DC erasing means 5 calculates the optimum recording power value (Pind), the recording power / erasing power ratio ε, and the optimum erasing power read from the optical disk 1 or the device memory 14. A DC erasing power value (= ε · Pind / S) close to the reference is obtained by calculation from a value of a predetermined coefficient (hereinafter referred to as coefficient S) multiplied by, and a DC erasing power value around the reference value Is variable. The value of the recording power and erasing power ratio ε read from the device memory 14, the recommended recording power value (Pind), and the predetermined coefficient S to be multiplied for calculating the optimum erasing power are in accordance with the type of the optical disc. It is a value set corresponding to this optical disk recording / reproducing apparatus. When a more reliable value is stored in the device memory 14 due to the learning function or control program update, the optical disk recording / reproducing device selects the value stored in the device memory 14 with priority. You may do it.

  Then, the area of the same OPC address is reproduced and the change in recording state is recorded by the recording state detecting means 4 on the optical disk for each area recorded by the DC erasing means 6 with the erasing power varied stepwise as shown in FIG. Of the reproduction RF signal from 1 or a parameter obtained by differentiating the modulation degree characteristic (hereinafter referred to as γ value) or an asymmetry value or β value (hereinafter also referred to as β value for asymmetry) of the parameter representing the asymmetry of the RF signal. Detect by measuring.

  Measurement of the modulation degree or γ value of the RF signal or the β value for asymmetry is performed with the configuration of the block diagram shown in FIG. 3 (the configuration and operation of this block diagram will be described in detail later). The measurement result of the recording state detected by the recording state detection means 4 is transferred to the control circuit 11 via the internal bus 10 in the signal processing circuit 3 of FIG. The control circuit 11 includes predetermined values (modulation degree, γ value condition, asymmetry β value) predetermined by the control program stored in the device memory 14 and the detected recording state input from the signal processing circuit 3. The determination unit 13 compares the measurement results of the above and determines the DC erase area of the optical disc 1 that shows the coincidence or the closest value, and obtains the value of the erase power performed in the DC erase area.

  The value of this erasing power is used as a reference value, and the arithmetic means 12 in the control circuit 11 performs a multiplication process using a predetermined coefficient S optimum for this type of optical disk 1 stored in advance in the device memory 14, The optimum erasing power value is obtained. As described above, the optimum erasing power for the optical disc 1 can be obtained by the OPC process of the present invention.

  Next, the block configuration and operation of the recording state detecting means 4 and the control circuit 11 according to the present invention will be described with reference to FIGS. FIG. 3 shows a block diagram of an embodiment of a part of the recording state detection means 4 and the control circuit 11. The recording state detection means 4 or the like can detect and measure the modulation degree or γ value or asymmetry β value of the reproduction RF signal. In FIG. 3, reproduced RF signals from a plurality of DC erasure areas recorded by changing the DC erasure power of the optical disk 1 stepwise by the optical pickup 2 of FIG. 1 are AC-coupled by a high-pass filter (HPF) 100. The amplitude level on the positive side (upper side) with respect to 0V is detected by the peak level detection circuit 101, and the signal fluctuation due to the droop characteristic of the peak level detection circuit 101 is averaged by the low-pass filter (LPF) 104 in the next stage. Is output as signal A1.

  On the other hand, in the reproduction RF signal AC-coupled by the HPF 100, the amplitude level on the negative side (lower side) with respect to 0V is detected by the bottom level detection circuit 102, and the LPF 105 in the next stage depends on the droop characteristic of the bottom level detection circuit 102. Signal fluctuations are averaged and output as signal A2. The asymmetry β value of the parameter representing the asymmetry of the RF signal is calculated from the signal A1 and the signal A2 by the following formula. This calculation is performed by the calculation means 107.

β value = (A1 + A2) / (A1-A2) (1)
The asymmetry β value calculated by the calculation means 107 is compared with a predetermined asymmetry β value by the comparison determination circuit 110. The comparison determination circuit 110 shows the processing contents of the determination means 13.

  The actual RF signal is shown in FIG. 4A, and the levels of the signals A1 and A2 are shown in the figure. FIGS. 4B to 4D show the characteristics of a DVD-RW double-layer optical disc. FIG. 4B is a graph of the asymmetry β value by varying the recording power. As a characteristic, the test recording signal is recorded on the first recording layer once (initial), twice (DOW1), When it is repeatedly performed 11 times (DOW10), although there is a characteristic difference due to the difference in the number of repeated recordings, the peak position is in the vicinity of the same. From this, it can be seen that there is a possibility that it can also be used for β value detection for asymmetry. That is, the maximum amplitude point of each curve in FIG. 4B is regarded as the best point of the reproduction jitter after recording, and this position is almost regarded as the optimum recording power position. It can be used for calculation as the optimum recording power without the influence of the difference.

  FIG. 4C shows a graph of asymmetry β values with the recording power kept constant and the erasing power varied. That is, of the pulses shown in FIG. 16A, the write power (recording power) Pw and the bias power Pb are fixed at fixed values, and only the erase power Pe is varied and recording is performed. A characteristic diagram with the β value for use is shown. This characteristic has a large difference in recording characteristics depending on the number of repeated recordings, and there are many variations in the position of the graph. For example, when the erasing power Pe of β = 0 is obtained, it has an error of about 0.8 mW. As can be seen from the graph of erase power versus jitter in FIG. 18B, the erase power margin is very small and needs to be set with high accuracy within ± 0.4 mW, and this asymmetry is taken into account when detection variations are considered. However, there is a difficulty in practical use in detecting the β value.

  FIG. 4D shows a DC erasing power vs. β value characteristic diagram in which the DC erasing β characteristic is measured using the OPC technique of the present invention. This characteristic diagram shows the recording areas of one-time recording (initial), two-time repeated recording (DOW1), and eleven-time repeated recording (DOW10) in the OPC area of the first recording layer of the two-layer optical disc. As shown in FIG. 4, after recording with only the erasing power whose level is variable (DC erasing), the asymmetry β value is detected from the reproduction RF signal obtained by reproducing the area, but it depends on the number of repeated recordings. It can be seen that there is almost no difference in the recording characteristics and the characteristics are almost the same.

  Using this characteristic, the comparison / determination circuit 110 in FIG. 3 (corresponding to a part of the determination unit 13 in FIG. 1) is used as a predetermined β value to be compared with the β value from the calculation unit 107 in FIG. For example, by using the value “−40”, it is possible to detect the reference value of the erasing power with little error. The optimum erasing power can be obtained by multiplying the reference erasing power by the coefficient Sb for obtaining the optimum erasing power as the coefficient Sb. According to the experiment, the error from the optimum erasing power was within 4%.

  Next, detection of the modulation degree (m) will be described. In FIG. 3, the reproduction RF signal is branched into two, one is input to the HPF 100 and the other is input to the peak level detection circuit 103. The peak level detection circuit 103 measures the amplitude voltage of the reproduction RF signal from the DC level reference voltage, supplies the detected voltage to the LPF 106 at the next stage, and averages the signal fluctuation due to the droop characteristic of the peak level detection circuit 103. The signal A3 is output.

  The value of the degree of modulation m is calculated by the calculation unit 108 from the signals A1 and A2 output from the LPFs 104 and 105 and the signal A3 by the following equation.

Modulation degree m = I14 / I14H
= (A1-A2) / A3 (2)
In the above equation, I14 is the amplitude value of the RF signal (specifically, the 14/16 signal of the 8/16 modulation method), and I14H means the amplitude value from the reference value of the DC level to the upper envelope of the RF signal. ing.

  The modulation factor m calculated by the computing means 108 is supplied to the comparison / determination circuit 111 and compared with a predetermined modulation factor value. Note that the comparison / determination circuit 111 in FIG. 3 shows the processing contents of the determination means 13 in FIG.

  The actual RF signal is shown in FIG. 5A, and each level of the amplitude value I14 of the RF signal and the amplitude value I14H from the reference value of the DC level to the envelope on the upper side of the RF signal is shown in FIG. . FIG. 5B shows a recording power versus modulation degree characteristic in which the recording power is varied and the modulation degree m is graphed. As shown in FIG. 5B, when recording of the test recording signal on the first recording layer is repeated once (initial), twice (DOW1), and 11 times (DOW10), 2 of DVD-RW. Although there is a slight difference in recording power versus modulation characteristics depending on the number of repeated recordings mentioned as a problem of the layered optical disk (difference of about 0.2 mW), the optimum erasing power is within the range of about ± 0.4 mW. Then, it turns out that it is a level that can be used sufficiently.

  FIG. 5C shows erasing power versus modulation degree characteristics in which the recording power is made constant and the erasing power is varied to graph the modulation degree. That is, of the pulses in FIG. 16A, the erasing power and modulation when recording is performed by fixing the writing power (recording power) Pw and the bias power Pb at fixed values and varying only the erasing power Pe. Degree characteristics. As shown in FIG. 5C, when the recording is repeated at the first time (initial), the second time (DOW1), and the eleventh time (DOW10), the modulation degree is almost constant even if the erasing power is varied. It can be seen that this method cannot be used to detect the optimum erasing power.

  FIG. 5D shows the DC erasing power versus modulation degree characteristic performed using the OPC technique of the present invention. That is, the characteristic shown in FIG. 5D is that the areas where the recording is repeated first (initial), second (DOW1), and eleventh (DOW10) are performed only with the erasing power, and the level is as follows. When recording is performed in a variable manner (DC erasure is performed), it can be seen that there is a slight difference in recording characteristics depending on the number of repeated recordings, but the characteristics are almost the same.

  By using, for example, a value of “0.3” in FIG. 5D as a predetermined modulation degree value (m value) to be compared in the comparison determination circuit 111 in FIG. It is possible to detect the reference value of the erasing power with a small error. The optimum erasing power can be obtained by multiplying the reference erasing power by the coefficient Smod for obtaining the optimum erasing power as a coefficient Smod. According to the experiment, the error from the optimum erasing power is within 5%.

  Although the asymmetry value of the parameter representing the asymmetry of the RF signal is omitted in the description of the β value, similar detection and effect can be expected. As the configuration for detecting the asymmetry value, the β value detection configuration and the modulation degree detection configuration can be used. That is, the asymmetry value is calculated by the following equation using the signal A1, the signal A2, and the signal A3. This calculation is performed by the calculation means 12 (not shown in FIG. 3).

Asymmetry = [(I14H + I14L) − (I3H + I3L)] /
2 [(I14H-I14L)] (3)
In the above equation, I14H, I14L, I3H, and I3L are shown in the waveform of the RF signal shown in FIG. 5A, and these are expressed by the following equations using the signals A1, A2, and A3. .

I14H = A3 (4)
I14L = A3- (A1-A2) (5)
I3H = A3 (6)
I3L = A3- (A1-A2) (7)
In this detection, when the recording waveform pattern of the test recording signal is, for example, 8/16 modulation, recording is performed in the PCA area (PCA area 311 in FIG. 15) while alternately outputting a single pattern of 3T and 14T as one set. To the area from a predetermined address. When DC erasing power is applied to the area from the same address, recording is performed while changing the power step by step for each set. The above recording is for the first recording layer for a two-layer optical disc.

  Next, when reproducing the area from the same address and detecting the recording state, the levels of the respective RF signals are reproduced at the timing corresponding to the writing area of 3T and 14T, and the signals A1, A2 and A3 are obtained. By detecting, the above calculation can be realized. Note that the coefficient S to be calculated as the DC erasing power when the coincidence is detected by the determination unit 13 is a coefficient Sa.

  Next, detection of the parameter γ will be described. A PCA area recorded in advance as a test record is recorded while varying the DC erasing power step by step as shown in FIG. 2, and the same area is reproduced to detect the modulation level m obtained from the recording state detection means 4 Is stored in the device memory 14 of FIG. 1 for each step. Then, as shown in FIG. 3, based on the data from the device memory 14, “amount of change (dm) of the modulation degree m from one step ahead” 113 and “amount of change of the erasing power from one step ahead (dPe)”. ) “114”, “value of modulation m at current step (m)” 115, and “value of DC erasing power at current step (Pe)” 116.

  It should be noted that the reference content 113 of the memory for each step is “change amount (dm) after 1 step and 1 step after the modulation degree m”, and the reference content 114 is “1 step ahead and 1 step after the erase power”. The amount of change (dPe) ”may be used.

  From these values, the erasing power parameter γ (Pe) is calculated by the following equation by the calculating means 109 shown in FIG.

γ (Pe) = (dm / dPe) / (m / Pe) (8)
The erasing power parameter γ calculated by the computing means 109 is supplied to the determination circuit 112 to determine the minimum peak point of the γ value.

  Although the recording power parameter γ (Pw) is not shown in FIG. 3, it is calculated in the same manner by replacing the values 113 to 116 as follows.

113: “Amount of change m after one step of modulation degree m (dm)”
114: “Change in recording power one step ahead and one step after (dPw)”
115: “value of modulation m at current step (m)”
116: “Recording power value at the current step (Pw)”
From these values, a recording power parameter γ (Pw) is calculated by the following equation.

γ (Pw) = (dm / dPw) / (m / Pw) (9)
FIG. 6A shows a general characteristic diagram of the degree of modulation with respect to the recording power (writing power) Pw and the parameter γ (Pw). In order to obtain the optimum recording power Po, the γ target (γtarget) in FIG. 6A is determined, the recording power (Ptarget) where the detected γ characteristic coincides with this γ target is obtained, and this value is obtained. Multiply by a coefficient ρ as a reference value to obtain by calculation. Note that the coefficient ρ is adjusted to the recording power and erasing power at which the jitter of DOW1 is minimized in view of the characteristic diagram of FIG. This is because the best recording (minimum reproduction jitter) can be performed under the recording condition (DOW1) which is the most disadvantageous in the design of the recording / reproducing apparatus.

  FIG. 6B shows the result of measuring the recording power and the parameter γ (Pw) of the DVD-RW double-layer optical disk using this method with the ratio ε of the recording power and the erasing power kept constant. As a characteristic, even if recording on the first recording layer of the double-layer optical disk is repeated first (initial), second (DOW1), and eleventh (DOW10), it is a problem of the DVD-RW double-layer optical disk. It can be seen that the change in the recording characteristics due to the number of repeated recordings mentioned is relatively small and can be sufficiently detected by the method described with reference to FIG. 6A (γ method).

  FIG. 6C shows a characteristic diagram in which the parameter γ (Pe) is measured by reproducing an area recorded by changing only the erasing power Pe in the pulse of FIG. As shown in FIG. 6C, this characteristic shows that γ (Pe) changes so much depending on the erasing power even if the recording is repeated first time (initial), second time (DOW1), and 11th time (DOW10). Thus, it can be seen that it cannot be used to detect the optimum erasing power.

  FIG. 6D shows the DC erasing power and parameters measured from the areas recorded at the first (initial), second (DOW1), and eleventh (DOW10) test recording signals using the OPC technique of the present invention. The measurement result with γ (Pe) is shown. This characteristic is a graph (normalized slope characteristic of the modulation degree) obtained by differentiating the characteristic of the modulation degree. It can be seen from FIG. 6 (D) that the portion where the degree of modulation attenuates due to abrupt DC cancellation has a large peak (dip). It can be seen that the position of the peak portion of this peak occurs at almost the same point without being affected by the change in the recording state depending on the number of repeated recordings. The OPC according to the present invention performs detection with the characteristics of a region where the residual amplitude of the test recording signal that has been DC-erased does not completely disappear.

  From such characteristics, the optimum erasing power can be obtained by using the DC erasing power corresponding to the peak of this peak as a reference value and multiplying by a predetermined coefficient Sg for obtaining the optimum erasing power. According to the experiment, the error from the optimum erasing power was within 3%.

  The coefficient Sb, the coefficient Smod, the coefficient Sg, and the coefficient Sa used in the present embodiment are determined in advance as values for obtaining the erasing power that provides the best jitter at the second rewrite count. As shown in FIG. 17, this is determined in view of the relatively poor reproduction jitter at the time of the second recording, whereby the optimum erasing power can be set in a short time. Note that the value of each coefficient described above varies depending on the characteristics of the recording layer of the optical disc.

  FIG. 20 shows the measurement result of the variation of the coefficient Sg. It has been found that the optimum erasing power can be obtained by setting the range of the set value of the coefficient Sg to 1.0 or more and near 1.6 (in the case of more margin, it is set to near 1.7). The measurement is performed by recording three types of sample discs as RW2 layer A, RW2 layer B, and RW2 layer C, and recording each optical disc with four different recording devices (device A, device B, device C, device D). After test recording is repeated 11 times, DC erasure is performed (DOW10), a γ value is obtained from the residual amplitude of the recording signal, and a reference value of DC erasing power is obtained from the peak point. Then, the coefficient Sg is obtained by the following calculation formula from the reference value of the DC erasing power and the erasing power value under the condition that the optimum recording can actually be performed.

Sg = (Erase power value in optimum recording state) / (Reference value of DC erase power)
The actually measured value of the coefficient Sg was 1.0 to 1.22 at the minimum from the graph of FIG. The variation of the coefficient Sg of each disk of the RW2 layer is within ± 10%. Considering disc manufacturing variations and disc characteristics of RW2 layers to be released in the future, if a margin of 20% to 30% is expected for the maximum coefficient Sg of 1.22, the coefficient Sg is around 1.5 to 1.6. I understand that it is enough. Further, if the margin is estimated to 40% with a margin, it can be seen that the coefficient Sg is sufficient to be close to 1.7. As for the minimum value of the coefficient Sg, a value smaller than 1.0 is realistic because there is a problem that, if the erasing power under the actual optimum recording condition is lower than the detected DC erasing power, an erasing residue occurs. is not. Therefore, the minimum value of the setting range of the coefficient Sg is set to 1.0.

  Next, an actual setting example of the optimum write power according to the present embodiment will be described with reference to the flowchart of FIG. When the test recording mode of the OPC process is instructed, the control circuit 11 shown in FIG. 1 enters a test recording process for obtaining an optimum recording power. Before that, a process (subroutine A) for initializing the PCA area is performed. May be executed. Thereafter, the recommended recording power value is read from the optical disc 1 or the device memory 14 as a fixed value, and the erasing power is also based on the value of ε (ratio of the erasing power to the recording power) read from the optical disc 1 or the device memory 14. The bias power is obtained by multiplying by the recording power, and the bias power is set in the recording means 6 of FIG. 1 with the value read from the device memory 14 as a fixed value (step 201).

  Subsequently, the test recording signal to be recorded is set to a random pattern signal (EFM signal) of a recording waveform pattern, and the recording strategy and the writing power (recording power Pw, erasing power Pe, bias power Pb) are set as constant conditions. Test recording is performed in the OPC area (corresponding to 311 in FIG. 15) of the first recording layer of the optical disc 1 (step 202). Subsequently, the same area as the test-recorded OPC area is recorded (DC erased) while being varied stepwise (for example, 10 steps) with the DC erase power. The value of the DC erasing power at this time is recorded in the device memory 14 for each step (step 203).

  Then, in order to detect a change in the recording state due to DC erasure, the OPC area after DC erasure is reproduced (step 204). Of the RF signal obtained by reproduction, the degree of modulation m is calculated from the RF signal for each area recorded in the OPC area by changing the level for each step of the DC erasing power, and the γ value is further calculated. Alternatively, the asymmetry β value is calculated. The obtained value is stored in the device memory 14 (step 205).

  Subsequently, it is determined from the outputs of the comparison determination circuits 110, 111, and 112 shown in FIG. 3 whether the calculated asymmetry β value, modulation degree m, and γ value coincide with predetermined values (step 206). As a result of the determination, the DC erasing power value at the matched step is obtained, and the optimum erasing power is calculated by multiplying the DC erasing power value as a reference value by the coefficient Sb, the coefficient Smod or the coefficient Sg (step 207).

  Subsequently, the calculated erasing power is set as a fixed value, the recording power is calculated based on the value of ε read from the optical disk 1 or the device memory 14 and set as a fixed value, and the bias power is a value read from the device memory 14 as a fixed value. Is set in the recording means 6 (step 208). Finally, all of the optimum writing power (recording power Pw, erasing power Pe, bias power Pb) is determined, and the OPC operation is terminated (step 209).

  Thus, according to the present embodiment, the setting tolerance of the recording power is relatively wide from FIG. 18A, and the setting tolerance of the erasing power of the first recording layer of the double-layer optical disc is FIG. Since (B) and FIG. 19 are extremely narrow, first, the optimum erasing power is detected accurately, and the recording power is obtained using ε from the obtained erasing power, so that the optical disc is tested for OPC processing. There is a feature that the number of times of recording can be reduced and the starting time of the drive device can be substantially reduced.

(Second Embodiment)
In the first embodiment described above, test recording is performed on an optical disc using a test recording signal in which a short mark and a long mark of a recording waveform pattern are mixed or a random pattern signal of a recording waveform pattern as a test recording signal. Although the test recording area was erased by gradually increasing the DC erasing power, the short mark was erased first, and the amplitude of the RF signal was attenuated. Is high.
This seems to be because the amplitude of the recording mark detected by the peak level detection and the bottom level detection mainly detects the remaining unerased degree.

  Therefore, in the second embodiment, in order to improve detection accuracy, test recording is performed using only the longest long mark (14T signal in the case of 8/16 modulation signal) as the test recording signal. The basic configuration of the optical disc recording / reproducing apparatus and the procedure of the recording process are the same as those shown in FIGS. 1 to 3 and FIG. explain.

  FIG. 8 is obtained by performing test recording using a 14T signal as a test recording signal, recording (erasing) the recording area by changing the DC erasing power stepwise, and then reproducing the DC erasing portion. FIG. 6 is a characteristic diagram of the present embodiment showing a relationship with an erasing power parameter γ (Pe) value. In FIG. 8, when DC erasing is performed while the portion where the 14T signal is recorded once is varied stepwise with the DC erasing power (initial), the portion where the 14T signal is recorded twice in total is recorded stepwise with the DC erasing power. When DC erasure is performed while changing (DOW1), the parameter γ (Pe) is changed with respect to each of cases where DC erasure is performed while changing the portion where the 14T signal is recorded a total of 11 times stepwise with the DC erasing power (DOW10). The experimental result which measured (gamma) value which is a parameter which shows the normalized inclination characteristic of a modulation degree is shown.

  As can be seen from FIG. 8, there is a point where this detection characteristic changes sharply and erasure is abruptly performed slightly before complete erasure. The present embodiment utilizes the fact that this point can be detected with little influence on the repetitive recording characteristics, and an optimum erasing power is derived by multiplying a predetermined coefficient on the basis of the erasing power at this point. The error from the optimum erasing power in this case was within 2%.

  Therefore, the test recording signal may be the longest mark signal of the recording mark of the recording waveform pattern or a long mark including the longest mark signal (for example, any mark signal of 8T to 14T in the case of 8/16 modulation signal) or a single mark. It can be seen that good results can be obtained by performing test recording on an optical disk using a long mark (for example, in the case of an 8/16 modulation signal, an arbitrary mark signal from 8T to 14T).

(Third embodiment)
In the first embodiment and the second embodiment described above, the DC erase power at the determination means 13 that matches the predetermined value is used as a reference value in order to obtain the optimum write power. An optimum erasing power is obtained by multiplying a predetermined coefficient Sb or coefficient Smod or coefficient Sg. However, in this case, when it becomes necessary to perform an OPC process on an optical disk of a newly entered optical disk manufacturer or an optical disk having no data in the device memory 14, a problem that the OPC process cannot be performed occurs.

  Therefore, in the third embodiment, in order to solve this problem, the values of the predetermined coefficient Sb, coefficient Smod, and coefficient Sg are recorded in advance in the prepit area or track groove information in the optical disk. Therefore, the structure of the optical disc is characteristic. In this case, it is necessary to perform management that can be distinguished so as to correspond to the type of detection means of the modulation degree method or the asymmetry β method or γ method used in the recording state detection means 4, and is defined in advance when referring to the optical disc information. There is a need.

  Specifically, the values of the respective coefficients are encoded and recorded in a form that is not erased in advance at a predetermined address in the LPP or control data zone when the disc is manufactured. The recording position as the LPP may be a PCA area or an RMA area, but is not limited to this and may be anywhere on the optical disk. As shown in the DC erasing power coefficient table of FIG. 9B, this code defines a DC erasing power coefficient S (a value corresponding to the coefficient Sb and the coefficient Smod and the coefficients Sg and Sa). The DC erasing power coefficient table is stored in the device memory 14 as a program.

  Further, the address table of FIG. 9A corresponds to the address on the LPP or the control data zone, and shows an address portion where the DC erasing power coefficient is stored. The byte position of the address is represented by N to N + 3, the content of the address N is the code of the coefficient Smod for the modulation factor method, the content of the address N + 1 is the code of the coefficient Sb for the β method, and the address N + 2 is the coefficient Sg for the γ method The address N + 3 means the code of the coefficient Sa of the asymmetry method. For example, 06h is stored in the byte position N, which is a coefficient Smod for the modulation factor method, and the value is “1.30” from FIG. 9B.

  As another example, without using the DC erasing power coefficient table of FIG. 9B, an arithmetic expression as shown below is determined in advance, and the code in the coefficient address is substituted into the arithmetic expression. Thus, the coefficient Sg may be calculated.

Sg = 0.99 + (coefficient Sg code × 0.01)
(However, the code of the coefficient Sg is a hexadecimal number from 01h to 3Fh.)
Specifically, the coefficient Sg can be obtained as a value of 1.0 to 1.62 by substituting the code setting range of the coefficient Sg into the above arithmetic expression.

  By adopting a structure in which the optical disk 1 has this DC erasing power coefficient in advance, the OPC process of the present invention can be executed with information from the optical disk, and an optimum write power can be set even for an unknown optical disk or the like. You can do it. In this embodiment, the basic configuration of the optical disc recording / reproducing apparatus and the recording processing procedure are the same as those in the first embodiment shown in FIGS.

(Fourth embodiment)
The present embodiment is an example provided with means for performing detection with higher accuracy in order to detect optimum erasing power. This means performs processing for detecting an optimum erasing power after the PCA area is initialized with the DC erasing power in advance. Although it has been described in the above embodiment that optimum recording can already be performed based on the γ value, detection performance can be improved particularly with other parameters of modulation degree and β value. The basic configuration of the optical disc recording / reproducing apparatus and the procedure of the recording process are the same as those shown in FIGS. 1 to 3 and FIG. explain.

  FIG. 10 is a characteristic diagram of an example of the asymmetry β value and the initialization power. FIG. 10 shows a case where the PCA area of the first recording layer to be test-recorded is initialized by previously varying the DC erasing power, and then the repetitive recording characteristics of the asymmetry β value are measured. In FIG. 10, when the DC erasing power (initialization power) at the time of initialization processing is 0 mW, this corresponds to the case where the asymmetry β value is measured without performing initialization. In such a case, it can be seen that the characteristics of repetitive recording (initial recording, repetitive recording first time, repetitive recording 10th time) do not match and are greatly deviated. Thus, if the change is large in repeated recording, it becomes difficult to detect the optimum recording power using the asymmetry β value as an index.

  As shown in FIG. 10, it can be seen that the repetitive recording characteristics gradually match when the initialization power exceeds 8 mW. Therefore, in the case of this optical disc, since the optimum erasing power (Pe) was 5.85 mW, the DC erasing power for the initialization process is 9 mW to 14.5 mW, which is slightly higher than the optimum erasing power (Pe). It can be seen that if the degree (W in FIG. 10) is satisfied, it is possible to obtain a state in which the dependency of repeated recording is small. As a guideline, it is sufficient that the power is 1.5 to 2.5 times the optimum erasing power (this processing is hereinafter referred to as high power initialization processing). The PCA area of the first recording layer for OPC is subjected to high power initialization processing only once at 13 mW, which is about twice the optimum erasing power, and then the characteristics are confirmed for the modulation factor, γ value, and asymmetry β value. The result of having performed is shown.

  FIGS. 11A and 11B show characteristic diagrams of DC erasing power and β value, FIG. 11A shows the characteristics without initialization, and FIG. 11B shows the characteristics with initialization. FIGS. 12A and 12B show characteristics of the DC erasing power and the modulation degree, FIG. 12A shows the characteristics without initialization, and FIG. 12B shows the characteristics with initialization. 13A and 13B show characteristic diagrams of DC erasing power and γ value, FIG. 13A shows a characteristic without initialization, and FIG. 13B shows a characteristic with initialization, respectively. .

  In FIGS. 11 to 13, when the DC erasing power is varied and the DC erasing power is changed (initial) at a portion where the test recording signal is recorded once in the PCA area of the first recording layer, the test recording signal is In the case where the DC erase power is changed and the DC erase power is varied at a place recorded twice (DOW1), and the test record signal is recorded 11 times in the DC erase power and the DC erase power is varied (DOW10). ) Shows the experimental results of measuring the β value, the degree of modulation, or the γ value.

  The characteristics shown in FIG. 11B and FIG. 12B of the initialized one have less variation due to repetitive recording around the reference value, and it can be seen that the detection performance is improved as compared with the case where the initialization is not performed. . In FIG. 13B, which has been initialized, the detection performance is good and there is little variation, so no significant performance improvement is seen. However, since the peak amplitudes match, the detection characteristics are stable. It seems that there is. Thus, if the high power initialization process is performed once before the OPC, the characteristics of the recording layer of the optical disc are made uniform. The characteristics shown in FIGS. 11B, 12B, and 13B show a case where a dual-layer DVD-RW disc is used and a high power initialization process is performed at a double rotational speed.

  FIG. 14 shows a flowchart of the fourth embodiment of the optical disc recording / reproducing method of the present invention. FIG. 14 corresponds to a subroutine that can be appropriately subjected to additional processing immediately before step 201 in FIG. 7 if necessary, and whether or not to perform the above high power initialization processing is determined by a record management area determination flag. An example of the operation managed is shown.

  In FIG. 14, when the processing of subroutine A is started at step 500, first, the PCA area (FIG. 15) of the optical disk is read from the flag information read from the recording management area (for example, corresponding to the RMA area 312 of FIG. 15). It is confirmed whether or not the high power initialization process is performed in the PCA area 311 (step 501). If the PCA area has been subjected to high power initialization processing (Y), it is determined whether or not the PCA area has been exhausted (step 506). If the PCA area has been exhausted (Y), all PCA areas are recommended. Initialization is performed with the DC erase power of the erase power value (= ε · Pind) or the optimum erase power (Pe) (step 507), and the subroutine A is terminated (step 508).

  On the other hand, when the high power initialization process of the PCA area is not performed (N in Step 501), it is determined whether the PCA area is used from the beginning or whether the PCA area is used up (Step 502). If the PCA area is in a state of being used from the beginning (Y), the PCA area has a DC erasing power about twice the calculated recommended erasing power value (= ε · Pind) or the optimum erasing power (Pe). Is initialized (step 503). Then, a flag is recorded in the recording management area (RMA area) as the high power initialization process is completed (step 505), and the subroutine A is terminated (step 508). In this case, the entire PCA area is subjected to the high power initialization process.

On the other hand, if it is determined in step 502 that the PCA area is not used from the beginning and it is determined that the PCA area is not used up (N), that is, the PCA area is used without performing high power initialization processing. In the case where the PCA area is used, only the OPC area to be used is subjected to a high power initialization process in the PCA area with a DC erasing power approximately twice the recommended erasing power value (= ε · Pind) or the optimum erasing power (Pe) (step 504), the subroutine A is terminated (step 508).
Also in this case, when all the PCA areas are used up, the entire PCA area can be set to the high power initialization process in step 503 via step 502.

  The present invention is not limited to the above embodiment. For example, the optical disc 1 is not limited to a single-sided dual-layer optical disc having the cross-sectional structure shown in FIG. The present invention can be applied to recording / reproduction of the first recording layer of a multilayer optical disc laminated in the beam optical axis direction. The present invention also includes a computer program that causes a computer to execute the configuration of FIG. 1, the flowchart of FIG. 7, or the flowchart of FIG. In this case, the computer program may be taken into the computer from a recorded recording medium, or may be delivered via a network and taken into the computer. Furthermore, it may be originally incorporated as firmware in the apparatus.

1 is a block diagram of an embodiment of an optical disc recording / reproducing apparatus of the present invention. FIG. It is a wave form diagram which shows the stepwise power change of the laser beam power for DC erasing of a phase change type optical disk. FIG. 2 is a block diagram of an embodiment of a part of a recording state detection unit and a control circuit in FIG. 1. FIG. 2 is an explanatory diagram for detecting an asymmetry β value of the recording state detection means in FIG. 1, a recording power versus β value characteristic, an erasing power versus β value characteristic, and a DC erasing power versus β value characteristic. FIG. 2 is an explanatory diagram for detecting a modulation degree m of the recording state detection means in FIG. 1, showing recording power versus modulation characteristic, erasing power versus modulation characteristic, and DC erasing power versus modulation characteristic. FIG. 2 is an explanatory diagram for detecting the γ value of the recording state detecting means in FIG. 1, showing recording power vs. γ value characteristics, erasing power vs. γ value characteristics, and DC erasing power vs. γ value characteristics. 4 is a flowchart for explaining a control operation in a test recording mode according to the present invention. FIG. 6 is a characteristic diagram showing characteristics of DC erasing power and γ value when a longest mark is used for a test recording signal. It is a figure which shows an example of the address table | surface of various coefficient information of DC erasing power stored in the optical disk of this invention, and a DC erasing power coefficient table | surface. It is a characteristic figure of an example of beta value for asymmetry, and initialization power. FIG. 5 is a DC erasing power vs. β value characteristic diagram without initialization and a DC erasing power vs. β value characteristic diagram with initialization. FIG. 6 is a DC erasing power vs. modulation factor characteristic diagram without initialization and a DC erasing power vs. modulation factor characteristic diagram with initialization. FIG. 6 is a DC erasing power vs. γ value characteristic diagram without initialization and a DC erasing power vs. γ value characteristic diagram with initialization. It is a flowchart of 4th Embodiment of the optical disk recording / reproducing method of this invention. It is a figure which shows the schematic structure cross section of an example of a 2 layer DVD-R disc and a 2 layer DVD-RW disc. It is a figure which shows the waveform diagram which shows the change of the laser beam power for recording of a phase change type optical disk, and the pit formed. It is a figure which shows the change of the reproduction jitter with respect to the number of times of repeated recording. It is a figure which shows the characteristic of recording power, erasing power, and reproduction | regeneration jitter. It is a figure which shows the characteristic of ratio (epsilon) of erasing power with respect to recording power when a recording power is made constant, and a jitter. It is a figure which shows the measurement result of the variation of coefficient Sg.

Explanation of symbols

1 rewritable optical disc having a plurality of recording layers 2 optical pickup 3 signal processing circuit 4 recording state detecting means 5 DC erasing means 6 recording means 10 internal bus 11 control circuit 12 calculating means 13 judging means 14 device memory 100 high-pass filter ( HPF)
101, 103 Peak level detection circuit 102 Bottom level detection circuit 104, 105, 106 Low-pass filter (LPF)
107, 108, 109 arithmetic means 110, 111 comparison judgment circuit 112 minimum peak point judgment circuit of γ value

Claims (3)

In an optical disc recording / reproducing apparatus for performing recording / reproduction using a laser beam having a set power for a rewritable optical disc having a multilayer recording layer,
Recording power for changing the recording layer from the crystalline state to the amorphous state under predetermined recording conditions, erasing power for changing the recording layer from the amorphous state to the crystalline state, and preventing thermal diffusion during recording to the recording layer Recording means for recording a test recording signal in a predetermined area of the optical disc with the laser light in which the set recording power, the erasing power and the bias power are changed in a predetermined order.
The laser having only the DC erasing power which is an erasing power whose level changes stepwise with respect to the power related to the set erasing power for the area of the optical disc in which the test recording signal is recorded by the recording means DC erasing means for recording by light;
The area recorded with the DC erasing power is reproduced by the DC erasing means, the modulation degree of the reproduction signal, the γ value that is a parameter indicating the normalized slope characteristic of the modulation degree, and the reproduction signal Recording state detection means for detecting at least one of parameters (β value or asymmetry value) representing asymmetry;
Among the recording was carried out by the DC erase power by DC erasing means, the recording state detecting means from different regions erasing power each other are respectively detected value, predetermined detection value or detection condition for DC erasing power Determining means for determining a detection value that matches
An arithmetic means for multiplying the erasing power value recorded for the area where the detection values coincide with each other by the determination means by a predetermined coefficient to obtain an optimum erasing power level at the time of optical disc recording ;
Before recording the test recording signal, an initialization means for DC erasing the optical disk with an initialization power set to a value 1.5 to 2.5 times the recommended erasing power is provided. An optical disc recording / reproducing apparatus characterized in that an optimum erasing power value is derived. In an optical disc recording / reproducing method for performing recording / reproduction using a laser beam having a set power for a rewritable optical disc having a multi-layer recording layer,
Recording power for changing the recording layer from the crystalline state to the amorphous state under predetermined recording conditions, erasing power for changing the recording layer from the amorphous state to the crystalline state, and preventing thermal diffusion during recording to the recording layer And a first step of recording a test recording signal in a predetermined area of the optical disc with the laser beam in which the set recording power, erasing power and bias power are changed in a predetermined order. ,
The area of the optical disc in which the test recording signal is recorded in the first step is determined based on the power related to the set erasing power, and only the DC erasing power which is an erasing power whose level changes stepwise. a second step of performing recording by said laser beam, by reproducing the region subjected to record in the DC erase power by the second step, the modulation degree of the reproduction signal, the normalized of the mutant Furnishing A third step of detecting at least one of a γ value that is a parameter indicating an inclination characteristic and a parameter (β value or asymmetry value) that represents asymmetry of the reproduction signal;
The second was carried out record in the DC erase power by step, in a plurality of erase power is different regions of the values respectively detected by the third step, the predetermined detected value for DC erasing power Or a fourth step of determining a detection value that matches the detection condition;
The erase power value recorded for the said detection value in the fourth step match the region, and the fifth step of obtaining a level of optimum erase power for the optical disk recording by multiplying a predetermined coefficient ,
Before performing the recording of the test recording signal in the first step, the sixth optical disk is erased by DC with the initialization power set to a value 1.5 to 2.5 times the recommended erasing power. and a step, an optical disc recording and reproducing method is characterized in that so as to derive the value of the optimal erase power for the optical disk recording. An optical disc recording / reproducing program for recording / reproducing a rewritable optical disc having a multi-layer recording layer with a laser beam using a computer,
In the computer,
Recording power for changing the recording layer from the crystalline state to the amorphous state under predetermined recording conditions, erasing power for changing the recording layer from the amorphous state to the crystalline state, and preventing thermal diffusion during recording to the recording layer set a bias power to the recording power setting, the first step records make a test recording signal in a predetermined area of the optical disc by the laser beam by changing the erase power and bias power in a predetermined order ,
The area of the optical disc in which the test recording signal is recorded in the first step is determined based on the power related to the set erasing power, and only the DC erasing power which is an erasing power whose level changes stepwise. a second step to I line recording by said laser beam,
Reproducing the area recorded with the DC erasing power in the second step, the modulation degree of the reproduction signal, the γ value which is a parameter indicating the normalized slope characteristic of the modulation degree, and the reproduction signal a third step of causing detecting at least one of the parameters (beta value or asymmetry value) representing the asymmetry,
Wherein the second step was carried out record in DC erase power, among a plurality of different regions erase power each other of the values detected respectively by the third step, the predetermined detected value or an for DC erasing power A fourth step of determining a detection value that matches the detection condition;
The erase power value recorded for the said detection value in the fourth step match the region, and the fifth step of obtaining a level of optimum erase power for the optical disk recording by multiplying a predetermined coefficient ,
Before performing the recording of the test recording signal in the first step, the sixth optical disk is erased by DC with the initialization power set to a value 1.5 to 2.5 times the recommended erasing power. optical disc recording and reproducing program for causing and a step.

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